Extracellular matrix-based cryogels for cartilage tissue engineering.

In this study, we investigated various highly porous extracellular matrix (ECM)-based cryogels for cartilage tissue engineering. For the fabrication of ECM-based cryogels, either methacrylated chondroitin sulfate (MeCS) or methacrylated hyaluronic acid (MeHA) were cross-linked along with poly (ethylene glycol) diacrylates (PEGDA) via free radical polymerization under freezing conditions. This procedure induces ice crystallization (used as a porogen) prior polymer crosslinking in which, after complete cryopolymerization, a thawing process transforms the ice crystals into a unique interconnected macroporous structure within ECM-cryogels. The developed ECM-cryogels exhibited an average macroporosity of 75% and supported the infiltration of chondrocyteds. When rabbit chondrocytes were cultured on ECM-cryogels, MeCS-based cryogels stimulated aggrecan gene expression and GAG accumulation, whereas MeHA-based cryogels stimulated type II collagen gene expression and collagen accumulation. These results demonstrate that design of ECM-based cryogels can play an important role in promoting specific ECM proteins secretion for cartilage tissue engineering.