Adipocytes may not be a terminally differentiated cell type: implications for animal production

Abstract

Mature adipocytes may not be a terminally differentiated cell form, as previously thought by about everyone in science. Instead, these adipocytes may be capable of re-entering the cell cycle and forming proliferative-competent precursor cells like preadipocytes, adipofibroblasts, or even other forms of cells. Why is this possibility important to animal science? The main reason is in directing the cellularity of adipocyte depots in meat animals. For example, we know that the fat characteristics of beef animals are a direct function of the ‘cellularity’ of cells committed to form adipocytes. Beef steers given a high-concentrate diet commonly possess fewer adipocytes in any given fat depot, but most of the cells are completely filled with lipid to capacity. Alternatively, steers on a high-roughage diet seem to possess more fat cells, but fewer of them are filled to capacity with storage lipid. A variety of systemic and local regulators have been implicated in altering the cellularity of any given fat depot. Major regulators appear to be growth hormone, any number of repartitioning agents, as well as adipocytokines produced by the cells within the fat depot themselves. The specific mechanisms involved in directing cellularity of any specific fat depot, however, are poorly understood.