Optimizing Co2 Enhances Chondrocyte Viability during Cold Storage

INTRODUCTION: Successful repair of full thickness defects to articular cartilage remains a clinical and scientific challenge. The use of fresh osteochondral allografts to replace damaged articular cartilage with healthy tissues harvested from human cadavers is a viable treatment option. Allografts are stored at 4C prior to transplantation to await final culture results that can take two to three weeks to complete. Yet the presence of live and normally functioning chondrocytes in fresh osteochondral allografts has been shown to decrease remarkably within 14 days of cold storage. To maintaim sterility, allografts are stored in sealed packages prepared in ambient room air conditions that may lack sufficient CO2 with attendant changes to the pH resulting in potential cell death. There is also evidence that apoptosis plays a role in chondrocyte cell death when cartilage explants are subjected to environmental stress. This study was performed to test the hypotheses that (1) cold storage and pH changes increase chondrocyte necrosis and apoptosis, and that (2) optimizing CO2 normalizes pH and enhances chondrocyte viability when stored at 4o C.