Fig. 3.

The effects of incorporating negatively charged chondroitin sulfate into neutral PEG hydrogels when cultured under free swelling conditions on nitric oxide production as measured by nitrite production (A), cell proliferation (B), proteoglycan synthesis (C) and total collagen content (D) for chondrocytes encapsulated in PEG-only or PEG-ChS gels. Nitrite production, cell proliferation and proteoglycan synthesis were measured for the culture period between 6 and 12 hours. Total collagen content, as measured through hydroxyproline, represents the total accumulation over the first 12 hour culture period. Each cell response is normalized to total DNA content and reported as mean ± standard deviation (n =4–5); *p <0.05, **p<0.01, ***p<0.001.