Amniotic membrane mesenchymal stem cells can differentiate into germ cells in vitro

Functional variation among mesenchymal stem cells derived from different tissue sources

Background

Mesenchymal stem cells (MSCs) are increasingly recognized for their regenerative potential. However, their clinical application is hindered by their inherent variability, which is influenced by various factors, such as the tissue source, culture conditions, and passage number.

Methods

MSCs were sourced from clinically relevant tissues, including adipose tissue-derived MSCs (ADMSCs, n = 2), chorionic villi-derived MSCs (CMMSCs, n = 2), amniotic membrane-derived MSCs (AMMSCs, n = 3), and umbilical cord-derived MSCs (UCMSCs, n = 3). Passages included the umbilical cord at P0 (UCMSCP0, n = 2), P3 (UCMSCP3, n = 2), and P5 (UCMSCP5, n = 2) as well as the umbilical cord at P5 cultured under low-oxygen conditions (UCMSCP5L, n = 2).

Results

We observed that MSCs from different tissue origins clustered into six distinct functional subpopulations, each with varying proportions. Notably, ADMSCs exhibited a higher proportion of subpopulations associated with vascular regeneration, suggesting that they are beneficial for applications in vascular regeneration. Additionally, CMMSCs had a high proportion of subpopulations associated with reproductive processes. UCMSCP5 and UCMSCP5L had higher proportions of subpopulations related to female reproductive function than those for earlier passages. Furthermore, UCMSCP5L, cultured under low-oxygen (hypoxic) conditions, had a high proportion of subpopulations associated with pro-angiogenic characteristics, with implications for optimizing vascular regeneration.

Conclusions

This study revealed variation in the distribution of MSC subpopulations among different tissue sources, passages, and culture conditions, including differences in functions related to vascular and reproductive system regeneration. These findings hold promise for personalized regenerative medicine and may lead to more effective clinical treatments across a spectrum of medical conditions.

The Role of Retinoic Acid in Spermatogenesis and Its Application in Male Reproduction

Spermatogenesis in mammalian testes is essential for male fertility, ensuring a continuous supply of mature sperm. The testicular microenvironment finely tunes this process, with retinoic acid, an active metabolite of vitamin A, serving a pivotal role. Retinoic acid is critical for various stages, including the differentiation of spermatogonia, meiosis in spermatogenic cells, and the production of mature spermatozoa. Vitamin A deficiency halts spermatogenesis, leading to the degeneration of numerous germ cells, a condition reversible with retinoic acid supplementation. Although retinoic acid can restore fertility in some males with reproductive disorders, it does not work universally. Furthermore, high doses may adversely affect reproduction. The inconsistent outcomes of retinoid treatments in addressing infertility are linked to the incomplete understanding of the molecular mechanisms through which retinoid signaling governs spermatogenesis. In addition to the treatment of male reproductive disorders, the role of retinoic acid in spermatogenesis also provides new ideas for the development of male non-hormone contraceptives. This paper will explore three facets: the synthesis and breakdown of retinoic acid in the testes, its role in spermatogenesis, and its application in male reproduction. Our discussion aims to provide a comprehensive reference for studying the regulatory effects of retinoic acid signaling on spermatogenesis and offer insights into its use in treating male reproductive issues.

Multipotent fetal stem cells in reproductive biology research

Due to the limited accessibility of the in vivo situation, the scarcity of the human tissue, legal constraints, and ethical considerations, the underlying molecular mechanisms of disorders, such as preeclampsia, the pathological consequences of fetomaternal microchimerism, or infertility, are still not fully understood. And although substantial progress has already been made, the therapeutic strategies for reproductive system diseases are still facing limitations. In the recent years, it became more and more evident that stem cells are powerful tools for basic research in human reproduction and stem cell-based approaches moved into the center of endeavors to establish new clinical concepts. Multipotent fetal stem cells derived from the amniotic fluid, amniotic membrane, chorion leave, Wharton´s jelly, or placenta came to the fore because they are easy to acquire, are not associated with ethical concerns or covered by strict legal restrictions, and can be banked for autologous utilization later in life. Compared to adult stem cells, they exhibit a significantly higher differentiation potential and are much easier to propagate in vitro. Compared to pluripotent stem cells, they harbor less mutations, are not tumorigenic, and exhibit low immunogenicity. Studies on multipotent fetal stem cells can be invaluable to gain knowledge on the development of dysfunctional fetal cell types, to characterize the fetal stem cells migrating into the body of a pregnant woman in the context of fetomaternal microchimerism, and to obtain a more comprehensive picture of germ cell development in the course of in vitro differentiation experiments. The in vivo transplantation of fetal stem cells or their paracrine factors can mediate therapeutic effects in preeclampsia and can restore reproductive organ functions. Together with the use of fetal stem cell-derived gametes, such strategies could once help individuals, who do not develop functional gametes, to conceive genetically related children. Although there is still a long way to go, these developments regarding the usage of multipotent fetal stem cells in the clinic should continuously be accompanied by a wide and detailed ethical discussion.

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

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

Use of alginate hydrogel to improve long-term 3D culture of spermatogonial stem cells: stemness gene expression and structural features

The quality and quantity of a spermatogonial stem-cell (SSC) culture can be measured in less time using a 3D culture in a scaffold. The present study investigated stemness gene expression and the morphological and structural characterization of SSCs encapsulated in alginate. SSCs were harvested from BALB/c neonatal mice testes through two-step mechanical and enzymatic digestion. The spermatogonial populations were separated using magnetic-activated cell sorting (MACS) using an anti-Thy1 antibody and c-Kit. The SSCs then were encapsulated in alginate hydrogel. After 2 months of SSC culturing, the alginate microbeads were extracted and stained to evaluate their histological properties. Real-time polymerase chain reaction (PCR) was performed to determine the stemness gene expression. Scanning electron microscopy (SEM) was performed to evaluate the SSC morphology, density and scaffold structure. The results showed that encapsulated SSCs had decreased expression of Oct4, Sox2 and Nanos2 genes, but the expression of Nanog, Bcl6b and Plzf genes was not significantly altered. Histological examination showed that SSCs with pale nuclei and numerous nucleolus formed colonies. SEM evaluation revealed that the alginate scaffold structure preserved the SSC morphology and density for more than 60 days. Cultivation of SSCs on alginate hydrogel can affect Oct4, Sox2 and Nanos2 expression.

Mesenchymal stromal/stem cells and their exosomes for restoration of spermatogenesis in non-obstructive azoospermia: a systemic review

Stem cells have been introduced as new promising therapeutic agents in treatment of degenerative diseases because of having high differentiation potential while maintaining the ability to self-replicate and retaining features of their source cells. Among different type of cell therapies, mesenchymal stromal/stem cell (MSC) therapy is being increasingly developed as a new way to treat structural defects that need to be repaired and regenerated. Non-obstructive azoospermia (NOA) is a reproductive disease in men that causes infertility in 10% of infertile men. Based on in vitro studies, MSCs from different tissue sources have been differentiated into germ cells or gamete progenitor cells by simple methods in both male and female. On the other hand, the therapeutic effects of MSCs have been evaluated for the treatment of NOA animal models created by chemical or surgical compounds. The results of these studies confirmed successful allotransplantation or xenotransplantation of MSCs in the seminiferous tubules. As well, it has been reported that exosomes secreted by MSCs are able to induce the process of spermatogenesis in the testes of infertile animal models. Despite numerous advances in the treatment of reproductive diseases in men and women with the help of MSCs or their exosomes, no clinical trial has been terminated on the treatment of NOA. This systematic review attempts to investigate the possibility of MSC therapy for NOA in men.

Human amnion mesenchymal stem cells restore spermatogenesis in mice with busulfan-induced testis toxicity by inhibiting apoptosis and oxidative stress

Background

Before starting gonadotoxic therapies, cryopreservation of mature sperm has been proposed worldwide as a method for male fertility preservation and for enabling the conception of a healthy baby with assisted reproductive technology (ART); however, these technologies are not feasible for prepubertal boys and men with spermatogenic failure. Transplantation of mesenchymal stem cells has exhibited successful therapeutic benefits in restoring spermatogenesis via gonadal graft angiogenesis, transplanted cell clonogenesis, and disordered somatic compartment recovery. This study aimed to elucidate the fertility protective effects and the underlying mechanisms of human amnion mesenchymal stem cells (hAMSCs) against busulfan-induced testis toxicity.

Methods

An in vivo busulfan-induced testis toxicity mouse model and an in vitro busulfan-administered mouse Sertoli cell line were employed to evaluate the efficacy and mechanisms of hAMSC transplantation on male fertility preservation. The process of spermatogenesis was evaluated histologically, and the percentage of seminiferous tubules with vacuoles was evaluated by HE staining. Semen parameters were calculated by computer-assisted semen analysis. ELISA was employed to test the testosterone concentration and the levels of oxidative- and antioxidative-associated substances LDH, MDA, GR, SOD, GPx, and CAT. The rates of proliferation (Ki67), apoptosis (Annexin V), and ROS were measured by FACS. The fluorescence intensity of a marker of apoptosis (TUNEL) and a meiosis gene in spermatogenesis (SCP3) were detected by immunofluorescence assay. The expression of mRNA in germ cell-specific (GCS) genes (Dazl, Ddx4, and Miwi) and meiosis genes (Scp3, Cyclin A1, and Stra8) was tested by qPCR. The expression of antiapoptotic proteins (SURVIVIN and BCL2), apoptotic proteins (CASPASE3 and CASPASE9), GCS proteins (Dazl, Ddx4, and Miwi), and meiosis proteins (Scp3, Cyclin A1, and Stra8) was tested by western blotting.

Results

hAMSC transplantation following disruption by busulfan-induced testis toxicity restored spermatogenesis, elevating testosterone levels and enhancing testicular weight, size, and semen parameters in vivo. In addition, hAMSCs clearly ameliorated cell apoptosis, enhanced cell proliferation, repressed oxidative damage, and augmented oxidative defense in vivo and in vitro. Moreover, hAMSCs distinctly increased the expression of the GCS genes Dazl, Ddx4, and Miwi and the meiosis genes Scp3, Cyclin A1, and Stra8 in vivo.

Conclusions

hAMSCs might represent a promising tool for the use in regenerative medicine, as these cells can restore spermatogenesis in a busulfan-induced testis toxicity mouse model and facilitate activity in a busulfan-administered mouse Sertoli cell line by resisting apoptosis and oxidative stress.

Myogenic differentiation of human amniotic mesenchymal cells and its tissue repair capacity on volumetric muscle loss

Stem cell-based tissue engineering therapy is the most promising method for treating volumetric muscle loss. Human amniotic mesenchymal cells possess characteristics similar to those of embryonic stem cells. In this study, we verified the stem cell characteristics of human amniotic mesenchymal cells by the flow cytometry analysis, and osteogenic and adipogenic differentiation. Through induction with the DNA demethylating agent 5-azacytidine, human amniotic mesenchymal cells can undergo myogenic differentiation and express skeletal muscle cell-specific markers such as desmin and MyoD. The Wnt/β-catenin signaling pathway also plays an important role. After 5-azacytidine-induced human amniotic mesenchymal cells were implanted into rat tibialis anterior muscle with volumetric muscle loss, we observed increased angiogenesis and improved local tissue repair. We believe that human amniotic mesenchymal cells can serve as a potential source of cells for skeletal muscle tissue engineering.

Hedgehog pathway inhibition causes primary follicle atresia and decreases female germline stem cell proliferation capacity or stemness

Background

Follicle depletion is one of the causes of premature ovarian failure (POF) and primary ovarian insufficiency (POI). Hence, maintenance of a certain number of female germline stem cells (FGSCs) is optimal to produce oocytes and replenish the primordial follicle pool. The mechanism that regulates proliferation or stemness of FGSCs could contribute to restoring ovarian function, but it remains uncharacterized in postnatal mammalian ovaries. This study aims to investigate the mechanism by which inhibiting the activity of the hedgehog (Hh) signaling pathway regulates follicle development and FGSC proliferation.

Methods and results

To understand the role of the Hh pathway in ovarian aging, we measured Hh signaling activity at different reproductive ages and the correlation between them in physiological and pathological mice. Furthermore, we evaluated the follicle number and development and the changes in FGSC proliferation or stemness after blocking the Hh pathway in vitro and in vivo. In addition, we aimed to explain one of the mechanisms for the FGSC phenotype changes induced by treatment with the Hh pathway-specific inhibitor GANT61 via oxidative stress and apoptosis. The results show that the activity of Hh signaling is decreased in the ovaries in physiological aging and POF models, which is consistent with the trend of expression levels of the germline stem cell markers Mvh and Oct4. In vitro, blocking the Hh pathway causes follicular developmental disorders and depletes ovarian germ cells and FGSCs after treating ovaries with GANT61. The proliferation or stemness of cultured primary FGSCs is reduced when Hh activity is blocked. Our results show that the antioxidative enzyme level and the ratio of Bcl-2/Bax decrease, the expression level of caspase 3 increases, the mitochondrial membrane potential is abnormal, and ROS accumulate in this system.

Conclusions

We observed that the inhibition of the Hh signaling pathway with GANT61 could reduce primordial follicle number and decrease FGSC reproductive capacity or stemness through oxidative damage and apoptosis.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1299-5) contains supplementary material, which is available to authorized users.

Recent trends in peripheral nervous regeneration using 3D biomaterials

Mesenchymal stem cells (MSCs) owing their multipotency are known as progenitors for the regeneration of adult tissues including that of neuronal tissue. The repair and/or regeneration of traumatic nerves is still a challenging task for neurosurgeons. It is also a well-established fact that the microenvironment plays a primary role in determining the fate of stem cells to a specific lineage. In recent years, with the advent of nanotechnology and its positive influence on designing and fabrication of various 3D biomaterials have progressed to a greater extent. The production of 3D biomaterials such as nanofibers, conduits and hydrogels are providing a suitable environment for mimicking physiological niche of stem cells. These 3D biomaterials in combination with MSCs have been successfully analyzed for their potential in the regeneration of degenerative neurological disorders. This review primarily highlights the combinatorial effect of multipotent MSCs seeded on various 3D polymeric scaffolds in repair and regeneration of nervous tissue. The elaboration of MSCs from distinct sources reported so far in literature are summarized to understand their role in regeneration processes. Furthermore, we accentuate the application of 3D biomaterials especially the nanofibers, polymeric conduits, hydrogels infiltrated with MSCs harvested from distinct sources in the field of peripheral nerve regeneration studies.

Sertoli cell-mediated differentiation of bovine fetal mesenchymal stem cells into germ cell lineage using an in vitro co-culture system

In vitro gamete derivation based on differentiation of germ cells (GC) from stem cells has emerged as a potential new strategy for the treatment of male infertility. This technology also has potential applications in animal reproduction as an alternative method for dissemination of elite animal genetics, production of transgenic animals, and conservation of endangered species. Mesenchymal stem cells (MSC) are multipotent progenitor cells defined by their ability to differentiate into mesodermal lineages. Under the effect of selected bioactive factors, MSC upregulate expression of pluripotent and GC specific-markers revealing their potential for GC differentiation. In addition to the effect of trophic factors, cell-to-cell interaction with Sertoli cells (SC) may be required to guide the sequential differentiation of MSC into GC. Thus, the aim of the present study was to investigate the effect of coculture with SC on the potential for in vitro GC differentiation of bovine fetal MSC (bfMSC) derived from bone marrow (BM-MSC) and adipose tissue (AT-MSC). bfMSC were isolated from male bovine fetuses and SC were collected from adult bull testes. The effect of SC interaction with BM-MSC or AT-MSC was analyzed on the expression of pluripotent factors OCT4 and NANOG, GC genes FRAGILLIS, STELLA and VASA and male GC markers DAZL, PIWIL2, STRA8 and SCP3 at Day 14 of coculture. Flow cytometry analyses detected that the majority (95,5% ± 2.5; P < 0.05) of the isolated population of SC cultures were positive for SC-specific marker WT1. Levels of mRNA of WT1 in BM-MSC and AT-MSC were lower (P < 0.05) compared to SC; whereas, WT1 expression was not detected in bovine fetal fibroblasts (FB). Cocultures of BM-MSC and AT-MSC with SC had higher (P < 0.05) OCT4 mRNA levels compared to monocultures of BM-MSC, AT-MSC and SC. Moreover, cocultures of BM-MSC with SC had higher (P < 0.05) proportion of cells positive for Oct4 and Nanog compared to monocultures of BM-MSC and SC. Levels of mRNA of DAZL, PIWIL2 and SCP3 were upregulated in cocultures of AT-MSC with SC compared to monocultures of AT-MSC and SC. Accordingly, the proportion of cells positive for Dazl were higher (P < 0.05) in cocultures of AT-MSC with SC compared to monocultures of AT-MSC and SC. Changes in gene expression profiles during coculture of SC with AT-MSC suggest that cell-to-cell interaction or bioactive factors provided by SC may induce progression of AT-MSC into early stages of GC differentiation.

Mesenchymal Stem Cells (MSCs) Therapy for Recovery of Fertility: a Systematic Review

In recent years, the mesenchymal stem cells (MSCs) have provided the new opportunities to treat different disorders including infertility. Different studies have suggested that the MSCs have ability to differentiate into germ-like cells under specific induction conditions as well as transplantation to gonadal tissues. The aim of this systematic review was to evaluate the results obtained from different studies on MSCs therapy for promoting fertility. This search was done in PubMed and Science Direct databases using key words MSCs, infertility, therapy, germ cell, azoospermia, ovarian failure and mesenchymal stem cell. Among the more than 11,400 papers, 53 studies were considered eligible for more evaluations. The obtained results indicated that the most studies were performed on MSCs derived from bone marrow and umbilical cord as compared with the other types of MSCs. Different evaluations on animal models as well as in vitro studies supported from their role in the recovery of spermatogenesis and folliculogenesis. Although the data obtained from this systematic review are promising, but the further studies need to assess the efficiency and safety of transplantation of these cells in fertility recovery.

Induction of Human Adipose-Derived Mesenchymal Stem Cells into Germ Lineage Using Retinoic Acid

Accumulating evidence indicates that mesenchymal stem cells (MSCs) have been widely used in tissue engineering and regenerative medicine due to their multilineage differentiation potentials. Recent studies show that germ-like cells can also be derived from stem cells, such as human umbilical cord MSCs and human bone marrow MSCs in vitro. However, whether human adipose-derived MSCs (hAD-MSCs) can be induced into germ-like cells has never been reported. In this study, we isolated hAD-MSCs and confirmed that their characteristics were in accordance with that of MSCs established before. Germ cell lineage differentiation was performed by 10 μM retinoic acid (RA) treatment for 21 days. RA induction led to slender spindles and tadpole-like changes of cell morphology, and the expression of germ cell-specific markers (Oct4, Piwil2, Itgb1, SSEA-1, and Stra8) presented significant upregulation in the RA treatment group according to the polymerase chain reaction and immunofluorescence results. We first demonstrated that hAD-MSCs can differentiate into germ-like cells in vitro, which will provide theoretical and experimental basis for the clinical application of hAD-MSCs in the treatment for infertility.

Mesenchymal Stem and Progenitor Cells in Regeneration: Tissue Specificity and Regenerative Potential

It has always been an ambitious goal in medicine to repair or replace morbid tissues for regaining the organ functionality. This challenge has recently gained momentum through considerable progress in understanding the biological concept of the regenerative potential of stem cells. Routine therapeutic procedures are about to shift towards the use of biological and molecular armamentarium. The potential use of embryonic stem cells and invention of induced pluripotent stem cells raised hope for clinical regenerative purposes; however, the use of these interventions for regenerative therapy showed its dark side, as many health concerns and ethical issues arose in terms of using these cells in clinical applications. In this regard, adult stem cells climbed up to the top list of regenerative tools and mesenchymal stem cells (MSC) showed promise for regenerative cell therapy with a rather limited level of risk. MSC have been successfully isolated from various human tissues and they have been shown to offer the possibility to establish novel therapeutic interventions for a variety of hard-to-noncurable diseases. There have been many elegant studies investigating the impact of MSC in regenerative medicine. This review provides compact information on the role of stem cells, in particular, MSC in regeneration.