The aging process and traumatic injuries frequently cause damage to articular cartilage that, if left untreated, can result in arthritic lesions of the joint surface with concomitant loss of function. With current treatment modalities, the resultant repair, typically consisting of fibrocartilage, often degenerates over time to arthritis. The aim of our research is to utilize tissue engineering techniques to develop a method for healing articular cartilage lesions. We successfully treated rabbit cartilage lesions with an implant consisting of rabbit chondrocytes in a collagen matrix carrier. We harvest and grow the rabbit cells in culture and seed them into a collagen bilayer, designed to prevent ingrowth of fibrous tissues into the lesion while acting as a scaffold for transplanted chondrocytes. The engineered collagen/chondrocyte construct is then implanted in articular defects in the rabbit knee.

Extensive mechanical, histological, and biochemical evaluations show that the regenerated cartilage has properties nearly identical to those of the normal cartilage. Furthermore, this neocartilage showed no sign of arthritic deterioration 6 mo after implantation. We are investigating the use of growth factors to enhance the repair induced by the cell transplants and extending our studies to large animal models to replicate the clinical situation.