Decidua parietalis-derived mesenchymal stromal cells reside in a vascular niche within the choriodecidua

Mesenchymal stromal cells (MSCs) from gestational tissues represent promising cell populations with stem cell-like properties for use in regenerative medicine. Previously, we reported that MSCs in the chorionic villi of the human placenta reside in a vascular niche. However, the niche(s) in which MSCs reside in the fetal membranes, another rich source of MSCs, remains to be determined. The cell surface markers STRO-1 and 3G5 were previously employed to identify niches in a variety of tissues and here we use these markers to report the location of the MSC niche in the human decidua parietalis. The cultured decidua parietalis MSCs (DPMSCs) isolated from the choriodecidua component of the fetal membranes possessed stem cell-like properties such as adherence to plastic, colony forming ability, and multipotent differentiation potential. Fluorescence in situ hybridization analysis showed cultured DPMSCs were of maternal origin. Immunocytochemistry demonstrated that cultured DPMSCs stained positively with stem cell surface markers 3G5, CD105, CD106, STRO-1, CD146, CD49a, and α-SMA but were negative for hematopoietic markers (CD117, CD34) and vascular markers (CD34, von Willebrand factor [vWF]). Immunohistochemistry with antibodies to stem cell surface markers and the endothelial markers on term fetal membranes revealed a vascular niche for DPMSCs, which was confirmed by immunofluorescence analysis. Both STRO-1 and vWF fluorescence signals showed substantial overlap, while CD146 and vWF signals showed partial overlap. These observations were consistent with a vascular niche.