Expansion of Human Articular Chondrocytes on Microcarriers Enhances the Production of Cartilage Specific Matrix Components

Cell based technologies for the repair of cartilage defects usually rely on the expansion of low numbers of chondrocytes isolated from biopsies of healthy cartilage. Proliferating chondrocytes are known to undergo dedifferentiation which is characterised by down-regulation of collagen type II and proteoglycan production, and by up-regulation of collagen type I synthesis. Re-expression of cartilage specific matrix components by expanded chondrocytes is therefore critical for successful cartilage repair. In this study, it is shown that the quality of matrix synthesis by expanded chondrocytes is highly dependent on the method of expansion. Expanding human articular chondrocytes (HAC) on microcarriers without subcultivation steps leads to higher matrix synthesis rates and to superior ratios of collagen type II to type I forming cells than the expansion in conventional monolayer culture.