Studies On Processing And Characterization Of Composite Transplant Collagen Dermal Scaffold

Extensive skin burn, traumatic injury, skin ulcer and other skin defects would cause skin dysfunction and even threaten to patient's life if they were severe. It should not only be timely and permanent coverage, but also reach the goal of functional and cosmetic restoration of skin to treat skin defects. It was difficult to achieve both of them by traditional treatment methods. The establishment of skin tissue engineering supplied a new clue and method to improve the wound healing quality, solve the shortage of skin source and so on. Composite skin was a new permanent wound dressing, which had many advantages, such as good elasticity, fine wear resistance, good tensile strength, skin texture likely and so on, so it became a research hotspot recently. The dermal substitutes which were the base of the composite skin and the bottleneck of composite grafting influenced not only the biological effect and efficacy of keratinocytes, but also the outcome of repair. In recent years many kinds of dermal substitutes had been developed, in which acellular dermal matrix (ADM) had been the research focus. Because the limitation of ideas and the defects of preparing technology, ADM had many shortcomings, such as strong immunogenicity, bad permeability, low biological activity and so on.The thesis was guided by the principle of tissue engineering, combined with chemistry and chemical, biomedical engineering, leather science and engineering, material science. On the base of previous research, the study was focused on the influence of cross-linking and compounding on the performance of new type collagen scaffold, and then the method and technique of the preparation was optimized to determine the preparation process of a new composite transplant collagen dermal scaffold, which was developed by adopting various chemical, biological and physical comprehensive methods to deal with suckling pigskin. The major research contents in this paper were listed as follow:(1) The cross-linking conditions of glutaraldehyde (GA) and EDC were optimized, and the influences of cross-linking on the degradation, tensile strength and so on were studied. Results show that: The shrinkage temperature rises with the increase of crosslinker dosage; The tensile strength of EDC-treated samples does not change significantly, and that of GA-treated samples has a light increase; The degradation time of EDC-treated samples increases lightly higher than that of GA-treated samples; The swelling of samples cross-linked by the two cross-linkers declines significant; The fibroblast proliferation is significantly better in the EDC-treated samples than that in the GA-treated samples.(2) The compounding conditions were optimized, and the compounding effects on the performance of scaffold were studied. Results show that: The polysaccharide, such as chondroitin sulfate can maintain a long time to ensure that they can play their role better in scaffold; The compounding can increase the tensile strength and extend the degradation time, but the effect is not significant; The chitooligosaccharides, chondroitin sulfate and hyaluronic acid compounding can effectively enhance the cell adhesion, but the heparin compounding can not.(3) According to the principle of tissue engineering and the research results of (1), (2), combining with the advantages of existing materials and the requirements of ideal dermal scaffold, a new composite transplant collagen dermal scaffold was prepared, and its major performance including physical property, biocompatibility and so on were studied systematically. Results show that: The surface of sample is smooth and glossy, and the fibers woven closely; Its tensile-strength is between 10.65MPa and 10.87MPa,which demonstrates it has better tensile strength; The degradation time is between 20h and 50h, which can be controlled by changing treatment process; The permeability is around 3000 g·m^-2·24h^-1 ; The porosity is between 87% and 93%; The collagenous interstitial fibers of composite transplant collagen dermal scaffold has been removed completely; SEM results illustrate that collagen fiber bundles maintains its original structure and be appropriate loose, and the scaffold has rich internal porous structure; It has good bioactivity, and can accelerate cells adhesion. The composite transplant collagen dermal scaffold, whose interfibrillary substance among the dermis, such as epidermis, fat cell, mucoprotein ect. was removed to weaken the antigen of the collagen, was cross-linked by EDC and compounded with biological active substance, such as chondroitin sulfate, chitooligosaccharides, fibroblast growth factor and so on. And it has high permeability, good biological activity and suitable degradation time, so it is expected to be used as auto-dermal complex transplant dermal scaffolds.