OBJECTIVE: From the point of view of material science, the methods of tissue repair and defect reconstruct were discussed, including mesenchymal stem cells (MSCs), growth factors, gene therapy and tissue engineered tissue. METHODS: The advances in tissue engineering technologies were introduced based on the recent literature. RESULTS: Tissue engineering should solve the design and preparation of molecular scaffold, tissue vascularization and dynamic culture of cell on the scaffolds in vitro. CONCLUSION: Biomaterials play an important role in the tissue engineering. They can be used as the matrices of MSCs, the delivery carrier of growth factor, the culture scaffold of cell in bioreactors and delivery carrier of gene encoding growth factors.
OBJECTIVE: To study the feasibility of the formation of allogeneic tissue-engineered cartilage of certain shape in immunocompetent animal using the injectable biomaterial. METHODS: Fresh newborn rabbits’ articular cartilages were obtained under sterile condition (lt; 6 hours after death) and incubated in the sterile 0.3% type II collagenase solution. After digestion of 8 to 12 hours, the solution was filtered through a 150 micron nylon mesh and centrifuged, then the chondrocytes were washed twice with phosphate buffered saline (PBS) and mixed with the biomaterial to create a final cell density of 5 x 107/ml. The cell-biomaterial admixture was injected into rabbits subcutaneously 0.3 ml each point while we drew the needle back in order to form the neocartilage in the shape of cudgel, and the control groups were injected with only the biomaterial or the suspension of chondrocytes with the density of 5 x 10(7)/ml. After 4, 6, 8 and 12 weeks, the neocartilages were harvested to analyze. RESULTS: The new nodes could be touched subcutaneously after 2 weeks. In the sections of the samples harvested after 4 weeks, it was found that the matrix secreted and the collagen formed. After 6 weeks and later than that, the neocartilages were mature and the biomaterial was almost completely degraded. The cudgel-shaped samples of neocartilage could be formed by injection. In the experiment group, there was no obvious immune rejection response. On the contrary, there were no neocartilage formed in the control group. CONCLUSION: The injectable biomaterial is a relatively ideal biomaterial for tissue engineering, and it is feasible to form allogeneic tissue engineered cartilage of certain shape by injection in an immunocompetent animal.
OBJECTIVE: To review the advance in materials of nerve conduit and Schwann cell transplantation for preparation of artificial nerve with tissue engineering technique. METHODS: Recent literatures about artificial nerve, nerve conduit and Schwann cell transplantation were extensively reviewed. RESULTS: Many biomaterials such as silicon, dacron, expanded polytetrafluoroethylene(ePTFE), polyester and chitin could be used as nerve conduits to repair nerve defect, the degradable biomaterials were better. The nerve conduit with intrinsic filaments could be used to bridge an extended gap in peripheral nerve. Purified and cultured Schwann cells were still bioactive. Axonal regeneration could be enhanced after implantation of Schwann cells into nerve conduit. CONCLUSION: The ideal artificial nerve is composed of three dimensional biodegradable nerve conduit and bioactive Schwann cells, Schwann cells can be distributed in nerve conduit just like Bünger’s band.
Objective To evaluate the biocompatibility of a new bone matrix material (NBM) composed of both organic and inorganic materials for bone tissue engineering. Methods Osteoblasts combined with NBM in vitro were cultured. The morphological characteristics was observed; cell proliferation, protein content and basic alkaline phosphatase(ALP) activity were measured. NBM combined with osteoblasts were implanted into the skeletal muscles of rabbits and the osteogenic potential of NBM was evaluated through contraat microscope, scanning electromicroscope and histological examination. In vitro osteoblasts could attach and proliferate well in the NBM, secreting lots of extracellular matrix; NBM did not cause the inhibition of proliferation and ALP activity of osteoblasts. While in vivo experiment of the NBM with osteoblasts showed that a large number of lymphacytes and phagocytes invading into the inner of the material in the rabbit skeletalmuscle were seen after 4 weeks of implantation and that no new bone formation was observed after 8 weeks. Conclusion This biocompat ibility difference between in vitro and in vivo may be due to the immunogenity of NBM which causes cellular immuno reaction so as to destroy the osteogenic environment. The immunoreaction between the host and the organic-inorganic composite materials in tissue engineering should be paid more attention to.
Objective To sum up the recent progress of common bone graft substitute and to forecast the possible directions for further research. Methods Recent original articles about investigation and appl ication for bone graft substitute were extensively reviewed. Several common bone graft substitutes were selected and expounded in different categories. Results Bone graft was an essential treatment in order to provide structural support, fill bone cavity and promote bone defect heal ing. The gold standard for bone graft was autograft which is subject to many restrictions. In recent years, theresearch and development of bone graft substitute have received publ ic attention. A very great progress has been made in the research and appl ication of allograft bones, synthetic bones and engineered bones, and some research results have been put into use for real products. Conclusion There still exist many problems in present bone graft substitutes. Combining various biomaterials and using the specific processing technology to develop a biomaterial which has the similar mechanical and chemical properties and physical structures to autograft so as to promote bone defect heal ing is the direction for future research.
Objective To introduce the development of dextran-based hydrogel and its drug delivery system in drug sustained and/or controlled release, and to investigate their application in tissue engineering.Methods Related literature was extensively reviewed and comprehensively analyzed. Results In recent years, great progress was made in the studies of dextran-based hydrogels and study on dextran-based intelligent materials became an investigative hotspot especially in tissue engineering. Conclusion Dextran based hydrogel is considered to be a good potential material in field of drug delivery and tissue engineering. Endowed with new characteristics, a series of intelligent biomaterials can be derived from dextran-based hydrogels, which can be widely used in biomedicine. Further study should be done on the industrialization of its interrelated production.
Objective To study the past, present and future of bone grafting. Methods Related l iterature on bone grafting in recent years was extensively reviewed. Results Bone grafting had a history over 300 years, a variety of bone grafting candidates including autografting, allografting, xenografting, synthetic and composite bone grafting had been util ized in cl inical orthopedics at present. But bone autografting and allografting represented the preferred alternatives for bone grafting.It would be important trend in bone grafting to fulfill the optimizing design of biomaterials and constructing composite bone substitutes with cells, factors and scaffolds. Conclusion The future bone grafting might be focused on how to achieve the goal of the rapid osseointegration as well as the physiological bone reconstruction.
Membrane guided tissue regeneration is new biological concept. The basic theory of this concept includes the belief that during the healing process of wound, the different cells will show different speed of cell migration and regeneration in the wound. If an appropriate membrane being placed to form a mechanical barrier, so that only the needed cells can grow into that area and prevent others from going in, thus resulting in the creation of a guided area where the needed cells can undergo proliferation and differentiation under protection in completing an ideal tissue regeneration and repair. In this article, the experimental researches on the application of membrane guided tissue regeneration in the repair of tubular bone defects, skull defects and faciomaxillary defects were reviewed from literatures, and the degradable and non-degradable materials were introduced, particularly. The pros and cons of this method and the materials were evaluated. It is believed that this technique will push forward the progress in bone biology and reconstructive surgery.
Objective To investigate the latest development of tissue engineeredregenerative medicine in industrialization, with the intention to direct work in practical area. Methods A complete insight of regenerative medicine in industrialization was obtained through referring to update publications, visiting related websites, as well as learning from practical experience. Results The aerial view of the future of regenerative medicine was got based on knowledge of four different tissue engineering projects. Conclusion All present efforts should be devoted to regenerative medicine area meeting the industrialized trends.
ObjectiveTo summarize the developments of oxygen-generating materials as biomaterials and its applications in tissue engineering. MethodsThe recent literature on oxygen-generating materials as biomaterials was extensively reviewed, illustrating the properties and applications of oxygen-generating materials in tissue engineering. ResultsOxygen-generating materials as biomaterials have good biocompatibility and degradability. It supports the cell adhesion differentiation and growth. It is used for repairing liver, pancreas, myocardium, and so on. After modification, oxygen-generating materials can be extensively used in tissue engineering. ConclusionOxygen-generating materials is a good biomaterial, which has a great potential applications in tissue engineering.