Articular cartilage repair with autologous bone marrow mesenchymal cells.

Articular cartilage defects that do not repair spontaneously induce osteoarthritic changes in joints over a long period of observation. In this study, we examined the usefulness of transplanting culture-expanded bone marrow mesenchymal cells into osteochondral defects of joints with cartilage defects. First, we performed experiments on rabbits and up on obtaining good results proceeded to perform the experiments on humans. Macroscopic and histological repair with this method was good, and good clinical results were obtained although there was no significant difference with the control group. Recent reports have indicated that this procedure is comparable to autologous chondrocyte implantation, and concluded that it was a good procedure because it required one step less than that required by surgery, reduced costs for patients, and minimized donor site morbidity. Although some reports have previously shown that progenitor cells formed a tumor when implanted into immune-deficient mice after long term in vitro culture, the safety of the cell transplantation was confirmed by our clinical experience. Thus, this procedure is useful, effective, and safe, but the repaired tissues were not always hyaline cartilage. To obtain better repair with this procedure, treatment approaches using some growth factors during in vitro culture or gene transfection are being explored.