Osteochondral allograft preservation in a serum-free chemically-defined media
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Articular cartilage has a very limited capacity as compared to other biological tissues to repair and regenerate because of its avascular nature. Chronic degradation of articular cartilage may result in osteoarthritis, the most common debilitating disease worldwide. In order to alleviate severe pain symptoms and dysfunction associated with osteoarthritis, treatment strategies to replace rather than repair the tissue have been developed. Osteochondral allografts (OCAs) allow the transplantation of whole cartilage tissue into a defect with viable cells, or chondrocytes that will maintain the cartilage matrix. Fresh OCAs have demonstrated greater than 75% clinical success in the treatment of articular cartilage lesions. Currently allografts are stored at 4°C and used within 28 days, however, FDA-mandated disease testing requires 14 days of screening which decreases the effective window for implantation to 14 days. The purpose of this study was to evaluate OCAs stored up to 56 days in a Control (DMEM supplemented with ITS, Sodium Pyruvate, L-ascorbic acid, and MEM Non-essential amino acids) and Test (DMEM) supplemented ITS+, Sodium Pyruvate, L-ascorbic acid, MEM Non-Essential amino acids, dexamethasone, boron, and TGF-β3) media preparation at 4°C and 37°C. Media was changed and collected every 7 days. At Days 0, 28, and 56, full thickness cartilage was evaluated for cell viability, GAG and HP content, and histologic evaluation. Media was collected at Days 7, 14, 21, 28, 35, 42, 49, and 56 for GAG content of the media, a measure of GAG release from tissue. Media collected on Days 7, 28, and 56 was also evaluated for NO, PGE2, MMP, and cytokine content. Cell viability as well as tissue GAG and HP content were maintained at Day 0 levels up to Day 56 in the 37°C Control media. GAG release of tissues at 37°C indicated active metabolism in the tissue. The profile of cytokines released during storage by OCAs stored in the 37°C Control media may be a preliminary step towards a screening protocol for testing OCA viability during storage. Our work showed that storage in a serum-free chemically-defined media at 37°C can maintain OCAs \ better than the current tissue banking protocol for storage.