Culture duration modulates collagen hydrolysate-induced tissue remodeling in chondrocyte-seeded agarose hydrogels

Media supplementation with collagen hydrolysate was hypothesized to increase the collagen content in engineered cartilage. By d28, hydrolysate at 0.5 mg/mL increased type II collagen content and 1 mg/mL increased mechanical properties, total collagen content, and type II collagen content over controls. By d42, however, controls possessed the highest GAG content and compressive Young's modulus. Real-time PCR found that 1 mg/mL increased type II collagen gene expression in d0 constructs, but increased MMP expression with no effect on type II collagen on d28. A 10 mg/mL concentration produced the lowest tissue properties, the lowest type II collagen gene expression on d0, and the highest MMP gene expression on d28. These results indicate that the duration of culture modulates the response of chondrocytes to collagen hydrolysate in 3D culture, transforming the response from positive to negative. Therefore, collagen hydrolysate as a media supplement is not a viable long-term method to improve the collagen content of engineered cartilage tissue.