Corticosteroid-dependent differentiation of human marrow preadipocytes in vitro

A unique population of human bone marrow-derived, adherent fibroblastlike cells differentiates to adipocyte morphology when grown in vitro in the presence of horse serum and hydrocortisone sodium hemisuccinate. Over the initial 8-weeks growth at 37 degrees C, 7% CO2, these cells accumulate Oil Red O-positive lipid and form colonies of over 100 cells, which persist in confluent cultures for over 30 weeks. Similar to cultures derived from mouse marrow, corticosteroid-induced adipocyte differentiation is associated with long-term granulopoiesis. Human marrow preadipocytes, as well as human, mouse and rat embryo fibroblast cell lines, failed to differentiate to adipocyte morphology in the presence of insulin. In contrast, the 3T3-L1 insulin-dependent preadipocyte cell line was not induced to differentiate in the presence of hydrocortisone. These studies demonstrate that human marrow preadipocytes are dependent upon corticosteroid for differentiation in vitro.