The effect of cryoprotectant vehicle solution on cartilage cell viability following vitrification

Osteochondral allografts are often used to repair large articular cartilage defects to prevent or delay the onset of osteoarthritis. This approach is limited by the timely acquisition and use of allograft tissue since standard hypothermic protocols allow for a maximum storage of 4 weeks. Vitrification is a proven technique for the long-term preservation of cells and tissues, but requires careful determination of parameters to be successful, particularly for articular cartilage. One parameter that is infrequently considered is the choice of cryoprotectant vehicle solution. The aim of this study was to evaluate the impact of a subset of vehicle solutions on an established vitrification protocol for articular cartilage. These solutions were phosphate-buffered saline (PBS), Dulbecco's Modified Eagle's Medium: Nutrient Mixture F-12 (DMEM), X-VIVO, and Unisol-CV (UCV). Both the solution pH at various points throughout vitrification and the cell viability of porcine articular cartilage slices following vitrification were measured. Using randomized block ANOVA, it was found that the normalized cell viability of articular cartilage vitrified in UCV was significantly greater than that of PBS (p < 0.05) and may be greater than those of DMEM and X-VIVO (p < 0.1). There was no correlation between pH parameters and cell viability, although significant differences between calculated pH parameters were identified. These results provide information to guide the design of effective vitrification protocols for articular cartilage.