Dedifferentiated fat (DFAT) cells: potential involvement in intramuscular adipogenesis

Abstract Text: Intramuscular adipogenesis and the dynamics of lipid metabolism by mature adipocytes have been investigated primarily due to the importance of altering marbling to enhance meat quality. Knowledge regarding intramuscular fat development has relied on the conversion of a variety of preadipocyte-like cells (such as stromal vascular cells) and their differentiation into lipid-assimilating adipocytes, which was thought to be the end of their cell cycle. However, a great number of studies have demonstrated the ability of the mature adipocyte to dedifferentiate into a population of a proliferative-competent cells known as the dedifferentiated fat (DFAT) cells. As early as the 1970’s in vitro studies have shown that DFAT cells may be obtained by ceiling culture, which takes advantage of the buoyancy property of lipid-filled cells. It is documented that DFAT cells may acquire a phenotype similar to mesenchymal stem cells and may redifferentiate into multiple cell lineages. From an animal science/meat science perspective, the main question that arises from the current knowledge of DFAT cells is: how do DFAT cells contribute to intramuscular fat accumulation? What regulation causes the intramuscular mature adipocytes to dedifferentiate or resume their capability to proliferate? Moreover, are DFAT cells controllable so that they differentiate into lipid-assimilation cells (and perhaps other cells) and thus contribute to overall increase of intramuscular fat in vivo? Considering the fact that marbling fat accumulation is the last step in meat production, a (muscle and fat cell) intercellular regulation might trigger the differentiation of intramuscular adipocytes (regardless of origin). For example, feed restriction followed by re-alimentation may lead to dedifferentiation of mature adipocytes followed by its redifferentiation of proliferative competent (DFAT) progeny cells [as well as other preadipocytes/adipofibroblasts] into lipid-assimilating cells upon realimentation, which may be one of the causes of changing the body composition and increase of fatness. DFAT cells originating from different adipose depots possess different rates of redifferentiation, whereas those originated from intramuscular fat depot are more active in adipogenesis than other fat depots. In summary, although the mechanisms of dedifferentiation of mature adipocytes has not been well defined, DFAT cells may contribute to intramuscular adipogenesis. DFAT cells  may lead to the adoption of strategies in livestock production in order to enhance fat deposition in specific (desired) depots.

Keywords: adipose tissue, ceiling culture, marbling