Potential of an injectable chitosan/starch/beta-glycerol phosphate hydrogel for sustaining normal chondrocyte function.

An injectable hydrogel for chondrocyte delivery was developed by blending chitosan and starch derived from various sources with beta-glycerol phosphate (beta-GP) in the expectation that it would retain a liquid state at room temperature and gel at raised temperatures. Rheological investigation indicated that the system consisting of chitosan derived from crab shell and corn starch at 4:1 by weight ratio (1.53%, w/v of total polymers), and 6.0% (w/v) beta-GP (C/S/GP system) exhibited the sharpest sol-gel transition at 37+/-2 degrees C. The C/S/GP hydrogel was gradually degraded by 67% within 56 days in PBS containing 0.02 mg/ml lysozyme. The presence of starch in the system increased the water absorption of the hydrogel when compared to the system without starch. SEM observation revealed to the interior structure of the C/S/GP hydrogel having interconnected pore structure (average pore size 26.4 microm) whereas the pore size of the hydrogel without starch was 19.8 microm. The hydrogel also showed an ability to maintain chondrocyte phenotype as shown by cell morphology and expression of type II collagen mRNA and protein. In vivo study revealed that the gel was formed rapidly and localized at the injection site.