Adipose stem cells originate from perivascular cells

Recent research has shown that adipose tissues contain abundant MSCs (mesenchymal stem cells). The origin and location of the adipose stem cells, however, remain unknown, presenting an obstacle to the further purification and study of these cells. In the present study, we aimed at investigating the origins of adipose stem cells. alpha-SMA (alpha-smooth muscle actin) is one of the markers of pericytes. We harvested ASCs (adipose stromal cells) from alpha-SMA-GFP (green fluorescent protein) transgenic mice and sorted them into GFP-positive and GFP-negative cells by FACS. Multi lineage differentiation tests were applied to examine the pluripotent ability of the alpha-SMA-GFP-positive and -negative cells. lmmunofluorescent staining for alpha-SMA and PDGF-R beta (platelet-derived growth factor receptor beta) were applied to identify the alpha-SMA-GFP-positive cells. Then alpha-SMA-GFP-positive cells were loaded on a collagen-fibronectin gel with endothelial cells to test their vascularization ability both in vitro and in vivo. Results show that, in adipose tissue, all of the alpha-SMA-GFP-positive cells congregate around the blood vessels. Only the alpha-SMA-GFP-positive cells have multilineage differentiation ability, while the alpha-SMA-GFP-negative cells can only differentiate in an adipogenic direction. The alpha-SMA-GFP-positive cells maintained expression of alpha-SMA during multilineage differentiation. The alpha-SMA-GFP-positive cells can promote the vascularization of endothelial cells in three-dimensional culture both in vitro and in vivo. We conclude that the adipose stem cells originate from perivascular cells and congregate around blood vessels.