Activation of cartilage-derived morphogenetic protein-1 in torn rotator cuff

Localization and expression of cartilage-derived morphogenetic protein-1 in tissues of torn rotator cuff tendons were examined by in situ hybridization and immunohistochemical analysis. Histologic findings of torn rotator cuff tendons showed that active cells synthesizing the alpha-1 chain of collagen Type I messenger ribonucleic acid were localized predominantly in the torn edge and in the bursa side rather than in the joint side, and scarcely localized in a site distant from the torn edge. Cartilage-derived morphogenetic protein-1 had a similar distribution as the alpha-1 chain of collagen Type I. The current findings provide the first observational evidence that cartilage-derived morphogenetic protein-1 was activated specifically at the site of the torn rotator cuff tendon. The current findings suggest that the cells in the torn rotator cuffs are capable of synthesizing cartilage-derived morphogenetic protein-1, one of the known essential factors for tendon formation.