LOCALIZATION OF BONE MORPHOGENETIC PROTEIN-INDUCED BONE AND CARTILAGEFORMATION ON A NEW CARRIER - FIBROUS COLLAGEN MEMBRANE

A fibrous collagen membrane (FCM) made of crosslinked reconstituted co llagen fibers was applied as a carrier of BMP. The effectiveness of FC M as a BMP carrier was compared with conventionally used insoluble bon e matrix (IBM). Partially purified BMP was obtained from a guanidine H Cl extract of bovine bone after a three-step chromatographic procedure . The BMP fraction was combined with FCM or IBM and implanted subcutan eously in the back of rats. Bone and cartilage formation were determin ed by radiographic, histologic, and biochemical analyses after removal at 1, 2, 3 and 4 weeks. After 2 weeks, bone and cartilage formation w ere evident histologically in IBM-BMP and FCM-BMP. In IBM-BMP, cartila ge was formed in the area of presumptive bone. On the other hand, in F CM-BMP, cartilage formation occurred in the space between the fibers o f fiber-bundles, while on the surface of the fibers bone formation sta rted independently. Biochemically, the most noteworthy difference betw een FCM-BMP and IBM-BMP was the marked increase in type II collagen co ntent in FCM-BMP, which contrasted with its decrease in IBM-BMP at 3 w eeks. This study demonstrated that FCM definitely functioned as a BMP carrier that led to bone and cartilage formation at distinct sites. Th erefore, we conclude that BMP could induce differentiation of immature cells preferentially into either osteogenic cells or chondrocytes dep ending upon the nature of the carrier which provides the environment f or cell differentiation.