Characterization of a primary brown adipocyte culture system derived from human fetal interscapular fat

Brown fat has gained widespread attention as a potential therapeutic target to treat obesity and associated metabolic disorders. Indeed, the anti-obesity potential of multiple targets to stimulate both brown adipocyte differentiation and recruitment have been verified in rodent models. However, their therapeutic potential in humans is unknown due to the lack of a human primary brown adipocyte cell culture system. Likewise, the lack of a wellcharacterized human model has limited the discovery of novel targets for the activation of human brown fat. To address this current need, we aimed to identify and describe the first primary brown adipocyte cell culture system from human fetal interscapular brown adipose tissue. Pre-adipocytes isolated from non-viable human fetal interscapular tissue were expanded and cryopreserved. Cells were then thawed and plated alongside adult human subcutaneous and omental pre-adipocytes for subsequent differentiation and phenotypic characterization. Interscapular preadipocytes in cell culture differentiated into mature adipocytes that were morphologically indistinguishable from the adult white depots. Throughout differentiation, cultured human fetal interscapular adipocytes demonstrated increased expression of classical brown fat markers compared to subcutaneous and omental cells. Further, functional analysis revealed an elevation in fatty acid oxidation as well as maximal and uncoupled oxygen consumption in interscapular brown adipocytes compared to white control cells. These data collectively identify the brown phenotype of these cells. Thus, our primary cell culture system derived from non-viable human fetal interscapular brown adipose tissue provides a valuable tool for the study of human brown adipocyte biology and for the development of anti-obesity therapeutics.