Origin of germ cells and formation of new primary follicles in adult human ovaries

Making a good egg: human oocyte health, aging, and in vitro development

Mammalian eggs (oocytes) are formed during fetal life and establish associations with somatic cells to form primordial follicles that create a store of germ cells (the primordial pool). The size of this pool is influenced by key events during the formation of germ cells and by factors that influence the subsequent activation of follicle growth. These regulatory pathways must ensure that the reserve of oocytes within primordial follicles in humans lasts for up to 50 years, yet only approximately 0.1% will ever be ovulated with the rest undergoing degeneration. This review outlines the mechanisms and regulatory pathways that govern the processes of oocyte and follicle formation and later growth, within the ovarian stroma, through to ovulation with particular reference to human oocytes/follicles. In addition, the effects of aging on female reproductive capacity through changes in oocyte number and quality are emphasized, with both the cellular mechanisms and clinical implications discussed. Finally, the details of current developments in culture systems that support all stages of follicle growth to generate mature oocytes in vitro and emerging prospects for making new oocytes from stem cells are outlined.

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.

Isolation of Female Germline Stem Cells from Mouse and Human Ovaries by Differential Adhesion

Spermatogonial stem cell (SSC) counterparts known as female germline stem cells (fGSCs) were found in the mammalian ovary in 2004. Although the existence of fGSCs in the mammalian postnatal ovary is still under controversy, fGSC discovery encourages investigators to better understand the various aspects of these cells. However, their existence is not accepted by all scientists in the field because isolation of fGSCs by fluorescent activated cell sorting (FACS) has not been reproducible. In this study, we used differential adhesion to isolate and enrich fGSCs from mouse and human ovaries and subsequently cultured them in vitro. fGSCs were able to proliferate in vitro and expressed germ cell-specific markers Vasa, Dazl, Blimp1, Fragilis, Stella, and Oct4, at the protein level. Moreover, mouse and human fGSCs were, respectively, cultured for more than four months and one month in culture. Both mouse and human fGSCs maintained the expression of germ cell-specific markers over these times. In vitro cultured fGSCs spontaneously produced oocyte-like cells (OLCs) which expressed oocyte-relevant markers. Our results demonstrated that differential adhesion allows reproducible isolation of fGSCs that are able to proliferate in vitro over time. This source of fGSCs can serve as a suitable material for studying mechanisms underlying female germ cell development and function.

Artificial Oocyte: Development and Potential Application

Millions of people around the world suffer from infertility, with the number of infertile couples and individuals increasing every year. Assisted reproductive technologies (ART) have been widely developed in recent years; however, some patients are unable to benefit from these technologies due to their lack of functional germ cells. Therefore, the development of alternative methods seems necessary. One of these methods is to create artificial oocytes. Oocytes can be generated in vitro from the ovary, fetal gonad, germline stem cells (GSCs), ovarian stem cells, or pluripotent stem cells (PSCs). This approach has raised new hopes in both basic research and medical applications. In this article, we looked at the principle of oocyte development, the landmark studies that enhanced our understanding of the cellular and molecular mechanisms that govern oogenesis in vivo, as well as the mechanisms underlying in vitro generation of functional oocytes from different sources of mouse and human stem cells. In addition, we introduced next-generation ART using somatic cells with artificial oocytes. Finally, we provided an overview of the reproductive application of in vitro oogenesis and its use in human fertility.

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.

Enhanced method to select human oogonial stem cells for fertility research

Alternative methods to obtain mature oocytes are still needed for women with premature ovarian failure (POF). Oogonial stem cells (OSCs), found in adult ovaries, have provided insight into potential paths to treating infertility. Previously, the DDX4 antibody marker alone was utilized to isolate OSCs; however, extensive debate over its location in OSCs versus resulting oocytes (transmembrane or intracytoplasmic) has raised doubt about the identity of these cells. Separate groups, however, have efficiently isolated OSCs using another antibody marker Ifitm3 which is consistently recognized to be transmembrane in location. We hypothesized that by using anti-DDX4 and anti-IFITM3 antibodies, in combination, with MACS, we would improve the yield of isolated OSCs versus using anti-DDX4 antibodies alone. Our study supports earlier findings of OSCs in ovaries during the entire female lifespan: from reproductive age through post-menopausal age. MACS sorting ovarian cells using a the two-marker combination yielded a ~ twofold higher percentage of OSCs from a given mass of ovarian tissue compared to existing single marker methods while minimizing the debate surrounding germline marker selection. During in vitro culture, isolated cells retained the germline phenotype expression of DDX4 and IFITM3 as confirmed by gene expression analysis, demonstrated characteristic germline stem cell self-assembly into embryoid bodies, and formed > 40 µm "oocyte-like" structures that expressed the early oocyte markers GDF9, DAZL, and ZP1. This enhanced and novel method is clinically significant as it could be utilized in the future to more efficiently produce mature, secondary oocytes, for use with IVF/ICSI to treat POF patients.

Heterogeneity and Dynamics of Vasculature in the Endocrine System During Aging and Disease

The endocrine system consists of several highly vascularized glands that produce and secrete hormones to maintain body homeostasis and regulate a range of bodily functions and processes, including growth, metabolism and development. The dense and highly vascularized capillary network functions as the main transport system for hormones and regulatory factors to enable efficient endocrine function. The specialized capillary types provide the microenvironments to support stem and progenitor cells, by regulating their survival, maintenance and differentiation. Moreover, the vasculature interacts with endocrine cells supporting their endocrine function. However, the structure and niche function of vasculature in endocrine tissues remain poorly understood. Aging and endocrine disorders are associated with vascular perturbations. Understanding the cellular and molecular cues driving the disease, and age-related vascular perturbations hold potential to manage or even treat endocrine disorders and comorbidities associated with aging. This review aims to describe the structure and niche functions of the vasculature in various endocrine glands and define the vascular changes in aging and endocrine disorders.

The role of Chito-oligosaccharide in regulating ovarian germ stem cells function and restoring ovarian function in chemotherapy mice

In recent years, the discovery of ovarian germ stem cells (OGSCs) has provided a new research direction for the treatment of female infertility. The ovarian microenvironment affects the proliferation and differentiation of OGSCs, and immune cells and related cytokines are important components of the microenvironment. However, whether improving the ovarian microenvironment can regulate the proliferation of OGSCs and remodel ovarian function has not been reported. In this study, we chelated chito-oligosaccharide (COS) with fluorescein isothiocyanate (FITC) to track the distribution of COS in the body. COS was given to mice through the best route of administration, and the changes in ovarian and immune function were detected using assays of organ index, follicle counting, serum estrogen (E₂) and anti-Mullerian hormone (AMH) levels, and the expression of IL-2 and TNF-α in the ovaries. We found that COS significantly increased the organ index of the ovary and immune organs, reduced the rate of follicular atresia, increased the levels of E₂ and AMH hormones, and increased the protein expression of IL-2 and TNF-α in the ovary. Then, COS and OGSCs were co-cultured to observe the combination of COS and OGSCs, and measure the survival rate of OGSCs. With increasing time, the fluorescence intensity of cells gradually increased, and the cytokines IL-2 and TNF-α significantly promoted the proliferation of OGSCs. In conclusion, COS could significantly improve the ovarian and immune function of chemotherapy model mice, and improve the survival rate of OGSCs, which provided a preliminary blueprint for further exploring the mechanism of COS in protecting ovarian function.

Evaluation of safety, feasibility and efficacy of intra-ovarian transplantation of autologous adipose derived mesenchymal stromal cells in idiopathic premature ovarian failure patients: non-randomized clinical trial, phase I, first in human

Background

Premature ovarian failure (POF) is characterized by the loss of ovarian activity before the age of 40 years. Stem cell therapy has the capability to create a regenerative microenvironment and is a proposed treatment for POF-related infertility due to the presence of renewal folliculogenesis and germ cells in the adult ovaries. In this study, we assessed the safety, feasibility, efficacy and dose adjustment of autologous adipose-derived stromal cells (ADSCs) and their ability to improve ovarian function in POF patients.

Methods

This study was a non-randomized clinical trial, phase I. Nine women with a definitive diagnosis of POF were divided into three groups (n = 3 per group) that received either 5 × 10⁶, 10 × 10⁶, or 15 × 10⁶ autologous ADSCs suspension transplanted in the one ovary. Participants were followed-up at 24 h after the transplantation, and at 1 and 2 weeks, and 1, 2, 3, 6, and 12 months after the transplantation. The primary objective was to evaluate the safety of ADSCs transplantation. Secondary objectives included the effects of ADSCs transplantation on the resumption of menstruation, hormones level (Follicle-stimulating hormone (FSH) and anti-Müllerian hormone), ovarian function (Antral follicle count and ovary volume by ultrasonography evaluation) as well as dose escalation.

Results

Participants had not shown any early-onset possible side effects and secondary complications during follow-up. The menstruation resumption was observed in four patients which established for several months. In the 15 × 10⁶ group, two POF patients had a return of menstruation second months after the intervention. Two other POF patients in 5 × 10⁶ and 10 × 10⁶ cell groups reported menstruation resumption at 1 month after the intervention. We observed decreased serum FSH levels of less than 25 IU/l in four patients. In two patients in 5 × 10⁶ and 10 × 10⁶ cell groups, serum FSH showed an inconsistent decline during a 1 year follow up after ADSCs transplantation. The ovarian volume, AMH, and AFC were variable during the follow-up and no significant differences between cell groups (p > 0.05).

Conclusions

We showed the intra-ovarian embedding of ADSCs is safe and feasible and is associated with an inconsistent decline in serum FSH. This should be further investigated with a large RCT.

Trial registration

NCT02603744, Registered 13 November 2015 - Retrospectively registered, http://www.Clinicaltrials.gov

Ovarian Cancer Stem Cells: Newer Horizons

The ovarian cancer is one of the frequent cancers among women being diagnosed after cervical and breast cancer. The CA ovary is dreaded because even after successful treatment of the primary malignancy, the disease comes back and becomes resistant to conventional management. The prognosis in ovarian cancer management is mostly unsatisfactory, maybe because of the presence of ovarian cancer stem cells (OCSC). The hypothesis is that OCSC causes the recurrence of the ovarian malignancy. The OCSC can be identified by the presence of different markers and marker combinations. The assumptions are that CD44+, CD24+, CD117+, CD133+ and ALDH1+ could be the markers of ovarian cancer stem cells. The epithelial ovarian malignancy if proved as a stem cell disease, then it changes the entire management scenarios. Maybe, this will be the first step in managing the ovarian malignancy in the future.

Optimizing The Cell Seeding Protocol to Human Decellularized Ovarian Scaffold: Application of Dynamic System for Bio-Engineering

Objective

Decellularized tissue scaffolds provide an extracellular matrix to control stem cells differentiation toward specific lineages. The application of mesenchymal stem cells for artificial ovary production may enhance ex vivo functions of the ovary. On the other hand, the scaffold needs interaction and integration with cells. Thus, the development of ovarian engineered constructs (OVECs) requires the use of efficient methods for seeding of the cells into the ovarian and other types of scaffolds. The main goal of the present study was to develop an optimized culture system for efficient seeding of peritoneum mesenchymal stem cells (PMSCs) into human decellularized ovarian scaffold.

Materials and Methods

In this experimental study, three methods were used for cellular seeding including rotational (spinner flask) and static (conventional and injection) seeding cultures. OVECs were evaluated with Hematoxylin and Eosin staining and viability analyses for the seeded PMSCs. Then, immunohistochemistry analysis was performed using the best method of cellular seeding for primordial germ cell-like cells, mesenchymal stem cells and proliferation markers. Stereology analysis was also performed for the number of penetrated cells into the OVECs.

Results

Our results showed that rotational seeding increases the permeability of PMSCs into the scaffold and survival rate of the seeded PMSCs, comparing to the other methods. On the other hand, rotationally seeded PMSCs had a more favorable capability of proliferation with Ki67 expression and differentiation to ovarian specific cells with expression of primordial germ cell line markers without mesenchymal stem cells markers production. Furthermore, stereology showed a more favorable distribution of PMSCs along the outer surfaces of the OVEC with further distribution at the central part of the scaffold. The average total cell values were determined 2142187 cells/mm³ on each OVEC.

Conclusion

The rotational seeding method is a more favorable approach to cell seeding into ovarian decellularized tissue than static seeding.

Hard and soft X-ray imaging to resolve human ovarian cortical structures

Laboratory and synchrotron X-ray tomography are powerful tools for non-invasive studies of biological samples at micrometric resolution. In particular, the development of phase contrast imaging is enabling the visualization of sample details with a small range of attenuation coefficients, thus allowing in-depth analyses of anatomical and histological structures. Reproductive medicine is starting to profit from these techniques, mainly applied to animal models. This study reports the first imaging of human ovarian tissue where the samples consisted of surgically obtained millimetre fragments, properly fixed, stained with osmium tetroxide and included in epoxydic resin. Samples were imaged by the use of propagation phase contrast synchrotron radiation micro-computed tomography (microCT), obtained at the SYRMEP beamline of Elettra light source (Trieste, Italy), and X-ray absorption microCT at the Theoretical Biology MicroCT Imaging Laboratory in Vienna, Austria. The reconstructed microCT images were compared with the soft X-ray absorption and phase contrast images acquired at the TwinMic beamline of Elettra in order to help with the identification of structures. The resulting images allow the regions of the cortex and medulla of the ovary to be distinguished, identifying early-stage follicles and visualizing the distribution of blood vessels. The study opens to further application of micro-resolved 3D imaging to improve the understanding of human ovary's structure and support diagnostics as well as advances in reproductive technologies.

Female Fertility Preservation through Stem Cell-based Ovarian Tissue Reconstitution In Vitro and Ovarian Regeneration In Vivo

Historically, approaches designed to offer women diagnosed with cancer the prospects of having a genetically matched child after completion of their cytotoxic treatments focused on the existing oocyte population as the sole resource available for clinical management of infertility. In this regard, elective oocyte and embryo cryopreservation, as well as autologous ovarian cortical tissue grafting posttreatment, have gained widespread support as options for young girls and reproductive-age women who are faced with cancer to consider. In addition, the use of ovarian protective therapies, including gonadotropin-releasing hormone agonists and sphingosine-1-phosphate analogs, has been put forth as an alternative way to preserve fertility by shielding existing oocytes in the ovaries in vivo from the side-effect damage caused by radiotherapy and many chemotherapeutic regimens. This viewpoint changed with the publication of now numerous reports that adult ovaries of many mammalian species, including humans, contain a rare population of oocyte-producing germ cells-referred to as female germline or oogonial stem cells (OSCs). This new line of study has fueled research into the prospects of generating new oocytes, rather than working with existing oocytes, as a novel approach to sustain or restore fertility in female cancer survivors. Here, we overview the history of work from laboratories around the world focused on improving our understanding of the biology of OSCs and how these cells may be used to reconstitute "artificial" ovarian tissue in vitro or to regenerate damaged ovarian tissue in vivo as future fertility-preservation options.

Determination of the effects of bone marrow derived mesenchymal stem cells and ovarian stromal stem cells on follicular maturation in cyclophosphamide induced ovarian failure in rats

OBJECTIVE

Chemotherapy causes depletion of primordial follicles that leads to premature ovarian failure in female cancer survivals. We investigated the effect of bone marrow derived mesenchymal (BMMSCs) and ovarian stromal stem cells (OSSCs) on follicle maturation in chemotherapy induced ovarian failure.

MATERIAL AND METHODS

Thirty six Wistar Albino female rats were divided into three groups. Cyclophosphamide at a dose of 200 mg/kg was intraperitoneally (IP) given to the rats in all groups two times. 4 × 10⁶ BMMSCs (IP) was injected to the group-2 and 4 × 10⁶ OSSCs (IP) was injected to the group-3. Serum Anti-Müllerian Hormone (AMH) levels was determined with ELISA and primordial follicles were counted for investigation of primordial follicle reserve. The ovarian structure were evaluated histomorphologically. Localization of BrdU labeled stem cells, the expression of the cell cycle regulator p34Cdc2, gap junction protein p-connexin43 and intraovarian regulators of folliculogenesis Bone Morphogenic Protein 6 and 15 (BMP-6 and BMP-15) were investigated by immunohistochemistry.

RESULTS

The immunstaining of BMP-6 was higher in oocytes of group-3 more than group-1 and group-2. The immunpositivity of p34cdc2 and BMP-15 were also higher in follicular cells of group-3 than the other groups. The presence of p-connexin43 in group-3 was determined more than group-1 and group-2. The ovarian follicles with normal histological structure were observed just in group-3. Although, The AMH levels were decreased in rats from all groups at the end of experimental procedure the primordial follicle counts in group-3 was significantly higher than group-1.

CONCLUSION

Our findings suggest that OSSCs have more protective effect on follicle maturation than BMMSCs in cyclophosphamide induced ovarian damage.

Autologous mitochondrial transfer as a complementary technique to intracytoplasmic sperm injection to improve embryo quality in patients undergoing in vitro fertilization-a randomized pilot study

OBJECTIVE

To study if autologous mitochondrial transfer (AUGMENT) improves outcome in patients with previously failed in vitro fertilization (IVF).

DESIGN

Randomized, controlled, triple-blind, experimental study.

SETTING

Private infertility center, Valencian Institute of Infertility (IVI-RMA), Valencia, Spain.

PATIENT(S)

Infertile women ≤42 years of age, body mass index <30 kg/m², antimüllerian hormone ≥4 pmol/L, >5 million/mL motile sperm, at least one previous IVF with at least five metaphase oocytes (MIIs) collected, and low embryo quality.

INTERVENTIONS(S)

An ovarian cortex biopsy was performed to isolate egg precursor cells to obtain their mitochondria. Sibling MIIs were randomly allocated to AUGMENT (experimental) or intracytoplasmic sperm injection (Control). In AUGMENT, mitochondrial suspension was injected along with the sperm. Viable blastocysts from both groups were biopsied for preimplantation genetic testing for aneuploidy.

MAIN OUTCOME MEASURE(S)

Pregnancy, embryo quality.

RESULT(S)

An interim analysis was conducted. The patients' mean age was 36.3 ± 3.6 years, and they had an average of 2.5 ± 1.5 previous IVF cycles. Two of the 59 enrolled patients spontaneously conceived (one miscarried). Fifty-seven patients had ovarian biopsies and underwent stimulation. Oocyte retrieval was performed in 56 patients (premature ovulation; n = 1). A total of 253 MIIs were inseminated in AUGMENT and 250 in Control; fertilization rates were 62.7 ± 30.0% and 68.7 ± 29.1%, respectively. Statistical differences were observed in day 5 blastocyst formation rates (23.3 ± 32.0% vs. 41.1 ± 36.9%). Neither the euploid rate per biopsied blastocyst (43.8 ± 41.7% vs. 63.8 ± 44.1%) nor the euploid rate per MII (9.8 ± 20.5% vs. 11.9 ± 16.1%) between AUGMENT and Control achieved statistical significance. Moreover, no differences were seen regarding mitochondrial DNA content and relevant morphokinetic variables. Thirty patients were able to undergo embryo transfer. Cumulative live birth rates per transferred embryo were 41.6% in AUGMENT and 41.2% in Control.

CONCLUSION(S)

AUGMENT does not seem to improve prognosis in this population. Therefore, the study has been discontinued.

CLINICAL TRIAL REGISTRATION NUMBER

NCT02586298.

Does migrative and proliferative capability of epithelial cells reflect cellular developmental competence?

Mammalian epithelial and epithelial-like cells are significantly involved in various processes associated with tissue development, differentiation and oncogenesis. Because of that, high number of research is focused on identifying cells that express stem-like or progenitor characteristics. Identifying such cells and recognizing their specific markers, would open new clinical opportunities in transplantology and oncology. There are several epithelia characterized by their ability to rapidly proliferate and/or differentiate. Due to their function or location they are subject to cyclic changes involving processes of apoptosis and regeneration. Literature presenting well-structured studies of these types of epithelia was analyzed in order to compare various results and establish if epithelial cells’ migrative and proliferative ability indicates their stemness potential. Endometrial, ovarian, oviductal and oral mucosal epithelia were analyzed with most of the publications delivering relatively unified results. The ability to rapidly proliferate/differentiate usually indicated the presence of some kind of stem/stem-like/progenitor cells. Most of the papers focused on pinpointing the exact location of these kind of cells, or analyzing specific markers that would be used for their future identification. There have also been substantial proportion of research that focused on discovering growth factors or intercellular signals that induced proliferation/differentiation in analyzed epithelia. Most of the research provided valuable insights into the modes of function and characteristics of the analyzed tissue, outlining the importance of such study for the possible clinical application of in vitro derived cell cultures.

Improved Isolation, Proliferation, and Differentiation Capacity of Mouse Ovarian Putative Stem Cells

The recent discovery of ovarian stem cells in postnatal mammalian ovaries, also referred to as putative stem cells (PSCs), and their roles in mammalian fertility has challenged the long-existing theory that women are endowed with a certain number of germ cells. The rare amount of PSCs is the major limitation for utilizing them through different applications. Therefore, this study was conducted in six phases to find a way to increase the number of Fragilis- and mouse vasa homolog (MVH)-positive sorted cells from 14-day-old NMRI strain mice. Results showed that there is a population of Fragilis- and MVH-positive cells with pluripotent stem cell characteristics, which can be isolated and expanded for months in vitro. PSCs increase their proliferation capacity under the influence of some mitogenic agents, and our results showed that different doses of stem cell factor (SCF) induce PSC proliferation with the maximum increase observed at 50 ng/mL. SCF was also able to increase the number of Fragilis- and MVH-positive cells after sorting by magnetic-activated cell sorting and enhance colony formation efficiency in sorted cells. Differentiation capacity assay indicated that there is a basic level of spontaneous differentiation toward oocyte-like cells during 3 days of culture. However, relative gene expression was significantly higher in the follicle-stimulating hormone-treated groups, especially in the Fragilis- sorted PSCs. We suggest that higher number of PSCs provides us either a greater source of energy that can be injected into energy-impaired oocytes in women with a history of repeat IVF failure or a good source for research.

Neo-oogenesis in mammals

Recently, the existence of a mechanism for neo-oogenesis in the ovaries of adult mammals has generated much controversy within reproductive biology. This mechanism, which proposes that the ovary has cells capable of renewing the follicular reserve, has been described for various species of mammals. The first evidence was found in prosimians and humans. However, these findings were not considered relevant because the predominant dogma for reproductive biology at the time was that of Zuckerman. This dogma states that female mammals are born with finite numbers of oocytes that decline throughout postnatal life. Currently, the concept of neo-oogenesis has gained momentum due to the discovery of cells with mitotic activity in adult ovaries of various mammalian species (mice, humans, rhesus monkeys, domestic animals such as pigs, and wild animals such as bats). Despite these reports, the concept of neo-oogenesis has not been widely accepted by the scientific community, generating much criticism and speculation about its accuracy because it has been impossible to reproduce some evidence. This controversy has led to the creation of two positions: one in favour of neo-oogenesis and the other against it. Various animal models have been used in support of both camps, including both classic laboratory animals and domestic and wild animals. The aim of this review is to critically present the current literature on the subject and to evaluate the arguments pro and contra neo-oogenesis in mammals.

Expression of the Bone Morphogenetic Protein-2 (BMP2) in the Human Cumulus Cells as a Biomarker of Oocytes and Embryo Quality

BACKGROUND

The members of the transforming growth factor-B superfamily, as the bone morphogenetic proteins (BMPs) subfamily and anti-Müllerian hormone (AMH), play a role during follicular development, and the bone morphogenetic protein-2 (BMP2), AMH, and THY1 are expressed in ovaries.

AIM

This study was designed to define whether or not the expressions of these proteins in human cumulus cells (CCs) can be used as predictors of the oocyte and embryo competence.

SETTINGS AND DESIGN

The study included nine female patients who were diagnosed as idiopathic infertility, aged 25-33 years (median 30 years) and underwent Assisted Reproductive Technologies.

MATERIALS AND METHODS

The CCs from 60 oocyte-cumulus complexes obtained from the nine patients were evaluated with immunofluorescence staining in respect of BMPs, AMH and THY1 markers. The CCs surrounding the same oocytes were evaluated separately according to the oocyte and embryo quality.

STATISTICAL ANALYSIS

Quantitative data were statistically analyzed for differences using the two-sided Mann-Whitney U test (P < 0.05).

RESULTS AND CONCLUSIONS

Significant differences in immunofluorescence staining were observed in oocyte quality and embryo quality for the BMP2 only (P < 0.05). No significant differences were observed for AMH or CD90/THY1.

CONCLUSION

These results demonstrated that there is a significant difference in the expression of BMP2 in the CCs of good quality oocytes and subsequently a good embryo.

Oocyte stem cells: fact or fantasy?

For many decades, the dogma prevailed that female mammals had a finite pool of oocytes at birth and this was gradually exhausted during a lifetime of reproductive function. However, in 2004, a new era began in the field of female oogenesis. A study was published that appeared to detect oocyte-stem cells capable of generating new eggs within mouse ovaries. This study was highly controversial and the years since this initial finding have produced extensive research and even more extensive debate into their possibility. Unequivocal evidence testifying to the existence of oocyte-stem cells (OSCs) has yet to be produced, meanwhile the spectrum of views from both sides of the debate are wide-ranging and surprisingly passionate. Although recent studies have presented some convincing results that germ cells exist and are capable of creating new oocytes, many questions remain. Are these cells present in humans? Do they exist in physiological conditions in a dormant state? This comprehensive review first examines where and how the dogma of a finite pool was established, how this has been challenged over the years and addresses the most pertinent questions as to the current status of their existence, their role in female fertility, and perhaps most importantly, if they do exist, how can we harness these cells to improve a woman's oocyte reserve and treat conditions such as premature ovarian insufficiency (POI: also known as premature ovarian failure, POF).

Mitochondria during sea urchin oogenesis

Sea urchin represents an ideal model for studies on fertilization and early development, but the achievement of egg competence and mitochondrial behaviour during oogenesis remain to be enlightened. Oocytes of echinoid, such as sea urchin, unlike other echinoderms and other systems, complete meiotic maturation before fertilization. Mitochondria, the powerhouse of eukaryotic cells, contain a multi-copy of the maternally inherited genome, and are involved directly at several levels in the reproductive processes, as their functional status influences the quality of oocytes and contributes to fertilization and embryogenesis. In the present paper, we report our latest data on mitochondrial distribution, content and activity during Paracentrotus lividus oogenesis. The analyses were carried out using confocal microscopy, in vivo incubating oocytes at different maturation stages with specific probes for mitochondria and mtDNA, and by immunodetection of Hsp56, a well known mitochondrial marker. Results show a parallel rise of mitochondrial mass and activity, and, especially in the larger oocytes, close to germinal vesicle (GV) breakdown, a considerable increase in organelle activity around the GV, undoubtedly for an energetic aim. In the mature eggs, mitochondrial activity decreases, in agreement with their basal metabolism. Further and significant information was achieved by studying the mitochondrial chaperonin Hsp56 and mtDNA. Results show a high increase of both Hsp56 and mtDNA. Taken together these results demonstrate that during oogenesis a parallel rise of different mitochondrial parameters, such as mass, activity, Hsp56 and mtDNA occurs, highlighting important tools in the establishment of developmental competence.

Involvement of blood mononuclear cells in the infertility, age-associated diseases and cancer treatment

Blood mononuclear cells consist of T cells and monocyte derived cells. Beside immunity, the blood mononuclear cells belong to the complex tissue control system (TCS), where they exhibit morphostatic function by stimulating proliferation of tissue stem cells followed by cellular differentiation, that is stopped after attaining the proper functional stage, which differs among various tissue types. Therefore, the term immune and morphostatic system (IMS) should be implied. The TCS-mediated morphostasis also consists of vascular pericytes controlled by autonomic innervation, which is regulating the quantity of distinct tissues in vivo. Lack of proper differentiation of tissue cells by TCS causes either tissue underdevelopment, e.g., muscular dystrophy, or degenerative functional failures, e.g., type 1 diabetes and age-associated diseases. With the gradual IMS regression after 35 years of age the gonadal infertility develops, followed by a growing incidence of age-associated diseases and cancers. Without restoring an altered TCS function in a degenerative disease, the implantation of tissue-specific stem cells alone by regenerative medicine can not be successful. Transfused young blood could temporarily restore fertility to enable parenthood. The young blood could also temporarily alleviate aging diseases, and this can be extended by substances inducing IMS regeneration, like the honey bee propolis. The local and/or systemic use of honey bee propolis stopped hair and teeth loss, regressed varicose veins, improved altered hearing, and lowered high blood pressure and sugar levels. Complete regression of stage IV ovarian cancer with liver metastases after a simple elaborated immunotherapy is also reported.

Oogonial Precursor Cell-Derived Autologous Mitochondria Injection to Improve Outcomes in Women With Multiple IVF Failures Due to Low Oocyte Quality: A Clinical Translation

BACKGROUND

Mitochondrial dysfunction has been suggested as a major cause of age-induced decline in oocyte quality. In the past, donor oocyte cytoplasmic transfer showed some success but was abandoned due to the concerns with heteroplasmy. Recent studies indicated presence of oogonial precursor cells (OPCs) in the human ovary, which could be an autologous source of "healthy mitochondria." We sought to investigate the clinical efficacy of OPC-derived autologous mitochondrial injection (AMI) to improve oocyte quality in women with multiple in vitro fertilization (IVF) failures.

METHODS

The OPCs were isolated from laparoscopically obtained ovarian cortical pieces by cell sorting using a monoclonal anti-vasa homolog (anti-DDX) antibody. They were then disrupted and mitochondria were isolated. Reconstituted mitochondria were injected into each oocyte during intracytoplasmic sperm injection. Paired comparisons were made between the first failed cycles and the post-AMI cycles.

RESULTS

Of the 15 women undergoing ovarian stimulation, 2 were canceled and 3 decided to pool oocytes for later AMI. In remaining 10 (mean age 34.7 ± 4.1), AMI significantly improved fertilization rates (49.7 ± 31.3 vs 78.3 ± 18.9; P = .03) with a trend for better embryo grades (2.3 ± 0.3 vs 3.1 ± 0.7; P = .08). Four of 10 women conceived after single frozen embryo transfer and 3 after confirmation of diploidy via array comparative genomic hybridization (aCGH) (clinical pregnancy/embryo transfer = 4/10).

CONCLUSION

These data show encouraging results for AMI in comparison to previous failed IVF cycles.

Used protocols for isolation and propagation of ovarian stem cells, different cells with different traits

Although existence of ovarian stem cells (OSCs) in mammalian postnatal ovary is still under controversy, however, it has been almost accepted that OSCs are contributing actively to folliculogenesis and neo-oogenesis. Recently, various methods with different efficacies have been employed for OSCs isolation from ovarian tissue, which these methods could be chosen depends on aim of isolation and accessible equipments and materials in lab. Although isolated OSCs from different methods have various traits and characterizations, which might become from their different nature and origin, however these stem cells are promising source for woman infertility treatment or source of energy for women with a history of repeat IVF failure in near future. This review has brought together and summarized currently used protocols for isolation and propagation of OSCs in vitro.

Review Article: Stem Cells in Human Reproduction

The derivation of human embryonic stem (hES) cells heralds a new era in stem cell research, generating excitement for their therapeutic potential in regenerative medicine. Pioneering work of embryologists, developmental biologists, and reproductive medicine practitioners in in vitro fertilization clinics has facilitated hES cell research. This review summarizes current research focused on optimizing hES cell culture conditions for good manufacturing practice, directing hES cell differentiation toward trophectoderm and germ cells, and approaches used to reprogram cells for pluripotent cell derivation. The identification of germ stem cells in the testis and the recent controversy over their existence in the ovary raise the possibility of harnessing them for treating young cancer survivors. There is also the potential to harvest fetal stem cells with pluripotent cell-like properties from discarded placental tissues. The recent identification of adult stem/progenitor cell activity in the human endometrium offers a new understanding of common gynecological diseases. Discoveries resulting from research into embryonic, germ, fetal, and adult stem cells are highly relevant to human reproduction.

The effect of the immune system on ovarian function and features of ovarian germline stem cells

In addition to its role in maintaining organism homeostasis, the immune system also plays a crucial role in the modulation of ovarian function, as it regulates ovarian development, follicular maturation, ovulation and the formation of the corpus luteum. Ovarian germline stem cells are pluripotent stem cells derived from the ovarian cortex that can differentiate into ovarian germ cells and primary granulosa cells. Recent work has demonstrated that the proliferation and differentiation of ovarian germline stem cells is regulated in part by immune cells and their secreted factors. This paper reviews the role of the immune system in the regulation of ovarian function, the relationship between immune components and ovarian germline stem cells and current research efforts in this field.

Doxorubicin and cisplatin induce apoptosis in ovarian stromal cells obtained from cryopreserved human ovarian tissue

AIM

To investigate mechanisms by which doxorubicin (DOX) and cisplatin (CIS) cause human ovarian stroma injury.

PATIENTS & METHODS

Stromal cells from human cryopreserved ovarian tissue were cultured in the presence of 1 µM DOX and 10 µM CIS. Ovarian damage induced by treatments was evaluated by 'Live/Dead' and sulforhodamine-B assays, the expression of different apoptosis markers.

RESULTS

Stromal cell growth was inhibited by DOX and CIS, and this effect was accompanied by apoptosis through mitochondrial pathway activation: Bax, cleaved-caspase 9, cleaved-PARP1 induction and Akt1, Bcl2, phospho-44/42-MAPK/ERK1/2 reduction were observed.

CONCLUSION

DOX and CIS induced apoptosis in human ovarian stromal cells. Knowledge of mechanisms by which the drugs act is important to identify possible ways to counteract side effects of chemotherapy on ovaries.

Human umbilical cord blood-mesenchymal stem cells transplantation renovates the ovarian surface epithelium in a rat model of premature ovarian failure: Possible direct and indirect effects

This study aimed to isolate mesenchymal stem cells (MSC) from human umbilical cord blood (HCB) and to explore their influence on the ovarian epithelium after paclitaxel-induced ovarian failure. Ninety-five rats were divided into 6 groups: control, paclitaxel, paclitaxel and saline, HCB-MSC-treated for 2 weeks, HCB-MSC-treated for 4 weeks, and HCB-MSC-treated for 6 weeks. HCB cells were studied for CD34, CD44, and Oct ¾ using flow cytometry. Serum levels of FSH and E2 were measured using ELISA, RT-PCR analysis for human gene; beta-actin (ACTB), immunohistochemical analysis for CK 8/18, TGF-ß, PCNA and CASP-3 were performed. We found that ACTB gene was expressed in all rats' ovaries received HCB-MSC. After 4 weeks of transplantation, there was significant reduction in FSH, elevation in E2 levels, stabilization of the surface epithelium morphostasis, an increase in the antral follicle count and increase in integrated densities (ID) of CK 8/18, TGF-ß, and PCNA expressions and decrease in ID of CASP-3 expression. We concluded that HCB-MSC can restore the ovarian function after paclitaxel injection through a direct triggering effect on the ovarian epithelium and/or indirect enrichment of ovarian niche through regulating tissue expression of CK 8/18, TGF-ß and PCNA. These molecules are crucial in regulating folliculogenesis and suppressing CASP-3-induced apoptosis.

Overexpression of Oct4 in porcine ovarian stem/stromal cells enhances differentiation of oocyte-like cells in vitro and ovarian follicular formation in vivo

Background

Recent findings have revealed that the female gonad may have regenerative activity with having germ line stem cells in juveniles and adults. Application of these germ line stem cells could be an alternative therapy for reproductive disorders in regenerative medicine.

Methods

To enhance the potency of differentiation into oocyte-like cells (OLCs) and folliculogenesis, we overexpressed Oct4 in ovarian stem/stromal cell (OvSCs) and examined the cellular properties related to stemness and self-renewal ability and finally demonstrated the ability of in vitro differentiation and folliculogenesis.

Results

Ovarian cortex included putative stem cells in terms of AP activity, cell cycle status, cell proliferation, expression of mesenchymal lineage surface markers and pluripotent transcriptional markers. Further, Oct4 transfected OvSCs (Oct4-OvSCs) were enhanced their AP activity and cell proliferation compared to OvSCs. The potential on in vitro differentiation into OLCs and in vivo folliculogenesis was also evaluated in OvSCs and Oct4-OvSCs, respectively. Oct4-OvSCs possessed higher oogenesis potential in vitro than OvSCs, in terms of expression of germ cell markers by RT-PCR and the number of OLCs. When OvSCs and Oct4-OvSCs were xeno-transplanted into infertile mice ovaries, the OvSCs transplantation induced new primary follicle formation and hormonal levels of estradiol and FSH remained similar to that of normal mice. However, Oct4-OvSCs possessed higher ability for folliculogenesis based on inducing developing follicles with thecal layer and granulosa cells and more similar estradiol level to normal mice.

Conclusions

These findings demonstrated that putative stem cells were present in ovarian cortex and exhibited differentiation ability into OLCs and folliculogenesis in vivo, and Oct4-overexpression enhanced these ability, suggesting their cellular models based on gene therapy in understanding the mechanisms of oogenesis and folliculogenesis, and finally in view of reproductive cell therapy.

VSELs may obviate cryobanking of gonadal tissue in cancer patients for fertility preservation

Background

Infertility is an undesirable side effect and gonadal tissue banking is advocated in young cancer patients who are unable to preserve embryos or gametes prior to oncotherapy to achieve biological parenthood later on. Banking gonadal tissue is challenging and protocols to mature gametes in vitro are not yet clinically established. Transplanting ovarian cortical tissue at hetero-or orthotopic sites in women and bone marrow transplantation (BMT) in both men and women has resulted in spontaneous recovery of fertility, pregnancy and live births. Various studies in humans and mice suggest that genetic origin of offspring after BMT is similar to transplanted patient and not the donor. Thus the source of oocytes/sperm which result in spontaneous pregnancies still remains contentious.

Findings

Very small embryonic-like stem cells (VSELs) have been reported in adult human testis and ovary, in azoospermic testicular biopsies from survivors of childhood cancer and also in women with premature ovarian failure and menopause. VSELs survive chemotherapy because of their quiescent nature and can be detected in chemoablated mice gonads at protein and mRNA level and also by flow cytometry. Surviving VSELs spontaneously differentiate into oocyte-like structures and sperm when inhibitory factors are overcome in vitro. Transplantation of mesenchymal cells (isolated from different sources) has led to regeneration of chemoablated mouse gonads and also live births. Spermatogenesis is also restored from endogenous stem cells on inter-tubular transplantation of Sertoli cells in chemoablated mouse testis.

Conclusions

Endogenous VSELs (which survive oncotherapy) can possibly regenerate non-functional gonads in cancer survivors when exposed to a healthy niche in vitro or in vivo (by way of transplanting mesenchymal cells which secrete trophic factors required for endogenous VSELs to differentiate into gametes). Presence of VSELs can also explain spontaneous pregnancies after BMT and cortical tissue transplantation (at heterotopic or orthotopic sites). This understanding once verified and accepted by the scientific community could obviate the need to remove whole ovary or testicular biopsy for cryopreservation prior to oncotherapy.

Novel Action of FSH on Stem Cells in Adult Mammalian Ovary Induces Postnatal Oogenesis and Primordial Follicle Assembly

Adult mammalian ovary has been under the scanner for more than a decade now since it was proposed to harbor stem cells that undergo postnatal oogenesis during reproductive period like spermatogenesis in testis. Stem cells are located in the ovary surface epithelium and exist in adult and menopausal ovary as well as in ovary with premature failure. Stem cells comprise two distinct populations including spherical, very small embryonic-like stem cells (VSELs which express nuclear OCT-4 and other pluripotent and primordial germ cells specific markers) and slightly bigger ovarian germ stem cells (OGSCs with cytoplasmic OCT-4 which are equivalent to spermatogonial stem cells in the testes). These stem cells have the ability to spontaneously differentiate into oocyte-like structures in vitro and on exposure to a younger healthy niche. Bone marrow may be an alternative source of these stem cells. The stem cells express FSHR and respond to FSH by undergoing self-renewal, clonal expansion, and initiating neo-oogenesis and primordial follicle assembly. VSELs are relatively quiescent and were recently reported to survive chemotherapy and initiate oogenesis in mice when exposed to FSH. This emerging understanding and further research in the field will help evolving novel strategies to manage ovarian pathologies and also towards oncofertility.

Peritoneal carcinomatosis: A malignant disease with an embryological origin?

INTRODUCTION

In 1931, Simpson et al. coined the term "peritoneal carcinomatosis" to describe the regional spread of ovarian tumors as localized or extended with involvement of the peritoneal serous membrane and neighboring anatomical structures. Research into the origin of peritoneal carcinomatosis is based on two phases in a woman's life: EMBRYO DEVELOPMENT: During week 3, the bilaminar disc becomes a trilaminar disc called the mesoderm. Inside the lateral plate mesoderm, the coelomic cavity is divided into 2 layers: the parietal (somatic) mesoderm, which gives rise to the parietal peritoneum and pleural surfaces; and the visceral (splanchnic) mesoderm, which gives rise to the visceral peritoneum, visceral surface of the pleura, gonadal stroma, and the muscular layer of the hollow viscera and its mesenteries.

TUMOR SPREAD

Transcoelomic metastasis and metaplasia of pluripotent stem cells in the peritoneum was involved in the pathogenesis of ovarian cancer. This involvement takes the form of a synchronous malignant transformation at multiple foci and may cause intraperitoneal field cancerization. Pluripotent stem cells play a role both in the development of the embryonic peritoneum and in the spread of transcoelomic tumors. Consequently, knowledge of the origin of these cells (embryonic or current) could be extremely useful. The many markers that act during the embryonic period can affect descendants, that is, cells are already marked before specification and differentiation are activated. Thus, programmed activation could be attributed to genetic and epigenetic changes.

Exploratory study of pre-surgical medications with dienogest or leuprorelin in laparoscopic cystectomy of endometrial cysts

AIM

The aim of this study was to compare the effects of pre-surgical medication with dienogest or leuprorelin on post-surgical ovarian function.

MATERIAL AND METHODS

We conducted an exploratory study in two centers in Japan that comprised 30 patients with ovarian endometrial cysts for whom surgical excision was planned. Patients were enrolled and divided into pre-surgical medication groups with dienogest or leuprorelin for 12 weeks. Thereafter, patients were treated by laparoscopic cystectomy. The primary outcome was ovarian function post-surgery, as assessed by serum anti-Müllerian hormone (AMH) level, antral follicle count (AFC) and resumption of menses. Secondary outcome was the effect of pre-surgical medication, as assessed by the size of endometrial cysts and visual analog scale (VAS) score. Serum AMH, AFC, size of endometrial cysts, and VAS scores were measured at baseline (before medication), after medication (1 day before surgery), and at 4 and 12 weeks post-surgery.

RESULTS

Serum AMH levels did not change after pre-surgical medication with either dienogest or leuprorelin. Although AMH decreased after surgery, it recovered by 12 weeks post-surgery in both groups with no statistically significant difference. Mean AFC did not change after surgery in either group. Menses returned by 12 weeks post-surgery in all patients except for those who were pregnant. The rate of reduction of endometrial cyst volume did not differ between the groups. Both dienogest and leuprorelin were associated with substantial reductions in VAS scores.

CONCLUSION

There were no statistically significant differences between pre-surgical medication with dienogest and leuprorelin in post-surgical ovarian function. Both medications were effective in reducing endometrial cyst volume and VAS score.

Mouse Ovarian Very Small Embryonic-Like Stem Cells Resist Chemotherapy and Retain Ability to Initiate Oocyte-Specific Differentiation

This study was undertaken to investigate stem cells in adult mouse ovary, the effect of chemotherapy on them and their potential to differentiate into germ cells. Very small embryonic-like stem cells (VSELs) that were SCA-1+/Lin-/CD45-, positive for nuclear octamer-binding transforming factor 4 (OCT-4), Nanog, and cell surface stage-specific embryonic antigen 1, were identified in adult mouse ovary. Chemotherapy resulted in complete loss of follicular reserve and cytoplasmic OCT-4 positive progenitors (ovarian germ stem cells) but VSELs survived. In ovarian surface epithelial (OSE) cell cultures from chemoablated ovary, proliferating germ cell clusters and mouse vasa homolog/growth differentiation factor 9-positive oocyte-like structure were observed by day 6, probably arising as a result of differentiation of the surviving VSELs. Follicle-stimulating hormone (FSH) exerted a direct stimulatory action on the OSE and induced stem cells proliferation and differentiation into premeiotic germ cell clusters during intact chemoablated ovaries culture. The FSH analog pregnant mare serum gonadotropin treatment to chemoablated mice increased the percentage of surviving VSELs in ovary. The results of this study provide evidence for the presence of potential VSELs in mouse ovaries and show that they survive chemotherapy, are modulated by FSH, and retain the ability to undergo oocyte-specific differentiation. These results show relevance to women who undergo premature ovarian failure because of oncotherapy.

Novel methods of treating ovarian infertility in older and POF women, testicular infertility, and other human functional diseases

In vitro maturation (IVM) and in vitro fertilization (IVF) technologies are facing with growing demands of older women to conceive. Although ovarian stem cells (OSCs) of older women are capable of producing in vitro fresh oocyte-like cells (OLCs), such cells cannot respond to IVM and IVF due to the lack of granulosa cells required for their maturation. Follicular renewal is also dependent on support of circulating blood mononuclear cells. They induce intermediary stages of meiosis (metaphase I chromosomal duplication and crossover, anaphase, telophase, and cytokinesis) in newly emerging ovarian germ cells, as for the first time demonstrated here, induce formation of granulosa cells, and stimulate follicular growth and development. A pretreatment of OSC culture with mononuclear cells collected from blood of a young healthy fertile woman may cause differentiation of bipotential OSCs into both developing germ and granulosa cells. A small blood volume replacement may enable treatment of ovarian infertility in vivo. The transferred mononuclear cells may temporarily rejuvenate virtually all tissues, including improvement of the function of endocrine tissues. Formation of new follicles and their development may be sufficient for IVM and IVF. The novel proposed in vitro approaches may be used as a second possibility. Infertility of human males affects almost a half of the infertility cases worldwide. Small blood volume replacement from young healthy fertile men may also be easy approach for the improvement of sperm quality in older or other affected men. In addition, body rejuvenation by small blood volume replacement from young healthy individuals of the same sex could represent a decline of in vitro methodology in favor of in vivo treatment for human functional diseases. Here we propose for the first time that blood mononuclear cells are essential for rejuvenation of those tissues, where immune system components participate in an appropriate division and differentiation of tissue stem cells. If needed, small blood volume replacement from distinct young healthy individuals could be utilized in six month intervals for repair of young altered or aged reproductive and other tissue functions. Systemic and local use of honey bee propolis tincture is an alternative option for functional rejuvenation of some tissues.

Identification and characterization of epithelial cells derived from human ovarian follicular fluid

Introduction

Follicular fluid is important for follicular development and oocyte maturation. Evidence suggests that follicular fluid is not only rich in proteins but cells. Besides oocytes, the follicular fluid contains granulosa, thecal, and ovarian surface epithelial cells, and both granulosa and thecal cells are well-characterized. However, epithelial cells in follicular fluid are poorly studied. This study aims to isolate and characterize in vitro epithelial cells that originate from human ovarian follicular fluid retrieved in the assisted fertilization program.

Methods

Follicular fluid samples were collected from 20 women in the assisted reproduction program. Epithelial cells were characterized by flow cytometry assay, immunofluorescence staining, real-time PCR, and time lapse photography.

Results

Epithelial cell cultures were established from 18 samples. A small population of epithelial cells expresses germ-line stem cell markers, such as octamer-binding transcription factor 4 (OCT4), NANOG, and DEAD box polypeptide 4 (DDX4). In the epithelial cell culture system, oocyte-like cells formed spontaneously in vitro and expressed the following transcription markers: deleted in azoospermia-like (DAZL), developmental pluripotency associated protein 3 stella-related protein (STELLA), zona pellucida gene family C (ZPC), Syntaptonemal complex protein (SCP), and growth and differentiation factor 9 (GDF9). Some of the oocyte-like cells developed a zona pellucida-like structure. Both the symmetric and asymmetric division split of epithelial cells and early developing oocytes were observed using time lapse photography. Cell colonies were formed during epithelial culturing, which maintained and proliferated in an undifferentiated way on the feeder layer and expressed some pluripotency markers. These colonies differentiated in vitro into various somatic cell types in all three germ layers, but did not form teratoma when injected into immunodeficient mice. Furthermore, these epithelial cells could be differentiated directly to functional hepatocyte-like cells, which do not exist in ovarian tissues.

Conclusions

The epithelial cells derived from follicular fluid are a potential stem cell source with a pluripotent/multipotent character for safe application in oogenesis and regenerative medicine.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0004-6) contains supplementary material, which is available to authorized users.

Stem cells, progenitor cells, and lineage decisions in the ovary

Exploring stem cells in the mammalian ovary has unleashed a Pandora's box of new insights and questions. Recent evidence supports the existence of stem cells of a number of the different cell types within the ovary. The evidence for a stem cell model producing mural granulosa cells and cumulus cells is strong, despite a limited number of reports. The recent identification of a precursor granulosa cell, the gonadal ridge epithelial-like cell, is exciting and novel. The identification of female germline (oogonial) stem cells is still very new and is currently limited to just a few species. Their origins and physiological roles, if any, are unknown, and their potential to produce oocytes and contribute to follicle formation in vivo lacks robust evidence. The precursor of thecal cells remains elusive, and more compelling data are needed. Similarly, claims of very small embryonic-like cells are also preliminary. Surface epithelial cells originating from gonadal ridge epithelial-like cells and from the mesonephric epithelium at the hilum of the ovary have also been proposed. Another important issue is the role of the stroma in guiding the formation of the ovary, ovigerous cords, follicles, and surface epithelium. Immune cells may also play key roles in developmental patterning, given their critical roles in corpora lutea formation and regression. Thus, while the cellular biology of the ovary is extremely important for its major endocrine and fertility roles, there is much still to be discovered. This review draws together the current evidence and perspectives on this topic.

The impact of mitochondrial function/dysfunction on IVF and new treatment possibilities for infertility

Mitochondria play vital roles in oocyte functions and they are critical indicators of oocyte quality which is important for fertilization and development into viable offspring. Quality-compromised oocytes are correlated with infertility, developmental disorders, reduced blastocyst cell number and embryo loss in which mitochondrial dysfunctions play a significant role. Increasingly, women affected by metabolic disorders such as diabetes or obesity and oocyte aging are seeking treatment in IVF clinics to overcome the effects of adverse metabolic conditions on mitochondrial functions and new treatments have become available to restore oocyte quality. The past decade has seen enormous advances in potential therapies to restore oocyte quality and includes dietary components and transfer of mitochondria from cells with mitochondrial integrity into mitochondria-impaired oocytes. New technologies have opened up new possibilities for therapeutic advances which will increase the success rates for IVF of oocytes from women with compromised oocyte quality.

In-vitro culture system for mesenchymal progenitor cells derived from waste human ovarian follicular fluid

To characterize different cell populations in the human ovary, morphological and functional characteristics of cell populations collected during routine IVF procedures were studied. Cells obtained from follicular fluid grew in vitro under minimal medium conditions, without growth factor, including leukaemia-inhibiting factor. Morphological analysis revealed a heterogeneous cell population, with cells displaying a fibroblast-like, epithelial-like and also neuron-like features. Morpho-functional characteristics of fibroblast-like cells were similar to mesenchymal stem cells, and, in particular, were positive for mesenchymal stemness markers, including CD90, CD44, CD105, CD73, but negative for epithelial proteins, such as cytokeratins, CD34 and CD45 antigens. Cell proliferation activity at different times and colony-forming unit capability were evaluated, and multipotency of a subset of granulosa cells was established by in-vitro differentiation studies (e.g. osteogenic, chondrogenic and adipogenic differentiation). This study suggests that cells provided by mesenchymal plasticity can be easily isolated by waste follicular fluid, avoiding scraping of human ovaries, and cultivated in minimal conditions. Successful growth of such progenitor cells on three-dimensional cryogel scaffold provides the basis for future developments in tissue engineering. This culture system may be regarded as an experimental model in which biological behaviour is not influenced by specific growth factors.

Ovarian adult stem cells: hope or pitfall?

For many years, ovarian biology has been based on the dogma that oocytes reserve in female mammals included a finite number, established before or at birth and it is determined by the number and quality of primordial follicles developed during the neonatal period. The restricted supply of oocytes in adult female mammals has been disputed in recent years by supporters of postnatal neo-oogenesis. Recent experimental data showed that ovarian surface epithelium and cortical tissue from both mouse and human were proved to contain very low proportion of cells able to propagate themselves, but also to generate immature oocytes in vitro or in vivo, when transplanted into immunodeficient mice ovaries. By mentioning several landmarks of ovarian stem cell reserve and addressing the exciting perspective of translation into clinical practice as treatment for infertility pathologies, the purpose of this article is to review the knowledge about adult mammalian ovarian stem cells, a topic that, since the first approach quickly attracted the attention of both the scientific media and patients.

Post-natal oogenesis: a concept for controversy that intensified during the last decade

For decades, scientists have considered that female mammals are born with a lifetime reserve of oocytes in the ovary, irrevocably fated to decline after birth. However, controversy in the matter of the possible presence of oocytes and granulosa cells that originate from stem cells in the adult mammalian ovaries has been expanded. The restricted supply of oocytes in adult female mammals has been disputed in recent years by supporters of neo-oogenesis, who claim that germline stem cells (GSCs) exist in the ovarian surface epithelium (OSE) or the bone marrow (BM). Differentiation of ovarian stem cells (OSCs) into oocytes, fibroblast-like cells, granulosa phenotype, neural and mesenchymal type cells and generation of germ cells from OSCs under the contribution of an OSC niche that consists of immune system-related cells and hormonal signalling has been claimed. Although these arguments have met with intense suspicion, their confirmation would necessitate the revision of the current classic knowledge of female reproductive biology.

Stem cells and the reproductive system: historical perspective and future directions

Recent findings in stem cell biology have presented new perspectives and opportunities for the treatment of reproductive disease. In a departure from the long held dogma of embryologically fixed numbers of oocytes, current literature suggests that human ovaries contain stem cells which form new oocytes even in adulthood and that these stem cells can be cultured in vitro to develop into mature oocytes. These findings have provided new hope and broader options for fertility preservation. Evidence of endometrial regeneration by bone marrow stem cells in endometrial tissue of women who received bone marrow transplant highlight potential for the novel treatments of uterine disorders and supports new theories for the etiology of endometriosis - ectopic transdifferentiation of stem cells. Further, endometrial derived stem cells have been demonstrated to be useful in the treatment of several chronic and often debilitating diseases, including Parkinson's Disease and Diabetes. Other cells that may present future therapeutic benefits for a myriad of disease states include placental and fetal cells which enter maternal circulation during pregnancy and can later promote parenchymal regeneration in maternal tissue. These findings highlight novel functions of the uterus and ovaries. They demonstrate that the uterus is a dynamic organ permeable to fetal stem cells capable of transdifferentiation as well as a renewable source of multipotent stem cells. While we still have much to understand about stem cells, their potential applications in reproductive biology and medicine are countless.

Contrasting selected reproductive challenges of today with those of antiquity--the past is prologue

Viewing human history through a medical lens provides a renewed appreciation for today's vexing reproductive challenges, as some modern dilemmas are actually continuations of similar challenges experienced long ago. Certainly there are many examples of assisted fertility therapy that were entirely theoretical only a generation ago, but have become commonplace in modern practice and society. In particular posthumous birth and infertility have, over time, been the focus of compelling social interest, occasionally even impacting national security and dynastic succession. While the concepts have remained static, the tools available to extend and improve reproductive success have changed radically. Appropriately regarded as confidential and private, an individual's reproductive details are typically impervious to formal study. Yet, archival sources including ancient literature and formal court records can occasionally provide evidence of otherwise deeply personal concerns of a different era. Our assessment finds the issues, worries, and desires of patients of antiquity to align closely with contemporary reproductive challenges. Because children and family have always been central to the human experience, the consequences of reproduction (or the lack thereof) can make substantial imprints upon the cultural, economic, and political landscape-irrespective of civilization or century. In this article, selected motifs are described in a broad historical context to illustrate how challenges of human reproduction have remained essentially unchanged, despite a vast accumulation of knowledge made possible by gains in reproductive science and technology. Plus ça change, plus c'est la même chose. -Jean-Baptiste Alphonse Karr (1808-1890).

Location and characterization of female germline stem cells (FGSCs) in juvenile porcine ovary

OBJECTIVES

Existence of germline stem cells (GSCs) in juvenile mammalian female ovaries has been drastically debated recently since reports that adult mouse ovaries still have mitotically active germ cells have been proposed. In addition, definitive location of such female germline stem cells (FGSCs) had not been demonstrated.

MATERIALS AND METHODS

We segregated porcine FGSCs mechanically from ovary cortex, and tested our hypotheses by utilizing immunofluorescent staining, qRT-PCR and western blotting.

RESULTS

We attached emphasis to unambiguous location of FGSCs, which settle simultaneously in the theca. Dissected cells from porcine thecal layers maintained similar characteristics to mouse FGSCs and ESCs over 4-months in vitro culture.

CONCLUSION

These results may provide a new resource for the study of oogenesis and therapy for ovarian sterility.