Co-expression of two perivascular cell markers isolates mesenchymal stem-like cells from human endometrium

BACKGROUND: Human endometrium has immense regenerative capacity, growing similar to 5 mm in 7 days every month. We have previously identified a small population of colony-forming endometrial stromal cells which we hypothesize are mesenchymal stem cells (MSC). The aim of this study was to determine if the co-expression of two perivascular cell markers, CD146 and platelet-derived growth factor-receptor beta (PDGF-R beta), will prospectively isolate endometrial stromal cells which exhibit MSC properties, and determine their location in human endometrium. METHODS: Single cell suspensions of human endometrial stromal cells were fluorescence activated cell sorting (FACS) sorted into CD146(+)PDGF-R beta(+) and CD146(-)PDGF-R beta(-) populations and analysed for colony-forming ability, in vitro differentiation and expression of typical MSC markers. Full thickness human endometrial sections were co-stained for CD146 and PDGF-R beta. RESULTS: FACS stromal CD146(+)PDGF-R beta(+) stromal cells (1.5% of sorted population) were enriched for colony-forming cells compared with CD146(-)PDGF-R beta(-) cells (7.7 +/- 1.7 versus 0.7 +/- 0.2% P < 0.0001), and also underwent differentiation into adipogenic, osteogenic, myogenic and chondrogenic lineages. They expressed MSC phenotypic surface markers and were located near blood vessels. CONCLUSION: This study shows that human endometrium contains a small population of MSC-like cells that may be responsible for its cyclical growth, and may provide a readily available source of MSC for tissue engineering applications.