RESUMEN
In the body, different types of adipose tissue perform different functions, with brown and beige adipose tissues playing unique roles in dissipating energy. Throughout life, adipocytes are regenerated from progenitors, and this process is impaired by aging. One of the progenitors of adipocytes are mesenchymal stem cells (MSCs), which have recently become a promising tool for stem cell therapy. However, whether or not aging impairs the brown/beige adipocyte differentiation of adipose tissue-derived MSCs (AT-MSCs) remains unclear. In the present study, we isolated AT-MSCs from two different age groups of donors (infants and elderly subjects) and examined the effects of aging on the AT-MSC brown/beige adipocyte differentiation ability. We found that none of the AT-MSCs expressed Myf5, which indicated the beige (not brown) differentiation ability of cells. Of note, an inverse correlation was noted between the beige adipocyte differentiation ability and age, with AT-MSCs derived from elderly donors showed the most severely reduced function due to induced cellular senescence. The impaired expression of Sirtuin 1 (Sirt1) and Sirt3 proved to be responsible for the induction of senescence in elderly AT-MSCs; however, only Sirt1 was directly involved in the regulation of beige adipocyte differentiation. The overexpression of Sirt1 impaired the p53/p21 pathway, thereby preventing elderly AT-MSCs from entering senescence and restoring the beige differentiation ability. Thus, our study represents the important role of Sirt1 and senescence in the regulation of beige adipocyte differentiation during aging.