Enzymatically-crosslinked injectable hydrogels based on biomimetic dextran–hyaluronic acid conjugates for cartilage tissue engineering

Polysaccharide hybrids consisting of hyaluronic acid (HA) grafted with a dextran–tyramine conjugate (Dex–TA) were synthesized and investigated as injectable biomimetic hydrogels for cartilage tissue engineering. The design of these hybrids (denoted as HA-g-Dex–TA) is based on the molecular structure of proteoglycans present in the extracellular matrix of native cartilage. Hydrogels of HA-g-Dex–TA were rapidly formed within 2 min via enzymatic crosslinking of the tyramine residues in the presence of horseradish peroxidase and hydrogen peroxide. The gelation time, equilibrium swelling and storage modulus could be adjusted by varying the degree of substitution of tyramine residues and polymer concentration. Bovine chondrocytes incorporated in the HA-g-Dex–TA hydrogels remained viable, as shown by the Live–dead assay. Moreover, enhanced chondrocyte proliferation and matrix production were observed in the HA-g-Dex–TA hydrogels compared to Dex–TA hydrogels. These results suggest that HA-g-Dex–TA hydrogels have a high potential as injectable scaffolds for cartilage tissue engineering.