Characterization of Bone Marrow Progenitor Cell Uterine Engraftment and Transdifferentiation.

Regeneration of uterine tissue is an important physiological process that allows for maintenance of fertility after menstruation or pregnancy. Stem cells, especially bone marrow-derived progenitors, play a crucial role in this regeneration. Here, we describe the conversion of DsRed-labeled bone marrow-derived stem cells (BMDSCs) into specific uterine cell types with both differentiated and stem cell properties in a murine model. Irradiated recipient mice underwent bone marrow transplant with DsRed-expressing BMDSCs and were analyzed for engraftment and differentiation of BMDSCs in the uterus after 2, 6, and 16 weeks. Microarray and qRT-PCR analysis of bone marrow-derived cells obtained from the uterus identified upregulation of markers indicating a contribution to the population of stromal, epithelial, endothelial, and muscle cells, followed by a late expansion of epithelial cells. Other engrafted BMDSCs in the uterus were characterized by the continued expression of specific stem cell markers such as Sca1, CD44, CD146, and CD133, indicating the some BMDSCs remain as progenitor cells. BMDSCs established in recipient mice by the 16th week were sorted by flow cytometry using DsRed and progenitor cell surface markers. In vitro cell culture studies showed that single sorted cells had clonogenic properties. These results suggest that engrafted BMDSCs in the uterus had both a stem cell component and were able to differentiate into several differentiated cell types. The pool of progenitor cells likely continues to supply differentiated uterine cells in the process of uterine repair and remodeling.