Insulin-like growth factor I supports differentiation of cultured osteoblast-like cells

Abstract

Rat calvaria cells grown in culture for one week had properties of osteoblasts: a high content in alkaline phosphatase and a marked cyclic AMP response to parathyroid hormone (PTH). In short-term experiments, insulin-like growth factor I (IGFI) stimulated the incorporation of ( 14C]glucose into glycogen. When IGF I was present in the medium during 6 days the cell number increased slightly and there was a substantial, disproportionate rise in alkaline phosphatase activity of the cultures. Thus, IGFI stimulates growth, and in addition, and in contrast to other growth factors, mainly enhances differentiation of osteoblasts.