Alphaª²SMA expression and chondrocyte dedifferentiation

    JI Yuª²Hua, ZENG Yaoª²Ying, ZHAO Jingª²Xian

    Institute of Tissue Transplantation & Immunology, Jinan Univerª²sity, Guangzhou 510632, China

    ¡¾Abstract¡¿ AIM: To investigate the relationship between cytoskeleton ¦Áª²SMA (alphaª²smooth muscle actin) expression and dedifferentiation of chondrocyte. METHODS: Rat costochondral growth plate chondrocytes (RGCs) were isolated and cultured. Growth kinetics of RGCs during serial passage was analyzed, and ¦Áª²SMA, collagen type¢ò and GAG expressions of primary to 5th passage RGCs were detected by immunocytochemistry, Western Blot and Alcian blue staining, respectively. RESULTS: With increasing passage number, the index of duplication/day of RGCs rose during the first 3 passages and decreased afterwards. Primary RGCs expressed collagen type ¢ò and were stained strongly for Alcian blue, and very few RGCs were positive for ¦Áª²SMA. The percentage of collagen type ¢ò and Alcian blue positive stained RGCs decreased with increasing passage number. Only the roundish cells of the 5th passage retained positive for collagen type¢ò, and Alcian blue staining of 3rd passage was negative, while ¦Áª²SMA positive stained RGCs increased gradually. Western Blot results were consistent with immunocytochemical outcomes. CONCLUSION: As the degrees of RGCs dedifferentiation rise, ¦Áª²SMA expression increases gradually. The expression pattern of ¦Áª²SMA suggests that it might be an important factor in inducing chondrocyte dedifferentiation. ......