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 investigate cell cycle as a new tool to evaluate the biocompatibility of biomaterials.Methods The cell cycle and the expression of related genes were analyzed by the methods of immunocytochemistry, protein blotting, RT PCR and flow cytometry. Results The physical properteis, chemical properties and topological properities of biomaterials could not only influence cell cycle of the cells attached onto biomaterials but also affect the expression of related genes of target cells. Conclusion As an important extension of routine proliferation epxeriments, the study of cell cycle control will be great help for us to to study the cell group as an organic society. It revealed the balance between cell proliferation, cell differentiation and apotosis. It is suggested that the study of cell cycle control will play a key role in the research of tissue engineering.
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.
ObjectiveTo study the effect of intercellular adhesion (ica) operon of Staphylococcus epidermidis on the inflammation associated with mixed biofilm of Staphylococcus epidermidis and Candida albicans on endotracheal tube material in rabbits. MethodsThe standard strains of Staphylococcus epidermidis RP62A (ica operon positive, positive group) and ATCC12228 (ica operon negative, negative group) were taken to prepare a bacterial solution with a concentration of 1×106 CFU/mL, respectively. Then, the two bacterial solutions were mixed with the standard strain of Candida albicans ATCC10231 of the same concentration to prepare a mixed culture solution at a ratio of 1∶1, respectively. The mixed culture solution was incubated with endotracheal tube material for 24 hours. The formation of mixed biofilm on the surface of the material was observed by scanning electron microscope. Thirty New Zealand rabbits, aged 4-6 months, were divided into two groups (n=15), and the endotracheal tube materials of the positive group and the negative group that were incubated for 24 hours were implanted beside the trachea. The body mass of rabbits in the two groups was measured before operation and at 1, 3, and 7 days after operation. At 1, 3, and 7 days after operation, the levels of interleukin 1β (IL-1β), IL-6, tumor necrosis factor α (TNF-α), and monocytechemotactic protein 1 (MCP-1) were detected by using an ELISA test kit. At 7 days after operation, the formation of mixed biofilm on the surface of the endotracheal tube materials was observed by scanning electron microscope, the inflammation and infiltration of tissues around the materials were observed by HE staining, and the bacterial infections in heart, lung, liver, and kidney were observed by plate colony counting method.ResultsScanning electron microscope observation showed that the mixed biofilm structure was obvious in the positive group after 24 hours in vitro incubation, but no mixed biofilm formation was observed in the negative group. In vivo studies showed that there was no significant difference in body mass between the two groups before operation and at 1, 3, and 7 days after operation (P>0.05). Compared with the negative group, the levels of MCP-1 and IL-1β at 1 day, and the levels of IL-1β, MCP-1, IL-6, and TNF-α at 3 and 7 days in the positive group all increased, with significant differences (P<0.05). Scanning electron microscope observation showed that a large amount of Staphylococcus epidermis and mixed biofilm structure were observed in the positive group, and a very small amount of bacteria was observed in the negative group with no mixed biofilm structure. HE staining of surrounding tissue showed inflammatory cell infiltration in both groups, and neutrophils and lymphocytes were more in the positive group than in the negative group. There was no significant difference in the number of bacterial infections in heart and liver between the two groups (P>0.05). The number of bacterial infections in lung and kidney in the positive group was higher than that in negative group (P<0.05).ConclusionIn the mixed infection of Staphylococcus epidermidis and Candida albicans, the ica operon may strengthen the structure of the biofilm and the spread of the biofilm in vivo, leading to increased inflammatory factors, and the bacteria are difficult to remove and persist.
Objective To review research progress of corneal tissueengineering.Methods The recent articles on corneal tissue engineering focus on source and selection of corneal cells, the effects of growth factors on culture of corneal cells in vitro. The preparation and selection of three-dimensional biomaterial scaffolds and their b and weak points were discussed. Results The corneal tissue engineering cells come from normal human corneal cells. The embryo corneal cell was excellent. Several kinds of growth factors play important roles in culture, growth and proliferation of corneal cell, and incroporated into matrix.Growth factors including basic fibroblast growth factor, keratinocyte growth factor, transforming growth factor β1 and epidermal growth factor was favor to corneal cell. Collagen, chitosan and glycosaninoglycans were chosen as biomaterial scaffolds. Conclusion Human tissue engineering cornea can be reconstructed and transplanted. It has good tissue compatibility and can be used as human corneal equivalents.
OBJECTIVE: To discuss the approaches of tissue engineered blood vessels (TEBV) reconstruction. METHODS: The recent literatures about TEBV were widely reviewed. We summarized various types of biomaterials served as scaffold for TEBV and evaluated the construction model of TEBV. And the biological properties of some TEBV were compared. RESULTS: Although the final model of construction of TEBV was not clear, reports in the last two years had shown several important advances in this exciting field. CONCLUSION: Mimicry of some or all of the properties of three layers of natural healthy blood vessels has been the strategy of all TEBV approaches.
Objective To investigate the influence of the exogenouscollagen on the function of cells in construction of artificial biotendon.Methods Three materials including human hair, carbon fiber(CF) and polyglycolic acid (PGA) were combined with exogenous collagen and co-cultured with standard transferred human embryonic tenocytes at a concentration of 3×106/mm3 in vitro. The cell number and morphology were observed under inverted microscope and scanning electron microscope after 2 hours, 3 days and 5 days.Results In the artificial biotendon combined with collagen, the cells concentrated around the materials and the cells adhering to the materials turned into round after 2 hours. After 3 days, the adhering cells increased. After 5 days, the shape of the cells changed from round to spindle.ConclusionExogenous collagen will facilitate the cells to adhere onto materials and proliferate.
Objective To review the recent progress of the small intestinal submucosa (SIS) in application research of tissue repair and reconstruction. Methods The domestic and international articles on the SIS were reviewed and summarized. Results As a natural extracellular matrix, SIS has outstanding biological advantages, such as good mechanical property, tissue compatibility, and lower immunogenicity. SIS has been used to repair and reconstruct various types of tissue defects in animal models and clinical application, especially in the treatment of hernia, urinary system disease, and refractory skin trauma. The development of the tissue engineering technology expands the field of SIS repair and reconstruction and promotes the intensive study of SIS. However, the long-term effect of SIS in tissue repair and reconstruction still remains to be further observation, while the cell/SIS material construction by tissue engineering technology also needs more studies. Conclusion SIS has a widely promising application future in the tissue repair and reconstruction.
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 review and evaluate the extensive and further research and the application of the collagenbased biomaterials in the field of clinical medicine. Methods The clinical research and application of collagen-based biomaterials were comprehensively reviewed and evaluated on the basis of the up-to-date publications and our practical experiences in their studies and manufacturing. Results The following five aspects concerned with the collagen-based biomaterials were evaluated: biological property, quality control, formulation of substrate and clinical application, immunogenicity and clinical side effect, and potential of the market development. Conclusion Collgen-based biomaterials have a great potential and market space in their clinical application.