Articular cartilage regeneration using cell sheet technology.

Cartilage damage is typically treated by chondrocyte transplantation, mosaicplasty, or microfracture. Recent advances in tissue engineering have prompted research on techniques to repair articular cartilage damage using a variety of transplanted cells. We studied the repair and regeneration of cartilage damage using layered chondrocyte sheets prepared in a temperature-responsive culture dish. We previously reported achieving robust tissue repair when covering only the surface layer of partial-thickness defects with layered chondrocyte sheets in domestic rabbits. We also reported good Safranin O staining and integration with surrounding tissue in a minipig model of full-thickness cartilaginous defects in the knee joint. We have continued our studies using human chondrocytes obtained from patients under IRB approval, and have confirmed the safety and efficacy of chondrocyte sheets, and have submitted a report to the Ministry of Health, Labour, and Welfare in Japan. In 2011, the Ministry gave us approval to perform a clinical study of joint repair using cell sheets. We have just started implanting cell sheets in patients at Tokai University Hospital.