Current understanding of endometrial stem cells

Abstract

Somatic stem cells (SSCs) are defined as a rare population of undifferentiated cells residing in differentiated tissues and organs. Different studies and diverse approaches suggest the presence of SSCs in human and murine endometria. Owing to the lack of specific phenotypic markers to identify endometrial SSCs, they are defined by their functional properties. The embryological origin of the uterus and the putative implication of bone marrow in endometrial regeneration suggest their presumed mesenchymal origin. Nevertheless, more information is needed regarding the physiology of endometrial stem cells to understand the gynecological disorders associated with abnormal endometrial proliferation, such as endometriosis and endometrial cancer.

Perivascular Human Endometrial Mesenchymal Stem Cells Express Pathways Relevant to Self-Renewal, Lineage Specification, and Functional Phenotype1

“…Human endometrium regenerates on a cyclic basis from proposed progenitors of epithelial, fibroblast, and endothelial origins [6][7][8]. We found that eMSCs express markers of pericytes (e.g., RGS5, ACTA2, ANGPT2, IGFs, NGF and NGF high-affinity receptors, PDGF, PTHLH, TGFB, and syndecan) [48][49][50][51], and our immunofluorescence studies confirm the perivascular localization of these cells [21].…”

“…At menses and postpartum the endometrium exhibits a proinflammatory environment, extensive extracellular matrix remodeling, vasospasm, hypoxia, cell death, and tissue desquamation, with wound repair mechanisms and cellular proliferation and differentiation participating in its regeneration without scarring [2][3][4][5]. Stem/progenitor cells (epithelial, mesenchymal, endothelial) likely contribute to the rapid endometrial cyclic growth and regeneration of 4-14 mm of mucosa per cycle during the more than 400 cycles in a woman's reproductive lifespan and endometrial regeneration/ repair postpartum [6][7][8]. It is well known that bone marrowderived mesenchymal stem cells (MSCs) in the circulation can home to sites of damaged tissues [9], and it has been postulated that bone marrow-derived MSCs participate in cyclic endometrial repair and regeneration and may be progenitors of stromal fibroblasts and perhaps epithelial cells in the endometrium [7].…”

“…It is well known that bone marrowderived mesenchymal stem cells (MSCs) in the circulation can home to sites of damaged tissues [9], and it has been postulated that bone marrow-derived MSCs participate in cyclic endometrial repair and regeneration and may be progenitors of stromal fibroblasts and perhaps epithelial cells in the endometrium [7]. The phenotype of the stem/progenitors, what regulates their potential homing to endometrium, and mechanisms underlying their roles in endometrial tissue regeneration remain unresolved and are the subject of much investigation [6,8].…”

The Role of Stem Cells of the Basal Layer of Endometrium in Gynaecological Diseases

“…Since the content of MSC does not exceed a few parts of a percent, working with them implies isolation and cultivation in vitro. The most accessible sources of mesenchymal stem cells are fatty tissue, umbilical cord blood and placenta [16][17][18].…”