Decidualization potential of endometrial mesenchymal stem cells and their role in reproductive health

Abstract

The establishment of a successful pregnancy depends on proper embryo development and coordinated endometrial differentiation, particularly through the process of decidualization. Mesenchymal stem/stromal cells (MSCs), especially those derived from endometrial tissue (eMSCs) and menstrual fluid (MenSCs), have emerged as critical players in regulating decidualization, trophoblast invasion, angiogenesis, and immune modulation at the maternal–fetal interface. These cells exhibit potent immunoregulatory functions, underscoring their role in establishing a tolerant yet responsive environment for implantation along with promoting angiogenesis and stromal regeneration. Dysfunctional MSCs have been linked to impaired decidualization and pregnancy disorders, including preeclampsia (PE) and fetal growth restriction. Evidence indicates that MenSCs from women with a history of PE exhibit diminished angiogenic potential, impaired trophoblast invasion support, and altered cytokine secretion, associating these alterations to disease pathogenesis. Similarly, aberrant eMSCs contribute to endometriosis by supporting ectopic implantation, impaired decidualization, and enhanced migration.

Collectively, these findings highlight the central role of endometrial- and menstrual-derived MSCs in both reproductive success and pathology. They also emphasize their potential as diagnostic biomarkers and therapeutic targets in obstetrics and gynecology. In this review, we summarize current knowledge on the role of endometrial- and menstrual-derived MSCs in pregnancy establishment and related complications, and discuss their emerging promise as diagnostic tools and therapeutic strategies in reproductive medicine.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12958-026-01566-5.

Introduction

The establishment of a successful pregnancy requires the coordination of two critical processes: embryo development and endometrial differentiation [1, 2]. The current paradigm of embryo–endometrium interaction during implantation and placentation has primarily focused on the activity and role of the embryo [3]. This paradigm has been challenged by growing evidence highlighting the cardinal role of decidualizing endometrial cells in reproductive success including they role in embryo biosensoring and selection [2, 4, 5]. The decidualization process involves the differentiation of fibroblast-like mesenchymal cells in the uterine stroma into rounded, epithelioid-like cells during the mid-secretory phase of the cycle [5, 6]. This phase, characterized by elevated levels of estrogen and progesterone, and by the presence of endometrial stromal cells (ESCs) surrounding the spiral arteries, occurs independently of the conceptus [6]. Decidualization is essential for the establishment of a pregnancy, preparing the endometrium hormonally, biochemically, and immunologically in anticipation of embryo implantation [6, 7]. Failure to achieve adequate decidualization has been linked to implantation failure [8], infertility [9] and recurrent miscarriages [10]. A more comprehensive understanding of endometrial regeneration and decidualization is key for uncovering the etiology of these conditions and preventing such disorders.

The use of mesenchymal stem cells (MSCs) has been actively explored for the study of gynecological and obstetric disorders [11, 12]. Beyond their therapeutic potential, MSCs may also be important tools for understanding endometrial remodeling through the female life cycle. Emerging evidence suggests that endometrial MSCs (eMSCs) may act as key regulators of decidual competence [13]. The aim of this review is to synthesize and update the current literature on the role of endometrial- and menstrual-derived MSCs reproductive biology, with a particular focus on preeclampsia (PE) and endometriosis.

Endometrial-derived mesenchymal stem cells

MSCs are plastic adherent clonogenic cells with a characteristic surface phenotype, that are capable of differentiating into multiple mesodermal lineages, like adipocytes and osteoblast in vivo, and chondrocytes in vitro [14]. MSCs can be isolated from different body tissues such as bone marrow, adipose tissue, amniotic fluid, or endometrium [15]. These cells are recognized as potent tools in regenerative medicine and their characteristics can be slightly different depending on the source of tissue [16]. Despite sharing core phenotypic markers, MSCs from different sources display a tissue-specific secretome -comprising cytokines, growth factors and extracellular matrix related proteins- that reflect their tissue origin and functional specialization [17].

Over the past decade, a subpopulation of endometrial cells with MSC characteristics has been identified and isolated from both human endometrial tissue (eMSC) and menstrual fluid (MenSC) [18]. When derived from hysterectomy specimens containing both functionalis and basalis layers, eMSC comprise 1.3% of stromal fibroblasts. In contrast, the upper two-thirds of the functionalis layer are shed during menstruation [12], making menstrual blood an accessible, non-invasive source of eMSCs, easily collected using a menstrual cup. These cells -MenSCs- display highly clonogenic properties, similar to those of bone marrow-derived MSCs [19], retain multipotent differentiation capacity (e.g., adipocytes and chondrocytes); exhibit immunophenotypic characteristics of MSCs (but not hematopoietic cells); and are adherent to plastic in culture [18, 20]. In addition, MenSCs exhibit angiogenic properties, including VEGF secretion [21] and can be passaged at least 12 times without any signs of stem cell exhaustion [19, 22]. Collectively, these properties position MenSCs as a promising alternative to other sources such as bone marrow-, adipose- and birth tissue-derived MSCs, due to their higher proliferative rates, angiogenic potential, and accessibility without the need for invasive procedures or hospitalization [22].

In the endometrium, eMSCs are key regulators of the finely tuned immune balance required for successful implantation and trophoblast invasion [18]. The eMSC secretome exerts potent immunomodulatory effect on stromal cells, reshaping inflammatory and cytokine-related expression to promote an immune-tolerant endometrial microenvironment supportive of implantation [23]. In addition, the paracrine activity of eMSCs contributes to their regenerative capacity, particularly through roles in angiogenesis and stromal repair -processes essential for maintaining endometrial integrity and function [24, 25]. eMSCs exhibit strong angiogenic potential, largely mediated by through the secretion of VEGF and other pro-angiogenic factors [26]. Similarly, MenSCs have demonstrated therapeutic potential in wound healing and cutaneous regeneration, associated with increased secretion of Il-8 and Vegf [27], even surpassing bone marrow derived-MSCs [28]. Furthermore, both paracrine signaling and cell-to-cell interaction of eMSCs contribute to the decidualization process [29, 30]. Conversely, eMSC dysfunction -driven by chronic inflammation or hormonal dysregulation- can result in defective decidualization, thereby disrupting trophoblast development and ultimately impairing implantation [31, 32].

eMSC and decidualization key processes

Recent studies suggest that the decidua orchestrates key events in pre- and early-pregnancy, with its primary function being to assess embryo quality and ensure maternal resources are invested only in viable embryos [5, 33, 34]. In healthy pregnancies, uterine spiral arteries undergo structural changes whereby the endothelial layer is replaced by a subtype of placental trophoblasts, endovascular extravillous trophoblasts (enEVTs), while a fibrinoid matrix replaces the muscular layer. Impaired uterovascular remodeling may result from defective EVT invasion or inadequate decidualization. Human decidualization occurs during the secretory phase of the menstrual cycle, when endometrial stromal cells (ESCs) spontaneously differentiate into decidual cells in response to progesterone and estrogen. This process can be recapitulated in vitro by elevating cyclic adenosine monophosphate (cAMP) levels, thereby preparing the endometrium for potential embryo implantation [6, 31]. This process is accompanied by a morphological transition of ESCs to secretory decidual stromal cells, secretory transformation of the uterine glands, recruitment of specialized uterine natural killer (uNK) cells, and elongation of the uterine spiral arteries to support maternal blood supply to the growing conceptus [35]. In the absence of a conceptus, decidualized cells are shed (i.e., menstruation), in a process that is triggered by progesterone withdrawal at the end of the luteal phase [5]. ESCs are the primary effectors of decidualization, whereas studies of SUSD2 + eMSCs indicate that these progenitor cells retain their stem-like identity during decidualization, supporting stromal renewal and decidual competence [30] (Fig. 1).

Fig. 1.

Endometrial MSCs are relevant actors in key processes of healthy pregnancy, such as implantation, decidualization, and placentation. Their dysfunction is associated with several gynecological and pregnancy related disorders, such as preeclampsia, endometriosis, and fetal growth restriction. Understanding the underlying mechanisms altering MSC functionality and promoting these diseases is essential for developing novel screening and treatment strategies

In human cell cultures, the use of progesterone and intracellular cAMP induces ESCs decidualization, leading to increased expression of decidual markers including prolactin (PRL) and insulin-like growth factor-binding protein 1 (IGFBP-1) [5]. Upon differentiation in vitro, human ESCs have been described as a close phenocopy of the decidual response observed in vivo. Endometrial research has therefore focused on the factors regulating embryo implantation, emphasizing the importance of decidualization and placentation for pregnancy success using MSCs [5, 6, 9]. Conversely, defective decidualization and aberrant decidual responses have been implicated in various obstetrical and gynecological syndromes [36], including PE [37], fetal growth restriction (FGR) [38], implantation failure and recurrent miscarriage [39, 40], and endometriosis [41, 42].

Research advances on menstrual stem cells in the aetiology of preeclampsia

PE complications and its associated pathologies remain among the leading causes of maternal and fetal morbidity and mortality worldwide [43]. Substantial evidence additionally supports a strong association between PE and increased risk of cardiovascular disease later in life, independent of traditional risk factors [44–46]. PE affects 5–8% of all pregnancies and is defined as a new onset of hypertension (systolic blood pressure of 140 mm Hg or more or a diastolic blood pressure of 90 mm Hg or more) during the second half of pregnancy, accompanied by proteinuria or other end-organ dysfunction [47]. From a pathophysiological point of view, PE originates early in gestation, typically during the first trimester with an asymptomatic phase characterized by defective trophoblast invasion and incomplete remodeling of the spiral arteries [48, 49], both of which are related to the invasive potential of EVT [50] (Fig. 1). Understanding the factors that regulate this process in normal pregnancies and in patients with PE is critical to develop preventative or early therapeutic interventions, aimed at reducing not only perinatal morbidity and mortality but also the long-term cardiovascular risk associated with this condition.

A more comprehensive understanding of how EVT invasion and fetal growth are regulated is essential for developing effective early intervention strategies. Following blastocyst apposition to the maternal decidua, cytotrophoblasts form cell columns from the tips of anchoring villi, which subsequently migrate and invade the maternal decidua [51]. EVT cells derived from these columns penetrate the decidua and further differentiate into interstitial and endovascular trophoblast cells. From 8 weeks of pregnancy, the compact decidual tissue becomes densely populated by interstitial EVTs, which cluster around maternal blood vessels [52, 53], while endovascular trophoblast cells migrate into the maternal spiral arteries to plug these vessels. Between 10 and 12 weeks of gestation, these plugs begin to dissolve as EVTs replace the maternal endothelium, degrading the muscular and elastic component of the vessel wall. This remodeling process results in the formation of low-resistance vessels essential for adequate uteroplacental circulation and fetal growth, marking the onset of maternal blood flow into the intervillous space [54].

The human endometrium plays a critical role in trophoblast migration and invasion [55]. Composed of epithelial and stromal cells embedded within an extracellular matrix, the endometrium becomes receptive to the embryo under the influence of estradiol and progesterone during the window of implantation [3, 56]. These changes are crucial to regulate trophoblast migration and invasion. Trophoblast migration refers to the process of normal cell movement following a chemotactic gradient, whereas trophoblast cell invasion involves the ability to traverse the endometrium’s extracellular matrix and the infiltration of neighboring tissues such as maternal blood vessels [51, 57].

Impaired decidualization, as mentioned before, has been described in PE [37, 58, 59], with these abnormalities detectable at delivery and persisting for years after the affected pregnancy. Interestingly, ESCs obtained from non-pregnant women with a history of severe PE do not decidualize in vitro in response to cAMP and medroxyprogesterone acetate (MPA), and release significantly lower levels of the decidualization markers PRL and IGFBP-1 than those derived from women with a previous normal pregnancy [60]. Altered transcriptional profiles of genes involved in decidualization have also been reported in PE [61–63]. Moreover, circulating concentrations of IGFBP-1 are lower in pregnant patients who subsequently develop PE than in those with a normal pregnancy outcome [64, 65]. Using a systems biology approach to integrating gene expression profiles of the endometrium throughout the menstrual cycle suggest that PE is preceded by dysregulated endometrial maturation, consistent with impaired pre-decidualization. In summary, decidualization defects have been detected in patients with a history of PE and have been proposed to persist years after the affected pregnancy. Together, these data support the hypothesis that during pregnancy endometrial cells reflect abnormal processes occurring in PE and that the abnormal phenotype may remain years after pregnancy. Appropriate trophoblast invasion relies on an orchestrated communication between EVT and decidual cells, and it has been postulated that this communication mechanism is mediated, at least in part, through eMSCs present in the decidua along with immunological factors.

Our laboratory has been investigating the relationship between the angiogenic properties of MenSCs and the physiopathology of PE. We have characterized the phenotype of MenSCs isolated from women with a history of PE in comparison with MenSCs isolated from healthy donors, evaluating their morphological, immunophenotypic, and functional characteristics, including angiogenic potential, such as tube formation capacity and secretion of VEGF, endoglin, and cytokines [21]. In this study, we demonstrated that both populations shared similar lineage differentiation potential and immunophenotypic profiles, as assessed by flow cytometry. Also, MenSCs isolated from women with a history of PE showed reduced VEGF expression, lower membrane-bound endoglin levels, diminished endothelial cell tube formation, and an increased secretion of pro-inflammatory cytokines (IL-1β, GM-CSF, and IL-6) [21]. Moreover, MenSCs isolated from women with history of PE showed a reduced capacity to promote trophoblast invasion [66]. In a 3D invasion model using trophospheres cultured on a layer of matrigel overlying MenSCs from women with a history of PE after treatment with estradiol and progesterone, the area of invasion was significantly reduced after 72 hours compared to co-cultures with MenSCs from healthy women [66]. In this model, we observed that trophoblast cells failed to invade in the absence of MenSCs, suggesting that communication between maternal MenSCs and invading trophoblast cells plays a crucial role during the implantation process [66]. Based on this, we propose that MenSCs stimulate trophosphere invasion probably through the release of small extracellular vesicles (sEVs) or other paracrine factors. Indeed, previous studies have demonstrated that exosomes secreted by MenSCs represent an important novel type of intercellular communication [67, 68]. However, the molecular content and functional relevance of MenSC-derived sEVs, particularly in regulating trophoblast invasion, remain poorly characterized. Analysis of these vesicles could provide insights into the mechanisms underlying the altered invasion capacity of trophoblasts in PE. Notably, sEVs have been shown to regulate molecular mechanisms involved in embryo implantation, highlighting their potential role in the pathophysiology of PE [69–71]. Proteomic analysis of sEVs isolated from primary human endometrial epithelial cells has shown an enrichment of proteins involved in biological processes critical in embryo implantation, including cell adhesion, differentiation, communication, migration, and reproductive processes [72].

Endometrium- and menstrual-derived stem cells in the origins of endometriosis

Endometriosis (EM) is a gynecological disease defined as the growth of stroma and epithelial glands outside the uterus, and is typically associated with chronic pelvic pain, infertility, and mental health comorbidities such as depression and anxiety [73–77]. It affects approximately 10% of women of reproductive age and is characterized by the presence of hormonally responsible endometrial-like tissue at ectopic sites. These lesions are most commonly found within the peritoneal cavity, including the surface of ovaries, fallopian tubes, intestine, rectum-sigmoid, uterine ligaments and recto-vaginal septum, but it can also occur at extra pelvic locations such as in the intestine, diaphragm, lung, and, more rarely, the central nervous system [77, 78].

Although the pathogenesis of EM has not been completely elucidated, the most widely accepted hypothesis is the Sampson’s theory of retrograde menstruation [79]. This theory postulates that menstrual fluid (MF) flows backward through the Fallopian tubes into the peritoneal cavity, allowing endometrial fragments to implant ectopically (Fig. 1). However, although retrograde menstruation is present in all women, only 10% develop EM [80], suggesting that additional factors must contribute to disease establishment, indicating that retrograde flow is necessary but not sufficient for EM to develop. The identification of eMSCs in the functionalis layer of endometrium (eutopic) [81], in MF [82], and in the ectopic lesions of women with EM [83], has not only confirmed Sampson’s theory but also suggested a key role for stem cells in the onset of EM [84–86]. The stem cell theory proposes that a small number of stem and progenitor cells originated from the eutopic endometrium, can establish an endometriotic lesion during retrograde menstruation, complementing and reinforcing Sampson’s theory [12]. MF is a heterogenous biological fluid composed of blood, vaginal secretions, immune cells, and functionalis layer-endometrial cells (epithelial and stromal) as they exist immediately prior to menses [87, 88]. Indeed, recent studies have demonstrated that MF-derived stromal fibroblast cells cultured from EM patients displayed impaired decidualization potential compared with controls [41, 42]. In light of the above, it is tempting to speculate that the onset of EM resides in the eutopic endometrium itself, with aberrant migration, invasion and impaired decidualization of menstrual cells that are cyclically shed into the peritoneal cavity, being root causes of the establishment and maintenance of ectopic implants. Further supporting this concept, Kao et al. compared eMSCs isolated from paired eutopic endometrial and ectopic endometriotic biopsies and found that ectopic eMSCs displayed significantly greater migratory and invasive capacities than their eutopic counterparts, implying aberrant cellular behavior within endometriotic lesions [89]. Similarly, Liu et al., demonstrated that eMSCs derived from endometrial biopsies obtained from patients with EM display aberrant proliferation, migration, and angiogenesis compared to endometrial biopsy-derived eMSCs obtained from control subjects [83].

In conclusion, increasing evidence suggests a pivotal role of endometrial- and menstrual blood-derived stem cells in the development of endometriosis. Further investigation into the cellular origins of this condition, specifically the cell types shed into the pelvic cavity and the mechanisms that support their ectopic survival, implantation and proliferation is key to refine our understanding of this debilitating disease, and advance early diagnostic, preventive, and therapeutic strategies.

Clinical perspective

From a clinical perspective, eMSCs act as central regulators of endometrial regeneration and decidualization throughout the female lifespan. Dysregulation of eMSCs function may represent a common upstream mechanism linking endometriosis and PE, through impaired progesterone responsiveness, defective decidualization and the acquisition of a pro-inflammatory phenotype. The study of MenSCs offers a valuable, non-invasive approach to characterize a disease-associated alterations and to identify early biomarkers of reproductive risk. Furthermore, this perspective opens opportunities for the development of personalized strategies aimed at restoring endometrial homeostasis, thereby improving pregnancy outcomes, and reducing long-term reproductive and cardiometabolic consequences associated with these conditions.

Conclusions

Endometrial- and menstrual-derived MSCs play a pivotal role in reproductive biology by regulating decidualization, immune tolerance, angiogenesis, and trophoblast invasion. Dysfunction of these cells contributes to major reproductive disorders, including PE and endometriosis. In PE, MenSCs exhibit reduced angiogenic and pro-decidualization capacity, impairing trophoblast invasion and spiral artery remodeling. In endometriosis, dysregulated eMSC promotes increased migration, and invasion, providing a complementary mechanism to the retrograde menstruation hypothesis. Collectively, these findings position eMSCs as both pathophysiological drivers and promising targets for therapeutic innovation. In particular, eMSC-derived extracellular vesicles represent emerging candidates as biomarkers and modulators of implantation, offering potential avenues for earlier diagnosis and novel treatment strategies to improve reproductive outcomes.

Authors' contributions

RP, SEI and LJM (Conceptualization, Writing-original draft, Writing-review & editing). MC, MWK, FV, VP, and IV (Writing-original draft).

Funding

This work was supported by National Agency for Research and Development (ANID) through “Fondo Nacional de Desarrollo Científico y Tecnologico” [FONDECYT 1241103 (SIL) and 1230932 (LJM), FONDECYT Postdoctoral 3230201 (RP)], Subdirección de Capital Humano/Becas Doctorado Nacional/2023 21230458 (VP), and Basal Funding for Scientific and Technological Center of Excelence, IMPACT, #FB210024.

Data availability

No datasets were generated or analyzed during the current study.

Declarations

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Competing interests

The authors declare no competing interests.