Meniscal tissue regeneration using a collagenous biomaterial derived from porcine small intestine submucosa

Purpose: The present investigation is a preliminary study designed to evalu ate the use of a collagen-based biomaterial, chemically unaltered porcine s mall intestine submucosa (SIS), as a scaffold for meniscal tissue regenerat ion. Type of Study: Basic research. Methods: Surgical defects were created in the lateral menisci of 12 mature New Zealand white rabbits. The defects were repaired with a similarly shaped and sized wedge of a new collagenous biomaterial (SIS) and sutured in place. The opposite knees served as contro ls by creating a defect in the lateral meniscus without filling with SIS gr aft. Full cage activity was allowed until the animals were killed at 4, 12, and 24 weeks. Results: At 4 weeks, the graft material retained its physica l position and grossly appeared soft and translucent. Histologically, cellu lar elements had infiltrated between the laminates of the graft. At 12 week s, the graft grossly appeared more solid and opaque. Histologically, the ho st meniscal fibrochondrocytes were seen streaming into the peripheral margi n of the graft. Early repopulation of the graft with apparently differentia ted meniscal tissue was observed. At 24 weeks, the meniscus defect was gros sly healed across and looked virtually normal: the normal meniscal shape, c ontour, consistency, and color had been replicated. Histologically, the hea ling tissue showed infiltration of what appeared to be meniscal fibrochondr ocytes and connective tissue resembling the host meniscal tissue. The graft was nearly totally replaced by host tissue. Conclusions: This pilot animal study demonstrates that the multilaminated collagenous graft is conducive for cellular repopulation with host meniscal elements, and, by 24 weeks, is capable of supporting complete healing of a large meniscal defect.