Osteoblastlike cells in a serum-free methylcellulose medium form colonies: effects of insulin and insulinlike growth factor I.

Abstract

Osteoblastlike (OB) cells obtained from a heterogeneous primary cell population by enzymatic cell digestion of calvaria of newborn rats are grown in a serum-free viscous alpha-MEM/F-12 medium containing 0.8% methylcellulose. In contrast to cell monolayers in conventional tissue cultures OB cells proliferate into colonies of rounded-up cells to form morulalike spherical cell clusters containing up to 100 cells. These colonies, with different cell numbers, are clearly not fibroblastlike since fibroblasts from the same rats always grow as a cell monolayer. Alkaline phosphatase activity and cAMP responsivness to PTH are expressed more markedly (70% and 250% respectively) by OB cells in the descr..