Human endometrium undergoes extensive regeneration on a cyclic basis in premenopausal women and likely occurs through the contribution of stem/progenitor cells. Menopause results in the permanent cessation of menstrual cycles and is preceded by perimenopause, a period of several years inwhich endocrine and biological changes occur and is a period of risk for endometrial proliferative disorders. The objectives of this study were to identify endometrial mesenchymal stem cells (eMSC) and endometrial stromal fibroblasts (eSF) in endometrium of perimenopausal women and perform expression profile analysis of perimenopausal eMSC and eSF to gain insight into the biology of stem/progenitor and lineage cell populations during the transition to menopause. Endometrial tissue was collected from perimenopausal and premenopausal women (n = 9 each). Microarray analysis was performed on fluorescence-activated cell sorting-isolated eSF and eMSC, and data were validated by quantitative real-time PCR. Principal component analysis showed that cells clustered into three distinct groups in 3-dimensional space: perimenopausal eMSC and premenopausal eMSC clustered together, while perimenopausal eSF and premenopausal eSF formed two discrete clusters separate from eMSC. Hierarchical clustering revealed a branching pattern consistent with principle clustering analysis results, indicating that eMSC from premenopausal and perimenopausal women exhibit similar transcriptomic signatures. Pathway analysis revealed dysregulation of cytoskeleton, proliferation, and survival pathways in perimenopausal vs. premenopausal eSF. These data demonstrate that cell populations have altered gene expression in perimenopausal vs. premenopausal endometrium, and that perimenopausal eSF had altered pathway activation when compared to premenopausal eSF. This study provides insight into aging endometrium with relevance to function in reproductively older women.

Summary Sentence

The hormonal milieu during the transition to menopause has an effect on endometrial stromal fibroblast gene expression and a minimal effect on the endometrial mesenchymal stem cell population, offering insight into the mechanisms by which the endometrium remains functional after menopause.