Polymerized-Type I Collagen Induces a High Quality Cartilage Repair in a Rat Model of Osteoarthritis

Background: Osteoarthritis (OA) is a chronic, degenerative and inflammatory disease. It is characterized by progressive deterioration of articular cartilage. It is the most common disabling rheumatic pathology in adults older than 45 years, and there is no specific treatment. Objectives: Based on the rationale that in vitro polymerized-type I collagen induces chondrocytes proliferation, up-regulates the cartilage extracellular matrix proteins and down-regulates proinflammatory cytokines, we decided to evaluate its effect on cartilage repair in a rat model of OA. Methods: Thirty Wistar male rats with partial meniscectomy were subjected to daily high impact exercise during 3 weeks. Rats were randomly allocated into 5 groups a) training control, b)sham/operated control, c) toxicity control, d) OA treated with 4 intraarticular (IA) injections of placebo, and e) OA treated with 4 IA injections of polymerized-type I collagen. Weight, temperature and thickness of the knee were measured. Histological and radiological analysis was also performed. Type I and II collagen as well as, MMP13 expression was determined by immunofluorescence. Results: Clinimorphometric analysis showed a higher temperature and thickness of the knee in OA/placebo vs. OA/polymerized-type I collagen treated rats. Radiological and histological analysis demonstrated that polymerized-type I collagen but not placebo preserved joint cavity structure and proteoglycans content and induced an increase of 2 to 4 fold type II collagenexpressing chondrocytes whereas it inhibited type I collagen and MMP13 producing chondrocytes. Conclusion: The results suggest that polymerized-type I collagen is safe and effective chondroprotective biodrug with disease modifying effects. It induces high quality cartilage repair.