Enhancement of mouse germ cell-associated genes expression by injection of human umbilical cord mesenchymal stem cells into the testis of chemical-induced azoospermic mice

Management of oxidative stress for cell therapy through combinational approaches of stem cells, antioxidants, and photobiomodulation

Over the recent decades, stem cell-based therapies have been considered as a beneficial approach for the treatment of various diseases. In these types of therapies, the stem cells and their products are used as treating agents. Despite the helpful efficacy of stem cell-based therapies, there may be challenges. Oxidative stress (OS) is one of these challenges that can affect the therapeutic properties of stem cells. Therefore, it seems that employing strategies for the reduction of OS in combination with stem cell therapy can lead to better results of these therapies. Based on the available evidence, antioxidant therapy and photobiomodulation (PBM) are strategies that can regulate the OS in the cells. Antioxidant therapy is a method in which various antioxidants are used in the therapeutic processes. PBM is also the clinical application of light that gained importance in medicine. Antioxidants and PBM can regulate OS by the effect on mitochondria as an important source of OS in the cells. Considering the importance of OS in pathologic pathways and its effect on the treatment outcomes of stem cells, in the present review first the stem cell therapy and effects of OS on this type of therapy are summarized. Then, antioxidant therapy and PBM as approaches for reducing OS with a focus on mitochondrial function are discussed. Also, a novel combination treatment with the hope of achieving better and more stable outcomes in the treatment process of diseases is proposed.

Exosomes derived from umbilical cord mesenchymal stem cells ameliorate male infertility caused by busulfan in vivo and in vitro

Environmental pollution has emerged as a global concern due to its detrimental effects on human health. One of the critical aspects of this concern is the impact of environmental pollution on sperm quality in males. Male factor infertility accounts for approximately 40%- 50% of all infertility cases. Nonobstructive azoospermia (NOA) is the most severe type of male infertility. Human umbilical cord mesenchymal stem cell (hUCMSC) exosomes enhance proliferation and migration, playing crucial roles in tissue and organ injury repair. However, whether hUCMSC exosomes impacting on NOA caused by chemotherapeutic agents remains unknown. This study aimed to explore the functional restoration and mechanism of hUCMSC exosomes on busulfan-induced injury in GC-1 spg cells and ICR mouse testes. Our results revealed that hUCMSC exosomes effectively promoted the proliferation and migration of busulfan-treated GC-1 spg cells. Additionally, oxidative stress and apoptosis were significantly reduced when hUCMSC exosomes were treated. Furthermore, the injection of hUCMSC exosomes into the testes of ICR mice treated with busulfan upregulated the expression of mouse germ cell-specific genes, such as vasa, miwi, Stra8 and Dazl. Moreover, the expression of cellular junction- and cytoskeleton-related genes, including connexin 43, ICAM-1, β-catenin and androgen receptor (AR), was increased in the testicular tissues treated with exosomes. Western blot analysis demonstrated significant downregulation of apoptosis-associated proteins, such as bax and caspase-3, and upregulation of bcl-2 in the mouse testicular tissues injected with hUCMSC exosomes. Further, the spermatogenesis in the experimental group of mice injected with exosomes showed partial restoration of spermatogenesis compared to the busulfan-treated group. Collectively, these findings provide evidence for the potential clinical applications of hUCMSC exosomes in cell repair and open up new avenues for the clinical treatment of NOA.

Fertility Protection, A Novel Concept: Umbilical Cord Mesenchymal Stem Cell-Derived Exosomes Protect against Chemotherapy-Induced Testicular Cytotoxicity

Currently, there is no viable option for fertility preservation in prepubertal boys. Experimentally, controlled vitrification of testicular tissue has been evaluated and found to cause potential structural damage to the spermatogonial stem cell (SSC) niche during cryopreservation. In this report, we leveraged the regenerative effect of human umbilical cord-derived Mesenchymal stem cell exosomes (h-UCMSC-Exo) to protect against testicular damage from the cytotoxic effects of polychemotherapy (CTX). A chemotherapy-induced testicular dysfunctional model was established by CTX treatment with cyclophosphamide and Busulfan in vitro (human Sertoli cells) and in prepubescent mice. We assessed the effects of the exosomes by analyzing cell proliferation assays, molecular analysis, immunohistochemistry, body weight change, serum hormone levels, and fertility rate. Our data indicates the protective effect of h-UCMSC-Exo by preserving the SSC niche and preventing testicular damage in mice. Interestingly, mice that received multiple injections of h-UCMSC-Exo showed significantly higher fertility rates and serum testosterone levels (p < 0.01). Our study demonstrates that h-UCMSC-Exo can potentially be a novel fertility protection approach in prepubertal boys triaged for chemotherapy treatment.

Human umbilical cord mesenchymal stem cells (hUC-MSCs) alleviate paclitaxel-induced spermatogenesis defects and maintain male fertility

Chemotherapeutic drugs can cause reproductive damage by affecting sperm quality and other aspects of male fertility. Stem cells are thought to alleviate the damage caused by chemotherapy drugs and to play roles in reproductive protection and treatment. This study aimed to explore the effects of human umbilical cord mesenchymal stem cells (hUC-MSCs) on alleviating paclitaxel (PTX)-induced spermatogenesis and male fertility defects. An in vivo PTX-induced mice model was constructed to evaluate the reproductive toxicity and protective roles of hUC-MSCs in male fertility improvement. A 14 day PTX treatment regimen significantly attenuated mice spermatogenesis and sperm quality, including affecting spermatogenesis, reducing sperm counts, and decreasing sperm motility. hUC-MSCs treatment could significantly improve sperm functional indicators. Mating experiments with normal female mice and examination of embryo development at 7.5 days post-coitum (dpc) showed that hUC-MSCs restored male mouse fertility that was reduced by PTX. In IVF experiments, PTX impaired sperm fertility and blastocyst development, but hUC-MSCs treatment rescued these indicators. hUC-MSCs' protective role was also displayed through the increased expression of the fertility-related proteins HSPA2 and HSPA4L in testes with decreased expression in the PTX-treated group. These changes might be related to the PTX-induced decreases in expression of the germ cell proliferation protein PCNA and the meiosis proteins SYCP3, MLH1, and STRA8, which were restored after hUC-MSCs treatment. In the PTX-treated group, the expression of testicular antioxidant proteins SIRT1, NRF2, CAT, SOD1, and PRDX6 was significantly decreased, but hUC-MSCs could maintain these expressions and reverse PTX-related increases in BAX/BCL2 ratios. hUC-MSCs may be a promising agent with antioxidant and anti-apoptosis characteristics that can maintain sperm quality following chemotherapy treatment.

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.

Cell-Based Therapy Approaches in Treatment of Non-obstructive Azoospermia

The rate of infertility has globally increased in recent years for a variety of reasons. One of the main causes of infertility in men is azoospermia that is defined by the absence of sperm in the ejaculate and classified into two categories: obstructive azoospermia and non-obstructive azoospermia. In non-obstructive azoospermia, genital ducts are not obstructed, but the testicles do not produce sperm at all, due to various reasons. Non-obstructive azoospermia in most cases has no therapeutic options other than assisted reproductive techniques, which in most cases require sperm donors. Here we discuss cell-based therapy approaches to restore fertility in men with non-obstructive azoospermia including cell-based therapies of non-obstructive azoospermia using regenerative medicine and cell-based therapies of non-obstructive azoospermia by paracrine and anti-inflammatory pathway, technical and ethical challenges for using different cell sources and alternative options will be described, and then the more effectual approaches will be mentioned as future trends.

Mesenchymal stem cells promote spermatogonial stem/progenitor cell pool and spermatogenesis in neonatal mice in vitro

Prepubertal cancer treatment leads to irreversible infertility in half of the male patients. Current in vitro spermatogenesis protocols and cryopreservation techniques are inadequate to expand spermatogonial stem/progenitor cells (SSPC) from testicles. Bone marrow derived mesenchymal stem cells (BM-MSC) bearing a close resemblance to Sertoli cells, improved spermatogenesis in animal models. We asked if a co-culture setup supported by syngeneic BM-MSC that contributes to the air–liquid interphase (ALI) could lead to survival, expansion and differentiation of SSPCs in vitro. We generated an ALI platform able to provide a real-time cellular paracrine contribution consisting of syngeneic BM-MSCs to neonatal C57BL/6 mice testes. We aimed to evaluate the efficacy of this culture system on SSPC pool expansion and spermatogenesis throughout a complete spermatogenic cycle by measuring the number of total germ cells (GC), the undifferentiated and differentiating spermatogonia, the spermatocytes and the spermatids. Furthermore, we evaluated the testicular cell cycle phases, the tubular and luminal areas using histochemical, immunohistochemical and flow cytometric techniques. Cultures in present of BM-MSCs displayed survival of ID4(+) spermatogonial stem cells (SSC), expansion of SALL4(+) and OCT4(+) SSPCs, VASA(+) total GCs and Ki67(+) proliferative cells at 42 days and an increased number of SCP3(+) spermatocytes and Acrosin(+) spermatids at 28 days. BM-MSCs increased the percentage of mitotic cells within the G2-M phase of the total testicular cell cycle increased for 7 days, preserved the cell viability for 42 days and induced testicular maturation by enlargement of the tubular and luminal area for 42 days in comparison to the control. The percentage of PLZF(+) SSPCs increased within the first 28 days of culture, after which the pool started to get smaller while the number of spermatocytes and spermatids increased simultaneously. Our findings established the efficacy of syngeneic BM-MSCs on the survival and expansion of the SSPC pool and differentiation of spermatogonia to round spermatids during in vitro culture of prepubertal mice testes for 42 days. This method may be helpful in providing alternative cures for male fertility by supporting in vitro differentiated spermatids that can be used for round spermatid injection (ROSI) to female oocyte in animal models. These findings can be further exploited for personalized cellular therapy strategies to cure male infertility of prepubertal cancer survivors in clinics.

Secretions released from mesenchymal stem cells improve spermatogenesis restoration of cytotoxic treatment with busulfan in azoospermia mice

This study aimed at the efficacy of sequential treatment of bone marrow-derived mesenchymal stem cell secretion for busulfan-treated azoospermia in mice. The conditioned media (CM) was obtained from bone marrow mesenchymal stem cells (MSCs) or 293 cells. Chemically induced azoospermia mice received 200 μl MSC-CM or 293-CM twice a week intravenously for three consecutive weeks. The histological assessment of spermatogenic recovery quantifying the expression of meiosis-associated genes, and Sertoli cell barrier functional factors were assessed. The characteristics of TM4 cells (Sertoli cell line) after pre-incubation of MSC-CM in vitro were also obtained. The MSC-CM group had the most spermatogenic colonies among the three groups (p < .05), but no spermatids were seen. Expressions of the meiosis-associated genes Dazl, Vasa, Miwi, Stra8, CyclinA1, Pgk2 and Scp3 in MSC-CM testis were remarkably higher compared with 293-CM and busulfan groups respectively (p < .05). The levels of Sertoli cell barrier functional factors, for example ICAM-1 and N-cadherin, were significantly increased during MSC-CM treatment (p < .05). Moreover, pre-incubation of MSC-CM particularly accelerated the CD54 (ICAM-1) and CD44 expressions of TM4 cells and promoted cell inherent adhesion. MSC-CM treatment can significantly improve the short-term restoration of spermatogonial structures of chemically induced azoospermia related to facilitating Sertoli cell adhesion integrity.

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 umbilical cord perivascular cells prevent chemotherapeutic drug-induced male infertility in a mouse model

OBJECTIVE

To study whether intratesticular (IT) administration of 2 sources of human umbilical cord perivascular cells (HUCPVC), rich and potent sources of mesenchymal stromal cells (MSC), before chemotherapy can prevent infertility in a mouse model.

DESIGN

Two control groups of CD1 male mice without busulfan (BUS) administration (untreated and IT media injection groups) were included. Experimental groups included IT administration of media, first trimester (FTM) HUCPVCs or term HUCPVCs (n = 5 each) injected 3 days before BUS treatment (20 mg/kg). All groups were included in a mating time course study over 6 months.

SETTING

Preclinical study in a fertility center research laboratory.

PATIENTS

Not applicable.

INTERVENTION

IT delivery of FTM or term HUCPVC before BUS treatment.

MAIN OUTCOME MEASURES

Pregnancies, litter sizes, and gross morphology of offspring were monitored. Caudal epididymal sperm concentration, motility, and progressive motility were assessed by computer-assisted sperm analysis. Spermatogenesis was also assessed histologically in testicular tissue sections.

RESULTS

FTM and term HUCPVC displayed an MSC-associated immunophenotype and expressed transcripts encoding paracrine factors known to regulate the testicular cell niche. IT administration of FTM and term HUCPVC before chemotherapy promoted the recovery of spermatogenesis and fertility compared with BUS-treated animals that received a media injection. Although the total number of pups sired over 6 months by males treated with FTM or term HUCPVC was reduced compared with untreated or media-injected controls, litter size and sperm parameters in fertile animals did not differ between control and cell-treated groups.

CONCLUSION

HUCPVC represent a promising source of MSC-based therapy to prevent gonadotoxic chemotherapeutic drug-induced infertility.

Evaluating differentiation potential of the human menstrual blood-derived stem cells from infertile women into oocyte-like cells

One of the most intricate infertility problems among women is the number and quality of the oocytes. Menstrual blood-derived stem cells (MenSCs) are a recently discovered source of mesenchymal stem cells which is known as a suitable source of cells for regenerative medicine. We aimed to investigate whether MenSCs as autologous cell source from endometriosis, PCOS, and healthy women have different characteristics regarding their morphology, CD marker expression pattern, differentiation potential into oocyte-like cells, and oocyte-related genes expression. Menstrual blood samples (1-2 ml) from healthy and infertile women (PCOS and endometriosis) in the age range of 22-35 years were collected. Isolated MenSCs by the Ficoll-Paque density-gradient centrifugation method was characterized by flow cytometry. MenSCs were induced under 20 % follicular fluid (FF), and then they were evaluated for differentiation by Real time-PCR and immunocytochemistry assay. MenSCs derived from endometriosis women had different morphology from PCOS and healthy women, but similar regarding their CD marker pattern. All induced MenSCs showed morphological changes and expressed oocyte related genes (STELLA, GDF9, STRA8, PRDM, LHR, FSHR, SCP3, DDX4, and ZP2) in the 2nd week of culture, but there was a significant difference between the groups. Endometriosis-derived MenSCs showed higher levels of both gene and protein expressions. These findings propose that MenSCs derived from endometriosis and PCOS patients under 20 % FF, not only could differentiate into oocyte-like cells, but also showed more differential potential in comparison with healthy women. This indicates the possibility of using the patients' own MenSCs to differentiate into the oocyte-like cells.

Human umbilical cord perivascular cells maintain regenerative traits following exposure to cyclophosphamide

Chemotherapies can cause germ cell depletion and gonadal failure. When injected post-chemotherapy, mesenchymal stromal cells (MSCs) from various sources have been shown to have regenerative effects in rodent models of chemotherapy-induced gonadal injury. Here, we evaluated two properties of a novel source of MSC, first trimester (FTM) human umbilical cord perivascular cells (HUCPVCs) (with increased regenerative potential compared to older sources), that may render them a promising candidate for chemotherapeutic gonadal injury prevention. Firstly, their ability to resist the cytotoxic effects of cyclophosphamide (CTX) in vitro, as compared to term HUCPVCs and bone marrow cells (BMSCs); and secondly, whether they prevent gonadal dysfunction if delivered prior to gonadotoxic therapy in vivo. BMSC, FTM HUCPVC, term HUCPVC, and control NTERA2 cells were treated with moderate (150 μmol/L) and high (300 μmol/L) doses of CTX in vitro. Viability, proliferative capacity, mesenchymal cell lineage markers and differentiation capacity, immunogenicity, and paracrine gene expression were assessed. CTX was administered to Wistar rats 2 days following an intra-ovarian injection of FTM HUCPVC. HUCPVC survival and ovarian follicle numbers were assessed using histological methods. We conclude that FTM HUCPVC maintain key regenerative properties following chemotherapy exposure and that pre-treatment with these cells may prevent CTX-induced ovarian damage in vivo. Therefore, HUCPVCs are promising candidates for fertility preservation.

Hypoxia-Preconditioned Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells Mitigate Hypoglycemic Testicular Injury Induced by Insulin in Rats

Hypoglycemia is a neglected metabolic disorder. Thus, we evaluated the protective effect of hypoxia-preconditioned human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) on hypoglycemic testicular injury. We examined 56 testes from 28 animals: 7 rats with insulin-induced hypoglycemia (HG group), 7 hypoglycemic rats which received an intratesticular injection of hUCB-MSCs (HG-MSC group), and 14 untreated control rats. Testosterone level, testicular catalase (CAT) activity, and malondialdehyde (MDA) level were analyzed. Immunostaining for specific testicular germ and somatic cell markers was performed. Proliferating and apoptotic cells were detected by anti-PCNA and anti-caspase-3, respectively. Morphometrical data were statistically analyzed. The hypoglycemic rats showed a significant decrease in testosterone level and CAT activity and a significant increase in MDA production. Examination of histological structure and protein expression of diverse germ cell markers revealed collapsed tubules that were lined by degenerated germ cells, decreased lactate dehydrogenase type C immune expression, as well as decreased proliferating and increased apoptotic cells number in hypoglycemic testes. Injection of MSCs improved testicular biochemical parameters, preserved germ cells and somatic cells, and decreased apoptosis. In conclusion, hypoxia-preconditioned hUCB-MSCs attenuate rat testicular injury caused by insulin-induced hypoglycemia. Avoidance and rapid management of hypoglycemia are necessary to avoid significant testicular injury.

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.

Restoration of functional sperm production in irradiated pubertal rhesus monkeys by spermatogonial stem cell transplantation

BACKGROUND

In male pre-pubertal cancer patients, radiation and chemotherapy impact future fertility by eradication of spermatogonial stem cells (SSCs). In macaques, spermatogenesis could be regenerated by intratesticular transplantation of SSCs, but only a small percentage of spermatozoa produced were of donor origin. Transient hormone suppression with a GnRH antagonist (GnRH-ant) enhanced spermatogenic recovery from transplanted SSCs.

OBJECTIVES

To evaluate donor-derived and endogenous spermatogenic recovery after SSC transplantation into irradiated monkeys and to test whether hormone suppression around the time of transplantation facilitates spermatogenic recovery.

MATERIALS AND METHODS

Testes of 15 adult rhesus monkeys were irradiated with 7 Gy and 4 months later transplanted, to one of the testes, with cryopreserved testicular cells containing SSCs from unrelated monkeys. Monkeys were either treated with GnRH-ant for 8 weeks before transplantation, GnRH-ant from 4 weeks before to 4 weeks after transplantation, or with no GnRH-ant. Tissues were harvested 10 months after transplantation.

RESULTS

Two of the 15 monkeys, a control and a pre-transplantation GnRH-ant-treated, showed substantially higher levels of testicular spermatogenesis and epididymal sperm output in the transplanted side as compared to the untransplanted. Over 84% of epididymal spermatozoa on the transplanted side had the donor genotype and were capable of fertilizing eggs after intracytoplasmic sperm injection forming morulae of the donor paternal origin. Low levels of donor spermatozoa (~1%) were also identified in the epididymis of three additional monkeys. Transplantation also appeared to enhance endogenous spermatogenesis.

DISCUSSION AND CONCLUSION

We confirmed that SSC transplantation can be used for restoration of fertility in male cancer survivors exposed to irradiation as a therapeutic agent. The success rate of this procedure, however, is low. The success of filling the tubules with the cell suspension, but not the GnRH-ant treatment, was related to the level of colonization by transplanted cells.

Inhibiting Necroptosis of Spermatogonial Stem Cell as a Novel Strategy for Male Fertility Preservation

Fertility preservation is a common concern for male cancer survivors of reproductive age. However, except for testicular tissue cryopreservation, which is not very effective, there is no feasible and precise therapy capable of protecting spermatogenesis for prepubertal boys before or during gonadotoxic treatment. This study aims to investigate the effects of inhibiting necroptosis of spermatogonial stem cell (SSC) in fertility preservation. Male mice 12 weeks of age were used to establish gonadotoxicity with two intraperitoneal injections of busulfan at a total dose of 40 mg kg^-1. The mouse model and the primary cultured mouse SSCs were used to characterize the relationship between necroptosis of SSC and gonadotoxicity. Meanwhile, the effects of an inhibitor of necroptosis pathway, RIPA-56, were observed on day 36 in the mouse model of busulfan-induced gonadotoxicity. We found that the number of SSCs was decreased, but the level of necroptosis was upregulated on day 18 after busulfan treatment in testes from gonadotoxic mice. Further experiments in primary cultured cells showed that the necroptosis caused cell death in busulfan-treated SSCs and could be inhibited by RIPA-56. After suppressing the necroptosis of SSCs, the busulfan-induced mice had a decreased loss of spermatogenic cells as shown by histology and an increased Johnsen's score. Moreover, the quantities of SSCs and epididymal spermatozoa were restored after intervention with RIPA-56, indicating a series of beneficial effects by targeting the necroptosis of SSCs in mice undergoing busulfan treatment. In conclusion, our findings reveal that the necroptosis of SSCs plays a critical role in busulfan-induced gonadotoxicity and may be a potential target for male fertility preservation.

Altered expression of some miRNAs and their target genes following mesenchymal stem cell treatment in busulfan-induced azoospermic rats

Studies have recently demonstrated that mesenchymal stem cells (MSCs) have therapeutic capabilities on many diseases and this effect is mainly mediated by miRNAs. However, the actual mechanism of MSCs paracrine effect on testis to improve male fertility is still elusive. Herein, we evaluated the altered expression of some spermatogenesis-related miRNAs and their target genes following transplantation of bone marrow (BM)-derived MSCs into testes of busulfan-induced azoospermic rats using real time PCR. Transplantation of MSCs improved fertility of azoospermic rats as revealed by enhanced serum levels of testosterone and estradiol, and upregulated expression of germ cell‑specific genes. Azo rats injected with MSCs also exhibited a significant downregulated expression of miRNA-19b, miRNA-100, miRNA-141, miRNA‑146a, miRNA-429, and let‑7a and a significant upregulated expression of miRNA-21, miRNA-34b, miRNA-34c, miRNA-122, miRNA-449a, miRNA-449b, and miRNA-449c in the testis as compared to Azo rats injected with phosphate buffer saline. Transplantation of MSCs was also accompanied with restoration of the disrupted expression of Ccnd1, E2F1, Myc, and PLCXD3 (target genes for miRNA-34 and miRNA‑449 clusters) and ERα and AKT1 (target genes for miRNA-100 and let‑7a) to level comparable to that of the fertile group. Upon these data, we infer that BM-MSCs can improve fertility of azoospermic rats and this effect was followed by altered expression of some spermatogenesis-related miRNAs and their target genes. These findings provide MSCs as a promising and effective cell-based therapeutic method for azoospermic patients, but further investigations are required before clinical application.

Urine-Derived Stem Cells Facilitate Endogenous Spermatogenesis Restoration of Busulfan-Induced Nonobstructive Azoospermic Mice by Paracrine Exosomes

Nonobstructive azoospermia (NOA) is a severe form of male infertility, with limited effective treatments. Urine-derived stem cells (USCs) possess multipotent differentiation capacity and paracrine effects, and participate in tissue repair and regeneration. The aim of this study is to investigate whether the transplantation of USCs or USC exosomes (USC-exos) could promote endogenous spermatogenesis restoration in a busulfan-induced NOA mice model. USCs were cultured and characterized by flow cytometry. High-density USCs were cultured in a hollow fiber bioreactor for exosomes collection. USC-exos were isolated from USCs conditional media and identified by transmission electron microscopy, western blotting, and Flow NanoAnalyzer analysis. USC-exos exhibited sphere- or cup-shaped morphology with a mean diameter of 66.5 ± 16.0 nm, and expressed CD63 and CD9. USCs and USC-exos were transplanted into the interstitial space in the testes of NOA mice per the following groups: normal group; groups treated with no injection, phosphate-buffered saline (PBS), USCs or USC-exos on days 3 and 36 after busulfan administration, respectively. Thirty days after USCs and USC-exos transplantation, spermatogenesis was restored by both USCs and USC-exos in NOA mice 36 days after busulfan treatment as confirmed by immunofluorescence staining and hematoxylin and eosin staining. Moreover, spermatogenic genes (Pou5f1, Prm1, SYCP3, and DAZL) and the spermatogenic protein UCHL1 were significantly increased in both the USCs 36 and USC-exos36 groups compared with the PBS group, as demonstrated using quantitative real-time polymerase chain reaction and western blot analysis. However, the transplantation of USCs or USC-exos at day 3 after busulfan treatment did not improve spermatogenesis in NOA mice. Our study demonstrated that USCs could facilitate endogenous spermatogenesis restoration of busulfan-induced NOA mice through paracrine exosomes but could not protect the mouse testicles at the early stage of destruction caused by busulfan. This study provides a novel insight into the treatment of NOA.

Role of stem cells in fertility preservation: current insights

While improvements made in the field of cancer therapy allow high survival rates, gonadotoxicity of chemo- and radiotherapy can lead to infertility in male and female pre- and postpubertal patients. Clinical options to preserve fertility before starting gonadotoxic therapies by cryopreserving sperm or oocytes for future use with assisted reproductive technology (ART) are now applied worldwide. Cryopreservation of pre- and postpubertal ovarian tissue containing primordial follicles, though still considered experimental, has already led to the birth of healthy babies after autotransplantation and is performed in an increasing number of centers. For prepubertal boys who do not produce gametes ready for fertilization, cryopreservation of immature testicular tissue (ITT) containing spermatogonial stem cells may be proposed as an experimental strategy with the aim of restoring fertility. Based on achievements in nonhuman primates, autotransplantation of ITT or testicular cell suspensions appears promising to restore fertility of young cancer survivors. So far, whether in two- or three-dimensional culture systems, in vitro maturation of immature male and female gonadal cells or tissue has not demonstrated a capacity to produce safe gametes for ART. Recently, primordial germ cells have been generated from embryonic and induced pluripotent stem cells, but further investigations regarding efficiency and safety are needed. Transplantation of mesenchymal stem cells to improve the vascularization of gonadal tissue grafts, increase the colonization of transplanted cells, and restore the damaged somatic compartment could overcome the current limitations encountered with transplantation.

Mesenchymal stem cell-secreted factors delayed spermatogenesis injuries induced by busulfan involving intercellular adhesion molecule regulation

The present study was designed to investigate the therapeutic effect of bone marrow MSC-derived factors on gonadotropic toxicity induced by busulfan in vivo. The conditioned media (CM) was obtained from MSCs in serum-free incubation for 48 hr and concentrated ~25-fold by ultrafiltration. The CM of HEK 293 cells was treated as control (293-CM). MSC-CM was injected into busulfan mice via caudal veins after 1 day of busulfan treatment for 2 weeks (200 μl per dose/twice weekly）. Compared to the 293-CM group, testicular injury was delayed in MSC-CM group, including reduced vacuolations of cells in the basal compartment of the seminiferous epithelium and detachment of cells from basement membrane. Apoptotic spermatogenic cells were significantly decreased in MSC-CM group (p ＜ 0.05). Interesting N-cadherin，ICAM-1 and P-cadherin expressions significantly increased in MSC-CM group, while occludin, ZO-1 and connexin 43 expressions showed no difference among MSC-CM, 293-CM and busulfan groups. Present results suggest MSC-secreted factors protect spermatogenesis impairment after busulfan treatment by reducing the apoptosis of spermatogenic cells and enhancing intercellular adhesion molecule expressions.

Efficient generation of male germ-like cells derived during co-culturing of adipose-derived mesenchymal stem cells with Sertoli cells under retinoic acid and testosterone induction

BACKGROUND

Adipose-derived mesenchymal stem cells (ADMSCs) are considered an efficient and important candidate for male infertility treatment because they contain pluripotent stem cells, which can differentiate into all cells from three germ layers. However, the efficient generation of male germ-like cell (MGLCs) is one of the key issues, and little is known about the mechanisms underlying generation of MGLCs. Herein, we attempt to improve the efficient generation of MGLCs derived during co-culturing of rat ADMSCs with SCs under retinoic acid (RA) and testosterone (T) treatment.

METHODS

ADMSCs isolated from male SD rat were induced into generation of MGLCs by using respective methods in vitro. Transwell insert system was used for co-culturing. Busulfan-induced non-obstructive azoospermia rat mode was used to evaluate spermatogenic recovery ability of treated ADMSCs. Besides, the relative gene expression level was detected by reverse transcription PCR, quantitative RT-PCR. The relative protein expression level was detected by western blot (WB) and immunostaining analysis.

RESULTS

The results showed that ADMSCs co-cultured with TM4 cells under RA and T induction enhanced the formation of bigger and tightly packed MGLCs feature colonies in vitro. Moreover, the expression of male germ cell-related markers (Oct4, Stella, Ddx4, Dazl, PGP9.5, Stra8, and ITGα6) is significantly upregulated in TM4 cell-co-cultured ADMSCs in vitro and in busulfan-treated rat testis after injecting TM4 cell-treated ADMSCs for 2 months. Comparatively, the ADMSCs treated by TM4 cell with RA and T exhibited the highest expression of male germ cell-related markers. RA- and T-treated TM4 cell showed fewer dead cells and higher cytokine secretion than untreated groups. The protein expression level of TGFβ-SMAD2/3, JAK2-STAT3, and AKT pathways in ADMSCs co-cultured with TM4 cells under RA and T was higher than others. Whereas, downregulation of male germ cell-related marker expression subsequently inhibited the phosphorylation of SMAD2/3, JAK2, STAT3, and AKT.

CONCLUSION

These results suggested that TM4 cells could efficiently stimulate in vitro generation of MGLCs during co-culturing of ADMSCs under RA and T treatment. Conclusively, the ADMSCs co-cultured with TM4 cell under RA and T induction stimulate the efficient generation of MGLCs in vitro through activating TGFβ-SMAD2/3, JAK2-STAT3, and AKT pathways. Among them, JAK2-STAT3 and AKT pathways are being first reported to show involvement of in vitro generation of MGLCs during ADMSC co-culturing with SCs.

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.

Can mesenchymal stem cells improve spermatogonial stem cell transplantation efficiency?

Improved treatments have led to an increased survival rate in cancer patients. However, in pre-pubertal boys, these gonadotoxic treatments can result in the depletion of the spermatogonial stem cell (SSC) pool causing lifelong infertility. SSC transplantation has been proposed as a promising technique to preserve the fertility of these patients. In mice, this technique has resulted in live-born offspring, but the efficiency of colonization remained low. This could be because of a deficient microenvironment, leading to apoptosis of the transplanted SSCs. Interestingly, mesenchymal stem cells (MSCs), being multipotent and easy to isolate and multiply in vitro, are nowadays successfully and widely used in regenerative medicine. Here, we shortly review the current understanding of MSC and SSC biology, and we hypothesize that a combined MSC-SSC transplantation might improve the efficiency of SSC colonization and differentiation as paracrine factors from MSCs may contribute to the SSC niche.

Making gametes from alternate sources of stem cells: past, present and future

Infertile couples including cancer survivors stand to benefit from gametes differentiated from embryonic or induced pluripotent stem (ES/iPS) cells. It remains challenging to convert human ES/iPS cells into primordial germ-like cells (PGCLCs) en route to obtaining gametes. Considerable success was achieved in 2016 to obtain fertile offspring starting with mouse ES/iPS cells, however the specification of human ES/iPS cells into PGCLCs in vitro is still not achieved. Human ES cells will not yield patient-specific gametes unless and until hES cells are derived by somatic cell nuclear transfer (therapeutic cloning) whereas iPS cells retain the residual epigenetic memory of the somatic cells from which they are derived and also harbor genomic and mitochondrial DNA mutations. Thus, they may not be ideal starting material to produce autologus gametes, especially for aged couples. Pluripotent, very small embryonic-like stem cells (VSELs) have been reported in adult tissues including gonads, are relatively quiescent in nature, survive oncotherapy and can be detected in aged, non-functional gonads. Being developmentally equivalent to PGCs (natural precursors to gametes), VSELs spontaneously differentiate into gametes in vitro. It is also being understood that gonadal stem cells niche is compromised by oncotherapy and with age. Improving the gonadal somatic niche could regenerate non-functional gonads from endogenous VSELs to restore fertility. Niche cells (Sertoli/mesenchymal cells) can be directly transplanted and restore gonadal function by providing paracrine support to endogenous VSELs. This strategy has been successful in several mice studies already and resulted in live birth in a woman with pre-mature ovarian failure.

Molecular effect of human umbilical cord blood CD34-positive and CD34-negative stem cells and their conjugate in azoospermic mice

Currently, azoospermia is one of the most common diseases of male infertility. Stem cell research is the new hope for novel therapy with a higher degree of safety and lower cost. This study aimed to investigate the effect of umbilical cord blood-derived stem cells (" and mesenchymal "UCB-MSCs") and mono-cell layer implanted into the induced azoospermic mice testis. Stem cells were isolated from umbilical cord blood and CD34+ve cells were separated from negative one by Mini MACs column. At 5th week after single injection of busulfan, stained mesenchymal (CD34-ve), hematopoietic stem cells (CD34+ve) and their conjugate (mono-cell layer) were injected locally into testis. At the end of the study, MSCs group showed that mRNA levels of genes related to meiosis (Vasa, SCP3, and PgK2) were increased with significant decrease of FSH and LH levels, compared to control group. Histologically, most of the tubules restored normal architecture. In contrast, HSCs and mono-cell layer groups showed statically insignificant change of FSH, LH, and gene expression, compared to control group. Histologically, distorted seminiferous tubules, with reduction in sperm content, and interstitial mononuclear cellular infiltration were seen. There was significant increase in the optical density of PCNA immune reaction in MSCs group than azoospermia, HSCs, and mono-cell layer, while there was non-significant difference between MSCs and control group. The present study suggested that injection of MSCs into chemotherapeutic-induced azoospermia in mice improved testicular failure; histologically and functionally, by restoration of spermatogenic gene expression while HSC and mono-cell layer showed no effect on spermatogenesis added to that mono-cell layer may induce testicular tissue damage.

Human umbilical perivascular cells: a novel source of MSCs to support testicular niche regeneration

The expansion of functional testicular biopsy-derived human spermatogonial stem cells (hSSC) ex-vivo may enable the restoration of fertility in pre-pubertal males having undergone gonadotoxic therapies or men with severe male factor infertility. Various somatic cells are known to regulate SSC homeostasis and spermatogenesis in the developing and adult testis. Prior attempts to recapitulate this niche demonstrated the requirement of feeder cells, such as endogenous testicular somatic cells, for germ cell expansion ex-vivo. However, this strategy has limitations for the expansion of hSSCs from tissue biopsies where spermatogenesis is absent or defective. Our aim was to evaluate first trimester human umbilical cord perivascular cells (FTM HUCPVCs), a novel source of mesenchymal stromal-like cells (MSCs), as potential human feeder cells for standardized hSSC expansion ex-vivo. Targeted RNA sequencing analysis demonstrated that CD90+ve FTM HUCPVCs expanded in vitro under germ cell culture conditions express a profile of targeted testicular-associated transcripts that is similar to cultured human CD90+ve testicular adherent cells (hTACs) and secrete LIF, FGF2 and BMP4, key growth factors known to regulate spermatogenesis. We also demonstrated that mitotically-inactivated FTM HUCPVCs support the expansion of mouse germ cells and putative SSCs ex-vivo, and that FTM HUCPVC transplantation promotes in vivo germ cell regeneration following mono-2- ethylhexyl phthalate (MEHP)-induced seminiferous tubule damage in a murine model, including a partial reconstitution of tubular cellular architecture and reestablishment of DAZL and acrosin+ve germ cell layers. Together, these data suggest that FTM HUCPVCs have phenotypical and functional properties that may support repair of the human testicular niche.

Making gametes from pluripotent stem cells--a promising role for very small embryonic-like stem cells

The urge to have one's own biological child supersedes any desire in life. Several options have been used to obtain gametes including pluripotent stem cells (embryonic ES and induced pluripotent iPS stem cells); gonadal stem cells (spermatogonial SSCs, ovarian OSCs stem cells), bone marrow, mesenchymal cells and fetal skin. However, the field poses a huge challenge including inefficient existing protocols for differentiation, epigenetic and genetic changes associated with extensive in vitro manipulation and also ethical/regulatory constraints. A tremendous leap in the field occurred using mouse ES and iPS cells wherein they were first differentiated into epiblast-like cells and then primordial germ cell-like cells. These on further development produced sperm, oocytes and live offspring (had associated genetic problems). Evidently differentiating pluripotent stem cells into primordial germ cells (PGCs) remains a major bottleneck. Against this backdrop, we propose that a novel population of pluripotent stem cells termed very small embryonic-like stem cells (VSELs) may serve as an alternative, potential source of autologus gametes, keeping in mind that they are indeed PGCs surviving in adult mammalian ovaries and testes. Both VSELs and PGCs are pluripotent, relatively quiescent because of epigenetic modifications of parentally imprinted genes loci like Igf2-H19 and KCNQ1p57, share several markers like Stella, Fragilis, Mvh, Dppa2, Dppa4, Sall4, Blimp1 and functional receptors. VSELs are localized in the basement membrane of seminiferous tubules in testis and in the ovary surface epithelium. Ovarian stem cells from mouse, rabbit, sheep, marmoset and humans (menopausal women and those with premature ovarian failure) spontaneously differentiate into oocyte-like structures in vitro with no additional requirement of growth factors. Thus a more pragmatic option to obtain autologus gametes may be the pluripotent VSELs and if we could manipulate them in vivo - existing ethical and epigenetic/genetic concerns associated with in vitro culture may also be minimized. The field of oncofertility may undergo a sea-change and existing strategies of cryopreservation of gametes and gonadal tissue for fertility preservation in cancer patients will necessitate a revision. However, first the scientific community needs to arrive at a consensus about VSELs in the gonads and then work towards exploiting their potential.