Human adipose tissue endothelial cells promote preadipocyte proliferation

Adipogenesis is preceded by development of a microvascular network, and opt imal functioning of adipose tissue as an energy store and endocrine organ i s dependent on extensive vascularization. We have examined the role of endo thelial cell-derived factors that influence the proliferation of human prea dipocytes. Microvascular endothelial cells and preadipocytes were isolated from human omental and subcutaneous adipose tissue biopsies by use of a dev eloped procedure of collagenase digest, immunoselection, and differential t rypsinization. Conditioned medium from microvascular endothelial cell cultu res promoted the proliferation of preadipocytes (P<0.001) and (to a lesser extent) other cell types. No depot-specific differences in mitogenic capaci ty of microvascular endothelial cell medium or of preadipocyte response wer e observed. These results indicate that adipose tissue endothelial cells se crete soluble adipogenic factor(s).