| There is special compact structure lack of nutritional support from blood vessels,nerves and lymphoid tissue in articular cartilage. As a result, it is difficult to repairthemselves when they are damaged by trauma, degeneration, infection and injuries causedby other factors. Recently, there is deficiency without satisfactory repair results in allkinds of therapies of articular cartilage injuries，such as limited resources, secondaryimmunologic rejection and fibrous cartilage repair lack of mechanical properties ofhyaline cartilage. However, the continuous progresses in tissue engineering andregenerative medicine have provided novel strategies in cartilage repair and regeneration.Bone marrow mesenchymal stem cells (BMSCs) have been regarded as one of perfectseed cells in cartilage tissue engineering with the advantages of self proliferation andmultiple differentiations，easy to harvest and culture，and without serious rejections. Theprocess of articular cartilage repair mainly is that BMSCs are induced into chondrocytesby multiple growth factors in special microenvironment. Induction to chondrocytes bysingle growth factor is expensive and unsatisfactory. So, the combined application of multiple growth factors in cartilage tissue engineering has been paid attention.Platelet-rich fibrin (PRF) can be prepared by centrifugation of autologous blood. There arehigh concentration of platelets, multiple growth factors and fibrin in the platelet gel, inwhich the fibrin is connected with growth factors by chemical bond and can release themslowly to prolong the action time.Part1: Effect of autologous platelet-rich fibrin on chondrogenic differentiation ofrabbit bone marrow mesenchymal stem cellsObjective: To investigate the effect of autologous platelet rich fibrin (PRF) onchondrogenic differentiation of rabbit bone marrow mesenchymal stem cells (BMSCs) invitro. Methods: Blood extracted from rabbit’s heart was used to prepare PRF, and theultrastmcture of PRF was observed by electron microscope. BMSCs were isolated andcultured ex vivo. BMSCs at passage3were divided into two groups： PRF group andpositive control group. After2weeks of culture, the morphology of cells in each groupwere observed by phase-contrast microscope, the phenotype was identified with safranin0staining，toluidine blue staining，HE staining and collagen II immunocytochemistry，andthe gene expression levels of SOX9，collagen type II and Aggrecan were detected byReal-time PCR. Results: Phase-contrast microscope showed that inducing BMSCs of PRFgroup and positive control group grew form long spindle to tirangle, polygon, andcircle.safranin0staining，toluidine blue staining，HE staining and collagen IIimmunocytochemistry of two groups were positive, gene expression levels of SOX9,collagen type II and Aggrecan were high, there was no statistical difference between twogroups (P>0.05). Conclusion: PRF could promote chondrogenic differentiation ofBMSCs in vitroJt can be used as autologous biological materials, and it will play animportant role in constructing tissue engineering cartilage.Part2: Study on the repair of full thickness defect in rabbit knee-joint cartilage byautologous Platelet-rich ifbrinObjective: To explore the effect of autologous platelet rich fibrin (PRF) on the repair of full thickness defect in rabbit knee-joint cartilage. Methods: Blood extracted from’rabbits heart was used to prepare PRF，and the PRF membrane was transplanted into thefull thickness defect in rabbit knee-joint cartilage. The rabbits were euthanized to collectspecimen12weeks and24weeks after the operation. The general observation,biomechanical performances analysis, tissue staining, immunohistological staining andbiochemical components analysis were applied to evaluate the repair results of theneonatal cartilage. Results: The general observation indicates a satisfactory repair effectand the neonatal cartilage is smooth on the surface. The general observation scale,Biochemical components analysis, II collagen and it’s mRNA expression in the neonatalcartilage in PRF Group are better than the blank group, with statistical significancebetween multiple comparisons (P <0.05). Comparing to the normal catrilage，there are nostatistical significance in the neonatal cartilage24weeks after the operation(尸>0.05).The cartilage tissue staining, including safranin0staining, toluiding blue staining andII collagen immunohistological staining indicate positive expression, and the structure andmorphology are better than that in the blank group. Especially24weeks after theoperation, the structure and morphology are similar to the normal cartilage surrounded.Conclusion: PRF can effectively repair the full thickness defect in rabbit knee-jointcartilage and has a good prospect in cartilage repair clinically.Brief summary: In this study, autologous PRF, prepared by the Choukroun methods,was mixed with BMSCs ex vivo and induced them into chondrocytes. The results indicatethat PRF is a good autologous biomaterials for scaffold because the growth factors inwhich can be released slowly according to the ratio of internal environment. The assays ofPRF membrane repair of full thickness defect in rabbit knee-joint cartilage indicate thatPRF can effectively repair the full thickness defect in rabbit knee-joint cartilage and has agood prospect in cartilage repair clinically. |
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