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Objective The impact of stent design on venous patency is not well studied. The purpose of this study was to investigate the effect of stent material burden on endothelial coverage of stented venous segments, which may contribute to vessel healing and patency. Methods Segmented self expanding bare nitinol stents (18 × 50 mm) comprising 5 mm long attached metallic rings separated by 2, 5, or 8 mm gaps were implanted in the inferior vena cava (IVC) of 10 sheep. These stents were designed and manufactured for the purposes of this study. At six, 12, and 24 weeks after implantation the animals were euthanised and the stented vessels harvested for histomorphometric analysis. Three sections from the metallic part as well as the gaps between the struts were reviewed for quantification of endothelialisation after six, 12, and 24 weeks. The intimal thickness over and between the stent struts was measured. The endothelialisation score (graded from 1 for complete luminal endothelialisation to 5 for absence of endothelial cells) was determined. Results All stents were successfully deployed and all 10 sheep survived until the time of harvesting. Macroscopic inspection after 24 weeks showed only partial endothelialisation over stents with 2 mm and 5 mm skipped segments, whereas the stents with 8 mm skipped segments were totally incorporated into the vein wall. After 24 weeks, the mean (SD) neointimal thicknesses over stent struts with 2 mm, 5 mm, and 8 mm skipped segments were 254.0 (51.6), 182.2 (98.1), and 194.6 (101.1) μm, respectively. Comparison of endothelialisation scores of stents over time showed statistically significantly better endothelialisation over stents with 8 mm gaps after 12 and 24 weeks. Conclusion Stent designs providing structural support to veins with larger gaps between the scaffold material appear to lead to faster and more complete endothelialisation as well as a thinner intimal layer.

Silk fibroin produced from silkworms has been intensively utilized as a scaffold material for a variety of biotechnological applications owing to its remarkable mechanical strength, extensibility, biocompatibility, and ease of biofunctionalization. In this research, we engineered silk as a novel trap platform capable of capturing microorganisms. Specifically, we first fabricated the silk material into a silk sponge by lyophilization, yielding a 3D scaffold with porous microstructures. The sponge stability in water was significantly improved by ethanol treatment with elevated β-sheet content and crystallinity of silk. Next, we biofunctionalized the silk sponge with a poly-specific microbial targeting molecule, ApoH (apolipoprotein H), to enable a novel silk-based microbial trap. The recombinant ApoH engineered with an additional penta-tyrosine was assembled onto the silk sponge through the horseradish peroxidase (HRP) mediated dityrosine cross-linking. Last, the ApoH-decorated silk sponge was demonstrated to be functional in capturing our model microorganism targets, E. coli and norovirus-like particles. We envision that this biofabricated silk platform, capable of trapping a variety of microbial entities, could serve as a versatile scaffold for rapid isolation and enrichment of microbial samples toward future diagnostics and therapeutics. This strategy, in turn, can expedite advancing future biodevices with functionality and sustainability.

Calcification of bioprosthetics is a primary challenge in the field of artificial heart valves and a main reason for biological heart valve prostheses failure. Recent advances in nanomaterial science have promoted the development of polymers with advantageous properties that are likely suitable for artificial heart valves. In this work, we developed a nanocomposite polymeric biomaterial POSS-PEG (polyhedral oligomeric silsesquioxane-polyethylene glycol) hybrid hydrogel, which not only has improved mechanical and surface properties but also excellent biocompatibility. The results of atomic force microscopy and in vivo animal experiments indicated that the content of POSS in the PEG matrix plays an important role on the surface and contributes to its biological properties, compared to the decellularized porcine aortic valve scaffold. Additionally, this modification leads to enhanced protection of the hydrogel from thrombosis. Furthermore, the introduction of POSS nanoparticles also gives the hydrogel a better calcification resistance efficacy, which was confirmed through in vitro tests and animal experiments. These findings indicate that POSS-PEG hybrid hydrogel is a potential material for functional heart valve prosthetics, and the use of POSS nanocomposites in artificial valves may offer potential long-term performance and durability advantages.

Previous studies have proved that fibrin is an excellent scaffold material for tissue engineered blood vessel. However, the mechanical properties of fibrin are not enough. One way to solve the problem is to combine polymer materials with fibrin to enhance its biomechanical properties. In this study, a novel polycaprolactone (PCL)/fibrin composite scaffold was prepared by electrospinning technology. The morphological, physicochemical analysis, blood compatibility, biomechanical properties, biocompatibility and biodegradability of this vascular scaffold were evaluated. The results showed that electrospun PCL/fibrin scaffold possessed smaller aperture and larger fiber diameter than that of fibrin scaffold. The swelling ratio of the vascular PCL/fibrin scaffold at (0:100), (10:90), (20:80) and (30:70) was 112 ± 5.3, 103 ± 6.9, 94 ± 5.9 and 89 ± 3.4%, respectively. Mechanical properties of fibrin scaffolds were enhanced significantly by the addition of PCL. Furthermore, the time of plasma re-calcification, activated partial thromboplastin time and thromboplastin time in four different proportions of PCL/fibrin scaffolds were similar to that of the control group. Degradation experiments

Engineered cardiac patches (ECPs) hold great promise to repair ischemia-induced damages to the myocardium. Recent studies have provided robust technological advances in obtaining pure cardiac cell populations as well as various novel scaffold materials to generate engineered cardiac tissues that can significantly improve electrical and contractile functions of damaged myocardium. Given the significance in understanding the cellular and extracellular structural as well as compositional details of native human heart wall, in order to fabricate most suitable scaffold material for cardiac patches, herein, we have reviewed the structure of the human pericardium and heart wall as well as the compositional details of cardiac extracellular matrix (ECM). Moreover, several strategies to obtain cardiac-specific scaffold materials have been reviewed, including natural, synthetic and hybrid hydrogels, electrospun fibers, decellularized native tissues or whole organs, and scaffolds derived from engineered cell sheets. This review provides a comprehensive analysis of different scaffold materials for engineering cardiac tissues.

Three-dimensional biodegradable porous scaffolds play an important role in tissue engineering. The degradable scaffold material, based on 1,4-butanediamine-modified poly(lactide-co-glycolide) (BMPL...

Biomaterials are a cornerstone technology of the biomedical device, tissue engineering, and regenerative medicine industries. While traditional biomaterials are fully defined synthetics, growing evidence supports the use of extracellular matrix-based biomaterials produced through the decellularization of organs, tissues, or cell cultures. These materials are particularly advantageous as they largely retain the structure and the biochemical nature of the original tissue, properties that are often difficult to reproduce with synthetics. Indeed, there are many FDA-approved and clinically used extracellular matrix-based materials that are generated through decellularization processes. In this review, we first describe methods of decellularization used to produce these materials and their associated advantages and limitations, discuss the current use of extracellular matrix-based materials in regenerative engineering applications, describe the areas where current research is occurring, and forecast areas where impactful research may appear. The regeneration of tissues often requires a scaffold material to support and guide the cells that are performing the repair. Often, these materials are manmade and lack many of the key features present in native tissue. However, a tissue can be processed to remove its cells (a process called decellularization), leaving behind a scaffold of proteins and polysaccharides known as the extracellular matrix. These decellularized matrices are attractive scaffolds for use in regenerative medicine applications, and they are the subject of this review.

A slowly degradable bone scaffold can well maintain the balance between new bone regeneration and scaffold resorption, esp. for seniors or patients suffering from pathological diseases, because too fast degradation can lead to the loss of long-term biological stability and result in scaffold failure. In this present study, calcium phosphate silicate (CPS) and polydimethylsiloxane (PDMS) were blended in different ratios to formulate slurries for scaffold fabrication. The effects of crosslinked PDMS on the CPS material properties were first characterized and the most viable formulation of CPS-PDMS slurry was determined based on the aforementioned results to 3D fabricate scaffolds. The biocompatibility of CPS-PDMS was further evaluated based on the scaffold extract’s cytotoxicity to osteoblast cells. Furthermore, real-time PCR was used to investigate the effects of scaffold extract to increase osteoblast proliferation. It is showed that the crosslinked PDMS interfered with CPS hydration and reduced both setting rate and compressive strength of CPS. In addition, CPS porosity was also found to increase with PDMS due to uneven water distribution as a result of increased hydrophobicity. Degradation and mineralization studies show that CPS-PDMS scaffold was slowly degradable and induced apatite formation. In addition, the in vitro analyses show that the CPS-PDMS scaffold did not exert any cytotoxic effect on osteoblast cells but could improve the cell proliferation via the TGFβ/BMP signaling pathway. In conclusion, CPS-PDMS scaffold is proved to be slowly degradable and biocompatible. Further analyses are therefore needed to demonstrate CPS-PDMS scaffold applications in bone regeneration.

An increasing incidence of the bone damage either due to trauma or a wide range of diseases related to bone necessitates the advent of new technologies or modification of the existing pattern of treatment to deliver utmost care to an individual thereby helping them to lead a normal and healthy life. Revolutionary changes in the field of tissue engineering (TE) pave a way from repair to regeneration of human tissues and restoring the health of an individual. Among the numerous biomaterials available, hydrogel emerges as a promising source of scaffold material in the field of bone TE (BTE). This article presents an overview on hydrogels and their role in BTE.

Decellularized extracellular matrix (dECM) is widely used in regenerative medicine as a scaffold material due to its unique biological activity and good biocompatibility. Hydrogel is a three-dimensional network structure polymer with high water content and high swelling that can simulate the water environment of human tissues, has good biocompatibility, and can exchange nutrients, oxygen, and waste with cells. At present, hydrogel is the ideal biological material for tissue engineering. In recent years, rapid development of the hydrogel theory and technology and progress in the use of dECM to form hydrogels have attracted considerable attention to dECM hydrogels as an innovative method for tissue engineering and regenerative medicine. This article introduces the classification of hydrogels, and focuses on the history and formation of dECM hydrogels, the source of dECM, the application of dECM hydrogels in tissue engineering and the commercial application of dECM materials.

Tissue engineering advancements have seen a multitude of findings in several disciplines, including cell biology, imaging, characterization of cell–material and cell–cell interactions, and also novel biomaterial research. The main aim of tissue engineering, however, remains as a tool to restore, maintain, or improve defective tissue functions. The paradigm of this concept is threefold: (1) Isolation of cells, (2) Seeding of cells into the appropriate 3D scaffolds, and (3) Providing the appropriate growth factors and physical and mechanical conditions in-vitro thereby mimicking the native conditions conducive for cell and tissue growth. The development of the 3D scaffold or matrix is by far the most challenging aspect wherein the choice of the scaffold material, its biocompatibility, cell–material interactions, its biodegradation and bioresorption properties, all play a major role. Polymers have been a mainstay as scaffold material for such applications. Both synthetic and natural polymers have been used as matrices for cell and tissue growth. The main aim in development of polymeric scaffold for tissue engineering is that it should resemble the properties of the tissues native extracellular matrix. A lot of advancements have been made in the last 10 years in the area of polymers used for tissue engineering applications and this chapter aims to provide a comprehensive coverage of the field.

This review focuses on the potential of polyvinylidene fluoride (PVDF) as tissue scaffolding materials. PVDF is defined in terms of the synthesis mechanisms and the method of the β phase formation process. General properties are fundamentally discussed in terms of their wettability and electroactive characteristics, which play an essential role in modifying other potential materials for tissue-based applications. The latest technologies for the replacement of artificial tissue scaffolds are evaluated, and the applications of PVDF-based scaffolds are discussed.

In cartilage tissue engineering, research on materials for three-dimensional (3D) scaffold has attracted attention. Decellularized matrix can be one of the candidates for the scaffold material. In this study, decellularization of regenerated cartilage was carried out and its effectiveness as a scaffold material was examined. Three-dimensionally-cultured cartilage constructs in the differentiation medium containing IGF-1 produced more cartilage matrix than those in the proliferation medium. Detergent-enzymatic method (DEM) could decellularize 3D-cultured cartilage constructs only by 1 cycle without breaking down the structure of the constructs. In vitro, newly-seeded chondrocytes were infiltrated and engrafted into decellularized constructs in the proliferation medium, and newly formed fibers were observed around the surface where newly-seeded cells were attached. Recellularized constructs could mature similarly as those without decellularization in vivo. The decellularized 3D-cultured matrix from regenerative cartilage is expected to be used as a scaffold material in the future.

In this review, few established cell printing techniques along with their parameters that affect the cell viability during bioprinting are considered. 3D bioprinting is developed on the principle of additive manufacturing using biomaterial inks and bioinks. Different bioprinting methods impose few challenges on cell printing such as shear stress, mechanical impact, heat, laser radiation, etc., which eventually lead to cell death. These factors also cause alteration of cells phenotype, recoverable or irrecoverable damages to the cells. Such challenges are not addressed in detail in the literature and scientific reports. Hence, this review presents a detailed discussion of several cellular bioprinting methods and their process-related impacts on cell viability, followed by probable mitigation techniques. Most of the printable bioinks encompass cells within hydrogel as scaffold material to avoid the direct exposure of the harsh printing environment on cells. However, the advantages of printing with scaffold-free cellular aggregates over cell-laden hydrogels have emerged very recently. Henceforth, optimal and favorable crosslinking mechanisms providing structural rigidity to the cell-laden printed constructs with ideal cell differentiation and proliferation, are discussed for improved understanding of cell printing methods for the future of organ printing and transplantation.

Interests in in vitro skin models have been growing. Collagen, which is a main scaffold material for in vitro 3D skin models, has weak mechanical properties, often resulting in undesirable contraction. The physiological characteristics of the skin models often depend on the matrix in which cells are cultured. In this study, we developed a 3D skin model using gelatin methacrylate. The mechanical and transport properties were studied, and attachment and growth of fibroblasts and keratinocytes were examined. Fibroblasts preferred softer matrix, whereas HaCaT cells preferred harder matrix of gelatin methacrylate. This study provides information for developing in vitro skin models.

This paper aims to evaluate the mechanical behaviour of a bioresorbable polymeric coronary scaffold using finite element method, focusing on scaffold-artery interaction during degradation and vessel remodelling. A series of nonlinear stress-strain responses was constructed to match the experimental measurement of radial stiffness and strength for polymeric scaffolds over 2-year in-vitro degradation times. Degradation process was modelled by incorporating the change of material property as a function of time. Vessel remodelling was realised by changing the size of artery-plaque system manually, according to the clinical data in literature. Over degradation times, stress on the scaffold tended to increase firstly and then decreased gradually, corresponding to the changing yield stress of the scaffold material; whereas the stress on the plaque and arterial layers showed a continuous decrease. In addition, stress reduction was also observed for scaffold, plaque and artery in the simulations with the consideration of vessel remodelling. For the first time, the work offered insights into mechanical interaction between a bioresorbable scaffold and blood vessel during two-year in-vitro degradation, which has significance in assisting with further development of bioresorbable implants for treating cardiovascular diseases.

The Lando® dermal scaffold is a newly developed, tissue-engineered dermal scaffold material. This study sought to observe its vascularization in an acute full-thickness skin-defect porcine model. T...

Bioglass® 45S5 (BG) has an outstanding ability to bond with bones and soft tissues, but its application as a load-bearing scaffold material is restricted due to its inherent brittleness. BG-based composites combine the amazing biological and bioactive characteristics of BG with structural and functional features of other materials. This article reviews the composites of Bioglass® in combination with metals, ceramics and polymers for a wide range of potential applications from bone scaffolds to nerve regeneration. Bioglass® also possesses angiogenic and antibacterial properties in addition to its very high bioactivity; hence, composite materials developed for these applications are also discussed. BG-based composites with polymer matrices have been developed for a wide variety of soft tissue engineering. This review focuses on the research that suggests the suitability of BG-based composites as a scaffold material for hard and soft tissues engineering. Composite production techniques have a direct influence on the bioactivity and mechanical behavior of scaffolds. A detailed discussion of the bioactivity, in vitro and in vivo biocompatibility and biodegradation is presented as a function of materials and its processing techniques. Finally, an outlook for future research is also proposed. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3197-3223, 2017.

Carboxymethyl Chitosan (CMCh) is a semi-synthetic derivative of chitosan (a natural biopolymer) with increasing biomedical applications as a matrix or scaffold material for tissue engineering appli...

Three-dimensional bioprinting can prove to be a promising technology for bone tissue regeneration as it facilitates good spatio-temporal distribution of cells in scaffold. The feed for bioprinting is bioink, which comprises of cells incorporated in the scaffold material. Progress has been made on the incorporation of growth factors in the bioink, which not only enables efficient regeneration but at the same time proves the feasibility of large constructs. Important parameters which determine the suitability of bioink have been discussed here. Lack of vascularization limits the success of this technology in its present form. Advances in inducing vascularization and growth factors have also been discussed. Towards the end, challenges and opinions in the area of bioprinting of bone tissue regeneration have been presented.

Three dimensional (3D) bioprinting technology enables the freeform fabrication of complex constructs from various hydrogels and is receiving increasing attention in tissue engineering. The objective of this study is to develop a novel self-supporting direct hydrogel printing approach to extrude complex 3D hydrogel composite structures in air without the help of a support bath. Laponite, a member of the smectite mineral family, is investigated to serve as an internal scaffold material for the direct printing of hydrogel composite structures in air. In the proposed printing approach, due to its yield-stress property, Laponite nanoclay can be easily extruded through a nozzle as a liquid and self-supported after extrusion as a solid. Its unique crystal structure with positive and negative charges enables it to be mixed with many chemically and physically cross-linked hydrogels, which makes it an ideal internal scaffold material for the fabrication of various hydrogel structures. By mixing Laponite nanoclay with various hydrogel precursors, the hydrogel composites retain their self-supporting capacity and can be printed into 3D structures directly in air and retain their shapes before cross-linking. Then, the whole structures are solidified in situ by applying suitable cross-linking stimuli. The addition of Laponite nanoclay can effectively improve the mechanical and biological properties of hydrogel composites. Specifically, the addition of Laponite nanoclay results in a significant increase in the Young's modulus of each hydrogel-Laponite composite: 1.9-fold increase for the poly(ethylene glycol) diacrylate (PEGDA)-Laponite composite, 7.4-fold increase for the alginate-Laponite composite, and 3.3-fold increase for the gelatin-Laponite composite.

Tissue engineering has the potential to regenerate tissue which regeneration capacity is limited. Nowadays, three-dimensional scaffold has become an excellent scaffold in tissue engineering. Chitosan as a scaffold material in tissue engineering is known for emerging techniques for treating some tissue damage, but there are questions that need to be answered, including application of chitosan and other materials, to provide growth factors, mechanical support and other micro environment, as well as the application at all levels, including conducive to an optimal and suitable cell source, the usability of growth factor, the selectivity of optimal biomaterial scaffolds as well as the technology for improving partial reconstruction of meniscus tears. This review focuses on current research on application of chitosan as scaffold material of construction In Vitro.

Breast cancer is the most common invasive cancer in women worldwide. Surgical removal of the breast tumor and subsequent reconstructive surgery can result in complications such as infection or necr...

This chapter discusses different types of scaffold material that can provide structural support for cells to attach, survive, and grow into a 3D tissue. These scaffold materials can include molecules that exist biologically as well as synthetic ones, yielding scaffolds with a wide range of viscoelastic properties. Depending on their chemical composition, materials used in scaffolding can be classified into four broad categories: ceramics, polymers, composites, and decellularized matrix. A list of 10 key questions to ask should aid students in selecting scaffold material for their chosen application. The second part of the chapter is devoted to the use of decellularized tissue (DCT) as the most suitable natural scaffold for tissue growth. The methods to obtain DCT are covered, including freezing and defrosting, using hypo- and hyperosmolar solutions, solvents (alcohol, methanol, chloroform, and acetone), acids and bases, chelators, enzymes, and detergents. Main effects of these various reagents on quality of DCT are discussed. The latter can be evaluated using three complementary means: the degree of remaining cellular content, the lack of detergents and salt remnants, and the integrity of ECM architecture.

Decellularization involves removal of cellular material from tissue which results in a scaffold material consisting of only the extra cellular matrix (ECM). The effect of each individual decellularizing detergent on the final ECM scaffold and how that may differ from the combined use of these detergents is currently a gap in decellularization methodologies. This study evaluates the hypothesis that a synergistic effect exists when commonly used decellularization detergents are combined. This was evaluated with regard to decellularization efficiency, tissue strength, and collagen structure. Bovine pericardium was decellularized using a combination of 0.5% sodium dodecyl sulfate (SDS), 1% sodium deoxycholate (SDC) and 1% TritonX-100, and compared to the use of each detergent individually. The combined detergent decellularization protocol showed effective decellularization (p = .004), with minimal effects on tissue strength (p = .21) and structure (p = .21). Use of detergents individually, resulted in detrimental effects on tissue structure and integrity or ineffective decellularization. This study shows a synergistic relationship between SDS, SDC and TritonX-100 when combined at specific concentrations. The use of detergents in combination instead of individually appears to be superior, as it results in less ECM damage and improved decellularization effectivity.

Three-dimensional (3D) printing of core/shell filaments allows direct fabrication of channel structures with a stable shell that is cross-linked at the interface with a liquid core. The latter is removed post-printing, leaving behind a hollow tube. Integrating an additive manufacturing technique (like the one described here with tailor-made [bio]inks, which structurally and biochemically mimic the native extracellular matrix [ECM]) is an important step towards advanced tissue engineering. However, precise fabrication of well-defined structures requires tailored fabrication strategies optimized for the material in use. Therefore, it is sensible to begin with a set-up that is customizable, simple-to-use, and compatible with a broad spectrum of materials and applications. This work presents an easy-to-manufacture core/shell nozzle with luer-compatibility to explore core/shell printing of woodpile structures, tested with a well-defined, alginate-based scaffold material formulation.

Permanent therapeutically placed implants often used in situations when regeneration or transplantation are not practical or possible. They include metallic grafts for osteosynthesis, bulk metallic glasses, ceramics, and non-resorbable polymers providing mechanical support. Repair of the tissues on micro scale can also benefit from the biocompatible permanent implants. Vascular graft engineering and repairs of the spinal cord and peripheral nerves are among the most demanding application. Carbon fibers (CF) have superior mechanical and chemical properties, however, their long-time safety was never systematically estimated. The biggest concern comes from residual polymers used for pyrolysis and epoxy laminating resins. Here we attempted to investigate survival of the cells cultured on carbon fibers and to evaluate the tissue responses towards the long-term implanted material. Immortalized rat Schwann cells displayed efficient sporadic attachment to the carbon fibers with survival rate over 90%. Carbon fiber implants in adipose and on connective tissues were tolerable by animals during about 40% of their lifespan with no signs of inflammation on physiological, morphological or gene expression level.

Bioprinting is rapidly developing into a powerful tool in tissue engineering, for both organ printing and the development of in vitro models that can be used in drug discovery, toxicology and in vitro bioreactors. Nevertheless, the ability to create complex 3D culture systems with different types of cells and extracellular matrices integrated with perfusable channels has been a challenge. Here we develop an approach that combines the xurography of a scaffold material (cellulose) with extrusion printing of bioinks onto it, followed by assembly in a layer-by-layer fashion to create complex 3D culture systems that could be used as in vitro models of biological processes. This new method, termed ExCeL, can recapitulate the complexities of natural tissues with a proper 3D distribution of cells, extracellular matrices, and different molecules, while providing the whole structure with mechanical stability, and direct and easy access to the cells, even the ones that are positioned deep in the bulk of the structure, without the need to fix or section the samples. Briefly, the bioprinting of predefined patterns with a feature size of ∼1 mm has been made possible by treating paper with the hydrogel's crosslinker and printing cell-embedded hydrogel that will solidify immediately upon contact with the paper. These impregnated layers can be used as single layers or in a layer-by-layer approach by stacking them (here up to four layers) for applications such as cell migration and proliferation in 3D structures composed of collagen or alginate. Cells are generally sensitive to the amount of FBS in their culture media and we have shown how FBS amount will effect cell migration. By cutting the paper in certain patterns, printing hydrogel on the remaining parts of it, and stacking the paper in layers, features like embedded channels are formed that will provide cells will better mass transfer in thick structures. This technique provides biologists with a unique tool to perform sophisticated in vitro assays.

As the largest organ in the human body, the skin has the function of maintaining balance and protecting from external factors such as bacteria, chemicals, and temperature. If the wound does not heal in time after skin damage, it may cause infection or life-threatening complications. In particular, medical treatment of large skin defects caused by burns or trauma remains challenging. Therefore, human bioengineered skin substitutes represent an alternative approach to treat such injuries. Based on the chemical composition and scaffold material, skin substitutes can be classified into acellular or cellular grafts, as well as natural-based or synthetic skin substitutes. Further, they can be categorized as epidermal, dermal, and composite grafts, based on the skin component they contain. This review presents the common commercially available skin substitutes and their clinical use. Moreover, the choice of an appropriate hydrogel type to prepare cell-laden skin substitutes is discussed. Additionally, we present recent advances in the field of bioengineered human skin substitutes using three-dimensional (3D) bioprinting techniques. Finally, we discuss different skin substitute developments to meet different criteria for optimal wound healing.

Lower Back Pain (LBP) is common healthproblemin societywithprevalence80-85%. One of the causes of LBP is Herniated Nucleus Pulposus (HNP). This disease occurs in intervertebral discs (IVD), supporting the spine, found a gel fluid called Nucleus pulposus (NP) at the center surrounded by 15-20 concentric thin layers of the Annulus fibrosus (AF). This gel that will come out through AF and nerve pinched behind which makes sufferer feel pain and numb. Handling HNP with physical therapy only reduce the pain and not totally cured. While the surgery use discectomy method by eliminating the protruding parts NP or in whole, but has some drawbacks, such as: high cost, wide surgical incisions, probably occurrence of bleeding or other neurological disorders. Solving problem with find new methods that are faster, easier, and more affordable, we analyze using of alginate/PVA composite with chitosan suspense as a reinforcement as hydrogel injectable material to replace NP. Independent variable is chitosan percentage each sample, as much 5; 10; 15%. This study as a purpose to know mechanical properties, biocompatible, injectable performance, viscosity of alginate/PVA/chitosan, SEM-EDX test and FTIR test. The best result got is addition chitosan 15% appropriate as NP replacement.

For tissue scaffolding, it is desirable for the scaffold to promote growth of the native tissue, before the scaffold is ultimately replaced by tissue. While polycaprolactone (PCL) is a superb scaffold material, it is impossible to non-invasively monitor its degradation. Here, incorporating fluorescent nanodiamonds into PCL, we show sub-dermal fluorescence imaging of PCL. This provides an opportunity to monitor PCL degradation to assess real-time tissue uptake and replacement. Furthermore, nanodiamonds increase the hydrophillicity PCL, and hence may increase tissue uptake rates, opening new applications for PCL.

With the advent of nanotechnology, carbon nanomaterials such as carbon nanofibers (CNF) have aroused substantial interest in various research fields, including energy storage and sensing. Further improvement of their properties might be achieved via the application of viral particles such as bacteriophages. In this report, we present a filamentous M13 bacteriophage with a point mutation in gene VII (pVII-mutant-M13) that selectively binds to the carbon nanofibers to form 3D structures. The phage-display technique was utilized for the selection of the pVII-mutant-M13 phage from the phage display peptide library. The properties of this phage make it a prospective candidate for a scaffold material for CNFs. The results for binding of CNF by mutant phage were compared with those for maternal bacteriophage (pVII-M13). The efficiency of binding between pVII-mutant-M13 and CNF is about 2 orders of magnitude higher compared to that of the pVII-M13. Binding affinity between pVII-mutant-M13 and CNF was also characterized using atomic force microscopy, scanning electron microscopy, and transmission electron microscopy, which confirmed the specificity of the interaction of the phage pVII-mutant-M13 and the CNF; the binding occurs via the phage's ending, where the mutated pVII protein is located. No similar behavior has been observed for other carbon nanomaterials such as graphite, reduced graphene oxide, single-walled carbon nanotubes, and multiwalled carbon nanotubes. Infrared spectra confirmed differences in the interaction with CNF between the pVII-mutant-M13 and the pVII-M13. Basing on conducted research, we hypothesize that the interactions are noncovalent in nature, with π-π interactions playing the dominant role. Herein, the new bioconjugate material is introduced.

Intestinal transplantation remains a life-saving option for patients with severe intestinal failure. With the advent of advanced tissue engineering techniques, great strides have been made toward manufacturing replacement tissues and organs, including the intestine, which aim to avoid transplant-related complications. The current paradigm is to seed a biocompatible support material (scaffold) with a desired cell population to generate viable replacement tissue. Although this technique has now been extended by the three-dimensional (3D) printing of geometrically complex scaffolds, the overall approach is hindered by relatively slow turnover and negative effects of residual scaffold material, which affects final clinical outcome. Methods recently developed for scaffold-free 3D bioprinting may overcome such obstacles and should allow for rapid manufacture and deployment of "bioprinted organs." Much work remains before 3D bioprinted tissues can enter clinical use. In this brief review we examine the present state and future perspectives of this nascent technology before full clinical implementation.

Thermo-sensitive methylcellulose (MC) hydrogel has been widely used as a scaffold material for biomedical applications. However, due to its poor mechanical properties, the MC-based hydrogel has rarely been employed in 3D bioprinting for tissue engineering scaffolds. In this study, the dual crosslinkable tyramine-modified MC (MC-Tyr) conjugate was prepared via a two-step synthesis, and its hydrogel showed excellent mechanical properties and printability for 3D bioprinting applications. The MC-Tyr conjugate formed a dual-crosslinked hydrogel by modulating the temperature and/or visible light. A combination of reversible physical crosslinking (thermal crosslinking) and irreversible chemical crosslinking (photocrosslinking) was used in this dual crosslinked hydrogel. Also, the photocrosslinking of MC-Tyr solution was facilitated by visible light exposure in the presence of biocompatible photoinitiators (riboflavin, RF and riboflavin 5'-monophophate, RFp). The RF and RFp were used to compare the cytotoxicity and salting-out effect of MC-Tyr hydrogel, as well as the initiation ability, based on the difference in chemical structure. Also, the influence of the printing parameters on the printed MC hydrogel was investigated. Finally, the cell-laden MC-Tyr bioink was successfully extruded into stable 3D hydrogel constructs with high resolution via a dual crosslinking strategy. Furthermore, the MC-Tyr scaffolds showed excellent cell viability and proliferation.

The repair and regeneration of large bone defects resulting from disease or trauma remains a significant clinical challenge. There has been increasing interest in using bioactive glass as a scaffold material for bone tissue engineering due to its appealing characteristics. However, the application of glass scaffolds for the repair of load-bearing bone defects is often limited by their low mechanical strength and fracture toughness. This chapter focuses on recent advances in the development and use of bioactive glass scaffolds for bone tissue engineering applications. Scaffolds with compressive strengths comparable to those of trabecular and cortical bones have been achieved using a variety of processing methods. The low fracture toughness (low resistance to fracture) and limited mechanical reliability remain key limitations for bioactive glass scaffolds. Multiple approaches to manipulate the structure and performance of bioactive glass are discussed. Future research directions including the development of strong and tough bioactive glass scaffolds and their evaluation in unloaded and load-bearing bone defects in animal models are recommended.

Healing rates after rotator cuff repair vary widely. New technologies seek to improve tendon to bone healing with the addition of platelet-rich plasma, stem cells, and biological and synthetic grafts. Platelet-rich plasma and mesenchymal stem cells are used to help create a favorable environment for tendon to bone healing, and grafts and scaffolds provide structural support for repair. The efficacy of platelet-rich plasma and stem cell products seems to be variable, with different products offering different levels of cytokine and growth factors. Scaffold material is also variable with a wide range of synthetic and biological grafts.

Purpose To compare dimensional changes and bone quality of two different grafting materials used for socket preservation. Materials and methods Thirty-three patients requiring extraction were recruited and randomly assigned to receive: biphasic calcium sulfate/ hydroxyapatite (BCS/HA); bovine derived xenograft (BDX) or no grafting (Control). Ridge width (at -3 and -6 mm) and vertical distance from a stent were measured at the time of extraction/grafting. Measurements were repeated at reentry and core biopsies were harvested. Results Baseline vertical distance for the BDX, C and BCS/HA groups were 7.45 ± 3.1, 7.69 ± 4.2, and 6.75 ± 3.5 mm, respectively (P = .830). Post-op, C group had greater vertical loss (1.71 ± 0.4 mm) compared to BCS/HA (0.65 ± 0.5) and BDX (0.25 ± 0.2 mm), P = .059. Mean baseline width at -3 mm was 8.69 ± 1.1 mm, 8.31 ± 1.4 mm, and 9.0 ± 1.1 mm, respectively (P = .509). Post-op, this width was reduced by 2.96 ± 0.3 mm (C), 1.56 ± 0.4 mm (BDX), and 0.5 ± 0.4 mm (BCS/HA), P = .001. Mean ridge width at -6 mm for the C (6.5 ± 1.7 mm) was significantly smaller than BCS/HA (7.95 ± 2.8 mm) and BDX (8.85 ± 1.9 mm), P = .043. Histologically, the BDX group had greater residual scaffold material and less vital bone compared to the BCS/HA group. Pain scores were relatively low for all groups. Conclusions BCS/HA may be used for socket preservation with similar or better results compared to BDX. The significance of greater residual scaffold found in the BDX group is yet to be determined.

This protocol describes a novel and easy net mold-based method to create three-dimensional (3-D) cardiac tissues without additional scaffold material. Human-induced pluripotent stem-cell-derived cardiomyocytes (iPSC-CMs), human cardiac fibroblasts (HCFs), and human umbilical vein endothelial cells (HUVECs) are isolated and used to generate a cell suspension with 70% iPSC-CMs, 15% HCFs, and 15% HUVECs. They are co-cultured in an ultra-low attachment "hanging drop" system, which contains micropores for condensing hundreds of spheroids at one time. The cells aggregate and spontaneously form beating spheroids after 3 days of co-culture. The spheroids are harvested, seeded into a novel mold cavity, and cultured on a shaker in the incubator. The spheroids become a mature functional tissue approximately 7 days after seeding. The resultant multilayered tissues consist of fused spheroids with satisfactory structural integrity and synchronous beating behavior. This new method has promising potential as a reproducible and cost-effective method to create engineered tissues for the treatment of heart failure in the future.

Silk fibroin is commonly used as scaffold material for tissue engineering applications. In combination with a mineralization with different calcium phosphate phases, it can also be applied as material for bone regeneration. Here, we present a study which was performed to produce mineralized silk fibroin scaffolds with controlled macroporosity. In contrast to former studies, our approach focused on a simultaneous gelation and mineralization of silk fibroin by immersion of frozen silk fibroin monoliths in acidic calcium phosphate solutions. This was achieved by thawing frozen silk fibroin monoliths in acidic calcium phosphate solution, leading to the precipitation of monocalcium phosphate within the silk fibroin matrix. In the second approach, a conversion of incorporated β-tricalcium phosphate particles into brushite was successfully achieved. Furthermore, a controlled cryostructuring process of silk fibroin scaffolds was carried out leading to the formation of parallel-oriented pores with diameters of 30–50 µm.

Ionic liquids (ILs) present many new opportunities for the field of sol–gel chemistry. When conducted in an IL medium, sol–gel chemistry can produce novel silica structures as well as hybrid materials known as ionogels, which feature ILs supported by a solid scaffold material. In this work, the influence of reactive formulation on the properties of silica-supported ionogels is reported. A simple, non-hydrolytic sol–gel reaction between tetramethoxysilane and formic acid is employed to create silica-supported ionogels that exhibit wide variations in silica content, gelation time, and mechanical character. The influence of formulation on gelation time is demonstrated, and it is shown that a range of formulations can be used to produce soft, mechanically compliant ionogels. Furthermore, either brittle or compliant ionogels can be realized via rapid- or slow-gelling formulations. It is observed that the speed of gelation influences the pore structure in the resultant silica scaffold, thereby enabling different mechanical characters to be achieved for ionogels containing equivalent silica mass fractions.

Biomimetic extracellular matrix (ECM) topographies driven by the magnetic‐field‐directed self‐assembly of ECM protein‐coated magnetic beads are fabricated. This novel bottom‐up method allows us to program isotropic, anisotropic, and diverse hybrid ECM patterns without changing other physicochemical properties of the scaffold material. It is demonstrated that this 3D anisotropic matrix is able to guide the dendritic protrusion of cells.

Scaffolds material is the key factor for bone tissue engineering, and construction of the scaffolds is also an important part. Adopting the biocompatible, biodegradable, hydroxyapatite and sodium alginate as the moulding material, using 3D printing technology, choosing different filling paths. The research based on the artificial bones which manufactured by self-developed 3D printing equipment. Then, the work measured and analysed important parameters, optimised the best filling path and re-used this path to prepare the bone scaffold for bone defect repair experiment. At different time points, we observed the situation of bone defects repair to verify whether the scaffold material has the properties of bone substitution. The paper provides a reference for the study of bone tissue engineering materials.

Biological scaffold materials derived from the extracellular matrix (ECM) of intact mammalian tissues have been successfully used in a variety of tissue engineering/regenerative medicine applications both in preclinical studies and in clinical applications. Although it is recognized that the materials have constructive remodeling properties, the mechanisms by which functional tissue restoration is achieved are not well understood. There is evidence to support essential roles for both the structural and functional characteristics of the biological scaffold materials. This paper provides an overview of the composition and structure of selected ECM scaffold materials, the effects of manufacturing methods upon the structural properties and resulting mechanical behavior of the scaffold materials, and the in vivo degradation and remodeling of ECM scaffolds with an emphasis on tissue function.

For an ideal scaffolding material, properties are required that include biocompatibility, suitable microstructure, desired mechanical strength and degradation rate as well as most importantly the ability to support cell residence and allow retention of metabolic functions. Numerous strategies currently used to engineer tissues depend on employing a material scaffold. These scaffolds serve as a synthetic extracellular matrix (ECM) to organize cells into a 3D architecture and to present stimuli, which direct the growth and formation of a desired tissue. Depending on the tissue of interest and the specific application, the required scaffold material and its properties will be quite different.

The development of tissue engineering provides a new way for the repair and reconstruction of meniscal injury. Using this technology to build a functional meniscus in the prevention of complications after meniscectomy has important significance. Because of the blood supply characteristics of the meniscus, meniscal injury caused no blood flow region do not have the ability to heal. The development of tissue engineering provides a new way for the repair and reconstruction of meniscal injury. The repair of meniscal scaffold materials more reports mainly include natural biological materials, synthetic materials, nanomaterials etc. The study of tissue engineering meniscus has achieved initial results, but are in the experimental stage of the scaffold material, there is no an ideal material. Therefore, the search for a good cell compatibility, controllable degradation rate and hot research has certain mechanical strength of scaffold materials is still the meniscus tissue engineering.

Septal reconstruction is challenging. Autologous cartilage may be thin or deviated and traditional techniques are often inadequate or technically difficult. The use of an absorbable scaffold material for support during healing can improve results. Polydioxanone (PDS) plate can be used for this purpose. We describe our use of PDS plate in both open and closed septal surgeries, as well as in the repair of septal perforations. Surgical techniques and potential complications are discussed. The current evidence for PDS plate is reviewed. PDS plate is a safe and reliable absorbable implant that has many different applications in septal surgery and reconstruction. It not only acts as a scaffold but also stimulates and guides cartilage regeneration.