Human placenta-derived mesenchymal stem cells with silk fibroin biomaterial in the repair of articular cartilage defects

Cartilage tissue engineering requires a porous biodegradable scaffold and nonimmunogenic cells with chondrogenic potential. In this study, the ability of the placenta-derived mesenchymal stem cells (PMSCs) to grow on silk fibroin (SF) biomaterial was determined, and the potential of a SF biomaterial serving as a delivery vehicle for human PMSCs in a rabbit articular cartilage defects model was evaluated. Human PMSCs were maintained in vitro in an allogeneic mixed lymphocyte reactions (MLR) system to investigate the suppressive effects on T cell proliferation. A total of 12 healthy adult New Zealand rabbits were implanted with a PMSC/SF biomaterial complex after articular cartilage defects of the femoral condyle in the knee were established. The repair of the articular cartilage defects was observed after 4 weeks, 8 weeks, and 12 weeks. Results from the MLR indicated that human PMSCs inhibited rabbit T cell responses. Knee damage was repaired by the newly formed hyaline cartilage, and within 12 weeks there was neither degeneration nor infiltration with lymphocytes or leukocytes, and no silk fibroin biomaterial residue was detected. In conclusion, the silk fibroin biomaterial can be applied as a new scaffold for cartilage tissue engineering, and implantation of human PMSCs on the cartilage can enhance repair of articular cartilage defects in a rabbit model.