ISOLATION OF A PREADIPOCYTE CELL-LINE FROM RAT BONE-MARROW AND DIFFERENTIATION TO ADIPOCYTES

A unique population of rat adipocyte precursor cells was derived from normal rat bone marrow The epitheloid-like preadipocytes were isolated from a mixed culture of bone marrow cells by a combination of differe ntial trypsinization, enrichment by Ficoll gradient centrifugation, an d differential seeding. This cell line, designated RBM-Ad, can be full y differentiated into multilocular adipocytes morphologically resembli ng brown adipose tissue. No changes in the differentiation pattern are observed during propagation of these cells, and they have been succes sfully carried and differentiated up to passage 49. Histological stain ing of differentiated cells with Sudan black, Sudan IV, and oil red O indicates the presence of lipids in intracellular vesicles. The nonsel ective beta-adrenergic agonist isoproterenol stimulates adenylyl cycla se activity in both preadipocytes and differentiated adipocytes. In co ntrast, BRL-37344, a beta(3)-adrenergic receptor-specific agonist, sti mulates adenylyl cyclase activity and glycerol release in differentiat ed adipocytes, but not preadipocytes. In addition, differentiated adip ocytes contain messenger RNA encoding the brown adipose-specific prote in, thermogenin. Thus, this rat preadipocyte cell line can be differen tiated into adipocytes that histologically and functionally resemble b rown adipose tissue.