Architectural remodeling in deep frozen meniscal allografts after total meniscectomy

This study assesses the biological characteristics of cell repopulation and matrix remodeling in deep frozen meniscal allografts after total meniscectomy and allograft transplantation. Thirty-two mature New Zealand White rabbits were operated on, and the allografts were assessed at 12 and 26 weeks postsurgery. Before transplantation, fresh medial menisci were placed into liquid nitrogen to kill all intrinsic cells. Frozen meniscal allografts showed collagen remodeling coincident with revascularization and cellular repopulation. Biochemical characterization showed active collagen remodeling of the allografts at 12 and 26 weeks. In situ hybridization showed that expression of types I and III procollagen mRNAs were increased at 12 weeks, especially near the region of the synovial capsule. At 26 weeks after transplantation, the pattern of collagen-type expression progressed toward normal; that is, type I procollagen mRNA expression was prominent, whereas only a small amount of type III procollagen mRNA was observed. These data indicate the adaptation of the repopulating cells from the host to the frozen allograft at 26 weeks after transplantation.