The Formation Of The Allogeneic Tissue Engineered Cartilage Using Injectable Biomaterial

In otolarygngeal field there are many cases of deformities and dysfunctions due to the defects of cartilage. Doctors and scientists used to reconstruct these deformities and dysffinctions by three methods: autotransplant, allotransplant and artificial graft. However autogenous grafts are associated with problems of poor moldability, limited supply and donor- site morbidity; most alloplastic and artificial grafts fail to immune rejection response, foreign body reaction, infection and so on. Therefore, it remains a difficulty and important problem for the doctors to find a new way of the correction of the deformities and dysfunctions due to the defects of cartilage. Tissue engineering technology provides a new approach to solve these problems. Tissue engineering is a multidiscipliary science merging with the biology and engineering. Its basic idea is to expand the number of cells in vitro by cell culture, then seed them onto a polysynthetic biodegradable polymer structure, and finally implant the polymer-cell construct into animals to form functional organs or tissues. Nowadays it focuses on three research aspects: seed cell characteristics, scaffold materials and the fabrication of tissue-engineering tissue. In this study, we have studied the feasibility of the formation of allogeneic tissue engineered cartilage in inmunocompetent animal and verified that the biomaterial used in our experiment has the ideal 4 features as tissue-engineering biomaterial. Materials and Methodes Fresh newborn rabbits?articular cartilages were abtained under sterile condition. The cartilage chips were cut into 2mm X 2mm X 2mm fragments and washed twice with phosphate-buffered saline, then the cartilage fragments were incubated in the sterile 0.3% type II collagenase solution for 8-12 hours at 37擟. After digestion the solution was filtered through the sterile 100- urn nylon mesh to remove undigested fragments. Cell number and viability were determined by using a hemacytometer and the trypan blue exclusion dye test. Then the chondrocytes were mixed with the biomaterial to creat a final cell density of 5 Xl 07/ml,the resulting cell-biomaterial admixture was injected into rabbits subcutaneously, and the control groups were injected with only the biomaterial or the suspension of chondrocytes. After 4,6,8,12 weeks the neocartilages were harvested to analyze. Result In the experiment group and control groups we have not observed obvious immune rejection response. and we could touch the new nodes subcutaneously after 2 weeks. After 4 weeks we harvested the neocartilages and found they were firm to palpation, resisting mechanical compression and there were fibrous calpsules surrounding the neocartilage. The specimens harvested after 6 weeks or more than that had gross morphology similar to that of native cartilage. In the control groups, neither group consisting of chondrocytes alone nor the biomaterial implants without chondrocytes demonstrated the presence of neocartilages. With standard hematoxylin and eosin stains,Saffranin 0 stains and Masson抯 stains, specimens after 4 weeks demonstrated that the matrix secreted and the collagen formed, but the biomaterial was not degraded completely. After 6 weeks, the neocartilages were mature and the biomaterial was almost completely degraded. Conclusion...