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BACKGROUND: In the co-culture environment of mesenchymal stem cells and macrophages, mesenchymal stem cells can promote the polarization of macrophages into anti-inflammatory macrophages to reduce inflammation, and macrophages can promote the osteogenic differentiation of mesenchymal stem cells. The co-culture of both plays an important role in regulating the immune system and promoting tissue regeneration. OBJECTIVE: To summarize the methods, influencing factors and possible mechanisms of co-culture between mesenchymal stem cells and macrophages, and to provide theoretical basis and experimental methods for the application of co-culture of mesenchymal stem cells and macrophages in tissue engineering. METHODS: The first author searched the relevant articles published from January 1970 to September 2023 in PubMed and CNK by computer from January to September 2023. The Chinese and English key words were “mesenchymal stem cells, macrophages, co-culture”. Finally, 63 articles were included and analyzed. RESULTS AND CONCLUSION: (1) In vitro co-culture of mesenchymal stem cells and macrophages can be divided into direct contact co-culture and indirect contact co-culture according to the model, and two-dimensional cell co-culture and three-dimensional cell co-culture according to the dimension. (2) The coculture of mesenchymal stem cells and macrophages can promote the polarization of macrophages towards M2 type and enhance the osteogenic effect of mesenchymal stem cells. (3) In the co-culture model, the methods of co-culture, the proportion and time of co-culture, the phenotype of macrophages, and the cell source and conditions all affected the immune regulation of macrophages and the osteogenesis of mesenchymal stem cells. (4) Cell interaction in coculture may regulate the immune function of macrophages, proliferation, migration and osteogenesis of mesenchymal stem cells through cell-secreted soluble factors, extracellular vesicles, cell-cell contact, and metabolic pathways. (5) Mesenchymal stem cells and macrophages can enhance cardiac function after acute myocardial infarction, promote epithelial wound healing, reduce lung inflammation, improve renal function, and accelerate bone repair. (6) There are still some problems in co-culture of mesenchymal stem cells and macrophages, such as the selection of co-culture conditions, the maintenance of good cell state and interaction of co-cultured cells. (7) The co-culture of mesenchymal stem cells and macrophages can improve the local inflammatory microenvironment and promote tissue regeneration and repair, so it will have a broad application prospect in tissue engineering. [ABSTRACT FROM AUTHOR]

BACKGROUND: Due to the small number of autologous bone sources and the risk of immune rejection and disease spread caused by the use of allogeneic bone, artificial bone materials have played an irreplaceable role in bone transplantation today. Along with functional customization, biocompatibility requirements, and the emergence of biodegradable materials, a variety of biomaterials and a variety of preparation methods have emerged. OBJECTIVE: To summarize the preparation methods of scaffolds used in bone tissue engineering, and the advantages and disadvantages, research status and progress of various preparation methods. METHODS: A computer search was conducted on CNKI, WanFang Data, PubMed, and ScienceDirect databases for literature related to bone tissue engineering scaffold from January 2008 to August 2023. Chinese and English search terms were “tissue engineering, bone scaffold, gas foaming, cryotropic gelation, additive manufacturing”. After excluding irrelevant and repetitive studies, a total of 80 articles were retained for summary. RESULTS AND CONCLUSION: (1) Compared with the traditional preparation process of scaffolds, the emerging additive manufacturing and electrospinning technologies have shown great potential in the production of complex structures such as bone and cartilage for tissue engineering in recent years, demonstrating enormous potential. (2) In addition to the advantages of speed, precision and the range of materials used, additive manufacturing methods also provide the feasibility of manufacturing highly complex geometry and topologically optimized structures, achieving precise adjustment and high repeatability of the structure. (3) Electrospinning is one of the most adaptable and promising technologies for the production of a series of fiber mats. The nanofiber scaffolds produced by electrospinning are biomaterials with surprisingly similar microstructures to the cytoplasmic matrix. (4) At present, hydroxyapatite and tricalcium phosphate are the best in ceramic materials, and there are a variety of materials in polymer materials, with excellent biocompatibility. (5) Therefore, the selection of materials should be based on a better understanding of their properties, avoiding complexity, and producing more enhanced scaffolds. However, most of the literature reports so far are exploratory in terms of clinical applicability, and the specific diseases for which they are suitable for treatment remain to be tested. The future development of bone scaffolds is reflected in the following aspects: mechanical properties matching the missing bone, controllable degradation rate, strong ability to promote bone regeneration, and specific functions. [ABSTRACT FROM AUTHOR]

BACKGROUND: Trauma, inflammation, tumors, and other factors commonly result in tissue defects, including damage to bones, joints, skeletal muscles, and associated blood vessels and nerves. Clinically, it is often challenging to repair all the functional injuries involving these tissues, posing great challenges for OBJECTIVE: To elucidate the application of 3D-printed hydrogel biomimetic structures in motor system tissue injuries. METHODS: Relevant literature published from 2003 to 2023 was retrieved from the CNKI, Wanfang Data, and PubMed databases. The Chinese and English search terms were “3D printing, hydrogel, bone, cartilage, muscle, nerve, vasculature, tissue engineering, biomimetics”. After screening, induction and summary, 63 relevant articles were finally included for review. RESULTS AND CONCLUSION: (1) 3D-printed hydrogels can be achieved in several different ways, such as direct 3D printing, hybrid mode 3D printing, or manufacturing 3D bio-inspired structures in hydrogels by printing intermediate molds. Among these manufacturing processes, extrusion-based printing is currently the most widely used for 3D printing hydrogels with bio-inspired structures. (2) Bioprinting hydrogels enables the production of biovascular structures with complex perfusion patterns, and it can induce the formation of biologically relevant, highly organized, and intact blood vessels. (3) By utilizing bioprinting technology, it is possible to mimic the hierarchical structure and function of natural bone, combining hydrogels with different types of cells and growth factors to create tissue engineering scaffolds that closely resemble the composition and structure of natural bone, thereby facilitating better bone regeneration. (4) Neural fiber structure can be bio-inspired by incorporating different fiber materials into the 3D-printed hydrogel conduit structure. (5) Utilizing specific hydrogel formulations, it is possible to simulate muscle bundle structures or engineer muscle tissues integrating blood vessels and nerves, which can enhance the repair of volumetric muscle injuries in vivo. (6) Based on current related research, methacrylated gelatin, which closely resembles the characteristics of the extracellular matrix, is often considered as a raw material for 3D printing various tissue bio-inspired structures. Researchers also incorporate different growth factors or cells into the hydrogels for bioprinting to achieve the desired tissue repair outcomes. (7) Although there is a lack of clinical trial reports on 3D-printed hydrogel bio-inspired structures, this indicates that the clinical translation of such materials still requires a long-term process. Further improvements are needed in terms of clinical applications, as well as comprehensive in vivo safety assessments. [ABSTRACT FROM AUTHOR]

BACKGROUND: Tissue engineering has brought new hope to the clinical challenge of liver failure, and the preparation of plant-derived decellularized fiber scaffolds holds significant importance in liver tissue engineering. OBJECTIVE: To prepare apple tissue decellularized scaffold material by using fresh apple slices and a solution of sodium dodecyl sulfate, and assess its biocompatibility. METHODS: Fresh apples were subjected to decellularization using phosphate buffer saline and sodium dodecyl sulfate solution, separately. Afterwards, the decellularized apple tissues and apple decellularized scaffold materials were decontaminated with phosphate buffer saline. Subsequently, scanning electron microscopy was used to assess the effectiveness of decellularization of the apple materials. Adipose-derived mesenchymal stem cells were extracted from the inguinal fat BALB/C of mice, and their expression of stem cell-related markers (CD45, CD34, CD73, CD90, and CD105) was identified through flow cytometry. The cells were then divided into a scaffold-free control group and a scaffold group. Equal amounts of adipose-derived mesenchymal stem cells were seeded onto both groups. The biocompatibility of the decellularized scaffold with adipose-derived mesenchymal stem cells was evaluated using CCK-8 assay, hematoxylineosin staining, and phalloidine staining. Cell adhesion and growth on the scaffold were observed under light microscopy and scanning electron microscopy. Furthermore, the scaffold was subdivided into the non-induced group and the hepatogenic-induced group. Adipose-derived mesenchymal stem cells were cultured on the decellularized apple scaffold, and they were cultured for 14 days in regular culture medium or hepatogenic induction medium for comparison. Immunofluorescent staining using liver cell markers, including albumin, cytokeratin 18, and CYP1A1, was performed. Enzyme-linked immunosorbent assay was used to detect the secretion of alpha fetoprotein and albumin. Additionally, scanning electron microscopy was employed to observe the morphology of the induced cells on the scaffold, verifying the expression of liver cell-related genes on the decellularized scaffold material. Finally, the cobalt-60 irradiated and sterilized decellularized apple scaffolds were transplanted onto the surface of mouse liver and the degradation of the scaffold was observed by gross observation and hematoxylin-eosin staining after 28 days. RESULTS AND CONCLUSION: (1) The scanning electron microscopy results revealed that the decellularized apple scaffold material retained a porous structure of approximately 100 μm in size, with no residual cells observed. (2) Through flow cytometry analysis, the cultured cells were identified as adipose-derived mesenchymal stem cells. (3) CCK-8 assay results demonstrated that the prepared decellularized apple tissue scaffold material exhibited no cytotoxicity. Hematoxylin-eosin staining and phalloidine staining showed that adipose-derived mesenchymal stem cells were capable of adhering and proliferating on the decellularized apple tissue scaffold. (4) The results obtained from immunofluorescence staining and enzyme-linked immunosorbent assay revealed that adipose-derived mesenchymal stem cells cultured on the decellularized apple scaffolds exhibited elevated expression of liver-specific proteins, including albumin, alpha-fetoprotein, cytokeratin 18, and CYP1A1. These results suggested that they were induced differentiation into hepatocyte-like cells possessing functional characteristics of liver cells. (5) The decellularized apple scaffold implanted at 7 days has integrated with the liver, with partial degradation of the scaffold observed. By 28 days, the decellularized apple scaffold has completely degraded and has been replaced by newly-formed tissue. (6) The results indicate that the decellularized scaffold material derived from apple tissue demonstrates favorable biocompatibility, promoting the proliferation, adhesion, and hepatic differentiation of adipose-derived mesenchymal stem cells. [ABSTRACT FROM AUTHOR]

BACKGROUND: Due to the very limited ability of articular cartilage to repair itself, articular cartilage defects caused by natural degeneration or trauma often cannot be repaired on their own, which triggers or aggravates osteoarthritis and even leads to severe disability. Therefore, the repair treatment after articular cartilage injury has become an urgent clinical problem. OBJECTIVE: To summarize the hot research topics and development trends in the field of articular cartilage repair using bibliometric analysis. METHODS: Literature related to articular cartilage repair was searched from the Web of Science Core Collection from 2000 to 2023, and bibliometric and visualization analyses were carried out using VOSviewer, Citespeace and Bibliometrix R-package. RESULTS AND CONCLUSION: The annual publication volume in the field of articular cartilage repair shows an overall increasing trend, with the United States, China, and Germany being the top three countries in terms of publication volume, and the research institutions focus on universities and hospitals, with Harvard University, New York Hospital for Special Surgery, and Shanghai Jiao Tong University being the top three institutions in terms of publication volume. AMERICAN JOURNAL OF SPORTS MEDICINE is the journal that publishes the most research literature in the field, and BIOMATERIALS is the journal with the highest number of citations in the field. “Injectable hydrogels for cartilage and bone tissue engineering” is the most cited document published in the last decade, and the author with the most publications is Madry Henning, an active author in the field. The active authors in this field have formed a number of stable research teams with each other, and the cooperation between different teams needs to be further strengthened. Intra-articular injections, high tibial osteotomies, hydrogels, drug delivery, inflammation, cartilage regeneration, and scaffolds are the current hot topics of research in this field, and the application of 3D printing technology, bio-inks, silk proteins, injectable hydrogels, and exosomes in articular cartilage repair may be the frontier of research in this field. Integrating various innovative technologies and methods for more effective, durable and functional cartilage tissue regeneration and repair, and facilitating the clinical translation of the relevant technologies and methods by conducting more high-quality clinical studies may be the future research trend in this field. [ABSTRACT FROM AUTHOR]

BACKGROUND: Compared with traditional two-dimensional culture, three-dimensional microtissue culture can show greater advantages. However, more favorable cultivation methods in three-dimensional culture still need to be further explored. OBJECTIVE: To evaluate the cell behavior of microtissue and its ability to promote cartilage formation under two three-dimensional culture methods. METHODS: Cartilage-derived microcarriers were prepared by chemical decellularization and tissue crushing. DNA quantification and nuclear staining were used to verify the success of decellularization, and histological staining was used to observe the matrix retention before and after decellularization. The microcarriers were characterized by scanning electron microscopy and CCK-8 assay. Cartilage-derived microtissues were constructed by combining cartilage-derived microcarriers with human adipose mesenchymal stem cells through three-dimensional static culture and three-dimensional dynamic culture methods. The cell viability and chondrogenic ability of the two groups of microtissues were detected by scanning electron microscopy, live and dead staining, and RT-qPCR. RESULTS AND CONCLUSION: (1) Cartilage-derived microcarriers were successfully prepared. Compared with before decellularization, the DNA content significantly decreased after decellularization (P < 0.001). Scanning electron microscope observation showed that the surface of the microcarrier was surrounded by collagen, maintaining the characteristics of the natural extracellular matrix of cartilage cells. CCK-8 assay indicated that microcarriers had no cytotoxicity and could promote cell proliferation. (2) Scanning electron microscopy and live and dead staining results showed that compared with the threedimensional static group, the three-dimensional dynamic group had a more extended morphology of microtissue cells, and extensive connections between cells and cells, between cells and matrix, and between matrix. (3) The results of RT-qPCR showed that the expressions of SOX9, proteoglycan, and type II collagen in microtissues of both groups were increased at 7 or 14 days. The relative expression levels of each gene in the three-dimensional dynamic group were significantly higher than those in the three-dimensional static group at 14 days (P < 0.05). At 21 days, the three-dimensional static group had significantly higher gene expression compared with the three-diomensional dynamic group (P < 0.001). (4) The results showed that compared with three-dimensional static culture microtissue, three-dimensional dynamic culture microtissue could achieve higher expression of chondrogen-related genes in a shorter time, showing better cell viability and chondrogenic ability. [ABSTRACT FROM AUTHOR]

In recent years, 3D bioprinting technology has developed rapidly, becoming an essential tool in the fields of cancer research, tissue engineering, disease modeling and mechanistic studies. This paper reviewed the fundamental principles of bioprinting technology and its current applications in cancer research and tissue engineering. Bioprinting is an additive manufacturing technology that constructs complex three-dimensional tissue structures by digitally controlling the layer-by-layer deposition of biomaterials and living cells. The core steps of bioprinting include designing a 3D model, selecting appropriate bioprinting techniques and materials, printing layer by layer, followed by post-processing involving cell culture and functionalization. In cancer research, 3D bioprinting can create complex tumor models that simulate the tumor microenvironment, revealing new mechanisms of tumor initiation and progression. Traditional in vitro models, such as 2D cell cultures or animal models, often fail to accurately replicate the complexity of human tumors. However, 3D bioprinted tumor models, which mimic the dynamic interactions between tumor cells and their environment such as immune cells, stroma and blood vessels, offer a more biomimetic platform for studying tumor growth, invasion and metastasis. These models provide a research platform that closely mirrors actual tumor behavior. Additionally, Bioprinted models and scaffolds can be leveraged in personalized precision therapies by efficiently constructing patient-specific 3D models from their own cells. These models enable the prediction of patient’s sensitivity to drugs and radiotherapy. Additionally, localized scaffolds can be developed to meet individual patient needs, allowing for the formulation of appropriate drug types and dosages. Furthermore, 3D-printed scaffolds can support drug delivery by targeting specific areas, reducing drug-related side effects. They can also be used to facilitate local immunotherapy, cytokine therapy, cancer vaccines, and chimeric antigen receptor cell therapy, enhancing therapeutic outcomes. In tissue engineering, traditional tissue repair methods often struggle to address the complex requirements of constructing intricate tissue structures. 3D bioprinting offers a novel solution by enabling the creation of complex tissue architectures and promoting tissue regeneration. Basic tissues, such as bone, cartilage and skin, which have higher regenerative capacities, are gradually being incorporated into clinical practice. Significant progress has also been made in the repair and reconstruction of more complex organs like the liver and heart, though considerable challenges remain before these advancements can be fully translated into clinical applications. Finally, this paper discussed the current challenges and future directions of 3D bioprinting in these fields, aiming to provide reference for researchers. [ABSTRACT FROM AUTHOR]

Vaginal defects cause immense physical and psychological stress to patients. Traditional vaginal reconstruction methods can partially restore physiological function but are often associated with long treatment periods and complications. With the advancement of tissue engineering technology, its application in vaginal reconstruction has shown significant advantages and potential in addressing female reproductive system defects.This article analyzes recent research progress in the field of tissue engineering for vaginal reconstruction,exploring the prospects of seed cells,biomaterials,signaling factors,and animal models to provide inspiration and references for clinical vaginal repair.

Cementum plays a crucial role in linking periodontal and dental tissues and maintaining tooth root stability. Regenerating cementum is essential for functional periodontal tissue regeneration. It is a significant focus in tissue engineering. Periodontal disease, prevalent among the middle-aged and elderly, can severely impact overall health. Effective periodontal tissue regeneration is vital for enhancing the elderly's health and quality of life. Despite the progress, the lack of ideal scaffold materials and methods makes cementum regeneration a persistent challenge. This review discusses the current state of cementum tissue engineering materials and addresses existing challenges, providing a foundation for future scaffold material development.

BACKGROUND: Scholars at home and abroad consider New Zealand rabbits to be an ideal model animal because of the similar anatomical morphology of the lumbar spine to that of the human lumbar spine. There is a lack of systematic comparison of different ways to establish rabbit intervertebral disc degeneration models under X-ray guidance. OBJECTIVE: To establish a rabbit model of lumbar disc degeneration using X-ray guided acupuncture, end-plate injection and combined method, and to compare the modeling effects of these three methods. METHODS: Eighteen 6-month-old New Zealand white rabbits were randomly selected and divided into four groups: acupuncture group, endplate injection group, combined group and blank control group. In the acupuncture group, three consecutive segments of the intervertebral discs (L2/3, L3/4, L4/5) were needled and modeled; in the endplate injection group, 50 μL of anhydrous ethanol was injected at a single point on the endplates of the three consecutive segmental discs; in the combined group, three consecutive segmental intervertebral discs were needled and injected with 50 μL of anhydrous ethanol at four azimuthal points on the endplates of the corresponding segmental discs; and the blank control group received no interventions. X-ray examination was performed to measure the disc height index at 2, 4, and 8 weeks after surgery. The intervertebral disc tissues were then taken for anatomical observation and pathological examination. RESULTS AND CONCLUSION: (1) Anatomical examination showed that fibrous annulus rupture, nucleus pulposus degeneration, and total disc structure disorder were the main manifestation in the acupuncture group, endplate injection group, and combined group, respectively. (2) X-ray examination showed that the disc height index showed the most obvious reduction in the acupuncture group at 2 weeks after operation, significant reductions in the endplate injection group at 2 and 4 weeks after operation, and significant reductions in the combined group at 2, 4, and 8 weeks after operation. (3) Pathological examination showed that the fibrous ring structure was damaged and the inner annulus fibrosus protruded inward in the acupuncture group; endplate fissure, disordered arrangement and nucleus loss were observed in the endplate injection group; total disc structure disorder with the nucleus pulposus losing water and shrinking and no obvious border with the broken annulus fibrosus was found in the combined group. To conclude, acupuncture, endplate injection and the modified endplate injection method can establish the rabbit intervertebral disc degeneration model. Compared with the single method, the modified endplate injection method can greatly accelerate and aggravate the degeneration of the intervertebral disc, and can effectively shorten the experiment period. [ABSTRACT FROM AUTHOR]

BACKGROUND: The regulation of M1/M2 polarization direction of macrophages is particularly critical in tissue engineering applications, and timely regulation can minimize proinflammatory, anti-inflammatory, or tissue healing responses. OBJECTIVE: To implant lentivirus-mediated miRNA-378a macrophage strain complex collagen to detect the expression level of immune regulation in the in vivo environment, and further clarify the influence of miRNA-378a in promoting macrophage M2 polarization in immune regulation and tissue repair in the in vivo environment. METHODS: Lentivirus-mediated miRNA-378a overexpressing macrophage cell lines and negative control virus macrophage lines were amplified and screened, and the macrophage lines were recovered and cultured together with collagen sponge to form a composite scaffold, which was divided into the following groups: (1) Positive group: miRNA-378a overexpressing macrophage-collagen sponge composite; (2) negative group: negative control of virus-mediated miRNA-378a macrophage-collagen sponge composite; (3) control group: macrophage-collagen sponge; (4) blank control group: collagen sponge. The cell density, phenotype, and adhesion of each group were observed by immunofluorescence and scanning electron microscopy. The cells were implanted into the subcutaneous model of the back of mice, and the mice were sacrificed 4 and 7 days after modeling. The direction of macrophage polarization in the collagen sponge composite of macrophages with miRNA-378a overexpression mediated by lentivirus and its effect on immune regulation and tissue repair were analyzed by gross observation, hematoxylin-eosin staining, MASSON staining, and immunohistochemistry. RESULTS AND CONCLUSION: (1) Under immunofluorescence microscopy, the macrophage cell lines in each group were observed to form a composite scaffold with the collagen sponge. (2) Under scanning electron microscope, lentivirus-mediated miRNA-378a macrophages in the positive group proliferated in cell density, had spherical, elliptic and polygonal differentiation, and had more pseudofeet than other groups. (3) Under general observation, the overall 7-day healing was better than that at 4 days. Lentivirus-mediated miRNA-378a macrophages in the positive group healed better than other groups regardless of 4 and 7 days. (4) Lentivirus-mediated miRNA-378a macrophages in the positive group under hematoxylin-eosin staining and MASSON staining had more amounts of fibrocytes, capillaries, fibroblasts, and collagen fiber hyperplasia. (5) Immunohistochemistry showed that lentivirus-mediated miRNA-378a macrophages in the positive group were more positive in 4- and 7-day M2 polarized cells than in other groups. The macrophages of the control and negative groups in 4- and 7-day M2 polarized cells were greater than that of the blank control group. There was no statistical difference between the control group and the negative group. The number of stained cells in the positive, negative, and control groups regardless of 4 and 7 days was higher than that in the blank control group, and the positive group > negative group ≈ control group > blank control group. (6) It is concluded that macrophages with miRNA-378a overexpression have a large amount of fibroblasts, capillaries, fibroblasts, and collagen fiber hyperplasia in vivo, which has a positive effect on tissue repair, and can promote the polarization of macrophages towards M2 type and inhibit the polarization of M1 type, thus contributing to reducing the inflammatory response of the body. [ABSTRACT FROM AUTHOR]

BACKGROUND: Research on carbon nanomaterials in the biomedical field is booming, and related scientific research results are increasing year by year. However, visualization analysis of the annual number of publications, the research status of countries, institutions, authors, and research hotspots and trends in this field is relatively scarce. OBJECTIVE: To present the research status of carbon nanomaterials in biomedical field, reveal the main research subjects, explore the research hotspots and development trends, and provide a reference for the future development of this field. METHODS: The core data set of Web of Science was used as the literature source to search the relevant researches on carbon nanomaterials in the biomedical field from 2012 to 2023. The knowledge map was generated by using Citespace software with countries, institutions, authors, keywords, and co-citations as nodes and for visualization analysis. RESULTS AND CONCLUSION: (1) A total of 2 932 papers were included in this study. In the medical field, carbon nanomaterials had a large number of papers and a fast growth rate. The United States has a large number of papers; China is an emerging force in this field, although the number of papers is the largest, but the level of research and influence need to be improved. The Chinese Academy of Sciences is the largest cooperative network institution, which mainly targets domestic institutions and lacks cooperation with well-known foreign institutions. (2) Keyword analysis displays that the green synthesis method and application of displaying carbon points have been the focus of research, followed by the new method of combining carbon nanomaterials with cancer phototherapy and immunotherapy, the key direction of future research. (3) The dynamic development trend of co-citations suggests that tissue engineering is a hot research topic of carbon nanomaterials in the field of biomedicine, mainly including the research of carbon nanomaterials for the repair and regeneration of heart and nerve tissue and as a bio-ink additive for 3D and 4D bioprinting. (4) In the future, with the development of the biomedical field in the direction of precision and treatment, researchers should speed up the creation of carbon-based systems formed by the combination of scientific and effective carbon nanomaterials with science and technology, new polymers or organic molecules, and new therapeutic methods, so as to give full play to the maximum effect of carbon nanomaterials. [ABSTRACT FROM AUTHOR]

BACKGROUND: Polylactic acid (PLA) has good biocompatibility and a controllable degradation rate and is currently widely used in biomedical engineering. However, PLA has shortcomings such as low mechanical strength and insufficient biological activity, which limits its further application in bone tissue engineering. OBJECTIVE: To construct polylactic acid/polydopamine/tantalum (PLA/PDA/Ta) bone tissue engineering scaffolds, and explore their biosafety and in vitro osteogenesis. METHODS: A PLA scaffold with a porous structure was prepared through liquid crystal display light-curing technology. PLA/PDA scaffolds and PLA/PDA/Ta scaffolds were prepared by soaking PLA scaffolds in dopamine solution and dopamine-tantalum nanoparticle solution, respectively. The microstructure and water contact angle of scaffolds were characterized. MC3T3-E1 cells were co-cultured with PLA, PLA/PDA, and PLA/PDA/Ta scaffolds, respectively, and CCK-8 assay and live/dead cell staining were performed. After osteogenic differentiation, alkaline phosphatase, alizarin red staining, and osteogenic gene detection were performed. RESULTS AND CONCLUSION: (1) The scanning electron microscope results exhibited that the three kinds of prepared scaffolds had an interconnected porous three-dimensional structure, and the average pore diameter was 200 μm. The water contact angle of PLA/PDA/Ta scaffolds was lower than that of PLA and PLA/ PDA scaffolds (P < 0.05). (2) CCK-8 assay showed that compared with PLA and PLA/PDA scaffolds, PLA/PDA/Ta scaffolds could promote cell proliferation (P < 0.05). Live/dead cell staining showed good cell proliferation in the three groups. (3) Alkaline phosphatase and alizarin red staining showed that compared with PLA and PLA/PDA scaffolds, PLA/PDA/Ta scaffolds could promote the expression of alkaline phosphatase and the formation of mineralized nodules. RT-qPCR showed that compared with PLA and PLA/PDA scaffolds, PLA/PDA/Ta scaffolds could enhance the mRNA expression of cell bone morphogenetic protein, Runx- 2, and type I collagen (P < 0.05, P < 0.01). (4) The results showed that the PLA/PDA/Ta scaffold had excellent osteogenic activity and the ability to promote cell proliferation. [ABSTRACT FROM AUTHOR]

BACKGROUND: The in vitro construction of intestinal smooth muscle layer, as an important component of the intestinal wall, has attracted much attention in the bionic construction of tissue-engineered intestinal canal. OBJECTIVE: To explore the effects of cyclic mechanical stretching on the growth activity of intestinal smooth muscle cells and the expression of functional genes within collagen strips. METHODS: The collagen band culture system of intestinal smooth muscle cells was constructed using a self-designed collagen strip stretching culture device with self-made rat tail collagen as a scaffold and primary rat intestinal smooth muscle cells as seed cells. EthD-1/Calcein-AM cell activity staining, magenta staining, cytoskeleton-Ki67 immunofluorescence staining were used to observe the growth activity and proliferation of the cells, and quantitative RT-PCR was used to detect the expression of desmin, α-sma, and vimentin functional genes. RESULTS AND CONCLUSION: The collagen band culture system of intestinal smooth muscle cells was successfully constructed, and intestinal smooth muscle cells in the band had good cell activity. The number of Ki67 positive cells increased and desmin, α-sma and vimentin were significantly overexpressed under cyclic stretching and dynamic culture conditions (P < 0.001). To conclude, mechanical stimulation is beneficial to maintain the growth phenotype of smooth muscle cells and promote their functional differentiation during three-dimensional culture in vitro. [ABSTRACT FROM AUTHOR]

BACKGROUND: The etiology of osteoarthritis is varied and its pathogenesis is still unclear. As bioinformatics has been deepening in recent years, increasing studies have found that the aberrant expression of long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) in joint tissues may mediate the downstream signaling pathways involved in the development of osteoarthritis. OBJECTIVE: To review the mechanism of lncRNA in the development of osteoarthritis and the therapeutic effects of monomers and active compounds derived from traditional Chinese medicine that modulate lncRNA and downstream signaling pathways in osteoarthritis. METHODS: We searched CNKI, WanFang, VIP, and PubMed using the search terms of “long non-coding RNA, knee osteoarthritis, miRNA, chondrocytes, signaling pathway, and traditional Chinese medicine” in Chinese and English, respectively. The search time was from the inception of each database to March 2023. A total of 61 articles were included according to the inclusion and exclusion criteria. RESULTS AND CONCLUSION: The pathogenesis of knee osteoarthritis involves a complex molecular regulatory network, including aberrant expression of lncRNAs and miRNAs in cartilage tissues, which may lead to apoptosis of chondrocytes, degradation of cartilage extracellular matrix, and production of large amounts of pro-inflammatory cytokines. These changes interact with each other to cause degeneration of articular cartilage and progression of osteoarthritis. Therefore, further in-depth studies are needed to reveal the fine mechanisms of the molecular regulatory network. The mechanism of traditional Chinese medicine in the treatment of osteoarthritis mainly focuses on regulating the expression of lncRNA and miRNA, thereby alleviating chondrocyte apoptosis and extracellular matrix degradation, promoting cell proliferation, and slowing down the development of osteoarthritis. [ABSTRACT FROM AUTHOR]

Objective To prepare composite scaffolds for rat H9C2 cardiomyocytes, and to optimize the scaffolds that facilitate the growth of H9C2 cardiomyocytes. Methods The electrospinning method was used to prepare three types of compo-site scaffolds, i.e., polycaprolactone (PCL)/chitosan (CS) scaffold (scaffold A), PCL/CS/zinc oxide (ZnO) scaffold (scaffold B), and PCL/CS/ZnO/carbon nanotubes (CNTs) scaffold (scaffold C), and the preparation of scaffolds was verified by the methods including X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric (TG) analysis, and Raman spectroscopy. Electron microscopy and tensile stress, water contact angle, conductivity, and expansion rate tests were used to eva-luate the physical and chemical properties of the three types of scaffolds, and DAPI staining, electron microscopy, and CCK-8 assay were used to evaluate the biocompatibility of the three types of scaffolds. Results XRD, FTIR spectroscopy, TG analysis, and Raman spectroscopy showed that the three types of scaffolds were successfully prepared. Electron microscopy showed that scaffold C had a significantly longer fiber diameter than scaffold A (F=73.050,t=8.724,9.747,P

Gingival mesenchymal stem cells(GMSCs)are a population of mesenchymal stem cells found in the lamina propria of gingival tissue and can be isolated not only from healthy gingival tissue but also from hyperplastic or even inflamed gingival tissue. GMSCs have become a hot topic of research in oral disease treatment because of their abundant sources, easy availability, unique immunomodulatory properties and multi-directional differentiation potential. GMSCs have been used in the treatment of periodontitis, gingival recession, oral cancer, mandibular defects, peripheral nerve injury repair and so on. To prevent and treat oral diseases, this study will review the recent progress of research on the application of GMSCs in oral diseases.

BACKGROUND: Pulp regeneration has been a hot and difficult research topic in recent years, and the construction of composite bio-scaffolding materials provides new ideas and methods for pulp regeneration. OBJECTIVE: To observe the effect of freeze-dried gelatin modified by methacrylic anhydride/treated dentin matrix bioactive scaffolds on proliferation, migration, and osteogenic differentiation of human dental pulp stem cells. METHODS: The mass ratios of gelatin modified by methacrylic anhydride and treated dentin matrix at 2:1, 1:1 and 1:2 were obtained by dispersing different masses of treated dentin matrix into gelatin modified by methacrylic anhydride solution. The gelatin modified by methacrylic anhydride/treated dentin matrix bioactive scaffolds were prepared by vacuum freeze-drying. The microstructure, water absorption, and mechanical properties of the scaffolds were measured. Human dental pulp stem cells were cultured with different mass ratios of scaffold extract and DMEM (control group) to detect cell proliferation and migration. Human dental pulp stem cells were cultured with different mass ratios of scaffold extract + osteogenic induction solution and DMEM + osteogenic induction solution (control group), and their osteogenic ability was analyzed by alkaline phosphatase staining. RESULTS AND CONCLUSION: (1) Under scanning electron microscopy, the scaffolds of the three groups all had porous structures. The porosity of the scaffolds increased with the increase of treated dentin matrix quality, and there was significant difference between the two groups (P < 0.05). The water absorption of scaffolds increased with the increase of treated dentin matrix mass, and there was significant difference between groups (P < 0.05). The compressive strength and shear strength of the scaffold increased with the increase of the mass of treated dentin matrix. (2) CCK-8 assay showed that after 3, 5, and 7 days of culture, the cell proliferation absorbance values in the 2:1, 1:1, and 1:2 scaffold groups were higher than those in the control group (P < 0.05). The cell proliferation absorbance values increased with the increase of treated dentin matrix mass in the scaffold (P < 0.05). The cell scratch test showed that the cell migration rate in the 2:1, 1:1, and 1:2 scaffold groups was higher than that in the control group (P < 0.05), and the cell migration rate increased with the increase of treated dentin matrix mass in the scaffold (P < 0.05). (3) Alkaline phosphatase staining showed that the osteogenic differentiation ability of cells in the 2:1, 1:1, and 1:2 scaffold groups was stronger than that in the control group, and the osteogenic ability of cells was enhanced with the increase of treated dentin matrix mass in the scaffold. (4) The results showed that the scaffold with a mass ratio of 1:2 between gelatin modified by methacrylic anhydride and treated dentin matrix was the most suitable for the proliferation and differentiation of dental pulp stem cells. [ABSTRACT FROM AUTHOR]

BACKGROUND: Due to the mechanical properties, unstable drug release, single function and other problems of pure hydrogel materials, in recent years, researchers have prepared a variety of metal organic frameworks-based hydrogel materials by introducing metal organic frameworks into hydrogel, and showed great potential in the field of soft and hard tissue regeneration. OBJECTIVE: To classify the metal organic frameworks-based hydrogel materials based on how metal organic frameworks enhance the properties of hydrogel and further summarize its recent research in the field of soft and hard tissue regeneration, in order to provide ideas and theoretical supports for the subsequent in-depth research on synthesis mechanism and clinical application of the composite material. METHODS: Using “metal organic frameworks, hydrogels, tissue engineering, tissue, bone regeneration, bone, wound” as English and Chinese search terms, we searched Web of Science, PubMed, CNKI, and Wanfang databases. The search period ranged from January 2000 to August 2023. By reading the titles and abstracts, the repetitive studies and unrelated literature of Chinese and English literature were excluded. After the literature quality evaluation, 73 articles were included for review. RESULTS AND CONCLUSION: (1) Metal organic frameworks-based hydrogel materials effectively solve the problems of poor mechanical properties, unstable drug release and single function of pure hydrogel. (2) Metal organic frameworks enhance the capacity of repair and regeneration by strengthening the crosslinking of hydrogel, the drug delivery capacity of hydrogel and the multifunction of hydrogel. (3) In terms of hard tissue repair, it has shown good repair effects in animal models of diseases such as bone defects, osteoarthritis, and cartilage defects, suggesting potential application prospects in clinical repair. (4) In terms of soft tissue regeneration, it has the capacities of hemostasis, antibacterial, inflammatory state regulation, oxidative stress state regulation, promoting angiogenesis and other functions, effectively improving the microenvironment of various complex wounds and promoting soft tissue regeneration. (5) Although metal organic frameworks-based hydrogels have many excellent properties, they are still in the initial stage and there are some urgent problems to be solved in the process of clinical transformation, such as the cytotoxicity of metal organic frameworks and large-scale synthesis of metal organic frameworks. (6) With further research, metal organic frameworks-based hydrogels have broad application prospects in the field of soft and hard tissue repair. [ABSTRACT FROM AUTHOR]

BACKGROUND: A large number of studies have confirmed that tissue engineering scaffolds can almost completely repair osteochondral defects. However, when osteochondral defects are complicated with infection, even after thorough debridement in the early stage, the repair effect of simple osteochondral tissue engineering scaffolds is often unsatisfactory. OBJECTIVE: To prepare fibroin/chitosan/nano-hydroxyapatite scaffold loaded with vancomycin hydrochloride sustained release microspheres, and to investigate the repair effect on infected osteochondral defect in distal femur of rabbit. METHODS: (1) Vancomycin hydrochloride sustained release microspheres were prepared by emulsified solvent evaporation method. The sustained-release microspheres of different weights (7.5, 10, and 12.5 mg) were mixed with fibroin protein-chitosan nanohydroxyapatite solution, and the scaffolds of fibroin protein/chitosan/nano-hydroxyapatite were prepared by chemical crosslinking method. The porosity, water absorption and expansion rate, hot water loss rate of the scaffolds, and drug sustained-release in vitro were characterized. (2) Forty-five New Zealand white rabbits were randomly divided into blank group, control group, and experimental group, with 15 rabbits in each group. The osteochondral defect and infection model of the distal femur of the right hind limb was established in both groups. The blank group was not treated, and the control group was implanted with fibroin protein-chitosan-nano-hydroxyapatite scaffold. Vancomycin hydrochloride sustained-release microspheres (10 mg) of fibroin/chitosan/nano-hydroxyapatite scaffold were implanted in the defect of the experimental group. The levels of C-reactive protein and leukocytes in blood samples were detected 1 week after operation. At 4, 8 and 12 weeks after operation, the tissue of the operative area was taken for gross observation and pathological observation. RESULTS AND CONCLUSION: (1) With the increase of sustained-release microspheres content, the porosity of scaffolds decreased, and there was significant difference among groups (P < 0.05). There were no significant differences in the pore size, water absorption expansion rate and hot water loss rate among the three groups (P > 0.05). Vancomycin hydrochloride was released sustainably in vitro for more than 30 days in all three groups of scaffolds. (2) The levels of C-reactive protein and leukocytes in blood samples of the experimental group were lower than those of the blank group and control group (P < 0.05). The repair of gross cartilage in the experimental group was significantly better than that in the blank group and the control group. Hematoxylin-eosin, Masson, Alcian blue and type II collagen immunohistochemical stainings showed that the osteochondral repair effect of the experimental group was significantly better than that of the blank group and the control group at each time point. (3) The results showed that fibroin/chitosan/nano-hydroxyapatite scaffolds loaded with vancomycin hydrochloride sustained-release microspheres could effectively promote the repair of open osteochondral defects. [ABSTRACT FROM AUTHOR]

BACKGROUND: As tissue engineering brings new hope to the worldwide problem of articular cartilage repair, the construction of light-curing 3D printed hydrogel scaffolds with biomimetic composition is of great significance for cartilage tissue engineering. OBJECTIVE: To construct a biomimetic methacryloylated hyaluronic acid/acellular Wharton’s jelly composite hydrogel scaffold by digital light processing 3D printing technology, and to evaluate its biocompatibility. METHODS: Wharton’s jelly was isolated and extracted from human umbilical cord, then decellulated, freeze-dried, ground into powder, and dissolved in PBS to prepare 50 g/L acellular Wharton’s jelly solution. Methylallylated hyaluronic acid was prepared, lyophilized and dissolved in PBS to prepare 50 g/L methylallylated hyaluronic acid solution. Acellular Wharton’s jelly solution was mixed with methacrylyacylated hyaluronic acid solution at a volume ratio of 1:1, and was used as bio-ink after adding photoinitiator. Methylacrylylated hyaluronic acid hydrogel scaffolds (labeled as HAMA hydrogel scaffolds) and methylacrylylated hyaluronic acid/acellular Wharton’s jelly gel scaffolds (labeled as HAMA/WJ hydrogel scaffolds) were prepared by digital light processing 3D printing technology, and the microstructure, swelling performance, biocompatibility, and cartilage differentiation performance of the scaffolds were characterized. RESULTS AND CONCLUSION: (1) Under scanning electron microscope, the two groups of scaffolds showed a three-dimensional network structure, and the fiber connection of HAMA/WJ hydrogel scaffold was more uniform. Both groups achieved swelling equilibrium within 10 hours, and the equilibrium swelling ratio of HAMA/WJ hydrogel scaffold was lower than that of HAMA hydrogel scaffold (P < 0.05). (2) CCK-8 assay showed that HAMA/WJ hydrogel scaffold could promote the proliferation of bone marrow mesenchymal stem cells compared with HAMA hydrogel scaffold. Dead/live staining showed that bone marrow mesenchymal stem cells grew well on the two groups of scaffolds, and the cells on the HAMA/WJ hydrogel scaffolds were evenly distributed and more cells were found. Phalloidine staining showed better adhesion and spread of bone marrow mesenchymal stem cells in HAMA/WJ hydrogel scaffold than in HAMA. (3) Bone marrow mesenchymal stem cells were inoculated into the two groups for chondrogenic induction culture. The results of qRT-PCR showed that the mRNA expressions of agglutinoglycan, SOX9 and type II collagen in the HAMA/WJ hydrogel scaffold group were higher than those in the HAMA hydrogel scaffold group (P < 0.05, P < 0.01). (4) These findings indicate that the digital light processing 3D bioprinting HAMA/WJ hydrogel scaffold can promote the proliferation, adhesion, and chondrogenic differentiation of bone marrow mesenchymal stem cells. [ABSTRACT FROM AUTHOR]

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BACKGROUND: Long non-coding RNAs (lncRNAs), as important regulators of the inflammatory response, are involved in the immune-inflammation-brain crosstalk mechanism after ischemic stroke and have the potential to become a therapeutic agent for neurological dysfunction after ischemic stroke. OBJECTIVE: To analyze and summarize the molecular mechanism of lncRNA acting on glial cells involved in the neuroimmuno-inflammatory cascade response after ischemic stroke and the associated signaling pathways, pointing out that lncRNAs have the potential to regulate inflammation after ischemic stroke. METHODS: PubMed was searched using the search terms of “ischemic stroke, long non-coding RNA, neuroinflammation, immune function, signal pathway, microglia, astrocytes, oligodendrocyte, mechanism,” and 63 relevant documents were finally included for review. RESULTS AND CONCLUSION: In the early stage of ischemic stroke, the death of nerve cells due to ischemia and hypoxia activates the innate immune response of the brain, promoting the secretion of inflammatory factors and inducing blood-brain barrier damage and a series of inflammatory cascades responses. As an important pathogenesis factor in ischemic stroke, the neuroimmuno-inflammatory cascade has been proved to seriously affect the prognosis of patients with ischemic stroke, and it needs to be suppressed promptly in the early stage. Neuroinflammation after ischemic stroke usually induces abnormal expression of a large number of lncRNAs that mediate a series of neuro-immune-inflammatory crosstalk mechanisms through regulating the polarization of microglia, astrocytes and oligodendrocytes to exert post-stroke neuroprotective effects. LncRNAs, as important regulatory factors of the inflammatory response, inhibit the neuroimmuno-inflammatory cascade response after ischemic stroke through regulating nuclear factor-κB, lncRNA-miRNA-mRNA axis, Rho-ROCK, MAPK, AKT, ERK and other signaling pathways to effectively improve neurological impairment after ischemic stroke. Most of experimental studies on the interaction between lncRNAs and ischemic stroke are based on a middle cerebral artery occlusion model or a cerebral ischemia-reperfusion injury model, but no clinical trials have been conducted. Therefore, it remains to be further explored about whether lncRNAs can be safely applied in clinical practice. At present, there are many therapeutic drugs for the treatment of ischemic stroke, but there are relatively few studies on the application of lncRNAs, exosomes and other transplantation technologies for the treatment of ischemic stroke using tissue engineering technology, which need to be further explored. lncRNA has become an important target for the treatment of ischemic stroke with its relative stability and high specificity. In future studies, more types of inflammatory lncRNAs that function under ischemic-hypoxia conditions should continue to be explored, in order to provide new research directions for the treatment of neuroinflammation after ischemic stroke. [ABSTRACT FROM AUTHOR]

BACKGROUND: With the proven ability of traditional Chinese medicine such as icariin and berberine to promote bone regeneration by regulating various mechanisms and targets, researchers have combined active ingredients of traditional Chinese medicine with bone tissue engineering and found that they have unique advantages in treating bone defects. OBJECTIVE: Starting from the active ingredients of traditional Chinese medicines that promote bone formation, to screen cases of their effective combination with different drug-carrying scaffold materials, and summarize the active ingredients of traditional Chinese medicines that have the potential to be applied to bone tissue engineering. METHODS: CNKI, WanFang, PubMed, and Web of Science were searched for relevant literature published from 2000 to 2023, using the keywords of “bone tissue engineering, bone tissue-engineered scaffold materials, bone defect, bone repair, bone regeneration, traditional Chinese medicine” in Chinese and English. According to the inclusion and exclusion criteria, 87 papers were finally included for review. RESULTS AND CONCLUSION: There are various kinds of active ingredients of traditional Chinese medicine to promote bone regeneration, mainly including flavonoids, non-flavonoid polyphenols, alkaloids, glycosides. These active ingredients have anti-inflammatory and analgesic effects, promote osteoblasts, inhibit osteoclasts and promote early angiogenesis. The combination of active ingredients of traditional Chinese medicine with bone tissue engineering is effective in anti-inflammation, accelerating collagen and bone formation, and promoting the expression of osteogenic genes, which provides a theoretical basis for the application of traditional Chinese medicine in bone tissue regeneration, and at the same time provides a new idea for the repair of bone defects. [ABSTRACT FROM AUTHOR]

Recombinant collagen is a biopolymer with broad potential applications in various fields, such as biomedicine and tissue engineering. The triple-helix structure of collagen imparts unique biological functions and biocompatibilit but also increases the complexity of its expression in microbial systems. In this study, bacterial collagen V-B was used as a model protein to promote the expression of recombinant collagen in Corynebacterium glutamicum through optimization of expression elements. Firstly, the most efficient promoter tac-R0 was obtained through promoter screening and fermentation duration optimization. Subsequently, the RBS calculator was used to design a mutation library for ribosome binding sites (RBS) and aligned spacing (AS). The RBS and AS with the highest strength were identified, which increased the yield of V-B to 514 mg/L. Furthermore, through the tandem combination of multi-gene expression cassettes, the final yield of V-B increased by 8.4-fold compared to the initial level, reaching 697 mg/L. This study lays a foundation for the industrial production of recombinant collagen. [ABSTRACT FROM AUTHOR]

BACKGROUND: Exosomes play a role in all stages of wound repair, and there is currently a large body of research on exosomes in skin wound repair, which has been shown to have great potential for clinical applications. OBJECTIVE: To summarize and discuss the main mechanisms and clinical applications of exosomes in the treatment of skin wounds, in order to promote the clinical translation of exosomes. METHODS: PubMed, clinicaltrials.gov, China National Knowledge Infrastructure, Food and Drug Administration database, and Chinese Clinical Trial Register were searched from inception to March 2023. The English search terms were “exosomes, wound healing, stem cells, chronic wound, immunoregulation, inflammation, skin, therapeutic use, isolation, characterization, infections”. The Chinese search terms were “exosomes, wound healing, stem cells, immunomodulation, clinical applications”. A total of 79 articles were included for the summary. RESULTS AND CONCLUSION: (1) Exosomes can improve and accelerate wound healing through inflammation regulation, immune protection, angiogenesis, cell proliferation and migration, and collagen remodeling. (2) Exosomes derived from stem cells have mature preparation techniques and related mechanism research, which is currently the mainstream research direction. Non-stem cell-derived exosomes have the advantages of convenience, economy, and easy production, and can be used as a supplement for clinical applications. (3) The clinical application of exosomes is still in its infancy, but has great potential for application. Various exosome modification techniques have laid the foundation for the future development of clinically personalized services and require further research. (4) The clinical translation of exosomes faces many challenges, such as low yield, high heterogeneity, lack of unified standards for isolation, purification, and quality control, and difficulties in storage. [ABSTRACT FROM AUTHOR]

BACKGROUND: In recent years, some scholars in the field of tendon bone injury have attached stromal cell-derived factor 1 to tissue engineering scaffolds to promote tendon bone healing, and achieved good results. However, whether stromal cell-derived factor 1 promotes tendon bone healing mechanisms and participates in the repair of natural healing has not yet been defined. OBJECTIVE: To study the expression of stroma-cell derived factor 1 during tendon bone healing after rupture of the whole supraspinatus muscle of the rabbit rotator cuff and its migration effect and optimal in vitro migration promoting concentration on stem cells during tendon bone injury. METHODS: Totally 18 adult New Zealand rabbits were randomly selected to establish rotator cuff injury models, and an additional 3 rabbits were selected as blank controls. At 3, 5, 7, 14, 21, and 28 days after modeling, three rabbits were executed separately and the rabbits in the blank group were sacrificed. The tissues of tendon bone junction were taken and stored in a -80 ℃ refrigerator. The expression of stromal cell-derived factor 1 was detected by ELISA at each time point after injury. Mesenchymal stem cells were isolated from the bone marrow of young rabbit femur, cultured, and identified. Transwell assay was performed to verify the migration-promoting effect of stromal cell-derived factor 1 on stem cells and the optimal migration-promoting concentration in vitro. The stem cells cultured to P3 were co-cultured with BrdU and injected into the rabbit ear marginal vein, and immunohistochemical staining was used to verify whether the stem cells migrated to the injury site. RESULTS AND CONCLUSION: (1) Stromal cell-derived factor 1 gene expression was bimodal during rotator cuff tendon bone healing. Stromal cell-derived factor 1 gene expression increased significantly at 3 days post-injury (P < 0.01) and then decreased, reaching a minimum at 5 days post-injury. It increased again and reached a peak 14 days after injury (P < 0.01) and then decreased. (2) Cell immunohistochemical staining displayed that stem cells labeled with BrdU did migrate to the injury site. (3) The results of the transwell experiment exhibited that 60-80 ng/mL stromal cell-derived factor 1 had the best effect on promoting migration of stem cells, while a concentration of 200 ng/mL inhibited migration. (4) Stromal cell-derived factor 1 is involved in the healing of rotator cuff tendon bone during the inflammatory response phase and the proliferation phase. The mechanism of action may be to promote the migration of stem cells to the injury and their differentiation into various types of cells to promote repair. In addition, the pro-migration effect of stromal cell-derived factor 1 exists at a range of concentrations, beyond which it may act as an inhibitor. [ABSTRACT FROM AUTHOR]

Sericin a by-product of silk production has good hydrophilicity biodegradability and reactivity because of the rich polar amino acids and loose spatial structure. Sericin also has many biological activities such as anti-oxidation anticoagulation hypoglycemic and promoting cell proliferation and differentiation. Sericin hydrogels formed by self-assembly or crosslinking agent have multiple advantages and are widely used in tissue engineering wound repair drug release and other fields. The construction strategies of sericin hydrogels include physical methods chemical crosslinking ultraviolet photocatalysis and transgenic functional modification. Physical methods are used to construct sericin hydrogels mainly by triggering the polymerization of sericin molecules to generate intermolecular forces to form cross-linked networks. Inducing sericin hydrogels with ultrasound is to use the ultrasonic cavitation phenomenon in solution to act on sericin molecules in aqueous solution cause a more violent collision between molecules and form a more stable and orderly spatial structure by rearrangement so as to obtain a stable gel network structure insoluble in water. Vacuum freeze-drying technology facilitates the physical cross-linking to form a stable and firm spatial network structure using the characteristics of molecular response to ambient temperature changes. Sericin hydrogels prepared by high temperature high pressure and self-assembly method have the advantages of mild reaction conditions and controllable gelation process. Repeated freezing and thawing is a safe and effective method for preparing porous gels. The obtained sericin hydrogels not only have excellent mechanical properties high pore expansion ratio good hydrophilicity and thermal stability but the ability to load and release small molecule drugs and nanoparticles. In addition adding an appropriate concentration of ethanol 15% to the sericin solution can accelerate the gelation process of sericin and enhance the mechanical properties of the gel. Chemical crosslinking promotes the formation of stable covalent bonds between sericin molecules and enables sericin in solution to form a network structure and gelatinize which can not only improve the mechanical properties of sericin hydrogels but also make sericin and other component materials mixed into a multi-functional composite network structure of hydrogels. The stable pure sericin hydrogel or sericin complex gel that can be effectively constructed by using single crosslinking agents such as genipin peroxidase and glutaraldehyde or compound crosslinking agents has been widely used in ischemic myocardial repair therapy skin tissue regeneration and repair tissue engineering scaffolds drug delivery carriers supporting neuronal network development and improving the thermal stability and mechanical properties of cotton fabrics. When chemical agents are used to cross-link sericin hydrogels the crosslinkers with low toxicity few residues or easy removal should be preferentially selected and the cytotoxicity of hydrogels should be evaluated to ensure the further application of hydrogels. In addition to physical and chemical crosslinking methods sericin hydrogels can also constructed by means of ultraviolet photocatalytic crosslinking and transgenic functional modification. UV light can induce free radical polymerization and construct in situ cross-linked transparent porous sericin-based hydrogels. With the use of 3D printing technology sericin-based hydrogel scaffolds with large pore structure can be customized which is conducive to maintaining the wet and clean environment required for wound healing and is an ideal choice for visual wound care. By introducing the coding genes of functional proteins into the genome of silkworms and spinning into the sericin layer of silk sericin biomaterials with various biological functions can be prepared conveniently and economically which strategically avoids sourcing and safety risks from exogenously added functional proteins during materials fabrication. Sericin hydrogels have excellent histocompatibility abundant chemical modification sites high hydrophilicity and controllable degradability. Sericin gels prepared with different construction strategies have been widely used in skin wound dressing nerve regeneration cartilage repair functional drug delivery and other fields. Sericin gels are mainly developed and applied from the directions of improving the mechanical properties of gels avoiding the toxic effects of chemical crosslinking agents and exploring new functions of gel materials so as to obtain greater application value. [ABSTRACT FROM AUTHOR]

Due to the large number of blind individuals and the shortage of donor corneas available for transplantation, artificial corneas have gradually become a research hotspot, However, artificial corneas often experience implant tearing due to insufficient mechanical properties. In order to solve this problem, researchers at home and abroad have tried to improve the mechanical properties of corneal repair materials by a series of research work. This paper summarizes the progress relating to the mechanical properties of four common natural polymer-based corneal repair materials, namely collagen, gelatin, silk fibroin, and chitosan. The results show that physical methods such as photo-crosslinking and thermal crosslinking, chemical methods such as 1(3-dimethylaminopropyl) -3-ethylcarbodiimide (EDC)/N-hydroxysuccinimide (NHS) crosslinking, genipine or glutaraldehyde crosslinking and other composite methods can significantly improve the mechanical properties of corneal materials, but these methods still have some shortcomings. Therefore, further development of high-quality artificial corneas is crucial. It is hoped that the article can provide some reference and ideas for the study of improving the mechanical properties of corneal repair materials through summarization. [ABSTRACT FROM AUTHOR]

BACKGROUND: Electrospun porous nanofiber exhibits excellent properties and designability. It is an effective way to control the release of traditional Chinese medicine and improve the bioavailability to design an advanced drug delivery system, which has a broad application prospect. OBJECTIVE: To review the construction methods of the electrospinning drug delivery system of traditional Chinese medicine and its related research progress in the medical field. METHODS: The literature search was performed in CNKI, PubMed, and Web of Science databases with the search terms “electrospinning, traditional Chinese medicine, drug carrier, drug delivery system, tissue engineering, dressing” in both English and Chinese for articles published from 2013 to 2023. Finally, 62 articles were included in this review. RESULTS AND CONCLUSION: (1) The key elements of the electrospinning drug delivery system of Chinese medicine preparation are substrate material, traditional Chinese medicine composition, and drug loading method. (2) The preparation of the electrospinning drug delivery system of Chinese medicine can be carried out according to the application scenario and therapeutic purpose. Firstly, the types of Chinese medicine are selected, then the polymer matrix and solution suitable for them are selected, and finally, the fiber structure is designed according to the drug release requirements and the appropriate drug loading method is adopted. (3) At present, the medicinal agents used are mainly plant Chinese medicine, and there is a lack of systematic research on animal and mineral Chinese medicine. (4) Blended drug loading is the most studied and applied drug loading method, and its drug release characteristics and adaptation scenarios are constantly expanded by optimizing the physicochemical properties of the solution and selecting the diversity of loaded substances. Multilayer fibers with different compositions and properties can be prepared by coaxial, multi-axis, and sequential electrospinning methods, which have broad development prospects. (5) The early application of the electrospinning drug delivery system of Chinese medicine focused on medical dressings according to the antibacterial and hemostatic functions. In recent years, it has been studied in the field of tissue engineering because some components of traditional Chinese medicine can promote cell adhesion, proliferation, and differentiation. (6) At present, the research mainly focuses on the characterization and optimization of loading materials, processes, physicochemical properties, and biological properties, but the research on the mechanism is less. Its clinical application has not been widespread; the adverse reactions in vivo and the interaction between its degradation behavior and drug release behavior are still unknown. (7) Future studies need to consider: We should expand the application of Chinese medicine by improving the physicochemical properties and increasing the purification of Chinese medicine extracts. We need to comprehensively study the therapeutic effects and application mechanisms of Chinese medicine, and clarify the interaction of degradation behavior and drug release behavior, to achieve a more perfect combination and application of Chinese medicine and electrospinning nanofibers under a more accurate mechanism. [ABSTRACT FROM AUTHOR]

BACKGROUND: Acellular vascular scaffolds can mimic the microstructure and function of native blood vessels, but some extracellular matrix loss occurs during their preparation, which affects their hemocompatibility. Therefore, it is necessary to modify them to improve their hemocompatibility. OBJECTIVE: To assess the hemocompatibility of acellular vascular scaffold prepared by Triton-x100/heparin sodium treatment. METHODS: The abdominal aorta was taken from SD rats and randomly divided into control and experimental groups. The control group was treated with Triton-x100 for 48 hours. The experimental group was treated with Triton-x100 for 48 hours and then treated with heparin sodium. The morphology and hydrophilicity of the two groups of acellular vascular scaffolds were detected. The hemocompatibility of the two groups of acellular vascular scaffold was evaluated by recalcification coagulation time test, platelet adhesion test, dynamic coagulation time test, hemolysis test, and complement activation test. RESULTS AND CONCLUSION: (1) Scanning electron microscopy showed that the surface of the two groups of vascular scaffolds was relatively intact, and a large number of fiber filaments appeared on the surface of the scaffolds after decellularity treatment, and the surface microstructure changed significantly. The water contact angle of the two groups of vascular scaffolds was smaller than that of natural vessels (P < 0.000 1). There was no significant difference in water contact angle between the two groups (P > 0.05). (2) The coagulation time of vascular scaffold was longer in the experimental group than in the control group (P < 0.05). The number of platelets attached to the scaffold membrane was less in the experimental group than that in the control group (P < 0.000 1). The coagulation index was greater in the experimental group than that in the control group (P < 0.01), and the complement level was lower in the experimental group than that in the control group (P < 0.001). The hemolysis rate of the two groups was lower than 5% of the national standard. (3) To conclude, acellular scaffold treated with Triton-x100/heparin sodium has excellent hemocompatibility. [ABSTRACT FROM AUTHOR]

Bone repair is a complex physiological process. The nerves within the bone can regulate bone tissue regeneration through the secretion of bioactive factors and interactions with cells within the bone. Recent studies have sought to leverage the principles of neurovascular coupling in the creation of bioactive materials, yielding promising results. This article reviews nerves and vessels within the bone, the role of neural signals in bone repair, and potential mechanisms of neurovascular coupling in bone repair, expecting to provide a thorough understanding on the function of neurovascular coupling in bone repair as well as fresh perspectives on the scientific research and clinical treatment of bone repair strategies.

The identification of suitable seed cells represents a critical scientific problem to be solved in the field of oral and maxillofacial bone tissue regeneration. The application of adipose-derived stem cells (ASCs) in tissue and organ repair and regeneration has been studied extensively. In recent years, dedifferentiated fat (DFAT) cells have also shown broad application prospects in the field of bone tissue engineering. DFAT cells express stem cell-related markers and have the potential to differentiate into adipocytes, osteoblasts, chondrocytes, nerve cells, cardiomyocytes and endothelial cells. In addition, DFAT cells also have the advantages of minimally invasive acquisition, strong proliferation and high homogeneity. Currently, all studies involving the application of DFAT cells in scaffold-based and scaffold-free bone tissue engineering can confirm their effectiveness in promoting bone regeneration. However, cytological research still faces some challenges, including relatively low cell culture purity, unclear phenotypic characteristics and undefined dedifferentiation mechanisms. It is believed that with the continuous development and improvement of isolation, culture, identification and directional induction of osteogenic differentiation methods, DFAT cells are expected to become excellent seed cells in the field of oral and maxillofacial bone tissue engineering in the future.

BACKGROUND: Tissue engineering is considered an ideal treatment for growth plate regeneration. However, most of the current research on regenerative tissue engineering is the traditional scaffold-based strategy. As the limitations of traditional scaffolds are gradually revealed, the research direction is gradually diversifying. OBJECTIVE: To summarize the application of scaffold-based and scaffold-free strategies in the treatment of growth plate cartilage regeneration and their respective advantages and disadvantages. METHODS: The relevant articles were searched from PubMed, Wiley, and Elsevier. The search terms were “growth plate injury, regeneration, tissue engineering, scaffold, scaffold-free, biomimetic, cartilage” in English. The time was limited from 1990 to 2023. Finally, 104 articles were included for review. RESULTS AND CONCLUSION: The biomimetic strategy is to reduce the cell composition, biological signals and unique mechanical properties of each region to the greatest extent by simulating the unique organizational structure of the growth plate, so as to build a biomimetic microenvironment that can promote tissue regeneration. Therefore, the design of a biomimetic scaffold is to simulate the original growth plate as far as possible in terms of composition, structure and mechanical properties. Although some results have been achieved, there is still the problem of the unstable regeneration effect. The scaffold-free strategy believes that the limitations of scaffolds will have adverse effects on regenerative therapy. Therefore, the design of scaffold-free constructs relies as much as possible on the ability of cells to generate and maintain extracellular matrix without interfering with cell-cell signals or introducing exogenous substances. However, there are some problems, such as poor stability, low mechanical strength and greater difficulty in operation. Biomimetic strategy and scaffoldfree strategy have different emphases, advantages and disadvantages, but they both have positive effects on growth plate cartilage regeneration. Therefore, subsequent studies, whether adopting a biomimetic strategy or a scaffold-free strategy, will focus on the continuous optimization of existing technologies in order to achieve effective growth plate cartilage regeneration therapy. [ABSTRACT FROM AUTHOR]

BACKGROUND: Collagen is a biomedical material with good biocompatibility, low toxicity, low immunoactivity, and high cellular affinity. However, the defects such as hydrophilicity and poor thermal stability are the key technical problems that need to be solved urgently in biomedical, tissue engineering, and other applications. OBJECTIVE: To elaborate on the preparation method, characterization, and application progress of acylated collagen. METHODS: PubMed, X-mol, and CNKI databases were used to search the literature on acylated collagen preparation methods, characterization, and application. The search time was from January 1992 to May 2023. The English search terms were “acylated collagen, modified collagen, water-soluble collagen, acetic anhydride”. Chinese search terms were “acylated collagen, modified collagen, water-soluble collagen”. After an initial screening of all articles according to inclusion and exclusion criteria, 53 articles with high relevance were retained for review. RESULTS AND CONCLUSION: (1) The preparation of acylated collagen is mainly obtained by the acylation reaction of acid anhydride, and the reaction sites are mainly ε-amino and N-terminus-amino of collagen, and the reaction environment of acylation reaction needs to be carried out in an alkaline environment. (2) Succinic anhydride is the preferred reactant of acylated collagen. Carbonic anhydride, citric anhydride, and bifunctional modifiers with acylation ability have been excavated in recent years to meet various requirements, but it is still limited to laboratory preparation; complex preparation process is difficult to industrialize, and follow-up research is needed to continuously improve. (3) The characterization methods of acylated collagen are similar to those of collagen, but there is still a lack of standards for the water-soluble characterization of acylated collagen. (4) In recent years, acylated collagen has been gradually used in the preparation of lenses, hydrogels, and dressings, as well as cosmetic raw materials. However, there is still little research on the application of acylated collagen, and there is a lack of complete in vivo experiments to verify the practicality of acylated collagen. [ABSTRACT FROM AUTHOR]

BACKGROUND: Although nerve conduits provide an effective treatment approach for nerve repair, traditional nerve conduits merely serve as mechanical channels in the repair process. The therapeutic effect still needs to be improved. Carbon nanomaterials have good physicochemical properties and hold great potential in fields such as electrochemistry and tissue engineering. Nerve conduits loaded with carbon nanomaterials, after appropriate functional modifications, are expected to further enhance the quality of nerve repair. OBJECTIVE: To review the recent research progress of carbon nanomaterial-loaded nerve conduits/scaffolds for peripheral nerve repair. METHODS: PubMed, Web of Science, China National Knowledge Infrastructure (CNKI), and Wanfang databases were searched for the literature on the application of carbon nanomaterial catheters in peripheral nerve regeneration. English keywords were “carbon nanomaterials, carbon-based nanomaterials, nerve conduit, nerve guidance conduit, scaffold, nerve regeneration, peripheral nerve repair, peripheral nerve injury” and Chinese keywords were “carbon nanomaterials, carbon materials, graphene, carbon nanotubes, nerve conduits, nerve scaffolds, nerve repair, nerve regeneration, peripheral nerve injury”. Finally, 69 articles were selected for this review. RESULTS AND CONCLUSION: (1) Carbon nanomaterials primarily restore damaged neural bioelectric signal conduction by activating calcium ion channels and inducing intracellular calcium activity. The application of various nerve conduit design strategies has improved the effectiveness of nerve repair. (2) Successful intraneural vascularization is the prerequisite for repairing peripheral nerve injuries. Reactive oxygen species and reactive nitrogen species generated by carbon nanomaterials trigger subsequent signaling pathways that promote intraneural vascularization. (3) The ratio of M1 to M2 macrophages affects the repair of peripheral nerve injuries. Carbon nanomaterials promote the polarization of macrophages into the M2 phenotype, thereby exerting their anti-inflammatory and regenerative effects. (4) Some carbon nanomaterials may induce excessive generation of reactive oxygen species intracellularly, potentially exhibiting cytotoxicity detrimental to nerve repair. However, appropriate functional modifications can improve the adverse effects caused by carbon nanomaterials. (5) Although carbon nanomaterials can restore the microenvironment of peripheral nerve injuries and play a positive role in promoting peripheral nerve regeneration, their inherent cytotoxicity and unclear in vivo degradation pathways still pose challenges for clinical application. However, by employing methods such as functional modification, it is possible to enhance the biocompatibility of carbon nanomaterials. Modified carbon nanomaterials have promising prospects in the field of neural tissue engineering. [ABSTRACT FROM AUTHOR]

BACKGROUND: Biomimetic design of bioactive materials to restore, maintain or improve the function of tissue based on the understanding of anatomy on the function and structure of biological tissue is a research hotspot in the field of regenerative medicine at present. OBJECTIVE: To discuss the effect of mechanical properties, three-dimensional spatial structure, and biochemical activity of biomedical scaffolds on cell behavior and review the application of biomedical scaffolds in the field of tissue engineering. METHODS: The articles published in CNKI, Wanfang, Web of Science, and PubMed databases from January 2003 to April 2023 were searched by computer. The Chinese search terms were “extracellular matrix, tissue engineering, scaffolds, biomaterials, biomimetic structures, mechanical properties, three-dimensional structures, tendon-bone interface, osteochondral, neural conduits, artificial blood vessels”. English search terms were “extracellular matrix, tissue engineering, scaffolds, biomimetic structures, biomaterials, tendon bone interfaces, osteochondral, neural conduits, artificial blood vessels”. RESULTS AND CONCLUSION: Cells are in a complex and dynamic three-dimensional environment, so the extracellular matrix is the ultimate target of biomaterial simulation. The bionic structure of biomedical scaffolders needs to be similar to the real microenvironment, so that cells can stick to the wall, grow and migrate normally, and maintain their diverse physiological functions. Biomimetic design of extracellular matrix in terms of mechanical properties, threedimensional spatial structure, and biochemical properties of biomedical scaffolds can play a decisive role in tissue repair, thus affecting the final result of tissue repair. Biomimetic biomedical scaffolds have been widely used in tendon-bone interface, bone cartilage interface, nerve, vascular regeneration, and other fields, providing a promising new idea in clinical practice. [ABSTRACT FROM AUTHOR]

BACKGROUND: Scaffold materials serve as platforms that provide space and structure, playing a crucial role in the regeneration of cartilage tissue. Scholars from around the world are exploring different approaches to fabricate more ideal scaffold materials. OBJECTIVE: To review the design principles and preparation methods of cartilage scaffolds, and to further explore the advantages and limitations of various preparation methods. METHODS: Literature searches were conducted on the databases of CNKI, WanFang Data, PubMed, and FMRS from 1998 to 2023. The search terms were “cartilage repair, cartilage tissue engineering, cartilage scaffold materials, preparation” in Chinese and English. A total of 57 articles were ultimately reviewed. RESULTS AND CONCLUSION: (1) The articular cartilage has a unique structure and limited self-repair capacity after injury. Even if self-repair occurs, the newly formed cartilage is typically fibrocartilage, which is far inferior to normal articular cartilage in terms of structure and mechanical properties. It is difficult to maintain normal function and often leads to degenerative changes. Currently, the design and fabrication of scaffold materials for cartilage repair need to consider the following aspects: biocompatibility and biodegradability, suitable pore structure and porosity, appropriate mechanical properties, and bioactivity. (2) Research on the preparation of cartilage scaffolds has made significant progress, continuously introducing new preparation methods and optimization strategies. These methods have their advantages and disadvantages, providing more possibilities for customized preparation and functional design of cartilage scaffolds according to specific requirements. [ABSTRACT FROM AUTHOR]

BACKGROUND: With the increasing number of tendon transplantation surgeries for tendon injuries, the demand for tendon tissue engineering scaffolds is increasing. Research has found that good pore size and porosity of implants contribute to tissue healing. OBJECTIVE: To review the types of materials currently published for tendon tissue engineering scaffolds and investigate the correlation between various tendon tissue engineering scaffold materials and pores. METHODS: Articles were retrieved on PubMed, Embase, and Web of Science databases, using keywords “tendon” or “ligament” and “tissue scaffold” as well as “porosity” or “permeability”. A total of 84 articles meeting the criteria were included to summarize, discuss and anticipate future development directions. RESULTS AND CONCLUSION: The materials used in the research of tendon tissue engineering are mainly divided into two categories: natural tendon scaffold materials and artificial synthetic tendon scaffold materials. Natural scaffold materials include autologous tendons, allogeneic tendons, and xenogeneic tendons. Autogenous tendons and allogeneic tendons have been used in clinical practice for many years. During the preparation of allogeneic tendons and animal experiments, it was found that the process of acellular disinfection resulted in an increase in the pore size and porosity of both types of tendons, but the specific reasons and mechanisms have not been further studied. There are many types of artificial tendon scaffold materials currently being studied, among which artificial ligament products such as Leeds Keio and LARS (Ligament Advanced Reinforcement System) are still in use in some countries. Other materials have not been promoted in clinical practice due to immature technology and other issues. The pores and porosity of artificial tendon scaffold materials also show different trends due to their different materials and preparation techniques. [ABSTRACT FROM AUTHOR]

BACKGROUND: Due to the sudden release and the rapid removal by proteases, platelet-rich plasma hydrogel leads to shorter residence times of growth factors at the wound site. In recent years, researchers have focused on the use of hydrogels to encapsulate platelet-rich plasma in order to improve the deficiency of platelet-rich plasma hydrogels. OBJECTIVE: To prepare self-assembled polypeptide-platelet-rich plasma hydrogel and to explore its effects on the release of bioactive factors of platelet-rich plasma. METHODS: The self-assembled polypeptide was synthesized by the solid-phase synthesis method, and the solution was prepared by D-PBS. Hydrogels were prepared by mixing different volumes of polypeptide solutions with platelet-rich plasma and calcium chloride/thrombin solutions, so that the final mass fraction of polypeptides in the system was 0.1%, 0.3%, and 0.5%, respectively. The hydrogel state was observed, and the release of growth factors in platelet-rich plasma was detected in vitro. The polypeptide self-assembly was stimulated by mixing 1% polypeptide solution with 1% human serum albumin solution, so that the final mass fraction of the polypeptide was 0.1%, 0.3%, and 0.5%, respectively. The flow state of the liquid was observed, and the rheological mechanical properties of the self-assembled polypeptide were tested. The microstructure of polypeptide (mass fraction of 0.1% and 0.001%) -human serum albumin solution was observed by scanning electron microscope and transmission electron microscope. RESULTS AND CONCLUSION: (1) Hydrogels could be formed between different volumes of polypeptide solution and platelet-rich plasma. Compared with platelet-rich plasma hydrogels, 0.1% and 0.3% polypeptide-platelet-rich plasma hydrogels could alleviate the sudden release of epidermal growth factor and vascular endothelial growth factor, and extend the release time to 48 hours. (2) After the addition of human serum albumin, the 0.1% polypeptide group still exhibited a flowing liquid, the 0.3% polypeptide group was semi-liquid, and the 0.5% polypeptide group stimulated self-assembly to form hydrogel. It was determined that human serum albumin in platelet-rich plasma could stimulate the self-assembly of polypeptides. With the increase of the mass fraction of the polypeptide, the higher the storage modulus of the self-assembled polypeptide, the easier it was to form glue. (3) Transmission electron microscopy exhibited that the polypeptide nanofibers were short and disordered before the addition of human serum albumin. After the addition of human serum albumin, the polypeptide nanofibers became significantly longer and cross-linked into bundles, forming a dense fiber network structure. Under a scanning electron microscope, the polypeptides displayed a disordered lamellar structure before adding human serum albumin. After the addition of human serum albumin, the polypeptides self-assembled into cross-linked and densely arranged porous structures. (4) In conclusion, the novel polypeptide can self-assemble triggered by platelet-rich plasma and the self-assembly effect can be accurately adjusted according to the ratio of human serum albumin to polypeptide. This polypeptide has a sustained release effect on the growth factors of platelet-rich plasma, which can be used as a new biomaterial for tissue repair. [ABSTRACT FROM AUTHOR]

BACKGROUND: Gold nanoparticles are of great significance in the development of multifunctional transdermal drug delivery systems. Smaller gold nanoparticles can penetrate the dermis through the intercellular pathway, but are limited to their easy agglomeration and colloidal morphology, which makes it difficult to exert effects on low delivery efficiency. OBJECTIVE: To develop an ultrasound-optimized hydrogel delivery system by combining phase change nanodroplets with bio-adhesive hydrogel for percutaneous delivery of gold nanoparticles. METHODS: The ultrasound-responsive nanodroplets loaded with gold nanoparticles were prepared by the emulsion solvent evaporation method and loaded into the polydopamine-modified methylacryloyl gelatin hydrogel to prepare a composite hydrogel scaffold. The structure and chemical composition of the ultrasound-responsive nanogold carrier were characterized. The microstructure, porosity, permeability, rheology, in vitro hemostasis, and antibacterial properties of the composite hydrogel were characterized. The cell compatibility of the hydrogel scaffold was evaluated by live/dead staining, and the optimization effects of low-intensity pulsed ultrasound on the permeability, porosity, and mechanical properties of hydrogel were evaluated. RESULTS AND CONCLUSION: (1) Transmission electron microscopy and ultraviolet-visible spectroscopy proved the successful construction of nanogold carriers. The particle size and potential results demonstrated that the synthesized nanoscaled ultrasonic responsive carrier had good stability. (2) Live/dead cell staining proved that the prepared composite hydrogel scaffold had certain biocompatibility. (3) Scanning electron microscopy exhibited that the prepared composite hydrogel scaffold had a porous network structure, and numerous pores of about 2 μm appeared inside the macropores after the addition of nanodroplets and ultrasonic irradiation. The permeability experiment displayed that low-intensity pulsed ultrasound could optimize the porosity and permeability of hydrogel materials. The hemostatic performance of the composite hydrogel scaffold was better than that of the hemostatic sponge and polydopamine@ methylacrylylated gelatin hydrogel scaffold. Under the irradiation of low-intensity pulsed ultrasound, the composite hydrogel scaffolds had good antioxidant effects and antibacterial properties. (4) Thermal imaging results manifested that gold nanoparticles were encapsulated in ultrasound-responsive nanobubbles, and more uniform dispersion could be obtained under ultrasonic excitation. (5) The results of the mechanical property test demonstrated that the storage modulus of the hydrogel increased before and after loading gold nanoparticles-nanodroplets, which showed stronger mechanical properties. The elongation at break was 122%, and the ductility was better than that without gold nanoparticles-nanodroplets (P < 0.05). (6) These findings indicate that the composite hydrogel scaffold has good biocompatibility, antibacterial property, oxidation resistance, and hemostatic effect. [ABSTRACT FROM AUTHOR]

BACKGROUND: Tendinopathy is a musculoskeletal disorder characterized by pain and decreased mobility, with pathological changes of disturbed collagen and hyperplasia of the vasculature. Tendinopathy tends to occur in athletes, physical workers, and the elderly. One of the mechanisms of tendinopathy is the “failed healing response”, and part of what causes the failed healing response is the erroneous differentiation of tendon stem/progenitor cells. OBJECTIVE: By reviewing the relevant literature, we introduce the characteristics of tendon stem/progenitor cells, summarize the factors that affect the differentiation of tendon stem/progenitor cells to tendon cells and those that lead to mis-differentiation of tendon stem/progenitor cells (differentiation to adipocytes, osteocytes and chondrocytes), and also describe the limitations of tendon stem/progenitor cells in clinical applications. METHODS: PubMed and Web of Science databases were searched for the terms “tendon stem/progenitor cells, tendinopathy, tendon injury, differentiation”. The relevant literature was screened by reading and 109 articles were included for the analysis of the results. RESULTS AND CONCLUSION: (1) Tendon stem/progenitor cells are a type of stem cells that can spontaneously differentiate into tendons and have the ability to self-renew, clone, and multi-differentiate. Various external conditions acting on tendon stem/progenitor cells can lead them to differentiate in diverse directions. The specific factors that regulate the fate of tendon stem/progenitor cells are not known with certainty. When stem cell renewal and differentiation in tendons becomes abnormal, it can lead to failure of tendon healing and consequently to tendinopathy. (2) Aging, changes in extracellular matrix composition, excessive mechanical stimulation, prostaglandin E2 and interleukin-6 as well as interleukin-10 and some systemic diseases may be important in regulating the mis-differentiation of tendon stem/progenitor cells. (3) Possible favorable factors that promote the differentiation of tendon stem/progenitor cells to tenocytes are: some growth factors and cytokines, moderate mechanical stimulation and topography of the extracellular matrix, low oxygen tension, drugs, and several transcriptional genes and proteins. (4) The most desirable therapeutic tools are the regulation of endogenous tendon stem/progenitor cells or the stimulation of endogenous tendon stem/progenitor cell proliferation and differentiation by exogenous tendon stem/progenitor cells. (5) Understanding the factors that regulate mis-differentiation of tendon stem/progenitor cells may provide insight into the pathogenesis of tendinopathy and identify therapeutic targets. Elaborating on the induction of tendon stem/progenitor cell differentiation into tendons could facilitate their use in tissue engineering. [ABSTRACT FROM AUTHOR]

BACKGROUND: Vascularization is essential for wound healing and functional recovery during soft tissue repair. Adipose tissue is believed to be the body’s largest source of stem cells, and a number of different fat complexes have been developed for research and treatment. Its ability to promote angiogenesis and soft tissue repair has been extensively studied. OBJECTIVE: To review the progress of vascularization in soft tissue repair, and to summarize the preparation methods of adipose tissue and its derivative and their applications in vascularization and soft tissue repair. It is proven that adipose tissue and its derivative have excellent research value and clinical application prospects in vascular and soft tissue engineering. METHODS: PubMed, Web of Science and CNKI databases were used to search the related articles published from January 2010 to February 2023. The search terms were “soft tissue repair, wound healing, vascularization, angiogenesis, adipose tissue, stromal vascular fraction, adipose tissue-derived microvascular fragment, nanofat, adipose extracellular matrix/stromal vascular fraction gel” in Chinese and English. A small number of old classic literature was also included. An initial screening was performed by reading the titles and abstracts to exclude literature that was not relevant to the topic of the article, and 69 papers were finally included for the analysis of the result. RESULTS AND CONCLUSION: (1) Wound healing is an important physiological process, which mainly occurs when tissue is damaged, such as injury, surgery, burn, tumor, infection and vascular disease caused by tissue damage and defects. (2) Adequate vascularization of the wound site is essential for tissue repair, reconstruction of local homeostasis and functional recovery. (3) Adipose tissue is believed to be the body’s largest pool of stem cells and a number of different fat components have been used for research and treatment. (4) Due to its inherent composition and preparation advantages, adipose tissue will continue to play an important role in tissue engineering research and therapy. [ABSTRACT FROM AUTHOR]

Chitosan, a natural polymer, is widely used in various fields of tissue engineering due to its excellent biocompatibility, safe degradation behavior, and low immunogenicity. Research indicates that both chitosan and its degradation products exhibit potential interactions with cells related to nerve regeneration and the neural microenvironment. This interaction contributes to enhancing axonal regeneration while minimizing neuroma formation. Consequently, researchers have focused on designing diverse scaffold forms using chitosan as the fundamental material for addressing different types of peripheral nerve injuries. These advancements lay a foundation for the prospective application of chitosan scaffolds in peripheral nerve repair. In neural tissue engineering, chitosan is utilized to construct different forms of neural tissue engineering scaffolds, mimicking the natural structure of peripheral nerves and guiding the regeneration of damaged nerves, which has become the main research direction in peripheral nerve repair. This review delves into the multifaceted applications and burgeoning advancements surrounding various chitosan scaffolds, ranging from hydrogels, films, microspheres, to conduits-in the context of peripheral nerve injury rehabilitation. Moreover, it meticulously scrutinizes extant challenges and envisages future research trajectories, thereby offering valuable insights to propel the exploration and eventual clinical integration of chitosan-based neural tissue engineering scaffolds. [ABSTRACT FROM AUTHOR]

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Objective: To engineer a BCMA mutant resistant to γ-secretase cleavage in order to stabilize wild-type BCMA expression after γ-secretase cleavage and to generate target cells for measuring BCMA CAR-T cell cytotoxicity. Methods: Our study aimed to engineer a mutant BCMA protein (BCMA-CD8α TM) that could resist γ-secretase cleavage by replacing the transmembrane domain of the wild-type BCMA protein with the human CD8α sequence. Four different types of cells in which this mutant gene was expressed excessively were engineered, including U266 (U266BCMA Mut), K562 (K562BCMA Mut), SKOV3 (SKOV3BCMA Mut), and CHO (CHOBCMA Mut) cells. BCMA CAR Jurkat cells, loaded with the NFAT-EGFP reporter gene (BCMA-CAR-Jurkat-Reporter), were engineered and cocultured with U266BCMA Mut cells. The expression level of EGFP was detected by FCM in order to indicate the activation level of NFAT. The cytotoxicity of BCMA CAR-T cells against Luciferase-labeled K562BCMA Mut cells was detected by the luciferase assay. Additionally, real-time cell analysis (RTCA) technique was employed to detect the cytotoxicity of BCMA CAR-T cells against SKOV3BCMA Mut and CHOBCMA Mut cells. Results: Application of γ-secretase inhibitor LY411575 to inhibit γ-secretase activity significantly enhanced the expression level of BCMA on the surface of wild-type U266 cells, and the average fluorescence intensity was increased by more than 10 times. However, the expression level of BCMA gradually decreased after removal of inhibitors (P<0.01). BCMA-CD8α TM mutant could resist the cleavage of γ-secretase and expressed stably on the surface of U266 cells (P>0.05). U266 cells and U266 cells overexpressing BCMA-CD8α TM were co-incubated with BCMA-CAR-Jurkat-Reporter cells, both of which could activate the Reporter system and enhance the expression of EGFP, but the effect was more significant in U266 cells overexpressing BCMA-CD8α TM (P<0.01). BCMA-CD8α TM mutants were successfully overexpressed in 3 BCMA-negative target cells, namely K562, SKOV3 and CHO cells, and the expression level of the mutant was only slightly increased under LY411575 treatment. Luciferase assay results showed that under different target-effect ratios BCMA CAR-T cells could all be specific and efficient in killing K562 cells overexpressing BCMA-CD8α TM. RTCA results showed that under different target ratios BCMA CAR-T cells could all effectively recognize and kill SKOV3 and CHO cells overexpressing BCMA-CD8α TM, but Mock-T cells with the same target ratio had no such effect. Conclusion: The BCMA-CD8α TM mutant engineered in this study can resist γ-secretase cleavage and exhibits stable surface expression on various target cells, thus offering various methods for evaluating the efficacy and specificity of BCMA CAR-T cell cytotoxicity in vitro. [ABSTRACT FROM AUTHOR]

BACKGROUND: Knee osteoarthritis is a degenerative disease caused by multiple factors. Its pathogenesis is complex and still unclear. Chinese medicine in the treatment of knee osteoarthritis is fruitful, and in-depth study of Chinese medicine in the treatment of knee osteoarthritis is of great significance. OBJECTIVE: To review the progress of Chinese medicine monomers and compounds in the treatment of knee osteoarthritis and to provide ideas and reference for the effective prevention and treatment of knee osteoarthritis. METHODS: CNKI, WanFang, VIP, PubMed, MEDLINE, Nature, and Cochrane databases were retrieved for relevant literature published from database inception to 2022. The keywords were “knee osteoarthritis, cartilage damage, traditional Chinese medicine, Chinese herbal compound, treatment” in Chinese and English. Duplicates and obsolete non-referenced literature were excluded, and a total of 62 standard papers were included for further review. RESULTS AND CONCLUSION: Some of the pathogeneses of knee osteoarthritis include immune inflammatory response, chondrocyte autophagy and apoptosis, vascular endothelial growth factor level and biomechanical imbalance. The mechanisms by which traditional Chinese medicine treats knee osteoarthritis mainly focus on regulating inflammatory factor levels, chondrocyte autophagy and apoptosis, and vascular endothelial growth factor level and improving cartilage performance, so as to delay the occurrence and development of knee osteoarthritis. [ABSTRACT FROM AUTHOR]

BACKGROUND: The repair of articular cartilage injury remains a difficult problem to be solved urgently in clinical practice. Utilizing synthetic or biological materials to promote cartilage regeneration has been a research hotspot. OBJECTIVE: To review the research progress of synthetic and biological materials in articular cartilage repair. METHODS: PubMed and CNKI databases were searched for articles about the progress of synthetic and biological materials utilized in articular cartilage repair. “Collagen, gelatin, silk, chitosan, alginate, PEG, PCL, PLA, cartilage tissue engineering, cartilage tissue engineering materials” were used as English and Chinese search terms, respectively. After preliminary screening based on the inclusion and exclusion criteria, 98 articles with high quality and relevance were retained for review. RESULTS AND CONCLUSION: Natural materials, including collagen, gelatin, silk, chitosan, and alginate, have good biocompatibility and degradability. Synthetic materials, containing polyethylene glycol, polycaprolactone, and polylactic acid, have good mechanical properties. Modification and composition of materials can overcome the inherent defects in materials and show better cartilage repair ability. Studies about multi-layer scaffolds based on hierarchical structure are rare, and it is more targeted at osteochondral injury repair rather than simple cartilage injury repair. At present, scaffold research is focused on the synthetic research and development stage, and the corresponding clinical trials are few, so it is necessary to pay attention to clinical transformation in the future. [ABSTRACT FROM AUTHOR]

BACKGROUND: With computer-aided design, melt electrowriting technology can precisely construct 3D tissue engineering scaffolds with specific morphology, which has attracted increasing attention in tissue engineering. OBJECTIVE: To elaborate on the progress of melt electrowriting technology in tissue engineering in recent years. METHODS: PubMed and CNKI were used to retrieve articles about applications of melt electrowriting technology in tissue engineering. The search time was from March 2008 to February 2023. The search terms were “melt electrowriting, melt electrospinning, electrospinning, tissue engineering, scaffold, regeneration” in English and “melt electrowriting, electrospinning, tissue engineering” in Chinese. A preliminary screening of articles was performed by reading the titles and abstracts. Finally, 69 articles were included for review. RESULTS AND CONCLUSION: (1) Melt electrowriting technology can achieve precise layer-by-layer deposition of fibers compared to traditional electrospinning technology, which better simulates the complex structure of natural tissues. Compared to other 3D printing technologies, smaller-diameter fibers can be prepared by melt electrowriting technology, resulting in highly ordered porous structures. (2) By combining with other scaffold preparation techniques or materials, such as fused deposition modeling, solution electrospinning technology, and hydrogel, melt electrowriting technology shows great potential in preparing complex tissue engineering scaffolds, which provides certain possibilities for achieving complex tissue regeneration. (3) The regeneration of complex tissues often involves blood vessels, nerves, and soft and hard tissues at the same time. The regeneration of blood vessels and nerves is of great significance to realize the physiological reconstruction of tissues. However, soft and hard tissues have certain difficulties to realize the coordinated regeneration of both due to their different biological and mechanical properties. Melt electrowriting technology has certain advantages in the field of bionic scaffolds due to its good biocompatibility, the ability to prepare multi-scale scaffolds and high porosity. [ABSTRACT FROM AUTHOR]

BACKGROUND: Recently, regenerative endodontic therapy is a promising alternative to the maturation of tissue engineering. Inflammatory microenvironment plays a key role in regulating pulp regeneration. OBJECTIVE: To focus on the change in the inflammatory pulp microenvironment, the balance between inflammation and regeneration, and the research advances in tissue-engineered regenerative endodontic therapy within the context of the inflammatory microenvironment to provide a reference for future investigations into regenerative endodontic therapy. METHODS: We conducted a literature search on PubMed and CNKI using search terms “pulp regeneration, inflammation, regenerative endodontic therapy, tissue engineering” in Chinese and English for articles published between 2013 and 2023. The review finally included 61 relevant articles. RESULTS AND CONCLUSION: (1) The changes in the microenvironment of pulpitis involve a complex interplay of cellular and molecular reactions, which, as inflammation progresses, ultimately the microenvironment hinders tissue repair more than facilitates it. (2) Inflammation can promote dental pulp regeneration through stem cell recruitment and activate the complement system, but it can also hinder the regenerative process through immunosuppression and fibrosis. (3) Tissue engineering’s three components (stem cells, growth factors, scaffold materials) collaborate to balance inflammation and regeneration, for example, by using interleukin-6 to regulate dental pulp stem cells and foster a regenerative environment. (4) Current research has been largely silent on infection and inflammation issues. The mechanisms underlying changes in the microenvironment of pulpitis are still not fully understood. One promising avenue for improving the clinical applicability of regenerative dental pulp therapy is to achieve precise regulation of the inflammatory-regeneration balance and create a regenerative microenvironment by synergistically leveraging the three elements of tissue engineering. However, this field of investigation still exhibits significant gaps in understanding, necessitating further exploration into innovative strategies for facilitating dental pulp regeneration under inflammation. As such, additional animal experimentation and randomized clinical trials are required to establish a robust foundation for the clinical practice of tissue engineeringbased regenerative dental pulp therapy. [ABSTRACT FROM AUTHOR]