Comparison of endometrial regenerative cells and bone marrow stromal cells

Defining optimal electrospun membranes to enhance biological activities of human endometrial MSCs

Introduction

Human endometrial mesenchymal stem cells (H-EMSCs) can inhibit endometrial fibrosis and repair damaged endometrium. However, direct cell injection into dam-aged endometrium shows limited cell survival. Cell seeding onto biomaterial-based electrospun membranes could improve H-EMSCs' survival and prolong their stay at the damaged endometrium. Polycaprolactone (PCL), silk fibroin (SF) and hyaluronic acid (HA) are synthetic or natural biomaterials used by the biomedicine field, however, their effects on the biological activities of H-EMSCs remain unclear.

Methods

In this study, CD90+CD73+CD45- H-EMSCs were extracted from human endometrium and H-EMSCs showed enhanced adhesion, proliferation on PCL-HA vs. PCL, PCL-SF, establishing the potential of the composite to address cell survival issues.

Results

H-EMSCs cultured on PCL-HA showed decreased IL-6 gene expression and increased IL-10, VEGFA, TGF-β gene expression vs. PCL-SF, establishing the potential to create a favorable micro-environment for generating vascularized endometrial tissues. PCL, PCL-SF, PCL-HA all supported CD90 and Meflin expression of the seeded H-EMSCs, establishing PCL as a platform to form enhanced biomaterial composites for endometrial repair in the future.

Discussion

This study provided significant evidence sup-porting the potential of appropriately tailored composites of PCL and HA to moder-ate inflammation and wound-healing, which can be applied for endometrial tissue repair and regeneration.

Human Decidual Mesenchymal Stem Cells Obtained From Early Pregnancy Improve Cardiac Revascularization Postinfarction by Activating Ornithine Metabolism

Background

Compared with bone marrow mesenchymal stem cells (BMSCs), decidual mesenchymal stem cells (DMSCs) are easy to obtain and exhibit excellent angiogenic effects, but their role in cell transplantation after myocardial infarction (MI) remains unclear.

Methods

BMSCs and DMSCs were harvested from healthy donors. The effects of both cell types on angiogenesis were observed in vitro. Metabonomics analysis was performed to compare different metabolites and screen critical metabolic pathways. A murine model of acute myocardial infarction (AMI) was established, which was randomized into five groups (control, BMSC, DMSC, DMSC + ODCshRNA and BMSC + ODC consisting of 50 animals, equally divided into each group). The therapeutic effect of DMSCs on MI in rats was assessed based on neovascularization and cardiac remodeling.

Results

DMSCs exhibited a better angiogenic effect on human umbilical vein endothelial cells (HUVECs) than BMSCs in vitro. In addition, ornithine metabolism, which is associated with vascularization, was significantly increased in DMSCs. The transplantation of DMSCs in the rat MI model significantly enhanced angiogenesis of the infarct border area and improved cardiac remodeling and dysfunction postinfarction compared with BMSCs. Furthermore, inhibition of ornithine metabolism by silencing ornithine decarboxylase (ODC) in DMSCs partly abolished the benefits of DMSC transplantation.

Conclusion

Compared with BMSCs, DMSCs exhibited better efficacy in improving revascularization and heart remodeling post-MI via the activation of ODC-associated ornithine metabolism.

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.

Characterizing the Effects of Synergistic Thermal and Photo-Cross-Linking during Biofabrication on the Structural and Functional Properties of Gelatin Methacryloyl (GelMA) Hydrogels

Gelatin methacryloyl (GelMA) hydrogels have emerged as promising and versatile biomaterial matrices with applications spanning drug delivery, disease modeling, and tissue engineering and regenerative medicine. GelMA exhibits reversible thermal cross-linking at temperatures below 37 °C due to the entanglement of constitutive polymeric chains, and subsequent ultraviolet (UV) photo-cross-linking can covalently bind neighboring chains to create irreversibly cross-linked hydrogels. However, how these cross-linking modalities interact and can be modulated during biofabrication to control the structural and functional characteristics of this versatile biomaterial is not well explored yet. Accordingly, this work characterizes the effects of synergistic thermal and photo-cross-linking as a function of GelMA solution temperature and UV photo-cross-linking duration during biofabrication on the hydrogels' stiffness, microstructure, proteolytic degradation, and responses of NIH 3T3 and human adipose-derived stem cells (hASC). Smaller pore size, lower degradation rate, and increased stiffness are reported in hydrogels processed at lower temperature or prolonged UV exposure. In hydrogels with low stiffness, the cells were found to shear the matrix and cluster into microspheroids, while poor cell attachment was noted in high stiffness hydrogels. In hydrogels with moderate stiffness, ones processed at lower temperature demonstrated better shape fidelity and cell proliferation over time. Analysis of gene expression of hASC encapsulated within the hydrogels showed that, while the GelMA matrix assisted in maintenance of stem cell phenotype (CD44), a higher matrix stiffness resulted in higher pro-inflammatory marker (ICAM1) and markers for cell-matrix interaction (ITGA1 and ITGA10). Analysis of constructs with ultrasonically patterned hASC showed that hydrogels processed at higher temperature possessed lower structural fidelity but resulted in more cell elongation and greater anisotropy over time. These findings demonstrate the significant impact of GelMA material formulation and processing conditions on the structural and functional properties of the hydrogels. The understanding of these material-process-structure-function interactions is critical toward optimizing the functional properties of GelMA hydrogels for different targeted applications.

Stimulator of Interferon Genes Signaling Pathway and its Role in Anti-tumor Immune Therapy

Stimulator of interferon genes is an important innate immune signaling molecule in the body and is involved in the innate immune signal transduction pathway induced by pathogen-associated molecular patterns or damage-associated molecular patterns. Stimulator of interferon genes promotes the production of type I interferon and thus plays an important role in the innate immune response to infection. In addition, according to a recent study, the stimulator of interferon genes pathway also contributes to anti-inflammatory and anti-tumor reactions. In this paper, current researches on the Stimulator of interferon genes signaling pathway and its relationship with tumor immunity are reviewed. Meanwhile, a series of critical problems to be addressed in subsequent studies are discussed as well.

Culture density of menstrual blood-derived stromal/stem cells determines the quality of T cell responses: An experimental study

BACKGROUND

Menstrual blood-derived stromal/stem cells (MenSCs) are a new population of refreshing and highly proliferative stem cells. Immunomodulatory effects of MenSCs profoundly depend on their relative density.

OBJECTIVE

To find whether MenSCs cultured at varying numbers would differentially affect the allogenic peripheral blood mononuclear cells (PBMCs) key features.

MATERIALS AND METHODS

PBMCs were co-cultured with various MenSCs numbers. PBMCs proliferation was investigated via3 H-thymidine incorporation. Flow cytometry was used to assess human leukocyte antigen (HLA)-DR, HLA-ABC, HLA-G, and co-stimulatory markers on MenSCs and the percentage of regulatory T cells (Tregs) among PBMCs. The concentration of cytokines was determined in supernatant of co-cultures.

RESULTS

The support of PBMCs proliferation at low MenSCs densities correlated with higher levels of pro-inflammatory interferon gamma (IFN-γ) in MenSCs/PBMCs co-culture and increased expression of HLA-DR by MenSCs. On the other hand, the suppressive property of MenSCs at higher densities was independent of Treg frequency, but correlated with a high concentration of Interleukin (IL)-6 and IL-10 in the co-cultures.

CONCLUSION

Totally, at different seeding densities, MenSCs could differentially interact with PBMCs leading to significant changes in the level of anti- and/or pro-inflammatory factors. These preliminary in vitro results are suggested to be taken into consideration in experimental models of MenSC-based immunomodulation. Nonetheless, for efficient utilization of MenSCs anti-inflammatory features in pre-clinical disease models, we still need to broaden our knowledge on MenSC-immune system cross-talk; this could play a part in designing more optimized MenSCs injection modalities in the case of future pre-clinical and subsequently clinical settings.

Activation of the Hippo/TAZ pathway is required for menstrual stem cells to suppress myofibroblast and inhibit transforming growth factor β signaling in human endometrial stromal cells

STUDY QUESTION

Can menstrual stem cells (MenSCs) inhibit myofibroblast differentiation and reverse transforming growth factor β (TGFβ)-mediated activation of myofibroblast phenotypes in human endometrial stromal cells (ESCs)?

SUMMARY ANSWER

MenSCs suppressed endometrial myofibroblast differentiation and reversed TGFβ-mediated activation of myofibroblast phenotypes, which might be associated with activation of the Hippo/TAZ pathway.

WHAT IS KNOWN ALREADY

The potential effect of MenSCs as a cell therapy include attenuation of intrauterine adhesions, but the underlying mechanisms by which MenSCs exerts these effects are not entirely understood.

STUDY DESIGN, SIZE, DURATION

We evaluated the antagonistic effects of MenSCs on myofibroblast differentiation as well as the broader effect of the Hippo/TAZ signaling pathway on TGFβ-mediated induction of myofibroblast gene expression. The study design was based on a cohort of clinical proliferative phase endometrial samples obtained from three healthy premenopausal females with regular menstrual cycles.

PARTICIPANTS/MATERIALS, SETTING, METHODS

ESCs were cocultured with MenSCs or in MenSC-conditioned medium. Fibrotic markers (αSMA, collagen I, CTGF and fibronectin) as well as proliferation and wound-healing abilities were evaluated. Components of the Hippo/TAZ pathway (TAZ, p-TAZ, MOB1, p-MOB1, LATS1 and p-LATS1) were also investigated. Cell Counting Kit 8, wound healing assay, real-time PCR, western blotting, immunofluorescence and shRNA knockdown approaches were used to validate the findings.

MAIN RESULTS AND THE ROLE OF CHANCE

MenSCs inhibited myofibroblast activation, resulting in more rapid proliferation of ESCs. MenSCs downregulated the expression of myofibroblast markers αSMA and collagen I and promoted endometrial wound healing. Coculture with MenSCs also attenuated the TGFβ-mediated increase in expression of fibrotic marker genes αSMA, collagen I, CTGF and fibronectin, and restored the wound-healing ability inhibited by TGFβ. MenSCs induced Hippo/TAZ pathway activation, resulting in nuclear export and cytoplasmic retention of TAZ. TAZ inhibition was demonstrated to have similar effects even in the absence of MenSCs, and inhibition of TAZ was sufficient to attenuate TGFβ-mediated myofibroblast activation.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

This study included only in vitro experiments. Thus, additional data from in vivo experiments are needed in a future study.

WIDER IMPLICATIONS OF THE FINDINGS

The Hippo/TAZ pathway may be an important therapeutic target for endometrial fibrosis.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the National Natural Science Foundation of China (No. 81601236) and Zhejiang Provincial Natural Science Foundation of China (LY19H040009). None of the authors has any competing interests to declare.

Endometrial and Menstrual Blood Mesenchymal Stem/Stromal Cells: Biological Properties and Clinical Application

A highly proliferative mesenchymal stem/stromal cell (MSC) population was recently discovered in the dynamic, cyclically regenerating human endometrium as clonogenic stromal cells that fulfilled the International Society for Cellular Therapy (ISCT) criteria. Specific surface markers enriching for clonogenic endometrial MSC (eMSC), CD140b and CD146 co-expression, and the single marker SUSD2, showed their perivascular identity in the endometrium, including the layer which sheds during menstruation. Indeed, cells with MSC properties have been identified in menstrual fluid and commonly termed menstrual blood stem/stromal cells (MenSC). MenSC are generally retrieved from menstrual fluid as plastic adherent cells, similar to bone marrow MSC (bmMSC). While eMSC and MenSC share several biological features with bmMSC, they also show some differences in immunophenotype, proliferation and differentiation capacities. Here we review the phenotype and functions of eMSC and MenSC, with a focus on recent studies. Similar to other MSC, eMSC and MenSC exert immunomodulatory and anti-inflammatory impacts on key cells of the innate and adaptive immune system. These include macrophages, T cells and NK cells, both in vitro and in small and large animal models. These properties suggest eMSC and MenSC as additional sources of MSC for cell therapies in regenerative medicine as well as immune-mediated disorders and inflammatory diseases. Their easy acquisition via an office-based biopsy or collected from menstrual effluent makes eMSC and MenSC attractive sources of MSC for clinical applications. In preparation for clinical translation, a serum-free culture protocol was established for eMSC which includes a small molecule TGFβ receptor inhibitor that prevents spontaneous differentiation, apoptosis, senescence, maintains the clonogenic SUSD2+ population and enhances their potency, suggesting potential for cell-therapies and regenerative medicine. However, standardization of MenSC isolation protocols and culture conditions are major issues requiring further research to maximize their potential for clinical application. Future research will also address crucial safety aspects of eMSC and MenSC to ensure these protocols produce cell products free from tumorigenicity and toxicity. Although a wealth of data on the biological properties of eMSC and MenSC has recently been published, it will be important to address their mechanism of action in preclinical models of human disease.

Menstrual Blood-Derived Mesenchymal Stem Cells: Women's Attitudes, Willingness, and Barriers to Donation of Menstrual Blood

Background: Menstrual blood contains mesenchymal stem cells (MenSC), considered a potential "off-the-shelf" treatment for a range of diseases and medical conditions. Samples of menstrual blood can be collected painlessly, inexpensively, and as frequently as every month for cell therapy. While there has been considerable previous research into the clinical advantages of MenSC, there is currently little understanding of potential donors' attitudes regarding menstrual blood donation and MenSC. Methods: One hundred women 18 years of age or over were surveyed to understand attitudes and potential barriers to menstrual blood donation. The questionnaire assessed participant age and brief medical history (giving birth, donating blood, donating stem cells), menstrual experience (period rating, preferred menstrual hygiene products), and whether participants would donate MenSC or accept MenSC therapy. Results: MenSC was met with a generally positive response, with 78% of menstruating women willing to donate menstrual blood. No significant relationship was recognized between willingness to donate menstrual blood with age, history of childbirth or blood donation, menstruation perception, and preferred menstrual hygiene product. Women rated their period experience better after being made aware of the ability to donate menstrual blood, meaning MenSC therapy can be beneficial for donors as well as patients. Conclusions: Considering women's attitudes to MenSC and donation of menstrual blood, the future of MenSC therapy is positive; women are generally willing to donate menstrual blood, independent of age, perception of periods, and history of childbirth and blood donation.

SDF-1/CXCR4 axis enhances the immunomodulation of human endometrial regenerative cells in alleviating experimental colitis

Endometrial regenerative cells (ERCs) are a new type of mesenchymal-like stromal cells, and their therapeutic potential has been tested in a variety of disease models. SDF-1/CXCR4 axis plays a chemotaxis role in stem/stromal cell migration. The aim of the present study was to investigate the role of SDF-1/CXCR4 axis in the immunomodulation of ERCs on the experimental colitis. The immunomodulation of ERCs in the presence or absence of pretreatment of SDF-1 or AMD3100 was examined in both in vitro cell culture system and dextran sulphate sodium-induced colitis in mice. The results showed that SDF-1 increased the expression of CXCR4 on the surface of ERCs. As compared with normal ERCs, the SDF-1-treated, CXCR4 high-expressing ERCs more significantly suppressed dendritic cell population as well as stimulated both type 2 macrophages and regulatory T cells in vitro and in vivo. Meanwhile, SDF-1-pretreated ERCs increased the generation of anti-inflammatory factors (e.g., IL-4, IL-10) and decreased the pro-inflammatory factors (e.g., IL-6, TNF-α). In addition, SDF-1-pretreated CM-Dil-labeled ERCs were found to engraft to injured colon. Our results may suggest that an SDF-1-induced high level of CXCR4 expression enhances the immunomodulation of ERCs in alleviating experimental colitis in mice.

Dissecting the Pharmacodynamics and Pharmacokinetics of MSCs to Overcome Limitations in Their Clinical Translation

Recently, mesenchymal stromal stem cells (MSCs) have been proposed as therapeutic agents because of their promising preclinical features and good safety profile. However, their introduction into clinical practice has been associated with a suboptimal therapeutic profile. In this review, we address the biodistribution of MSCs in preclinical studies with a focus on the current understanding of the pharmacodynamics (PD) and pharmacokinetics (PK) of MSCs as key aspects to overcome unsatisfactory clinical benefits of MSC application. Beginning with evidence of MSC biodistribution and highlighting PK and PD factors, a new PK-PD model is also proposed. According to this theory, MSCs and their released factors are key players in PK, and the efficacy biomarkers are considered relevant for PD in more predictive preclinical investigations. Accounting for the PK-PD relationship in MSC translational research and proposing new models combined with better biodistribution studies could allow realization of the promise of more robust MSC clinical translation.

Stem Cells and Endometrial Regeneration: From Basic Research to Clinical Trial

Monthly changes in the endometrial cycle indicate the presence of endometrial stem cells. In recent years, various stem cells that exist in the endometrium have been identified and characterized. Additionally, many studies have shown that Bone Marrow Mesenchymal Stem Cells (BM-MSCs) provide an alternative source for regenerating the endometrium and repairing endometrial injury. This review discusses the origin of endometrial stem cells, the characteristics and main biomarkers among five types of putative endometrial stem cells, applications of endometrium-derived stem cells and menstrual blood-derived stem cells, the association between BM-MSCs and endometrial stem cells, and progress in repairing endometrial injury.

The immunomodulatory activity of extracellular vesicles derived from endometrial mesenchymal stem cells on CD4+ T cells is partially mediated by TGFbeta

Endometrial mesenchymal stem cells (endMSCs) reside in the basal and functional layer of human endometrium and participate in tissue remodelling, which is required for maintaining the regenerative capacity of the endometrium. The endMSCs are multipotent stem cells and exhibit immunomodulatory effects. This paper aimed to evaluate the regulatory effects of extracellular vesicles derived from endMSCs (EV-endMSCs) in the setting of T cell activation. In vitro stimulations of lymphocytes were performed in the presence of EV-endMSCs. These in vitro-stimulated lymphocytes were functionally and phenotypically characterized to distinguish CD4+ and CD8+ T cell differentiation subsets. Moreover, the inhibition of TGFβ was performed with neutralizing antibodies. The phenotype and nanoparticle tracking analysis of the EV-endMSCs demonstrated that they are similar in terms of size distribution to other mesenchymal stem cells-derived exosomes. The in vitro assays showed an immunomodulatory potential of these vesicles to counteract the differentiation of CD4+ T cells. The quantification of active TGFβ in EV-endMSCs was found to be very high when compared with extracellular vesicles-free concentrated supernatants. Finally, the neutralization of TGFβ significantly attenuated the immunomodulatory activity of EV-endMSCs. In summary, this is the first report demonstrating that EV-endMSCs exhibit a potent inhibitory effect against CD4+ T cell activation, which is partially mediated by TGFβ signalling.

Allogeneic cell therapy using umbilical cord MSCs on collagen scaffolds for patients with recurrent uterine adhesion: a phase I clinical trial

BACKGROUND

Intrauterine adhesions (IUA) are the most common cause of uterine infertility and are caused by endometrium fibrotic regeneration following severe damage to the endometrium. Although current stem cell treatment options using different types of autologous stem cells have exhibited some beneficial outcomes in IUA patients, the reported drawbacks include variable therapeutic efficacies, invasiveness and treatment unavailability. Therefore, the development of new therapeutic stem cell treatments is critical to improving clinical outcomes.

METHODS

Twenty-six patients who suffered from infertility caused by recurrent IUA were enrolled in this prospective, non-controlled, phase I clinical trial with a 30-month follow-up. During the procedure, 1 × 107 umbilical cord-derived mesenchymal stromal cells (UC-MSCs), loaded onto a collagen scaffold, were transplanted into the uterine cavity following an adhesion separation procedure. Medical history, physical examination, endometrial thickness, intrauterine adhesion score and the biological molecules related to endometrial proliferation and differentiation were assessed both before and 3 months after cell therapy.

RESULTS

No treatment-related serious adverse events were found. Three months after the operation, the average maximum endometrial thickness in patients increased, and the intrauterine adhesion score decreased compared to those before the treatment. A histological study showed the upregulation of ERα (estrogen receptor α), vimentin, Ki67 and vWF (von Willebrand factor) expression levels and the downregulation of ΔNP63 expression level, which indicates an improvement in endometrial proliferation, differentiation and neovascularization following treatment. DNA short tandem repeat (STR) analysis showed that the regenerated endometrium contained patient DNA only. By the end of the 30-month follow-up period, ten of the 26 patients had become pregnant, and eight of them had delivered live babies with no obvious birth defects and without placental complications, one patient in the third trimester of pregnancy, and one had a spontaneous abortion at 7 weeks.

CONCLUSIONS

Transplanting clinical-grade UC-MSCs loaded onto a degradable collagen scaffold into the uterine cavity of patients with recurrent IUA following adhesiolysis surgery is a safety and effective therapeutic method.

TRIAL REGISTRATION

Clinicaltrials.gov . NCT02313415 , Registered December 6, 2014.

Murine embryos exposed to human endometrial MSCs-derived extracellular vesicles exhibit higher VEGF/PDGF AA release, increased blastomere count and hatching rates

Endometrial Mesenchymal Stromal Cells (endMSCs) are multipotent cells with immunomodulatory and pro-regenerative activity which is mainly mediated by a paracrine effect. The exosomes released by MSCs have become a promising therapeutic tool for the treatment of immune-mediated diseases. More specifically, extracellular vesicles derived from endMSCs (EV-endMSCs) have demonstrated a cardioprotective effect through the release of anti-apoptotic and pro-angiogenic factors. Here we hypothesize that EV-endMSCs may be used as a co-adjuvant to improve in vitro fertilization outcomes and embryo quality. Firstly, endMSCs and EV-endMSCs were isolated and phenotypically characterized for in vitro assays. Then, in vitro studies were performed on murine embryos co-cultured with EV-endMSCs at different concentrations. Our results firstly demonstrated a significant increase on the total blastomere count of expanded murine blastocysts. Moreover, EV-endMSCs triggered the release of pro-angiogenic molecules from embryos demonstrating an EV-endMSCs concentration-dependent increase of VEGF and PDGF-AA. The release of VEGF and PDGF-AA by the embryos may indicate that the beneficial effect of EV-endMSCs could be mediating not only an increase in the blastocyst’s total cell number, but also may promote endometrial angiogenesis, vascularization, differentiation and tissue remodeling. In summary, these results could be relevant for assisted reproduction being the first report describing the beneficial effect of human EV-endMSCs on embryo development.

Mesenchymal endometrial stem/stromal cells for hard tissue engineering: a review of in vitro and in vivo evidence

Hard tissues including teeth, bone and cartilage have inability or poor capacity to self-renew, especially in large defects. Therefore, repair of damages in these tissues represents a huge challenge in the medical field today. Hard tissue engineering commonly utilizes different stem cell sources as a promising strategy for treating bone, cartilages and tooth defects or disorders. Decades ago, researchers successfully isolated and identified endometrial mesenchymal stem/stromal cells (EnSCs) and discovered their multidifferentiation potential. Current studies suggest that EnSCs have significant advantages compared with stem cells derived from other tissues. In this review article, we summarize the current in vitro and in vivo studies that utilize EnSCs or menstrual blood-derived stem cells for differentiation to osteoblasts, odontoblasts or chondroblasts in an effort to realize the potential of these cells in hard tissues regeneration.

Stromal Cell-Derived Factor-1 Mediates Cardiac Allograft Tolerance Induced by Human Endometrial Regenerative Cell-Based Therapy

Endometrial regenerative cells (ERCs) are mesenchymal-like stromal cells, and their therapeutic potential has been tested in the prevention of renal ischemic reperfusion injury, acute liver injury, ulcerative colitis, and immunosuppression. However, their potential in the induction of transplant tolerance has not been investigated. The present study was undertaken to investigate the efficacy of ERCs in inducing cardiac allograft tolerance and the function of stromal cell-derived factor-1 (SDF-1) in the ERC-mediated immunoregulation. The inhibitory efficacy of human ERCs in the presence or absence of rapamycin was examined in both mouse cardiac allograft models between BALB/c (H-2^d ) donors and C57BL/6 (H-2^b ) recipients and in vitro cocultured splenocytes. AMD3100 was used to inhibit the function of SDF-1. Intragraft antibody (IgG and IgM) deposition and immune cell (CD4⁺ and CD8⁺ ) infiltration were measured by immunohistochemical staining, and splenocyte phenotypes were determined by fluorescence-activated cell sorting analysis. The results showed that ERC-based therapy induced donor-specific allograft tolerance, and functionally inhibiting SDF-1 resulted in severe allograft rejection. The negative effects of inhibiting SDF-1 on allograft survival were correlated with increased levels of intragraft antibodies and infiltrating immune cells, and also with reduced levels of regulatory immune cells including MHC class II^low CD86^low CD40^low dendritic cells, CD68⁺ CD206⁺ macrophages, CD4⁺ CD25⁺ Foxp3⁺ T cells, and CD1d^high CD5^high CD83^low IL-10^high B cells both in vivo and in vitro. These data showed that human ERC-based therapy induces cardiac allograft tolerance in mice, which is associated with SDF-1 activity, suggesting that SDF-1 mediates the immunosuppression of ERC-based therapy for the induction of transplant tolerance. Stem Cells Translational Medicine 2017;6:1997-2008.

Oncolytic Adenovirus-Loaded Menstrual Blood Stem Cells Overcome the Blockade of Viral Activity Exerted by Ovarian Cancer Ascites

Patients with ovarian cancer present peritoneal ascites at recurrence as a marker of disseminated disease and dismal prognosis. Oncolytic immunotherapy is an emerging approach for the treatment of disseminated cancer. In the present work, we constructed a novel oncolytic adenovirus, AR2011, to target malignant ovarian tumors. AR2011 exhibited a clear lytic effect in vitro in human ovarian cancer cell lines and malignant cells obtained from ascitic fluids (AFs) of patients with ovarian cancer. AR2011 activity was neutralized by antibodies present in 31 samples of patient-derived AFs. However, this blockade was overridden by preloading menstrual blood stem cells (MenSCs) with AR2011 (MenSC-AR), since AFs exerted no in vitro inhibitory effect on viral lytic activity under these conditions. Moreover, soluble factors present in AFs act as MenSC chemoattractants. MenSC-AR treatment of nude mice carrying established peritoneal carcinomatosis following administration of human ovarian cancer cells was able to inhibit tumor growth at levels similar to those observed with AR2011 alone. This study demonstrates that MenSCs can be used to override the blockade that AFs exert on viral oncolytic effects.

Manufacturing Differences Affect Human Bone Marrow Stromal Cell Characteristics and Function: Comparison of Production Methods and Products from Multiple Centers

Human bone marrow stromal cells (BMSCs, also known as bone marrow-derived mesenchymal stem cells) are manufactured using many different methods, but little is known about the spectrum of manufacturing methods used and their effects on BMSC characteristics and function. Seven centers using, and one developing, Good Manufacturing Practices (GMP) processes were surveyed as to their production methods. Among the seven centers, all used marrow aspirates as the starting material, but no two centers used the same manufacturing methods. Two to four BMSC lots from each center were compared using global gene expression. Among the twenty-four BMSC lots from the eight centers intra-center transcriptome variability was low and similar among centers. Principal component analysis and unsupervised hierarchical clustering analysis separated all the lots from five centers into five distinct clusters. BMSCs from six of the eight centers were tested for their ability to form bone and support hematopoiesis by in vivo transplantation (defining features of BMSCs). Those from all six centers tested formed bone, but the quantity formed was highly variable and BMSCs from only three centers supported hematopoiesis. These results show that differences in manufacturing resulted in variable BMSC characteristics including their ability to form bone and support hematopoiesis.

Isolation, proliferation and characterization of endometrial canine stem cells

In the last decade, progenitor cells isolated from dissociated endometrial tissue have been the subject of many studies in several animal species. Recently, endometrial cells showing characteristics of mesenchymal stem cells (MSC) have been demonstrated in human, pig and cow uterine tissue samples. The aim of this study was the isolation and characterization of stromal cells from the endometrium of healthy bitches, a tissue that after elective surgery is routinely discarded. Multipotent stromal cells could be isolated from all bitches enrolled in the study (n = 7). The multipotency of cells was demonstrated by their capacity to differentiate into adipocytic, osteocytic and chondrocytic lineages. Clonogenicity and cell proliferation ability were also tested. Furthermore, gene expression analysis by RT-PCR was used to compare the expression of a set of genes (CD44, CD29, CD34, CD45, CD90, CD13, CD133, CD73, CD31 CD105, Oct4) with adipose tissue-derived MSC. Stromal cells isolated from uterine endometrium showed similar morphology, ability of subculture and plasticity, and also expressed a panel of genes comparable with adipose tissue-derived MSC. These data suggest that endometrial stromal cells fulfil the basic criteria proposed by the "Mesenchymal and Tissue Stem Cell Committee of the International Society for Cellular Therapy" for the identification of mesenchymal stem cells. Although endometrial mesenchymal stem cells (EnMSC) showed a lower replicative ability in comparison with adipose tissue-derived MSC, they could be considered a cell therapeutic agent alternative to adipose tissue or bone marrow-derived MSC in dog.

In vitro differentiation of endometrial regenerative cells into smooth muscle cells: Α potential approach for the management of pelvic organ prolapse

Pelvic organ prolapse (POP), is a common condition in parous women. Synthetic mesh was once considered to be the standard of care; however, the use of synthetic mesh is limited by severe complications, thus creating a need for novel approaches. The application of cell-based therapy with stem cells may be an ideal alternative, and specifically for vaginal prolapse. Abnormalities in vaginal smooth muscle (SM) play a role in the pathogenesis of POP, indicating that smooth muscle cells (SMCs) may be a potential therapeutic target. Endometrial regenerative cells (ERCs) are an easily accessible, readily available source of adult stem cells. In the present study, ERCs were obtained from human menstrual blood, and phase contrast microscopy and flow cytometry were performed to characterize the morphology and phenotype of the ERCs. SMC differentiation was induced by a transforming growth factor β1-based medium, and the induction conditions were optimized. We defined the SMC characteristics of the induced cells with regard to morphology and marker expression using transmission electron microscopy, western blot analysis, immunocytofluorescence and RT-PCR. Examining the expression of the components of the Smad pathway and phosphorylated Smad2 and Smad3 by western blot analysis, RT-PCR and quantitative PCR demonstrated that the 'TGFBR2/ALK5/Smad2 and Smad3' pathway is involved, and both Smad2 and Smad3 participated in SMC differentiation. Taken together, these findings indicate that ERCs may be a promising cell source for cellular therapy aimed at modulating SM function in the vagina wall and pelvic floor in order to treat POP.

Menstrual Blood-Derived Stem Cells: In Vitro and In Vivo Characterization of Functional Effects

Accumulating evidence has demonstrated that menstrual blood stands as a viable source of stem cells. Menstrual blood-derived stem cells (MenSCs) are morphologically and functionally similar to cells directly extracted from the endometrium, and present dual expression of mesenchymal and embryonic cell markers, thus becoming interesting tools for regenerative medicine. Functional reports show higher proliferative and self-renewal capacities than bone marrow-derived stem cells, as well as successful differentiation into hepatocyte-like cells, glial-like cells, endometrial stroma-like cells, among others. Moreover, menstrual blood stem cells may be used with increased efficiency in reprogramming techniques for induced Pluripotent Stem cell (iPS) generation. Experimental studies have shown successful treatment of stroke, colitis, limb ischemia, coronary disease, Duchenne's muscular atrophy and streptozotocin-induced type 1 diabetes animal models with MenSCs. As we envision an off-the-shelf product for cell therapy, cryopreserved MenSCs appear as a feasible clinical product. Clinical applications, although still very limited, have great potential and ongoing studies should be disclosed in the near future.

Endometrial stem/progenitor cells: the first 10 years

BACKGROUND

The existence of stem/progenitor cells in the endometrium was postulated many years ago, but the first functional evidence was only published in 2004. The identification of rare epithelial and stromal populations of clonogenic cells in human endometrium has opened an active area of research on endometrial stem/progenitor cells in the subsequent 10 years.

METHODS

The published literature was searched using the PubMed database with the search terms ‘endometrial stem cells and menstrual blood stem cells' until December 2014.

RESULTS

Endometrial epithelial stem/progenitor cells have been identified as clonogenic cells in human and as label-retaining or CD44⁺ cells in mouse endometrium, but their characterization has been modest. In contrast, endometrial mesenchymal stem/stromal cells (MSCs) have been well characterized and show similar properties to bone marrow MSCs. Specific markers for their enrichment have been identified, CD146⁺PDGFRβ⁺ (platelet-derived growth factor receptor beta) and SUSD2⁺ (sushi domain containing-2), which detected their perivascular location and likely pericyte identity in endometrial basalis and functionalis vessels. Transcriptomics and secretomics of SUSD2⁺ cells confirm their perivascular phenotype. Stromal fibroblasts cultured from endometrial tissue or menstrual blood also have some MSC characteristics and demonstrate broad multilineage differentiation potential for mesodermal, endodermal and ectodermal lineages, indicating their plasticity. Side population (SP) cells are a mixed population, although predominantly vascular cells, which exhibit adult stem cell properties, including tissue reconstitution. There is some evidence that bone marrow cells contribute a small population of endometrial epithelial and stromal cells. The discovery of specific markers for endometrial stem/progenitor cells has enabled the examination of their role in endometrial proliferative disorders, including endometriosis, adenomyosis and Asherman's syndrome. Endometrial MSCs (eMSCs) and menstrual blood stromal fibroblasts are an attractive source of MSCs for regenerative medicine because of their relative ease of acquisition with minimal morbidity. Their homologous and non-homologous use as autologous and allogeneic cells for therapeutic purposes is currently being assessed in preclinical animal models of pelvic organ prolapse and phase I/II clinical trials for cardiac failure. eMSCs and stromal fibroblasts also exhibit non-stem cell-associated immunomodulatory and anti-inflammatory properties, further emphasizing their desirable properties for cell-based therapies.

CONCLUSIONS

Much has been learnt about endometrial stem/progenitor cells in the 10 years since their discovery, although several unresolved issues remain. These include rationalizing the terminology and diagnostic characteristics used for distinguishing perivascular stem/progenitor cells from stromal fibroblasts, which also have considerable differentiation potential. The hierarchical relationship between clonogenic epithelial progenitor cells, endometrial and decidual SP cells, CD146⁺PDGFR-β⁺ and SUSD2⁺ cells and menstrual blood stromal fibroblasts still needs to be resolved. Developing more genetic animal models for investigating the role of endometrial stem/progenitor cells in endometrial disorders is required, as well as elucidating which bone marrow cells contribute to endometrial tissue. Deep sequencing and epigenetic profiling of enriched populations of endometrial stem/progenitor cells and their differentiated progeny at the population and single-cell level will shed new light on the regulation and function of endometrial stem/progenitor cells.

Human bone marrow stromal cell confluence: effects on cell characteristics and methods of assessment

BACKGROUND AIMS

Ex vivo expansion and serial passage of human bone marrow stromal cells (BMSCs, also known as bone marrow-derived mesenchymal stem cells) is required to obtain sufficient quantities for clinical therapy. The BMSC confluence criteria used to determine passage and harvest timing vary widely, and the impact of confluence on BMSC properties remains controversial. The effects of confluence on BMSC properties were studied and confluence-associated markers were identified.

METHODS

BMSC characteristics were analyzed as they grew from 50% to 100% confluence, including viability, population doubling time, apoptosis, colony formation, immunosuppression, surface marker expression, global gene expression and microRNA expression. In addition, culture supernatant protein, glucose, lactate and pH levels were analyzed.

RESULTS

Confluence-dependent changes were detected in the expression of several cell surface markers: 39 culture supernatant proteins, 26 microRNAs and 2078 genes. Many of these surface markers, proteins, microRNAs and genes have been reported to be important in BMSC function. The pigment epithelium-derived factor/vascular endothelial growth factor ratio increased with confluence, but 80% and 100% confluent BMSCs demonstrated a similar level of immunosuppression of mixed lymphocyte reactions. In addition, changes in lactate and glucose levels correlated with BMSC density.

CONCLUSIONS

BMSC characteristics change as confluence increases. 100% confluent BMSCs may have compromised pro-angiogenesis properties but may retain their immunomodulatory properties. Supernatant lactate and glucose levels can be used to estimate confluence and ensure consistency in passage and harvest timing. Flow cytometry or microRNA expression can be used to confirm that the BMSCs have been harvested at the appropriate confluence.

Somatic stem cells and their dysfunction in endometriosis

Emerging evidence indicates that somatic stem cells (SSCs) of different types prominently contribute to endometrium-associated disorders such as endometriosis. We reviewed the pertinent studies available on PubMed, published in English language until December 2014 and focused on the involvement of SSCs in the pathogenesis of this common gynecological disease. A concise summary of the data obtained from in vitro experiments, animal models, and human tissue analyses provides insights into the SSC dysregulation in endometriotic lesions. In addition, a set of research results is presented supporting that SSC-targeting, in combination with hormonal therapy, may result in improved control of the disease, while a more in-depth characterization of endometriosis SSCs may contribute to the development of early-disease diagnostic tests with increased sensitivity and specificity. Key message: Seemingly essential for the establishment and progression of endometriotic lesions, dysregulated SSCs, and associated molecular alterations hold a promise as potential endometriosis markers and therapeutic targets.

Endometrial stem cell transplantation in MPTP- exposed primates: an alternative cell source for treatment of Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disease caused by the loss of dopaminergic neurons in the substantia nigra. Cell-replacement therapies have emerged as a promising strategy to slow down or replace neuronal loss. Compared to other stem cell types, endometrium-derived stem cells (EDSCs) are an attractive source of stem cells for cellular therapies because of their ease of collection and vast differentiation potential. Here we demonstrate that endometrium-derived stem cells may be transplanted into an MPTP exposed monkey model of PD. After injection into the striatum, endometrium-derived stem cells engrafted, exhibited neuron-like morphology, expressed tyrosine hydroxylase (TH) and increased the numbers of TH positive cells on the transplanted side and dopamine metabolite concentrations in vivo. Our results suggest that endometrium-derived stem cells may provide a therapeutic benefit in the primate model of PD and may be used in stem cell based therapies.

Differentiation of human CD146-positive endometrial stem cells to adipogenic-, osteogenic-, neural progenitor-, and glial-like cells

The aim of this study was to investigate the potential differentiation of CD146(+) endometrial stem cells to several lineages. Endometrial stromal cells were cultured using Dulbecco's modified Eagle's medium/Hams F-12 (DMEM/F-12) and were passaged every 7-10 d when cultures reached 80-100% of confluency. The immunophenotypes of single endometrial cells were analyzed using flow cytometry at fourth passage. Then the CD146(+) cells were sorted using magnetic-activated cell sorting, and they were cultured and analyzed for in vitro differentiation to several lineages. Detection of adipocyte- and osteocyte-like cells were assessed by oil red O and alizarin red staining, respectively. For detection of neural progenitor and oligodendrocyte-like cells, the cells were immunostained by neurofilament 68 and oligo2, respectively. The rates of CD90, CD105, CD146, CD31, CD34, and CD9 of cultured endometrial cells were 94.98 ± 3%, 95.77 ± 2.5%, 27.61 ± 2%, 0.79 ± 0.05%, 1.43 ± 0.1%, and 1.01 ± 0.06%, respectively. CD146(+) cells were isolated to high purity. CD146(+)-differentiated cells to adipogenic cell with typical lipid-rich vacuoles and osteogenic cells were observed and confirmed their mesenchymal origin. They also differentiated into neural progenitor and glial differentiation by retinoic acid, basic fibroblast growth factor, and epidermal growth factor signaling molecules, respectively, and confirmed by neurofilament 68 and oligo2 immunocytochemistry. The efficiency of differentiation to neural progenitor and oligodendrocyte-like cells was 90 ± 3.4% and 79 ± 2.8%, respectively. This study showed that CD146(+) cells from human endometrium after in vitro cultivation can differentiate into adipogenic-, osteogenic-, neural progenitor-, and glial-like cells. They may provide available alternative source of stem cells for future cell-based therapies and tissue engineering applications.

Bone marrow skeletal stem/progenitor cell defects in dyskeratosis congenita and telomere biology disorders

Dyskeratosis congenita (DC) is an inherited multisystem disorder, characterized by oral leukoplakia, nail dystrophy, and abnormal skin pigmentation, as well as high rates of bone marrow (BM) failure, solid tumors, and other medical problems such as osteopenia. DC and telomere biology disorders (collectively referred to as TBD here) are caused by germline mutations in telomere biology genes leading to very short telomeres and limited proliferative potential of hematopoietic stem cells. We found that skeletal stem cells (SSCs) within the BM stromal cell population (BMSCs, also known as BM-derived mesenchymal stem cells), may contribute to the hematologic phenotype. TBD-BMSCs exhibited reduced clonogenicity, spontaneous differentiation into adipocytes and fibrotic cells, and increased senescence in vitro. Upon in vivo transplantation into mice, TBD-BMSCs failed to form bone or support hematopoiesis, unlike normal BMSCs. TERC reduction (a TBD-associated gene) in normal BMSCs by small interfering TERC-RNA (siTERC-RNA) recapitulated the TBD-BMSC phenotype by reducing proliferation and secondary colony-forming efficiency, and by accelerating senescence in vitro. Microarray profiles of control and siTERC-BMSCs showed decreased hematopoietic factors at the messenger RNA level and decreased secretion of factors at the protein level. These findings are consistent with defects in SSCs/BMSCs contributing to BM failure in TBD.

Menstrual blood-derived stromal stem cells inhibit optimal generation and maturation of human monocyte-derived dendritic cells

INTRODUCTION

Menstrual blood stromal stem Cells (MenSCs) have shown promising potential for future clinical settings. Nonetheless, data regarding their interaction with immune cells is still scarce. Here, we investigated whether MenSCs could affect the generation and/or maturation of human blood monocyte-derived dendritic cells (DCs).

MATERIALS AND METHODS

MenSCs were isolated from menstrual blood of normal women through culture of adherent mononuclear cells. Magnetically-isolated peripheral blood monocytes were differentiated toward immature DCs (iDC) and mature DCs (mDCs) in the presence or absence of MenSCs. Monocyte-derived cells were assessed for the percentage of monocyte-, iDC-, and mDC-specific markers as well as the expression of costimulatory molecules. IL-6 and IL-10 levels were also determined in supernatants of MenSC-monocytes cocultures.

RESULTS

Optimal phenotypic differentiation of monocytes into iDCs was inhibited upon coculture with MenSCs. Moreover, higher levels of IL-6 and IL-10 were detected in these settings. Even though addition of MenSCs to iDC cultures could not prevent iDC maturation, coculture of MenSCs with monocytes from the beginning of differentiation process could effectively hinder generation of fully mature DCs.

CONCLUSION

This is the first study to address the inhibitory impact of MenSCs on generation and maturation of DCs. IL-6 and IL-10 could be partly held responsible for this effect. Given the central roles of DCs in regulation of immune responses, these results highlight the importance of further research on the potential modulatory impacts of MenSCs, as rather easily accessible and expandable stem cells, on the immune system-related cells.

Endometrial stem cells in regenerative medicine

First described in 2004, endometrial stem cells (EnSCs) are adult stem cells isolated from the endometrial tissue. EnSCs comprise of a population of epithelial stem cells, mesenchymal stem cells, and side population stem cells. When secreted in the menstrual blood, they are termed menstrual stem cells or endometrial regenerative cells. Mounting evidence suggests that EnSCs can be utilized in regenerative medicine. EnSCs can be used as immuno-modulatory agents to attenuate inflammation, are implicated in angiogenesis and vascularization during tissue regeneration, and can also be reprogrammed into induced pluripotent stem cells. Furthermore, EnSCs can be used in tissue engineering applications and there are several clinical trials currently in place to ascertain the therapeutic potential of EnSCs. This review highlights the progress made in EnSC research, describing their mesodermal, ectodermal, and endodermal potentials both in vitro and in vivo.

Innate immune system and preeclampsia

Normal pregnancy is considered as a Th2 type immunological state that favors an immune-tolerance environment in order to prevent fetal rejection. Preeclampsia (PE) has been classically described as a Th1/Th2 imbalance; however, the Th1/Th2 paradigm has proven insufficient to fully explain the functional and molecular changes observed during normal/pathological pregnancies. Recent studies have expanded the Th1/Th2 into a Th1/Th2/Th17 and regulatory T-cells paradigm and where dendritic cells could have a crucial role. Recently, some evidence has emerged supporting the idea that mesenchymal stem cells might be part of the feto-maternal tolerance environment. This review will discuss the involvement of the innate immune system in the establishment of a physiological environment that favors pregnancy and possible alterations related to the development of PE.

Thermogel nanofiber induces human endometrial-derived stromal cells to neural differentiation: In vitro and in vivo studies in rat

Spinal cord injury (SCI) in humans remains a devastating and incurable disorder. The use of Matrigel, a hydrogel-mimicking extracellular matrix, has been suggested as a scaffold for spinal cord regeneration. Human endometrial-derived stromal cells (hEnSCs) are abundant and available in adult stem cells with low immunological incompatibility, which could be considered for cell replacement therapy. The purpose of this study was to investigate the role of Matrigel in neural differentiation of hEnSCs in vitro and assess the supportive effects of this hydrogel in an animal model of SCI. hEnSCs were isolated and encapsulated into nanofibrous thermogel and cell viability and cell membrane damage were assessed. Encapsulated hEnSCs into Matrigel were treated with neural differentiation medium for 21 days, and then neural genes and protein markers were analyzed using real time-PCR and immunocytochemistry. Matrigel was implanted into rats with SCI and followed for 42 days using a behavioral test. Our study revealed a higher cell viability and neural differentiation in the level of genes and proteins as well as lower cell membrane damage. Substantial recoveries of motor function were observed in animals receiving the Matrigel treatment. The treatment with Matrigel, nanofibrous scaffold, produced beneficial effects on functional recovery following SCI in rats, possibly via assimilation to cytoskeleton fiber, high surface/volume ratio, spatial interconnectivity and containing some adhesive molecules and growth factors, enhancement of anti-inflammation, anti-astrogliosis, neuronal extension, and neuronal regeneration effects.

Establishing a bone marrow stromal cell transplant program at the National Institutes of Health Clinical Center

A repository of cryopreserved bone marrow stromal cell (BMSC) products prepared from marrow aspirates of healthy subjects has been created and is being used to treat patients with inflammatory bowel disease, cardiovascular disease, and acute graft-versus-host disease following allogeneic hematopoietic stem cell transplantation. New methods of manufacturing BMSCs are being investigated including the use of an automated bioreactor for BMSC expansion and the replacement of fetal bovine serum with human platelet lysate as a media supplement. Efforts are also being made to identify markers that can be used to assess the potency of BMSCs.

The effect of Noggin supplementation in Matrigel nanofiber-based cell culture system for derivation of neural-like cells from human endometrial-derived stromal cells

A very important obstacle in axonal regeneration after spinal cord injury is astroglial scaring. Noggin as bone morphogenic protein inhibitor plays a critical role in decreasing GFAP(+) cells and reducing the number of astrocytes in the site of injury. Human endometrial-derived stromal cells (hEnSCs) were isolated and cultured in two different neural inductive mediums consisting of neural progenitor maintenance medium (NPMM)/BDNF or NPMM/BDNF/Noggin in Matrigel 3D cell culture. Neural expression markers were investigated at the mRNA and protein level by real-time PCR and immunocytochemistry, respectively. The results showed that Noggin supplementation was able to increase the expression of Nestin, Tuj-1, and NF, whereas the expressions of GFAP, Bcl2, and Olig2 were decreased. In addition, DAPI staining demonstrated that lighter blue chromatin agreed with our observation of lower level of Bcl2 expression in the Noggin protocol in which over-expression of Bcl2 gene did not induce higher neurogenesis in poor Noggin medium. Our findings clearly demonstrated the neural differentiation potential of hEnSC in Matrigel and also Noggin supplementation was able to inhibit astrocyte formation.

Regenerating endometrium from stem/progenitor cells: is it abnormal in endometriosis, Asherman's syndrome and infertility?

PURPOSE OF REVIEW

Stem/progenitor cells are present in human and rodent endometrium and have a key role in endometrial regeneration in normal cycling and after parturition. We review emerging evidence of multiple types of endometrial stem/progenitor cells, and that abnormalities in their location and function may contribute to endometriosis.

RECENT FINDINGS

Candidate human endometrial stem/progenitors have been identified as clonogenic, Side Population and possessing tissue reconstitution activity. Markers have been identified for human endometrial mesenchymal stem cells, showing their perivascular location in functionalis and basalis endometrium. Human embryonic stem cells can be induced to develop endometrial epithelium, recapitulating endometrial development. In rodent studies, endometrial stem/progenitor cells were identified as label-retaining cells and their role in endometrial repair and regeneration revealed, perhaps via mesenchymal to epithelial transition. Studies of Wnt signalling in the regulation of endometrial stem/progenitor cells may yield insights into their function in endometrial regeneration. Stem/progenitor cells can be isolated from endometrial biopsy or menstrual blood and may be used autologously to regenerate endometrium in Asherman's syndrome.

SUMMARY

There is much to be learnt about endometrial stem/progenitor cell biology and their role in endometriosis. Endometrial stem/progenitor cells hold great promise for new treatments for infertility associated disorders, including thin dysfunctional endometrium and Asherman's syndrome.

Intra-subject variability in human bone marrow stromal cell (BMSC) replicative senescence: molecular changes associated with BMSC senescence

The outcomes of clinical trials using bone marrow stromal cell (BMSC) are variable; the degree of the expansion of BMSCs during clinical manufacturing may contribute to this variability since cell expansion is limited by senescence. Human BMSCs from aspirates of healthy subjects were subcultured serially until cell growth stopped. Phenotype and functional measurements of BMSCs from two subjects including senescence-associated beta-galactosidase staining and colony formation efficiency changed from an early to a senescence pattern at passage 6 or 7. Transcriptome analysis of 10 early and 15 late passage BMSC samples from 5 subjects revealed 2122 differentially expressed genes, which were associated with immune response, development, and cell proliferation pathways. Analysis of 57 serial BMSC samples from 7 donors revealed that the change from an early to senescent profile was variable among subjects and occurred prior to changes in phenotypes. BMSC age expressed as a percentage of maximum population doublings (PDs) was a good indicator for an early or senescence transcription signature but this measure of BMSC life span can only be calculated after expanding BMSCs to senescence. In order to find a more useful surrogate measure of BMSC age, we used a computational biology approach to identify a set of genes whose expression at each passage would predict elapsed age of BMSCs. A total of 155 genes were highly correlated with BMSC age. A least angle regression algorithm identified a set of 24 BMSC age-predictive genes. In conclusion, the onset of senescence-associated molecular changes was variable and preceded changes in other indicators of BMSC quality and senescence. The 24 BMSC age predictive genes will be useful in assessing the quality of clinical BMSC products.

Toward the use of endometrial and menstrual blood mesenchymal stem cells for cell-based therapies

INTRODUCTION

Bone marrow is a widely used source of mesenchymal stem cells (MSCs) for cell-based therapies. Recently, endometrium - the highly regenerative lining of the uterus - and menstrual blood have been identified as more accessible sources of MSCs. These uterine MSCs include two related cell types: endometrial MSCs (eMSCs) and endometrial regenerative cells (ERCs).

AREAS COVERED

The properties of eMSCs and ERCs and their application in preclinical in vitro and in vivo studies for pelvic organ prolapse, heart disorders and ischemic conditions are reviewed. Details of the first clinical Phase I and Phase II studies will be provided.

EXPERT OPINION

The authors report that eMSCs and ERCs are a readily available source of adult stem cells. Both eMSCs and ERCs fulfill the key MSC criteria and have been successfully used in preclinical models to treat various diseases. Data on clinical trials are sparse. More research is needed to determine the mechanism of action of eMSCs and ERCs in these regenerative medicine models and to determine the long-term benefits and any adverse effects after their administration.

Endometrial regenerative cells for treatment of heart failure: a new stem cell enters the clinic

Heart failure is one of the key causes of morbidity and mortality world-wide. The recent findings that regeneration is possible in the heart have made stem cell therapeutics the Holy Grail of modern cardiovascular medicine. The success of cardiac regenerative therapies hinges on the combination of an effective allogeneic “off the shelf” cell product with a practical delivery system. In 2007 Medistem discovered the Endometrial Regenerative Cell (ERC), a new mesenchymal-like stem cell. Medistem and subsequently independent groups have demonstrated that ERC are superior to bone marrow mesenchymal stem cells (MSC), the most widely used stem cell source in development. ERC possess robust expansion capability (one donor can generate 20,000 patients doses), key growth factor production and high levels of angiogenic activity. ERC have been published in the peer reviewed literature to be significantly more effect at treating animal models of heart failure (Hida et al. Stem Cells 2008).

Current methods of delivering stem cells into the heart suffer several limitations in addition to poor delivery efficiency. Surgical methods are highly invasive, and the classical catheter based techniques are limited by need for sophisticated cardiac mapping systems and risk of myocardial perforation. Medistem together with Dr. Amit Patel Director of Clinical Regenerative Medicine at University of Utah have developed a novel minimally invasive delivery method that has been demonstrated safe and effective for delivery of stem cells (Tuma et al. J Transl Med 2012). Medistem is evaluating the combination of ERC, together with our retrograde delivery procedure in a 60 heart failure patient, double blind, placebo controlled phase II trial. To date 17 patients have been dosed and preliminary analysis by the Data Safety Monitoring Board has allowed for trial continuation.

The combined use of a novel “off the shelf” cell together with a minimally invasive 30 minute delivery method provides a potentially paradigm-shifting approach to cardiac regenerative therapy.