Influence of chondrocytes of different origin on early differentiation of bone marrow mesenchymal stem cells in co-culture system

Abstract

Objective To investigate the influence of chondrocytes originating from different source on early chondrogenic differentiation of bone marrow mesenchymal stem cells (MSCs) in isolated co-culture system. Methods We applied hanging cell-culture system to culture chondrocytes of different origin (osteoarthritis chondrocyte cells, nomal chondrocyte cells, infant chondrocyte cells) and controls. These chondrocytes and MSCs of the same origin were cultured in the common medium in a separated condition, and observed by microscope at 3, 6, 9, 12 day after co-culture. Expression levels of aggrecan, collagen type Ⅱ (Col-2), cartilage-specific transcription factor (Sox-9) in MSCs of different origin were determined by Real-time PCR. Results MSCs showed obviously morphological differentiation induced by chondrocytes of different origin at 12 day after co-culture as compared with controls. Real-time PCR analysis showed that SOX9 mRNA level was stimulated by 1.7-fold, 1.6-fold and 1.2-fold (all P<0.05) and aggrecan mRNA level was increased by 2.8-fold, 2.2-fold and 1.3-fold (all P<0.05) in infant chondrocytes group, nomal chondrocytes group, osteoarthritis chondrocytes group respectively as compared with controls while COL2 mRNA level had no significant differences among the four groups. Corresponding protein signal level had obvious differences among the four groups, especially in infant chondrocytes as compared with osteoarthritis chondrocytes and nomal chondrocytes. Conclusions Isolated co-culture system may indirectly promote MSCs differentiation to chondrocytes by local micro-environment regulation. Chondrocytes of different origin have different effects on MSCs differentiation, but they could promote MSCs differentiation to chondrocytes. Key words: Chondrocytes; Cell differentiation; Coculture techniques; Mesenchymal stem cells