Analysis of Collagen Type II and X in Ageing and Osteoarthritic Articular Cartilage

Abstract

Objective: Collagens identified in articular cartilage include the cartilage specific collagen types II, IX, X and XI as well as the more universally distributed types III, V, VI, XII and XIV. Type II collagen is the predominant and characteristic collagen of the articular cartilage, composed of a triple helix of three identical α chains. The hypertrophic chondrocytes of calcified zone of articular cartilage synthesize type X collagen in addition to the type II collagen. The present study was conducted to observe the changes in the collagenase activity in osteoarthritis by detecting TCA fragment of the α chain of collagen type II. The expression of native collagen type X was also observed in the osteoarthritic articular cartilage by SDS-PAGE and western blotting. Methods: 22 osteoarthritic cartilage specimens were obtained from patients with primary osteoarthritis (46-81years) undergoing total knee replacement. 12 age-matched (41-86years) and 14 young (16-40years) non-osteoarthritic control cartilage specimens were obtained from the cadavers in the department of Anatomy and from patients undergoing lower limb amputation in Trauma center of PGIMER, Chandigarh. The cartilage specimens were processed for SDS-PAGE and western blotting. Results: Analysis of the α-chymotrypsin extracts of the articular cartilage for TCA fragment (75kDa) of collagen type II and native collagen type X (60kDa) revealed a much higher content in the osteoarthritic group. Conclusions: The features of the articular cartilage from the osteoarthritic group were markedly different from the non-osteoarthritic age-matched articular cartilage suggesting that OA is not an inevitable feature of aging.