The Effect of Growth Differentiation Factor-5, 6, 7 in Chondrogenic Cell Differentiation of ATDC-5

The proteins known as growth differentiation factors (GDFs) are members of the BMP family; GDF-5, -6, and -7 play important roles in skeletogenesis, especially with regard to chondrogenesis. The functional differences among these GDFs in chondrogenesis and chondrocyte cell differentiation remains unclear. Here, we attempt to assay cell proliferation, the production of chondrogenic matrices indicated by alcian blue intensity, and the profile of a chondrogenic cell differentiation marker gene in a cell culture of the chondrogenic cell line ATDC5 with or without recombinant mouse GDF-5, -6, and -7. After 24h culture, the ATDC5 cell number was significantly decreased in the exogenous presence of each GDF compared with a control culture absent all GDFs. On the other hand, alcian blue staining of cell cultures after 2w culture showed significantly increased intensity compared with that of the control. The expression levels of the chondrogenic cell differentiation marker genes Sox9 and aggrecan were increased after 24h and 48h culture by all GDFs, but were significantly increased in the presence of GDF-5 compared with the presence of GDF-6 or -7. These findings suggest that GDF-5, -6, and -7 could all promote chondrogenic cell differentiation of ATDC5, but GDF-5 may induce chondrogenic genes more potently than GDF-6 and -7 do.