Cryopreservation of cartilage.

We have investigated the viability and function of cells in cartilage slices after various methods of preservation, and have examined the viability of cells by measuring the incorporation of Na2(35)SO4 at different concentrations, temperatures and times of exposure to cryopreservatives. We have assessed the viability of cells when exposed to pre-freezing temperatures, and after preservation at -80 degrees C. The best survival rate was found to be with a concentration of cryopreservatives of approximately 10%, with pre-freeze exposure for four hours at 4 degrees C. In the stage cooling technique, the best initial cooling was at -30 degrees C for 30 minutes, followed by rapid cooling of the cartilage to -80 degrees C. The best survival rate for cryopreserved cartilage in 10% DMSO was, on average, 19% in intact slices and 34% when holes had been made in the slices. Proteoglycan synthesis after thawing appeared normal, and proteoglycan labelled after 48 hours in culture also showed a normal pattern.