Introduction: Current cartilage repair procedures using autologous chondrocytes rely on a variety of carriers for implantation. Collagen types I and II are frequently used and valuable properties of both were shown earlier in vitro, although a preference for either was not demonstrated. Recently, however, fibrillar collagens were shown to promote cartilage degradation. The goal of this study was to evaluate the effects of collagen type I and type II coating on chondrogenic properties of in vitro cultured human chondrocytes, and to investigate if collagen-mediated cartilage degradation occurs.
Methods: Human chondrocytes of eight healthy cartilage donors were isolated, expanded, and cultured on culture well inserts coated with either collagen type I, type II, or no coating (control). After 28 days of redifferentiation culture, safranin O and immunohistochemical staining for collagen types I, II, X, and Runx2/Cbfa1 were performed and glycosaminoglycan (GAG) and DNA content and release were examined. Further, expression of collagen type I, type II, type X, MMP13, Runx2/Cbfa1, DDR2, α2 and β1 integrin were examined by reverse transcriptase-polymerase chain reaction.
Results: The matrix, created by chondrocytes grown on collagen type I- and II-coated membranes, resembled cartilage more than when grown on noncoated membranes as reflected by histological scoring. Immunohistochemical staining did not differ between the conditions. GAG content as well as GAG/DNA were higher for collagen type II-coated cartilage constructs than control. GAG release was also higher on collagen type I- and II-coated constructs. Expression of collagen type X was higher of chondrocytes grown on collagen type II compared to controls, but no collagen X protein could be demonstrated by immunohistochemistry. No effects of collagen coating on DDR2 nor MMP-13 gene expression were found. No differences were observed between collagen types I and II.
Conclusion: Chondrocyte culture on collagen type I or II promotes more active matrix production and turnover. No significant differences between collagen types I and II were observed, nor were hypertrophic changes more evident in either condition. The use of collagen type I or II coating for in vitro models, thus, seems a sound basis for in vivo repair procedures.