Transplantation of cartilagenous tissue generated in vitro into articular joint defects

The purpose of this pilot study was to determine whether isolated rabbit chondrocytes will form cartilagenous tissue in culture and whether this tissue can be used as a cartilage transplant in order to resurface damaged joints. Chondrocytes were isolated from rabbit articular cartilage, plated as a monolayer on Millicell-CMR filters and maintained in cell culture. The cells formed cartilagenous tissue that could be removed from the filter support by two weeks in culture. The chondrocytes synthesize type II collagen indicating that they maintained their phenotype under these conditions. For the transplant studies, two types of articular surface defects, either full thickness into subchondral bone or intra-chondral, were created in rabbits. The cartilagenous tissue was placed in the defect either without fixation or with the topical application of an adhesive agent (Cell-Tak or Nexaband Avian). The joints were examined within two weeks following the surgery. No transplants remained in the defects in those animals in which tissue fixation had been attempted with Cell-Tak. Those grafts fixed into the cartilage defect with Nexaband Avian remained in place but consisted of a condensed layer of acellular tissue. However, cartilagenous tissue was present and intact in five of the six animals in which the transplant had been placed, in the absence of adhesive, into a full thickness defect. In conclusion, cartilagenous tissue generated in vitro can survive transplantation but an appropriate method to fix grafts into intra-chondral defects is required.