Developing insoluble type II collagen microfiber scaffolds for cartilage tissue engineering

Regenerative medicine strategies employing biomimetic scaffolds have emerged as promising approaches for cartilage repair and regeneration. Type II collagen is an attractive biomaterial for the fabrication of biomimetic scaffolds in cartilage tissue engineering. In this study, we developed a novel non-enzymatic method to purify native insoluble type II collagen fibers from articular cartilage and a new procedure to fabricate insoluble type II collagen microfiber scaffolds with microstructural features and mechanical properties comparable to those of insoluble type I collagen microfiber scaffolds. This equivalence allowed for direct comparison of their intrinsic bioactivity. We used chondrocyte redifferentiation as a tool to test the hypothesis that insoluble type II collagen microfiber scaffolds have greater potential for cartilage tissue engineering than insoluble type I collagen scaffolds. Dedifferentiated bovine chondrocytes were seeded into collagen scaffolds and cultured in chondrocyte differentiation medium under dynamic and hypoxic conditions. The molecular analysis for chondrogenic gene expression, biochemical analysis for glycosaminoglycans and DNA, and histological staining for glycosaminoglycans demonstrate that insoluble type II collagen microfiber scaffolds promote superior chondrocyte redifferentiation compared to insoluble type I collagen scaffolds. To our knowledge, this is the first study to demonstrate the fabrication of scaffolds composed entirely of insoluble type II collagen microfibers and their stronger capacity than insoluble type I collagen microfiber scaffolds in reestablishment of cartilage-specific phenotypes of dedifferentiated chondrocytes. This work highlights the feasibility and therapeutic potential of native insoluble type II collagen microfibers as a physiologically relevant biomaterial for developing next-generation biomimetic scaffolds to promote cartilage repair and regeneration.