Human menstrual blood: a renewable and sustainable source of stem cells for regenerative medicine

Menstrual Blood Donation for Endometriosis Research: A Cross-Sectional Survey on Women's Willingness and Potential Barriers

An anonymous online survey in French was used to assess if endometriosis patients would be as ready as unaffected women to donate their menstrual blood for biological research on endometriosis and evaluate potential barriers to such donation. It was distributed in September 2022 by social media and two mailing lists, including a French patient organization. The questionnaire assessed participant age and brief medical history (hormonal contraception, endometriosis diagnosis, type of endometriosis), menstrual experience (menstrual blood abundance, dysmenorrhea), and whether participants would donate menstrual blood. Women who self-declared with an established endometriosis diagnosis versus no endometriosis were compared. Seven hundred seventy-eight women answered the survey. Among women with menstruation (n = 568), 78% are willing to donate menstrual blood for research. Importantly, this proportion was higher in women who declared having an established endometriosis diagnosis (83%, n = 299) compared to self-declared unaffected women (68%, n = 134, p < 0.001). The previous use of a menstrual cup and dysmenorrhea were significantly associated with the willingness to donate menstrual blood, while the use of hormonal contraception was significantly associated with an unwillingness to donate. Only the previous use of the menstrual cup had a predictive value for menstrual blood donation. No significant relationship was observed between menstrual blood donation and age, heavy menstrual bleeding and in endometriosis patients, endometriosis subtypes. In conclusion, women affected or not by endometriosis are largely willing to donate their menstrual blood for research on endometriosis, dysmenorrhea is not a barrier for donation, and women who use a menstrual cup are the more likely to donate.

Menstrual Blood as a Diagnostic Specimen for Human Papillomavirus Genotyping and Genital Tract Infection Using Next-Generation Sequencing as a Novel Diagnostic Tool

BACKGROUND

Menstrual blood (MB) is a convenient specimen type that can be self-collected easily and non-invasively by women. This study assessed the potential application of MB as a diagnostic specimen to detect genital tract infections (GTIs) and human papillomavirus (HPV) infections in women.

METHOD

Genomic DNA was extracted from MB samples. Pacific Bioscience (Pacbio) 16S ribosomal DNA (rDNA) high-fidelity (HiFi) long-read sequencing and HPV PCR were performed.

RESULTS

MB samples were collected from women with a pathological diagnosis of CIN1, CIN2, CIN3 or HPV infection. The sensitivity and positive predictive value (PPV) of high-risk HPV detection using MB were found to be 66.7%. A shift in vaginal flora and a significant depletion in Lactobacillus spp. in the vaginal microbiota communities were observed in the MB samples using 16S rDNA sequencing.

CONCLUSIONS

In this study, we demonstrated that MB is a proper diagnostic specimen of consideration for non-invasive detection of HPV DNA and genotyping using PCR and the diagnosis of GTIs using metagenomic next-generation sequencing (mNGS). MB testing is suitable for all women who menstruate and this study has opened up the possibility of the use of MB as a diagnostic specimen to maintain women's health.

Menstrual blood-derived mesenchymal stem cells combined with collagen I gel as a regenerative therapeutic strategy for degenerated disc after discectomy in rats

BACKGROUND

Annulus fibrosis (AF) defects have been identified as the primary cause of disc herniation relapse and subsequent disc degeneration following discectomy. Stem cell-based tissue engineering offers a promising approach for structural repair. Menstrual blood-derived mesenchymal stem cells (MenSCs), a type of adult stem cell, have gained attention as an appealing source for clinical applications due to their potential for structure regeneration, with ease of acquisition and regardless of ethical issues.

METHODS

The differential potential of MenSCs cocultured with AF cells was examined by the expression of collagen I, SCX, and CD146 using immunofluorescence. Western blot and ELISA were used to examine the expression of TGF-β and IGF-I in coculture system. An AF defect animal model was established in tail disc of Sprague-Dawley rats (males, 8 weeks old). An injectable gel containing MenSCs (about 1*106/ml) was fabricated and transplanted into the AF defects immediately after the animal model establishment, to evaluate its repairment properties. Disc degeneration was assessed via magnetic resonance (MR) imaging and histological staining. Immunohistochemical analysis was performed to assess the expression of aggrecan, MMP13, TGF-β and IGF-I in discs with different treatments. Apoptosis in the discs was evaluated using TUNEL, caspase3, and caspase 8 immunofluorescence staining.

RESULTS

Coculturing MenSCs with AF cells demonstrated ability to express collagen I and biomarkers of AF cells. Moreover, the coculture system presented upregulation of the growth factors TGF-β and IGF-I. After 12 weeks, discs treated with MenSCs gel exhibited significantly lower Pffirrmann scores (2.29 ± 0.18), compared to discs treated with MenSCs (3.43 ± 0.37, p < 0.05) or gel (3.71 ± 0.29, p < 0.01) alone. There is significant higher MR index in disc treated with MenSCs gel than that treated with MenSCs (0.51 ± 0.05 vs. 0.24 ± 0.04, p < 0.01) or gel (0.51 ± 0.05 vs. 0.26 ± 0.06, p < 0.01) alone. Additionally, MenSCs gel demonstrated preservation of the structure of degenerated discs, as indicated by histological scoring (5.43 ± 0.43 vs. 9.71 ± 1.04 in MenSCs group and 10.86 ± 0.63 in gel group, both p < 0.01), increased aggrecan expression, and decreased MMP13 expression in vivo. Furthermore, the percentage of TUNEL and caspase 3-positive cells in the disc treated with MenSCs Gel was significantly lower than those treated with gel alone and MenSCs alone. The expression of TGF-β and IGF-I was higher in discs treated with MenSCs gel or MenSCs alone than in those treated with gel alone.

CONCLUSION

MenSCs embedded in collagen I gel has the potential to preserve the disc structure and prevent disc degeneration after discectomy, which was probably attributed to the paracrine of growth factors of MenSCs.

Neuroprotective Effect of Combined Treatment with Epigallocatechin 3-Gallate and Melatonin on Familial Alzheimer's Disease PSEN1 E280A Cerebral Spheroids Derived from Menstrual Mesenchymal Stromal Cells

Background

Familial Alzheimer's disease (FAD) is caused by mutations in one or more of 3 genes known as AβPP, PSEN1, and PSEN2. There are currently no effective therapies for FAD. Hence, novel therapeutics are needed.

Objective

To analyze the effect of treatment with a combination of epigallocatechin-3-gallate (EGCG) and Melatonin (N-acetyl-5-methoxytryptamine, aMT) in a cerebral spheroid (CS) 3D in vitro model of PSEN 1 E280A FAD.

Methods

We developed a CS in vitro model based on menstrual stromal cells derived from wild-type (WT) and mutant PSEN1 E280A menstrual blood cultured in Fast-N-Spheres V2 medium.

Results

Beta-tubulin III, choline acetyltransferase, and GFAP in both WT and mutant CSs spontaneously expressed neuronal and astroglia markers when grown in Fast-N-Spheres V2 medium for 4 or 11 days. Mutant PSEN1 CSs had significantly increased levels of intracellular AβPP fragment peptides and concomitant appearance of oxidized DJ-1 as early as 4 days, and phosphorylated tau, decreased ΔΨm, and increased caspase-3 activity were observed on Day 11. Moreover, mutant CSs were unresponsive to acetylcholine. Treatment with a combination of EGCG and aMT decreased the levels of all typical pathological markers of FAD more efficiently than did EGCG or aMT alone, but aMT failed to restore Ca2+ influx in mutant CSs and decreased the beneficial effect of EGCG on Ca2+ influx in mutant CSs.

Conclusion

Treatment with a combination of EGCG and aMT can be of high therapeutic value due to the high antioxidant capacity and anti-amyloidogenic effect of both compounds.

Menstrual blood-derived endometrial stem cell, a unique and promising alternative in the stem cell-based therapy for chemotherapy-induced premature ovarian insufficiency

Chemotherapy can cause ovarian dysfunction and infertility since the ovary is extremely sensitive to chemotherapeutic drugs. Apart from the indispensable role of the ovary in the overall hormonal milieu, ovarian dysfunction also affects many other organ systems and functions including sexuality, bones, the cardiovascular system, and neurocognitive function. Although conventional hormone replacement therapy can partly relieve the adverse symptoms of premature ovarian insufficiency (POI), the treatment cannot fundamentally prevent deterioration of POI. Therefore, effective treatments to improve chemotherapy-induced POI are urgently needed, especially for patients desiring fertility preservation. Recently, mesenchymal stem cell (MSC)-based therapies have resulted in promising improvements in chemotherapy-induced ovary dysfunction by enhancing the anti-apoptotic capacity of ovarian cells, preventing ovarian follicular atresia, promoting angiogenesis and improving injured ovarian structure and the pregnancy rate. These improvements are mainly attributed to MSC-derived biological factors, functional RNAs, and even mitochondria, which are directly secreted or indirectly translocated with extracellular vesicles (microvesicles and exosomes) to repair ovarian dysfunction. Additionally, as a novel source of MSCs, menstrual blood-derived endometrial stem cells (MenSCs) have exhibited promising therapeutic effects in various diseases due to their comprehensive advantages, such as periodic and non-invasive sample collection, abundant sources, regular donation and autologous transplantation. Therefore, this review summarizes the efficacy of MSCs transplantation in improving chemotherapy-induced POI and analyzes the underlying mechanism, and further discusses the benefit and existing challenges in promoting the clinical application of MenSCs in chemotherapy-induced POI.

Menstrual blood-derived mesenchymal stromal cells: impact of preconditioning on the cargo of extracellular vesicles as potential therapeutics

BACKGROUND

Mesenchymal stromal cells (MSCs) have been shown to exert their therapeutic effects through the secretion of broad spectrum of paracrine factors, including extracellular vesicles (EVs). Accordingly, EVs are being pursued as a promising alternative to cell-based therapies. Menstrual blood-derived stromal cells (MenSCs) are a type of MSC that, due to their immunomodulatory and regenerative properties, have emerged as an innovative source. Additionally, new strategies of cell priming may potentially alter the concentration and cargo of released EVs, leading to modification of their biological properties. In this study, we aimed to characterize the EVs released by MenSCs and compare their therapeutic potential under three different preconditioning conditions (proinflammatory stimuli, physioxia, and acute hypoxia).

METHODS

MenSCs were isolated from five healthy women. Following culturing to 80% confluence, MenSCs were exposed to different priming conditions: basal (21% O₂), proinflammatory stimuli (IFNγ and TNFα, 21% O₂), physioxia (1-2% O₂), and acute hypoxia (< 1% O₂) for 48-72 h. Conditioned media from MenSCs was collected after 48 h and EVs were isolated by a combination of ultra-filtration and differential centrifugation. An extensive characterization ranging from nano-flow cytometry (nFC) to quantitative high-throughput shotgun proteomics was performed. Bioinformatics analyses were used to derive hypotheses on their biological properties.

RESULTS

No differences in the morphology, size, or number of EVs released were detected between priming conditions. The proteome analysis associated with basal MenSC-EVs prominently revealed their immunomodulatory and regenerative capabilities. Furthermore, quantitative proteomic analysis of differentially produced MenSC-EVs provided sufficient evidence for the utility of the differential preconditioning in purpose-tailoring EVs for their therapeutic application: proinflammatory priming enhanced the anti-inflammatory, regenerative and immunomodulatory capacity in the innate response of EVs, physioxia priming also improves tissue regeneration, angiogenesis and their immunomodulatory capacity targeting on the adaptive response, while acute hypoxia priming, increased hemostasis and apoptotic processes regulation in MenSC-EVs, also by stimulating immunomodulation mainly through the adaptive response.

CONCLUSIONS

Priming of MenSCs under proinflammatory and hypoxic conditions affected the cargo proteome of EVs released, resulting in different therapeutic potential, and thus warrants experimental exploration with the aim to generate better-defined MSC-derived bioproducts.

PSEN1 E280A Cholinergic-like Neurons and Cerebral Spheroids Derived from Mesenchymal Stromal Cells and from Induced Pluripotent Stem Cells Are Neuropathologically Equivalent

Alzheimer's disease (AD) is a chronic neurological condition characterized by the severe loss of cholinergic neurons. Currently, the incomplete understanding of the loss of neurons has prevented curative treatments for familial AD (FAD). Therefore, modeling FAD in vitro is essential for studying cholinergic vulnerability. Moreover, to expedite the discovery of disease-modifying therapies that delay the onset and slow the progression of AD, we depend on trustworthy disease models. Although highly informative, induced pluripotent stem cell (iPSCs)-derived cholinergic neurons (ChNs) are time-consuming, not cost-effective, and labor-intensive. Other sources for AD modeling are urgently needed. Wild-type and presenilin (PSEN)1 p.E280A fibroblast-derived iPSCs, menstrual blood-derived menstrual stromal cells (MenSCs), and umbilical cord-derived Wharton Jelly's mesenchymal stromal cells (WJ-MSCs) were cultured in Cholinergic-N-Run and Fast-N-Spheres V2 medium to obtain WT and PSEN 1 E280A cholinergic-like neurons (ChLNs, 2D) and cerebroid spheroids (CSs, 3D), respectively, and to evaluate whether ChLNs/CSs can reproduce FAD pathology. We found that irrespective of tissue source, ChLNs/CSs successfully recapitulated the AD phenotype. PSEN 1 E280A ChLNs/CSs show accumulation of iAPPβ fragments, produce eAβ42, present TAU phosphorylation, display OS markers (e.g., oxDJ-1, p-JUN), show loss of ΔΨm, exhibit cell death markers (e.g., TP53, PUMA, CASP3), and demonstrate dysfunctional Ca2+ influx response to ACh stimuli. However, PSEN 1 E280A 2D and 3D cells derived from MenSCs and WJ-MSCs can reproduce FAD neuropathology more efficiently and faster (11 days) than ChLNs derived from mutant iPSCs (35 days). Mechanistically, MenSCs and WJ-MSCs are equivalent cell types to iPSCs for reproducing FAD in vitro.

Menstrual Blood-Derived Mesenchymal Stem Cells Encapsulated in Autologous Platelet-Rich Gel Facilitate Rotator Cuff Healing in a Rabbit Model of Chronic Tears

BACKGROUND

Successful management of chronic rotator cuff (RC) tears remains a challenge owing to its limited intrinsic healing capacity and unsatisfactory failure rate. Menstrual blood-derived mesenchymal stem cells (MenSCs) have the potential to differentiate into the chondrogenic or osteogenic lineage. Autologous platelet-rich gel (APG), a gel material derived from platelet-rich plasma (PRP), can be applied as a carrier system for cell delivery and also as a releasing system for endogenous growth factors.

PURPOSE

To investigate the effect of human MenSCs encapsulated in APG (MenSCs@APG) on the healing of chronic RC tears in a rabbit model.

STUDY DESIGN

Controlled laboratory study.

METHODS

After evaluation of the effect of PRP on MenSC proliferation or differentiation, the stem cells were encapsulated in APG for in vivo injection. Supraspinatus tenotomy from the right greater tuberosity was performed on 45 New Zealand White rabbits. After 6 weeks, these rabbits were randomly allocated to 3 supplemental treatments during supraspinatus repair: saline injection (control [CTL] group), APG injection (APG group), and MenSCs@APG injection (MenSCs@APG group). At week 18, these rabbits were sacrificed to harvest the humerus-supraspinatus tendon complexes for micro-computed tomography (CT), histological evaluation, tensile test, and MenSC tracking.

RESULTS

In vitro results showed that APG can stimulate MenSC proliferation and enhance chondrogenic or osteogenic differentiation. In vivo results showed that APG can act as a carrier for delivering MenSCs into the healing site, and also as a stimulator for enhancing the in vivo performance of MenSCs. Micro-CT showed that bone volume/total volume and trabecular thickness of the new bone in the MenSCs@APG group presented significantly larger values than those of the APG or CTL group (P < .05 for all). Histologically, compared with the CTL or APG group, significantly more mature fibrocartilage regenerated at the healing site in the MenSCs@APG group. A large number of human nuclei-stained cells were observed in the MenSCs@APG group, presenting a similar appearance to fibrochondrocytes or osteocytes. Biomechanically, the MenSCs@APG group showed significantly higher failure load and stiffness than the APG or CTL group (P < .05 for all).

CONCLUSION

Human MenSCs@APG facilitated RC healing in a rabbit model of chronic tears.

CLINICAL RELEVANCE

Autogenous MenSCs@APG may be a new stem cell-based therapy for augmenting RC healing in the clinic.

Stem cell-derived exosomes: emerging therapeutic opportunities for wound healing

Wound healing is a dynamic and highly sequential process involving a series of overlapping spatial and temporal phases, including hemostasis, inflammation, proliferation, and tissue remodeling. Mesenchymal stem cells (MSCs) are multipotent stem cells with self-renewal, multidirectional differentiation potential, and paracrine regulation. Exosomes are subcellular vesicular components 30-150 nm in size and are novel carriers of intercellular communication in regulating the biological behaviors of skin cells. Compared to MSCs, MSC-derived exosomes (MSC-exos) possess lower immunogenicity, easy storage, and highly effective biological activity. MSC-exos, mainly derived from adipose-derived stem cells (ADSCs), bone marrow-derived MSCs (BMSCs), human umbilical cord MSCs (hUC-MSCs), and other stem cell types, play a role in shaping the activity of fibroblasts, keratinocytes, immune cells, and endothelial cells in diabetic wounds, inflammatory wound repair, and even wound-related keloid formation. Therefore, this study focuses on the specific roles and mechanisms of different MSC-exos in wound healing, as well as the current limitations and various perspectives. Deciphering the biological properties of MSC-exos is crucial to providing a promising cell-free therapeutic tool for wound healing and cutaneous regeneration.

The differentiation and generation of glucose-sensitive beta like-cells from menstrual blood-derived stem cells using an optimized differentiation medium with platelet-rich plasma (PRP)

Regarding their reversible damage of insulin-producing cells (IPCs) and the inefficiency of treatment methods for type 1 diabetes mellitus (T1DM), scientists decided to produce IPCs from an unlimited source of cells. But the production of these cells is constantly faced with problems such as low differentiation efficiency in cell therapy and regenerative medicine. This study provided an ideal differentiation medium enriched with plasma-rich platelet (PRP) delivery to produce IPCs from menstrual blood-derived stem cells (MenSCs). We compared them with and without PRP differentiation medium. MenSCs were then cultured in two experimental groups: with/without PRP differentiation medium and a control group (undifferentiated MenSCs). After 18 days, differentiated cells were analyzed for expression of pancreatic gene markers by real-time PCR. Immunocytochemical staining was used to detect the presence of insulin and Pdx-1 in the differentiated cells, and insulin and C-peptide secretion response to glucose were tested by ELISA. Finally, the morphology of differentiated cells was examined by an inverted microscope. In vitro studies showed that MenSCs differentiated in the PRP differentiation medium had strong properties of IPCs such as pancreatic islet-like structure. The expression of pancreatic markers at both RNA and protein levels showed that the differentiation efficiency was higher in the PRP differentiation medium. In both experimental groups, the differentiated cells were functional and secreted C-peptide and insulin on glucose stimulation, but the secretion of C-peptide and insulin in the PRP group was higher than those cultured in the without PRP differentiation medium. Our findings showed that using of PRP enriched differentiation medium can promote the differentiation of MenSCs into IPCs compared to the without PRP culture group. Therefore, the use of PRP into differentiation media can be proposed as a new approach to producing IPCs from MenSCs and used in cell-based therapies for T1DM.

Human menstrual blood-derived stem cells reverse sorafenib resistance in hepatocellular carcinoma cells through the hyperactivation of mitophagy

BACKGROUND

Sorafenib is a first-line drug targeting the RTK-MAPK signalling pathway used to treat advanced hepatocellular carcinoma (HCC). However, tumour cells readily develop sorafenib resistance, limiting long-term therapy with this drug. In our previous study, we found that human menstrual blood-derived stem cells (MenSCs) altered the expression of some sorafenib resistance-associated genes in HCC cells. Therefore, we wanted to further explore the feasibility of MenSC-based combination therapy in treating sorafenib-resistant HCC (HCC-SR) cells.

METHODS

The therapeutic efficiency of sorafenib was determined using CCK-8 (Cell Counting Kit-8), Annexin V/PI and clone formation assays in vitro and a xenograft mouse model in vivo. DNA methylation was determined using RT‒PCR and methylated DNA immunoprecipitation (MeDIP). Autophagy was detected by measuring LC3-II degradation and autophagosome maturation. Transmission electron microscopy identified autophagosomes and mitochondria. Physiological functions of mitochondria were assessed by measuring the ATP content, reactive oxygen species (ROS) generation, and mitochondrial membrane potential (MMP).

RESULTS

The tumour suppressor genes BCL2 interacting protein 3 (BNIP3) and BCL2 interacting protein 3 like (BNIP3L) were silenced by promoter methylation and that BNIP3 and BNIP3L levels correlated negatively with sorafenib resistance in HCC-SR cells. Strikingly, MenSCs reversed sorafenib resistance. MenSCs upregulated BNIP3 and BNIP3L expression in HCC-SR cells via tet methylcytosine dioxygenase 2 (TET2)-mediated active demethylation. In HCC-SR cells receiving sorafenib and MenSC combination therapy, pressure from sorafenib and elevated BNIP3 and BNIP3L levels disrupted balanced autophagy. Hyperactivation of mitophagy significantly caused severe mitochondrial dysfunction and eventually led to the autophagic death of HCC-SR cells.

CONCLUSIONS

Our research suggests that combining sorafenib and MenSCs may be a potentially new strategy to reverse sorafenib resistance in HCC-SR cells.

Endometrial Stem Cells and Their Applications in Intrauterine Adhesion

Intrauterine adhesion (IUA), resulting from pregnancy or nonpregnant uterine trauma, is one of the major causes of abnormal menstruation, infertility, or repeated pregnancy loss. Although a few methods, including hysteroscopy and hormone therapy, are routinely used for its diagnosis and treatment, they cannot restore tissue regeneration. Stem cells, which have self-renewal and tissue regeneration abilities, have been proposed as a promising therapy for patients with severe IUAs. In this review, we summarize the origin and features of endometrium-associated stem cells and their applications in the treatment of IUAs based on animal models and human clinical trials. We expect that this information will help to elucidate the underlying mechanism for tissue regeneration and to improve the design of stem cell-based therapies for IUAs.

What Do the Transcriptome and Proteome of Menstrual Blood-Derived Mesenchymal Stem Cells Tell Us about Endometriosis?

Given the importance of menstrual blood in the pathogenesis of endometriosis and the multifunctional roles of menstrual mesenchymal stem cells (MenSCs) in regenerative medicine, this issue has gained prominence in the scientific community. Moreover, recent reviews highlight how robust the integrated assessment of omics data are for endometriosis. To our knowledge, no study has applied the multi-omics approaches to endometriosis MenSCs. This is a case-control study at a university-affiliated hospital. MenSCs transcriptome and proteome data were obtained by RNA-seq and UHPLC-MS/MS detection. Among the differentially expressed proteins and genes, we emphasize ATF3, ID1, ID3, FOSB, SNAI1, NR4A1, EGR1, LAMC3, and ZFP36 genes and MT2A, TYMP, COL1A1, COL6A2, and NID2 proteins that were already reported in the endometriosis. Our functional enrichment analysis reveals integrated modulating signaling pathways such as epithelial–mesenchymal transition (↑) and PI3K signaling via AKT to mTORC1 (↓ in proteome), mTORC1 signaling, TGF beta signaling, TNFA signaling via NFkB, IL6 STAT3 signaling, and response to hypoxia via HIF1A targets (↑ in transcriptome). Our findings highlight primary changes in the endometriosis MenSCs, suggesting that the chronic inflammatory endometrial microenvironment can modulate these cells, providing opportunities for endometriosis etiopathogenesis. Moreover, they identify challenges for future research leveraging knowledge for regenerative and precision medicine in endometriosis.

The Double Engines and Single Checkpoint Theory of Endometriosis

Endometriosis is a chronic disease characterized by the ectopic localization of the endometrial tissue in the peritoneal cavity. Consequently, it causes local pathological changes and systemic symptoms, affecting at least one in every ten women. This disease is difficult to diagnose early, it is prone to dissemination, is difficult to eradicate, tends to recur, and is regarded as “a cancer of no kill”. Indeed, the development of endometriosis closely resembles that of cancer in the way of mutagenesis, pelvic spreading, and immunological adaptation. While retrograde menstruation has been regarded as the primary cause of endometriosis, the role of ovulation and menstrual stimuli in the development of endometriosis has long been overlooked. The development of ovarian and peritoneal endometrioses, similar to the development of high-grade serous carcinoma in the fallopian tube fimbriae with intraperitoneal metastasis, depends highly on the carcinogens released during ovulation. Moreover, endometriosis carries an extremely hypermutated genome, which is non-inferior to the ultra-mutated endometrial cancer. The hypermutation would lead to an overproduction of new proteins or neoantigens. Because of this, the developing endometriosis may have to turn on the PD-1/PDL-1 “self-tolerance” checkpoint to evade immune surveillance, leaving an Achilles tendon for an immune checkpoint blockade. In this review, we present the double engines and single checkpoint theory of the genesis of endometriosis, provide the current pieces of evidence supporting the hypothesis, and discuss the new directions of prevention and treatment.

Endometrium Derived Stem Cells as Potential Candidates in Nervous System Repair

Limited cell division and lack of endogenous repair mechanisms in the central nervous system, hampers tissue repair following neurodegenerative diseases or tissue injuries. Unlike central nervous system; peripheral nervous system has some capacity to repair after injury, but in case of critical sized defects the use of supporting cells in the neural guidance channels seems inevitable to obtain a satisfactory functional recovery. Stem cell therapies have provided new frontiers in the repair of nervous system largely through paracrine secretion mechanisms. The therapeutic potential of stem cells differs according to their tissue of origin, mode of isolation, administration route, and passage number. During the past decades, studies have been focused on stem cells harvested from disposable tissues such as menstrual blood or biopsies from endometrium. These cells are characterized by their high differentiation and proliferation potential, ease of harvest, and lack of ethical concerns. In the current review, we will discuss the prospects and challenges of endometrial stem cells' application in nervous system repair.

Evaluating the effect of conditioned medium from endometrial stem cells on endometriosis-derived endometrial stem cells

Endometriosis is a common, benign gynecological disease which is determined as an overspreading of endometrial tissue in exterior region of the uterine cavity. Evidence suggests that retrograde menstrual blood which contains mesenchymal stem cells with differential gene expression compared to healthy women may play a role in endometriosis creation. We aimed to identify whether the conditioned medium (CM) from menstrual blood-derived mesenchymal stem cells (MenSCs) of healthy women can affect the expression level of inflammatory and stemness genes of MenSCs from endometriosis women. Endometriosis-derived MenSCs (E-MenSCs) were treated with CM derived from healthy women’s MenSCs (non-endometriosis derived MenSCs [NE-MenSCs]). Some CD markers were analyzed by flow cytometer before and after treatment compared with NE-MenSCs, and the expression level of inflammatory and stemness genes was evaluated by real-time PCR. E-MenSCs show different morphology in vitro culture in comparison with NE-MenSCs, which were changed in the presence of CM, into a morphology more similar to normal cells and showed significant decrease expression of CD10 after CM treatment. In our results, the interleukin-1, cyclooxygenase-2, and hypoxia-inducible factor 1α as inflamaturay genes and octamer-binding transcription factor 4, NANOG, and sex determining region Y-box 2 as stemness genes showed significantly different expression level in E-MenSCs after treating with CM. Our study indicates that the expression level of some inflammatory- and stemness-related genes which have differential expression in E-MenSCs compared with NE-MenSCs, could be changed to normal status by using CM derived from NE-MenSCs.

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.

The role of endometrial stem cells in the pathogenesis of endometriosis and their application to its early diagnosis†

Pelvic pain, infertility, and a high postoperative recurrence rate are associated with endometriosis and adversely affect the physical and mental health of patients. Moreover, these factors place a heavy burden on families and society. The identification of endometrial stem cells (EnSCs) in the eutopic endometrium, menstrual blood, and ectopic lesions of women with endometriosis not only provides new research objects in the context of endometriosis but also promotes and improves our understanding of its pathogenesis. Furthermore, based on previous studies, we reasonably suppose that dysfunctions of eutopic EnSCs play a critical role in the onset of endometriosis and directly cause abnormalities in the endometrium; subsequently, retrograde menstruation facilitates the delivery of abnormal endometrial tissues to the ovaries and pelvic cavity, where they ectopically implant, grow, and form ectopic lesions. Additionally, as a chronically progressive disease, there is a delay (3-11 years) from the first onset of symptoms to the diagnosis of endometriosis. Therefore, the development of a method for early diagnosis with high sensitivity and specificity is essential for endometriosis patients and has the potential to enable early treatment, prevent endometriosis progression, and relieve pain in patients. Thus, focusing on EnSCs will contribute to clarifying the potential pathogenesis of endometriosis and provide support for the application of EnSCs as therapeutic and early diagnostic targets in endometriosis treatment.

SUMMARY SENTENCE

Focusing on endometrial stem cells (EnSCs) will contribute to clarifying the potential pathogenesis of endometriosis and provide support for the application of EnSCs as therapeutic and early diagnostic targets in endometriosis treatment.

Small extracellular vesicles from menstrual blood-derived mesenchymal stem cells (MenSCs) as a novel therapeutic impetus in regenerative medicine

Menstrual blood-derived mesenchymal stem cells (MenSCs) have great potential in regenerative medicine. MenSC has received increasing attention owing to its impressive therapeutic effects in both preclinical and clinical trials. However, the study of MenSC-derived small extracellular vesicles (EVs) is still in its initial stages, in contrast to some common MSC sources (e.g., bone marrow, umbilical cord, and adipose tissue). We describe the basic characteristics and biological functions of MenSC-derived small EVs. We also demonstrate the therapeutic potential of small EVs in fulminant hepatic failure, myocardial infarction, pulmonary fibrosis, prostate cancer, cutaneous wound, type-1 diabetes mellitus, aged fertility, and potential diseases. Subsequently, novel hotspots with respect to MenSC EV-based therapy are proposed to overcome current challenges. While complexities regarding the therapeutic potential of MenSC EVs continue to be unraveled, advances are rapidly emerging in both basic science and clinical medicine. MenSC EV-based treatment has great potential for treating a series of diseases as a novel therapeutic strategy in regenerative medicine.

Adult stem cells in endometrial regeneration: Molecular insights and clinical applications

Endometrial damage is an important cause of female reproductive problems, manifested as menstrual abnormalities, infertility, recurrent pregnancy loss, and other complications. These conditions are collectively termed "Asherman syndrome" (AS) and are typically associated with recurrent induced pregnancy terminations, repeated diagnostic curettage and intrauterine infections. Cancer treatment also has unexpected detrimental side effects on endometrial function in survivors independently of ovarian effects. Endometrial stem cells act in the regeneration of the endometrium and in repair through direct differentiation or paracrine effects. Nonendometrial adult stem cells, such as bone marrow-derived mesenchymal stem cells and umbilical cord-derived mesenchymal stem cells, with autologous and allogenic applications, can also repair injured endometrial tissue in animal models of AS and in human studies. However, there remains a lack of research on the repair of the damaged endometrium after the reversal of tumors, especially endometrial cancers. Here, we review the biological mechanisms of endometrial regeneration, and research progress and challenges for adult stem cell therapy for damaged endometrium, and discuss the potential applications of their use for endometrial repair after cancer remission, especially in endometrial cancers. Successful application of such cells will improve reproductive parameters in patients with AS or cancer. Significance: The endometrium is the fertile ground for embryos, but damage to the endometrium will greatly impair female fertility. Adult stem cells combined with tissue engineering scaffold materials or not have made great progress in repairing the injured endometrium due to benign lesions. However, due to the lack of research on the repair of the damaged endometrium caused by malignant tumors or tumor therapies, the safety and effectiveness of such stem cell-based therapies need to be further explored. This review focuses on the molecular insights and clinical application potential of adult stem cells in endometrial regeneration and discusses the possible challenges or difficulties that need to be overcome in stem cell-based therapies for tumor survivors. The development of adult stem cell-related new programs will help repair damaged endometrium safely and effectively and meet fertility needs in tumor survivors.

Different phenotypes and chondrogenic responses of human menstrual blood and bone marrow mesenchymal stem cells to activin A and TGF-β3

BACKGROUND

Due to its low capacity for self-repair, articular cartilage is highly susceptible to damage and deterioration, which leads to the development of degenerative joint diseases such as osteoarthritis (OA). Menstrual blood-derived mesenchymal stem/stromal cells (MenSCs) are much less characterized, as compared to bone marrow mesenchymal stem/stromal cells (BMMSCs). However, MenSCs seem an attractive alternative to classical BMMSCs due to ease of access and broader differentiation capacity. The aim of this study was to evaluate chondrogenic differentiation potential of MenSCs and BMMSCs stimulated with transforming growth factor β (TGF-β3) and activin A.

METHODS

MenSCs (n = 6) and BMMSCs (n = 5) were isolated from different healthy donors. Expression of cell surface markers CD90, CD73, CD105, CD44, CD45, CD14, CD36, CD55, CD54, CD63, CD106, CD34, CD10, and Notch1 was analyzed by flow cytometry. Cell proliferation capacity was determined using CCK-8 proliferation kit and cell migration ability was evaluated by scratch assay. Adipogenic differentiation capacity was evaluated according to Oil-Red staining and osteogenic differentiation according to Alizarin Red staining. Chondrogenic differentiation (activin A and TGF-β3 stimulation) was investigated in vitro and in vivo (subcutaneous scaffolds in nude BALB/c mice) by expression of chondrogenic genes (collagen type II, aggrecan), GAG assay and histologically. Activin A protein production was evaluated by ELISA during chondrogenic differentiation in monolayer culture.

RESULTS

MenSCs exhibited a higher proliferation rate, as compared to BMMSCs, and a different expression profile of several cell surface markers. Activin A stimulated collagen type II gene expression and glycosaminoglycan synthesis in TGF-β3 treated MenSCs but not in BMMSCs, both in vitro and in vivo, although the effects of TGF-β3 alone were more pronounced in BMMSCs in vitro.

CONCLUSION

These data suggest that activin A exerts differential effects on the induction of chondrogenic differentiation in MenSCs vs. BMMSCs, which implies that different mechanisms of chondrogenic regulation are activated in these cells. Following further optimization of differentiation protocols and the choice of growth factors, potentially including activin A, MenSCs may turn out to be a promising population of stem cells for the development of cell-based therapies with the capacity to stimulate cartilage repair and regeneration in OA and related osteoarticular disorders.

Fertility Preservation: The Challenge of Freezing and Transplanting Ovarian Tissue

Cancer treatments are increasingly effective, but can result in iatrogenic premature ovarian insufficiency. Ovarian tissue cryopreservation is the only option available to preserve fertility in prepubertal girls and young women who require immediate chemotherapy. Ovarian tissue transplantation has been shown to restore hormonal cycles and fertility, but a large proportion of the follicle reserve is lost as a consequence of exposure to hypoxia. Another crucial concern is the risk of reimplanting malignant cells together with the grafted tissue. In this review, the authors advance some challenging propositions, from prevention of chemotherapy-related gonadotoxicity to ovarian tissue cryopreservation and transplantation, including the artificial ovary approach.

Treatment potential of bone marrow-derived stem cells in women with diminished ovarian reserves and premature ovarian failure

PURPOSE OF REVIEW

We review the techniques recently tested in both animal models and humans to provide a state-of-the-art on adult stem cell ovarian transplant to achieve ovarian rejuvenation in patients with diminished ovarian reserves.

RECENT FINDINGS

As the firsts reports of spontaneous pregnancies achieved after bone marrow transplantation in oncologic women with primary ovarian insufficiency, increasing evidence supports the regenerative effects of stem cell-based therapies in the ovarian niche. Adult stem cells from several origins promote follicular development, increase ovarian local vascularization, increase follicle and stromal cell proliferation and reduce cell apoptosis and follicular atresia, although they do not modify embryo quality. Therefore, residual quiescent follicles of aged or damaged ovaries might produce competent oocytes in an adequate ovarian environment. Nevertheless, further research is needed to properly evaluate underlying mechanisms, identify best cell sources and design less invasive infusion techniques.

SUMMARY

Stem cells may be a relevant therapeutic alternative for ovary regeneration and follicular development in patients with impaired ovaries, such as poor ovarian responders or women diagnosed with primary ovarian insufficiency.

Human Menstrual Blood Stem Cell-Derived Granulosa Cells Participate in Ovarian Follicle Formation in a Rat Model of Premature Ovarian Failure In Vivo

We recently reported the application of human menstrual blood stem cells' (HuMenSCs) transplantation as a treatment modality in a rat model of premature ovarian failure (POF). We continued to investigate further in this respect. Female rats were injected intraperitoneally with 36 mg/kg busulfan. HuMenSCs were obtained, grown, and analyzed for immunophenotypic features at passage three. The cells were labeled with CM-Dil and infused into the rats. There were four groups: normal, negative control, treatment, and Sham. One month after treatment, the ovaries were collected and weighed. Histological sections were prepared from the ovary and HuMenSCs were tracking. Subsequently, we examined the changes of expression of Bax and B cell lymphoma 2 (Bcl2) genes by real-time polymerase chain reaction assay. One month after HuMenSCs transplantation, these cells were located in the ovarian interstitium and granulosa cells (GCs). The number of TUNEL-positive cells significantly decreased in the treatment group. Also the expression level of Bax genes, unlike Bcl2 gene, significantly decreased compared with negative and sham groups. In our study, HuMenSCs were tracked in ovarian tissues within 2 months after transplantation, and they differentiated into GCs. Therefore, the use of these cells can be a practical and low-cost method for the treatment of POF patients.

Human Menstrual Blood-Derived Mesenchymal Cells Improve Mouse Embryonic Development

There is a constant need for improving embryo culture conditions in assisted reproduction. One possibility is to use mesenchymal stem/stromal cells derived from menstrual blood (mbMSCs), with an endometrial origin. In this study, we sought to analyze the expansion of mouse embryos in a direct coculture model with mbMSCs. Our results showed that after five passages, mbMSCs presented a spindle-shaped morphology, with surface markers that were comparable with the normal mesenchymal cell phenotype. mbMSCs could differentiate into adipogenic and osteogenic lineages and secrete angiopoetin-2 and hepatocyte growth factor. The coculture experiments employed 103 two-cell-stage embryos that were randomly divided into two groups: control (n = 50), embryos cultured in GV-Blast medium, and cocultured mbMSCs (n = 53), embryos cocultured with GV-Blast and mbMSCs. Typically, two to three embryos were placed in a well with 200 μL of culture medium and observed until developmental day 5. After 5 days, the cocultured group had more embryos in the blastocyst stage (69.8%) when compared with the control group (30%) (p < 0.001). It was also found that nearly 57% of blastocysts in the cocultured group reached the hatching stage, while only 13% achieved this stage in the control group (p < 0.001). Analyses of cultured mbMSCs and growth media, in the presence or absence of an embryo, were also performed. Immunofluorescence detected similar levels of collagen I and III and fibronectin in both mbMSCs and cocultured mbMSCs, and similar amounts of growth factors, VEGF, PDGF-AA, and PDGF-BB, were also observed in the conditioned medium, regardless of embryo presence. The present study describes, for the first time, an easy, noninvasive, and autologous method that could potentially increase blastocyst growth rates during assisted reproductive procedures (i.e., in vitro fertilization). It is proposed that this mbMSC coculture strategy enriches the embryonic microenvironment and promotes embryo development. This technique may complement or replace existing assisted reproduction methods and is directly relevant to the field of personalized medicine. Impact statement The study demonstrates a novel and potentially personalized assisted reproduction approach. The search for alternative and autologous methods provides assisted reproduction patients with a better chance of a successful pregnancy. In this study, mesenchymal cells derived from menstrual blood resembled the outside uterine surface and could potentially be employed for improving embryo outgrowth. Our protocol enriches the embryonic microenvironment and facilitates high-quality single-embryo transfer.

Safety of menstrual blood-derived stromal cell transplantation in treatment of intrauterine adhesion

BACKGROUND

Intrauterine adhesion (IUA) can cause serious damage to women's reproductive health, yet current treatment methods are difficult to achieve satisfactory results. In our previous studies, we demonstrated that menstrual-derived stromal stem cells (MenSCs), with high proliferative capacity and self-renewal ability, have a powerful therapeutic effect in patients with severe IUA. However, safety assessment of MenSCs transplantation is essential for its further application.

AIM

To evaluate the short-, medium-, and long-term biosafety of MenSCs via intrauterine transplantation in a rat model of IUA, with a focus on toxicity and tumorigenicity.

METHODS

MenSCs were injected into the sub-serosal layer of the uterus in an IUA rat model, for 3 d, 3 mo, and 6 mo separately, to monitor the corresponding acute, sub-chronic, and chronic effects. Healthy rats of the same age served as negative controls. Toxicity effects were evaluated by body weight, organ weight, histopathology, hematology, and biochemistry tests. Tumorigenicity of MenSCs was investigated in Balb/c-nu mice in vivo and by colony formation assays in vitro.

RESULTS

Compared with the same week-old control group, all of the IUA rats receiving MenSC transplantation demonstrated no obvious changes in body weight, main organ weight, or blood cell composition during the acute, sub-chronic, and chronic observation periods. At the same time, serum biochemical tests showed no adverse effects on metabolism or liver and kidney function. After 4 wk of subcutaneous injection of MenSCs in Balb/c-nu nude mice, no tumor formation or cell metastasis was observed. Moreover, there was no tumor colony formation of MenSCs during soft agar culture in vitro.

CONCLUSION

There is no acute, sub-chronic, or chronic poisoning, infection, tumorigenesis, or endometriosis in rats with IUA after MenSC transplantation. The above results suggest that intrauterine transplantation of MenSCs is safe for endometrial treatment.

Menstrual blood-derived stem cells: toward therapeutic mechanisms, novel strategies, and future perspectives in the treatment of diseases

Menstrual blood-derived stem cells (MenSCs) have great potential in the treatment of various diseases. As a novel type of mesenchymal stem cells (MSCs), MenSCs have attracted more interest due to their therapeutic effects in both animal models and clinical trials. Here, we described the differentiation, immunomodulation, paracrine, homing, and engraftment mechanisms of MenSCs. These include differentiation into targeting cells, immunomodulation with various immune cells, the paracrine effect on secreting cytokines, and homing and engraftment into injured sites. To better conduct MenSC-based therapy, some novel hotspots were proposed such as CRISPR (clustered regularly interspaced short palindromic repeats)/cas9-mediated gene modification, exosomes for cell-free therapy, single-cell RNA sequence for precision medicine, engineered MenSC-based therapy for the delivery platform, and stem cell niches for improving microenvironment. Subsequently, current challenges were elaborated on, with regard to age of donor, dose of MenSCs, transplantation route, and monitoring time. The management of clinical research with respect to MenSC-based therapy in diseases will become more normative and strict. Thus, a more comprehensive horizon should be considered that includes a combination of traditional solutions and novel strategies. In summary, MenSC-based treatment has a great potential in treating diseases through diverse strategies, and more therapeutic mechanisms and novel strategies need to be elucidated for future regenerative medicine and clinical applications.