Localization of carboxy-terminal type II procollagen peptide (pCOL-II-C) and type II collagen in the repair tissue of full-thickness articular cartilage defect.

It is well established that a full-thickness articular cartilage defect is repaired with a fibrocartilaginous tissue of which cells are derived from undifferentiated mesenchymal stem cells in the bone marrow. To characterize the repair tissue immunohistochemically, full-thickness defects were created in rabbit knee joints, and the repair tissues immunostained at 3, 6, and 12 weeks after surgery. Well characterized polyclonal antibody against carboxyterminal type II procollagen peptide (pCOL-II-C) and monoclonal antibody against type II collagen were used to evaluate the repair tissue with regard to the metabolism of type II collagen. Immunohistochemistry revealed that pCOL-II-C was localized in or around most of the repair cells obtained at 3 and 6 weeks after surgery, while type II collagen distributed mainly in the pericellular matrix of metaplastic round-shaped repair cells. The results suggest that the repair cells taken at the early stage of the repair process of the defect could originally have more activity of type II collagen synthesis.