Efficacy of Mesenchymal Stem Cell-Derived Extracellular Vesicles in the Animal Model of Female Reproductive Diseases: A Meta-Analysis

Development of regenerative therapies targeting fibrotic endometrium in intrauterine adhesion or thin endometrium to restore uterine function

Intrauterine adhesions (IUA) and thin endometrium (TE) represent significant challenges in human reproduction. The condition arises frequently from damage to the endometrial basal layer, leading to fibrous tissue replacing the functional endometrium and impairing the uterus's ability to accept embryo implantation. Conventional treatments, mainly including hysteroscopic adhesiolysis and estrogen therapies, have shown limited success, particularly in severe cases. Regenerative medicine, with its focus on stem cell-based therapies and biomaterials, offers a promising avenue for restoring endometrial function and structure. This review synthesizes the current landscape of endometrial regeneration, focusing on the therapeutic potential of stem cells, the supportive role of biomaterials, and the importance of understanding molecular mechanisms to develop effective strategies for reconstruction of endometrial functional and fertility restoration.

"Thin endometrium" at single-cell resolution

Thin endometrium is defined as an endometrial thickness of less than 7 mm in the midluteal phase of the menstrual cycle, a condition often seen in women of childbearing age with a history of uterine trauma, such as dilation and curettage or intrauterine adhesion separation. This inadequate thickness poses a substantial threat to endometrial receptivity and subsequent pregnancy, particularly during infertility treatments. Despite efforts to stimulate endometrial growth through agents such as high doses of estrogen, improvements in both endometrial thickness and pregnancy rates have been marginal. Consequently, it is referred to as "unresponsive endometrium or refractory thin endometrium." To explore novel therapeutic avenues, a deeper understanding of the underlying mechanisms is urgently needed. In this review, we examine recent single-cell sequencing studies that have identified key alterations in cell populations, signaling pathways, and cell-cell communication in the endometrium during the late proliferative phase, comparing normal endometrium and thin endometrium following uterine injuries. Evidence suggests that endometrial injury acted as a primary contributor, initiating an accelerated aging process across diverse cell types and establishing an environment characterized by immune incompetence and dysfunction. Senescence, a consequence of this injury, may impede endometrial proliferation, disrupt vascular development, and lead to fibrosis, creating a milieu of abnormal receptivity-a critical downstream event associated with implantation failure and infertility. Addressing these identified challenges necessitates advancing research to comprehend and target the key factors contributing to thin endometrium, a crucial step for clinical translation.

BDNF secreted by mesenchymal stem cells improves aged oocyte quality and development potential by activating the ERK1/2 pathway

BACKGROUND

Reduced oocyte quality is a key factor in age-related fertility decline, and there are no effective treatments available. The secretome of mesenchymal stem cells (MSC-sec) contains various bioactive factors and has the potential to improve oocyte quality. This study aimed to investigate the effective component and molecular mechanism of MSC-sec involved in improving oocyte quality from aged mice and humans.

METHODS

Immunofluorescence and chromosome spread were performed to investigate the effects of secretome from human umbilical cord-MSC on spindle assembly and aneuploidy in aged mouse oocytes. Brain-derived neurotrophic factor (BDNF) and its neutralization antibody was supplemented in both in vitro and in vivo experiments to verify the effective component in MSC-sec. RNA-seq analysis was used to reveal the alterations in maternal mRNA degradation in aged mouse oocytes after MSC-sec treatment. In vitro culture of oocytes from aged women was also used to verify the effectiveness of BDNF in improving oocyte quality.

RESULTS

MSC-sec treatment significantly increased first polar body emission, improved spindle assembly, promoted maternal RNA degradation, and reduced aneuploidy rate in aged mouse oocytes. While the addition of BDNF neutralization antibody blocked the effects of MSC-sec, BDNF alone also increased the oocyte quality from aged mice. Mechanistically, both MSC-sec and BDNF rescued the quality of aged mouse oocytes by activating the ERK1/2 signaling pathway to increase the expression of DAZL and BTG4. In situ injection of MSC-sec or BDNF into aged mouse ovaries significantly improved oocyte quality and early embryonic development. Finally, we demonstrated that BDNF treatment increased both the fertilization rate and blastocyst formation rate of aged human oocytes.

CONCLUSION

These findings demonstrate that BDNF secreted by mesenchymal stem cells can improve the quality and development potential of oocytes from both aged mice and humans by activating the ERK1/2 signaling pathway, suggesting that it has the potential to mitigate age-related declines in oocyte quality.

Reproductomics: Exploring the Applications and Advancements of Computational Tools

Over recent decades, advancements in omics technologies, such as proteomics, genomics, epigenomics, metabolomics, transcriptomics, and microbiomics, have significantly enhanced our understanding of the molecular mechanisms underlying various physiological and pathological processes. Nonetheless, the analysis and interpretation of vast omics data concerning reproductive diseases are complicated by the cyclic regulation of hormones and multiple other factors, which, in conjunction with a genetic makeup of an individual, lead to diverse biological responses. Reproductomics investigates the interplay between a hormonal regulation of an individual, environmental factors, genetic predisposition (DNA composition and epigenome), health effects, and resulting biological outcomes. It is a rapidly emerging field that utilizes computational tools to analyze and interpret reproductive data, with the aim of improving reproductive health outcomes. It is time to explore the applications of reproductomics in understanding the molecular mechanisms underlying infertility, identification of potential biomarkers for diagnosis and treatment, and in improving assisted reproductive technologies (ARTs). Reproductomics tools include machine learning algorithms for predicting fertility outcomes, gene editing technologies for correcting genetic abnormalities, and single cell sequencing techniques for analyzing gene expression patterns at the individual cell level. However, there are several challenges, limitations and ethical issues involved with the use of reproductomics, such as the applications of gene editing technologies and their potential impact on future generations are discussed. The review comprehensively covers the applications and advancements of reproductomics, highlighting its potential to improve reproductive health outcomes and deepen our understanding of reproductive molecular mechanisms.

Mesenchymal stem cell-derived extracellular vesicles therapy for primary ovarian insufficiency: a systematic review and meta-analysis of pre-clinical studies

BACKGROUND

Primary ovarian insufficiency (POI) manifests with hormonal imbalances, menstrual irregularities, follicle loss, and infertility. Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) are emerging as a promising treatment for POI. This systematic review aims to assess the effects of MSC-EVs on follicle number, hormonal profile, and fertility in POI animal models.

METHODS

A systematic search of PubMed, Scopus, and Web of Science databases up to December 14th, 2023 was conducted. Two reviewers independently conducted screening, risk of bias assessment, and data extraction. Meta-analysis was performed to analyze treatment versus control outcomes using a random effects model. Publication bias was assessed using Egger's regression test and sensitivity analysis was assessed using the leave-one-out method. Subgroup analyses and meta-regressions were conducted based on EV source, induction model, type of animal, study quality, administration route, administration frequency and route, and dose.

RESULTS

a total of 29 studies were included. MSC-EVs treatment significantly increased total follicle count (SMD, (95CI), p-value; 3.56, (0.91, 6.21), < 0.001), including primordial (SMD, (95CI), p-value; 2.86, (1.60, 4.12), < 0.001), primary (SMD, (95CI), p-value; 3.17, (2.28, 4.06), < 0.001), mature (SMD, (95CI), p-value; 2.26, (1.02, 3.50), < 0.001), and antral follicles (SMD, (95CI), p-value; 2.44, (1.21, 3.67), < 0.001). Administration frequency and route did not affect this outcome, but EV source affected primordial, primary, secondary and antral follicle count. Additionally, MSC-EVs treatment elevated anti-müllerian hormone (SMD, (95CI); 3.36, (2.14, 4.58)) and estradiol (SMD, (95CI); 3.19, (2.20, 4.17)) levels while reducing follicle stimulating hormone levels (SMD, (95CI); -2.68, (-4.42, -0.94)). Unlike EV source, which had a significant impact on all three hormones, administration frequency, route, and EV dose did not affect this outcome. Moreover, treatment increased offspring number (SMD, (95CI); 3.70, (2.17, 5.23)) and pregnancy odds (OR, (95CI); 10.25, (4.29, 24.46)) compared to controls. Publication bias and a high level of heterogeneity was evident in all analyses, except for the analysis of the pregnancy odds. However, sensitivity analysis indicated that all of the analyses were stable.

CONCLUSION

MSC-EVs therapy shows promise for POI treatment, potentially facilitating clinical translation. However, Further research is warranted to optimize methodology and assess side effects.

Stem cell-derived extracellular vesicles in premature ovarian failure: an up-to-date meta-analysis of animal studies

BACKGROUND

There has been a significant surge in animal studies of stem cell-derived extracellular vesicles (EVs) therapy for the treatment of premature ovarian failure (POF) but its efficacy remains unknown and a comprehensive and up-to-date meta-analysis is lacking. Before clinical translation, it is crucial to thoroughly understand the overall impact of stem cell-derived EVs on POF.

METHODS

PubMed, EMBASE, Cochrane Library, Web of Science were searched up to February 18, 2024. The risk of bias was evaluated according to Cochrane Handbook criteria, while quality of evidence was assessed using the SYRCLE system. The PRISMA guidance was followed. Trial sequential analysis was conducted to assess outcomes, and sensitivity analysis and publication bias analysis were performed using Stata 14.

RESULTS

Data from 25 studies involving 339 animals were extracted and analyzed. The analysis revealed significant findings: stem cell-derived EVs increase ovary weight (SMD = 3.88; 95% CI: 2.50 ~ 5.25; P < 0.00001; I2 = 70%), pregnancy rate (RR = 3.88; 95% CI: 1.94 ~ 7.79; P = 0.0001; I2 = 0%), count of births (SMD = 2.17; 95% CI: 1.31 ~ 3.04; P < 0.00001; I2 = 69%) and counts of different types of follicles. In addition, it elevates the level of AMH (SMD = 4.15; 95% CI: 2.75 ~ 5.54; P < 0.00001; I2 = 88%) and E2 (SMD = 2.88; 95% CI: 2.02 ~ 3.73; P < 0.00001; I2 = 80%) expression, while reducing FSH expression (SMD = -5.05; 95% CI: -6.60 ~ -3.50; P < 0.00001; I2 = 90%). Subgroup analysis indicates that the source of EVs, animal species, modeling method, administration route, and test timepoint affected efficacy. Trial sequential analysis showed that there was sufficient evidence to confirm the effects of stem cell-derived EVs on birth counts, ovarian weights, and follicle counts. However, the impact of stem cell-derived EVs on pregnancy rates needs to be further demonstrated through more animal experimental evidence.

CONCLUSIONS

Stem cell-derived EVs demonstrate safety and efficacy in treating POF animal models, with potential improvements in fertility outcomes.

TRIAL REGISTRATION

PROSPERO registration number: CRD42024509699.

Fertility protection: a novel approach using pretreatment with mesenchymal stem cell exosomes to prevent chemotherapy-induced ovarian damage in a mouse model

BACKGROUND

Primary ovarian insufficiency refers to the loss of ovarian function before the age of 40 years and leads to amenorrhea and infertility. Primary ovarian insufficiency has diverse causes, but a common cause is exposure to gonadotoxic chemotherapy used in cancer treatment. Because of the risk for developing primary ovarian insufficiency, patients who want to preserve their fertility may consider various procedures for fertility preservation. However, current fertility preservation options are highly invasive, carry substantial risks, and have uncertain success rates. Recent studies from our group and others reported that mesenchymal stem cells and mesenchymal stem cell-derived exosomes can restore ovarian function in preclinical models of primary ovarian insufficiency by restoring damaged cells and inhibiting apoptosis. Although the restorative effect of mesenchymal stem cell-derived exosomes has been well reported in previous studies, the potential of mesenchymal stem cell-derived exosomes in preventing ovarian damage has not been fully elucidated.

OBJECTIVE

This study hypothesized that the antiapoptotic potential of mesenchymal stem cell-derived exosomes may protect ovarian tissue from chemotherapy-induced damage.

STUDY DESIGN

In this study, we delivered mesenchymal stem cell-derived exosomes directly into the ovaries of mice before administration of chemotherapy. A total of 60 mice were divided into 3 groups (20 per group), which were labeled the control, chemotherapy, and fertility protection groups. Only the fertility protection group mice received exosomes, whereas the control and chemotherapy group mice received saline. After exosome injection, the chemotherapy and fertility protection groups of mice were subjected to chemotherapy to induce ovarian damage. After chemotherapy, we evaluated the protective effects of exosome treatment on ovarian function, such as estrous cyclicity, serum hormone levels, and the fertility rate, by comparing these outcomes between the chemotherapy and fertility protection groups. These outcomes were also compared with those of the control group for comparison with outcomes under healthy conditions.

RESULTS

After intraovarian injection of exosomes before chemotherapy, the mice were able to maintain their estrous cycle (4- to 5-day cyclicity), serum anti-müllerian hormone level (66.06±26.40 ng/mL, not significantly different from that of the healthy controls), folliculogenesis (32.2±11.3 in the chemotherapy group vs 46.4±14.1 in the fertility protection group; P<.05), expression of the steroidogenic acute regulatory protein gene (a the steroidogenesis marker) (0.44±0.11-fold expression in the chemotherapy group and 0.88±0.31-fold expression in the fertility protection group; P<.05), and fertility (2 of 8 in the chemotherapy group and 5 of 8 in the fertility protection group), thereby showing prevention of chemotherapy-induced damage. We found that exosome treatment before chemotherapy can preserve ovarian function and protect fertility through the overexpression of ATP synthase-binding cassette transporters, such as ABCB1b (10.17±17.75-fold expression in the chemotherapy group and 44.14±33.25-fold expression in the fertility protection group; P<.05) and ABCC10 (3.25±0.59-fold expression in the chemotherapy group and 5.36±1.86-fold expression in the fertility protection group; P<.05).

CONCLUSION

In this study, we present a novel fertility protection method using mesenchymal stem cell-derived exosomes. We concluded that mesenchymal stem cell-derived exosomes are a promising and simple treatment option for fertility protection in reproductive-aged patients who are receiving gonadotoxic chemotherapy.

Bioengineering approaches for the endometrial research and application

The endometrium undergoes a series of precise monthly changes under the regulation of dynamic levels of ovarian hormones that are characterized by repeated shedding and subsequent regeneration without scarring. This provides the potential for wound healing during endometrial injuries. Bioengineering materials highlight the faithful replication of constitutive cells and the extracellular matrix that simulates the physical and biomechanical properties of the endometrium to a larger extent. Significant progress has been made in this field, and functional endometrial tissue bioengineering allows an in-depth investigation of regulatory factors for endometrial and myometrial defects in vitro and provides highly therapeutic methods to alleviate obstetric and gynecological complications. However, much remains to be learned about the latest progress in the application of bioengineering technologies to the human endometrium. Here, we summarize the existing developments in biomaterials and bioengineering models for endometrial regeneration and improving the female reproductive potential.

Therapeutic Potential of Mesenchymal Stem Cell-Derived Extracellular Vesicles to Treat PCOS

Polycystic ovary syndrome (PCOS) is known as the most common endocrine disorder in women. Previously, we suggested that human mesenchymal stem cells (MSCs) can reverse the PCOS condition by secreting factors. Here, we evaluated the therapeutic capability of MSC-derived extracellular vesicles (EVs), also known as exosomes, in both in vitro and in vivo PCOS models. Exosomes were used to treat androgen-producing H293R cells and injected in a mouse model through intraovarian and intravenous injection into a letrozole (LTZ)-induced PCOS mouse model. We assessed the effects of the exosomes on androgen-producing cells or the PCOS mouse model by analyzing steroidogenic gene expression (quantitative real-time polymerase chain reaction (qRT-PCR)), body weight change, serum hormone levels, and fertility by pup delivery. Our data show the therapeutic effect of MSC-derived EVs for reversing PCOS conditions, including fertility issues. Interestingly, intravenous injection was more effective for serum glucose regulation, and an intraovarian injection was more effective for ovary restoration. Our study suggests that MSC-derived exosomes can be promising biopharmaceutics for treating PCOS conditions as a novel therapeutic option. Despite the fact that we need more validation in human patients, we may evaluate this novel treatment option for PCOS with the following clinical trials.