Vitrification of Intact Porcine Femoral Condyle Allografts Using an Optimized Approach

Successful preservation of articular cartilage will increase the availability of osteochondral allografts to treat articular cartilage defects. We compared the effects of 2 methods for storing cartilage tissues using 10-mm diameter osteochondral dowels or femoral condyles at -196°C: (a) storage with a surrounding vitrification solution versus (b) storage without a surrounding vitrification solution. We investigated the effects of 2 additives (chondroitin sulfate and ascorbic acid) for vitrification of articular cartilage.

Healthy porcine stifle joints (n = 11) from sexually mature pigs were collected from a slaughterhouse within 6 hours after slaughtering. Dimethyl sulfoxide, ethylene glycol, and propylene glycol were permeated into porcine articular cartilage using an optimized 7-hour 3-step cryoprotectant permeation protocol. Chondrocyte viability was assessed by a cell membrane integrity stain and chondrocyte metabolic function was assessed by alamarBlue assay. Femoral condyles after vitrification were assessed by gross morphology for cartilage fractures.

There were no differences in the chondrocyte viability (~70%) of 10-mm osteochondral dowels after vitrification with or without the surrounding vitrification solution. Chondrocyte viability in porcine femoral condyles was significantly higher after vitrification without the surrounding vitrification solution (~70%) compared to those with the surrounding vitrification solution (8% to 36%). Moreover, articular cartilage fractures were not seen in femoral condyles vitrified without surrounding vitrification solution compared to fractures seen in condyles with surrounding vitrification solution.

Vitrification of femoral condyle allografts can be achieved by our optimized approach. Removing the surrounding vitrification solution is advantageous for vitrification outcomes of large size osteochondral allografts.