Endometrial Stem Cells and Their Applications in Intrauterine Adhesion

Prevention of Intrauterine Adhesion with Platelet-Rich Plasma Double-Network Hydrogel

Intrauterine adhesion (IUA) can negatively impact on pregnancy outcomes, leading to reduced pregnancy rates, secondary infertility, and an increased risk of pregnancy complications. Studies have shown that the application of platelet-rich plasma (PRP) in IUA patients is effective. However, the clinical readhesive rate of IUA after treatment is still high, especially in severe cases. Platelet-rich plasma double-network hydrogel (DN gel) is an engineered PRP double network hydrogel, which is a sodium alginate (SA) based PRP hydrogel with egg carton ion cross-linking and fibrin double network. The results of this study show that intrauterine injection of DN gel has a better effect on promoting endometrial regeneration and enhancing endometrial receptivity than PRP gel. The mechanism is analyzed through single-cell sequencing, which may be achieved by increasing the expression of neutrophils (Neut), natural killer cells (NK), and type I classical dendritic cells (cDC1) in the endometrium and inhibiting the infiltration of M2 macrophages. Overall, based on the good healing efficiency and good biocompatibility of DN gel, it is expected to become a method of treating IUA with better efficacy and faster clinical translation.

The Impact of Adenomyosis on Pregnancy

Adenomyosis is characterized by ectopic proliferation of endometrial tissue within the myometrium. Histologically, this condition is marked by the presence of islands of benign endometrial glands surrounded by stromal cells. The myometrium appears thinner, and cross-sectional analysis often reveals signs of recent or chronic hemorrhage. The ectopic endometrial tissue may respond to ovarian hormonal stimulation, exhibiting proliferative or secretory changes during the menstrual cycle, potentially leading to bleeding, uterine swelling, and pain. Adenomyosis can appear as either a diffuse or focal condition. It is crucial to understand that adenomyosis involves the infiltration of the endometrium into the myometrium, rather than its displacement. The surgical management of adenomyosis is contingent upon its anatomical extent. The high incidence of the disease and the myths that develop around it increase the need to study its characteristics and its association with pregnancy and potential obstetric complications. These complications often require quick decisions, appropriate diagnosis, and proper counseling. Therefore, knowing the possible risks associated with adenomyosis is key to decision making. Pregnancy has a positive effect on adenomyosis and its painful symptoms. This improvement is not only due to the inhibition of ovulation, which inhibits the bleeding of adenomyotic tissue, but also to the metabolic, hormonal, immunological, and angiogenic changes associated with pregnancy. Adenomyosis affects pregnancy through disturbances of the endocrine system and the body's immune response at both local and systemic levels. It leads to bleeding from the adenomyotic tissue, molecular and functional abnormalities of the ectopic endometrium, abnormal placentation, and destruction of the adenomyotic tissue due to changes in the hormonal environment that characterizes pregnancy. Some of the obstetric complications that occur in women with adenomyosis in pregnancy include miscarriage, preterm delivery, placenta previa, low birth weight for gestational age, obstetric hemorrhage, and the need for cesarean section. These complications are an understudied field and remain unknown to the majority of obstetricians. These pathological conditions pose challenges to both the typical progression of pregnancy and the smooth conduct of labor in affected women. Further multicenter studies are imperative to validate the most suitable method for concluding labor following surgical intervention for adenomyosis.

A Novel Method to Repair Thin Endometrium and Restore Fertility Based on Menstruation-Derived Stem Cell

Thin endometrium (TE), which mainly occurs as a result of severe damage to the endometrial basalis, is one of the prominent etiologies of menstrual abnormalities, infertility, and recurrent miscarriage in women. Previous studies have demonstrated that mesenchymal stem cells (MSCs) are considered ideal cells with multipotency for regenerative medicine and exhibit therapeutic effects on TE through their cellular secretions. However, there is limited research on strategies to enhance MSC secretion to improve their therapeutic efficacy. Herein, we isolated menstrual blood-derived mesenchymal stem cells (MenSCs) from menstruation and transformed them into decidualized stromal cells (DSCs), which are specialized cells with enhanced secretory functions. To assess the therapeutic potential of DSCs compared to MenSCs, we conducted a series of experiments in cells and animals. The results demonstrated that DSCs exhibited changes in morphology compared to MenSCs, with a decrease in cell proliferation but a significant improvement in secretion function. Furthermore, DSCs facilitated the restoration of endometrial thickness and increased the number of glands and blood vessel formation. Most importantly, the pregnancy rates in rats were effectively restored, bringing them closer to normal levels. These findings greatly contribute to our understanding of stem cell therapy for TE and strongly suggest that DSCs could hold significant promise as a potential treatment option for TE.

Intrauterine adhesion

Intrauterine adhesions (IUA) occurred in the reproductive-age women are a big economic and health problem, resulting in severe impairment of social, psychological and physical function of the female genital organs. IUA-related symptoms or signs are varied greatly from free of symptoms or ambiguous symptoms (an incidental finding during the intervention) to ceased menstruation and loss of fecundability. The underlying pathophysiology is not completely understood, but intrauterine damage with broken basal layers of the endometrium formatting scar tissues or fibrosis in the endometrium with subsequently causing partial or complete occlusion of the uterine cavity may be a well-accepted hypothesis. Previously, infection is the most common cause to develop IUA, but now, intrauterine surgery may be a critical cause contributing to the majority of cases of IUA. In the current review, update information about the etiology, epidemiology, pathophysiology, sequelae and prevention of IUA will be renewed. We emphasize the importance of awareness of IUA, and primary prevention should be considered in the routine clinical practice if intrauterine surgery has been applied, based on uncertainty of ideal treatment for the established IUA and unpredictable outcomes after IUA treatment. So far, evidence supports that hyaluronic acid with/without other strategy is the most valuable and effective method to reduce the formation and re-formation of IUA as well as to achieve the best fertility outcome.

Endometrium procurement and transplantation restores fertility in rats

RESEARCH QUESTION

Can rat endometrium be successfully procured and transplanted, and can a similar method be used to procure human endometrium?

DESIGN

Rat endometrium was procured using an endometrium stripping method and transplanted into female Sprague-Dawley rats. Macroscopic and histological changes, endometrial receptivity-related protein concentrations and fertility were assessed. Additionally, a preliminary experiment was conducted to procure human endometrium using a similar method.

RESULTS

Endometrium was successfully procured from both rats and humans, which contained intact endometrium and parts of the adjacent inner annulus myometrium. Endometrium auto-transplantation was conducted in rats and the procedure lasted a total of 41.3 ± 5.7 min with a mean blood loss of 0.09 ± 0.04 g. The transplanted endometrium survived well, but a fibrotic zone formed between the transplant and recipient tissue. Compared with sham rats, those with endometrium transplantation had similar endometrial thickness and endometrial gland numbers but reduced vascular density at 8 weeks after surgery. Endometrium transplantation also retained expression of the endometrial receptivity-related proteins leukaemia inhibitory factor and vascular endothelial growth factor. In contrast to non-pregnancy in the stripped horn, a mean of 5.0 ± 2.7 fetuses developed in the transplanted horn, and full-term live fetuses were conceived in the horns with transplanted endometrium.

CONCLUSIONS

Endometrium procurement by stripping method can obtain an intact and functional endometrium, and endometrium transplantation can reconstruct the uterine cavity and restore fertility in rats.

MALAT1/miR-7-5p/TCF4 Axis Regulating Menstrual Blood Mesenchymal Stem Cells Improve Thin Endometrium Fertility by the Wnt Signaling Pathway

Thin endometrium (TE) is a significant factor contributing to fertility challenges, and addressing this condition remains a central challenge in reproductive medicine. Menstrual blood-derived mesenchymal stem cells (MenSCs) play a crucial role in tissue repair and regeneration, including that of TE. The Wnt signaling pathway, which is highly conserved and prevalent in eukaryotes, is essential for cell proliferation, tissue development, and reproductive functions. MALAT1 is implicated in various transcriptional and molecular functions, including cell proliferation and metastasis. However, the combined effects of the Wnt signaling pathway and the long non-coding RNA (lncRNA) MALAT1 on the regulation of MenSCs' regenerative capabilities in tissue engineering have not yet been explored. To elucidate the regulatory mechanism of MALAT1 in TE, we analyzed its expression levels in normal endometrium and TE tissues, finding that low expression of MALAT1 was associated with poor clinical prognosis. In addition, we conducted both in vitro and in vivo functional assays to examine the role of the MALAT1/miR-7-5p/TCF4 axis in cell proliferation and migration. Techniques such as dual-luciferase reporter assay, fluorescent in situ hybridization, and immunoblot experiments were utilized to clarify the molecular mechanism. To corroborate these findings, we established a TE model and conducted pregnancy experiments, demonstrating a strong association between MALAT1 expression and endometrial fertility. In conclusion, our comprehensive study provides strong evidence supporting that lncRNA MALAT1 modulates TCF4 expression in the Wnt signaling pathway through interaction with miR-7-5p, thus enhancing MenSCs-mediated improvement of TE and improving fertility.

Regeneration and anti-inflammatory effects of stem cells and their extracellular vesicles in gynecological diseases

There are many gynecological diseases, among which breast cancer (BC), cervical cancer (CC), endometriosis (EMs), and polycystic ovary syndrome (PCOS) are common and difficult to cure. Stem cells (SCs) are a focus of regenerative medicine. They are commonly used to treat organ damage and difficult diseases because of their potential for self-renewal and multidirectional differentiation. SCs are also commonly used for difficult-to-treat gynecological diseases because of their strong directional differentiation ability with unlimited possibilities, their tendency to adhere to the diseased tissue site, and their use as carriers for drug delivery. SCs can produce exosomes in a paracrine manner. Exosomes can be produced in large quantities and have the advantage of easy storage. Their safety and efficacy are superior to those of SCs, which have considerable potential in gynecological treatment, such as inhibiting endometrial senescence, promoting vascular reconstruction, and improving anti-inflammatory and immune functions. In this paper, we review the mechanisms of the regenerative and anti-inflammatory capacity of SCs and exosomes in incurable gynecological diseases and the current progress in their application in genetic engineering to provide a foundation for further research.