The Radiated Deep-frozen Xenogenic Meniscal Tissue Regenerated the Total Meniscus with Chondroprotection.

Meniscal allograft transplantation yields good and excellent results but is limited by donor availability. The purpose of the study was to evaluate the effectiveness of radiated deep-frozen xenogenic meniscal tissue (RDF-X) as an alternative graft choice in meniscal transplantation. The xenogenic meniscal tissues were harvested from the inner 1/3 part of the porcine meniscus and then irradiated and deeply frozen. The medial menisci of rabbits were replaced by the RDF-X. Meniscal allograft transplantation, meniscectomy and sham operation served as controls. Only a particular kind of rabbit-anti-pig antibody (molecular ranging 60-80 kD) was detected in the blood serum at week 2. The menisci of the group RDF-X grossly resembled the native tissue and the allograft meniscus with fibrocartilage regeneration at postoperative 1 year. Cell incorporation and the extracellular matrix were mostly observed at the surface and the inner 1/3 part of the newly regenerated RDF-X, which was different from the allograft. The biomechanical properties of the group RDF-X were also approximate to those of the native meniscus except for the compressive creep. In addition, chondroprotection was achieved after the RDF-X transplantation although the joint degeneration was not completely prevented. To conclude, the RDF-X could be a promising alternative for meniscal transplantation with similar tissue regeneration capacity to allograft transplantation and superior chondroprotection. The potential minor immunological rejection should be further studied before its clinical application.

Meniscus transplantation using treated xenogeneic meniscal tissue: viability and chondroprotection study in rabbits.

PURPOSE: This was a preliminary study performed in vivo to evaluate the viability and the chondroprotective effects of irradiated deep-frozen xenogeneic meniscal tissue as a novel substitute for meniscus transplantation. METHODS: Medial meniscectomies were performed on the right knees of 48 New Zealand white rabbits. The inner one-third of pig meniscus was harvested and then irradiated and deeply frozen. The treated xenogeneic meniscal tissues were then transplanted to 24 right knees (Xeno group), whereas 24 other knees received meniscus allograft transplantations (Allo group). The left knees of the Xeno group and Allo group received meniscectomies (Meni group) and sham operations (Sham group), respectively. The rabbits were killed at weeks 6, 12, and 24 postoperatively. The newly formed structure of the implanted tissue and cartilage of the medial compartment of each group was assessed by gross and semiquantitative histologic analysis. RESULTS: After 24 weeks, the implanted xenogeneic meniscal tissue completely healed to the synovium and formed meniscus-like tissue. The chondrocyte-like cell infiltrated into the tissue with extracellular matrix including type II collagen and proteoglycans. The Xeno group showed significantly less cartilage degeneration than that of the Meni group in the medial tibial plateau at week 24 (P < .05). No significant difference was found between the Xeno group and the Allo group except for the meniscus-covered regions at week 24. From week 12 to week 24, almost no advanced cartilage degeneration was found in weight-bearing regions of the medial tibial plateau of the Xeno group. CONCLUSIONS: The treated xenogeneic meniscal tissue healed to the synovium with tissue regeneration and slowed down articular cartilage degeneration in the short-term. The chondroprotection of xenograft transplantation was similar to that of allograft transplantation. CLINICAL RELEVANCE: The treated xenogeneic meniscal tissue showed the potential for viability and slowed cartilage degeneration, but more studies are required for application in humans in the future.