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In recent years, people have had more expectations from the developed technology in medicine, especially in the field of orthopedics and traumatology. Tissue engineers are interested in techniques that benefit from patients' cells and biomaterials, instead of prostheses and implants. On the other hand, researchers have begun to use various medicinal plants for regeneration and anti-cancer studies. In the present study, we aimed to produce cartilage and bone inductive scaffolds for osteochondral tissue engineering applications with the addition of hawthorn or elderberry extracts. Firstly, wet electro-spun poly (3-hydroxybutyric acid-co-3-hydroxyvaleric acid) fibers were integrated with a loofah mat. Then, they were impregnated into chitosan solution with/without hawthorn or elderberry extract. Composite hydrogel scaffolds were obtained by cross-linking with 0.3% (w/v) genipin. Fabricated scaffolds had more than 90% porosity and showed swelling capacity in the range of 1500–2200%. Based on the in vitro biocompatibility analyses using mesenchymal stem cells (MSCs), all the fabricated scaffolds were found to be biocompatible by WST-1, ALP activity, and GAG content analysis. Also, histological/immunohistochemical analyses showed that hawthorn and elderberry extract addition increased MSCs proliferation and collagen type I and II positivity. Consequently, all the scaffolds showed promising features for osteochondral tissue engineering applications. [ABSTRACT FROM AUTHOR]

Decellularization of plant tissues is an emerging route to fabricate scaffolds for tissue engineering and regenerative medicine. Although significant progress has been made in the field of plant tissue decellularization, functionalization of plant scaffolds is still an emerging field, and loading them with L-ascorbic acid to promote skin regeneration has not yet been reported. L-ascorbic acid is an antioxidant that plays a key role in collagen synthesis as a cofactor of lysyl hydroxylase and prolyl hydroxylase. It has been shown to have significant importance in physiological wound healing by stimulating fibroblasts to produce collagen at both the molecular and the genetic levels. In this work, we aimed to fabricate an ascorbic acid-releasing bioactive scaffold by introducing a stable form of ascorbic acid, L-ascorbic acid 2-phosphate (AA2P), into decellularized baby spinach leaves and investigated its biological activity in vitro. Our results demonstrated that AA2P could be easily introduced into decellularized baby spinach leaf scaffolds and subsequently released within the effective dose range. AA2P-releasing baby spinach leaves were found to increase metabolic activity and enhance collagen synthesis in L929 fibroblasts after 21 days. In conclusion, this study demonstrated the fabrication of a novel functionalized skin tissue engineering scaffold and made a significant contribution to the fields of plant decellularization and skin tissue engineering. [ABSTRACT FROM AUTHOR]

Advanced therapeutic dressings are the current research interest that achieves rapid and complete wound healing. The healing of skin wounds demonstrates a remarkable cellular function process that is distinct in nature and involves the interaction of various cells, growth factors, and cytokines. In this study, nanofibrous scaffolds were prepared using poly(ε-caprolactone) and polylactic acid as mat scaffolds. Also, copper nanoparticles (CuNPs) and curcumin were added to fabricate a hybrid nanocomposite scaffold using the electrospinning technique. The fabricated scaffolds were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), tensile analysis, porosity, and water vapor transmission rate. SEM analysis proved the nanostructured fibers have suitable porosity without any beads. The presence of CuNPs in the PCL-Cu nanofibrous mat was confirmed by TEM analysis. The tensile test confirmed an increase and decrease in the elongation ratio by CuNPs and curcumin addition, respectively. The biocompatibility and cell attachment to the nanofibers were proved by MTT and DAPI staining which proved a significantly positive effect of curcumin in the cell growth. The scaffold can hinder both the gram-negative and gram-positive bacteria through direct contact with them. This research study showed that the addition of CuNPs and curcumin in the hybrid nanocomposite scaffold compensates for each other's shortcomings and has the potential to be used in wound healing applications. [ABSTRACT FROM AUTHOR]

Tissue engineering applications in bone defect treatment have shown promising outcomes over the past decade. In this context, taking advantage of bioactive scaffolds mimicking the intrinsic composition of bone has resulted in remarkable effects on bone regeneration. In this study, Zirconium-based metal-organic framework, known as MOF 801, was synthesized and incorporated into the gelatin matrix as an osteoconductive agent to fabricate a nanocomposite bone scaffold by freeze-drying method. Physical and chemical characteristics of MOF 801 and nanocomposite scaffolds were analyzed using FE-SEM, EDS, XRD, ICP and FTIR. Besides, the biological activity of the prepared scaffolds was evaluated by MTT, alizarin red staining, crystal violet staining, and ALP assays. Inclusion of MOF 801 NPs into the scaffolds resulted in enhancement of their compressive strength up to 15 ± 0.05 MPa. The nanocomposite samples containing MOF 801 NPs also exhibited favorable bioactive feature that was confirmed by their apatite-forming ability on their surfaces upon immersion in SBF solution. The Zr ion and fumarate release studies illustrated sustained release profiles from the gelatin matrix, leading to both antioxidant and anti-inflammatory properties. MTT assay results affirmed biocompatibility of scaffolds containing up to 5 % w/w MOF 801, besides the crystal violet assay exhibited proper cell confluency and adhesion. Eventually, Alizarin red and ALP activity assays revealed that an increment of MOF 801 could induce calcium mineralization and Alkaline Phosphatase enzyme production in MG-63 cells confirming the potential of prepared scaffolds for related bone tissue engineering applications. [ABSTRACT FROM AUTHOR]

Skin injuries are common problems and large skin defects or infected skin needs extra attention that make the researchers find new solutions. Herein, a novel biocompatible, biodegradable antibacterial scaffold containing gelatin, TiO2, polycaprolactone, and silk fibroin loaded with different ratios of curcumin (0.5, 1, and 1.5% wt.) was fabricated with electrospinning technique and was tested with various in vitro tests. The cellular investigations (cell adhesion, cell viability, and in vitro migration test) and antibacterial assay revealed the higher efficiency of the scaffold with 1% wt. curcumin and further investigation were performed on this scaffold. The morphological observation confirmed the nanofibrous structure of the scaffold, with 0.10 ± 0.015 μm average fiber diameter. This scaffold showed hydrophilic nature with high swelling ratio absorption and 76.45 ± 5.19% degradation ratio after 2 weeks. Also, it could provide adequate mechanical properties for skin regeneration. The drug-releasing investigation revealed Cur's controlled release over 48 h. Therefore, this biocompatible and antibacterial scaffold showed high potential for treating skin injuries and is suggested for future in vivo studies. [ABSTRACT FROM AUTHOR]

Hydrogel skin grafts provide a moist environment and act as a regenerative template to the newly formed tissue. In this study, we developed 3D-bio-printed hydrogels using methacrylated pectin and methacrylated gelatin together with an antibacterial agent (curcumin), a bioactive agent (Vitamin-C) and fibroblast cells. Curcumin release was almost 10 times higher at pH 7.4 than pH 5.0, and it demonstrated antimicrobial affinity against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. The developed 3D-bio-printed hydrogels containing cells and bioactive agents demonstrated high cell viability, cell proliferation, and collagen production, and are promising skin graft candidates for the treatment of full-thickness problematic wounds. [ABSTRACT FROM AUTHOR]

Background: In bone tissue engineering segment, numerous approaches have been investigated to address critically sized bone defects via 3D scaffolds, as the amount of autologous bone grafts are limited, accompanied with complications on harvesting. Moreover, the use of bone-marrow-derived stem cells is also a limiting factor owing to the invasive procedures involved and the low yield of stem cells. Hence, research is ongoing on the search for an ideal bone graft system promoting bone growth and regeneration. Purpose of the Study: This study aims to develop a unique platform for tissue development via stem cell differentiation towards an osteogenic phenotype providing optimum biological cues for cell adhesion, differentiation and proliferation using biomimetic gelatin-based scaffolds. The use of adipose-derived mesenchymal stem cells in this study also offers an ideal approach for the development of an autologous bone graft. Methods: A gelatin-vinyl acetate-based 3D scaffold system incorporating Bioglass was developed and the osteogenic differentiation of adipose-derived mesenchymal stem cells (ADMSCs) on the highly porous freeze-dried gelatin-vinyl acetate/ Bioglass scaffold (GB) system was analyzed. The physicochemical properties, cell proliferation and viability were investigated by seeding rat adipose tissue-derived mesenchymal stem cells (ADSCs) onto the scaffolds. The osteogenic differentiation potential of the ADMSC seeded GeVAc/bioglass system was assessed using calcium deposition assay and bone-related protein and genes and comparing with the 3D Gelatin vinyl acetate coppolymer (GeVAc) constructs. Results and Conclusion: According to the findings, the 3D porous GeVAc/bioglass scaffold can be considered as a promising matrix for bone tissue regeneration and the 3D architecture supports the differentiation of the ADMSCs into osteoblast cells and enhances the production of mineralized bone matrix. [ABSTRACT FROM AUTHOR]

Electrospun nanofiber scaffolds mimic the structure of the natural extracellular matrix, making them promising for application in tissue engineering. Based on this, the biopolymers poly(ε-caprolactone) (PCL) and gelatin, with good mechanical and biological properties, respectively, were electrospun with acetic acid as the only solvent, without the crosslinking process in order to reduce the cytotoxic effects of commonly used solvents. This study evaluated the influence of scaffold thicknesses on the physicochemical properties. Scaffolds with 4 different thicknesses were produced by increasing the electrospinning time (A = 1 h, B = 1.5 h, C = 2 h and D = 3 h). Thicker scaffolds (B, C and D, 0.142 ± 0.029 to 0.306 ± 0.053 nm) were manipulated easily, presented higher mechanical strength (from 156.21 to 178.53%) and smaller diameter fibers (approximately 300.0 nm). On the other hand, the longer the processing time, the less uniform the fibers and more melting regions between fibers, which may hinder the use of the scaffold and should be considered. Only the thickest scaffold (D) showed higher wettability (contact angle 31.1° ± 3°). Intermediate thickness scaffolds showed less beads and fiber irregularities. Cell adhesion was good due to gelatin, though cell proliferation remained constant for the thicker scaffold indicating that longer processing time may not be advantageous for cell application. Results showed that intermediate thickness scaffolds of PCL/gelatin (0.142 ± 0.029 to 0.195 ± 0.034 nm) assure good physicochemical properties to be applied for different cell types. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) structures are actually the state-of-the-art technique to create porous scaffolds for tissue engineering. Since regeneration in cartilage tissue is limited due to intrinsic cellular properties this study aims to develop and characterize three-dimensional porous scaffolds of poly (L-co-D, L lactide-co-trimethylene carbonate), PLDLA-TMC, obtained by 3D fiber deposition technique. The PLDLA-TMC terpolymer scaffolds (70:30), were obtained and characterized by scanning electron microscopy, gel permeation chromatography, differential scanning calorimetry, thermal gravimetric analysis, compression mechanical testing and study on in vitro degradation, which showed its amorphous characteristics, cylindrical geometry, and interconnected pores. The in vitro degradation study showed significant loss of mechanical properties compatible with a decrease in molar mass, accompanied by changes in morphology. The histocompatibility association of mesenchymal stem cells from rabbit's bone marrow, and PLDLA-TMC scaffolds, were evaluated in the meniscus regeneration, proving the potential of cell culture at in vivo tissue regeneration. Nine New Zealand rabbits underwent total medial meniscectomy, yielding three treatments: implantation of the seeded PLDLA-TMC scaffold, implantation of the unseeded PLDLA-TMC and negative control (defect without any implant). After 24 weeks, the results revealed the presence of fibrocartilage in the animals treated with polymer. However, the regeneration obtained with the seeded PLDLA-TMC scaffolds with mesenchymal stem cells had become intimal to mature fibrocartilaginous tissue of normal meniscus both macroscopically and histologically. This study demonstrated the effectiveness of the PLDLA-TMC scaffold in meniscus regeneration and the potential of mesenchymal stem cells in tissue engineering, without the use of growth factors. It is concluded that bioresorbable polymers represent a promising alternative for tissue regeneration. [ABSTRACT FROM AUTHOR]

[Display omitted] Orderly hierarchical structure with balanced mechanical, chemical, and electrical properties is the basis of the natural bone microenvironment. Inspired by nature, we developed a piezocatalytically-induced controlled mineralization strategy using piezoelectric polymer poly-L-lactic acid (PLLA) fibers with ordered micro-nano structures to prepare biomimetic tissue engineering scaffolds with a bone-like microenvironment (pcm-PLLA), in which PLLA-mediated piezoelectric catalysis promoted the in-situ polymerization of dopamine and subsequently regulated the controllable growth of hydroxyapatite crystals on the fiber surface. PLLA fibers, as analogs of mineralized collagen fibers, were arranged in an oriented manner, and ultimately formed a bone-like interconnected pore structure; in addition, they also provided bone-like piezoelectric properties. The uniformly sized HA nanocrystals formed by controlled mineralization provided a bone-like mechanical strength and chemical environment. The pcm-PLLA scaffold could rapidly recruit endogenous stem cells, and promote their osteogenic differentiation by activating cell membrane calcium channels and PI3K signaling pathways through ultrasound-responsive piezoelectric signals. In addition, the scaffold also provided a suitable microenvironment to promote macrophage M2 polarization and angiogenesis, thereby enhancing bone regeneration in skull defects of rats. The proposed piezocatalytically-induced controllable mineralization strategy provides a new idea for the development of tissue engineering scaffolds that can be implemented for multimodal physical stimulation therapy. [ABSTRACT FROM AUTHOR]

Bone defect repair, particularly in the alveolar region, remains a significant hurdle in periodontics. In recent years, the spotlight in regenerative medicine has fallen on 3D-printed bone scaffolds, especially those constructed of polylactic acid (PLA) infused with hydroxyapatite. This research introduced a novel approach by developing a 3D-printed PLA scaffold enriched with hydroxyapatite derived from fish skin waste (FSHA). Mechanical compression tests revealed that the 3D-printed PLA-FSHA scaffolds had a compressive strength (13.4 ± 5.53 MPa) in the same ballpark as their reference PLA counterparts (20.3 ± 1.08 MPa). Scanning electron micrographs highlighted an average pore size in the scaffold (572 ± 33 μm) conducive to angiogenesis and facilitating cell migration and proliferation. In vitro, cytotoxicity was ascertained using the MTT assay on L929 fibroblast cells. Further in vitro cytocompatibility assessments through actin-DAPI staining and measurements of bone regeneration markers - alkaline phosphatase, osteocalcin and osteopontin-demonstrated that the PLA-FSHA scaffolds not only were biocompatible but also showcased performance on par with the commercial graft, osseograft. This lays the foundation for future in vivo evaluations of bone regenerative capabilities. [ABSTRACT FROM AUTHOR]

The cancer vaccine is one of the potent cancer immunotherapies based on provoking antigen‐specific adaptive immune responses in patients. Activating host antigen‐presenting cells by delivering antigens and adjuvants is one of the most important requirements to enhance cancer vaccine efficacy. This study proposes an effective cancer vaccine platform based on injectable mesocellular foam (MCF) silica microparticles with a dual role capable of in situ recruitment of host dendritic cells (DCs) and intracellular delivery of antigens to the recruited DCs. Subcutaneously administrated MCF microparticles loaded with chemoattractant to DCs (GM‐CSF), antigenic protein (OVA), and TLR9 agonist (CpG‐ODN) lead to robust DC maturation and high antigen‐specific T cell responses. The cell recruitment, DC activation, and T cell responses of MCF‐based cancer vaccine are significantly higher than injectable mesoporous silica scaffold, of which role is mostly limited to the cell recruiting scaffold. These features of MCF lead to effective inhibition of tumor growth in prophylactic vaccine setting and lung metastatic cancer model, representing MCF enabling cell‐recruiting scaffold formation and intracellular delivery of antigen can be a promising material platform for an enhanced cancer vaccine. [ABSTRACT FROM AUTHOR]

Harnessing endogenous stem/progenitor cells to enhance extracellular matrix (ECM) deposition in the nucleus pulposus (NP) is considered as a potential treatment for intervertebral disc degeneration (IVDD), but is limited by the lack of suitable scaffolds for cell infiltration and growth, as well as the tailored release of bioactive factors. Herein, an injectable cell‐free microgel assembly (MA‐TNS) with interconnected microporous structure is developed to recruit stem/progenitor cells and induce the differentiation of the recruited cells by releasing stromal cell‐derived factor‐1α (SDF‐1α) and transforming growth factor‐β1 (TGF‐β1) sequentially. TGF‐β1 is initially loaded by the chondroitin sulfate/gelatin nanoparticles. Together with SDF‐1α, these nanoparticles are co‐encapsulated into the photo‐cross‐linked microgels, which are then assembled into a microporous scaffold via dynamic boronate ester bonds. An initial rapid release of SDF‐1α followed by a sustained release of TGF‐β1 lasting over 28 days is achieved. MA‐TNS significantly promotes the recruitment, infiltration, and chondrocyte‐like differentiation of marrow mesenchymal stem cells in vitro. Furthermore, in vivo experiments on rats and cynomolgus monkeys prove that MA‐TNS can inhibit IVDD and recover ECM deposition markedly, thereby enabling long‐term NP reconstruction. The resulting efficacy in rats and nonhuman primates supports that MA‐TNS is a promising scaffold for intervertebral disc repair and regeneration. [ABSTRACT FROM AUTHOR]

Triple‐negative breast cancer (TNBC), a disease with a poor prognosis and high mortality, is difficult to targeted therapy, due to the metastatic nature of TNBC cells and their lack of estrogen, progesterone, and Her‐2/Neu receptor targets. Here, a novel pretargeting strategy involving self‐assembled peptides and a bioorthogonal reaction are described. This process generates nanofibers on TNBC cell surface that prevent them migration and invasion and deliver untargeted anticancer drugs (e.g., doxorubicin) that synergistically eliminates TNBC cells. The self‐assembled peptide contains four modules: i) an aromatic group‐rich tetraphenylethylene (TPE) unit for promoting self‐assembly and nanofiber formation, ii) a GFFY peptide motif that supports self‐assembly of nanofibers into peptide scaffolds, iii) a targeting RGD motif that binding with the abundant integrin molecules present on TNBC cell surface, and iv) an azide group acting as the bioorthogonal reaction site that reacts with drugs or probes containing the dibenzocyclooctyne (DBCO) group. Results of in vitro and in vivo experiments indicate that the self‐assembled peptide inhibits tumor invasion and metastasis, while also pretargeting and killing TNBC cells with superior effectiveness and lower toxicity to that of current chemotherapies. In conclusion, this novel bioorthogonal pretargeting strategy holds promise as an effective anticancer therapeutic approach. [ABSTRACT FROM AUTHOR]

3D printing technology is a powerful tool in scaffold engineering for biomedical applications, especially in anticancer activities and drug delivery. The present study developed a 3D-printed gelatin–alginate scaffold incorporating letrozole-loaded niosomes (Let/Nio@Gel-AL-SC) as a more effective drug delivery system. The findings showed that the fabricated niosomes appeared spherical. 3D-printed scaffolds exhibited biodegradability and sustained drug-release properties. The drug release from the scaffold was less prominent under acidic conditions than physiological ones. Cytotoxicity analysis showed that the engineered Let/Nio@Gel-AL-SC scaffold exhibited significant cytotoxicity against MCF-7 cancer cells. Gene expression analysis demonstrated a significant decrease in the expression of BCL2, CCND1, MMP2, and CDK4 genes and a notable increase in the expression of BAX and P53 genes, as well as the activity of Caspase 3/7 enzyme following treatment with Let/Nio@Gel-AL-SC. In addition, flow cytometry analysis revealed that Let/Nio@Gel-AL-SC significantly reduced necrosis and dramatically increased apoptosis. Also, the Let/Nio@Gel-AL-SC formulation exhibited a significantly greater increase in ROS values. The incorporation of letrozole-loaded niosomes into 3D printing gelatin/alginate scaffold has enhanced the efficacy of anticancer therapy. This is demonstrated by the sustained release of drugs, which indicates a promising potential for effective anticancer activity. Consequently, this combination holds promise as a potential future cancer therapy strategy. [ABSTRACT FROM AUTHOR]

In the context of tissue engineering, biofabrication techniques are employed to process cells in hydrogel-based matrices, known as bioinks, into complex 3D structures. The aim is the production of functional tissue models or even entire organs. The regenerative production of biological tissues adheres to a multitude of criteria that ultimately determine the maturation of a functional tissue. These criteria are of biological nature, such as the biomimetic spatial positioning of different cell types within a physiologically and mechanically suitable matrix, which enables tissue maturation. Furthermore, the processing, a combination of technical procedures and biological materials, has proven highly challenging since cells are sensitive to stress, for example from shear and tensile forces, which may affect their vitality. On the other hand, high resolutions are pursued to create optimal conditions for subsequent tissue maturation. From an analytical perspective, it is prudent to first investigate the printing behavior of bioinks before undertaking complex biological tests. According to our findings, conventional shear rheological tests are insufficient to fully characterize the printing behavior of a bioink. For this reason, we have developed optical methods that, complementarily to the already developed tests, allow for quantification of printing quality and further viscoelastic modeling of bioinks. [ABSTRACT FROM AUTHOR]

Chemobrionic systems have attracted great attention in material science for development of novel biomimetic materials. This study aims to design a new bioactive material by integrating biosilica into chemobrionic structure, which will be called biochemobrionic, and to comparatively investigate the use of both chemobrionic and biochemobrionic materials as bone scaffolds. Biosilica, isolated from Amphora sp. diatom, was integrated into chemobrionic structure, and a comprehensive set of analysis was conducted to evaluate their morphological, chemical, mechanical, thermal, and biodegradation properties. Then, the effects of both scaffolds on cell biocompatibility and osteogenic differentiation capacity were assessed. Cells attached to the scaffolds, spread out, and covered the entire surface, indicating the absence of cytotoxicity. Biochemobrionic scaffold exhibited a higher level of mineralization and bone formation than the chemobrionic structure due to the osteogenic activity of biosilica. These results present a comprehensive and pioneering understanding of the potential of (bio)chemobrionics for bone regeneration. [ABSTRACT FROM AUTHOR]

Advancing the integration of nonliving and living components relies heavily on functional hydrogel materials with biocompatibility and customizability. In this study, an enzyme‐assisted surface activation method is developed to produce reactive hydrogel microparticles (HMPs) comprising thiolated hyaluronic acid and hyperbranched poly(β‐hydrazide esters). Fluorescence labeling analysis reveals an over six‐fold increase in surface‐active functional group density on the hydrogels and three‐fold on HMPs after enzyme activation. This enhancement improves accessibility of active elements, facilitating post‐functionalization and optimizing their capacity to support initial cell adhesion and spreading as carriers for cell cultures. Additionally, by utilizing the exposed reactive double bonds on the HMP surfaces post‐enzymatic treatment, thiolated HMPs are produced through a thiol‐ene coupling reaction with thiolated polymers. These thiolated HMPs bond together spontaneously, resulting in the formation of annealed granular hydrogels with interconnected large‐pore networks and a tunable storage modulus (G’) from tens to hundreds of pascals, compatible with most soft tissues. Integrated with 3D bioprinting, this hydrogel ink generates prints that foster cell adhesion, migration, growth, and network formation. Moving forward, integrating various granular hydrogel scaffold systems with the enzyme‐assisted activation technique holds significant promise for enhancing performance and expanding applications in regenerative medicine and innovative living materials. [ABSTRACT FROM AUTHOR]

The ideal tissue engineering scaffold should facilitate rapid cell infiltration and provide an optimal immune microenvironment during interactions with the host. Electrospinning can produce two-dimensional (2D) membranes mimicking the extracellular matrix. However, their dense structure hinders cell penetration, and their thin form restricts scaffold utility. In this study, latticed hydrogels were three-dimensional (3D) printed onto electrospun membranes. This technique allowed for layer-by-layer assembly of the membranes into 3D scaffolds, which maintained their resilience impressively under both dry and wet conditions. We assessed the cellular and host responses of these 3D nanofiber scaffolds by comparing random membranes and mesh-like membranes with three different mesh sizes (250, 500, and 750 μm). It was found that scaffolds with a mesh size of 500 μm were superior for M2 macrophage phenotype polarization, vascularization, and matrix deposition. Furthermore, it was confirmed by subsequent experiments such as RNA sequencing that the mesh-like topology may promote polarization to the M2 phenotype by affecting the PI3K/AKT pathway. In conclusion, our work offers a novel method for transforming 2D nanofiber membranes into 3D scaffolds. This method boasts flexibility, allowing for the use of varied electrospun membranes and hydrogels in terms of structure and composition. It has vast potential in tissue repair and regeneration. [ABSTRACT FROM AUTHOR]

3D bioprinting techniques have enabled the fabrication of irregular large‐sized tissue engineering scaffolds. However, complicated customized designs increase the medical burden. Meanwhile, the integrated printing process hinders the cellular uniform distribution and local angiogenesis. A novel approach is introduced to the construction of sizable tissue engineering grafts by employing hydrogel 3D printing for modular bioadhesion assembly, and a poly (ethylene glycol) diacrylate (PEGDA)‐gelatin‐dopamine (PGD) hydrogel, photosensitive and adhesive, enabling fine microcage module fabrication via DLP 3D printing is developed. The PGD hydrogel printed micocages are flexible, allowing various shapes and cell/tissue fillings for repairing diverse irregular tissue defects. In vivo experiments demonstrate robust vascularization and superior graft survival in nude mice. This assembly strategy based on scalable 3D printed hydrogel microcage module could simplify the construction of tissue with large volume and complex components, offering promise for diverse large tissue defect repairs. [ABSTRACT FROM AUTHOR]

The extracellular matrix (ECM) serves as a scaffold for cells and plays an essential role in regulating numerous cellular processes, including cell migration and proliferation. Due to limitations in specimen preparation for conventional roomtemperature electron microscopy, we lack structural knowledge on how ECM components are secreted, remodeled, and interact with surrounding cells. We have developed a 3D-ECM platform compatible with sample thinning by cryo-focused ion beam milling, the lift-out extraction procedure, and cryo-electron tomography. Our workflow implements cell-derived matrices (CDMs) grown on EM grids, resulting in a versatile tool closely mimicking ECM environments. This allows us to visualize ECM for the first time in its hydrated, native context. Our data reveal an intricate network of extracellular fibers, their positioning relative to matrix-secreting cells, and previously unresolved structural entities. Our workflow and results add to the structural atlas of the ECM, providing novel insights into its secretion and assembly. [ABSTRACT FROM AUTHOR]

The porous structure of microgels significantly influences their properties and, thus, their suitability for various applications, in particular as building blocks for tissue scaffolds. Porosity is one of the crucial features for microgel–cell interactions and significantly increases the cells' accumulation and proliferation. Consequently, tailoring the porosity of microgels in an effortless way is important but still challenging, especially for nonspherical microgels. This work presents a straightforward procedure to fabricate complex‐shaped poly(N‐isopropyl acrylamide) (PNIPAM) microgels with tuned porous structures using the so‐called cononsolvency effect during microgel polymerization. Therefore, the classical solvent in the reaction solution is exchanged from water to water–methanol mixtures in a stop‐flow lithography process. For cylindrical microgels with a higher methanol content during fabrication, a greater degree of collapsing is observed, and their aspect ratio increases. Furthermore, the collapsing and swelling velocities change with the methanol content, indicating a modified porous structure, which is confirmed by electron microscopy micrographs. Furthermore, swelling patterns of the microgel variants occur during cooling, revealing their thermal response as a highly heterogeneous process. These results show a novel procedure to fabricate PNIPAM microgels of any elongated 2D shape with tailored porous structure and thermoresponsiveness by introducing the cononsolvency effect during stop‐flow lithography polymerization. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) printing is dramatically improving breast reconstruction by offering customized and precise interventions at various stages of the surgical process. In preoperative planning, 3D imaging techniques, such as computer-aided design, allow the creation of detailed breast models for surgical simulation, optimizing surgical outcomes and reducing complications. During surgery, 3D printing makes it possible to customize implants and precisely shape autologous tissue flaps with customized molds and scaffolds. This not only improves the aesthetic appearance, but also conforms to the patient's natural anatomy. In addition, 3D printed scaffolds facilitate tissue engineering, potentially favoring the development and integration of autologous adipose tissue, thus avoiding implant-related complications. Postoperatively, 3D imaging allows an accurate assessment of breast volume and symmetry, which is crucial in assessing the success of reconstruction. The technology is also a key educational tool, enhancing surgeon training through realistic anatomical models and surgical simulations. As the field evolves, the integration of 3D printing with emerging technologies such as biodegradable materials and advanced imaging promises to further refine breast reconstruction techniques and outcomes. This study aims to explore the various applications of 3D printing in breast reconstruction, addressing current challenges and future opportunities. [ABSTRACT FROM AUTHOR]

Triply periodic minimal surface microarchitectures (TPMS) were developed by mathematicians and evolved in all kingdoms of living organisms. Renowned for their lightweight yet robust attributes, TPMS structures find application in diverse fields, such as the construction of satellites, aircrafts, and electric vehicles. Moreover, these microarchitectures, despite their intricate geometric patterns, demonstrate potential for application as bone substitutes, despite the inherent gothic style of natural bone microarchitecture. Here, we produced three TPMS microarchitectures, D-diamond, G-gyroid, and P-primitive, by 3D printing from hydroxyapatite. We explored their mechanical characterization and, further, implanted them to study their bone augmentation and osteoconduction potential. In terms of strength, the D-diamond and G-gyroid performed significantly better than the P-primitive. In a calvarial defect model and a calvarial bone augmentation model, where osteoconduction is determined as the extent of bony bridging of the defect and bone augmentation as the maximal vertical bone ingrowth, the G-gyroid performed significantly better than the P-primitive. No significant difference in performance was observed between the G-gyroid and D-diamond. Since, in real life, the treatment of bone deficiencies in patients comprises elements of defect bridging and bone augmentation, ceramic scaffolds with D-diamond and G-gyroid microarchitectures appear as the best choice for a TPMS-based scaffold in bone tissue engineering. [ABSTRACT FROM AUTHOR]

Scaffolds offer a three-dimensional framework supporting cell growth, proliferation, and differentiation of cells which are used to repair and regenerate tissues. Recent advancements in scaffold technology have significantly exploited the field of tissue engineering and regenerative medicine. This comprehensive review provides in-depth exploration of scaffold materials, fabrication techniques, and their recent progress in applications. Composite scaffolds have promising applications in bone and dental tissue regeneration due to their greater mechanical properties and ability to promote cell growth. The inherent crosslinking present in hydrogels allows them to maintain their integrity and three-dimensional structure without dissolving. However, there is a growing interest in smart hydrogels which can respond to changes in their external surroundings like pH, ionic strength, temperature, or specific molecules. dECM scaffold is an alternative potential technique for reconstructing the functional organs/tissues by excluding the cell-associated antigens while maintaining the native ECM compositions like growth factors, basement membrane structural proteins, and GAG's. The degree of porosity in scaffolds can be increased by various fabrication techniques such as TIPS, SCPL, gas foaming, and freeze drying. GelMA hydrogels have shown promising potential in cell proliferation and tissue regeneration. In addition, graphene and its derivatives have been instrumental in the fabrication of bioactive scaffolds for cartilage regeneration. The introduction of additive manufacturing technologies, specifically 3D bioprinting, has significantly improved the precision and control of scaffold fabrication. [ABSTRACT FROM AUTHOR]

Conducting polymer scaffolds are ideal architectures for interfacing with biological systems, demonstrating great potential for integration in the next generation of bioelectronic devices. Conducting polymer scaffolds can promote cell adhesion and proliferation, whereas in certain types of cells they can promote gene expression and differentiation. Conducting polymer scaffolds have shown great potential for use in implants and biomedical devices due to their electrical properties and biocompatibility. Conducting polymer scaffolds can be engineered for controlled drug delivery for targeted therapies. Conducting polymer (CP) scaffolds have emerged as a transformative tool in bioelectronics and bioengineering, advancing the ability to interface with biological systems. Their unique combination of electrical conductivity, tailorability, and biocompatibility surpasses the capabilities of traditional nonconducting scaffolds while granting them access to the realm of bioelectronics. This review examines recent developments in CP scaffolds, focusing on material and device advancements, as well as their interplay with biological systems. We highlight applications for monitoring, tissue stimulation, and drug delivery and discuss perspectives and challenges currently faced for their ultimate translation and clinical implementation. [ABSTRACT FROM AUTHOR]

In exploring the challenges of bone repair and regeneration, this review evaluates the potential of bone tissue engineering (BTE) as a viable alternative to traditional methods, such as autografts and allografts. Key developments in biomaterials and scaffold fabrication techniques, such as additive manufacturing and cell and bioactive molecule-laden scaffolds, are discussed, along with the integration of bio-responsive scaffolds, which can respond to physical and chemical stimuli. These advancements collectively aim to mimic the natural microenvironment of bone, thereby enhancing osteogenesis and facilitating the formation of new tissue. Through a comprehensive combination of in vitro and in vivo studies, we scrutinize the biocompatibility, osteoinductivity, and osteoconductivity of these engineered scaffolds, as well as their interactions with critical cellular players in bone healing processes. Findings from scaffold fabrication techniques and bio-responsive scaffolds indicate that incorporating nanostructured materials and bioactive compounds is particularly effective in promoting the recruitment and differentiation of osteoprogenitor cells. The therapeutic potential of these advanced biomaterials in clinical settings is widely recognized and the paper advocates continued research into multi-responsive scaffold systems. [ABSTRACT FROM AUTHOR]

The piezoelectric property and biocompatibility of barium titanate (BTO) is exceptional, whereas its biological activity is limited. Bioactive glasses (BG) are widely recognized for osteoinductive bioactivities. Hence, it is meaningful to explore the reasonable design of BTO and BG combinations to achieve bioactive piezoelectric tissue engineering scaffolds that mimic natural bone. In this study, homogeneous core-shell particles of BTO wrapped in BG layer were firstly fabricated via a sol-gel process. Various BG weight ratios (5 wt%, 10 wt%, and 15 wt%) in BTO@BG particles have been able to achieve the shell thickness in the range of 4 nm–16 nm. Furthermore, the composite particles were three-dimensionally printed into porous scaffolds through gas extrusion using polyvinyl pyrrolidone as binders. The composite scaffolds have been extensively characterized with respect to their physical and functional properties. Desirable piezoelectric scaffolds (BTO@15BG-S) with compressive strength at ∼66 MPa, and piezoelectric constant (d 33) of ∼1.1 pC/N were obtained after sintering and polarization. Our findings indicated that higher sintering temperatures led to denser scaffolds with reduced porosity, increased compressive strength and higher d 33 constant. Additionally, an increase in the amount of BG coating promoted scaffold calcination via melt filling in pores, while reduced the piezoelectric constant d 33. Among all scaffolds, BTO@15BG-S exhibited superior ability to induce apatite formation when sintered at 1250 °C and soaked in simulated body fluid for 7 days. In vitro culture rat bone marrow mesenchymal stem cells (rBMSCs) and cellular assessments confirmed that polarized piezoelectric ceramic scaffolds could effectively enhance cell adhesion, proliferation, and osteogenic differentiation compared to unpolarized scaffolds. An increase in BG coating amount enhanced the capacity of piezoelectric ceramic scaffolds to upgrade osteogenesis activities of rBMSCs. These results rendered BTO@BG-S composite scaffolds promising candidate in the field of bone repair. [ABSTRACT FROM AUTHOR]

Biologization of biomaterials with endothelial cells (ECs) is an important step in vascular tissue engineering, aiming at improving hemocompatibility and diminishing the thrombo-inflammatory response of implants. Since subcellular topography in the scale of nano to micrometers can influence cellular adhesion, proliferation, and differentiation, we here investigate the effect of surface roughness on the endothelialization of gelatin hydrogel scaffolds. Considering the micron and sub-micron features of the different native tissues underlying the endothelium in the body, we carried out a biomimetic approach to replicate the surface roughness of tissues and analyzed how this impacted the adhesion and proliferation of human umbilical endothelial cells (HUVECs). Using an imprinting technique, nano and micro-roughness ranging from Sa= 402 nm to Sa= 8 μm were replicated on the surface of gelatin hydrogels. Fluorescent imaging of HUVECs on consecutive days after seeding revealed that microscale topographies negatively affect cell spreading and proliferation. By contrast, nanoscale roughnesses of Sa= 402 and Sa= 538 nm promoted endothelialization as evidenced by the formation of confluent cell monolayers with prominent VE-cadherin surface expression. Collectively, we present an affordable and flexible imprinting method to replicate surface characteristics of tissues on hydrogels and demonstrate how nanoscale roughness positively supports their endothelialization. [ABSTRACT FROM AUTHOR]

The choice of sterilization method for hydrogels used for cell culture influences the ease of preparing the gel. We prepared interpenetrating gelatin/calcium alginate hydrogels containing 1% (w/v) alginate and 1–16% (w/v) gelatin by molding with the mixture of gelatin/sodium alginate solution, followed by the addition of calcium ions by incubation in calcium chloride solution. It is the simplest method to prepare autoclavable gelatin/sodium hydrogel. We measured various properties of the hydrogels including volume, Young's modulus in the compression test, storage modulus, and loss modulus in the dynamic viscoelasticity measurement. The gelatin/alginate hydrogel can be easily fabricated into any shape by this method. After autoclave treatment, the hydrogel was shrunk to smaller than the original shape in similar figures. The shape of the gelatin/alginate hydrogel can be designed into any shape with the reduction ratio of the volume. Human osteosarcoma (HOS) cells adhered to the gelatin/alginate hydrogel and then proliferated. Gelatin/calcium alginate hydrogels with a high concentration are considered to be autoclavable culture substrates because of their low deformation and gelatin elution rate after autoclaving and the high amount of cells attached to the hydrogels. [Display omitted] • We prepared an autoclavable gelatin/alginate hydrogel by molding. • The gelatin/alginate hydrogel can be designed to any 2D/3D shape. • The gelatin/alginate hydrogel has good cell adhesion property and heat stability. • The gelatin/alginate hydrogel is useful as a scaffold in tissue engineering. [ABSTRACT FROM AUTHOR]

A challenge in tissue engineering and the pharmaceutical sector is the development of controlled local release of drugs that raise issues when systemic administration is applied. Strontium is an example of an effective anti-osteoporotic agent, used in treating osteoporosis due to both anti-resorptive and anabolic mechanisms of action. Designing bone scaffolds with a higher capability of promoting bone regeneration is a topical research subject. In this study, we developed composite multi-layer three-dimensional (3D) scaffolds for bone tissue engineering based on nano-hydroxyapatite (HA), Sr-containing nano-hydroxyapatite (SrHA), and poly-ε-caprolactone (PCL) through the material extrusion fabrication technique. Previously obtained HA and SrHA with various Sr content were used for the composite material. The chemical, morphological, and biocompatibility properties of the 3D-printed scaffolds obtained using HA/SrHA and PCL were investigated. The 3D composite scaffolds showed good cytocompatibility and osteogenic potential, which is specifically recommended in applications when faster mineralization is needed, such as osteoporosis treatment. [ABSTRACT FROM AUTHOR]

Recently, 3D-printed biodegradable scaffolds have shown great potential for bone repair in critical-size fractures. The differentiation of the cells on a scaffold is impacted among other factors by the surface deformation of the scaffold due to mechanical loading and the wall shear stresses imposed by the interstitial fluid flow. These factors are in turn significantly affected by the material properties, the geometry of the scaffold, as well as the loading and flow conditions. In this work, a numerical framework is proposed to study the influence of these factors on the expected osteochondral cell differentiation. The considered scaffold is rectangular with a 0/90 lay-down pattern and a four-layered strut made of polylactic acid with a 5% steel particle content. The distribution of the different types of cells on the scaffold surface is estimated through a scalar stimulus, calculated by using a mechanobioregulatory model. To reduce the simulation time for the computation of the stimulus, a probabilistic machine learning (ML)-based reduced-order model (ROM) is proposed. Then, a sensitivity analysis is performed using the Shapley additive explanations to examine the contribution of the various parameters to the framework stimulus predictions. In a final step, a multiobjective optimization procedure is implemented using genetic algorithms and the ROM, aiming to identify the material parameters and loading conditions that maximize the percentage of surface area populated by bone cells while minimizing the area corresponding to the other types of cells and the resorption condition. The results of the performed analysis highlight the potential of using ROMs for the scaffold design, by dramatically reducing the simulation time while enabling the efficient implementation of sensitivity analysis and optimization procedures. [ABSTRACT FROM AUTHOR]

Extensive research and practical applications have been conducted within the biomaterials domain, focusing on polylactic acid (PLA) based composite. These composites have been explored for their favorable attributes, such as excellent processability, biodegradability, and bioactivity properties, but still lack mechanical properties. In this work, PLA-based nanocomposites were prepared by incorporating hydroxyapatite (HA) and graphene oxide (GO) via melt mixing (extruder). Filaments were obtained to develop scaffolds through 3D printing, utilizing the fused deposition method (FDM). The GO was produced using Hummer’s method and characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Raman Spectroscopy. The composites were analyzed using Fourier-transform infrared spectroscopy (FTIR), molecular weight, contact angle measurements, and thermal, mechanical, and rheological analysis. Adding only 0.05 wt% of GO to both PLA and PLA/HA resulted in enhancements in mechanical properties, particularly tensile strength, and significantly modified the surface properties of the materials studied. Specifically, formulation involving PLA/HA/GO was the only one to exhibit rheological properties compatible with the scaffold production process via FDM. These specific formulations were also investigated regarding cytotoxicity, and the presence of GO induces good cytocompatibility in mouse osteoblast cells (MC3T3). These results suggest that FDM technology can be used to fabricate higher-performance (mechanical and biological) scaffolds for tissue engineering. [ABSTRACT FROM AUTHOR]

Background: Multilayered osteochondral scaffolds are becoming increasingly utilized for the repair of knee joint surface lesions (KJSLs). However, the literature on predictive factors is rather limited. Purpose: To (1) evaluate the clinical outcomes and safety of a combined single-step approach using a biomimetic collagen-hydroxyapatite scaffold (CHAS) and filtered bone marrow aspirate (fBMA) for the treatment of KJSLs and (2) identify significant predictors of the treatment outcomes. Study Design: Case series; Level of evidence, 4. Methods: All patients who underwent surgery because of a KJSL (size ≥1.5 cm2; International Cartilage Regeneration & Joint Preservation Society grades 3-4) using the combination above were selected from a hospital registry database (100 patients; minimum 2-year follow-up). Patient characteristics, medical history, knee joint and lesion status, intraoperative details, and cellular parameters of the injected fBMA were collected. The arthroscopic evaluation of chondral and meniscal tissue quality in all knee compartments was performed using the Chondropenia Severity Score. Treatment outcomes were determined clinically using patient-reported outcome measures (Knee Injury and Osteoarthritis Outcome Score, EuroQol–5 Dimensions–3 Levels, EuroQol–Visual Analog Scale, and Tegner Activity Scale) and by assessing the occurrence of serious adverse events and graft failure. Multivariable regression analysis was performed to identify significant predictors of the treatment outcomes. Results: At a mean follow-up of 54.2 ± 19.4 months, 78 (87%) patients completed the questionnaires with significant improvements toward the baseline (P <.00625): KOOS Pain subscale from 62 ± 17 to 79 ± 18, KOOS Total score from 57 ± 16 to 70 ± 20, EuroQol–Visual Analog Scale from 61 ± 21 to 76 ± 16, EuroQol–5 Dimensions–3 Levels from 0.57 ± 0.20 to 0.80 ± 0.21, and Tegner Activity Scale from 2.8 ± 1.5 to 3.9 ± 1.9. The graft failure rate was 4%. A longer duration of preoperative symptoms, previous surgery, larger lesions, older age, and female sex were the main negative predictors for the treatment outcomes. The Chondropenia Severity Score and the number of fibroblast colony-forming units in fBMA positively influenced some of the clinical results and safety. Conclusion: A CHAS augmented with fBMA proved to be an adequate and safe approach for the treatment of KJSLs up to midterm follow-up. Based on the subanalysis of predictive factors, the surgical intervention should be performed in a timely and precise manner to prevent lesion enlargement, deterioration of the general knee cartilage status, and recurrent surgical procedures, especially in older and female patients. When a CHAS is used, the quantity of MSCs seems to play a role in augmentation. Registration: NCT06078072 (ClinicalTrials.gov identifier). [ABSTRACT FROM AUTHOR]

Background: The tendon-bone interface (TBI) in the rotator cuff has a poor intrinsic capacity for healing, which increases the risk of retear after rotator cuff repair (RCR). However, facilitating regeneration of the TBI still remains a great clinical challenge. Herein, the authors established a novel strategy based on magnetic seeding to enhance the TBI regeneration. Hypothesis: Magnetic seeding bone marrow mesenchymal stem cells labeled with superparamagnetic iron oxide (SPIO-BMSCs) into a biphasic scaffold can promote tendon-bone healing after RCR. Study Design: Controlled laboratory study. Methods: BMSCs were labeled with SPIOs. Prussian blue staining, CCK-8 tests, Western blot, and quantitative reverse transcription polymerase chain reaction (PCR) were used to determine the optimal effect concentration of SPIOs on cell bioactivities and abilities. Then SPIO-BMSCs were magnetically seeded into a biphasic scaffold under a magnetic field. The seeding efficacy was assessed by a scanning electron microscope, and the potential mechanism in chondrogenic differentiation after seeding SPIO-BMSCs into the scaffold was evaluated by Western blot and PCR. Furthermore, the effect of SPIO-BMSC/biphasic scaffold on tendon-bone healing after RCR using a rat model was examined using histological analysis, enzyme-linked immunosorbent assay, and biomechanical evaluation. Results: BMSCs labeled with 100 μg/mL SPIO had no effect on cell bioactivities and the ability of chondrogenic differentiation. SPIO-BMSCs were magnetically seeded into a biphasic scaffold, which offered a high seeding efficacy to enhance chondrogenic differentiation of SPIO-BMSCs via the CDR1as/miR-7/FGF2 pathway for TBI formation in vitro. Furthermore, in vivo application of the biphasic scaffold with magnetically seeded SPIO-BMSCs showed their regenerative potential, indicating that they could significantly accelerate and promote TBI healing with superior biomechanical properties after RCR in a rat rotator cuff tear model. Conclusion: Magnetically seeding SPIO-BMSCs into a biphasic scaffold enhanced seeding efficacy to promote cell distribution and condensation. This construct enhanced the chondrogenesis process via the CDR1as/miR-7/FGF2 pathway and further promoted tendon-bone healing after RCR in a rat rotator cuff tear model. Clinical Relevance: This study provides an alternative strategy for improving TBI healing after RCR. [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: 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: Natural bone morphogenetic protein 2 disperses and degrades rapidly in vivo, reducing local concentration and therapeutic efficacy. Simply combining bone morphogenetic protein 2 with tissue engineering scaffolds could not stay in vivo for a long time, making it difficult to achieve good sustained and controlled release effects. OBJECTIVE: To prepare and test the biological properties and chondrogenic induction effect of collagen-binding domain-bone morphogenetic protein 2-collagen cartilage scaffold. METHODS: SD rat tail collagen was extracted and a collagen cartilage scaffold was prepared using a vacuum freeze-drying machine chemical crosslinking method. The plasmid expressing collagen-binding domain-bone morphogenetic protein 2 was constructed by rapid cloning C112 homologous recombination, constructed by genetic engineering, and introduced into E. coli, and then collagen-binding domain-bone morphogenetic protein 2 was isolated and purified. Natural bone morphogenetic protein 2 and collagen-binding domain-bone morphogenetic protein 2 were combined with collagen cartilage scaffolds, respectively, to detect the release level of bone morphogenetic protein 2 in the scaffolds. The biocompatibility of collagen-binding domain-bone morphogenetic protein 2-collagen cartilage scaffold was detected by CCK-8 assay and F-Actin staining. Bone marrow mesenchymal stem cells were implanted on two kinds of collagen cartilage scaffolds for chondrogenic induction, and their chondrogenic induction activity was tested. RESULTS AND CONCLUSION: (1) The binding rate of collagen-binding domain-bone morphogenetic protein 2 to collagen cartilage scaffolds was higher than that of natural bone morphogenetic protein 2 (P < 0.05). After being immersed in PBS for 7 days in vitro, the release of bone morphogenetic protein 2 in the collagen-binding domain bone morphogenetic protein 2-collagen cartilage scaffold was smaller than that in the natural bone morphogenetic protein 2-collagen cartilage scaffold (P < 0.05). The results of the CCK-8 assay and F-Actin staining showed that the collagen-binding domain-bone morphogenetic protein 2-collagen cartilage scaffold had no obvious cytotoxicity and had good biocompatibility. (2) After 14 days of chondrogenic induction, ELISA detection demonstrated that the expressions of agglutincan and type II collagen A1 in the collagen-binding domain-bone morphogenetic protein 2-collagen cartilage scaffold group were higher than those in the natural bone morphogenetic protein 2-collagen cartilage scaffold group (P < 0.05). Under scanning electron microscopy, more bone marrow mesenchymal stem cells were observed on the inner wall of the pores of the two groups of scaffolds, and the cell morphology and size were the same, and the cells were closely arranged, without cell fragmentation or abnormal morphology. (3) The results indicate that the collagen-binding domain-bone morphogenetic protein 2-collagen cartilage scaffold has good biological properties and chondrogenic induction activity. [ABSTRACT FROM AUTHOR]

BACKGROUND: In recent years, there have been many novel tympanic membrane repair materials, including patches and 3D-printed scaffolds. However, the tympanic membrane repaired by these materials is different from the natural tympanic membrane in terms of thickness and internal structure. OBJECTIVE: To explore the efficacy of bone marrow mesenchymal stem cells-loaded high-porosity polycaprolactone/collagen nanofiber membrane scaffolds in repairing chronic tympanic membrane perforation. METHODS: Polycaprolactone, polycaprolactone-collagen, and high-porosity polycaprolactone-collagen nanofiber membranes were prepared by electrospinning technology, and the surface morphology, porosity and cell compatibility of the scaffolds were characterized. The tympanic membrane perforation model of 50 male SD rats was established by puncturing the posterior lower part of both eardrums with a sterile 23-measure needle combined with mitomycin C and hydrocortisone. After 12 weeks of modeling, the rats were divided into five groups by the random number table method. The blank control group did not receive any treatment. In the other four groups, polycaprolactone nanofiber membrane (polycaprolactone group), polycaprolactone-collagen nanofiber membrane (polycaprolactone-collagen group), high-porosity polycaprolactone-collagen nanofiber membrane (high-porosity polycaprolactone-collagen group) and high-porosity polycaprolactone-collagen nanofiber membrane containing bone marrow mesenchymal stem cells (high-porosity polycaprolactone-collagen group) were implanted at the perforation of the tympanic membrane, respectively. Each group consisted of 10 animals. The healing of the tympanic membrane was examined by otoendoscopy after 1, 2, 3 and 4 weeks of stent implantation. Hematoxylin-eosin staining, Masson staining, and Ki-67 immunohistochemical staining were performed on the tympanic membrane after 4 weeks of implantation. RESULTS AND CONCLUSION: (1) Scaffold characterization: Scanning electron microscopy showed that compared with other nanofiber membranes, the highporosity polycaprolactone-collagen nanofiber membranes had more orderly nanofiber structure, larger surface pore size, and higher porosity (P < 0.001). Live/ dead staining showed that bone marrow mesenchymal stem cells adhered well on the three scaffolds, and the number of living cells on the high-porosity polycaprolactone-collagen nanofiber membrane was more than that on the other two scaffolds. Almarin staining showed that the proliferation rate of bone marrow mesenchymal stem cells on the high-porosity polycaprolactone-collagen nanofiber membrane was higher than that of the other two fiber membranes. (2) Animal experiments: Except for the blank control group, the tympanic membrane of the other four groups healed gradually with the extension of the time of fibrous membrane implantation, among which the healing speed of the cell-loaded high-porosity polycaprolactone-collagen group was the fastest. Hematoxylin-eosin staining, Masson staining, and Ki-67 immunohistochemical staining showed that the tympanic membrane of rats in the cell-carrying highporosity polycaprolactone-collagen group was moderate in thickness and a three-layer structure with uniform collagen fiber layers, similar to the normal tympanic membrane, and the repair quality of tympanic membrane was better than that of other fiber membrane groups. (3) The results showed that the high-porosity polycaprolactone-collagen nanofiber membrane containing bone marrow mesenchymal stem cells could not only rapidly repair the perforation of the tympanic membrane, but also the newly healed tympanic membrane was similar to normal tympanic membrane in structure and thickness. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) printing is an emerging technology for the construction of complex 3D constructs used for tissue engineering applications. In this study, we are proposing the preparation of 3D printing hydrogel inks consisting of the synthetic polymers poly(caprolactone) and poly(lactic acid), the biopolymer chitosan, and naturally derived gelatin. In addition, pluronic F-127 was used to improve the miscibility between the hydrophobic and hydrophilic components due to its amphiphilic character, as well as for its good 3D printability. The printability of the hydrogel inks was optimized by varying the composition, the extrusion nozzle, and the temperature, while the integrity of the 3D scaffolds was secured via sol–gel transition. The produced hydrogels with PCL-pluronic-chitosan-gelatin/15-20-4-2 wt% (PC3.75-Pl5-CG) and PLA-pluronic-chitosan-gelatin/10-20-4-2 wt% (PL2.5-Pl5-CG) presented the best printability, producing smooth and uniform porous scaffolds. The prepared hydrogels were formed via the interactions between the polymers through hydrogen bonding. Additionally, the produced hydrogels exhibited temperature-dependent swelling behavior, and the scaffolds with PCL presented lower swelling capacity than the scaffolds with PLA. The produced scaffolds presented slower hydrolyzation rate in simulated body fluid (SBF) at 25 °C compared to 37 °C. Biological studies proved that the 3D-printed porous scaffolds were non-cytotoxic and promoted human adipose-derived mesenchymal stem cell adhesion. [ABSTRACT FROM AUTHOR]

In the field of metal-based bone tissue engineering scaffolds, porous Zn-based scaffolds are expected to be one of the most promising biodegradable bone tissue engineering scaffolds due to their acceptable biocompatibility and more suitable degradation rate compared with Mg-based and Fe-based scaffolds. However, the poor mechanical strength of porous pure Zn scaffolds limits their clinical applications. To improve the mechanical properties of porous Zn scaffolds, alloying treatment has become a feasible method. In this work, porous Zn-Mg-Y alloy scaffolds were prepared by an air pressure infiltration (API) method using NaCl particles as spacing holders. The phase structures, microstructures, compressive mechanical properties, degradation properties, antibacterial abilities as well as cytotoxicity of the obtained porous Zn-Mg-Y alloy scaffolds were investigated. The experimental results suggest that the alloy scaffolds contain strengthening phases such as MgZn2 and/or Mg2Zn11 as well as Y-rich phases. Under the action of these strengthening phases, the porous Zn-Mg-Y alloy scaffolds exhibit better mechanical properties. In vitro degradation tests indicate that the strengthening phases such as MgZn2 and Mg2Zn11 in the alloy scaffolds can be preferentially degraded as sacrificial anodes. Correspondingly, the degradation rates of the porous Zn-Mg-Y alloy scaffolds in simulated body fluid (SBF) have been accelerated. Antibacterial tests imply that the porous Zn-Mg-Y alloy scaffolds possess excellent antibacterial ability against Escherichia coli similar to the porous pure Zn scaffolds. Cytotoxicity tests show that the Zn2+ concentrations in the 100% extracts prepared from the porous Zn-Mg-Y alloy scaffolds (not including Zn-3Mg-0.5Y alloy scaffold) were all lower than that prepared from the porous pure Zn scaffold. The 25% and 10% extracts prepared from all the porous Zn-Mg-Y alloy scaffolds exhibit excellent cellular activity on MC3T3-E1 cells. In summary, the porous Zn-Mg-Y alloy scaffolds have the potential to be used as bone tissue engineering scaffolds to withstand relatively large loads. [ABSTRACT FROM AUTHOR]

Invasive graft biopsies assess the efficacy of immunosuppression through lagging indicators of transplant rejection. We report on a microporous scaffold implant as a minimally invasive immunological niche to assay rejection before graft injury. Adoptive transfer of T cells into Rag2-/- mice with mismatched allografts induced acute cellular allograft rejection (ACAR), with subsequent validation in wild-type animals. Following murine heart or skin transplantation, scaffold implants accumulate predominantly innate immune cells. The scaffold enables frequent biopsy, and gene expression analyses identified biomarkers of ACAR before clinical signs of graft injury. This gene signature distinguishes ACAR and immunodeficient respiratory infection before injury onset, indicating the specificity of the biomarkers to differentiate ACAR from other inflammatory insult. Overall, this implantable scaffold enables remote evaluation of the early risk of rejection, which could potentially be used to reduce the frequency of routine graft biopsy, reduce toxicities by personalizing immunosuppression, and prolong transplant life. [ABSTRACT FROM AUTHOR]

In the development of bone graft substitutes, a fundamental step is the use of scaffolds with adequate composition and architecture capable of providing support in regenerative processes both on the tissue scale, where adequate resistance to mechanical stress is required, as well as at the cellular level where compliant chemical–physical and mechanical properties can promote cellular activity. In this study, based on a previous optimization study of this group, the potential of a three-dimensional construct based on polycaprolactone (PCL) and a novel biocompatible Mg- and Sr-containing glass named BGMS10 was explored. Fourier-transform infrared spectroscopy and scanning electron microscopy showed the inclusion of BGMS10 in the scaffold structure. Mesenchymal stem cells cultured on both PCL and PCL-BGMS10 showed similar tendencies in terms of osteogenic differentiation; however, no significant differences were found between the two scaffold types. This circumstance can be explained via X-ray microtomography and atomic force microscopy analyses, which correlated the spatial distribution of the BGMS10 within the bulk with the elastic properties and topography at the cell scale. In conclusion, our study highlights the importance of multidisciplinary approaches to understand the relationship between design parameters, material properties, and cellular response in polymer composites, which is crucial for the development and design of scaffolds for bone regeneration. [ABSTRACT FROM AUTHOR]

Additive manufacturing has been widely used for producing porous titanium orthopedic implants. However, the higher surface area inherent to porous structures increases the risk of bacterial colonization. In this work, composite scaffolds with dual functions of the antibacterial and osteogenesis promotion properties are developed. The porous titanium is fabricated using a selective laser melting process to provide mechanical support. Silk fibrin (SF) sponge‐loading gentamicin and extracellular vesicles (EVs) are prepared in the pores of the porous titanium. The developed composite scaffolds are investigated for their antibacterial and osteogenesis effects. The samples exhibit well antibacterial activity against Escherichia coli. The samples also show good cytocompatibility, effectively promoting the adhesion and proliferation of the bone marrow mesenchymal stem cells (rBMSCs). EVs significantly promote the expression of osteogenesis‐related genes in rBMCSs and the superior extracellular matrix mineralization reveals that EVs have a remarkable role in enhancing osteogenic differentiation. Therefore, the composite scaffolds with dual functions of antibacterial and osteogenesis promotion properties have excellent potential for orthopedic implant applications. [ABSTRACT FROM AUTHOR]

The evaluation of nanostructured biomaterials and medicines is associated with 2D cultures that provide insight into biological mechanisms at the molecular level, while critical aspects of the tumor microenvironment (TME) are provided by the study of animal xenograft models. More realistic models that can histologically reproduce human tumors are provided by tissue engineering methods of co-culturing cells of varied phenotypes to provide 3D tumor spheroids that recapitulate the dynamic TME in 3D matrices. The novel approaches of creating 3D tumor models are combined with tumor tissue engineering (TTE) scaffolds including hydrogels, bioprinted materials, decellularized tissues, fibrous and nanostructured matrices. This review focuses on the use of nanostructured materials in cancer therapy and regeneration, and the development of realistic models for studying TME molecular and immune characteristics. Tissue regeneration is an important aspect of TTE scaffolds used for restoring the normal function of the tissues, while providing cancer treatment. Thus, this article reports recent advancements in the development of 3D TTE models for antitumor drug screening, studying tumor metastasis, and tissue regeneration. Also, this review identifies the significant opportunities of using 3D TTE scaffolds in the evaluation of the immunological mechanisms and processes involved in the application of immunotherapies. [ABSTRACT FROM AUTHOR]