A novel exogenous concentration-gradient collagen scaffold augments full-thickness articular cartilage repair

Abstract

A collagen scaffold has been long used in order to enhance the regeneration of articular cartilage. In the present study, we investigate the effectiveness of a concentration-gradient (CG) collagen that is designed to recruit efficiently the mesenchymal stem cells (MSCs) to the central region of the full-thickness cartilage defects via haptotaxis. The present study used Cellmatrix (0.3% type I collagen; Nitta gelatin, Osaka, Japan) as the collagen material. We prepared 33%CG collagen gel and 50%CG collagen gel. No gradient collagen gel served as negative control. Full-thickness cartilage defects were created at the patella groove of the rabbit knee, to which the three different collagen gels were transplanted. Bromodeoxyuridine (BrdU) positive, proliferating cells were enumerated and localized, whereas the histological grading score for cartilage regeneration was counted. The expression of type I and type II collagens was evaluated by immunohistochemistry. We also confirmed that the MSCs migrate toward the collagen substrate of higher concentration in a stringently in vitro haptotactic manner. Enumeration of the BrdU-positive cells demonstrated that 33%CG collagen gel recruited a significantly larger number of proliferating cells to the central region of the cartilage defect. The histological grading score for the regenerated cartilage treated with 33%CG collagen gel was superior to the other groups. CG collagen scaffold recruits effectively the MSCs to the center of full-thickness cartilage defect and enhances regeneration of the full-thickness cartilage defect.