Photo-cross-linked methacrylated polysaccharide solution blends with high chondrocyte viability, minimal swelling, and moduli similar to load bearing soft tissues

Photo-cross-linked hydrogels produced from solution blends of methacrylated glycol chitosan (MGC), hyaluronic acid (MHA) and chondroitin sulfate (MCS) were examined for their potential use as load bearing soft tissue (LBST) repair constructs. The effect of the degree of prepolymer methacrylation (X, Y or Z; based on a repeating dimer unit) on the final hydrogel properties was investigated using solutions of 6% w/v for MGC (6%MGC-X, where X = 12%, 26% or 58%) and MHA (6%MHA-Y, where Y = 14%, 42% or 96%) and 20% w/v for MCS (20%MCS-Z, where Z = 16%, 26% or 45%). The goal was to adjust the cross-link density to produce hydrogels with moduli greater than 100 kPa to be suitable for load bearing applications while also minimizing swelling after cross-linking (±10% change in volume), and maintaining high viability and high metabolic activity of the encapsulated chondrocytes. These objectives were achieved by cross-linking solution blends of either the 6%MGC-12 or 6%MHA-42 with the 20%MCS-45 prepolymer at 50% mass fraction (5050 MGC12MCS45 and 5050 MHA42MCS45). Chondrocyte viability within blended hydrogels were greater than 70% after 24 h of culture, but metabolic activity was highest in the MHA based hydrogels (single component and blended) over a 35 day culture period. Overall, the high initial modulus, low swelling and enhanced metabolic activity of the encapsulated chondrocytes within the 5050 MHA42MCS45 hydrogels suggests they may be suitable for use in a reparative load bearing soft tissue construct.