Principles of preservation of soft tissue allografts

Preserved soft tissues serve as allograft replacements for damaged ligaments and menisci in orthopedic surgery. Currently, the most popular method for preserving or storing soft tissue allografts is freezing. During freezing, cryopreservation is used to preserve cell viability in the grafts, with the goal of transplantation of living native cells in a transplanted allograft. Cell cryopreservation efforts have met with mixed success. Cellular viability in cryopreserved soft tissues has not been high in terms of the percentage of cells originally in the grafts and studies suggest, through comparison of donor and recipient (host) DNA, that all donor cells in the transplanted graft are replaced by host cells within a few months. Nonetheless, based on several clinical studies, cryopreserved soft tissues seem to function reasonably well in many circumstances as replacements for ligaments and menisci. Further research is necessary to achieve the goal of cellular transplantation within the grafts, but the current method of storing and preserving soft tissue allografts seems to provide satisfactory replacement tissues in many cases.