Figure 6. A proposed model showing heterogeneous stem/progenitor cell populations of different origins in adipose tissue.

Various kinds of stem/progenitor cells are present in the putative perivascular niche of adipose tissue, such as tissue-resident mesoderm-derived cells, circulating bone marrow-derived cells [12], and NC-derived cells (“Fat tissue in vivo”). Endothelial cells could be an alternative source [11], [42]. Although the roles of these different cell populations in vivo remain largely unknown, they participate in generating phenotypic and functional diversity of ASCs in culture. NC-derived cells exhibit unique morphological and antigenic features and are largely restricted to the adipogenic lineage. The relationship among multipotent stem cells, osteogenic progenitors, and chondrogenic progenitors and their developmental origins are currently unknown (“Ex vivo”). Detailed characterization of different cell subpopulations is important for effective therapeutic application of ASCs.