Comparison of High Cryoprotectant Concentrations for Cryopreservation of Porcine Articular Cartilage

Abstract

Large, untreated articular cartilage (AC) defects degenerate into osteoarthritis, and successful cryopreservation of AC may improve treatment outcomes. This study compared three cryoprotectant solutions (6 M dimethyl sulfoxide, 5 M propylene glycol, and a combination solution of 3.1 M dimethyl sulfoxide, 2.2 M propylene glycol, and 3.1 M formamide in phosphate-buffered saline) using a rapid-cooling protocol on intact, 10-mm-diameter, porcine osteochondral dowels. Fresh controls, toxicity controls, and experimental samples were examined using membrane integrity stains for intact chondrocyte recovery. The results of this study demonstrated that after rapid cooling and warming, the 6 M dimethyl sulfoxide (33 ± 2%) and 5 M propylene glycol (24 ± 2%) solutions had significantly higher recovery of intact cells than the combination solution (10 ± 2%). The chondrocytes in the superficial layer were the most significantly damaged in the toxicity controls, but after rapid cooling, the middle layer in all solutions demonstrated significantly higher recovery of intact cells than the superficial layer (likely because of toxicity) and the deep layer (likely because of inadequate cryoprotectant penetration). High concentrations of cryoprotectants with a rapid-cooling rate can cryopreserve intact AC with moderate recovery of intact cells.