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

BACKGROUND: Human endometrium has immense regenerative capacity, growing ~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-Rbeta), 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-Rbeta(+) and CD146(-)PDGF-Rbeta(-) 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-Rbeta.

RESULTS: FACS stromal CD146(+)PDGF-Rbeta(+) stromal cells (1.5% of sorted population) were enriched for colony-forming cells compared with CD146(-)PDGF-Rbeta(-) 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.