Influence of the Structural Mechanics and Surface Properties of Injectable Chitosan Methacrylate-Based Hydrogels for Autologous Chondrocyte Implantation

Current strategies for autologous chondrocyte implantation explore the use of gel systems that have structural similarity to an extracellular matrix of cartilage tissue and can act as chondrocyte carriers. However, the major requirement is to address the challenge of maintaining the phenotype and bio-functionality of chondrocytes which often undergo dedifferentiation on expansion, and the appropriate mechanical properties of the matrix that can influence cell attachment and growth. Injectable gel systems are developed in this study by blending different ratios of methacrylated chitosan and polyethylene glycol diacrylate, and photocross-linking the system to attain a stable gel. We hypothesize a multiscale approach of evaluating various parameters like the physical and structural properties of the gel, its wettability and surface free energy and mechano-rheological properties along with the biological characterization (viability assay, collagen, and glycosaminoglycan estimation by immunostaining, biochemical analysis, and RT-PCR assay) of the gel in ascertaining its ideal matrix system. The study provides a correlation between the different parameters to arrive at the most optimum characteristic of an ideal gel system which is dependent not only on the elastic modulus and surface free energy properties of the matrix but also on the composition of the matrix and the phenotype and functionality of the encapsulated chondrocytes.