Defining Stem and Progenitor Cells within Adipose Tissue

Abstract

Adipose tissue-derived stem cells (ADSC) are routinely isolated from the stromal vascular fraction (SVF) of homogenized adipose tissue. Freshly isolated ADSC display surface markers that differ from those of cultured ADSC, but both cell preparations are capable of multipotential differentiation. Recent studies have inferred that these progenitors may reside in a perivascular location where they appeared to co-express CD34 and smooth muscle actin (α–SMA) but not CD31. However, these studies provided only limited histological evidence to support such assertions. In the present study we employed immunohistochemistry and immunofluorescence to define more precisely the location of ADSC within human adipose tissue. Our results show that α–SMA and CD31 localized within smooth muscle and endothelial cells, respectively, in all blood vessels examined. CD34 localized to both the intima (endothelium) and adventitia, neither of which expressed α–SMA. The niche marker Wnt5a was confined exclusively to the vascular wall, within mural smooth muscle cells. Surprisingly, the widely accepted mesenchymal stem cell marker STRO-1 was expressed exclusively in the endothelium of capillaries and arterioles but not in the endothelium of arteries. The embryonic stem cell marker SSEA1 localized to a pericytic location in capillaries and in certain smooth muscle cells of arterioles. Cells expressing the embryonic stem cell markers telomerase and OCT4 were rare and observed only in capillaries. Based on these findings and evidence gathered from the existing literature, we propose that ADSC are vascular precursor (stem) cells at various stages of differentiation. In their native tissue, ADSC at early stages of differentiation can differentiate into tissue-specific cells such as adipocytes. Isolated, ADSC can be induced to differentiate into additional cell types such as osteoblasts and chondrocytes.

Phenotypic Characterization and In Vivo Localization of Human Adipose-Derived Mesenchymal Stem Cells

“…Some investigations have shown that hADMSCs recovered from the SVF are likely to be considered "pericytes" or "perivascular progenitor cells" (Caplan et al, 2008;Crisan et al, 2008;Lin et al, 2008). However, it is still unclear whether or not isolated hADMSCs are truly "pericytes" and from where hADMSCs originate (Locke et al, 2011;Tholpady et al, 2006).…”

Phenotypes of stem cells from diverse origin

“…Therefore, we asked all authors to revisit the table and upgrade their part either by own data or based on additional literature, as necessary. This resulted in the upgraded Table 1 showing phenotypes of very small embryonic-like stem cells (vSELs) (5,6), neural stem cells (NSCs) (7)(8)(9)(10)(11)(12)(13)(14)(15)(16), hematopoietic stem cells (HSCs) from two organs (4,17), MSCs (4,18), EpSC (4), limbal epithelial stem cells (LSCs) (19), endothelial progenitor cells (EPCs) from different organs (3,4,(20)(21)(22)(23)(24)(25), supra-adventitial adipose stromal cells (SA-ASCs) (3,(22)(23)(24)(25), adipose pericytes (pericyte) (3,(22)(23)(24)(25), and finally cancer stem cells (CSCs) (26).…”

“…VI (4) VII (19) VIII (20,21) IX (3,(22)(23)(24)(25) X (4) XI (3,(22)(23)(24)(25) XII (3,(22)(23)(24)(25) XIII ( (17) IV (4) V (4,18) VI (4) VII (19) VIII (20,21) IX (3,(22)(23)(24)(25) X (4) XI (3,(22)(23)(24)(25) XII (3,(22)(23)(24)(25) XIII (26) RHAMM/HMMR marker expression in the same stem cell lineage obtained from various tissues may indicate differences in their pluripotency. It is also possible that stem cell marker expression pattern and levels depend on respective cell cycle phases.…”

Stem cells: novel players in the treatment of erectile dysfunction

“…35,36 Recently, MSCs derived from the stromal vascular fraction of adipose tissue, termed as adipose tissue-derived stem cells (ADSCs), represent an abundant and easily accessible source of stem cells. 37 While bone marrow is obtainable in the gram range by a painful marrow aspiration procedure, adipose tissue can be obtained in the range of hundreds of grams with a minimally invasive procedure. The possibility of harvesting hundreds of grams of adipose tissue excludes the need for MSC isolation and culture steps and allows for the direct re-injection of the stromal vascular fraction during the same surgical procedure in which they were harvested.…”

“…Therefore, it is reasonable to expect that ADSCs will become the preferred choice of ASCs for future clinical applications. 37 Localisation of ASCs in their native tissue-stem cell niche The stem cell niche is a microenvironment that maintains stem cells in a quiescent state. After tissue injury, the niche promotes either selfrenewal or differentiation to form new tissues.…”