Formation of a SIS–Cartilage Composite Graft in Vitro and Its Use in the Repair of Articular Cartilage Defects

Porcine small intestinal submucosa (SIS) is a resorbable biomaterial that upon implantation induces tissue remodelling and so may be a suitable substratum for the formation of cartilage in vitro, which could then be used to resurface damaged joints. Chondrocytes were isolated from the deep portion of articular cartilage and seeded onto SIS. They formed cartilaginous tissue that contained large proteoglycans and type II collagen. The glycosaminoglycan content of 8 week SIS–cartilaginous tissue composites was 78.9 ± 0.1% that of deep articular cartilage. The SIS–cartilaginous tissue composites were implanted into full-thickness articular cartilage defects. After 4 weeks, the composites had survived and retained their hyaline-like appearance, although fibrovascular and fibrocartilaginous tissue was also present. Defects receiving SIS alone contained predominantly fibrovascular tissue, whereas ungrafted defects were filled with fibrocartilage. SIS–cartilaginous tissue–resurfaced defects scored significantly better than SIS-filled defects, but were no different from the unfilled defects. However, the repair tissue in the composite-filled defects scored significantly higher than that in the unfilled defects. This pilot study suggests that SIS–cartilaginous tissue grafts may be useful for joint resurfacing. Further studies are required to optimize graft fixation and determine the long-term survival of the SIS–cartilaginous tissue grafts.