Mesenchymal markers on human adipose stem/progenitor cells

The stromal‐vascular fraction (SVF) of adipose tissue is a rich source of multipotent stem cells. We and others have described three major populations of stem/progenitor cells in this fraction, all closely associated with small blood vessels: endothelial progenitor cells (EPC, CD45−/CD31+/CD34+), pericytes (CD45−/CD31−/CD146+), and supra‐adventitial adipose stromal cells (SA‐ASC, CD45−/CD31−/CD146−/CD34+). EPC are luminal, pericytes are adventitial, and SA‐ASC surround the vessel like a sheath. The multipotency of the pericytes and SA‐ASC compartments is strikingly similar to that of CD45−/CD34−/CD73+/CD105+/CD90+ bone marrow‐derived mesenchymal stem cells (BM‐MSC). Here, we determine the extent to which this mesenchymal pattern is expressed on the three adipose stem/progenitor populations. Eight independent adipose tissue samples were analyzed in a single tube (CD105‐FITC/CD73‐PE/CD146‐PETXR/CD14‐PECY5/CD33‐PECY5/CD235A‐PECY5/CD31‐PECY7/CD90‐APC/CD34‐A700/CD45‐APCCY7/DAPI). Adipose EPC were highly proliferative with (14.3 ± 2.8)% (mean ± SEM) having >2 N DNA. About half (53.1 ± 7.6)% coexpressed CD73 and CD105, and (71.9 ± 7.4)% expressed CD90. Pericytes were less proliferative [(8.2 ± 3.4)% >2 N DNA)] with a smaller proportion [(29.6 ± 6.9)% CD73+/CD105+, (60.5 ± 10.2)% CD90+] expressing mesenchymal associated markers. However, the CD34+ subset of CD146+ pericytes were both highly proliferative [(15.1 ± 3.6)% with >2 N DNA] and of uniform mesenchymal phenotype [(93.3 ± 3.7)% CD73+/CD105+, (97.8 ± 0.7)% CD90+], suggesting transit amplifying progenitor cells. SA‐ASC were the least proliferative [(3.7 ± 0.8)%>2 N DNA] but were also highly mesenchymal in phenotype [(94.4 ± 3.2)% CD73+/CD105+, (95.5 ± 1.2)% CD90+]. These data imply a progenitor/progeny relationship between pericytes and SA‐ASC, the most mesenchymal of SVF cells. Despite phenotypic and functional similarities to BM‐MSC, SA‐ASC are distinguished by CD34 expression. © 2012 International Society for Advancement of Cytometry