Abstract
Background:
Thin endometrium (TE) has been widely recognized as a critical cause of various obstetric and gynecological conditions. Although the role of stem cells in endometrial functions and their pathologies has been suggested, the identity and molecular mechanisms of such stem cells remain unclear.
Methods:
Data analysis of a publicly available single-cell RNA sequencing (scRNA-seq) was performed to unravel the cellular and molecular characteristics of endometrial CD9+ SUSD2+ cells in normal endometria (n = 3 ) across the menstrual cycle and proliferative phase of thin endometrium (n = 3 ). Then, CD9+ SUSD2+ cells were isolated for analysis. Flow cytometry and colony-forming assays were utilized to assess changes in CD9+ SUSD2+ cell proliferation and differentiation. Additionally, CellChat, Western blotting, and multiplex immunofluorescent analysis were performed to elucidate the tissue distribution of the CD9+ SUSD2+ cells and their molecular regulatory effects on the pathogenesis of TE.
Results:
A total of 59,770 cells were grouped into 13 distinct clusters in normal proliferative, secretory endometrium, and thin endometrium. Our findings revealed that perivascular CD9+ SUSD2+ cells as putative progenitor stem cells based on pseudotime trajectory and enriched functions in ossification, stem cell development, and wound healing. Histological analysis unveiled a significant perivascular expression pattern of CD9+ SUSD2+ cells in different menstrual cycle phases. The scRNA-seq of endometrial samples during the proliferative phase from patients with TE and controls revealed TE-associated shifts in cell function, manifesting as increased fibrosis and attenuated cell cycle and adipogenic differentiation. Cell-cell communication network mapping underscored aberrant crosstalk among specific cell types, implicating crucial pathways such as collagen over-deposition around perivascular CD9+ SUSD2+ cells, indicating a disrupted response to endometrial repair in TE, particularly remodeling of the extracellular matrix.
Conclusions:
Our study provides potential molecular mechanisms underpinning perivascular CD9+ SUSD2+ cells in the context of thin endometrium. The mechanistic insights could establish new therapeutic strategies for endometrial regeneration and repair.