Alginate hydrogel embedding poly(D,L-lactide-co-glycolide) porous scaffold disks for cartilage tissue engineering

Small poly(D,L-lactide-co-glycolide) scaffold disks (2 mm in diameter) with a bimodal porous structure of 237.5±34.2 μm for large pores and 9.2±3.9 μm for micropores were prepared by gas-forming and controlled-pre-cipitation methods. Chondrocyte-seeded scaffold disks were dispersed in an alginate solution containing culture media. The dispersion was transferred into a Teflon mold with a specific shape, eventually forming an alginate hydrogel (approximately 1 cm in dimension) that contains cell/disk aggregates after crosslinking using CaCl ₂. In vitro assessment of the alginate hydrogel showed significant increases in DNA and glycosaminoglycan content after 21 days, suggesting that chondrocyte still proliferated on the small scaffold disks in the alginate hydrogel despite its large dimensions. Moreover, in vivo immunohistochemical analysis of the alginate hydrogel demonstrated that chon-drocytes secreted native extracellular matrix proteins (e.g., collagen, proteoglycan). We believe that our approach of using alginate hydrogel containing cell/disk aggregates with a shape fitted to the target site could provide a versatile platform to engineer large and thick tissues and/or organs.