Bone marrow mesenchymal stem cells combined with estrogen synergistically promote endometrial regeneration and reverse EMT via Wnt/β-catenin signaling pathway

Combination Therapy of Bone Marrow Mesenchymal Stem Cell Transplantation and Electroacupuncture for the Repair of Intrauterine Adhesions in Rats: Mechanisms and Functional Recovery

Transplantation of bone marrow mesenchymal stem cells (BMSCs) has demonstrated promising clinical utility in the treatment of endometrial injury and the restoration of fertility. However, since the efficacy of BMSCs after transplantation is not stable, it is very important to find effective ways to enhance the utilisation of BMSCs. Electroacupuncture (EA) has some positive effects on the chemotaxis of stem cells and diseases related to uterine injury. In this study, we established the intrauterine adhesion (IUA) model of the Sprague-Dawley rat using lipopolysaccharide infection and mechanical scratching. Phosphate-buffered saline, BMSCs alone, and BMSCs combined with EA were randomly administered to the rats. Fluorescent cell labelling showed the migration of transplanted BMSCs. H&E staining, Masson staining, Western blot, immunohistochemistry, ELISA, and qRT-PCR were utilised to detect changes in endometrial morphology and expressions of endometrial receptivity-related factors, endometrial pro-inflammatory factors, and fibrosis factors. Finally, we conducted a fertility test to measure the recovery of uterine function. The results showed that EA promoted transplanted BMSCs to migrate into the injured uterus by activating the SDF-1/CXCR4 axis. Endometrial morphology showed the most significant improvement in the BMSC + EA group. The expressions of endometrial pro-inflammatory factors and fibrosis indexes in the BMSC + EA group were lower than those in the model and BMSC groups. Further studies revealed that the expression of endometrial receptivity-related factors and the number of embryos implanted on day 8 of gestation increased in the BMSC + EA group compared with the model group and the BMSC group.

miR-340-3p-modified bone marrow mesenchymal stem cell-derived exosomes inhibit ferroptosis through METTL3-mediated m6A modification of HMOX1 to promote recovery of injured rat uterus

BACKGROUND

Ferroptosis is associated with the pathological progression of hemorrhagic injury and ischemia-reperfusion injury. According to our previous study, exosomes formed through bone marrow mesenchymal stem cells modified with miR-340-3p (MB-exos) can restore damaged endometrium. However, the involvement of ferroptosis in endometrial injury and the effect of MB-exos on ferroptosis remain elusive.

METHODS

The endometrial injury rat model was developed. Exosomes were obtained from the supernatants of bone marrow mesenchymal stromal cells (BMSCs) and miR-340/BMSCs through differential centrifugation. We conducted RNA-seq analysis on endometrial tissues obtained from the PBS and MB-exos groups. Ferroptosis was induced in endometrial stromal cells (ESCs) by treating them with erastin or RSL3, followed by treatment with B-exos or MB-exos. We assessed the endometrial total m6A modification level after injury and subsequent treatment with B-exos or MB-exos by methylation quantification assay. We performed meRIP-qPCR to analyze m6A modification-regulated endogenous mRNAs.

RESULTS

We reveal that MB-exos facilitate the injured endometrium to recover by suppressing ferroptosis in endometrial stromal cells. The injured endometrium showed significantly upregulated N6-methyladenosine (m6A) modification levels; these levels were attenuated by MB-exos through downregulation of the methylase METTL3. Intriguingly, METTL3 downregulation appears to repress ferroptosis by stabilizing HMOX1 mRNA, thereby potentially elucidating the mechanism through which MB-exos inhibit ferroptosis in ESCs. We identified YTHDF2 as a critical m6A reader protein that contributes to HMOX1 mRNA degradation. YTHDF2 facilitates HMOX1 mRNA degradation by identifying the m6A binding site in the 3'-untranslated regions of HMOX1. In a rat model, treatment with MB-exos ameliorated endometrial injury-induced fibrosis by inhibiting ferroptosis in ESCs. Moreover, METTL3 short hairpin RNA-mediated inhibition of m6A modification enhanced the inhibitory effect of MB-exos on ferroptosis in endometrial injury.

CONCLUSIONS

Thus, these observations provide new insights regarding the molecular mechanisms responsible for endometrial recovery promotion by MB-exos and highlight m6A modification-dependent ferroptosis inhibition as a prospective therapeutic target to attenuate endometrial injury.

Hypoxia-induced upregulation of hsa-miR-584-3p suppresses endometrial glandular epithelial cell function by targeting DKK-1

OBJECTIVE

To investigate the impact of hypoxia on microRNA (miRNA) expression profiles in endometrial glandular epithelial cells (EECs) and elucidate potential mechanisms underlying proliferation, migration, and invasion.

METHODS

EECs in the logarithmic growth phase were exposed to normoxic (21% oxygen) and hypoxic (1% oxygen) conditions. MiRNA expression profiles were analyzed using RNA sequencing, and differential expression of hsa-miR-584-3p was confirmed by real-time quantitative PCR (RT-qPCR). Target prediction through TargetScan identified Dickkopf-1 (DKK-1) as a target gene of hsa-miR-584-3p. The interaction between hsa-miR-584-3p and DKK-1 was validated through a double-luciferase reporter gene assay and Western blotting. Cell proliferation, migration, and invasion were assessed using the Cell Counting Kit-8 (CCK-8) assay, wound healing assay, and Transwell invasion assay, respectively.

RESULTS

Hypoxic conditions significantly upregulated the expression of hsa-miR-584-3p in EECs (P<0.001). TargetScan analysis predicted DKK-1 as a downstream target of hsa-miR-584-3p. The double-luciferase reporter gene assay confirmed the binding of hsa-miR-584-3p to the 3' untranslated region of the DKK-1 gene, leading to reduced DKK-1 protein expression (P<0.001). Functional assays demonstrated decreased proliferation and increased migration and invasion of EECs under hypoxia.

CONCLUSION

Hypoxia-induced upregulation of hsa-miR-584-3p suppresses the function of EECs by targeting DKK-1 protein activity, thereby influencing their proliferation, migration, and invasion.

Histological study of telocytes in mice intrauterine adhesion model and their positive effect on mesenchymal stem cells in vitro

Intrauterine adhesions (IUA), the main cause of secondary infertility in women, result from irreversible fibrotic repair of the endometrium due to inflammation or human factors, accompanied by disruptions in the repair function of endometrial stem cells. This significantly impacts the physical and mental health of women in their childbearing years. Telocytes (TCs), a distinctive type of interstitial cells found in various tissues and organs, play diverse repair functions due to their unique spatial structure. In this study, we conduct the inaugural exploration of the changes in TCs in IUA disease and their potential impact on the function of stem cells. Our results show that in vivo, through double immunofluorescence staining (CD34+/Vimentin+; CD34+/CD31-), as endometrial fibrosis deepens, the number of TCs gradually decreases, telopodes shorten, and the three-dimensional structure becomes disrupted in the mouse IUA mode. In vitro, TCs can promote the proliferation and cycle of bone mesenchymal stem cells (BMSCs) by promoting the Wnt/β-catenin signaling pathway, which were inhibited using XAV939. TCs can promote the migrated ability of BMSCs and contribute to the repair of stem cells during endometrial injury. In addition, TCs can inhibit the apoptosis of BMSCs through the Bcl-2/Bax pathway. In conclusion, our study demonstrates, for the first time, the resistance role of TCs in IUA disease, shedding light on their potential involvement in endometrial repair through the modulation of stem cell function.

Endometrial organoids: a reservoir of functional mitochondria for uterine repair

Background: Asherman's syndrome (AS) is a dreadful gynecological disorder of the uterus characterized by intrauterine adhesion with severe fibrotic lesions, resulting in a damaged basalis layer with infertility. Despite extensive research on overcoming AS, evidence-based effective and reproducible treatments to improve the structural and functional morphology of the AS endometrium have not been established. Methods: Endometrial organoids generated from human or mouse endometrial tissues were transplanted into the uterine cavity of a murine model of AS to evaluate their transplantable feasibility to improve the AS uterine environment. The successful engraftment of organoid was confirmed by detection of human mitochondria and cytosol (for human endometrial organoid) or enhanced green fluorescent protein signals (for mouse endometrial organoid) in the recipient endometrium. The therapeutic effects mediated by organoid transplantation were examined by the measurements of fibrotic lesions, endometrial receptivity and angiogenesis, and fertility assessment by recording the number of implantation sites and weighing the fetuses and placenta. To explore the cellular and molecular mechanisms underlying the recovery of AS endometrium, we evaluated the status of mitochondrial movement and biogenetics in organoid transplanted endometrium. Results: Successfully engrafted endometrial organoids with similar morphological and molecular features to the parental tissues dramatically repaired the AS-induced damaged endometrium, significantly reducing fibrotic lesions and increasing fertility outcomes in mice. Moreover, dysfunctional mitochondria in damaged tissues, which we propose might be a key cellular feature of the AS endometrium, was fully recovered by functional mitochondria transferred from engrafted endometrial organoids. Endometrial organoid-originating mitochondria restored excessive collagen accumulation in fibrotic lesions and shifted uterine metabolic environment to levels observed in the normal endometrium. Conclusions: Our findings suggest that endometrial organoid-originating mitochondria might be key players to mediate uterine repair resulting in fertility enhancement by recovering abrogated metabolic circumstance of the endometrium with AS. Further studies addressing the clinical applicability of endometrial organoids may aid in identifying new therapeutic strategies for infertility in patients with AS.

Apoptotic bodies of bone marrow mesenchymal stem cells inhibit endometrial stromal cell fibrosis by mediating the Wnt/β-catenin signaling pathway

Background

Intrauterine adhesions (IUAs) are a common illness of the uterine cavity. Endometrial fibrosis is the main pathological feature. In addition to a high recurrence rate, patients with severe IUAs have a low pregnancy rate. However, there are few effective treatments for IUAs. This study aims to confirm the influence of apoptotic bodies of bone marrow mesenchymal stem cells (BMSCs) on endometrial stromal cell fibrosis by mediating the Wnt/β-catenin signaling pathway and to provide new insight for the clinical treatment of IUAs.

Methods

Human endometrial stromal cells (HESCs) were used to establish an IUA cell model by treatment with TGF-β1, and a rat IUA model was established by the double injury method. Apoptosis of BMSCs was detected by TUNEL assays, and cell morphology was observed by the CM-DiI tracer. The morphology of apoptotic vacuoles and apoptotic bodies (ABs) was detected by TEM. We used Western blotting to detect the expression of histone H3.3, histone H2B, C3b, cyclin D1, C1QC, α-SMA, COL1A1, COL5A2, FN, CTGF, Wnt2b, c-MYC, CK-18 and VIM. The expression levels of α-SMA, COL1A1, COL5A2, FN and CTGF were detected by RT‒qPCR. The expression levels of α-SMA, COL1A1, FN and CTGF were detected by immunofluorescence. Immunohistochemistry was used to detect the expression of TGF-β, CK-18 and VIM. Flow cytometry, cell scratch assays, CCK-8 assays, and H & E and Masson staining were used to detect the cell cycle, cell migration, cell proliferation, and endometrial pathology, respectively.

Results

We found that ultraviolet light (UV) irradiation induced apoptosis of BMSCs and increased the production of ABs. TGF-β1 treatment can induce HESCs to form extracellular matrix (ECM), and aggravate cell fibrosis, and adding ABs or FH535, an inhibitor of the Wnt/β-catenin signaling pathway, can inhibit TGF-β1-induced HESC fibrosis. However, the inhibitory effect of ABs on TGF-β1-induced fibrosis of HESCs was attenuated by the addition of LiCl. In the Wnt/β-catenin signaling pathway, LiCl is an activator after coculture with TGF-β1. In vivo, IUA-induced narrowing of the uterine cavity was accompanied by intrauterine adhesions, increased deposition of collagen fibers, upregulation of TGF-β1, VIM, α-SMA, COL1A1 and COL5A2, and downregulation of CK-18. These changes in expression were reversed after treatment with ABs or FH535. When ABs and LiCl were added at the same time, the inhibitory effect of ABs on IUA fibrosis was weakened.

Conclusion

BMSC-derived ABs inhibit the fibrosis of HESCs by inhibiting the Wnt/β-catenin signaling pathway. These results provide a new direction for the clinical treatment of IUAs.

Three-Dimensional Printing of Polycaprolactone/Nano-Hydroxyapatite Composite Scaffolds with a Pore Size of 300/500 µm is Histocompatible and Promotes Osteogenesis Using Rabbit Cortical Bone Marrow Stem Cells

BACKGROUND Many patients have bone defects that exceed the healing size. This study aimed to construct polycaprolactone/nano-hydroxyapatite (PCL/nHA) composite scaffolds with different pore sizes and investigate the osteogenesis and histocompatibility of cortical bone mesenchymal stem cells (BMSCs-C) seeded on it after inoculation. MATERIAL AND METHODS After mixing PCL and nHA proportionally, three-dimensional (3D) printing was used to print scaffolds. Porosity, compressive strength, and elastic modulus of PCL/nHA scaffolds were tested. The proliferation of BMSCs-C cells was examined and osteogenesis, chondrogenesis, and adipogenesis were evaluated. BMSCs-C cells were inoculated into 3D printing scaffolds, and histocompatibility between BMSCs-C cells and scaffolds was observed by the cell count kit (CCK-8) assay and LIVE/DEAD staining. After inoculating BMSCs-C cells into scaffolds, alkaline phosphatase (ALP) activity and calcium content were measured. RESULTS There was no obvious difference in characteristics between the 3 PCL/nHA composite scaffolds. The porosity, compressive strength, and elastic modulus of the 300/500-μm scaffold were between those of the 300-μm and 500-μm scaffolds. With increasing pore size, the mechanical properties of the scaffold decrease. BMSCs-C cells demonstrated faster growth and better osteogenic, adipogenic, and chondrogenic differentiation; therefore, BMSCs-C cells were selected as seed cells. PCL/nHA composite scaffolds with different pore sizes had no obvious toxicity and demonstrated good biocompatibility. All scaffolds showed higher ALP activity and calcium content. CONCLUSIONS The 300/500 μm mixed pore size scaffold took into account the mechanical properties of the 300 μm scaffold and the cell culture area of the 500 μm scaffold, therefore, 300/500 μm scaffold is a better model for the construction of tissue engineering scaffolds.

Pregnancy Rates after Hysteroscopic Endometrial Polypectomy versus Endometrial Curettage Polypectomy: A Retrospective Study

Background and Objectives: A relationship between endometrial polypectomy and in vitro fertilization (IVF) pregnancy outcomes has been reported; however, only a few studies have compared polyp removal techniques and pregnancy rates. We investigated whether different polypectomy techniques with endometrial curettage and hysteroscopic polypectomy for endometrial polyps affect subsequent pregnancy outcomes. Materials and Methods: Data from 434 patients who had undergone polypectomy for suspected endometrial polyps using transvaginal ultrasonography before embryo transfer in IVF at four institutions between January 2017 and December 2020 were retrospectively analyzed. Overall, there were 157 and 277 patients in the hysteroscopic (mean age: 35.0 years) and curettage (mean age: 37.3 years) groups, respectively. Single-blastocyst transfer cases were selected from both groups and age-matched to unify background factors. Results: In the single-blastocyst transfer cases, 148 (mean age: 35.0 years) and 196 (mean age: 35.9 years) were in the hysteroscopic and curettage groups, respectively, with the 148 cases matched by age. In these cases, the pregnancy rates for the first embryo transfer were 68.2% (odds ratio (OR): 2.14) and 51.4% (OR: 1.06) in the hysteroscopic and curettage groups, respectively; the resulting OR was 2.03. The pregnancy rates after up to the second transfer were 80.4% (OR: 4.10) and 68.2% (OR: 2.14) in the hysteroscopic and curettage groups, respectively, in which the OR was 1.91. The live birth rates were 66.2% (OR: 1.956) and 53.4% (OR: 1.15) in the hysteroscopic and curettage groups, respectively, in which the odds ratio was 1.71. These results show the effectiveness of hysteroscopic endometrial polypectomy compared to polypectomy with endometrial curettage. No significant difference was found regarding the miscarriage rates between the two groups. Conclusions: Hysteroscopic endometrial polypectomy resulted in a higher pregnancy rate in subsequent embryo transfer than polypectomy with endometrial curettage. Therefore, establishing a facility where polypectomy can be performed hysteroscopically is crucial.

Treatment strategies for intrauterine adhesion: focus on the exosomes and hydrogels

Intrauterine adhesion (IUA), also referred to as Asherman Syndrome (AS), results from uterine trauma in both pregnant and nonpregnant women. The IUA damages the endometrial bottom layer, causing partial or complete occlusion of the uterine cavity. This leads to irregular menstruation, infertility, or repeated abortions. Transcervical adhesion electroreception (TCRA) is frequently used to treat IUA, which greatly lowers the prevalence of adhesions and increases pregnancy rates. Although surgery aims to disentangle the adhesive tissue, it can exacerbate the development of IUA when the degree of adhesion is severer. Therefore, it is critical to develop innovative therapeutic approaches for the prevention of IUA. Endometrial fibrosis is the essence of IUA, and studies have found that the use of different types of mesenchymal stem cells (MSCs) can reduce the risk of endometrial fibrosis and increase the possibility of pregnancy. Recent research has suggested that exosomes derived from MSCs can overcome the limitations of MSCs, such as immunogenicity and tumorigenicity risks, thereby providing new directions for IUA treatment. Moreover, the hydrogel drug delivery system can significantly ameliorate the recurrence rate of adhesions and the intrauterine pregnancy rate of patients, and its potential mechanism in the treatment of IUA has also been studied. It has been shown that the combination of two or more therapeutic schemes has broader application prospects; therefore, this article reviews the pathophysiology of IUA and current treatment strategies, focusing on exosomes combined with hydrogels in the treatment of IUA. Although the use of exosomes and hydrogels has certain challenges in treating IUA, they still provide new promising directions in this field.

Multi-Lineage Human Endometrial Organoids on Acellular Amniotic Membrane for Endometrium Regeneration

Asherman's syndrome is an endometrial regeneration disorder resulting from injury to the endometrial basal layer, causing the formation of scar tissue in the uterus and cervix. This usually leads to uterine infertility, menstrual disorders, and placental abnormalities. While stem cell therapy has shown extensive progress in repairing the damaged endometrium and preventing intrauterine adhesion, issues of low engraftment rates, rapid senescence, and the risk of tumorigenesis remain to be resolved for efficient and effective application of this technology in endometrial repair. This study addressed these challenges by developing a co-culture system to generate multi-lineage endometrial organoids (MLEOs) comprising endometrial epithelium organoids (EEOs) and endometrial mesenchymal stem cells (eMSCs). The efficacy of these MLEOs was investigated by seeding them on a biocompatible scaffold, the human acellular amniotic membrane (HAAM), to create a biological graft patch, which was subsequently transplanted into an injury model of the endometrium in rats. The results indicated that the MLEOs on the HAAM patch facilitated endometrial angiogenesis, regeneration, and improved pregnancy outcomes. The MLEOs on the HAAM patch could serve as a promising strategy for treating endometrial injury and preventing Asherman's syndrome.