In Vitro Activation Early Follicles: From the Basic Science to the Clinical Perspectives

ZnSO4 Protects against premature ovarian failure through PI3K/AKT/GSK3β signaling pathway

Zinc (Zn) is an essential trace element with anti-inflammatory and antioxidant effects and plays a crucial role in the female reproductive system. We aimed to investigate the protective effect of ZnSO4 on premature ovarian failure (POF) in SD rats and granulosa cells (GCs) treated with cisplatin. We also explored the underlying mechanisms. In vivo experiments showed that ZnSO4 increased the serum levels of Zn2+, increased estrogen (E2) secretion, and decreased follicle-stimulating hormone (FSH) secretion in rats. ZnSO4 increased ovarian index, protected ovarian tissues and blood vessels, reduced excessive follicular atresia, and maintained follicular development. At the same time, ZnSO4 inhibited apoptosis in the ovaries. In vitro experiments showed that ZnSO4 combination treatment restored the intracellular levels of Zn2+ and inhibited the apoptosis of GCs. ZnSO4 inhibited cisplatin-induced reactive oxygen species (ROS) production and preserved mitochondrial membrane potential (MMP). We also found that ZnSO4 protected against POF by activating the PI3K/AKT/GSK3β signaling pathway and reducing apoptosis of GCs. These data suggest that ZnSO4 may be a potential therapeutic agent for protecting the ovaries and preserving fertility during chemotherapy.

Therapeutic effects of human umbilical cord mesenchymal stem cell-derived extracellular vesicles on ovarian functions through the PI3K/Akt cascade in mice with premature ovarian failure

Premature ovarian failure (POF) mainly refers to ovarian dysfunction in females younger than forty. Mesenchymal stem cells (MSCs) are considered an increasingly promising therapy for POF. This study intended to uncover the therapeutic effects of human umbilical cord MSC-derived extracellular vesicles (hucMSCEVs) on POF. hucMSCs were identified by observing morphology and examining differentiation capabilities. EVs were extracted from hucMSCs and later identified utilizing nanoparticle tracking analysis, transmission electron microscopy, and Western blotting. POF mouse models were established by injecting D-galactose (Dgal). The estrous cycles were assessed through vaginal cytology, and serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), anti-mullerian hormone (AMH), estradiol (E2), and progesterone (P) were measured by ELISA. The human ovarian granulosa cell line KGN was used for in vitro experiments. The uptake of hucMSC-EVs by KGN cells was detected. After D-gal treatment, cell proliferation and apoptosis were assessed via CCK-8 assay and flow cytometry. The PI3K/Akt pathway-related proteins were determined by Western blotting. Our results revealed that POF mice had prolonged estrous cycles, increased FSH and LH levels, and decreased AMH, E2, and P levels. Treatment with hucMSC-EVs partially counteracted the above changes. D-gal treatment reduced proliferation and raised apoptosis in KGN cells, while hucMSC-EV treatment annulled the changes. D-gal-treated cells exhibited downregulated p-PI3K/PI3K and p-Akt/Akt levels, while hucMSC-EVs activated the PI3K/Akt pathway. LY294002 suppressed the roles of hucMSC-EVs in promoting KGN cell proliferation and lowering apoptosis. Collectively, hucMSC-EVs facilitate proliferation and suppress apoptosis of ovarian granulosa cells by activating the PI3K/Akt pathway, thereby alleviating POF.

Recent Insights into Noncoding RNAs in Primary Ovarian Insufficiency: Focus on Mechanisms and Treatments

CONTEXT

Primary ovarian insufficiency (POI) is a heterogeneous disease with an unknown underlying trigger or root cause. Recently many studies evaluated noncoding RNAs (ncRNAs), especially microRNAs (miRNAs), long noncoding RNA (lncRNAs), circular RNAs (circRNAs), and small interfering RNAs (siRNAs) for their associations with POI.

EVIDENCE ACQUISITION

In this review, we outline the biogenesis of various ncRNAs relevant to POI and summarize the evidence for their roles in the regulation of disease occurrence and progression. Articles from 2003 to 2022 were selected for relevance, validity, and quality from results obtained in PubMed and Google Scholar using the following search terms: noncoding RNAs; primary ovarian insufficiency; premature ovarian failure; noncoding RNAs and primary ovarian insufficiency/premature ovarian failure; miRNAs and primary ovarian insufficiency/premature ovarian failure; lncRNAs and primary ovarian insufficiency/premature ovarian failure; siRNAs and primary ovarian insufficiency/premature ovarian failure; circRNAs and primary ovarian insufficiency/premature ovarian failure; pathophysiology; and potential treatment. All articles were independently screened for eligibility by the authors.

EVIDENCE SYNTHESIS

This review summarizes the biological functions and synthesis of miRNAs, lncRNAs, siRNAs, and circRNAs in POI and discusses the findings of clinical and in vitro and in vivo studies. Although there is variability in the findings of individual studies, overall the available literature justifies the conclusion that dysregulated ncRNAs play significant roles in POI.

CONCLUSION

The potential of ncRNAs in the treatment of POI requires further investigation, as ncRNAs derived from mesenchymal stem cell-secreted exosomes play pivotal roles and have considerable therapeutic potential in a multitude of diseases.

From in vivo to in vitro: exploring the key molecular and cellular aspects of human female gametogenesis

Human oogenesis is a highly complex and not yet fully understood process due to ethical and technological barriers that limit studies in the field. In this context, replicating female gametogenesis in vitro would not only provide a solution for some infertility problems, but also be an excellent study model to better understand the biological mechanisms that determine the formation of the female germline. In this review, we explore the main cellular and molecular aspects involved in human oogenesis and folliculogenesis in vivo, from the specification of primordial germ cells (PGCs) to the formation of the mature oocyte. We also sought to describe the important bidirectional relationship between the germ cell and the follicular somatic cells. Finally, we address the main advances and different methodologies used in the search for obtaining cells of the female germline in vitro.

The Late Effects of Cancer Treatment on Female Fertility and the Current Status of Fertility Preservation-A Narrative Review

Fertility counseling should be offered to all individuals of young reproductive age early in the patient's trajectory following a cancer diagnosis. Systemic cancer treatment and radiotherapy often have an inherent gonadotoxic effect with the potential to induce permanent infertility and premature ovarian failure. For the best chances to preserve a patient's fertility potential and to improve future quality of life, fertility preservation methods should be applied before cancer treatment initiation, thus multidisciplinary team-work and timely referral to reproductive medicine centers specialized in fertility preservation is recommended. We aim to review the current clinical possibilities for fertility preservation and summarize how infertility, as a late effect of gonadotoxic treatment, affects the growing population of young female cancer survivors.

Iron overload triggering ECM-mediated Hippo/YAP pathway in follicle development: a hypothetical model endowed with therapeutic implications

Disruption of iron homeostasis plays a negative role in follicle development. The dynamic changes in follicle growth are dependent on Hippo/YAP signaling and mechanical forces. However, little is known about the liaison between iron overload and the Hippo/YAP signalling pathway in term of folliculogenesis. Here, based on the available evidence, we established a hypothesized model linking excessive iron, extracellular matrix (ECM), transforming growth factor-β (TGF-β) and Hippo/Yes-associated protein (YAP) signal regarding follicle development. Hypothetically, the TGF-β signal and iron overload may play a synergistic role in ECM production via YAP. We speculate that the dynamic homeostasis of follicular iron interacts with YAP, increasing the risk of ovarian reserve loss and may enhance the sensitivity of follicles to accumulated iron. Hence, therapeutic interventions targeting iron metabolism disorders, and Hippo/YAP signal may alter the consequences of the impaired developmental process based on our hypothesis, which provides potential targets and inspiration for further drug discovery and development applied to clinical treatment.

Comparison of mouse ovarian follicular development and gene expression in the presence of ovarian tissue extract and sodium selenite: An experimental study

Background

Ovarian tissue extract (OTE) and sodium selenite (SS) enhance the growth and maturation of preantral follicles in a dose-dependent manner.

Objective

The present study was designed to bring more information regarding the mechanism of OTE and SS on the mRNA expression of follicle-stimulating hormone receptors (FSHR) and the proliferation cell nuclear antigens (PCNA) of in vitro matured isolated follicles.

Materials and Methods

The tissue extract was prepared from adult ovaries. The preantral follicles (n = 266) were isolated from 12-16-day-old mice and cultured in the control, experimental I (10 ng/ml SS), and experimental II (OTE) groups for 12 days. The follicular diameter, survival, and maturation rates, also, the production of 17-β-estradiol and progesterone, and the follicular expression of PCNA and FSH receptor genes were analyzed.

Results

The survival rate of follicles in the SS-treated group (84.58%) was significantly higher than that OTE (75.63%; p = 0.023) and control (69.38%; p = 0.032) groups. The mean diameter of culture follicles in experimental group I (403.8 μm) and experimental group II (383.97 μm) increased significantly in comparison with the control group (342.05 μm; p = 0.032). The developmental rate of follicles, percentages of antrum formation, released metaphase II oocytes (p = 0.027; p = 0.019 respectively), production of hormones and the expression of 2 studied genes were significantly increased in both experimental groups in compare with control group (p = 0.021; p = 0.023 respectively).

Conclusion

The OTE and SS have a positive effect on development of mouse preantral follicles via over-expression of FSHR and PCNA genes.

Review: Role and regulatory mechanism of inhibin in animal reproductive system

Inhibin (INH) is a glycoprotein hormone secreted by the gonads that inhibit the synthesis and secretion of follicle-stimulating hormone (FSH). Increasing evidence indicates that INH plays a significant role in the development of the reproductive system including follicle development, ovulation rate, corpus luteum formation and ablation, steroid hormone synthesis and spermatogenesis, subsequently affecting the reproductive capacity of animals such as litter size and egg production. There are currently three main views on how INH inhibits FSH synthesis and secretion: influencing the activity of adenylate cyclase, the expression of follicle-stimulating hormone receptor or gonadotropin-releasing hormone receptor, and the competition system of inhibin-activin. This review discusses the current findings on the structure, function, and mechanism of action of INH in the reproductive system of animals.

Comprehensive proteomic profiling of early antral follicles from sheep

The present study evaluates the proteome of early antral follicles from Ovis aries. Fifty follicles were collected from ovaries of adult ewes and extracted proteins were trypsin-digested, desalted and analyzed by LC-MS/MS. Genes were screened for potential modulation by miRNAs and protein data, subjected to functional enrichment analysis. Label-free mass spectrometry allowed the identification of 2503 follicle proteins, confirming vimentin, actin, lamin, heat shock proteins and histones as the most abundant ones. In silico analyses indicated that miRNAs modulate the expression of genes coding proteins of the sheep follicles involved in cell cycle, cell differentiation, aging, apoptosis, cell death, adipocyte differentiation, cell division. The most important biological processes associated with the follicle proteins were innate immune response, translation, adaptive immune response and protein folding, while molecular functions linked to the proteome of sheep antral follicles related to metal ion binding, ATP binding, oxygen binding, RNA binding and GTP binding, among others. Upload of 2503 Uniport accession codes through DAVID platform matched 1274 genes, associated with translation, metabolic process, proteolysis involved in cellular protein catabolic process, zona pellucida receptor complex and others. KEEG pathways analysis indicated genes correlated with ovine follicular development, with major pathways listed as carbon metabolism, biosynthesis of amino acids, glutathione metabolism, oxidative phosphorylation, fatty acid degradation and oocyte meiosis. This represents a comprehensive atlas of proteins expressed in sheep early antral follicles and will contribute to future identification of biomarkers for follicular development and oocyte maturation.

Insulin Ameliorates Folliculogenesis in An Experimental Model of PCOS Mice

BACKGROUND

Insulin is an essential factor that controls female reproductive system. Insulin signaling via Foxo1 and Akt1 can improve steroidogenesis, cell proliferation, and protein synthesis. We aimed to determine the effect of insulin on possible changes in gene expression, hormonal status, and histological aspects of the ovary following the induction of the animal model of polycystic ovary syndrome (PCOS).

MATERIALS AND METHODS

In this experimental study, 24 adult female NMRI mice weighing 25-30 g were randomly placed in three groups: control, PCOS (60 mg/kg dehydroepiandrosterone (DHEA) for 20 days, and PCOS+insulin (60 mg/kg DHEA for 20 days+100 μL insulin diluted in water twice a week for 30 consecutive days). Blood specimens were obtained from the heart and the serum levels of testosterone, progesterone, and estradiol were measured. Right, and left ovaries were removed for real-time polymerase chain reaction (PCR) and stereological study.

RESULTS

DHEA injection significantly amplified the concentration of testosterone, progesterone, and estradiol. While insulin treatment amended the level of reproductive hormones. DHEA injection significantly reduced the expression levels of Irs1-4, Pdk1, Pi3k, and Akt1-3 and raised the expression level of Caspase-3. However, insulin administration amplified expression levels of Irs1-4, Pdk1, Pi3k, and Akt1-3, and reduced Caspase-3. The total volume of ovarian tissue in mice receiving DHEA significantly declined compared to the control group. Besides, a substantial decrease was detected in the number of ovarian antral, Graafian, and primordial follicles and also in the total number of corpus luteum following DHEA administration. Comparison of structural alterations in ovarian tissue between the PCOS+insulin and the PCOS groups displayed that insulin administration improved the total number of Graafian, primordial, and antral follicles and also corpus luteum.

CONCLUSION

In general, short-term insulin treatment showed improvement in hormonal balance, folliculogenesis, and insulin resistance in the ovaries of the PCOS mice model.

Cyclin-dependent kinase 6 (CDK6) as a potent regulator of the ovarian primordial-to-primary follicle transition

Introduction: Ovarian follicle development requires tight coordination between several factors to initiate folliculogenesis to generate a mature and fertile egg. Studies have shown that cell cycle factors might contribute to follicle development, hover specific knowledge on individual CDKs and follicle activation has not been investigated. Among cell cycle regulators, CDK6 is a key player through binding to cyclin D resulting DNA synthesis and genome duplication. Interestingly, the CDK6 gene is differentially expressed in oocytes and granulosa cells from human primordial and primary follicles, which suggest a potential role of CDK6 in the primordial-to-primary transition. In this study, we investigated the potential regulatory role of CDK6 in progression of primordial to primary follicle transition using BSJ-03-123 (BSJ), a CDK6-specific degrader. Methods: In mouse ovarian in vitro culture, BSJ reduced the activation of primordial follicles, and reduced follicle development. As a next step, we examined the egg maturation read-out and found that BSJ-treated follicles matured to competent MII eggs with resumption of first meiosis, comparable with the control group. Results: Noteworthy, it appears that inhibition of CDK6 did increase number of apotoptic cells, articular in the granulosa cells, but had no impact on ROS level of cultured ovaries compared to control group, indicating that the cells were not stressed. Oocyte quality thus appeared safe. Discussion: The results of this study indicate that CDK6 plays a role in the primordial-to-primary transition, suggesting that cell cycle regulation is an essential part of ovarian follicle development.

Genetic landscape of a large cohort of Primary Ovarian Insufficiency: New genes and pathways and implications for personalized medicine

Background

Primary Ovarian Insufficiency (POI), a public health problem, affects 1-3.7% of women under 40 yielding infertility and a shorter lifespan. Most causes are unknown. Recently, genetic causes were identified, mostly in single families. We studied an unprecedented large cohort of POI to unravel its molecular pathophysiology.

Methods

375 patients with 70 families were studied using targeted (88 genes) or whole exome sequencing with pathogenic/likely-pathogenic variant selection. Mitomycin-induced chromosome breakages were studied in patients’ lymphocytes if necessary.

Findings

A high-yield of 29.3% supports a clinical genetic diagnosis of POI. In addition, we found strong evidence of pathogenicity for nine genes not previously related to a Mendelian phenotype or POI: ELAVL2, NLRP11, CENPE, SPATA33, CCDC150, CCDC185, including DNA repair genes: C17orf53(HROB), HELQ, SWI5 yielding high chromosomal fragility. We confirmed the causal role of BRCA2, FANCM, BNC1, ERCC6, MSH4, BMPR1A, BMPR1B, BMPR2, ESR2, CAV1, SPIDR, RCBTB1 and ATG7 previously reported in isolated patients/families. In 8.5% of cases, POI is the only symptom of a multi-organ genetic disease. New pathways were identified: NF-kB, post-translational regulation, and mitophagy (mitochondrial autophagy), providing future therapeutic targets. Three new genes have been shown to affect the age of natural menopause supporting a genetic link.

Interpretation

We have developed high-performance genetic diagnostic of POI, dissecting the molecular pathogenesis of POI and enabling personalized medicine to i) prevent/cure comorbidities for tumour/cancer susceptibility genes that could affect life-expectancy (37.4% of cases), or for genetically-revealed syndromic POI (8.5% of cases), ii) predict residual ovarian reserve (60.5% of cases). Genetic diagnosis could help to identify patients who may benefit from the promising in vitro activation-IVA technique in the near future, greatly improving its success in treating infertility.

Funding

Université Paris Saclay, Agence Nationale de Biomédecine.

Immunolocalization of melatonin receptor type 1 in the sheep ovary and involvement of the PI3K/Akt/FOXO3a signaling pathway in the effects of melatonin on survival and in vitro activation of primordial follicles

This study characterized the expression of melatonin receptor type 1 (MT₁ ) protein in sheep ovaries, evaluated melatonin effects on primordial follicle survival and development after in vitro culture of ovarian tissue and verified the possible involvement of the phosphatidylinositol-3-kinase/protein kinase B/forkhead box O3a (PI3K/Akt/FOXO3a) pathway in the melatonin actions. Ovine ovarian fragments were cultured in α-modified minimum essential medium alone (α-MEM⁺ ) or supplemented with 100, 500, or 1000 pg/ml melatonin for 7 days. PI3K inhibition was performed through pretreatment of ovarian fragments with LY294002. Thereafter, immunohistochemistry was performed to evaluate the expression of cleaved caspase-3, Akt, phosphorylated-Akt, and phosphorylated-FOXO3a (p-FOXO3a). The immunohistochemical localization of the MT₁ receptor protein was documented in sheep preantral and antral follicles. After in vitro culture, 100 pg/ml melatonin showed higher follicular survival and activation than α-MEM⁺ and other melatonin concentrations. After PI3K inhibition, there was an increase in cleaved caspase-3-positive follicles, and a decrease in the primordial follicle activation, Akt phosphorylation, and nuclear exclusion of p-FOXO3a. In conclusion, MT₁ receptor protein is present in the sheep ovary. Furthermore, 100 pg/ml melatonin maintains survival and stimulates activation of primordial follicles through the PI3K/Akt/FOXO3a signaling pathway after in vitro culture of sheep ovarian tissue.

A synopsis of global frontiers in fertility preservation

Since 2007, the Oncofertility Consortium Annual Conference has brought together a diverse network of individuals from a wide range of backgrounds and professional levels to disseminate emerging basic and clinical research findings in fertility preservation. This network also developed enduring educational materials to accelerate the pace and quality of field-wide scientific communication. Between 2007 and 2019, the Oncofertility Consortium Annual Conference was held as an in-person event in Chicago, IL. The conference attracted approximately 250 attendees each year representing 20 countries around the world. In 2020, however, the COVID-19 pandemic disrupted this paradigm and precluded an in-person meeting. Nevertheless, there remained an undeniable demand for the oncofertility community to convene. To maintain the momentum of the field, the Oncofertility Consortium hosted a day-long virtual meeting on March 5, 2021, with the theme of "Oncofertility Around the Globe" to highlight the diversity of clinical care and translational research that is ongoing around the world in this discipline. This virtual meeting was hosted using the vFairs ® conference platform and allowed over 700 people to participate, many of whom were first-time conference attendees. The agenda featured concurrent sessions from presenters in six continents which provided attendees a complete overview of the field and furthered our mission to create a global community of oncofertility practice. This paper provides a synopsis of talks delivered at this event and highlights the new advances and frontiers in the fields of oncofertility and fertility preservation around the globe from clinical practice and patient-centered efforts to translational research.

Lithium treatment promotes the activation of primordial follicles through PI3K/Akt signaling

In mammals, dormant primordial follicles represent the ovarian reserve throughout reproductive life. In vitro activation of dormant primordial follicles has been used to treat patients with premature ovarian insufficiency (POI). However, there remains a lack of effective strategies to stimulate follicle activation in vivo. In this study, we used an in vitro ovarian culture system and intraperitoneal injection to study the effect of lithium treatment on primordial follicle activation. Lithium increased the number of growing follicles in cultured mouse ovaries and promoted pre-granulosa cell proliferation. Furthermore, lithium significantly increased the levels of phosphorylated protein kinase B (Akt) and the number of oocytes with forkhead Box O3a (FOXO3a) nuclear export. Inhibition of the phosphatidylinositol 3 kinase (PI3K)/Akt pathway by LY294002 reversed lithium-promoted mouse primordial follicle activation. These results suggest that lithium promotes mouse primordial follicle activation by the PI3K/Akt signaling. Lithium also promoted primordial follicle activation and increased the levels of p-Akt in mouse ovaries in vivo and in human ovarian tissue cultured in vitro. Taken together, lithium promotes primordial follicle activation in mice and humans by the PI3K/Akt signaling. Lithium might be a potential oral drug for treating infertility in POI patients with residual dormant primordial follicles.

Therapeutic Potential of In Vitro-Derived Oocytes for the Restoration and Treatment of Female Fertility

Considerable progress has been made with the development of culture systems for the in vitro growth and maturation (IVGM) of oocytes from the earliest-staged primordial follicles and from the more advanced secondary follicles in rodents, ruminants, nonhuman primates, and humans. Successful oocyte production in vitro depends on the development of a dynamic culture strategy that replicates the follicular microenvironment required for oocyte activation and to support oocyte growth and maturation in vivo while enabling the coordinated and timely acquisition of oocyte developmental competence. Significant heterogeneity exists between the culture protocols used for different stages of follicle development and for different species. To date, the fertile potential of IVGM oocytes derived from primordial follicles has been realized only in mice. Although many technical challenges remain, significant advances have been made, and there is an increasing consensus that complete IVGM will require a dynamic, multiphase culture approach. The production of healthy offspring from in vitro-produced oocytes in a secondary large animal species is a vital next step before IVGM can be tested for therapeutic use in humans.

Therapeutic options for premature ovarian insufficiency: an updated review

Primary ovarian insufficiency (POI) is a rare gynecological condition. This disease causes menstrual disturbances, infertility, and various health problems. Historically, hormone replacement therapy is the first-line treatment for this disorder. Women diagnosed with POI are left with limited therapeutic options. In order to remedy this situation, a new generation of therapeutic approaches, such as in vitro activation, mitochondrial activation technique, stem cell and exosomes therapy, biomaterials strategies, and platelet-rich plasma intra-ovarian infusion, is being developed. However, these emerging therapies are yet in the experimental stage and require precise design components to accelerate their conversion into clinical treatments. Thus, each medical practitioner bears responsibility for selecting suitable therapies for individual patients. In this article, we provide a timely analysis of the therapeutic strategies that are available for POI patients and discuss the prospects of POI therapy.

HGF Secreted by Mesenchymal Stromal Cells Promotes Primordial Follicle Activation by Increasing the Activity of the PI3K-AKT Signaling Pathway

Primordial follicle activation is fundamental for folliculogenesis and for the maintenance of fertility. An effective therapeutic strategy for patients with premature ovarian insufficiency (POI) is to promote the activation of residual primordial follicles. The secretome of human umbilical cord mesenchymal stromal cells (hUC-MSC-sec) contains several components that might promote the activation of primordial follicles. In the present study, we revealed that treatment with the hUC-MSC-sec significantly increased the proportion of activated primordial follicles in mouse ovaries both in vitro and in vivo. The activating effects of hUC-MSC-sec on primordial follicles were attributed to the activation of the PI3K-AKT signaling pathway by hepatocyte growth factor (HGF). While the effect of the hUC-MSC-sec was attenuated by the neutralizing antibodies against HGF, application of exogenous HGF alone also promoted the activation of primordial follicles. Furthermore, we demonstrated that HGF promoted the expression of KITL in granulosa cells by binding with the HGF receptor c-Met, thereby increasing the activity of the PI3K-AKT signaling pathway to activate primordial follicles. Taken together, our findings demonstrate that hUC-MSC-sec promotes primordial follicle activation through the functional component HGF to increase the PI3K-AKT signaling activity, highlighting the application of the hUC-MSC-sec or HGF for the treatment of POI patients.

Female Oncofertility: Current Understandings, Therapeutic Approaches, Controversies, and Future Perspectives

Recent advances in early detection and oncological therapies have ameliorated the survival rate of young cancer patients. Yet, ovarian impairment induced by chemotherapy and radiotherapy is still a challenging issue. This review, based on clinical and lab-based studies, summarizes the evidence of gonadotoxicity of chemoradiotherapy, the recent approaches, ongoing controversies, and future perspectives of fertility preservation (FP) in female patients who have experienced chemo- or radio-therapy. Existing data indicate that chemotherapeutic agents induce DNA alterations and massive follicle activation via the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway. Meanwhile, the radiation causes ionizing damage, leading to germ cell loss. In addition to the well-established methods, numerous therapeutic approaches have been suggested, including minimizing the follicle loss in cryopreserved ovarian grafts after transplantation, in vitro activation or in vitro growing of follicles, artificial ovarian development, or fertoprotective adjuvant to prevent ovarian damage from chemotherapy. Some reports have revealed positive outcomes from these therapies, whereas others have demonstrated conflictions. Future perspectives are improving the live birth rate of FP, especially in patients with adverse ovarian reserve, eliminating the risk of malignancy reintroducing, and increasing society’s awareness of FP importance.

The Roles of Luteinizing Hormone, Follicle-Stimulating Hormone and Testosterone in Spermatogenesis and Folliculogenesis Revisited

Spermatogenesis and folliculogenesis involve cell–cell interactions and gene expression orchestrated by luteinizing hormone (LH) and follicle-stimulating hormone (FSH). FSH regulates the proliferation and maturation of germ cells independently and in combination with LH. In humans, the requirement for high intratesticular testosterone (T) concentration in spermatogenesis remains both a dogma and an enigma, as it greatly exceeds the requirement for androgen receptor (AR) activation. Several data have challenged this dogma. Here we report our findings on a man with mutant LH beta subunit (LHβ) that markedly reduced T production to 1–2% of normal., but despite this minimal LH stimulation, T production by scarce mature Leydig cells was sufficient to initiate and maintain complete spermatogenesis. Also, in the LH receptor (LHR) knockout (LuRKO) mice, low-dose T supplementation was able to maintain spermatogenesis. In addition, in antiandrogen-treated LuRKO mice, devoid of T action, the transgenic expression of a constitutively activating follicle stimulating hormone receptor (FSHR) mutant was able to rescue spermatogenesis and fertility. Based on rodent models, it is believed that gonadotropin-dependent follicular growth begins at the antral stage, but models of FSHR inactivation in women contradict this claim. The complete loss of FSHR function results in the complete early blockage of folliculogenesis at the primary stage, with a high density of follicles of the prepubertal type. These results should prompt the reassessment of the role of gonadotropins in spermatogenesis, folliculogenesis and therapeutic applications in human hypogonadism and infertility.

The Role of Noncoding RNA in the Pathophysiology and Treatment of Premature Ovarian Insufficiency

Premature ovarian insufficiency (POI) is defined as a loss of ovarian function before the age of 40 years, with a prevalence rate estimated at approximately 1%. It causes infertility and is related to serious long-term health consequences, including reduced life expectancy, increased cardiovascular risk, decreased bone mineral density and neurological disorders. There is currently no effective therapy for POI that is widely available in clinical practice; therefore, the treatment of patients with POI is based on hormone replacement therapy. One of the recent advances in the understanding of the pathophysiology of POI has been the role of microRNAs (miRNAs) and other noncoding RNAs (ncRNAs) in the disease. Moreover, intensive research on human folliculogenesis and reproductive biology has led to the development of novel promising therapeutic strategies with the use of exosomal miRNAs derived from mesenchymal stem cells to restore ovarian function in POI patients. This narrative review focuses on the new studies concerning the role of ncRNAs in the pathogenesis of POI, together with their potential as biomarkers of the disease and targets for therapy.

Current Understandings of Core Pathways for the Activation of Mammalian Primordial Follicles

The mammalian ovary has two main functions-producing mature oocytes for fertilization and secreting hormones for maintaining the ovarian endocrine functions. Both functions are vital for female reproduction. Primordial follicles are composed of flattened pre-granulosa cells and a primary oocyte, and activation of primordial follicles is the first step in follicular development and is the key factor in determining the reproductive capacity of females. The recent identification of the phosphatidylinositol 3 kinase (PI3K)/phosphatase and tensin homolog deleted on chromosome 10 (PTEN) signaling pathway as the key controller for follicular activation has made the study of primordial follicle activation a hot research topic in the field of reproduction. This review systematically summarizes the roles of the PI3K/PTEN signaling pathway in primordial follicle activation and discusses how the pathway interacts with various other molecular networks to control follicular activation. Studies on the activation of primordial follicles have led to the development of methods for the in vitro activation of primordial follicles as a treatment for infertility in women with premature ovarian insufficiency or poor ovarian response, and these are also discussed along with some practical applications of our current knowledge of follicular activation.