Oocyte generation in adult mammalian ovaries by putative germ cells in bone marrow and peripheral blood

Which Side of the Coin Are You on Regarding Possible Postnatal Oogenesis?

It is well known that oocytes are produced during fetal development and that the total number of primary follicles is determined at birth. In humans, there is a constant loss of follicles after birth until about two years of age. The number of follicles is preserved until the resumption of meiosis at puberty and there is no renewal of the oocytes; this dogma was maintained in the last century because there were no suitable techniques to detect and obtain stem cells. However, following stem cell markers, several scientists have detected them in developing and adult human ovarian tissues, especially in the ovarian surface epithelial cells. Furthermore, many authors using different methodological strategies have indicated this possibility. This evidence has led many scientists to explore this hypothesis; there is no definitive consensus to accept this idea. Interestingly, oocyte retrieval from mature ovaries and other tissue sources of stem cells has contributed to the development of strategies for the retrieval of mature oocytes, useful for assisted reproductive technology. Here, we review the evidence and controversies on oocyte neooogenesis in adult women; in addition, we agree with the idea that this process may occur in adulthood and that its alteration may be related to various pathologies in women, such as polycystic ovary syndrome, premature ovarian insufficiency, diminished ovarian reserve and several infertility and genetic disorders.

Exploring stem cell technology: Pioneering new pathways for female fertility preservation and restoration

The fertility of women is crucial for the well-being of individuals and families. However, various factors such as chemotherapy, lifestyle changes, among others, may lead to a decline in female fertility, thus emphasizing the significance of preserving and restoring fertility. Stem cells, with their unique capacity for self-renewal and pluripotent differentiation, have made significant strides in areas such as ovarian tissue cryopreservation, in vitro culture of frozen-thawed ovarian tissue, and construction of ovarian-like organs. This review aims to summarize the latest findings in these fields, highlighting the pivotal role, mechanisms, and future prospects of stem cell technology in preserving and restoring female fertility. Additionally, the importance of interdisciplinary collaboration is underscored, as personalized stem cell therapy regimens tailored through interdisciplinary cooperation between reproductive medicine and stem cell fields hold promise in providing reliable solutions for the preservation and restoration of female fertility.

Deoxynivalenol induces ovarian damage and uterine changes in prepubertal and adult mice

Deoxynivalenol (DON) is associated with reproductive toxicity in animals. The frequent contamination of cereal-based foods with DON and the high intake of these by children raises particular concern about the susceptibility of this subpopulation to adverse effects from this mycotoxin. However, age-related differences in the in vivo reproductive toxicity of DON have not been evaluated. Therefore, the effects of DON on serum follicle-stimulating hormone (FSH) levels, histology, and inflammatory and oxidative stress responses in the ovaries and uteruses of prepubertal and adult mice were investigated. Twenty female prepubertal Swiss mice (21 days old) and 20 young adult mice (65 days old) were fed a control diet or a diet containing 10 mg of DON/kg of feed for 15 days (prepubertal mice) and 28 days (adult mice). In the ovaries, DON induced an increase in the lesional score in both age groups. Ingestion of DON decreased FSH levels in prepubertal females, whereas an increase was observed in adult mice. In prepubertal mice, a reduction in the number of macrophages and increased levels of TNF-α were observed in the ovaries of the DON group, while in adult animals, an increase in the number of macrophages and higher levels of TNF-α were noted. Exposure to DON led to an increase in type I collagen in the uteruses of adult mice, while in prepubertal mice, a decrease in type III collagen was observed. DON exposure also resulted in a decrease in FRAP levels and an increase in ABTS and lipid peroxidation in the uteruses of prepubertal mice. Taken together, the results indicate that the effects of DON on reproductive organs are age-specific, with toxicity established as early as the prepubertal period.

Ovarian microenvironment: challenges and opportunities in protecting against chemotherapy-associated ovarian damage

BACKGROUND

Chemotherapy-associated ovarian damage (CAOD) is one of the most feared short- and long-term side effects of anticancer treatment in premenopausal women. Accumulating detailed data show that different chemotherapy regimens can lead to disturbance of ovarian hormone levels, reduced or lost fertility, and an increased risk of early menopause. Previous studies have often focused on the direct effects of chemotherapeutic drugs on ovarian follicles, such as direct DNA damage-mediated apoptotic death and primordial follicle burnout. Emerging evidence has revealed an imbalance in the ovarian microenvironment during chemotherapy. The ovarian microenvironment provides nutritional support and transportation of signals that stimulate the growth and development of follicles, ovulation, and corpus luteum formation. The close interaction between the ovarian microenvironment and follicles can determine ovarian function. Therefore, designing novel and precise strategies to manipulate the ovarian microenvironment may be a new strategy to protect ovarian function during chemotherapy.

OBJECTIVE AND RATIONALE

This review details the changes that occur in the ovarian microenvironment during chemotherapy and emphasizes the importance of developing new therapeutics that protect ovarian function by targeting the ovarian microenvironment during chemotherapy.

SEARCH METHODS

A comprehensive review of the literature was performed by searching PubMed up to April 2024. Search terms included 'ovarian microenvironment' (ovarian extracellular matrix, ovarian stromal cells, ovarian interstitial, ovarian blood vessels, ovarian lymphatic vessels, ovarian macrophages, ovarian lymphocytes, ovarian immune cytokines, ovarian oxidative stress, ovarian reactive oxygen species, ovarian senescence cells, ovarian senescence-associated secretory phenotypes, ovarian oogonial stem cells, ovarian stem cells), terms related to ovarian function (reproductive health, fertility, infertility, fecundity, ovarian reserve, ovarian function, menopause, decreased ovarian reserve, premature ovarian insufficiency/failure), and terms related to chemotherapy (cyclophosphamide, lfosfamide, chlormethine, chlorambucil, busulfan, melphalan, procarbazine, cisplatin, doxorubicin, carboplatin, taxane, paclitaxel, docetaxel, 5-fluorouraci, vincristine, methotrexate, dactinomycin, bleomycin, mercaptopurine).

OUTCOMES

The ovarian microenvironment shows great changes during chemotherapy, inducing extracellular matrix deposition and stromal fibrosis, angiogenesis disorders, immune microenvironment disturbance, oxidative stress imbalances, ovarian stem cell exhaustion, and cell senescence, thereby lowering the quantity and quality of ovarian follicles. Several methods targeting the ovarian microenvironment have been adopted to prevent and treat CAOD, such as stem cell therapy and the use of free radical scavengers, senolytherapies, immunomodulators, and proangiogenic factors.

WIDER IMPLICATIONS

Ovarian function is determined by its 'seeds' (follicles) and 'soil' (ovarian microenvironment). The ovarian microenvironment has been reported to play a vital role in CAOD and targeting the ovarian microenvironment may present potential therapeutic approaches for CAOD. However, the relation between the ovarian microenvironment, its regulatory networks, and CAOD needs to be further studied. A better understanding of these issues could be helpful in explaining the pathogenesis of CAOD and creating innovative strategies for counteracting the effects exerted on ovarian function. Our aim is that this narrative review of CAOD will stimulate more research in this important field.

REGISTRATION NUMBER

Not applicable.

Changes in Rehmanniae Radix processing and their impact on ovarian hypofunction: potential mechanisms of action

Objective

This study evaluates the research developments concerning Rehmanniae Radix in ovarian hypofunction diseases. It explores the processing methods of Rehmanniae Radix, the variations in its compounds before and after processing, the mechanism of Rehmanniae Radix and its active compounds in improving ovarian function, and the advancements in clinical applications of traditional Chinese medicine (TCM) compound that include Rehmanniae Radix.

Methods

Comprehensive literature search was conducted using databases such as China National Knowledge Infrastructure (CNKI), China Science and Technology Journal Database, National Science and Technology Library, the Pharmacopoeia of the People's Republic of China, Pubmed, and the Web of Science Database. The search utilized the following Medical Subject Headings (MeSH) and keywords: "Rehmanniae Radix," "Drying Rehmannia Root," "Rehmannia glutinosa," "Rehmanniae Radix Praeparata," "Traditional Chinese Medicine Processing," "Pharmacological Effects," "Ovarian Aging," "Diminished ovarian reserve," "Premature ovarian insufficiency," "Premature Ovarian Failure," "Ovarian hypofunction diseases".

Results

The ancient Chinese medical books document various processing techniques for Rehmanniae Radix. Contemporary research has identified changes in its compounds processing and the resultant diverse therapeutic effects. When processed into Rehmanniae Radix Praeparata, it is noted for its ability to invigorate the kidney. TCM compound containing Rehmanniae Radix is frequently used to treat ovarian hypofunction diseases, demonstrating significant clinical effectiveness. The key changes in its compounds processing include cyclic dilute ether terpene glycosides, phenylethanol glycosides, sugars, and 5-hydroxymethylfurfural. Its pharmacological action is primarily linked to the improvement of granulosa cell proliferation, antioxidative and anti-aging properties, and modulation of the immune and inflammatory microenvironment. Furthermore, Rehmanniae Radix also offers therapeutic benefits for cardiovascular and cerebrovascular diseases, osteoporosis and cognitive dysfunction caused by low estrogen levels. Thereby Rehmanniae Radix mitigates both the short-term and long-term health risks associated with ovarian hypofunction diseases.

Conclusion

Processed Rehmanniae Radix has shown potential to improve ovarian function, and its compound prescriptions have a definite effect on ovarian dysfunction diseases. Therefore Rehmanniae Radix was garnering interest for both basic and clinical research, with promising application prospects as a future therapeutic agent for ovarian hypofunction diseases. However, further studies on its toxicology and the design of standardized clinical trials are necessary to fully establish its efficacy and safety.

Leukocyte telomere length and DNA methylome as biomarkers of ovarian reserve and embryo aneuploidy: the intricate relationship between somatic and reproductive aging

The average childbearing age among women continues to rise, leading to an increased prevalence of infertility and a subsequent increased use of assisted reproductive technologies (ARTs). Ovarian aging, especially diminished ovarian reserve and poor ovarian response, have been implicated as common causes of infertility. Telomere length and DNA methylation-based epigenetic clocks are established hallmarks of cellular aging; however, the interplay between somatic and ovarian aging remains unclear. There appears to be a lack of correlation between leukocyte telomere length and the DNA methylation age of somatic and ovarian cells. Both the telomere length and methylome of follicular somatic cells (granulosa and cumulus) appear to be unaffected by chronologic age, infertility, or processes that result in diminished ovarian reserve and poor ovarian response. As such, they are unlikely candidates as surrogate biomarkers of reproductive potential, response to stimulation, or ART outcome. Meanwhile, telomere or methylome changes in leukocytes associated with aging seem to correlate with reproductive function and may have the potential to aid the characterization of women with reproductive decline; however, current data are limited and larger studies evaluating this within an ART setting are warranted.

In-vivo oogenesis of oogonial and mesenchymal stem cells seeded in transplanted ovarian extracellular matrix

OBJECTIVE (S)

One way to overcome the recurrence of cancer cells following ovarian tissue transplantation is to use decellularized tissues as a scaffold that does not have any cellular components. These cell-free scaffolds can be seeded with different type of stem cells for ovarian restoration.

MATERIALS AND METHODS

OSCs, PMSCs and BMSCs (oogonial, peritoneal and bone marrow mesenchymal stem cells, respectively) were seeded into human decellularized ovarian tissue as 4 groups: Scaffold + OSCs (SO), Scaffold + OSC + PMSCs (SOP), Scaffold + OSC + BMSCs (SOB) and Scaffold + OSC + PMSCs + BMSCs (SOPB). The produced grafts were transplanted into the sub-peritoneal space of ovariectomized NMRI mice as artificial ovary (AO). The expression of Vegf, CD34, Gdf9, Zp3, Ddx4, Amh and Lhr genes in AOs were measured by qRT-PCR. Also, histotechniques were considered to detect the anti GFP, PCNA, VEGF, GDF9, ZP3 and AMH proteins.

RESULTS

H & E staining showed follicle-like structures in all groups; the number of these structures, in the SOP and SOB groups, were the highest. In SO group, differentiation ability to oocyte and granulosa cells was observed. Endothelial, oocyte, germ, and granulosa cell-like cells were specially seen in SOP and angiogenesis capability was more in SOB group. However, angiogenesis ability and differentiation to theca cell-like cells were more often in SOPB group. While none of the groups showed a significant difference in AMH level, estradiol levels were significantly higher in SOPB group.

CONCLUSION

Integration of OSCs + PMSCs and those OSCs + BMSCs were more conducive to oogenesis.

Mitochondrial Transfer into Human Oocytes Improved Embryo Quality and Clinical Outcomes in Recurrent Pregnancy Failure Cases

One of the most critical issues to be solved in reproductive medicine is the treatment of patients with multiple failures of assisted reproductive treatment caused by low-quality embryos. This study investigated whether mitochondrial transfer to human oocytes improves embryo quality and provides subsequent acceptable clinical results and normality to children born due to the use of this technology. We transferred autologous mitochondria extracted from oogonia stem cells to mature oocytes with sperm at the time of intracytoplasmic sperm injection in 52 patients with recurrent failures (average 5.3 times). We assessed embryo quality using the following three methods: good-quality embryo rates, transferable embryo rates, and a novel embryo-scoring system (embryo quality score; EQS) in 33 patients who meet the preset inclusion criteria for analysis. We also evaluated the clinical outcomes of the in vitro fertilization and development of children born using this technology and compared the mtDNA sequences of the children and their mothers. The good-quality embryo rates, transferable embryo rates, and EQS significantly increased after mitochondrial transfer and resulted in 13 babies born in normal conditions. The mtDNA sequences were almost identical to the respective maternal sequences at the 83 major sites examined. Mitochondrial transfer into human oocytes is an effective clinical option to enhance embryo quality in recurrent in vitro fertilization-failure cases.

Translocations are induced in hematopoietic stem cells after irradiation of fetal mice

Although mammalian fetuses have been suggested to be sensitive to radiation, an increased frequency of translocations was not observed in blood lymphocytes from atomic bomb (A-bomb) survivors who were exposed to the bomb in utero and examined as adults. Since experiments using hematopoietic cells of mice and rats confirmed this finding, it was hypothesized that either irradiated fetal hematopoietic stem cells (f-HSCs) cannot generate exchange-type chromosomal aberrations or cells bearing induced aberrations are eliminated before the animals reach adulthood. In the present study, pregnant mice (12.5-15.5 days post coitum [dpc]) were irradiated with 2 Gy of X-rays and long-term HSCs (LT-HSCs) were isolated 24 h later. Multicolor fluorescence in situ hybridization (mFISH) analysis of LT-HSC clones proliferated in vitro showed that nine out of 43 (21%) clones from fetuses and 21 out of 41 (51%) clones from mothers bore translocations. These results indicate that cells with translocations can arise in mouse f-HSCs but exist at a lower frequency than in the mothers 24 h after X-ray exposure. Thus, it seems likely that translocation-bearing f-HSCs are generated but subsequently disappear, so that the frequency of lymphocyte translocations may decrease and reach the control level by the time the animals reach adulthood.

Identification of oogonial stem cells in chicken ovary

OBJECTIVES

Oogonial stem cells (OSCs) are germ cells that can sustain neo-oogenesis to replenish the pool of primary follicles in adult ovaries. In lower vertebrates, fresh oocytes are produced by numerous OSCs through mitosis and meiosis during each reproduction cycle, but the OSCs in adult mammals are rare. The birds have retained many conserved features and developed unique features of ovarian physiology during evolution, and the presence of OSCs within avian species remain unknown.

MATERIALS AND METHODS

In this study, we investigated the existence and function of OSCs in adult chickens. The chicken OSCs were isolated and expanded in culture. We then used cell transplantation system to evaluate their potential for migration and differentiation in vivo.

RESULTS

DDX4/SSEA1-positive OSCs were identified in both the cortex and medulla of the adult chicken ovary. These putative OSCs undergo meiosis in the reproductively active ovary. Furthermore, the isolated OSCs were expanded in vitro for months and found to express germline markers similar to those of primordial germ cells. When transplanted into the bloodstream of recipient embryos, these OSCs efficiently migrated into developing gonads, initiated meiosis, and then derived oocytes in postnatal ovaries.

CONCLUSIONS

This study has confirmed the presence of functional OSCs in birds for the first time. The identification of chicken OSCs has great potential for improving egg laying and preserving endangered species.

Ovarian aging: mechanisms and intervention strategies

Ovarian reserve is essential for fertility and influences healthy aging in women. Advanced maternal age correlates with the progressive loss of both the quantity and quality of oocytes. The molecular mechanisms and various contributing factors underlying ovarian aging have been uncovered. In this review, we highlight some of critical factors that impact oocyte quantity and quality during aging. Germ cell and follicle reserve at birth determines reproductive lifespan and timing the menopause in female mammals. Accelerated diminishing ovarian reserve leads to premature ovarian aging or insufficiency. Poor oocyte quality with increasing age could result from chromosomal cohesion deterioration and misaligned chromosomes, telomere shortening, DNA damage and associated genetic mutations, oxidative stress, mitochondrial dysfunction and epigenetic alteration. We also discuss the intervention strategies to delay ovarian aging. Both the efficacy of senotherapies by antioxidants against reproductive aging and mitochondrial therapy are discussed. Functional oocytes and ovarioids could be rejuvenated from pluripotent stem cells or somatic cells. We propose directions for future interventions. As couples increasingly begin delaying parenthood in life worldwide, understanding the molecular mechanisms during female reproductive aging and potential intervention strategies could benefit women in making earlier choices about their reproductive health.

Germline stem cells in human

The germline cells are essential for the propagation of human beings, thus essential for the survival of mankind. The germline stem cells, as a unique cell type, generate various states of germ stem cells and then differentiate into specialized cells, spermatozoa and ova, for producing offspring, while self-renew to generate more stem cells. Abnormal development of germline stem cells often causes severe diseases in humans, including infertility and cancer. Primordial germ cells (PGCs) first emerge during early embryonic development, migrate into the gentile ridge, and then join in the formation of gonads. In males, they differentiate into spermatogonial stem cells, which give rise to spermatozoa via meiosis from the onset of puberty, while in females, the female germline stem cells (FGSCs) retain stemness in the ovary and initiate meiosis to generate oocytes. Primordial germ cell-like cells (PGCLCs) can be induced in vitro from embryonic stem cells or induced pluripotent stem cells. In this review, we focus on current advances in these embryonic and adult germline stem cells, and the induced PGCLCs in humans, provide an overview of molecular mechanisms underlying the development and differentiation of the germline stem cells and outline their physiological functions, pathological implications, and clinical applications.

Identification of Stem Cell-Like Cells in the Ovary

Understanding the function of stem cells and cellular microenvironments in in vitro oogenesis, including ovarian folliculogenesis, is crucial for reproductive biology. Because mammalian females cannot generate oocytes after birth, the number of oocyte decreases with the progression of reproductive age. Meanwhile, there is an emerging need for the neogenesis of female germ cells to treat the increasing infertility-related issues in cancer survivors. The concept of oocytes neogenesis came from the promising results of stem cells in reproductive medicine. The stem cells that generate oocytes are defined as stem cell-like cells in the ovary (OSCs). Several recent studies have focused on the origin, isolation, and characteristic of OSCs and the differentiation of OSCs into oocytes, ovarian follicles and granulosa cells. Hence, in this review, we focus on the experimental trends in OSC research and discuss the methods of OSC isolation. We further summarized the characteristics of OSCs and discuss the markers used to identify OSCs differentiated from various cell sources. We believe that this review will be beneficial for advancing the research and clinical applications of OSCs.

The foundational framework of tumors: Gametogenesis, p53, and cancer

The completion-of-tumor hypothesis involved in the dynamic interplay between the initiating oncogenic event and progression is essential to better recognize the foundational framework of tumors. Here we review and extend the gametogenesis-related hypothesis of tumors, because high embryonic/germ cell traits are common in tumors. The century-old gametogenesis-related hypothesis of tumors postulated that tumors arise from displaced/activated trophoblasts, displaced (lost) germ cells, and the reprogramming/reactivation of gametogenic program in somatic cells. Early primordial germ cells (PGCs), embryonic stem (ES) cells, embryonic germ cells (EGCs), and pre-implantation embryos at the stage from two-cell stage to blastocysts originating from fertilization or parthenogenesis have the potential to develop teratomas/teratocarcinomas. In addition, the teratomas/teratocarcinomas/germ cells occur in gonads and extra-gonads. Undoubtedly, the findings provide strong support for the hypothesis. However, it was thought that these tumor types were an exception rather than verification. In fact, there are extensive similarities between somatic tumor types and embryonic/germ cell development, such as antigens, migration, invasion, and immune escape. It was documented that embryonic/germ cell genes play crucial roles in tumor behaviors, e.g. tumor initiation and metastasis. Of note, embryonic/germ cell-like tumor cells at different developmental stages including PGC and oocyte to the early embryo-like stage were identified in diverse tumor types by our group. These embryonic/germ cell-like cancer cells resemble the natural embryonic/germ cells in morphology, gene expression, the capability of teratoma formation, and the ability to undergo the process of oocyte maturation and parthenogenesis. These embryonic/germ cell-like cancer cells are derived from somatic cells and contribute to tumor formation, metastasis, and drug resistance, establishing asexual meiotic embryonic life cycle. p53 inhibits the reactivation of embryonic/germ cell state in somatic cells and oocyte-like cell maturation. Based on earlier and our recent studies, we propose a novel model to complete the gametogenesis-related hypothesis of tumors, which can be applied to certain somatic tumors. That is, tumors tend to establish a somatic asexual meiotic embryonic cycle through the activation of somatic female gametogenesis and parthenogenesis in somatic tumor cells during the tumor progression, thus passing on corresponding embryonic/germ cell traits leading to the malignant behaviors and enhancing the cells' independence. This concept may be instrumental to better understand the nature and evolution of tumors. We rationalize that targeting the key events of somatic pregnancy is likely a better therapeutic strategy for cancer treatment than directly targeting cell mitotic proliferation, especially for those tumors with p53 inactivation.

Ovarian Stem Cells (OSCs) from the Cryopreserved Ovarian Cortex: A Potential for Neo-Oogenesis in Women with Cancer-Treatment Related Infertility: A Case Report and a Review of Literature

Cancer treatment related infertility (CTRI) affects more than one third of young women undergoing anti-cancer protocols, inducing a premature exhaustion of the ovarian reserve. In addition to ovarian suppression by GnRHa, oocyte and cortex cryopreservation has gained interest in patients with estrogen-sensitive tumors for whom the hormonal burst to prompt the multiple follicular growth could provide a further pro-life tumor pulsing. On the other hand, cortex reimplantation implies a few drawbacks due to the unknown consistency of the follicles to be reimplanted or the risk of reintroducing malignant cells. The capability of ovarian stem cells (OCSs) from fresh ovarian cortex fragments to differentiate in vitro to mature oocytes provides a tool to overcome these drawbacks. In fact, since ovarian cortex sampling and cryopreservation is practicable before gonadotoxic treatments, the recruitment of OSCs from defrosted fragments could provide a novel opportunity to verify their suitability to be expanded in vitro as oocyte like cells (OLCs). Here, we describe in very preliminary experiments the consistency of an OSC population from a single cryopreserved ovarian cortex after thawing as well as both their viability and their suitability to be further explored in their property to differentiate in OLCs, thus reinforcing interest in stemness studies in the treatment of female CTRI.

Microplastics and Their Impact on Reproduction-Can we Learn From the C. elegans Model?

Biologically active environmental pollutants have significant impact on ecosystems, wildlife, and human health. Microplastic (MP) and nanoplastic (NP) particles are pollutants that are present in the terrestrial and aquatic ecosystems at virtually every level of the food chain. Moreover, recently, airborne microplastic particles have been shown to reach and potentially damage respiratory systems. Microplastics and nanoplastics have been shown to cause increased oxidative stress, inflammation, altered metabolism leading to cellular damage, which ultimately affects tissue and organismal homeostasis in numerous animal species and human cells. However, the full impact of these plastic particles on living organisms is not completely understood. The ability of MPs/NPs to carry contaminants, toxic chemicals, pesticides, and bioactive compounds, such as endocrine disrupting chemicals, present an additional risk to animal and human health. This review will discusses the current knowledge on pathways by which microplastic and nanoplastic particles impact reproduction and reproductive behaviors from the level of the whole organism down to plastics-induced cellular defects, while also identifying gaps in current knowledge regarding mechanisms of action. Furthermore, we suggest that the nematode Caenorhabditis elegans provides an advantageous high-throughput model system for determining the effect of plastic particles on animal reproduction, using reproductive behavioral end points and cellular readouts.

DDX4 + stem cells in the ovaries of postmenopausal women: existence and differentiation potential

Ovarian aging is a pacemaker with multiple organ dysfunction. Recently, stem cells with the ability to generate new oocytes have been identified, which provides the possibility of stem cell therapy for ovarian aging. Several studies have revealed the existence of stem cells in human postmenopausal ovary. In this study, we describe a new method using magnetic activated cell sorting combined with differential adhesion to isolate DDX4 + stem cells from ovaries of postmenopausal women and show that the cells exhibit similar gene expression profiles and growth characteristics with primitive germ cells. Furthermore, the DDX4 + stem cells could enter meiosis stage and differentiation into oocytes. The RNA-seq data of the differentiated oocytes shows that mitochondrial metabolism may play an important role in the oogenesis process of the DDX4 + stem cells. Through using human ovarian cortical fragments transplantation model, we indicated that the GFP-DDX4 + stem cells differentiated into some GFP positive oocyte-like structure in vivo. Our study provided a new method for the isolation of DDX4 + stem cells from the ovaries of postmenopausal women and confirmed the ability of these stem cells to differentiate into oocytes.

How Epigenetics Can Enhance Pig Welfare?

Epigenetics works as an interface between the individual and its environment to provide phenotypic plasticity to increase individual adaptation capabilities. Recently, a wide variety of epi-genetic findings have indicated evidence for its application in the development of putative epi-biomarkers of stress in farm animals. The purpose of this study was to evaluate previously reported stress epi-biomarkers in swine and encourage researchers to investigate potential paths for the development of a robust molecular tool for animal welfare certification. In this literature review, we report on the scientific concerns in the swine production chain, the management carried out on the farms, and the potential implications of these practices for the animals' welfare and their epigenome. To assess reported epi-biomarkers, we identified, from previous studies, potentially stress-related genes surrounding epi-biomarkers. With those genes, we carried out a functional enrichment analysis of differentially methylated regions (DMRs) of the DNA of swine subjected to different stress-related conditions (e.g., heat stress, intrauterine insult, and sanitary challenges). We identified potential epi-biomarkers for target analysis, which could be added to the current guidelines and certification schemes to guarantee and certify animal welfare on farms. We believe that this technology may have the power to increase consumers' trust in animal welfare.

Follicular development in livestock: Influencing factors and underlying mechanisms

Livestock farming development has become increasingly important in recent years. It not only provides us with meat nutrition and pet feeding but also increases the economic value by providing numerous employment opportunities, which improves our life quality. The livestock farming development depends on successful animal reproduction. As a vital process in animal reproduction, folliculogenesis and its influencing factors as well as their underlying mechanisms need to be understood thoroughly. This review is aimed at summarizing the factors such as cellular processes, gene regulation, noncoding RNAs and other endocrine or paracrine regulatory factors that affect follicular development, and their underlying mechanisms of action in livestock in order to provide novel insights for future studies. The above factors were found as significant determinants influencing the follicular development in livestock through various signaling pathways.

Role of Stem Cells in the Ovarian Tissue Cryopreservation and Transplantation for Fertility Preservation

Although the cancer survival rate has increased, cancer treatments, including chemotherapy and radiotherapy, can cause ovarian failure and infertility in women of reproductive age. Preserving fertility throughout cancer treatment is critical for maintaining quality of life. Fertility experts should propose individualized fertility preservation methods based on the patient’s marital status, pubertal status, partner status, and the urgency of treatment. Widely practiced fertility preservation methods, including ovarian transposition and embryo and oocyte cryopreservation, are inappropriate for prepubertal girls or those needing urgent initiation of cancer treatment. Ovarian tissue cryopreservation and transplantation, an emerging new technology, may be a solution for these cancer patients. The use of stem cells in ovarian tissue cryopreservation and transplantation increases oxygenation, angiogenesis, and follicle survival rates. This review discusses the recent advances in ovarian tissue cryopreservation and transplantation with special focus on the use of stem cells to improve fertilization techniques.

Tannic acid repair of zearalenone-induced damage by regulating the death receptor and mitochondrial apoptosis signaling pathway in mice

Zearalenone (ZEA) is an estrogenic toxin produced by Fusarium strains, that is widely present in crops, and endangers the reproductive system of animals. Tannic acid (TA) is a natural polyphenolic substance that is widespread in the roots, stems, and leaves of plants, and has special pharmacological activity. This study was designed to investigate the therapeutic effect of TA on ZEA-induced ovarian damage in mice and to explore the molecular mechanism involved. Ninety healthy Kunming female mice were divided into six equal groups. All the groups but the control group were administered daily with ZEA [10 mg/kg body weight (bw)] orally, for 7 days, to induce damage to the reproductive system. Some groups were also administered with TA (50, 100, and 200 mg/bw) for 7 days. Mice were euthanized 24 h later to allow for collection of serum and ovaries. TA can effectively alleviate the appearance of congestion and redness of the ovary, caused by ZEA, and increase the number of healthy growing follicles. Moreover, the estrogen content and the levels of MDA and ROS in the ovaries can be effectively reduced by TA. It can also reduce the apoptosis of ovarian cells, decreases the protein expression of the estrogen receptor, Fas, Fasl, caspase-3, caspase-8, caspase-9, and Bax, and increases the protein expression of Bcl-2. Our study indicates that TA reduces the strong estrogen and oxidative damage induced by ZEA, and these therapeutic effects may be partially mediated by the death receptor and mitochondrial apoptosis signaling pathway.

The effects of human umbilical cord mesenchymal stem cell transplantation on female fertility restoration in mice

BACKGROUND

Female fertility refers to the capacity to produce oocytes and achieve fertilization and pregnancy, and it is impaired by age, disease, environment and social pressure. However, no effective therapy that restores female reproductive ability has been established. Mesenchymal stromal cells (MSCs) exhibit multilineage differentiation potential and have attracted considerable attention as a tool for restoring female fertility.

METHODS

This study used human umbilical cord-MSCs (Huc-MSCs) to restore fertility in aging female mice and mice with chemotherapy-induced damage through the rescue of ovarian function and reconstruction of the fallopian tubes and uterus. In our study, two mouse models were generated: aging mice (35 weeks of age) and mice with chemotherapy-induced damage.

RESULTS

The effect of MSCs on the ovaries, fallopian tubes and uterus was evaluated by analyzing gonadal hormone levels and by performing morphological and statistical analyses. The levels of estradiol (E2) and follicle-stimulating hormone (FSH) exhibited significant recovery after Huc-MSC transplantation in both aging mice and chemotherapy-treated mice. Huc-MSC treatment also increased the number of primordial, developing and preovulatory follicles in the ovaries of mice. Moreover, MSCs were shown to rescue the morphology of the fallopian tubes and uterus through mechanisms such as cilia regeneration in the fallopian tubes and reformation of glands and endometrial tissue in the uterus.

CONCLUSION

Huc-MSCs may represent an effective treatment for restoring female fertility through recovery from chemotherapy-induced damage and rescue of female reproductive organs from the effects of aging.

Bone marrow-derived mesenchymal stem cells combined with gonadotropin therapy restore postnatal oogenesis of chemo-ablated ovaries in rats via enhancing very small embryonic-like stem cells

BACKGROUND

Very small embryonic-like stem cells (VSELs) are a rare population within the ovarian epithelial surface. They contribute to postnatal oogenesis as they have the ability to generate immature oocytes and resist the chemotherapy. These cells express markers of pluripotent embryonic and primordial germ cells.

OBJECTIVE

We aimed to explore the capability of VSELs in restoring the postnatal oogenesis of chemo-ablated rat ovaries treated with bone marrow-derived mesenchymal stem cells (BM-MSCs) combined with pregnant mare serum gonadotropin (PMSG).

METHODS

Female albino rats were randomly assigned across five groups: I (control), II (chemo-ablation), III (chemo-ablation + PMSG), IV (chemo-ablation + MSCs), and V (chemo-ablation + PMSG + MSCs). Postnatal oogenesis was assessed through measurement of OCT4, OCT4A, Scp3, Mvh, Nobox, Dazl4, Nanog, Sca-1, FSHr, STRA8, Bax, miR143, and miR376a transcript levels using qRT-PCR. Expression of selected key proteins were established as further confirmation of transcript expression changes. Histopathological examination and ovarian hormonal assessment were determined.

RESULTS

Group V displayed significant upregulation of all measured genes when compared with group II, III or IV. Protein expression confirmed the changes in transcript levels as group V displayed the highest average density in all targeted proteins. These results were confirmed histologically by the presence of cuboidal germinal epithelium, numerous primordial, unilaminar, and mature Graafian follicles in group V.

CONCLUSION

VSELs can restore the postnatal oogenesis in chemo-ablated ovaries treated by BM-MSCs combined with PMSG.

The Role of Stem Cells and Their Derived Extracellular Vesicles in Restoring Female and Male Fertility

Infertility is a globally recognized issue caused by different reproductive disorders. To date, various therapeutic approaches to restore fertility have been attempted including etiology-specific medication, hormonal therapies, surgical excisions, and assisted reproductive technologies. Although these approaches produce results, however, fertility restoration is not achieved in all cases. Advances in using stem cell (SC) therapy hold a great promise for treating infertile patients due to their abilities to self-renew, differentiate, and produce different paracrine factors to regenerate the damaged or injured cells and replenish the affected germ cells. Furthermore, SCs secrete extracellular vesicles (EVs) containing biologically active molecules including nucleic acids, lipids, and proteins. EVs are involved in various physiological and pathological processes and show promising non-cellular therapeutic uses to combat infertility. Several studies have indicated that SCs and/or their derived EVs transplantation plays a crucial role in the regeneration of different segments of the reproductive system, oocyte production, and initiation of sperm production. However, available evidence triggers the need to testify the efficacy of SC transplantation or EVs injection in resolving the infertility issues of the human population. In this review, we highlight the recent literature covering the issues of infertility in females and males, with a special focus on the possible treatments by stem cells or their derived EVs.

Pathways and factors regulated by bone marrow-derived stem cells in human ovarian tissue

OBJECTIVE

To describe molecular and paracrine signaling changes produced by human bone marrow-derived stem cells (BMDSC) in human ovarian cortex.

DESIGN

Experimental study.

SETTING

University hospital research laboratories.

PATIENT(S)

Ovarian cortex from poor responder women (n = 7).

ANIMALS

Immunodeficient NOD/SCID female mice (n = 18).

INTERVENTION(S)

Human ovarian cortex strips were xenografted into ovariectomized NOD/SCID female mice. A week later, mice were infused with phosphate-buffered saline, 1 × 106 BMDSC, or 3 × 105 CD133+ cells via tail vein. Gene expression changes and enriched pathways were assessed by RT2 Profiler Arrays. Several upregulated genes were validated in individual samples by real-time quantitative PCR, and transcriptomic results were reinforced by a proteomic assessment.

MAIN OUTCOME MEASURE(S)

Gene expression changes, enriched Kyoto Encyclopedia of Genes and Genomes pathways, and paracrine factors.

RESULT(S)

Seventy-four Kyoto Encyclopedia of Genes and Genomes pathways were upregulated, with the PI3K-Akt signaling pathway the most enriched after BMDSC and CD133 treatments. The greatest transcriptomic changes were seen on day 14 in the BMDSC group, affecting the regulation of paracrine factors such as KITLG, THBS1, SERPINF1, and TIMP2. Proteomics data verified changes in FoxO signaling, actin cytoskeleton remodeling, and apoptosis by BMDSC.

CONCLUSION(S)

We identified paracrine factors and pathways regulated by BMDSC that may be future targets of treatment for the increasing number of poor responder women. Our findings suggest that BMDSC upregulated soluble factors such as KITLG, THBS1, SERPINF1, and TIMP2 as well as PI3K-Akt signaling and regulation of actin cytoskeleton pathways. The identification of these putative underlying mechanisms informs future experiments aiming to optimizing clinical application of BMDSC.

Reproductive Longevity and Aging: Geroscience Approaches to Maintain Long-Term Ovarian Fitness

Increases in delayed childbearing worldwide have elicited the need for a better understanding of the biological underpinnings and implications of age-related infertility. In women 35 years and older the incidences of infertility, aneuploidy, and birth defects dramatically increase. These outcomes are a result of age-related declines in both ovarian reserve and oocyte quality. In addition to waning reproductive function, the decline in estrogen secretion at menopause contributes to multisystem aging and the initiation of frailty. Both reproductive and hormonal ovarian function are limited by the primordial follicle pool, which is established in utero and declines irreversibly until menopause. Because ovarian function is dependent on the primordial follicle pool, an understanding of the mechanisms that regulate follicular growth and maintenance of the primordial follicle pool is critical for the development of interventions to prolong the reproductive life span. Multiple pathways related to aging and nutrient-sensing converge in the mammalian ovary to regulate quiescence or activation of primordial follicles. The PI3K/PTEN/AKT/FOXO3 and associated TSC/mTOR pathways are central to the regulation of the primordial follicle pool; however, aging-associated systems such as the insulin-like growth factor-1/growth hormone pathway, and transsulfuration/hydrogen sulfide pathways may also play a role. Additionally, sirtuins aid in maintaining developmental metabolic competence and chromosomal integrity of the oocyte. Here we review the pathways that regulate ovarian reserve and oocyte quality, and discuss geroscience interventions that leverage our understanding of these pathways to promote reproductive longevity.

Novel Approaches in Addressing Ovarian Insufficiency in 2019: Are We There Yet?

Ovarian insufficiency is described as a multifaceted issue typically encountered in the field of assisted reproduction. The three main identified diagnoses of ovarian insufficiency include premature ovarian failure (POF), poor ovarian response (POR), and advanced maternal age (AMA). Patient heterogeneity in the era of individualized medicine drives research forward leading to the emergence of novel approaches. This plethora of innovative treatments in the service of adequately managing ovarian insufficiency is called to undertake the challenge of addressing infertile patients exploring their reproductive options. This review provides an all-inclusive presentation and critical analysis on novel treatments that have not achieved routine clinical practice status yet, but have recently emerged as promising. In light of the lack of randomized controlled trials conveying safety and efficiency, clinicians are left puzzled in addressing the "how" and "for whom" these approaches may be beneficial. From ovarian injection employing platelet-rich plasma (PRP) or stem cells to artificial gametes and ovaries, ovarian transplantation, and mitochondrial replacement therapy, this descriptive review provides insight toward assisting the practitioner in decision making regarding these cutting-edge treatments. Biological mechanisms, invasiveness levels, efficiency, as well as possible complications, the current status along with bioethical concerns are discussed in the context of identifying future optimal treatment.

Biomechanical Strain Promotes the Differentiation of Murine Oogonial Stem Cells

Cells within tissues are routinely subjected to physiological stress and strain, arising from direct interactions with neighboring cells as well as with extracellular matrix components. Accordingly, there is tremendous interest in deciphering how cells sense, and respond to, changes in biomechanical forces. In this study, we explored the effects of mechanostimulation on the differentiation of mouse female germline or oogonial stem cells (OSCs) as a model for adult stem cell function. We report that increasing levels, or repeated application of a subthreshold fixed level, of radial strain to OSCs in culture significantly increased rates of in vitro oocyte formation as a measure of stem cell differentiation. These responses involved changes in F-actin-mediated cytoskeletal tension as well as in activation of intracellular signaling by Rho-associated protein kinase (ROCK) and Yes-associated protein (YAP) phosphorylation. In addition, application of mechanical strain to OSCs enhanced association of YAP with muscle-specific cytidine-adenosine-thymidine (MCAT) response elements in the promoter stimulated by retinoic acid gene 8 (Stra8), the transcriptional activation of which is required for germline meiotic commitment. These data indicate that biomechanical strain directly promotes the differentiation of adult female germline stem cells through a signaling pathway involving F-actin, ROCK, YAP, and Stra8.

The Roles of Different Stem Cells in Premature Ovarian Failure

Premature ovarian failure (POF) is characterized by amenorrhea, hypergonadotropism and hypoestrogenism before the age of 40, which affects 1% of women in the general population. POF is complex and heterogeneous due to its pathogenetic mechanisms. It is one of the significant causes of female infertility. Although many treatments are available for POF, these therapies are less efficient and trigger many side effects. Therefore, to find effective therapeutics for POF is urgently required. Due to stem cells having self-renewal and regeneration potential, they may be effective for the treatment of ovarian failure and consequently infertility. Recent studies have found that stem cells therapy may be able to restore the ovarian structure and function in animal models of POF and provide an effective treatment method. The present review summarizes the biological roles and the possible signaling mechanisms of the different stem cells in POF ovary. Further study on the precise mechanisms of stem cells on POF may provide novel insights into the female reproduction, which not only enhances the understanding of the physiological roles but also supports effective therapy for recovering ovarian functions against infertility.

Germ cells of the mammalian female: A limited or renewable resource?

In many non-mammalian organisms, a population of germ-line stem cells supports continuing production of gametes during most or all the life of the individual, and germ-line stem cells are also present and functional in male mammals. Traditionally, however, they have been thought not to exist in female mammals, who instead generate all their germ cells during fetal life. Over the last several years, this dogma has been challenged by several reports, while supported by others. We describe and compare these conflicting studies with the aim of understanding how they came to opposing conclusions. We first consider studies that, by examining marker-gene expression, the fate of genetically marked cells, and consequences of depleting the oocyte population, addressed whether ovaries of post-natal females contain oogonial stem cells (OSC) that give rise to new oocytes. We next discuss whether ovaries contain cells that, even if inactive under physiological conditions, nonetheless possess OSC properties that can be revealed through cell-culture. We then examine studies of whether cells harvested after long-term culture of cells obtained from ovaries can, following transplantation into ovaries of recipient females, give rise to oocytes and offspring. Finally, we note studies where somatic cells have been re-programmed to acquire a female germ-cell fate. We conclude that the weight of evidence strongly supports the traditional interpretation that germ-line stem cells do not exist post-natally in female mammals. However, the ability to generate germ cells from somatic cells in vitro establishes a method to generate new gametes from cells of post-natal mammalian females.

Emerging follicular activation strategies to treat women with poor ovarian response and primary ovarian insufficiency

PURPOSE OF THE REVIEW

Female reproductive aging remains one of the key unsolved challenges in the field of reproductive medicine. This article reviews three of the most recent and cutting-edge strategies that are currently being investigated to address the issues of poor ovarian response (POR) and primary ovarian insufficiency (POI).

RECENT FINDINGS

Publications revealing the mechanism of mechanical disruption of the Hippo signaling pathway paved the way to studies on its potential application for fertility treatments. This, in combination with Akt stimulation, resulted in live births and ongoing pregnancies in women with POI. Building on previous reports on the effects of bone marrow transplants on fertility after chemotherapy, another approach involved autologous stem cell ovarian transplantation (ASCOT). The method proved effective in achieving live births in women previously diagnosed with POR. A third approach, intraovarian injection of autologous platelet-rich plasma, resulted in live births and ongoing pregnancies both spontaneously and via in vitro fertilization (IVF) in women with POI and POR.

SUMMARY

New paths are being charted to address the issues of POI and POR. Although these are preliminary studies that should be interpreted with caution, they represent great promise for the women affected by these conditions and the physicians treating them.

Regenerative Medicine Approaches in Bioengineering Female Reproductive Tissues

Diseases, disorders, and dysfunctions of the female reproductive tract tissues can result in either infertility and/or hormonal imbalance. Current treatment options are limited and often do not result in tissue function restoration, requiring alternative therapeutic approaches. Regenerative medicine offers potential new therapies through the bioengineering of female reproductive tissues. This review focuses on some of the current technologies that could address the restoration of functional female reproductive tissues, including the use of stem cells, biomaterial scaffolds, bio-printing, and bio-fabrication of tissues or organoids. The use of these approaches could also be used to address issues in infertility. Strategies such as cell-based hormone replacement therapy could provide a more natural means of restoring normal ovarian physiology. Engineering of reproductive tissues and organs could serve as a powerful tool for correcting developmental anomalies. Organ-on-a-chip technologies could be used to perform drug screening for personalized medicine approaches and scientific investigations of the complex physiological interactions between the female reproductive tissues and other organ systems. While some of these technologies have already been developed, others have not been translated for clinical application. The continuous evolution of biomaterials and techniques, advances in bioprinting, along with emerging ideas for new approaches, shows a promising future for treating female reproductive tract-related disorders and dysfunctions.

The role of gonadotropin-releasing hormone agonists in female fertility preservation

Advances in anticancer treatments have resulted in increasing survival rates among cancer patients. Accordingly, the quality of life after treatment, particularly the preservation of fertility, has gradually emerged as an essential consideration. Cryopreservation of embryos or unfertilized oocytes has been considered as the standard method of fertility preservation among young women facing gonadotoxic chemotherapy. Other methods, including ovarian suppression and ovarian tissue cryopreservation, have been considered experimental. Recent large-scale randomized controlled trials have demonstrated that temporary ovarian suppression using gonadotropin-releasing hormone agonists (GnRHa) during chemotherapy is beneficial for preventing chemotherapy-induced premature ovarian insufficiency in breast cancer patients. It should also be emphasized that GnRHa use during chemotherapy does not replace established fertility preservation methods. All young women facing gonadotoxic chemotherapy should be counseled about and offered various options for fertility preservation, including both GnRHa use and cryopreservation of embryos, oocytes, and/or ovarian tissue.

Premature ovarian insufficiency: pathogenesis and therapeutic potential of mesenchymal stem cell

Primary ovarian insufficiency (POI) is defined as a reduction in ovarian function before the expected age of menopause. POI is known to increase the risk of cardiovascular disorders, osteoporosis, cognitive decline, and mood disorders, resulting in a reduced quality of life. Appropriate hormone replacement for premenopausal women decreases these adverse health risks and improves quality of life for women with POI, but does not prolong life expectancy. The potential etiologies of POI include chromosomal abnormalities and genetic mutations, autoimmune factors, and iatrogenic causes, including surgery, chemotherapy, and radiation therapy. A major association is suggested to exist between reproductive longevity and the DNA damage pathway response genes. DNA damage and repair in ovarian granulosa cells is strongly associated with POI. Depletion of oocytes with damaged DNA occurs through different cell death mechanisms, such as apoptosis, autophagy, and necroptosis, mediated by the phosphatase and tensin homolog (PTEN)/phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/forkhead transcription factors 3 (FOXO3) pathway. Mesenchymal stem cells (MSCs) are characterized by the ability of self-renewal and differentiation and play an important role in the regeneration of injured tissues. Transplantation of MSCs has been shown to functionally restore ovarian reserve in a POI mouse model. Recent advances in stem cell therapy are likely to be translated to new therapeutic options bringing new hope to patients with POI. The aim of this review is to summarize the pathogenic mechanisms that involve cell death and DNA damage and repair pathways and to discuss the stem cell-based therapies as potential therapeutic options for this gynecologic pathology.

The different doses of radiation therapy-induced damage to the ovarian environment in rats

PURPOSE

The sequelae of premature loss of ovarian function can undoubtedly have undesirable effects for a woman although radiotherapy is one of the most relevant treatment modalities for various types of malignancies. The aim of this study was to determine the effect of different doses of radiation on ovarian folliculogenesis, inflammation, and apoptotic markers.

MATERIALS AND METHODS

For this purpose, 40 healthy Wistar albino female rats divided into four groups: 1) Control group; 2) those that were exposed to total body 1 Gy of gamma rays; 3) those that were exposed to the total body 5 Gy of gamma rays, and 4) those that were exposed to total body 10 Gy of gamma rays. External irradiation to the total body was given with gamma irradiation delivered by the Co60 teletherapy machine. The day after radiation application the rats were sacrificed and the ovaries were removed in all groups. Histopathologic examination, follicle counting, and classification were performed in the ovarian tissues. The expression of AMH, TNF-α, IL1-β, Bax, and Bcl-2 was detected. The stained sections were examined for caspase 3 positive apoptotic cell numbers.

RESULTS

The recorded results revealed that increased radiation dose induced obvious ovarian injuries that were indicated by histopathological, and immunohistochemical alterations, including elevation of ovarian injury markers. A significantly lower number of total and primordial follicles was detected with increasing radiation dose compared with the control group. According to our immunohistochemical results, 10 Gy of gamma rays group had the lowest AMH expression levels, while had the highest TNF-α, IL1-β expression level compared to the control group. When the groups were evaluated in terms of apoptosis, it was seen that the number of caspase 3 positive cells and Bax immunoreactivity intensity increased with radiation dose. In contrast, Bcl-2 immunoreactivity intensity decreased with increasing radiation dose compared with the control group.

CONCLUSIONS

We demonstrate here that dose rate plays an important role when estimating the relation between exposure to an increased dose of ionizing radiation and the risk of ovarian disease. According to these results, certain factors have to be optimized before introducing them into clinics.

Diminished Ovarian Reserve Chemotherapy-Induced Mouse Model: A Tool for the Preclinical Assessment of New Therapies for Ovarian Damage

Diminished ovarian reserve (DOR) and primary ovarian insufficiency (POI) are primary factors leading to infertility. However, there is a lack of appropriate animal models of DOR usable for assessing new therapeutic strategies. In this study, we aimed to evaluate whether chemotherapy treatment in mice could reproduce features similar of that observed in women with DOR. Twenty-one Nonobese diabetic/severe combined immunodeficiency (NOD/SCID) female mice were allocated to 3 groups (n = 7/group): control, single dose of vehicle (Dimethyl Sulfoxide [DMSO]); DOR, single reduced chemotherapy dose; and POI, single standard chemotherapy dose. After 21 days, mice underwent ovarian hyperstimulation and mating. Part of the animals were harvested to analyze ovarian reserve, ovulation and fertilization rates, and morphology, apoptosis, and vascularization of the ovarian stroma. The remaining mice underwent multiple matings to assess pregnancy rates and litter sizes. The DOR and POI mice showed an impaired estrous cyclicity and a decrease in ovarian mass, number of follicles, Metaphase II (MII) oocytes, and embryos as well as in ovarian stroma vascularization. Mice in both models showed also an increase in the percentage of morphologically abnormal follicles, stromal degeneration, and apoptosis. Similar to that observed in DOR and POI patients, these impairments were less severe in DOR than in POI mice. None of the POI females were able to achieve a pregnancy. Meanwhile, DOR females achieved several consecutive pregnancies, although litter size was decreased when compared to controls. In conclusion, a mouse model which displayed most of the ovarian characteristics and fertility outcomes of women with DOR has been established using a single dose of chemotherapy.

Microenvironmental changes induced by placenta-derived mesenchymal stem cells restore ovarian function in ovariectomized rats via activation of the PI3K-FOXO3 pathway

Background

Translational studies have explored the therapeutic potential and feasibility of mesenchymal stem cells (MSCs) in several degenerative diseases; however, mechanistic studies of the function of these cells have been insufficient. As ovarian failure causes anovulation as well as ovarian steroid hormonal imbalances, the specific aims of this study were to analyze the therapeutic role of placenta-derived MSCs (PD-MSCs) in an ovarian failure ovariectomy (OVX) rat model and evaluate whether PD-MSC transplantation (Tx) improved folliculogenesis and oocyte maturation in the injured ovary through PI3K/Akt and FOXO signaling.

Methods

Blood and ovary tissue were collected and analyzed after various PD-MSC Tx treatments in an ovariectomized rat model. Changes in the expression of folliculogenesis- and ovary regeneration-related genes induced by PD-MSC treatments were analyzed by qRT-PCR, Western blotting, and histological analysis.

Results

The levels of hormones related to ovary function were significantly increased in the PD-MSC Tx groups compared with those in the nontransplantation group (NTx). The follicle numbers in the ovarian tissues were increased along with the increased expression of genes related to folliculogenesis in the PD-MSC Tx groups compared with the NTx groups. Furthermore, Tx PD-MSCs induced follicle maturation by increasing the phosphorylation of GSK3 beta and FOXO3 (p < 0.05) and shifting the balance of growth and apoptosis in oocytes.

Conclusions

Taken together, these results show that PD-MSC Tx can restore ovarian function and induce ovarian folliculogenesis via the PI3K/Akt and FOXO signaling pathway.

Human umbilical cord mesenchymal stem cells restore the ovarian metabolome and rescue premature ovarian insufficiency in mice

Background

Premature ovarian insufficiency (POI) is an ovarian dysfunction that seriously affects a woman’s physiological health and reproduction. Mesenchymal stem cell (MSC) transplantation offers a promising treatment option for ovarian restoration in rodent POI models. However, the efficacy and mechanism of it remain unclear.

Methods

POI mice model was generated by cyclophosphamide and busulfan, followed with the treatment of tail-vein injection of the human umbilical cord mesenchymal stem cells (hUCMSCs). Maternal physiological changes and offspring behavior were detected. To reveal the pathogenesis and therapeutic mechanisms of POI, we first compared the metabolite profiles of healthy and POI ovarian tissues using untargeted metabolomics analyses. After stem cell therapy, we then collected the ovaries from control, POI, and hUCMSC-treated POI groups for lipid metabolomics and pseudotargeted metabolomics analysis.

Results

Our results revealed remarkable changes of multiple metabolites, especially lipids, in ovarian tissues after POI generation. Following the transplantation of clinical-grade hUCMSCs, POI mice exhibited significant improvements in body weight, sex hormone levels, estrous cycles, and reproductive capacity. Lipid metabolomics and pseudotargeted metabolomics analyses for the ovaries showed that the metabolite levels in the POI group, mainly lipids, glycerophospholipids, steroids, and amino acids changed significantly compared with the controls’, and most of them returned to near-healthy levels after receiving hUCMSC treatment. Meanwhile, we also observed an increase of monosaccharide levels in the ovaries from POI mice and a decrease after stem cell treatment.

Conclusions

hUCMSCs restore ovarian function through activating the PI3K pathway by promoting the level of free amino acids, consequently improving lipid metabolism and reducing the concentration of monosaccharides. These findings provide potential targets for the clinical diagnosis and treatment of POI.

Powering life through MitoTechnologies: exploring the bio-objectification of mitochondria in reproduction

Mitochondria, the organelles providing the cell with energy, have recently gained greater public visibility in the UK and beyond, through the introduction of two reproductive technologies which involve their manipulation, specifically ‘mitochondrial donation’ to prevent the maternal transmission of inherited disorders, and ‘Augment’ to improve egg quality and fertility. Focusing on these two ‘MitoTechnologies’ and mobilising the conceptual framework of “bio-objectification”, we examine three key processes whereby mitochondria are made to appear to have a life of their own: their transferability, their optimisation of life processes and their capitalisation. We then explore the implications of their bio-objectification in the bioeconomy of reproduction. Drawing on publicly available material collected in two research projects, we argue that mitochondria become a biopolitical agent by contributing to the redefinition of life as something that can be boosted at the cellular level and in reproduction. Mitochondria are now presented as playing a key role for a successful and healthy conception through the development and promotion of MitoTechnologies. We also show how their “revitalising power” is invested with great promissory capital, mainly deriving from their ethical and scientific biovalue in the case of mitochondrial donation, and from the logics of assetisation, in the case of Augment.

Pluripotent Stem (VSELs) and Progenitor (EnSCs) Cells Exist in Adult Mouse Uterus and Show Cyclic Changes Across Estrus Cycle

We have earlier reported pluripotent, very small embryonic-like stem cells (VSELs) and slightly bigger endometrial stem cells (EnSCs) in adult mouse uterus and their regulation by gonadotropin and steroid hormones. VSELs can differentiate into cells of all three lineages in vitro; however, they neither expand readily in vitro nor compliment a developing embryo. In the present study, a robust protocol is described to enrich uterine stem/progenitor cells along with their characterization and variation across estrus cycle. After enzymatic digestion of adult mouse uterus, single-cell suspension obtained was spun at 1000 rpm (250 g) to pellet majority of cells. Stem cells remain buoyant at this speed and were pelleted by spinning supernatant at 3000 rpm (1000 g). Spherical, darkly stained VSELs (2-6 μm) with high nucleo-cytoplasmic ratio and EnSCs (> 6 μm) expressed OCT-4, NANOG, SSEA-1, SCA-1, and c-KIT. OCT-4-positive cells co-expressed SSEA-1, ERα, ERβ, PR, and FSHR. Transcripts specific for pluripotent state (Oct-4, Oct-4a, Sox-2, Nanog), primordial germ cells (Stella, Fragilis), and receptors for pituitary and steroid hormones (ERα, ERβ, PR, FSHR 1 and 3) were studied by RT-PCR in 3000 rpm pellet. Cell pellet collected at 3000 rpm showed 10-fold enrichment of VSELs (2-6 μm, viable cells with surface phenotype of LIN-CD45-SCA-1+) by flow cytometry and upregulation of pluripotent transcripts by qRT-PCR compared with 1000 rpm pellet. VSELs were maximal during estrus and metestrus phases of estrus cycle. To conclude, VSELs/EnSCs can be enriched from adult uterus using the strategy described here, vary in numbers across estrus cycle, and are vulnerable to endocrine disruption as they express steroid receptors.

Isolation and Characterization of a Fetal-Maternal Microchimeric Stem Cell Population in Maternal Hair Follicles Long after Parturition

Fetal-maternal microchimerism describes the acquisition of fetal stem cells (FSC) by the mother during pregnancy and their long-term persistence after parturition. FSC may engraft in a variety of maternal tissues especially if there is organ/tissue injury, but their role and mechanism of persistence still remains elusive. Clinical applications due to their pluripotency, immunomodulatory effects and accessibility make them good candidates for ex-vivo manipulation and autologous therapies. The hair follicles contain a distinctive niche for pluripotent stem cells (PSC). To date, there is no published evidence of fetal microchimerism in the hair follicle. In our study, follicular unit extraction (FUE) technique allowed easy stem cell cultures to be obtained while simple hair follicle removal by pull-out technique failed to generate stem cells in culture. We identified microchimeric fetal stem cells within the primitive population of maternal stem cells isolated from the hair follicles with typical mesenchymal phenotype, expression of PSC genes and differentiation potential towards osteocytes, adypocites and chondrocytes. This is the first study to isolate fetal microchimeric stem cells in adult human hair long after parturition. We presume a sanctuary partition mechanism with PSC of the mother deposited during early embryogenesis could explain their long-term persistence.

Caffeic Acid Phenethyl Ester Effects: In Silico Study of its Osteoimmunological Mechanisms

Background:

Biological system complexity impedes the drug target identification by biological experiments. Thus drugs, rather than acting on target site only, can interact with the entire biological system. Study of this phenomenon, known as network pharmacology, provides grounds for biological target identification of new drugs or acts as a foundation for the discovery of new targets of present drugs. No publication is available on the interaction network of CAPE.

Aim:

This study was aimed at the investigation of the candidate targets and possible interactions of caffeic acid phenethyl ester (CAPE) involved in its osteoimmunological effects.

Methods:

This study encompasses the investigation of candidate targets and possible interactions of CAPE by analyzing through PASS Prediction and constructing a biological network of CAPE.

Results:

In response to input (CAPE), PASS Prediction generated a network of 1723 targets. While selecting the probability to be active (Pa) value greater than 0.7 brought forth only 27 targets for CAPE. Most of these targets predicted the therapeutic role of CAPE as an osteoimmunological agent. Apart from this, this network pharmacology also identified 10 potential anti-cancer targets for CAPE, out of which 7 targets have been used efficiently in developing potent osteoimmunological drugs.

Conclusion:

This study provides scientific prediction of the mechanisms involved in osteoimmunological effects of CAPE, presenting its promising use in the development of a natural therapeutic agent for the pharmaceutical industry. CAPE targets identified by web-based online databases and network pharmacology need additional in silico assessment such as docking and MD simulation studies and experimental verification to authenticate these results.

Estrogen regulation of germline stem cell differentiation as a mechanism contributing to female reproductive aging

Progressive loss of ovarian estrogen (E2) production is a hallmark feature of, if not a driving force behind, reproductive aging and the menopause. Recent genetic studies in mice have shown that female germline or oogonial stem cells (OSCs) contribute to maintenance of adult ovarian function and fertility under physiological conditions through support of de-novo oogenesis. Here we show that mouse OSCs express E2 receptor-α (ERα). In the presence of E2, ERα interacts with the stimulated by retinoic acid gene 8 (Stra8) promoter to drive Stra8 expression followed by oogenesis. Treatment of mice with E2 in vivo increases Stra8 expression and oogenesis, and these effects are nullified by ERα (Esr1), but not ERβ (Esr2), gene disruption. Although mice lacking ERα are born with a normal quota of oocytes, ERα-deficient females develop premature ovarian insufficiency in adulthood due to impaired oogenesis. Lastly, mice treated with reversible ER antagonists show a loss of Stra8 expression and oocyte numbers; however, both endpoints rebound to control levels after ceasing drug treatment. These findings establish a key physiological role for E2-ERα signaling in promoting OSC differentiation as a potential mechanism to maintain adequate numbers of ovarian follicles during reproductive life.

Efficiently accumulating germ-like stem cells from mouse postnatal ovary by in situ tissue culture

Although recent studies have revealed that germline stem cells (GSCs) exist in the mouse postnatal ovary, how to efficiently obtain GSCs for regenerating neo-oogenesis is still a technical challenge. Here, we report that using in situ tissue culture we can efficiently accumulate large amounts of proliferating germ-like cells from mouse postnatal ovaries. Usually, more than 10,000 germ-like cells can be derived from one ovary by this method, and over 20% of these cells can grow into germ-like cells with self-renewal, which thus can serve as a good cell pool to isolate GSCs by other cell assorting methods such as FACS. This method is simple and time-saving, which should be useful for in future studies on mouse GSCs.

In Vitro Generation of Oocytes from Ovarian Stem Cells (OSCs): In Search of Major Evidence

The existence of ovarian stem cells (OSCs) in women as well as their physiological role in post-menopausal age are disputed. However, accumulating evidence demonstrated that, besides the animal models including primarily mice, even in adult women putative OSCs obtained from ovarian cortex are capable to differentiate in vitro into oocyte-like cells (OLCs) expressing molecular markers typical of terminal stage of oogonial cell lineage. Recent studies describe that, similarly to mature oocytes, the OSC-derived OLCs also contain haploid karyotype. As proof of concept of their stem commitment, OSCs from mice differentiated to oocytes in vitro are suitable to be fertilized and implanted in sterilized animals resulting in embryo development. Despite enthusiasm for these data, which definitely require extended confirmation before considering potential application in humans for treatment of ovarian insufficiency, OSCs appear suitable for other clinical uses, restoring the endocrine derangements in premature ovarian failure or for fertility preservation in oncologic patients after anti-cancer treatments. In this context, the selection of viable oocytes generated from OSCs before chemotherapy protocols would overcome the potential adjunct oncogenic risk in women bearing hormone-dependent tumors who are repeatedly stimulated with high dose estrogens to induce oocyte maturation for their egg recruitment and cryopreservation.

Stem Cells, Self-Renewal, and Lineage Commitment in the Endocrine System

The endocrine system coordinates a wide array of body functions mainly through secretion of hormones and their actions on target tissues. Over the last decades, a collective effort between developmental biologists, geneticists, and stem cell biologists has generated a wealth of knowledge related to the contribution of stem/progenitor cells to both organogenesis and self-renewal of endocrine organs. This review provides an up-to-date and comprehensive overview of the role of tissue stem cells in the development and self-renewal of endocrine organs. Pathways governing crucial steps in both development and stemness maintenance, and that are known to be frequently altered in a wide array of endocrine disorders, including cancer, are also described. Crucially, this plethora of information is being channeled into the development of potential new cell-based treatment modalities for endocrine-related illnesses, some of which have made it through clinical trials.