Regeneration of Whole Meniscus Using Meniscal Cells and Polymer Scaffolds in a Rabbit Total Meniscectomy Model

The current treatments of meniscal lesion in knee joint are not perfect to prevent adverse effects of meniscus injury. Tissue engineering of meniscus using meniscal cells and polymer scaffolds could be an alternative option to treat meniscus injury. This study reports on the regeneration of whole medial meniscus in a rabbit total meniscectomy model using the tissue engineering technique. Biodegradable scaffolds in a meniscal shape were fabricated from polyglycolic acid (PGA) fiber meshes that were mechanically reinforced by bonding PGA fibers at cross points with 75:25 poly(lactic-co-glycolic acid). The compressive modulus of the bonded PGA scaffold was 28-fold higher than that of nonbonded scaffold. Allogeneic meniscal cells were isolated from rabbit meniscus biopsy and cultured in vitro. The expanded meniscal cells were seeded onto the polymer scaffolds, cultured in vitro for 1 week, and transplanted to rabbit knee joints from which medial menisci were removed. Ten or 36 weeks after transplantation, the implants formed neomenisci with the original scaffold shape maintained approximately. Hematoxylin and eosin staining of the sections of the neomenisci at 6 and 10 weeks revealed the regeneration of fibrocartilage. Safranin-O staining showed that abundant proteoglycan was present in the neomenisci at 10 weeks. Masson's trichrome staining indicated the presence of collagen. Immunohistochemical analysis showed that the presence of type I and II collagen in neomenisci at 10 weeks was similar to that of normal meniscal tissue. Biochemical and biomechanical analyses of the tissue-engineered menisci at 36 weeks were performed to determine the quality of the tissue-engineered menisci. Tissue-engineered meniscus showed differences in collagen content and aggregate modulus in comparison with native meniscus. This study demonstrates, for the first time, the feasibility of regenerating whole meniscal cartilage in a rabbit total meniscectomy model using the tissue engineering method.