Transplantation of collagen scaffold with autologous bone marrow mononuclear cells promotes functional endometrium reconstruction via downregulating ΔNp63 expression in Asherman's syndrome

Evolution of biotechnological advances and regenerative therapies for endometrial disorders: a systematic review

BACKGROUND

The establishment and maintenance of pregnancy depend on endometrial competence. Asherman syndrome (AS) and intrauterine adhesions (IUA), or endometrial atrophy (EA) and thin endometrium (TE), can either originate autonomously or arise as a result from conditions (i.e. endometritis or congenital hypoplasia), or medical interventions (e.g. surgeries, hormonal therapies, uterine curettage or radiotherapy). Affected patients may present an altered or inadequate endometrial lining that hinders embryo implantation and increases the risk of poor pregnancy outcomes and miscarriage. In humans, AS/IUA and EA/TE are mainly treated with surgeries or pharmacotherapy, however the reported efficacy of these therapeutic approaches remains unclear. Thus, novel regenerative techniques utilizing stem cells, growth factors, or tissue engineering have emerged to improve reproductive outcomes.

OBJECTIVE AND RATIONALE

This review comprehensively summarizes the methodologies and outcomes of emerging biotechnologies (cellular, acellular, and bioengineering approaches) to treat human endometrial pathologies. Regenerative therapies derived from human tissues or blood which were studied in preclinical models (in vitro and in vivo) and clinical trials are discussed.

SEARCH METHODS

A systematic search of full-text articles available in PubMed and Embase was conducted to identify original peer-reviewed studies published in English between January 2000 and September 2023. The search terms included: human, uterus, endometrium, Asherman syndrome, intrauterine adhesions, endometrial atrophy, thin endometrium, endometritis, congenital hypoplasia, curettage, radiotherapy, regenerative therapy, bioengineering, stem cells, vesicles, platelet-rich plasma, biomaterials, microfluidic, bioprinting, organoids, hydrogel, scaffold, sheet, miRNA, sildenafil, nitroglycerine, aspirin, growth hormone, progesterone, and estrogen. Preclinical and clinical studies on cellular, acellular, and bioengineering strategies to repair or regenerate the human endometrium were included. Additional studies were identified through manual searches.

OUTCOMES

From a total of 4366 records identified, 164 studies (3.8%) were included for systematic review. Due to heterogeneity in the study design and measured outcome parameters in both preclinical and clinical studies, the findings were evaluated qualitatively and quantitatively without meta-analysis. Groups using stem cell-based treatments for endometrial pathologies commonly employed mesenchymal stem cells (MSCs) derived from the human bone marrow or umbilical cord. Alternatively, acellular therapies based on platelet-rich plasma (PRP) or extracellular vesicles are gaining popularity. These are accompanied by the emergence of bioengineering strategies based on extracellular matrix (ECM)-derived hydrogels or synthetic biosimilars that sustain local delivery of cells and growth factors, reporting promising results. Combined therapies that target multiple aspects of tissue repair and regeneration remain in preclinical testing but have shown translational value. This review highlights the myriad of therapeutic material sources, administration methods, and carriers that have been tested.

WIDER IMPLICATIONS

Therapies that promote endometrial proliferation, vascular development, and tissue repair may help restore endometrial function and, ultimately, fertility. Based on the existing evidence, cost, accessibility, and availability of the therapies, we propose the development of triple-hit regenerative strategies, potentially combining high-yield MSCs (e.g. from bone marrow or umbilical cord) with acellular treatments (PRP), possibly integrated in ECM hydrogels. Advances in biotechnologies together with insights from preclinical models will pave the way for developing personalized treatment regimens for patients with infertility-causing endometrial disorders such as AS/IUA, EA/TE, and endometritis.

REGISTRATION NUMBER

https://osf.io/th8yf/.

Cytoskeletal and inter-cellular junction remodelling in endometrial organoids under oxygen-glucose deprivation: a new potential pathological mechanism for thin endometria

STUDY QUESTION

What is the pathological mechanism involved in a thin endometrium, particularly under ischaemic conditions?

SUMMARY ANSWER

Endometrial dysfunction in patients with thin endometrium primarily results from remodelling in cytoskeletons and cellular junctions of endometrial epithelial cells under ischemic conditions.

WHAT IS KNOWN ALREADY

A healthy endometrium is essential for successful embryo implantation and subsequent pregnancy; ischemic conditions in a thin endometrium compromise fertility outcomes.

STUDY DESIGN, SIZE, DURATION

We recruited 10 patients with thin endometrium and 15 patients with healthy endometrium. Doppler ultrasound and immunohistochemical results confirmed the presence of insufficient endometrial blood perfusion in patients with thin endometrium. Organoids were constructed using healthy endometrial tissue and cultured under oxygen-glucose deprivation (OGD) conditions for 24 h. The morphological, transcriptomic, protein expression, and signaling pathway changes in the OGD organoids were observed. These findings were validated in both thin endometrial tissue and healthy endometrial tissue samples.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Endometrial thickness and blood flow were measured during the late follicular phase using transvaginal Doppler ultrasound. Endometrial tissue was obtained via hysteroscopy. Fresh endometrial tissues were used for the generation and culture of human endometrial organoids. Organoids were cultured in an appropriate medium and subjected to OGD to simulate ischemic conditions. Apoptosis and cell death were assessed using Annexin-V/propidium iodide staining. Immunofluorescence analysis, RNA sequencing, western blotting, simple westerns, immunohistochemistry, and electron microscopy were conducted to evaluate cellular and molecular changes.

MAIN RESULTS AND THE ROLE OF CHANCE

Patients with thin endometrium showed significantly reduced endometrial thickness and altered blood flow patterns compared to those with healthy endometrium. Immunohistochemical staining revealed fewer CD34-positive blood vessels and glands in the thin endometrium group. Organoids cultured under OGD conditions exhibited significant morphological changes, increased apoptosis, and cell death. RNA-seq identified differentially expressed genes related to cytoskeletal remodeling and stress responses. OGD induced a strong cytoskeletal reorganization, mediated by the RhoA/ROCK signaling pathway. Additionally, electron microscopy indicated compromised epithelial integrity and abnormal cell junctions in thin endometrial tissues. Upregulation of hypoxia markers (HIF-1α and HIF-2α) and activation of the RhoA/ROCK pathway were also observed in thin endometrial tissues, suggesting ischemia and hypoxia as underlying mechanisms.

LARGE SCALE DATA

none.

LIMITATIONS AND REASONS FOR CAUTION

The study was conducted in an in vitro model, which may not fully replicate the complexity of in vivo conditions.

WIDER IMPLICATIONS OF THE FINDINGS

This research provides a new three-dimensional in vitro model of thin endometrium, as well as novel insights into the pathophysiological mechanisms of endometrial ischaemia in thin endometrium, offering potential avenues for identifying therapeutic targets for treating fertility issues related to thin endometrium.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the National Natural Science Foundation of China (81925013); National Key Research and Development Project of China (2022YFC2702500, 2021YFC2700303, 2021YFC2700601); the Capital Health Research and Development Project (SF2022-1-4092); the National Natural Science Foundation of China (82288102, 81925013, 82225019, 82192873); Special Project on Capital Clinical Diagnosis and Treatment Technology Research and Transformation Application (Z211100002921054); the Frontiers Medical Center, Tianfu Jincheng Laboratory Foundation(TFJC2023010001). The authors declare that no competing interests exist.

Transplantation of human endometrial perivascular stem cells with hydroxy saffron yellow A promotes uterine repair in rats

BACKGROUND

Intrauterine adhesions (IUAs) jeopardise uterine function in women, which is a great challenge in the clinic. Previous studies have shown that endometrial perivascular cells (En-PSCs) can improve the healing of scarred uteri and that hydroxysafflor yellow A (HSYA) promotes angiogenesis. The purpose of this study was to observe whether the combination of En-PSCs with HSYA could improve the blood supply and fertility in the rat uterus after full-thickness injury.

METHODS

En-PSCs were sorted by flow cytometry, and the effect of HSYA on the proliferation and angiogenesis of the En-PSCs was detected using CCK-8 and tube formation assays. Based on a previously reported rat IUA model, the rat uteri were sham-operated, spontaneously regenerated, or treated with collagen-loaded PBS, collagen-loaded HSYA, collagen-loaded En-PSCs, or collagen-loaded En-PSCs with HSYA, and then collected at both 30 and 90 days postsurgery. HE staining and Masson staining were used to evaluate uterine structure and collagen fibre deposition, and immunohistochemical staining for α-SMA and vWF was used to evaluate myometrial regeneration and neovascularization in each group. A fertility assay was performed to detect the recovery of pregnancy function in each group. RNA-seq was performed to determine the potential mechanism underlying En-PSCs/HSYA treatment. Immunofluorescence, tube formation assays, and Western blot were used to validate the molecular mechanism involved.

RESULTS

The transplantation of Collagen/En-PSCs/HSYA markedly promoted uterine repair in rats with full-thickness injury by reducing fibrosis, increasing endometrial thickness, regenerating myometrium, promoting angiogenesis, and facilitated live births. RNA sequencing results suggested that En-PSCs/HSYA activated the NRG1/ErbB4 signaling pathway. In vitro tube formation experiments revealed that the addition of an ErbB inhibitor diminished the tube formation ability of cocultured En-PSCs and HUVECs. Western blot results further showed that elevated levels of NRG1 and ErbB4 proteins were detected in the Collagen/En-PSCs/HSYA group compared to the Collagen/En-PSCs group. These collective results suggested that the beneficial effects of the transplantation of Collagen/En-PSCs/HSYA might be attributed to the modulation of the NRG1/ErbB4 signaling pathway.

CONCLUSIONS

The combination of En-PSCs/HSYA facilitated morphological and functional repair in rats with full-thickness uterine injury and may promote endometrial angiogenesis by regulating the NRG1/ErbB4 signaling pathway.

Ovarian function in patients with systemic lupus erythematosus: Pathogenesis, drug application and prospective therapies

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease in which multiple organs are damaged that prevails in fertile women. Currently, glucocorticoids and immunosuppressants are widely used to treat SLE patients. However, ovarian dysfunction occurs following the use of these drugs in women with SLE. Here, we summarize recent progress in terms of understanding ovarian injury, the effects of drug application and strategies to improve ovarian function in women with SLE. This review could be helpful to precisely cure SLE in women desiring to have offspring.

Validity of stem cell-loaded scaffolds to facilitate endometrial regeneration and restore fertility: a systematic review and meta-analysis

Objective

Various stem cell-loaded scaffolds have demonstrated promising endometrial regeneration and fertility restoration. This study aimed to evaluate the efficacy of stem cell-loaded scaffolds in treating uterine injury in animal models.

Methods

The PubMed, Embase, Scopus, and Web of Science databases were systematically searched. Data were extracted and analyzed using Review Manager version 5.4. Improvements in endometrial thickness, endometrial glands, fibrotic area, and number of gestational sacs/implanted embryos were compared after transplantation in the stem cell-loaded scaffolds and scaffold-only group. The standardized mean difference (SMD) and confidence interval (CI) were calculated using forest plots.

Results

Thirteen studies qualified for meta-analysis. Overall, compared to the scaffold groups, stem cell-loaded scaffolds significantly increased endometrial thickness (SMD = 1.99, 95% CI: 1.54 to 2.44, P < 0.00001; I² = 16%) and the number of endometrial glands (SMD = 1.93, 95% CI: 1.45 to 2.41, P < 0.00001; I² = 0). Moreover, stem cell-loaded scaffolds present a prominent effect on improving fibrosis area (SMD = -2.50, 95% CI: -3.07 to -1.93, P < 0.00001; I² = 36%) and fertility (SMD = 3.34, 95% CI: 1.58 to 5.09, P = 0.0002; I² = 83%). Significant heterogeneity among studies was observed, and further subgroup and sensitivity analyses identified the source of heterogeneity. Moreover, stem cell-loaded scaffolds exhibited lower inflammation levels and higher angiogenesis, and cell proliferation after transplantation.

Conclusion

The evidence indicates that stem cell-loaded scaffolds were more effective in promoting endometrial repair and restoring fertility than the scaffold-only groups. The limitations of the small sample sizes should be considered when interpreting the results. Thus, larger animal studies and clinical trials are needed for further investigation.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO, identifier CRD42024493132.

Biochemical and immunomodulatory insights of extracellular matrix from decellularized human whole cervix: recellularization andin vivoECM remodeling interplay

Extracellular matrix (ECM) rich whole organ bio-scaffolds, preserving structural integrity and essential growth factors, has potential towards regeneration and reconstruction. Women with cervical anomalies or trauma can benefit from clinical cervicovaginal repair using constructs rich in site specific ECM. In this study, complete human cervix decellularization was achieved using a modified perfusion-based stir bench top decellularization method. This was followed by physico-chemical processes including perfusion of ionic agents, enzymatic treatment and washing using detergent solutions for a duration of 10-12 d. Histopathological analysis, as well as DNA quantification confirmed the efficacy of the decellularization process. Tissue ultrastructure integrity was preserved and the same was validated via scanning electron microscopy and transmission electron microscopy studies. Biochemical analysis and structural characterizations like Fourier transform infrared, Raman spectroscopy of decellularized tissues demonstrated preservation of important proteins, crucial growth factors, collagen, and glycosaminoglycans.In vitrostudies, using THP-1 and human umbilical vein endothelial cell (HUVEC) cells, demonstrated macrophage polarization from M1 to M2 and vascular functional genes enhancement, respectively, when treated with decellularized human cervical matrix (DHCp). Crosslinked DHC scaffolds were recellularized with site specific human cervical epithelial cells and HUVEC, showing non-cytotoxic cell viability and enhanced proliferation. Furthermore, DHC scaffolds showed immunomodulatory effectsin vivoon small rodent model via upregulation of M2 macrophage genes as compared to decellularized rat cervix matrix scaffolds (DRC). DHC scaffolds underwent neo-vascularization followed by ECM remodeling with enhanced tissue integration.

Vaginal reconstruction by collagen scaffolds loaded with vaginal epithelial and smooth muscle cells in pigs

In women, a healthy and functional vagina is important for the maintenance of a good quality of life. Various factors, including congenital anomalies, cancer, trauma, infections, inflammation, or iatrogenic injuries, can lead to damage or loss of the vaginal structure, necessitating repair or replacement. Often, such reconstruction procedures involve the use of nonvaginal tissue substitutes, like segments of the large intestine or skin, which are less than ideal both anatomically and functionally. Therefore, there is an urgent need to develop new methods of vaginal reconstruction. In this study, we established a new method for isolation and expansion of vaginal epithelial and smooth muscle cells. Subsequently, collagen scaffolds designed for vaginal reconstruction were loaded with vaginal epithelial and smooth muscle cells in vitro and tested in vivo using the vaginal excision pig model. The results showed that the collagen scaffold loaded with vaginal epithelial and smooth muscle cells significantly promotes the reconstruction of the vagina compared with small intestinal submucosa (SIS) membrane or bare collagen scaffold. Notably, the reconstructed vaginal tissues exhibit remarkable similarity to their normal counterparts, encompassing not only the vaginal epithelium and smooth muscle but also the intricate networks of blood vessels and nerves. These compelling results underscore the feasibility of a tissue engineering approach in vaginal reconstruction, offering promising prospects for improving the quality of life in affected individuals.

Effect of autologous bone marrow stem cells-scaffold transplantation on the ongoing pregnancy rate in intrauterine adhesion women: a randomized, controlled trial

Intrauterine adhesion is a major cause of female reproductive disorders. Although we and others uncontrolled pilot studies showed that treatment with autologous bone marrow stem cells made a few patients with severe intrauterine adhesion obtain live birth, no large sample randomized controlled studies on this therapeutic strategy in such patients have been reported so far. To verify if the therapy of autologous bone marrow stem cells-scaffold is superior to traditional treatment in moderate to severe intrauterine adhesion patients in increasing their ongoing pregnancy rate, we conducted this randomized controlled clinical trial. Totally 195 participants with moderate to severe intrauterine adhesion were screened and 152 of them were randomly assigned in a 1:1 ratio to either group with autologous bone marrow stem cells-scaffold plus Foley balloon catheter or group with only Foley balloon catheter (control group) from February 2016 to January 2020. The per-protocol analysis included 140 participants: 72 in bone marrow stem cells-scaffold group and 68 in control group. The ongoing pregnancy occurred in 45/72 (62.5%) participants in the bone marrow stem cells-scaffold group which was significantly higher than that in the control group (28/68, 41.2%) (RR=1.52, 95%CI 1.08-2.12, P=0.012). The situation was similar in live birth rate (bone marrow stem cells-scaffold group 56.9% (41/72) vs. control group 38.2% (26/68), RR=1.49, 95%CI 1.04-2.14, P=0.027). Compared with control group, participants in bone marrow stem cells-scaffold group showed more menstrual blood volume in the 3rd and 6th cycles and maximal endometrial thickness in the 6th cycle after hysteroscopic adhesiolysis. The incidence of mild placenta accrete was increased in bone marrow stem cells-scaffold group and no severe adverse effects were observed. In conclusion, transplantation of bone marrow stem cells-scaffold into uterine cavities of the participants with moderate to severe intrauterine adhesion increased their ongoing pregnancy and live birth rates, and this therapy was relatively safe.

The effects of intraovarian injection of autologous menstrual blood-derived mesenchymal stromal cells on pregnancy outcomes in women with poor ovarian response

BACKGROUND

Assisted reproduction faces a significant obstacle in the form of poor ovarian response (POR) to controlled ovarian stimulation. To address this challenge, mesenchymal stem cell therapy has been proposed as a potential treatment for female infertility and/or restoration of ovarian function in POR women. Our previous research has demonstrated that menstrual blood-derived-mesenchymal stromal cells (MenSCs) injected into the ovaries of women with POR can increase pregnancy rates. The objective of this study was to examine whether MenSC therapy could enhance ovarian reserve parameters and pregnancy outcomes in a larger population of individuals with POR.

METHOD

This study consisted of 180 infertile individuals with POR who declined oocyte donation. Participants were divided into two groups: those who received bilateral MenSCs intraovarian injection and those who received no intervention. Our primary aim was to compare the rates of spontaneous pregnancy between the two groups, followed by an investigation of any alterations in the ovarian reserve parameters, such as serum FSH, AMH, and AFC levels, as well as the ICSI/IVF outcomes, in both groups of participants.

RESULTS

The MenSC therapy exhibited a favourable tolerability profile and did not raise any safety concerns. Following the 2-month follow-up period, women who received MenSC treatment demonstrated a significantly higher rate of spontaneous pregnancy (P < 0.005) and an improvement in anti-Müllerian hormone (AMH) levels (P = 0.0007) and antral follicle count (AFC) (P < 0.001), whereas the control group demonstrated a considerable decline in these parameters (Both P < 0.001). The MenSC therapy led to a greater number of mature oocytes and embryos among women who underwent ICSI/IVF. Our age subgroup analysis demonstrated a significant difference in the number of spontaneous pregnancies and ICSI/IVF outcomes between the treatment and control groups only among individuals below 40 years of age.

CONCLUSION

The results of our study indicate that MenSCs treatment may be a viable option for treating women experiencing POR. However, in order to be widely implemented in clinical practice, the clinical effectiveness of MenSCs therapy will need to be established through rigorous prospective randomized clinical trials.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05703308. Registered 01/26/2023, retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT05703308 . IRCT, IRCT20180619040147N4. Registered 08/01/2020.

New Solutions for Old Problems: How Reproductive Tissue Engineering Has Been Revolutionizing Reproductive Medicine

Acquired disorders and congenital defects of the male and female reproductive systems can have profound impacts on patients, causing sexual and endocrine dysfunction and infertility, as well as psychosocial consequences that affect their self-esteem, identity, sexuality, and relationships. Reproductive tissue engineering (REPROTEN) is a promising approach to restore fertility and improve the quality of life of patients with reproductive disorders by developing, replacing, or regenerating cells, tissues, and organs from the reproductive and urinary systems. In this review, we explore the latest advancements in REPROTEN techniques and their applications for addressing degenerative conditions in male and female reproductive organs. We discuss current research and clinical outcomes and highlight the potential of 3D constructs utilizing biomaterials such as scaffolds, cells, and biologically active molecules. Our review offers a comprehensive guide for researchers and clinicians, providing insights into how to reestablish reproductive tissue structure and function using innovative surgical approaches and biomaterials. We highlight the benefits of REPROTEN for patients, including preservation of fertility and hormonal production, reconstruction of uterine and cervical structures, and restoration of sexual and urinary functions. Despite significant progress, REPROTEN still faces ethical and technical challenges that need to be addressed. Our review underscores the importance of continued research in this field to advance the development of effective and safe REPROTEN approaches for patients with reproductive disorders.

Targeting CD301+ macrophages inhibits endometrial fibrosis and improves pregnancy outcome

Macrophages are a key and heterogeneous cell population involved in endometrial repair and regeneration during the menstrual cycle, but their role in the development of intrauterine adhesion (IUA) and sequential endometrial fibrosis remains unclear. Here, we reported that CD301+ macrophages were significantly increased and showed their most active interaction with profibrotic cells in the endometria of IUA patients compared with the normal endometria by single-cell RNA sequencing, bulk RNA sequencing, and experimental verification. Increasing CD301+ macrophages promoted the differentiation of endometrial stromal cells into myofibroblasts and resulted in extracellular matrix accumulation, which destroyed the physiological architecture of endometrial tissue, drove endometrial fibrosis, and ultimately led to female infertility or adverse pregnancy outcomes. Mechanistically, CD301+ macrophages secreted GAS6 to activate the AXL/NF-κB pathway, upregulating the profibrotic protein synthesis. Targeted deletion of CD301+ macrophages or inhibition of AXL by Bemcentinib blunted the pathology and improved the outcomes of pregnancy in mice, supporting the therapeutic potential of targeting CD301+ macrophages for treating endometrial fibrosis.

Etiology, Risk Factors, and Management of Asherman Syndrome

Asherman syndrome is characterized by a triad of symptoms including pain, menstrual abnormalities, and infertility and is a result of intrauterine scar tissue after instrumentation of a gravid uterus. Saline sonohysterogram is typically the most sensitive diagnostic tool; however, hysteroscopy is the criterion standard for diagnosis. Treatment includes hysteroscopic-guided lysis of adhesion, with restoration of the anatomy of the uterine cavity. Several modalities are used in an attempt to reduce the reformation of scar tissue after surgery; however, there is no consensus on the ideal method. Stem cells and platelet-rich plasma are being explored as means of regenerative therapy for the endometrium, but data remain limited. At present, most individuals can have restoration of menstrual function; however, lower pregnancy rates and obstetric complications are not uncommon. These complications are worse for patients with a higher grade of disease. Efforts are needed in standardizing classification, reducing uterine instrumentation of the gravid uterus, and referring patients to health care professionals with clinical expertise in this area.

P65 mediated UBR4 in exosomes derived from menstrual blood stromal cells to reduce endometrial fibrosis by regulating YAP Ubiquitination

BACKGROUND

Intrauterine adhesion (IUA) is a recurrent and refractory reproductive dysfunction disorder for which menstrual blood-derived stromal cells (MenSCs) might be a promising intervention. We reported that administration of MenSCs-derived exosomes (MenSCs-EXO) could achieve similar therapeutic effects to MenSCs transplantation, including alleviating endometrial fibrosis and improving fertility in IUA rats. The mass spectrometry sequencing result suggested that UBR4, a member of the proteasome family, was abundantly enriched in MenSCs-EXO. This study aimed to investigate the key role of UBR4 in MenSCs-EXO for the treatment of IUA and the specific molecular mechanism.

RESULTS

UBR4 was lowly expressed in the endometrial stromal cells (EndoSCs) of IUA patients. MenSCs-EXO treatment could restore the morphology of IUA endometrium, reduce the extent of fibrosis, and promote endometrial and vascular proliferation. Knockdown of UBR4 in MenSCs did not affect the characteristics of exosomes but attenuated the therapeutic effect of exosomes. UBR4 in MenSCs-EXO could alleviate endometrial fibrosis by boosting YAP ubiquitination degradation and promoting YAP nuclear-cytoplasmic translocation. Moreover, P65 could bind to the UBR4 promoter region to transcriptionally promote the expression level of UBR4 in MenSCs.

CONCLUSION

Our study clarified that MenSCs-EXO ameliorated endometrial fibrosis in IUA primarily by affecting YAP activity mediated through UBR4, while inflammatory signaling P65 may affect UBR4 expression in MenSCs to enhance MenSCs-EXO therapeutic effects. This revealed a novel mechanism for the treatment of IUA with MenSCs-EXO, proposing a potential option for the clinical treatment of endometrial injury.

3D bio-printed endometrial construct restores the full-thickness morphology and fertility of injured uterine endometrium

Severe damage to the uterine endometrium, which results in scar formation and endometrial dysfunction, eventually leads to infertility or pregnancy-related complications. No effective therapeutic treatment is currently available for such injuries owing to the structural complexity, internal environment, and function of the uterus. Three-dimensional (3D) bio-printing to engineer biomimetic structural constructs provides a unique opportunity for tissue regeneration. Herein, using 3D extrusion-based bioprinting (EBB), we constructed a bilayer endometrial construct (EC) based on a sodium alginate-hyaluronic acid (Alg-HA) hydrogel for functional regeneration of the endometrium. The upper layer of the 3D bio-printed EC is a monolayer of endometrial epithelial cells (EECs), while the lower layer has a grid-like microstructure loaded with endometrial stromal cells (ESCs). In a partial full-thickness uterine excision rat model, our bilayer EC not only restored the morphology and structure of the endometrial wall (including organized luminal/ glandular epithelium, stroma, vasculature and the smooth muscle layer), but also significantly improved the reproductive outcome in the surgical area after implantation (75%, 12/16, p < 0.01). Therefore, repair of the uterine endometrium using the developed 3D bio-printed bilayer EC may represent an effective regenerative treatment for severe endometrial injury. STATEMENT OF SIGNIFICANCE: Achieving structural and functional recovery of the endometrium following severe injury is still a challenge. Here, we designed a 3D bio-printed endometrial construct (EC) to mimic the native bilayer structure and cellular components of the endometrium. The bio-printed EC consists of a dense upper layer with endometrial epithelial cells and a lower layer with endometrial stromal cells. In particular, the 3D bio-printed EC significantly improved the reproductive outcome in the surgical area (75%, 12/16) compared to that of the cell-loaded non-printed group (12.5%, 2/16). This study demonstrates that a biomimetic bilayer construct can facilitate endometrial repair and regeneration. Therefore, an endometrial cells-loaded 3D-bioprinted EC is a promising therapeutic option for patients suffering from severe endometrial damage.

Autologous Human Mesenchymal Stem Cell-Based Therapy in Infertility: New Strategies and Future Perspectives

Infertility could be associated with a few factors including problems with physical and mental health, hormonal imbalances, lifestyles, and genetic factors. Given that there is a concern about the rise of infertility globally, increased focus has been given to its treatment for the last several decades. Traditional assisted reproductive technology (ART) has been the prime option for many years in solving various cases of infertility; however, it contains significant risks and does not solve the fundamental problem of infertility such as genetic disorders. Attention toward the utilization of MSCs has been widely regarded as a promising option in the development of stem-cell-based infertility treatments. This narrative review briefly presents the challenges in the current ART treatment of infertility and the various potential applications of autologous MSCs in the treatment of these reproductive diseases.

Tumor necrosis factor-α-primed mesenchymal stem cell-derived exosomes promote M2 macrophage polarization via Galectin-1 and modify intrauterine adhesion on a novel murine model

Background

Intrauterine adhesion (IUA) is a condition caused due to damage or infection of the endometrium. It is characterized by continuous inflammation and following fibrosis and dysfunction. However, the current animal IUA models have several disadvantages, including complex operation, high mortality, and many extra distractions owing to opening of the abdominal cavity to expose the uterus. Mesenchymal stem cells (MSCs), which have been used in treatment of IUA, are heterogeneous and immunosuppressive. However, their therapeutic effect is not as good as expected.

Methods

Here, we successfully built a new murine IUA model, called electric tool-scratching IUA model, and applied it in our experiments to investigate the efficacy of tumor necrosis factor-α (TNF-α) primed MSCs (T-MSCs). In the new model, we used a self-made electric tool that can cause mechanical damage to the endometrium without opening the abdominal cavity. ELISA and histological staining analysis were performed to evaluate pathological features of IUA. qRT-PCR, flow cytometry and immunofluoresence staining were performed to detect the phenotypes of macrophages. TMT proteomics quantification and western blotting assay were performed to analyze the differentially expressed proteins of MSC exosomes.

Results

Based on the new IUA model, we found TNF-α pretreatment could enhance the ability of MSCs to relieve inflammation and reduce endometrium fibrosis. Mechanistically, T-MSC promoted macrophage polarization to M2 phenotype through exosomes. Subsequently, we found the expression of Galectin-1 was increased in T-MSC exosomes. Finally, we analyzed the gene expression pattern of Galectin-1 treated macrophages and found Galectin-1 promoted macrophage polarization to M2 phenotype mainly through the Jak-STAT signaling pathway.

Conclusions

Our studies proposed an innovative mouse model and a better MSC treatment strategy for IUA.

Research progress of stem cell therapy for endometrial injury

Endometrial damage is an important factor leading to infertility and traditional conventional treatments have limited efficacy. As an emerging technology in recent years, stem cell therapy has provided new hope for the treatment of this disease. By comparing the advantages of stem cells from different sources, it is believed that menstrual blood endometrial stem cells have a good application prospect as a new source of stem cells. However, the clinical utility of stem cells is still limited by issues such as colonization rates, long-term efficacy, tumor formation, and storage and transportation. This paper summarizes the mechanism by which stem cells repair endometrial damage and clarifies the material basis of their effects from four aspects: replacement of damaged sites, paracrine effects, interaction with growth factors, and other new targets. According to the pathological characteristics and treatment requirements of intrauterine adhesion (IUA), the research work to solve the above problems from the aspects of functional bioscaffold preparation and multi-functional platform construction is also summarized. From the perspective of scaffold materials and component functions, this review will provide a reference for comprehensively optimizing the clinical application of stem cells.

Zooming in on the endometrial factor of recurrent implantation failure

Recurrent implantation failure (RIF) is a major limiting factor in the success rates of in-vitro fertilisation despite the remarkable clinical and technological advancement made at improving assisted reproductive technology. The primary purpose of the endometrium is to provide a receptive site for the implantation of the blastocyst and support its growth and subsequent development. Endometrial pathologies such as endometrial polyps, adenomyosis, Asherman's syndrome, chronic endometritis, and congenital Müllerian ducts defect negatively influence the integrity and receptivity of the endometrium, as well as the implantation of the embryo. This review highlights the implications of these endometrial pathologies and their association with RIF.

Stem Cells and Organs-on-chips: New Promising Technologies for Human Infertility Treatment

Having biological children remains an unattainable dream for most couples with reproductive failure or gonadal dysgenesis. The combination of stem cells with gene editing technology and organ-on-a-chip models provides a unique opportunity for infertile patients with impaired gametogenesis caused by congenital disorders in sex development or cancer survivors. But how will these technologies overcome human infertility? This review discusses the regenerative mechanisms, applications, and advantages of different types of stem cells for restoring gametogenesis in infertile patients, as well as major challenges that must be overcome before clinical application. The importance and limitations of in vitro generation of gametes from patient-specific human-induced pluripotent stem cells (hiPSCs) will be discussed in the context of human reproduction. The potential role of organ-on-a-chip models that can direct differentiation of hiPSC-derived primordial germ cell-like cells to gametes and other reproductive organoids is also explored. These rapidly evolving technologies provide prospects for improving fertility to individuals and couples who experience reproductive failure.

Clinical Evaluation of Autologous and Allogeneic Stem Cell Therapy for Intrauterine Adhesions: A Systematic Review and Meta-Analysis

Objective

Intrauterine adhesions (IUAs) are a major cause of female infertility. Stem cells can be used to restore endometrial function owing to their regenerative abilities. We compared the safety and efficacy of autologous and allogeneic stem cell treatments in patients with recurrent IUA after conventional therapy based on a systematic review of the related literature.

Methods

The PubMed, Embase, and Cochrane databases were systematically searched. All analysis were performed using Review Manager 5.4. We compared improvements in endometrial thickness, pregnancy rates, menstruation, and side effects after autologous and allogeneic stem cell therapy. The study was registered with PROSPERO, CRD 42022322870.

Results

Our search returned 154 reports, 10 of which met the inclusion criteria, representing 116 patients. Of these, 44 patients in two studies were treated with allogeneic stem cells and 72 patients in eight studies were treated with autologous stem cells. Improvements in endometrial thickness and pregnancy rates after intrauterine device treatment were compared between the autologous and allogeneic stem cell groups. Endometrial thickness increased more after autologous stem cell IUA treatment (mean difference, 1.68; 95% confidence interval [CI]: 1.30–2.07; P < 0.00001), and the pregnancy rate was also improved (relative risk, 1.55; 95% CI: 1.19–2.02, P < 0. 001). No obvious and serious adverse reactions were observed during stem cell therapy in either group.

Conclusions

This meta-analysis and systematic review of the results of randomized trials of autologous and allogeneic stem cell treatments for IUA suggests that autologous stem cells have a better effect in improving the endometrium thickness and pregnancy rate.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022322870.

miR-203a-3p, ABL1 and TP63 gene expression is altered in the endometrium of women with endometriosis

OBJECTIVE

Many genes and miRNAs have been shown to be associated with the pathogenesis of endometriosis. TP63 (p63) is implicated in lineage specification, proliferative potential, differentiation, cell death and survival. The ABL1 proto-oncogene encodes a cytoplasmic and nuclear protein tyrosine kinase implicated in cell differentiation, cell division, and cell adhesion. Moreover, hsa-miR-203a-3p was reported to play pivotal roles in tumor progression by targeting multiple genes, including ABL1 and TP63. The aim of this study was to investigate the expression of ABL1, TP63, and miR-203a-3p in endometriosis.

METHODS

This study included 30 women with endometriosis (stage III: n = 12 and stage IV: n = 18) and 30 age-matched controls. Total RNA extraction and cDNA synthesis were performed, and a quantitative polymerase chain reaction technique was used to determine the expression of miR-203a-3p, TP63, and ABL1.

RESULTS

TP63 and ABL1 were significantly overexpressed in stages III and IV endometriosis as compared to controls (p < .0001). Moreover, overexpression of ABL1 and TP63 was observed in stage IV compared to stage III (p = .0006 and p = .0002, respectively). Furthermore, significant increase miR-203a-3p expression has been seen in stage IV endometriosis compared to controls (p = .006). The expression of miR-203a-3p in stage III was not significant compared to stage IV and control (p = .33 and p = .43, respectively).

CONCLUSION

It is concluded that miR-203a-3p, ABL1 and TP63 gene expression is altered in the endometrium of patients with endometriosis. It is also suggested that miR-203a-3p, ABL1, and TP63 might be candidate factors for the pathogenesis of endometriosis and suggesting its therapeutic potential in endometriosis.

Therapeutic Effects and Repair Mechanism of HGF Gene-Transfected Mesenchymal Stem Cells on Injured Endometrium

There are many studies on the advantages of using mesenchymal stem cells (MSCs) that secrete various paracrine factors for repairing endometrial injury. However, the stability and effectiveness of MSCs require improvement to become a viable therapy. Hepatocyte growth factor (HGF), one of the cytokines secreted by MSCs, promotes vascular repair and mesenchymal to epithelial transformation (MET). Therefore, HGF likely promotes the repair process of the endometrium. We prepared MSCs transfected with the HGF gene to explore its repair effects and mechanism using a damaged endometrium mouse model. HGF gene-transfected MSCs were prepared by electroporation. The transfected MSCs retained their cellular characteristics and significantly increased the expression of HGF ( $P<0.01$ ). HGF gene-transfected MSCs helped damaged endometrium to recover its morphological characteristics, improved proliferation and decreased apoptosis of endometrial cells, increased the expression of endometrial vascular growth-related factors, and activated phosphorylated c-Met and AKT in the mouse endometrial damage model ( $P<0.05$ ). Compared with normal MSCs, HGF gene-transfected MSCs produced a more significant effect on damaged endometrial epithelium repair by activating the HGF/c-Met and downstream signaling pathways. Our results indicate that HGF gene-transfected MSCs provide an effective and promising tool for injured endometrium therapy.

OUP accepted manuscript

BACKGROUND

To provide the optimal milieu for implantation and fetal development, the female reproductive system must orchestrate uterine dynamics with the appropriate hormones produced by the ovaries. Mature oocytes may be fertilized in the fallopian tubes, and the resulting zygote is transported toward the uterus, where it can implant and continue developing. The cervix acts as a physical barrier to protect the fetus throughout pregnancy, and the vagina acts as a birth canal (involving uterine and cervix mechanisms) and facilitates copulation. Fertility can be compromised by pathologies that affect any of these organs or processes, and therefore, being able to accurately model them or restore their function is of paramount importance in applied and translational research. However, innate differences in human and animal model reproductive tracts, and the static nature of 2D cell/tissue culture techniques, necessitate continued research and development of dynamic and more complex in vitro platforms, ex vivo approaches and in vivo therapies to study and support reproductive biology. To meet this need, bioengineering is propelling the research on female reproduction into a new dimension through a wide range of potential applications and preclinical models, and the burgeoning number and variety of studies makes for a rapidly changing state of the field.

OBJECTIVE AND RATIONALE

This review aims to summarize the mounting evidence on bioengineering strategies, platforms and therapies currently available and under development in the context of female reproductive medicine, in order to further understand female reproductive biology and provide new options for fertility restoration. Specifically, techniques used in, or for, the uterus (endometrium and myometrium), ovary, fallopian tubes, cervix and vagina will be discussed.

SEARCH METHODS

A systematic search of full-text articles available in PubMed and Embase databases was conducted to identify relevant studies published between January 2000 and September 2021. The search terms included: bioengineering, reproduction, artificial, biomaterial, microfluidic, bioprinting, organoid, hydrogel, scaffold, uterus, endometrium, ovary, fallopian tubes, oviduct, cervix, vagina, endometriosis, adenomyosis, uterine fibroids, chlamydia, Asherman’s syndrome, intrauterine adhesions, uterine polyps, polycystic ovary syndrome and primary ovarian insufficiency. Additional studies were identified by manually searching the references of the selected articles and of complementary reviews. Eligibility criteria included original, rigorous and accessible peer-reviewed work, published in English, on female reproductive bioengineering techniques in preclinical (in vitro/in vivo/ex vivo) and/or clinical testing phases.

OUTCOMES

Out of the 10 390 records identified, 312 studies were included for systematic review. Owing to inconsistencies in the study measurements and designs, the findings were assessed qualitatively rather than by meta-analysis. Hydrogels and scaffolds were commonly applied in various bioengineering-related studies of the female reproductive tract. Emerging technologies, such as organoids and bioprinting, offered personalized diagnoses and alternative treatment options, respectively. Promising microfluidic systems combining various bioengineering approaches have also shown translational value.

WIDER IMPLICATIONS

The complexity of the molecular, endocrine and tissue-level interactions regulating female reproduction present challenges for bioengineering approaches to replace female reproductive organs. However, interdisciplinary work is providing valuable insight into the physicochemical properties necessary for reproductive biological processes to occur. Defining the landscape of reproductive bioengineering technologies currently available and under development for women can provide alternative models for toxicology/drug testing, ex vivo fertility options, clinical therapies and a basis for future organ regeneration studies.

The Latest Developments in Immunomodulation of Mesenchymal Stem Cells in the Treatment of Intrauterine Adhesions, Both Allogeneic and Autologous

Intrauterine adhesion (IUA) is an endometrial fibrosis disease caused by repeated operations of the uterus and is a common cause of female infertility. In recent years, treatment using mesenchymal stem cells (MSCs) has been proposed by many researchers and is now widely used in clinics because of the low immunogenicity of MSCs. It is believed that allogeneic MSCs can be used to treat IUA because MSCs express only low levels of MHC class I molecules and no MHC class II or co-stimulatory molecules. However, many scholars still believe that the use of allogeneic MSCs to treat IUA may lead to immune rejection. Compared with allogeneic MSCs, autologous MSCs are safer, more ethical, and can better adapt to the body. Here, we review recently published articles on the immunomodulation of allogeneic and autologous MSCs in IUA therapy, with the aim of proving that the use of autologous MSCs can reduce the possibility of immune rejection in the treatment of IUAs.

Mesenchymal stem cells therapy: A promising method for the treatment of uterine scars and premature ovarian failure

Both intrauterine adhesions (IUA) and premature ovarian failure (POF) have plagued women all over the world for a long time. It is well known that all invasive operations involving the uterus can disrupt its structural and functional integrity to a varying degree, which inevitably lead to abnormal scar formation, such as IUA, also known as Asherman's syndrome with symptoms like hypomenorrhea or infertility. Another reproductive disorder that causes infertility is primary ovarian insufficiency (POI) or POF, which is a degenerative phenomenon in the ovary among women under the age of 40. In recent years, various types of stem cells, especially mesenchymal stem cells (MSCs) have been widely used in reproductive medicine due to their properties, such as immunoregulation, anti-inflammation, angiogenesis, anti-apoptosis, and trophicity. However, the extensive clinical application of cell therapy is impeded by their safety, cost, and manufacturing. In this review, we sought to summarize the recent advances in using different types of MSCs in treating uterine scars and POF. We also describe several biological pathways and molecules involved in animal studies and clinical application; extracellular vesicles secreted by MSCs may be a promising attractive tool to ensure the treatment of infertility by restoring normal reproductive function.

Bioengineered endometrial hydrogels with growth factors promote tissue regeneration and restore fertility in murine models

Extracellular matrix (ECM) hydrogels obtained from decellularized tissues are promising biocompatible materials for tissue regeneration. These biomaterials may provide important options for endometrial pathologies such as Asherman's syndrome and endometrial atrophy, which lack effective therapies thus far. First, we performed a proteomic analysis of a decellularized endometrial porcine hydrogel (EndoECM) to describe the specific role of ECM proteins related to regenerative processes. Furthermore, we investigated the ability of a bioengineered system-EndoECM alone or supplemented with growth factors (GFs)-to repair the endometrium in a murine model of endometrial damage. For this model, the uterine horns of female C57BL/6 mice were first injected with 70% ethanol, then four days later, they were treated with: saline (negative control); biotin-labeled EndoECM; or biotin-labeled EndoECM plus platelet-derived GF, basic fibroblast GF, and insulin-like GF 1 (EndoECM+GF). Endometrial regeneration and fertility restoration were evaluated by assessing the number of glands, endometrial area, cell proliferation, neaoangiogenesis, reduction of collagen deposition, and fertility restoration. Interestingly, regenerative effects such as an increased number of endometrial glands, increased area, high cell proliferative index, development of new blood vessels, reduction of collagen deposition, and higher pregnancy rate occurred in mice treated with EndoECM+GF. Thus, a bioengineered system based on EndoECM hydrogel supplemented with GFs may be promising for the clinical treatment of endometrial conditions such as Asherman's syndrome and endometrial atrophy. STATEMENT OF SIGNIFICANCE: In the last years, the bioengineering field has developed new and promising approaches to regenerate tissues or replace damaged and diseased tissues. Bioengineered hydrogels offer an ideal option because these materials can be used not only as treatments but also as carriers of drugs and other therapeutics. The present work demonstrates for the first time how hydrogels derived from pig endometrium loaded with growth factors could treat uterine pathologies in a mouse model of endometrial damage. These findings provide scientific evidence about bioengineered hydrogels based on tissue-specific extracellular matrix offering new options to treat human infertility from endometrial causes such as Asherman's syndrome or endometrial atrophy.

Stem cell-based therapy for ameliorating intrauterine adhesion and endometrium injury

Intrauterine adhesion refers to endometrial repair disorders which are usually caused by uterine injury and may lead to a series of complications such as abnormal menstrual bleeding, recurrent abortion and secondary infertility. At present, therapeutic approaches to intrauterine adhesion are limited due to the lack of effective methods to promote regeneration following severe endometrial injury. Therefore, to develop new methods to prevent endometrial injury and intrauterine adhesion has become an urgent need. For severely damaged endometrium, the loss of stem cells in the endometrium may affect its regeneration. This article aimed to discuss the characteristics of various stem cells and their applications for uterine tissue regeneration.

A Simulation Study on the Growth of Oviduct Mucosa Cells in the Uterine Cavity Microenvironment

Objective

The growth of oviduct mucosa in the uterine cavity was observed by co-culture of oviduct mucosa cells and endometrial cells in different proportions to study the possibility and function of the growth of oviduct mucosa in the uterine cavity.

Methods

The extracted cells were identified by immunofluorescence with cytokeratins 19 (CK19) and vimentin. A Cell Counting Kit-8 (CCK8) experiment, cell decidualization induction, and HE staining were performed after the co-culture of two kinds of cells in different proportions.

Results

1) The cells could grow normally when the two cells were co-cultured indirectly. 2) A CCK8 test of oviduct mucosa cells showed that the growth rate of each group was similar after the indirect co-culture of two kinds of cells in different proportions, which was in line with the growth law of normal cells. 3) Immunofluorescence identification of the cells showed that most of the two kinds of cells in the second passage were CK19 positive and were epithelial cells, while most of the cells in the fifth passage expressed positive vimentin antibody and were stroma cells. 4) After cell decidualization induction, the cell morphology of each group showed deciduation-like changes. 5) After decidualization, the cell morphology of each group was similar after HE staining.

Conclusion

Oviduct mucosa cells can grow normally in the uterine environment. In the uterine environment with different degrees of endometrial loss, the growth rate of oviduct mucosa cells is not inhibited. Its morphology does not change, and it can undergo decidualization in vitro.

Application of Bioactive Hydrogels for Functional Treatment of Intrauterine Adhesion

Intrauterine adhesion (IUA) is a common endometrial disease and one of the main causes of infertility in women of childbearing age. Current treatment strategies, such as hysteroscopic adhesion resection, hysteroscopic transcervical resection of adhesion (TCRA), the use of local hormone drugs, and anti-adhesion scaffold implantation, do not provide a satisfactory pregnancy outcome for moderate-severe IUA, which presents a great challenge in reproductive medicine. With the development of material engineering, various bioactive and functional hydrogels have been developed using natural and synthetic biomaterials. These hydrogels are not only used as barely physical barriers but are also designed as vectors of hormone drugs, growth factors, and stem cells. These characteristics give bioactive hydrogels potentially important roles in the prevention and treatment of IUA. However, there is still no systematic review or consensus on the current advances and future research direction in this field. Herein, we review recent advances in bioactive hydrogels as physical anti-adhesion barriers, in situ drug delivery systems, and 3D cell delivery and culture systems for seeded cells in IUA treatment. In addition, current limitations and future perspectives are presented for further research guidance, which may provide a comprehensive understanding of the application of bioactive hydrogels in intrauterine adhesion treatment.

Human Acellular Amniotic Matrix with Previously Seeded Umbilical Cord Mesenchymal Stem Cells Restores Endometrial Function in a Rat Model of Injury

Background

Abnormal endometrial repair after injury results in the formation of intrauterine adhesions (IUA) and a thin endometrium, which are key causes for implantation failure and infertility. Stem cell transplantation offers a potential alternative for some cases of severe Asherman's syndrome that cannot be treated with surgery or hormonal therapy. Umbilical cord-derived mesenchymal stem cells (UCMSCs) have been reported to repair the damaged endometrium. However, there is no report on the effects of UCMSCs previously seeded on human acellular amniotic matrix (AAM) on endometrial injury.

Methods

Absolute ethanol was injected into rat uteri to damage the endometrium. UCMSCs previously seeded on AAM were surgically transplanted. Using a variety of methods, the treatment response was assessed by endometrial thickness, endometrial biomarker expression, endometrial receptivity, cell proliferation, and inflammatory factors.

Results

Endometrial thickness was markedly improved after UCMSC-AAM transplantation. The expression of endometrial biomarkers, namely, vimentin, cytokeratin, and integrin β3, in treated rats increased compared with untreated rats. In the UCMSC-AAM group, the VEGF expression decreased, whereas that of MMP9 increased compared with the injury group. Moreover, in the AAM group, the MMP9 expression increased. The expression of proinflammatory factors (IL-2, TNFα, and IFN-γ) in the UCMSC-AAM group decreased compared with the untreated group, whereas the expression of anti-inflammatory factors (IL-4, IL-10) increased significantly.

Conclusions

UCMSC transplantation using AAM as the carrier can be applied to treat endometrial injury in rats. The successful preparation of lyophilized AAM provides the possibility of secondary infectious disease screening and amniotic matrix quality detection, followed by retrospective analysis. The UCMSC-AAM complex may promote the better application of UCMSCs on the treatment of injured endometrium.

Efficacy and safety of autologous platelet-rich fibrin for the treatment of infertility with intrauterine adhesions

AIM

To evaluate the efficacy and safety of autologous platelet-rich fibrin (PRF) for the treatment of infertility with intrauterine adhesions.

METHODS

Forty patients who suffered from infertility with intrauterine adhesions (IUAs) were enrolled in this prospective trial from October 2018 to December 2019. They were randomly divided into a PRF group and a control group. Both groups underwent transcervical resection of adhesions (TCRA) during the follicular phase. PRF group: PRF prepared from autologous venous blood was placed in the uterine cavity after TCRA and after the first menstrual re-fluid; control group: no PRF insertion. After the second menstrual re-fluid, both groups underwent hysteroscopy to reevaluate adhesion severity. Pregnancy rate, intrauterine adhesion score, menstrual volume and duration, and endometrial thickness were assessed and adverse events were recorded.

RESULTS

(1) PRF group pregnancy rate was significantly higher than the control group (55.0% vs. 20.0%). Mean follow-up time was (17.63 ± 2.33) months. All patients fell pregnant naturally. Four (PRF) and one (control) patients delivered live births without placental complications. (2) Intrauterine adhesion scores decreased compared with treatment-before. (3) In the pictorial blood loss assessment chart, score and menstrual duration during the 3rd menstrual cycle showed significant improvements for both groups. (4) Endometrial thickness also showed an increasing trend, and subendometrial bloodflow improved. (5) No treatment-related serious adverse events were noted.

CONCLUSION

Placing PRF into the uterine cavity of infertility patients with IUAs following TCRA is a safe and effective therapeutic method.

Uterine Tissue Engineering: Where We Stand and the Challenges Ahead

Tissue engineering is an innovative approach to develop allogeneic tissues and organs. The uterus is a very sensitive and complex organ, which requires refined techniques to properly regenerate and even, to rebuild itself. Many therapies were developed in 20th century to solve reproductive issues related to uterus failure and, more recently, tissue engineering techniques provided a significant evolution in this issue. Herein we aim to provide a broad overview and highlights of the general concepts involved in bioengineering to reconstruct the uterus and its tissues, focusing on strategies for tissue repair, production of uterine scaffolds, biomaterials and reproductive animal models, highlighting the most recent and effective tissue engineering protocols in literature and their application in regenerative medicine. In addition, we provide a discussion about what was achieved in uterine tissue engineering, the main limitations, the challenges to overcome and future perspectives in this research field.

Hydrogel, a novel therapeutic and delivery strategy, in the treatment of intrauterine adhesions

Intrauterine adhesions (IUAs) are caused by damage to the underlying lining of the endometrium. They' re related to disorder of endometrial repair. In recent years, hydrogels with controllable biological activity have been widely used for treating IUAs. They encapsulate estrogen, cytokines, cells, or exosomes, forming a delivery system to release therapeutic components for the treatment of IUAs. In addition, the hydrogel acting as a barrier can be degraded in the body automatically, reducing the risk of infection caused by secondary surgeries. In this review, we summarize the recent progress of hydrogels and their application in IUAs as both a novel alternative therapeutic and an artificial delivery strategy.

Unresponsive thin endometrium caused by Asherman syndrome treated with umbilical cord mesenchymal stem cells on collagen scaffolds: a pilot study

Background

Unresponsive thin endometrium caused by Asherman syndrome (AS) is the major cause of uterine infertility. However, current therapies are ineffective. This study is to evaluate the effect of transplantation with collagen scaffold/umbilical cord mesenchymal stem cells (CS/UC-MSCs) on this refractory disease.

Methods

Eighteen infertile women with unresponsive thin endometrium, whose frozen–thawed embryo transfers (FETs) were cancelled due to reduced endometrial thickness (ET ≤ 5.5 mm), were enrolled in this before and after self-control prospective study. Hysteroscopic examination was performed to confirm no intrauterine adhesions, then twenty million UC-MSCs loaded onto a CS were transplanted into the uterine cavity in two consecutive menstrual cycles. Then uterine cavity was assessed through hysteroscopy after two transplants. FETs were performed in the following cycle. Pregnancy outcomes were followed up. Endometrial thickness, uterine receptivity and endometrial angiogenesis, proliferation and hormone response were compared before and after treatment.

Results

Sixteen patients completed the study. No treatment-related serious adverse events occurred. Three months after transplantation, the average ET increased from 4.08 ± 0.26 mm to 5.87 ± 0.77 mm (P < 0.001). Three of 15 patients after FET got pregnant, of whom 2 gave birth successfully and 1 had a miscarriage at 25 weeks’ gestation. One of 2 patients without FET had a natural pregnancy and gave birth normally after transplantation. Immunohistochemical analysis showed increased micro-vessel density, upregulated expression of Ki67, estrogen receptor alpha, and progesterone receptor, indicating an improvement in endometrial angiogenesis, proliferation, and response to hormones.

Conclusion

CS/UC-MSCs is a promising and potential approach for treating women with unresponsive thin endometrium caused by AS.

Trial registration

ClinicalTrials.gov NCT03724617. Registered on 26 October 2018—prospectively registered, https://register.clinicaltrials.gov/

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02499-z.

circPTPN12/miR-21-5 p/∆Np63α pathway contributes to human endometrial fibrosis

Emerging evidence demonstrates the important role of circular RNAs (circRNAs) in regulating pathological processes in various diseases including organ fibrosis. Endometrium fibrosis is the leading cause of uterine infertility, but the role of circRNAs in its pathogenesis is largely unknown. Here, we provide the evidence that upregulation of circPTPN12 in endometrial epithelial cells (EECs) of fibrotic endometrium functions as endogenous sponge of miR-21-5 p to inhibit miR-21-5 p expression and activity, which in turn results in upregulation of ΔNp63α to induce the epithelial mesenchymal transition (EMT) of EECs (EEC-EMT). In a mouse model of endometrium fibrosis, circPTPN12 appears to be a cofactor of driving EEC-EMT and administration of miR-21-5 p could reverse this process and improve endometrial fibrosis. Our findings revealed that the dysfunction of circPTPN12/miR-21-5 p/∆Np63α pathway contributed to the pathogenesis of endometrial fibrosis.

Stem Cell-Based Therapy for Asherman Syndrome: Promises and Challenges

Asherman syndrome (AS) has an adverse effect on reproductive health and fertility by affecting endometrial regeneration. Stem cell-based therapies hold promise for future use in activating non-functional endometrium and reconstructing the endometrium in vivo. It has been postulated that various endometrial stem cells (EnSCs) are responsible for endometrial regeneration. Numerous studies have focused on bone marrow-derived stem cells (BMDSCs), which may provide new ideas for repairing endometrial lesions and reconstructing the endometrium. Other sources of stem cells, such as menstrual blood, umbilical cord, and amniotic membrane, have also attracted much attention as candidates for transplantation in AS. This review discusses the features and specific biomarkers among four types of resident endometrial stem cells, applications of four different sources of exogenous stem cells in AS, and development of stem cell therapy using biomaterials and exosomes.

Mesenchymal Stem Cells in Preclinical Infertility Cytotherapy: A Retrospective Review

Infertility is a global reproductive disorder which is caused by a variety of complex diseases. Infertility affects the individual, family, and community through physical, psychological, social and economic consequences. The results from recent preclinical studies regarding stem cell-based therapies are promising. Stem cell-based therapies cast a new hope for infertility treatment as a replacement or regeneration strategy. The main features and application prospects of mesenchymal stem cells in the future of infertility should be understood by clinicians. Mesenchymal stem cells (MSCs) are multipotent stem cells with abundant source, active proliferation, and multidirectional differentiation potential. MSCs play a role through cell homing, secretion of active factors, and participation in immune regulation. Another advantage is that, compared with embryonic stem cells, there are fewer ethical factors involved in the application of MSCs. However, a number of questions remain to be answered prior to safe and effective clinical application. In this review, we summarized the recent status of MSCs in the application of the diseases related to or may cause to infertility and suggest a possible direction for future cytotherapy to infertility.

Expression and potential role of CXCL5 in the pathogenesis of intrauterine adhesions

Objective

C-X-C motif chemokine ligand 5 (CXCL5), a member of the chemokine family, is associated with remodeling of connective tissues. However, its role in formation of intrauterine adhesions (IUA) remains unclear. We aimed to investigate the expression and mechanism underlying the role of CXCL5 in IUA.

Methods

Expression of CXCL5 in IUA was detected by immunohistochemistry in a rat model of IUA and by real-time PCR and western blotting in patients with IUA. The protein levels of matrix metalloproteinase 9 (MMP9) and transcription factor p65 in human endometrial cells were assessed by western blotting after CXCL5 overexpression.

Results

Protein expression of CXCL5 was significantly decreased in the endometria of IUA rats compared with that of control and sham-operated rats. Real-time PCR and western blotting in patients with IUA showed similar results to those from the rat model. After overexpression, CXCL5 significantly upregulated expression of MMP9 and slightly upregulated expression of p65 in human endometrial cells.

Conclusions

CXCL5 plays an important role in IUA formation after endometrial injury. We propose a molecular mechanism to explain formation of IUA, including downregulation of MMP9 by low CXCL5 expression. These findings provide valuable information for the prevention and targeted therapy of IUA.

Cell-based endometrial regeneration: current status and future perspectives

Endometrial-related disorders including Asherman's syndrome, thin endometrium, pelvic organ prolapse, and cesarean scar pregnancies can be accompanied by different symptoms such as amenorrhea, infertility, abnormal placental implantation and recurrent miscarriage. Different methods have been introduced to overcome these problems such as surgery and hormonal therapy but none of them has shown promising outcomes. On the other hand, the development of novel regenerative therapeutic strategies has opened new avenues for the treatment of endometrial-related deficiencies. In this regard, different types of scaffolds, acellular matrices and also cell therapy with adult or stem cells have been investigated for the treatment of endometrial-related deficiencies. In this paper, we review the current status of cell-based endometrium regeneration using scaffold dependent and scaffold-free methods and future perspectives in this field. Moreover, we discuss the endometrial diseases that can be candidates for cell-based treatments. Also, the cells with the potential for endometrial regeneration are explained.

Endometrial membrane organoids from human embryonic stem cell combined with the 3D Matrigel for endometrium regeneration in asherman syndrome

Asherman's syndrome (AS), a leading cause of uterine infertility worldwide, is characterized by scarring of the uterine surfaces lacking endometrial epithelial cells, which prevents endometrial regeneration. Current research on cell therapy for AS focuses on mesenchymal and adult stem cells from the endometrium. However, insufficient number, lack of purity, and rapid senescence of endometrial epithelial progenitor cells (EEPCs) during experimental processes restrict their use in cell therapies. In this study, we induced human embryonic stem cells-9 (H9-ESC) into EEPCs by optimizing the induction factors from the definitive endoderm. EEPCs, which act as endometrial epithelial cells, accompanied by human endometrial stromal cells provide a niche environment for the development of endometrial membrane organoids (EMOs) in an in vitro 3D culture model. To investigate the function of EMOs, we transplanted tissue-engineered constructs with EMOs into an in vivo rat AS model. The implantation of EMOs into the damaged endometrium facilitates endometrial regeneration and angiogenesis. Implanting EMOs developed from human embryonic stem cells into the endometrium might prove useful for "endometrial re-engineering" in the treatment of Asherman's syndrome.

Bioengineering of the Uterus

Impairment of uterine structure and function causes infertility, pregnancy loss, and perinatal complications in humans. Some types of uterine impairments such as Asherman’s syndrome, also known as uterine synechiae, can be treated medically and surgically in a standard clinical setting, but absolute defects of uterine function or structure cannot be cured by conventional approaches. To overcome such hurdles, partial or whole regeneration and reconstruction of the uterus have recently emerged as new therapeutic strategies. Transplantation of the whole uterus into patients with uterine agenesis results in the successful birth of children. However, it remains an experimental treatment with numerous difficulties such as the need for continuous and long-term use of immunosuppressive drugs until a live birth is achieved. Thus, the generation of the uterus by tissue engineering technologies has become an alternative but indispensable therapeutic strategy to treat patients without a functional or well-structured uterus. For the past 20 years, the bioengineering of the uterus has been studied intensively in animal models, providing the basis for clinical applications. A variety of templates and scaffolds made from natural biomaterials, synthetic materials, or decellularized matrices have been characterized to efficiently generate the uterus in a manner similar to the bioengineering of other organs and tissues. The goal of this review is to provide a comprehensive overview and perspectives of uterine bioengineering focusing on the type, preparation, and characteristics of the currently available scaffolds.

Repair abilities of mouse autologous adipose-derived stem cells and ShakeGel™3D complex local injection with intrauterine adhesion by BMP7-Smad5 signaling pathway activation

BACKGROUND

The objective was to explore the therapeutic effect of autologous adipose-derived stem cells (ADSCs) combined with ShakeGel™3D transplantation to activate the BMP7-Smad5 signaling pathway to treat intrauterine adhesions (IUA).

METHODS

Autologous ADSCs were isolated and then merged with ShakeGel™3D. The IUA model was established by mechanical injury. The third generation of autologous ADSCs was injected directly into the uterus in combination with ShakeGel™3D. After 7 days of treatment, endometrial morphology, number of endometrial glands, endometrial fibrosis area, and fibrosis biomarker analysis by RT-PCR and IHC were examined. BMP7 and phosphorylation of Smad5 were also detected, and the recovery of infertility function in treated mice was evaluated.

RESULTS

Fluorescence-activated cell sorting (FACS) showed that autologous ADSCs expressed CD105 (99.1%), CD29 (99.6%), and CD73 (98.9%). Autologous ADSCs could still maintain a good growth state in ShakeGel™3D. Histological examination revealed that the number of endometrial glands increased significantly, and the area of fibrosis decreased. At the same time, the expression of BMP7 and Smad5 in the ADSCs + Gel group was significantly upregulated, and the final reproductive function of this group was partly recovered.

CONCLUSIONS

Autologous ADSCs can be used in combination with ShakeGel™3D to maintain functionality and create a viable three-dimensional growth environment. The combined transplantation of autologous ADSCs and ShakeGel™3D promotes the recovery of damaged endometrial tissue by increasing BMP7-Smad5 signal transduction, resulting in endometrium thickening, increased number of glands, and decreased fibrosis, leading to restoration of partial fertility.

Recent developments in bio-scaffold materials as delivery strategies for therapeutics for endometrium regeneration

Intrauterine adhesions (IUAs) refer to the repair disorder after endometrial injury and may lead to uterine infertility, recurrent miscarriage, abnormal menstrual bleeding, and other obstetric complications. It is a pressing public health issue among women of childbearing age. Presently, there are limited clinical treatments for IUA, and there is no sufficient evidence that these treatment modalities can effectively promote regeneration after severe endometrial injury or improve pregnancy outcome. The inhibitory pathological micro-environment is the main factor hindering the repair of endometrial damaged tissues. To address this, tissue engineering and regenerative medicine have been achieving promising developments. Particularly, biomaterials have been used to load stem cells or therapeutic factors or construct an in situ delivery system as a treatment strategy for endometrial injury repair. This article comprehensively discusses the characteristics of various bio-scaffold materials and their application as stem cell or therapeutic factor delivery systems constructed for uterine tissue regeneration.

Clinical Efficacy and Safety of Stem Cell-Based Therapy in Treating Asherman Syndrome: A System Review and Meta-Analysis

Asherman's Syndrome (AS) is an uncommon, acquired, and refractory gynecological disorder. Current treatment was still limited, and stem cell-based therapy has been proposed as a novel strategy for management of AS. Here, we conducted a meta-analysis of self-controlled clinical trials to assess the effectiveness and safety of stem cell-based therapy in Asherman syndrome patients who have failed in conventional treatment. We systematically searched PubMed, Embase, Cochrane, and Web of Science database (published up to October 3, 2020). Our main evaluation outcomes were menses improvement, endometrial thickness changes, pregnancy outcome, and side effects. All analyses were performed by using RevMan5.4 software. 427 studies were identified, eight of which were eligible and included in our analysis. Stem cell combined hormone therapy achieved a higher likelihood of improving menstruation (risk ratio [RR] 22.43, 95% CI: 8.03 to 62.68, P < 0.00001), an enhancement of pregnancy outcome (risk ratio [RR] 11.1, 95% CI: 3.58 to 34.38, P < 0.0001), and a mean increase of 3-month endometrial thickness (standardized mean difference [SMD] 2.43, 95% CI: 1.72 to 3.13, P < 0.00001). Subgroup analysis also indicated that 6-month and 9-month endometrial thickness increased significantly with the stem cell-based treatment. Moreover, no obvious and severe adverse reactions were observed during the process of stem cell therapy. There were 3 patients (3.57%) reported with lost appetite, mild gastritis, vomiting, or abdominal cramps, whereas, these symptoms relieved subsequently. This meta-analysis systematically reviewed and synthesized the outcomes of stem cell-based therapy in treating Asherman syndrome, which suggest that stem cell and hormone combination therapy was safe and more effective in improving menstruation duration, pregnancy outcome, and endometrial thickness. However, further trials with large sample sizes are needed to establish more solid evidence for administrating this therapy in clinic.

Similar Repair Effects of Human Placenta, Bone Marrow Mesenchymal Stem Cells, and Their Exosomes for Damaged SVOG Ovarian Granulosa Cells

Background

This study is aimed at investigating the repairing effect of mesenchymal stem cells and their exosomes from different sources on ovarian granulosa cells damaged by chemotherapy drugs—phosphoramide mustard (PM).

Methods

In this study, we choose bone marrow mesenchymal stem cells (BMSCs) and human placental mesenchymal stem cells (HPMSCs) for research. Then, they were cocultured with human ovarian granulosa cells (SVOG) injured by phosphoramide mustard (PM), respectively. β-Galactosidase staining, flow cytometry, and Western blot were used to detect the changes in the senescence and apoptosis of SVOG cells before and after their coculture with the above two types of MSCs. Subsequently, exosomes from these two types of MSCs were extracted and added to the culture medium of SVOG cells after PM injury to test whether these two types of exosomes played a role similar to that of MSCs in repairing damaged SVOG cells.

Results

PM treatment-induced apoptotic SVOG cells were significantly decreased after HPMSCs and BMSCs as compared with control group. After coculturing with these two types of MSCs, PM-treated SVOG cells showed significantly reduced senescence and apoptosis proportions as well as cleaved-Caspase 3 expression, and HPMSCs played a slightly stronger role than BMSCs in repairing SVOG cells in terms of the above three indicators. In addition, the ratios of senescent and apoptotic SVOG cells were also significantly reduced by the two types of exosomes, which played a role similar to that of MSCs in repairing cell damages.

Conclusions

The results indicated that BMSCs, HPMSCs, and their exosomes all exerted a certain repair effect on SVOG cells damaged by PM, and consistent repair effect was observed between exosomes and MSCs. The repair effect of exosomes secreted from BMSCs and HPMSCs on the SVOG cells was studied for the first time, and the results fully demonstrated that exosomes are the key carriers for MSCs to play their role.

Mesenchymal Stem Cells as a Bio Organ for Treatment of Female Infertility

Female infertility is a global medical condition that can be caused by various disorders of the reproductive system, including premature ovarian failure (POF), polycystic ovary syndrome (PCOS), endometriosis, Asherman syndrome, and preeclampsia. It affects the quality of life of both patients and couples. Mesenchymal stem cells (MSCs) have received increasing attention as a potential cell-based therapy, with several advantages over other cell sources, including greater abundance, fewer ethical considerations, and high capacity for self-renewal and differentiation. Clinical researchers have examined the therapeutic use of MSCs in female infertility. In this review, we discuss recent studies on the use of MSCs in various reproductive disorders that lead to infertility. We also describe the role of microRNAs (miRNAs) and exosomal miRNAs in controlling MSC gene expression and driving MSC therapeutic outcomes. The clinical application of MSCs holds great promise for the treatment of infertility or ovarian insufficiency, and to improve reproductive health for a significant number of women worldwide.

Comparison of the regenerative effects of bone marrow/adipose-derived stem cells in the Asherman model following local or systemic administration

PURPOSE

Cell therapy is a promising strategy for the treatment of Asherman's syndrome (AS), but the origin of these cells and injection route influence the therapeutic effect and complications of cell therapy. Herein, we compared the effects of systemic or local intrauterine injection of bone marrow or adipose-derived mesenchymal stem cells (BMSCs/AMSCs) on the endometrium in a rat model of AS.

METHODS

After induction of AS in adult Wistar rats, the CM-Dil-positive BMSCs or AMSCs were injected either locally or intravenously. After 3 weeks, endometrial thickness, collagen deposition, cell migration, and VEGF expression were evaluated using histochemistry/immunofluorescence studies.

RESULTS

In all stem cell-treated groups, an ameliorative effect on the damaged endometrium was noted. Collagen deposition diminished in both groups (IV and local injection) compared to the AS model. In rats injected locally with MSC, fibrosis decreased compared to the other groups. Moreover, endometrial thickness increased in the groups that received local injection of BMSCs and AMSCs more than the IV-transplanted AMSCs group. Immunofluorescent staining demonstrated that although the systemic transplantation of BMSCs was more effective than the other groups on VEGF expression, it led to the lowest number of CM-Dil+ stem cells in the damaged endometrium.

CONCLUSION

Stem cell transplantation may reconstruct the damaged endometrium, but it is recommended to select the most effective stem cells and injection route. Because the removal of the fibrosis and the replacement of the epithelia cells is an effective therapeutic strategy for AS, in this study, we conclude that the local injection of AMSCs is more appropriate than BMSCs to treat AS.

ΔNp63α-induced DUSP4/GSK3β/SNAI1 pathway in epithelial cells drives endometrial fibrosis

Epithelial homeostasis plays an essential role in maintaining endometrial function. But the epithelial role in endometrial fibrosis has been less studied. Previously, we showed that ectopic expression of ΔNp63α is associated with fibrosis process and epithelial dysfunction in endometria of patients with intrauterine adhesions (IUAs). Since ΔNp63α is profoundly involved in maintaining the epithelial homeostasis, we hereby focused on its roles in regulating the function and phenotype of endometrial epithelial cells (EECs) in context of endometrial fibrosis. We identified a typical type 2 epithelial-to-mesenchymal transition (EMT) in EECs from IUA patients and this process was induced by the forced expression of ΔNp63α in EECs. In transcriptomic analysis, we found that diverse signaling pathways regulated by ΔNp63α were involved in pro-EMT. We demonstrated that the DUSP4/GSK-3β/SNAI1 pathway was critical in transducing the pro-EMT signals initiated by ΔNp63α, while bFGF reversed ΔNp63α-induced EMT and endometrial fibrosis both in vitro and in vivo by blocking DUSP4/GSK3β/SNAI1 pathway. Taken together, our findings are important to understand the molecular mechanisms of endometrial fibrosis and to provide potential therapeutic targets.