Synovium-derived mesenchymal stem cell sheet enhance autologous osteochondral transplantation in a rabbit model

Objective: Autologous osteochondral transplantation (OCT) is an option to treat articular cartilage defects. However, poor graft integration at the cartilage defect/graft interface and secondary graft degeneration limit the use of autologous OCT. Cell sheet engineering offers hope in regenerative medicine. The purpose of this study was to evaluate the effect of synovium derived mesenchymal stem cell (SMSC) sheet on autologous OCT for (1) lateral integration and (2) graft degeneration. Method: Full-thickness osteochondral defects (3.5 mm in diameter, 3.0 mm in depth) were created at both femoral grooves of 12 rabbits. The right knees were used as the cell sheet group and the left knees were used as the control group. Osteochondral plugs were harvested when the defects were created and then were placed into their original locations with (cell sheet group) or without (control group) three-layered SMSC sheets. The animals were sacrificed at 4 and 8 weeks postoperatively (6 animals at each time point). Histological and immunohistochemical staining were used to evaluate the result. Results: Histological and immunohistochemical findings at the interface between the grafts and the original cartilage showed better integration in the cell sheet group. In addition, less graft and original cartilage degeneration were found 4 and 8 weeks after operation. The mean histological score was significantly higher in the cell sheet group. Conclusion: The animal model showed that the SMSC sheet enhanced the quality of autologous OCT by improving the integration of grafts to native cartilage and decreasing cartilage degeneration. Thus, the application of SMSC sheet can represent a therapeutic option for autologous OCT.