Evaluation of biodegradable polyesters modified by type II collagen and Arg-Gly-Asp as tissue engineering scaffolding materials for cartilage regeneration

Synthetic biodegradable polyesters poly(L-lactide) (PLLA) and poly(D,L-lactide-coglycolide) (PLGA) (50:50) modified by porcine type II collagen and an Arg-Gly-Asp (RGD)-containing protein were evaluated as scaffolds for cartilage regeneration in this study. Cytocompatibility of the polymer films was tested using immortalized chondrocytes. Neocartilage formation in vitro on cell-seeded scaffolds was further examined using primary porcine chondrocytes. The inflammatory response of the scaffolds was evaluated subcutaneously in rats. A pilot animal study was conducted, in which rabbit allogeneic chondrocyte-seeded scaffolds were implanted to repair the defected rabbit knee cartilage. The results demonstrated that PLGA as well as its blends with PLLA had better cell growth than pure PLLA, and that type II collagen enhanced, but RGD inhibited cell proliferation. Scaffolds made of blended PLLA/PLGA had larger dynamic compressive modulus compared to scaffolds made of PLLA or PLGA single polymer. Chondrocyte-seeded scaffolds modified by type II collagen without RGD had the greater number of cells as well as higher glycosaminoglycan (GAG) and collagen contents compared to scaffolds without type II collagen modification or scaffolds further modified with RDG. Type II collagen modification prevented infiltration by host tissue and capsule formation. Unmodified PLLA and PLLA/PLGA constructs demonstrated persisting inflammatory response after 6 months, while all type II collagen-modified PLLA/PLGA constructs showed complete repair and no inflammation. Partial or full repair was observed after 2 months of postimplantation in type II collagen-modified PLLA/PLGA constructs, with equal cellularity and 75-80% matrix contents of a normal rabbit articular cartilage. It was concluded that PLLA/PLGA blended scaffolds modified by type II collagen were a potential tissue engineering scaffold for cartilage regeneration.