Quantification of expression levels of cellular differentiation markers does not support a general shift in the cellular phenotype of osteoarthritic chondrocytes.

Many studies have shown increased anabolic activity in osteoarthritic cartilage and have suggested changes in the cellular phenotypes of articular chondrocytes. Most of these studies relied on non-quantitative technologies, which did not allow the estimation of the relative importance of the different differentiation phenomena. In the present study, we developed and used quantitative PCR assays for collagen types I, II(total), IIA, III, and X as marker genes indicating cellular synthetic activity (collagen type II) as well as differentiation pattern of chondrocytes (collagen types I, IIA, III, and X) and quantified these genes in normal, early degenerative, and late stage osteoarthritic cartilage in parallel.