Experimental Study On The Repair Of Articular Cartilage Defects With Periosteal Cover Induced Bone Marrow Mesenchymal Stem Cells In Rabbits

Objectives To experiment an effective approach for repair and regeneration of articular cartilage defects using tissue engineering approaches,and to help the clinical repair and regeneration of articular cartilage injures. We implanted the induced rabbit bone mesenchymal stem cells into full-thickness defects of articular cartilage in the medial condyle of the distal femur and covered with periosteum to retain the cells at the defect site;the Contralateral defects were covered with periosteum only or leave them untreated as contral. The experiment was to study the effects of implanting the induced BMSCs into the defects of articular cartilage with periosteum covering.Methods Bone marrow aspirated from New Zealand white rabbits was cultured in plastic culture bottles and the BMSCs were isolate at the same time. BMSCs were cultured and multiplied in vitro, TGF-β₁ was used to induce chondrogenic differentiation of BMSCs at high density culture(1×10⁶/ml).The induced cells were implanted into ostochondral defects in the medial condyle of the distal femur, in the control groups, the defects were covered with periosteum only or left untreated. The new repair tissue were examed grossly, histologically for chondrocyte mRNA and protein expression at the end of 6 weeks and 12 weeks. Results from these histomorphometric studies were compared by analysis of variance (ANOVA).Results BMSCs were isolated gradually during the culture process and had a similar spindle-like morphology, the cells cultured in vitro experienced latent phase , logarithmic growth phase and plateau phase. BMSCs were chondrogenesis induced by TGF-β₁ in high density, verified by positive results of immunohistochemistry and in situ hybridization. In the experimental group, the defects were filled with hyaline-like cartilage at the end of 6 weeks, the new repairing cartilage and the subchodral bone were remodeled at the end of 12 weeks. The expression of type II collagen in the repair tissue was verified by immunohistochemistry and in situ hybridization. In the control groups, the defects were repaired with caitilage tissue at different degree. There was an apparent difference between the experimental group and the two control groups with Wakitani histological grading system.Conclusions The combination of the whole bone marrow culture and the adhere culture is an effective method to isolate BMSCs from bone marrow aspirate.TGF-β₁ can induce the chondrogenenic differentiation of high density cultured BMSCs. Implanting the induced BMSCs into the ostochondral defects and covering with periosteum to retain the cells at the defects site can promote the repair of the defects, it may be a promising method for clinical treatment of articular cartilage injures.