The Effects Of Recombinant Human Insulin-like Growth Factor (rhIGF-I) On Rat Osteoblasts In Vitro

Objective: To investigate the effects of recombinant human insulin-like growth factor (rhIGF-I) on the proliferation , apoptosis and anabolic function of cultured rat osteoblasts in vitro.Method: Rat calvaria cells were cultured in medium with or without rhIGF-I. The living cell number was assessed by MTT colorimetric assay. TNF-a was added in the medium to induce apoptosis. The cell cycle and apoptosis were analysed by flow cytometry after the cells were incubated with medium containing TNF-a or TNF-a plus rhIGF-I. Type I collagen expression was determined by immunocytochemistry and computer image analysis system. The ALP content within osteoblasts was messured by PNPP method.Results: The number of osteoblasts which were exposed to rhIGF-I(0.1 - 100ng/ml) significantly increased compared with that of cells exposed to vehicle medium. TNF-a increased the percentage of apoptic cells. rhIGF-I inhibited the inducement of TNF-a for apoptosis. The staining intensity of type I collagen in rhIGF-I-treated cells was stronger than that in vehicle-treated cells. The ALP activity in...