Angiogenesis in ovarian follicular and luteal development

Semaphorin 3E-Plexin-D1 Pathway Downstream of the Luteinizing Hormone Surge Regulates Ovulation, Granulosa Cell Luteinization, and Ovarian Angiogenesis in Mice

Ovulation is induced by the luteinizing hormone (LH) surge and accompanied by granulosa cell luteinization and ovarian angiogenesis. Semaphorin 3E (Sema3E)-Plexin-D1 pathway regulates angiogenesis in other tissues, but its role in the ovary is unknown. Evidence indicates that Sema3E-Plexin-D1 pathway plays an important role in the mouse ovary. The expression of Sema3E and its receptor, Plexin-D1, is dynamically regulated in the mouse ovary downstream of the LH surge. This regulation requires the modulation of chromatin accessibility by CCAAT/enhancer-binding proteins α and β. Intraovarian injection of recombinant Sema3E results in reduced ovulation, impaired corpus luteum formation, and aberrant ovarian angiogenesis. These in vivo physiological abnormalities are consistent with altered expression of genes regulating these processes, and with data from in vitro cultured granulosa cells and ovarian stromal tissues treated with Sema3E or neutralizing antibody of Plexin-D1. The findings pinpoint Sema3E-Plexin-D1 pathway as a potential therapeutic target for fertility and infertility management.

Primordial Follicle Survival and Changes in Ovarian Vasculature May Be Independently Regulated During Chemotherapy

Chemotherapeutic agents induce irreversible gonadotoxic side effects, resulting in endocrine dysfunction and infertility in female cancer survivors. In the current study, we investigated strategies to protect ovarian function from chemotherapy-induced toxicity by evaluating the effects of cisplatin, doxorubicin, or cyclophosphamide on ovarian vasculature and primordial follicle survival. This investigation was conducted using adult CD-1, PDs 5-7 CD-1, and oocyte-specific Trp63 conditional knockout (Trp63 cKO) mice that demonstrated primordial follicles survived following chemotherapy. In control ovaries, vasculature typically surrounds primordial and primary follicles, is in the theca layer as secondary follicles develop, and is distributed among stromal cells. Our findings revealed that the expression pattern of CD31/PECAM-1 (platelet endothelial adhesion molecule-1) was significantly altered in ovaries treated with chemotherapeutic agents compared with controls. The data demonstrate that these agents not only caused the loss of ovarian follicles but also damaged the ovarian vasculature. Using Trp63 cKO mice and CK2II, an inhibitor of checkpoint kinase 2, we demonstrated that vascular damage can occur independently of primordial follicle loss, and VEGFA165 was unable to prevent either outcome. This indicates that the mechanisms governing the death of primordial follicles and vascular damage may not directly affect each other. Long-term ex vivo culture and in vivo experiments demonstrated the ability of ovarian vasculature to recover from cisplatin-induced damage. In conclusion, our study suggests that ovarian follicle survival and vascular integrity may be independently regulated as independent processes, governed by distinct signaling pathway or mechanisms.

Beneficial effects of apigenin on ovarian histological changes and angiogenesis gene expression in rat model of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common heterogeneous reproductive disorder and can affect approximately 10% of women of reproductive age. Abnormal vasculogenesis is a common event in polycystic ovary syndrome. This study planned to evaluate the antiangiogenic role of apigenin in ovarian histology, gene expression, and vascular density and stability in an experimental model of PCOS. Twenty-eight rats weighing 180-250 g were divided into 4 groups. Seven rats in the control group remain intact and without treatment. In 21 rats, an ovary polycystic model with a single injection of estradiol valerate was established. The PCOS rats were treated with vehicle, apigenin 10, or apigenin 20 mg/kg in three different PCOS groups for 14 days. At the end, a histological assessment of the ovaries was performed to determine collagen density and follicle counting. The endothelial or periendothelial cells were determined by immunohistochemical assay, and angiogenesis gene expression was determined using molecular assessments. Apigenin treatment partially restored follicular development, decreased the number of cysts, and increased corpora lutea in PCOS rats. Also, apigenin decreased the collagen density in the polycystic ovaries. However, apigenin administration mitigated ovarian angiogenesis by a reduction in endothelial and periendothelial cell numbers. A decrease in VEGF and VEGF R2 (kinase insert domain receptor, KDR) expressions was found after the treatment of rats with apigenin. Conclusively, our data revealed that apigenin improves ovarian histological alterations and follicular dynamics in polycystic ovary rats. The effect is partially mediated by suppression of the VEGF signaling system and reduction in endothelial and periendothelial cell proliferation.

Proteomics profiling reveals lipid metabolism abnormalities during oogenesis in unexplained recurrent pregnancy loss

Background

Unexplained recurrent pregnancy loss (URPL) is a clinical dilemma in reproductive fields. Its diagnosis is mainly exclusionary after extensive clinical examination, and some of the patients may still face the risk of miscarriage.

Methods

We analyzed follicular fluid (FF) from in vitro fertilization (IVF) in eight patients with URPL without endocrine abnormalities or verifiable causes of abortion and eight secondary infertility controls with no history of pregnancy loss who had experienced at least one normal pregnancy and delivery by direct data-independent acquisition (dDIA) quantitative proteomics to identify differentially expressed proteins (DEPs). In this study, bioinformatics analysis was performed using online software including g:profiler, String, and ToppGene. Cytoscape was used to construct the protein-protein interaction (PPI) network, and ELISA was used for validation.

Results

Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that the DEPs are involved in the biological processes (BP) of complement and coagulation cascades. Apolipoproteins (APOs) are key proteins in the PPI network. ELISA confirmed that APOB was low-expressed in both the FF and peripheral blood of URPL patients.

Conclusion

Dysregulation of the immune network intersecting coagulation and inflammatory response is an essential feature of URPL, and this disequilibrium exists as early as the oogenesis stage. Therefore, earlier intervention is necessary to prevent the development of URPL. Moreover, aberrant lipoprotein regulation appears to be a key factor contributing to URPL. The mechanism by which these factors are involved in the complement and coagulation cascade pathways remains to be further investigated, which also provides new candidate targets for URPL treatment.

Local effect of allopregnanolone in rat ovarian steroidogenesis, follicular and corpora lutea development

Allopregnanolone (ALLO) is a known neurosteroid and a progesterone metabolite synthesized in the ovary, CNS, PNS, adrenals and placenta. Its role in the neuroendocrine control of ovarian physiology has been studied, but its in situ ovarian effects are still largely unknown. The aims of this work were to characterize the effects of intrabursal ALLO administration on different ovarian parameters, and the probable mechanism of action. ALLO administration increased serum progesterone concentration and ovarian 3β-HSD2 while decreasing 20α-HSD mRNA expression. ALLO increased the number of atretic follicles and the number of positive TUNEL granulosa and theca cells, while decreasing positive PCNA immunostaining. On the other hand, there was an increase in corpora lutea diameter and PCNA immunostaining, whereas the count of TUNEL-positive luteal cells decreased. Ovarian angiogenesis and the immunohistochemical expression of GABAA receptor increased after ALLO treatment. To evaluate if the ovarian GABAA receptor was involved in these effects, we conducted a functional experiment with a specific antagonist, bicuculline. The administration of bicuculline restored the number of atretic follicles and the diameter of corpora lutea to normal values. These results show the actions of ALLO on the ovarian physiology of the female rat during the follicular phase, some of them through the GABAA receptor. Intrabursal ALLO administration alters several processes of the ovarian morpho-physiology of the female rat, related to fertility and oocyte quality.

Expression of genes for transport of water and angiogenesis, as well as biochemical biomarkers in Holstein dairy cows during the ovsynch program

Changes in expression of genes associated with angiogenesis and transport of water by cells, as well as biomarkers of oxidative stress were determined at specific times during the ovsynch protocol to synchronize estrus and breed Holstein dairy cows. Blood samples were taken from 82 lactating Holstein cows at the time of the 1st GnRH injection (G1), 7 days later at the time of the PGF2a (PG) injection, and 48 h after the PGF2a treatment when the second injection of GnRH was administered (G2). The serum was analyzed for malondialdehyde (MDA), reduced glutathione (GSH), glutathione peroxidase (GPX), nitric oxide (NO), catalase (CAT), and total antioxidant capacity (TAC). The expression of vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor 2 (VEGFR2), endothelial nitric oxide synthase (eNOS3), aquaporin 3 (AQP3), and AQP4 mRNAs in peripheral blood mononuclear cells (PBMCs) was analyzed. The number of copies of each of the mRNAs was quantified using qPCR. Pregnancy status was determining at 32 ± 3 days after insemination using an ultrasound "Sonoscape-5V″ model. Receiver operating curves (ROC) were used to assess the sensitivity and specificity of the biochemical parameters in serum to predict establishment of p The expression of MDA, GPX, and Catalase changed (P < 0·05) between G1, PG and G2 phases of the ovsynch protocol with higher levels at PG than at G1 and G2. The highest levels of NO were detected at G2. The ROC analyses identified NO, TAC and CAT as the most sensitive and specific biomarker for pregnancy with areas under the curve being 0.875 (P < 0.0001), 0.843 (P < 0.03), 0.833 (P < 0.017), sensitivity being 75.3, 42.86, and 26.27%, and specificity being 90, 90 and 85% respectively. The expression for VEGF, VEGFR2, eNOS3, AQP3, and AQP4 mRNAs was upregulated at PG compared to G1 and G2 phases of the ovsynch protocol. The results suggest that following the first injection of GnRH, there is an increase in expression of VEGF, VEGFR2, eNOS3, AQP3, and AQP4 mRNAs by the time of the PGF2a injection and then expression decreased. Further, ROC analyses identified increases in NO, TAC and CAT as the most sensitive and specific biomarkers with the greatest potential to predict establishment of pregnancy in Holstein cows.

Neo-vascularization-based therapeutic perspectives in advanced ovarian cancer

The process of angiogenesis is well described for its potential role in the development of normal ovaries, and physiological functions as well as in the initiation, progression, and metastasis of ovarian cancer (OC). In advanced stages of OC, cancer cells spread outside the ovary to the pelvic, abdomen, lung, or multiple secondary sites. This seriously limits the efficacy of therapeutic options contributing to fatal clinical outcomes. Notably, a variety of angiogenic effectors are produced by the tumor cells to initiate angiogenic processes leading to the development of new blood vessels, which provide essential resources for tumor survival, dissemination, and dormant micro-metastasis of tumor cells. Multiple proangiogenic effectors and their signaling axis have been discovered and functionally characterized for potential clinical utility in OC. In this review, we have provided the current updates on classical and emerging proangiogenic effectors, their signaling axis, and the immune microenvironment contributing to the pathogenesis of OC. Moreover, we have comprehensively reviewed and discussed the significance of the preclinical strategies, drug repurposing, and clinical trials targeting the angiogenic processes that hold promising perspectives for the better management of patients with OC.

Luteal Function, Biometrics, and Echotextural Attributes in Santa Inês Ewes Superovulated with Different Total Doses of Porcine Follicle-Stimulating Hormone

Premature regression of corpora lutea (PRCL) may adversely affect the outcome of hormonal ovarian superstimulation in small ruminants, and the total dose of exogenous gonadotropins used may be one of the causes of this condition. There were two major objectives of the present study: (1) to evaluate the effects of different superovulatory doses of porcine follicle-stimulating hormone (pFSH) on the biometry, blood perfusion (Doppler), and echotextural characteristics of luteal structures; and, (2) to determine the usefulness of biometric, vascular, and echotextural luteal variables, as well as measurements of circulating progesterone (P₄) concentrations for early detection of PRCL in superovulated Santa Inês ewes. Twenty-seven Santa Inês ewes received an intravaginal P₄-releasing device (CIDR) from Days 0 to 8 (Day 0 = random day of the anovulatory period). An IM injection of d-cloprostenol (37.5 μg) was given at the time of the CIDR insertion and withdrawal. On Day 6, all the ewes received 300 IU of eCG IM and were divided into three treatment groups (each n = 9): G100 (100 mg); G133 (133 mg); and G200 (200 mg of pFSH) administered IM every 12 h in eight injections. Transrectal ovarian ultrasonography and jugular blood sampling for serum P₄ measurements were performed on Days 11 to 15. On the day of embryo recovery (Day 15), all the ewes underwent diagnostic videolaparoscopy and were classified, based on their luteal characteristics, into three response groups: nCL (ewes with normal CL only); rCL (ewes with regressing CL only); and ewes with both nCL and rCL following the superovulatory regimen. Our present results indicate that the total pFSH doses of 100 mg and 200 mg result in similar ovulatory responses and luteal function/biometrics, although the percentage of donor ewes with nCL was greater (p < 0.05) for G100 compared with the G200 animals. An application of 133 mg of pFSH was associated with diminished luteogenesis. Lastly, circulating P₄ concentrations, ultrasonographic estimates of total luteal area, and CL pixel heterogeneity (standard deviation of numerical pixel values) are promising markers of luteal inadequacy in superovulated ewes.

Molecular Mediators and Regulators of Retinal Angiogenesis

BACKGROUND

Retinal neovascularization is the major cause of vision loss that affects both adults and young children including premature babies. It has been a major pathology in several retinal diseases like age-related macular degeneration (AMD), diabetic retinopathy (DR) and retinopathy of prematurity (ROP). Current treatment modalities such as anti-VEGF therapy, laser are not suitable for every patient and response to these therapies is highly variable. Thus, there is a need to investigate newer therapeutic targets for DR, ROP and AMD, based on a clear understanding of disease pathology and regulatory mechanisms involved.

METHOD

Appropriate articles published till February 2021 were extracted from PUBMED using keywords like ocular angiogenesis, DR, ROP, AMD, miRNA, mRNA, and cirMiRNA and containvaluable information regarding the involvement of miRNA in causing neovascularization. After compiling the list of miRNA regulating mRNA expression in angiogenesis and neovascularaization, their interactions were studied using online available tool MIENTURNET (http://userver.bio.uniroma1.it/apps/mienturnet/). The pathways involved in these processes were also predicted using the same tool.

RESULTS

Most of the studies have explored potential targets like HIF1-α, PDGF, TGFβ, FGF, etc., for their involvement in pathological angiogenesis in different retinal diseases. The regulatory role of microRNA (miRNA) has also been explored in various retinal ocular pathologies. This review highlights regulatory mechanism of cellular and circulatory miRNAs and their interactions with the genes involved in retinal neovascularization. The role of long noncoding RNA (ncRNA) in the regulation of genes involved in different pathways is also noteworthy and discussed in this review.

CONCLUSION

This review highlights the potential regulatory mechanism/pathways involved in retinal neovascularization and its implications in retinal diseases and for identifying new drug targets.

A single-cell transcriptomic atlas characterizes cell types and their molecular features in yak ovarian cortex

The ovary as one of the most dynamic organs produces steroids to orchestrate female secondary sexual characteristics, harbors ovarian reserve for oocytes, releases mature oocytes for fertilization, and maintains pregnancy. Yak (Bos grunniens) is the only bovid animal that can adapt to the harsh climatic conditions on the Qinghai-Tibetan Plateau (altitudes of over 3000 m above sea level). However, the cellular atlas is composed of oocytes and other somatic cells, and their individual molecular characteristics remain to be elucidated in the yak ovary. Here, single-cell RNA sequencing (scRNA-seq) was performed to delineate the molecular signature of various cell types in the yak ovarian cortex. A cellular atlas of yak ovarian cortex was constructed successfully on the basis of the differentially expressed genes (DEGs) from the distinct cell types and their functional enrichment analysis, comprising endothelial cells, nature kill cells, stromal cells, smooth muscle cells, oocytes, macrophages, epithelial cells, and granulosa cells. Meanwhile, the signature genes were determined based on their expression specificity in each cell type. A cell-to-cell communication network was built in light of the differentially overexpressed ligand and receptor genes from each cell type. Further, the oocytes were subdivided into four subtypes based on their individual DEGs and the functional enrichment of the DEGs. FST and TOP2A were identified as maker genes for oocytes by immunostaining in the yak ovarian cortex. The cellular atlas reveals the biological characteristics of the ovarian cortex at the cellular molecular level and provides insights into female reproductive biology via cellular communications in the yak.

Hormone regulation of thrombospondin-1 mRNA in porcine granulosa cells in vitro

Thrombospondin-1 (THBS1) is involved in the process of angiogenesis and is down-regulated by insulin-like growth factor 1 (IGF1) in porcine granulosa cells (GC), but what other hormones regulate GC THBS1 and its role in follicular growth is unclear. Thus, six experiments were conducted to determine the influence of other hormones on THBS1 gene expression in porcine GC, and to determine if THBS1 mRNA changes during follicular development. For Exp. 1-5, small (1-5 mm) follicles from ovaries of abattoir gilts were aspirated, GC collected and treated with FSH, IGF1, fibroblast growth factor 9 (FGF9), Sonic hedgehog (SHH), estradiol, cortisol, and/or prostaglandin E2 (PGE2). FSH, IGF1 and FGF9 each decreased (P < 0.05) THBS1 mRNA abundance. Alone, PGE2 increased (P < 0.05) THBS1 mRNA abundance. PGE2 significantly attenuated the FSH-induced inhibition of THBS1 mRNA expression. Estradiol, cortisol, and SHH had no effect on THBS1 mRNA abundance. In Exp. 6, small (1-3 mm), medium (4-6 mm) and large (7-14 mm) follicles were aspirated to measure abundance of THBS1 mRNA in GC which did not differ (P > 0.10) between small and medium-sized follicles but was threefold greater (P < 0.05) in large compared to small or medium follicles. We hypothesize that the inhibitory effects of FSH, IGF1 and FGF9 on the antiangiogenic gene THBS1 could contribute to promoting angiogenesis in the developing follicle, while stimulation of THBS1 mRNA by PGE2 may help reduce angiogenesis during the preovulatory period when PGE2 and THBS1 mRNA are at their greatest levels.

Achieving full-term pregnancy in the vizcacha relies on a reboot of luteal steroidogenesis in mid-gestation (Lagostomus maximus, Rodentia)

Reactivation of the hypothalamic-pituitary-ovarian (HPO) axis triggered by the decline in serum progesterone in mid-gestation is an uncommon trait that distinguishes the vizcacha from most mammals. Accessory corpora lutea (aCL) developed upon this event have been proposed as guarantors of the restoration of the progesterone levels necessary to mantain gestation. Therefore, the steroidogenic input of primary CL (pCL) vs aCL was evaluated before and after HPO axis-reactivation (BP and AP respectively) and in term pregnancy (TP). Nonpregnant-ovulated females (NP) were considered as the pCL-starting point group. In BP, the ovaries mainly showed pCL, whose LH receptor (LHR), StAR, 3β-HSD, 20α-HSD, and VEGF immunoexpressions were similar or lower than those of NP. In AP, luteal reactivity increased significantly compared to the previous stages, and the pool of aCL developed in this stage represented 20% of the ovarian structures, equaling the percentage of pCL. Both pCL and aCL luteal cells shared similar histological features consistent with secretory activity. Although pCL and aCL showed equivalent labeling intensity for the luteotropic markers, pCL were significantly larger than aCL. Towards TP, both showed structural disorganization and loss of secretory characteristics. No significant DNA fragmentation was detected in luteal cells throughout gestation. Our findings indicate that the LH surge derived from HPO axis-reactivation targets the pCL and boost luteal steroidogenesis and thus progesterone production. Because there are many LHR-expressing antral follicles in BP, they also respond to the LH stimuli and luteinize without extruding the oocyte. These aCL certainly contribute but it is the steroidogenic restart of the pCL that is the main force that restores progesterone levels, ensuring that gestation is carried to term. Most importantly, the results of this work propose luteal steroidogenesis reboot as a key event in the modulation of vizcacha pregnancy and depict yet another distinctive aspect of its reproductive endocrinology.

Nanoparticles Accumulate in the Female Reproductive System during Ovulation Affecting Cancer Treatment and Fertility

Throughout the female menstrual cycle, physiological changes occur that affect the biodistribution of nanoparticles within the reproductive system. We demonstrate a 2-fold increase in nanoparticle accumulation in murine ovaries and uterus during ovulation, compared to the nonovulatory stage, following intravenous administration. This biodistribution pattern had positive or negative effects when drug-loaded nanoparticles, sized 100 nm or smaller, were used to treat different cancers. For example, treating ovarian cancer with nanomedicines during mouse ovulation resulted in higher drug accumulation in the ovaries, improving therapeutic efficacy. Conversely, treating breast cancer during ovulation, led to reduced therapeutic efficacy, due to enhanced nanoparticle accumulation in the reproductive system rather than at the tumor site. Moreover, chemotherapeutic nanoparticles administered during ovulation increased ovarian toxicity and decreased fertility compared to the free drug. The menstrual cycle should be accounted for when designing and implementing nanomedicines for females.

NDRG1 is expressed in human granulosa cells: An implicative role of NDRG1 in the ovary

Purpose

N-myc downstream-regulated gene 1 (NDRG1) is expressed in various human tissues and plays a role in regulating cellular proliferation, angiogenesis, and hypoxia sensing. However, the role of NDRG1 in the ovary remains poorly understood. Therefore, we investigated NDRG1 expression and the role of NDRG1 in the human ovary.

Methods

Follicular fluid (FF) and luteinized granulosa cells were collected from follicles during oocyte retrieval. KGN cells were cultured with cobalt chloride (CoCl2, a hypoxia-mimicking agent) and/or echinomycin. mRNA, protein levels and secretion, and localization were assessed by real-time PCR, Western blotting, ELISA, and immunohistochemical analysis, respectively. KGN cells were also transfected with NDRG1 siRNA for 72 h.

Results

NDRG1 protein was expressed in luteinized granulosa cells. NDRG1 concentration was positively correlated with vascular endothelial growth factor (VEGF) and progesterone concentrations in FF. CoCl2-induced hypoxic stress significantly increased NDRG1 and VEGF mRNA and protein and hypoxia-inducible factor-1α expression compared with those in the controls. The CoCl2-induced overexpression of NDRG1 and VEGF was suppressed by echinomycin. Transfection with NDRG1 siRNA significantly suppressed the release of progesterone in the culture medium.

Conclusions

These results indicate that ovarian NDRG1 may play important roles in follicular development, especially in the early luteinization of pre-ovulatory follicles.

Expression profile of the Kisspeptin/Kiss1r system and angiogenic and immunological mediators in the ovary of cyclic and pregnant cats

The Kisspeptin/Kiss1r system has been studied in mammalian ovaries. However, there are still no studies on the modulation of this system and its relationship with angiogenic and immunological mediators in the ovary of domestic cats, especially during pregnancy. We evaluated the expression of Kisspeptin/Kiss1r and angiogenic and immunological mediators during folliculogenesis, luteogenesis and luteal regression of cyclic and pregnant cats. The ovary exhibited moderate to intense expression for Kiss1, VEGF, Flk-1, INFγ and MIF in oocytes and the follicular wall, while Kiss1r expression was low in granulosa cells. In these cells, there was also a greater expression of Kiss1, INFγ and MIF, mainly in secondary follicles, while tertiary and preovulatory follicles exhibited greater expression of VEGF and Flk-1 in this layer. In luteogenesis, Kiss1 immunostaining was higher in mature corpora lutea (MCL) of pregnant cats compared to vacuolated CL (VCL) and corpus albicans (CA). Pregnancy also increased the luteal gene expression of Kiss1 as well as Kiss1, Kiss1r, Flk-1, and MIF immunostaining in MCL, while reduced the area of VEGF expression in VCL and luteal mRNA expression of Mif when compared to non-pregnant animals. In addition, positive gene correlation between Kiss1r and Mif was observed in the CL. Kiss1, Kiss1r, Vegf and Mif expression were lower in the CA of cats in anestrus. These findings reveal that the expression of Kisspeptin/Kiss1r and angiogenic and immunological mediators, in the ovary of domestic cats, depend on the follicular and luteal stage, and the luteal expression of these mediators is influenced by pregnancy.

Hypoxia: Role of SIRT1 and the protective effect of resveratrol in ovarian function

Background

Ovarian function is closely related to the degree of vascular network development surrounding the ovary. Maternal aging‐related construction defects in this vascular network can cause ovarian hypoxia, which impedes oocyte nutrient supply, leading to physiological changes in the ovaries and oocytes. The anti‐aging gene Sirtuin 1 (SIRT1) senses and adapts to ambient stress and is associated with hypoxic environments and mitochondrial biogenesis.

Methods

The present study is a literature review focusing on investigations involving the changes in SIRT1 and mitochondrial expression during hypoxia and the cytoprotective effects of the SIRT1 activator, resveratrol.

Main findings

Hypoxia suppresses SIRT1 and mitochondrial expression. Resveratrol can reverse the hypoxia‐induced decrease in mitochondrial and SIRT1 activity. Resveratrol suppresses the production of hypoxia‐inducible factor‐1α and vascular endothelial growth factor proteins.

Conclusion

Resveratrol exhibits protective activity against hypoxic stress and may prevent hypoxia‐ or aging‐related mitochondrial dysfunction. Resveratrol treatment may be a potential option for infertility therapy.

Si-Wu-Tang facilitates ovarian function through improving ovarian microenvironment and angiogenesis in a mouse model of premature ovarian failure

ETHNOPHARMACOLOGICAL RELEVANCE

Premature ovarian failure (POF) is a severe illness, characterized by premature menopause with a markedly decrease in ovarian function, which leads to infertility. Si-Wu-Tang (SWT), also called "the first prescription of gynecology" by medical experts in China, is widely used as the basic formula in regulating the menstrual cycle and treating infertility. However, the potential effect and underlying mechanisms of action of SWT on the treatment of POF have not yet been elucidated.

PURPOSE

This study aimed to explore the therapeutic effect and underlying molecular mechanism of action of SWT on the treatment of POF in C57BL/6 mice.

MATERIALS AND METHODS

The main compounds of SWT were identified by high-performance liquid chromatography (HPLC). POF model groups were established by a single intraperitoneal injection of cyclophosphamide (Cy, 100 mg/kg). SWT or dehydroepiandrosterone (DHEA) were administered via oral gavage for 28 consecutive days. Ovarian function and pathological changes were evaluated by hormone levels, follicular development, and changes in angiogenesis. Furthermore, statistical analyses of fertility were also performed.

RESULTS

Treatment with SWT significantly improved estrogen levels, the number of follicles, antioxidant defense, and microvascular formation in POF mice. Moreover, SWT significantly activated the Nrf2/HO-1 and STAT3/HIF-1α/VEGF signaling pathways to promote angiogenesis, resulting in a better fertility outcome when compared to the model group.

CONCLUSIONS

Our findings indicated that SWT protected ovarian function of Cy-induced POF mice by improving the antioxidant ability and promoting ovarian angiogenesis, thereby providing scientific evidence for the treatment of POF using SWT.

Alteration in angiogenic potential of granulosa-lutein cells and follicular fluid contributes to luteal defects in polycystic ovary syndrome

STUDY QUESTION

Is angiogenic potential of follicular fluid (FF) and granulosa-lutein cells (GLCs) altered in polycystic ovary syndrome (PCOS) and does it play a role in corpus luteum (CL) defect observed in them?

SUMMARY ANSWER

FF and GLCs of women with PCOS show reduced expression of pro-angiogenic factors compared to controls and exhibit a diminished capacity to induce angiogenesis.

WHAT IS KNOWN ALREADY

In women with PCOS, CL insufficiency and frequent miscarriage are reported, which may be due to defect in CL. The development of new blood vessels is essential to promote ovarian folliculogenesis and functional CL formation. The vasculature formation in CL which is important for its function is still unexplored in these women.

STUDY DESIGN, SIZE, DURATION

This case-control study was conducted in 30 healthy control women and 30 women with PCOS undergoing controlled ovarian hyperstimulation for IVF. The FF, GLCs and serum were collected from all participants during ovum pick up.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The capacity of FF to induce angiogenesis was assessed by measuring levels of pro-angiogenic factors vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF2) and its tube formation and wound healing potential using human umbilical vein endothelial cells (HUVECs). We investigated the angiogenic potential and endothelial cell-like nature of GLCs using several approaches such as the expression of angiogenic genes by quantitative PCR, DiI-conjugated acetylated low-density lipoproteins (Dil-Ac-LDL) internalization assay, tube formation assay, expression of endothelial cell markers by immunofluorescence analysis. In addition, correlation of transcript levels of angiogenic genes with oocyte parameters was studied.

MAIN RESULTS AND THE ROLE OF CHANCE

FF and serum levels of VEGF and FGF2 were significantly higher and lower, respectively, in PCOS compared to controls. The tube formation and wound healing capacity of HUVECs was found to be reduced when measured after supplementation with FF of women with PCOS compared to controls. This suggests a decreased angiogenic capacity of FF in women with PCOS. Tube formation (P = 0.003) and Dil-Ac-LDL internalization (P = 0.03) ability of GLCs were significantly reduced in women with PCOS compared to controls. Protein expression levels of endothelial markers, vascular endothelial growth factor A (VEGFA) (P = 0.004), vascular endothelial growth factor receptor 2 (VEGFR2) (P = 0.011), TEK Receptor Tyrosine Kinase (Tie-2) (P = 0.026), fibroblast growth factor receptor 1 (FGFR1) (P = 0.026) and CD31 (P = 0.035) and transcript levels of angiogenic genes VEGFA (P = 0.042), hypoxia inducing factor 1A (HIF1A) (P = 0.025), FGF2 (P = 0.038), angiopoietin 1 (ANGPT1) (P = 0.028), heparin sulfate proteoglycan 2 (HSPG2) (P = 0.016), ADAM metallopeptidase with thrombospondin type1 motif, 1 (ADAMTS1) (P = 0.027) and fibronectin 1 (FN1) (P = 0.016) were found to be low in GLCs of PCOS compared to controls. Thus, the findings of this study indicate that endothelial cell-like characteristics of GLCs were significantly decreased in PCOS. Furthermore, transcript levels of VEGFA (r = 0.46, P = 0.009), ADAMTS1 (r = 0.55, P = 0.001), FGF2 (r = 0.42, P = 0.022) and ANGPT2 (r = 0.47, P = 0.008) showed a positive correlation with oocyte fertilization rate.

LIMITATIONS, REASONS FOR CAUTION

The vasculature formation in CL is not possible to study in women, but we explored the angiogenic characteristics of FF and GLC obtained from women with PCOS to speculate any vascularization defect of CL in these women. The FF and GLCs were obtained from the stimulated cycle during oocyte retrieval, which may not exactly mimic the in-vivo condition. The small sample size is another limitation of this study. Larger sample size and support by color Doppler studies on CL blood flow would help to strengthen our findings.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings suggest that the altered angiogenic potential of FF and GLCs may affect vasculature development required for CL formation and function in PCOS. These findings pave the way to devise therapeutic strategies to support angiogenesis process in follicle of women with PCOS, which may improve CL insufficiency, progesterone levels and prevent frequent miscarriages in these women. Furthermore, our study also hypothesizes that the vascularization around the ovarian follicles is also compromised which may lead to the growth arrest of the follicles in PCOS, however, this needs thorough investigations.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by Grant BT/PR16524/MED/97/346/2016 from the Department of Biotechnology, Government of India. The authors have no conflicts of interest to disclose.

TRIAL REGISTRATION NUMBER

N/A.

A Narrative Review of Current Understanding of the Pathophysiology of Polycystic Ovary Syndrome: Focus on Plausible Relevance of Vitamin D

Polycystic ovarian syndrome (PCOS) is the most prevalent endocrinopathy of reproductive years. Salient features in presentation of patients PCOS include menstrual dysfunction, hyperandrogenism and/or polycystic appearance of ovaries on ultrasound. While the diagnosis of PCOS depends on presence of specified criteria, misdiagnoses are common. Despite years of extensive research, the exact aetiology of PCOS remains largely unknown. In the past decade, apart from insulin resistance and hyperandrogenemia, anti-mullerian hormone (AMH), an important marker of ovarian reserve, and vascular endothelial growth factor (VEGF), a crucial factor in angiogenesis, have been examined as plausible players of causative relevance for PCOS. Vitamin D, a sex-steroid hormone that is universally known for its relevance for skeletal health, has received increasing attention due to growing evidence supporting its pivotal in reproductive physiology and in PCOS. In this review we summarize our current understanding of the mechanisms relevant to the pathophysiology of PCOS and examine the role of vitamin D signalling in this context.

Characterizing Endocrine Status, Tumor Hypoxia and Immunogenicity for Therapy Success in Epithelial Ovarian Cancer

Epithelial ovarian cancer is predominantly diagnosed at advanced stages which creates significant therapeutic challenges. As a result, the 5-year survival rate is low. Within ovarian cancer, significant tumor heterogeneity exists, and the tumor microenvironment is diverse. Tumor heterogeneity leads to diversity in therapy response within the tumor, which can lead to resistance or recurrence. Advancements in therapy development and tumor profiling have initiated a shift from a "one-size-fits-all" approach towards precision patient-based therapies. Here, we review aspects of ovarian tumor heterogeneity that facilitate tumorigenesis and contribute to treatment failure. These tumor characteristics should be considered when designing novel therapies or characterizing mechanisms of treatment resistance. Individual patients vary considerably in terms of age, fertility and contraceptive use which innately affects the endocrine milieu in the ovary. Similarly, individual tumors differ significantly in their immune profile, which can impact the efficacy of immunotherapies. Tumor size, presence of malignant ascites and vascular density further alters the tumor microenvironment, creating areas of significant hypoxia that is notorious for increasing tumorigenesis, resistance to standard of care therapies and promoting stemness and metastases. We further expand on strategies aimed at improving oxygenation status in tumors to dampen downstream effects of hypoxia and set the stage for better response to therapy.

Evaluation of vascularization in the walls of preovulatory follicles in mares with endometritis

Endometritis is a major cause of infertility in mares. The aim of this study is to evaluate the preovulatory follicle (POF) vascularization (A mix, A red, A blue), POF diameter, POF wall thickness, and uterine diameters in mares with or without endometritis. Ten healthy mares and 10 mares with endometritis diagnosed by the combination of transrectal palpation, ultrasonographic examination, and cytology brush were enrolled in the study. Data of the groups obtained at 2 days before the ovulation (day -2) were compared with Student's t-test. Correlations of the parameters were determined by the Pearson correlation test. To the best of our knowledge, this is the first report indicating a lower vascularization of A mix, A red, A blue, and a significantly lower wall thickness in the POFs of the mares with endometritis compared to the healthy ones (p < 0.01, p < 0.05, p = 0.06, and p < 0.001, respectively). Also, a striking and novel inverse correlation between POF wall thickness and uterine diameter (r = -0.785, p < 0.001) and moderate correlations between POF wall thickness and POF vascularizations of A mix and A red (r = 0.436, p = 0.055, and r = 0.427, p = 0.060, respectively) were determined.

Resistance to Anti-angiogenic Therapies: A Mechanism Depending on the Time of Exposure to the Drugs

Angiogenesis, the formation of new blood vessels from preexisting one, represents a critical process for oxygen and nutrient supply to proliferating cells, therefore promoting tumor growth and metastasis. The Vascular Endothelial Growth Factor (VEGF) pathway is one of the key mediators of angiogenesis in cancer. Therefore, several therapies including monoclonal antibodies or tyrosine kinase inhibitors target this axis. Although preclinical studies demonstrated strong antitumor activity, clinical studies were disappointing. Antiangiogenic drugs, used to treat metastatic patients suffering of different types of cancers, prolonged survival to different extents but are not curative. In this review, we focused on different mechanisms involved in resistance to antiangiogenic therapies from early stage resistance involving mainly tumor cells to late stages related to the adaptation of the microenvironment.

Luteal blood flow as a predictive factor for methotrexate treatment outcomes in women with unruptured tubal pregnancy

BACKGROUND

Blood flow in the corpus luteum is associated with luteal function. However, the impact of luteal blood flow on methotrexate (MTX) treatment in women with unruptured tubal pregnancy has not been reported. The aim of the present study was to observe the impact of luteal blood flow on the therapeutic effect of MTX in women with unruptured tubal pregnancy.

METHODS

A prospective observational study recruited 129 women with unruptured tubal pregnancy in the First Affiliated Hospital of Xi'an Jiaotong University from September 2016 to June 2018. One hundred and fifteen women were treated successfully with MTX, and women were divided into 2 groups according to luteal blood flow: the poor luteal blood flow group and the abundant luteal blood flow group. The therapeutic effects were compared between the two groups.

RESULTS

Women in the abundant luteal blood flow group had a significantly higher serum β-human chorionic gonadotropin (β-hCG) level 4 days, 1 week and 2 weeks after MTX treatment compared with women in the poor luteal blood flow group (P < 0.05). The average diameter of the ectopic mass 1 week, 2 weeks and 3 weeks after MTX treatment in women with abundant luteal blood flow was significantly larger (P < 0.05), and the time of serum β-hCG clearance and ectopic mass disappearance were significantly longer compared with those in women in the poor luteal blood flow group (P < 0.05).

CONCLUSIONS

Luteal blood flow might be a predictive factor for MTX treatment outcomes in women with unruptured tubal pregnancy, and those with abundant luteal blood flow need a longer recovery time.

Single-cell analysis of human ovarian cortex identifies distinct cell populations but no oogonial stem cells

The human ovary orchestrates sex hormone production and undergoes monthly structural changes to release mature oocytes. The outer lining of the ovary (cortex) has a key role in defining fertility in women as it harbors the ovarian reserve. It has been postulated that putative oogonial stem cells exist in the ovarian cortex and that these can be captured by DDX4 antibody isolation. Here, we report single-cell transcriptomes and cell surface antigen profiles of over 24,000 cells from high quality ovarian cortex samples from 21 patients. Our data identify transcriptional profiles of six main cell types; oocytes, granulosa cells, immune cells, endothelial cells, perivascular cells, and stromal cells. Cells captured by DDX4 antibody are perivascular cells, not oogonial stem cells. Our data do not support the existence of germline stem cells in adult human ovaries, thereby reinforcing the dogma of a limited ovarian reserve.

The potential function of endometrial-secreted factors for endometrium remodeling during the estrous cycle

Uterine has a pivotal role in implantation and conceptus development. To prepare a conducive uterine condition for possibly new gestation during the estrous cycle, uterine endometrium undergoes dramatic remodeling. In addition, angiogenesis is an indispensable biological process of endometrium remodeling. Furthermore, essential protein expressions related to important biological processes of endometrium remodeling, which are vascular endothelial growth factor (VEGF), myoglobin (MYG), collagen type IV (COL4), fucosyltransferase IV (FUT4), and cysteine-rich protein 2 (CRP2), were detected in the endometrial tissue reported in many previous studies and recently discovered in histotroph substrates during the estrous cycle. Those proteins, which are liable for provoking new vessel development, cell proliferation, cell adhesion, and cell migration, were expressed higher in the histotroph during the luteal phase than follicular phase. Histotroph proteins considerably contribute to endometrium remodeling during the estrous cycle. To that end, the following review will discuss and highlight the relevant information and evidence of the uterine fluid proteins as endometrial-secreted factors that adequately indicate the potential role of the uterine secretions to be involved in the endometrial remodeling process.

Hemodynamic changes detected by Doppler ultrasonography in the ovaries of cattle during early development of cystic ovarian disease

A common reproductive disease in dairy cattle is Cystic Ovarian Disease. To study its development, there was use of an experimental model of follicular persistence to detect hemodynamic changes occurring in ovaries by using Doppler ultrasonography. After estrous synchronization, control cows received no additional treatment and were evaluated at proestrus (CG), whereas treated cows (PG) received sub-luteal doses of progesterone for 15 days and were evaluated at proestrus, and after 0, 5, 10 and 15 days of follicular persistence. Spectral Doppler was used to evaluate blood flow in the ovarian artery, and power Doppler for evaluation of blood flow in the ovarian parenchyma and follicular wall of persistent and dominant preovulatory follicles. Findings using power Doppler signals indicated there were no differences between groups in the parenchyma of both right (P =  0.455) and left (P =  0.762) ovaries. In contrast, power Doppler signals of blood flow were less in walls of persistent follicles from day 0 to 15 when there was follicular persistence than in dominant follicles of the CG (P <  0.001). Blood flow in ovarian arteries was less (P <  0.05) in diastolic velocity and time averaged maximum velocity in all PG groups than in the CG. Peak systolic velocity was less (P <  0.05) in all PG than in the CG, with the exception of P15 (P >  0.05). These findings indicate there are marked changes in blood irrigation area of walls of persistent follicles during the 15 days of follicular persistence.

From a circle to a sphere: the ultrasound imaging of ovarian follicle with 2D and 3D technology

Ultrasound follicular count (antral follicle count, AFC) is a necessary tool for measuring ovarian reserve, whereby the estimated number of follicles responsive to FSH can predict the number of oocytes retrieved in IVF cycles and may be the basis for individualized ovarian stimulation therapy. Advances in the ultrasound technology have recently lead to the improvement in resolution and quality of the image. Moreover the automatic measurements of follicular diameter by using some specific 3D software seems associated to several advantages when compared to the 2D technique. Examination time is reduced because the ultrasound scan data are stored and can be analyzed in detail at a later time. These data can be reconstructed in any plane, regardless of the original scan plane facilitating the detailed analysis. Another advantage is that this new technique reduces the operator's influence on scan interpretation and objectivity; therefore, interobserver variability is reduced. Using follicular volume obtained with sono AVC as the measure of follicular growth combined with volume-based criteria for the hCG triggering may in the future improve the treatment outcome compared to that achieved with conventional monitoring with follicular diameter. Better knowledge in this area could be helpful to optimize IVF outcome, by refining ovarian stimulation protocols and obtain high quality oocytes.

The Role of Growth Hormone on Ovarian Functioning and Ovarian Angiogenesis

Although not yet well-understood, today it is clear that Growth Hormone (GH) exerts a relevant role in the regulation of ovulation and fertility; in fact, fertility is lower in women with GH deficiency (GHD), and GH receptors (GHR) and GH mRNA have been found in the ovary since the onset of follicular development in humans. However, despite the strong evidence of GH in the regulation of fertility, many aspects of GH actions at this level are still not well-established, and it is likely that some controversial data depend on the species analyzed, the dose of the hormone and the duration of use of GH. Folliculogenesis, ovulation, and corpus luteum formation and maintenance are processes that are critically dependent on angiogenesis. In the ovary, new blood vessel formation facilitates oxygen, nutrients, and hormone substrate delivery, and also secures transfer of different hormones to targeted cells. Some growth factors and hormones overlap their actions in order to control the angiogenic process for fertility. However, we still know very little about the factors that play a critical role in the vascular changes that occur during folliculogenesis or luteal regression. To promote and maintain the production of VEGF-A in granulosa cells, the effects of local factors such as IGF-I and steroids are needed; that VEGF-A-inducing effect cannot be induced by luteinizing hormone (LH) or chorionic gonadotropin (CG) alone. As a result of the influences that GH exerts on the hypothalamic-pituitary-gonadal axis, facilitating the release of gonadotropins, and given the relationship between GH and local ovarian factors such as VEGF-A, FGF-2, IGF-1, or production of sex steroids, we assume that GH has to be a necessary factor in ovarian angiogenesis, as it happens in other vascular beds. In this review we will discuss the actions of GH in the ovary, most of them likely due to the local production of the hormone and its mediators.

Synergy of Paracrine Signaling During Early-Stage Mouse Ovarian Follicle Development In Vitro

Introduction

Paracrine signals, such as soluble cytokines and extracellular matrix cues, are essential for the survival and development of multicellular ovarian follicles. While it is well established that hydrogel-based culture systems successfully support the growth of late-stage follicles for fertility preservation, growing small, early-stage ovarian follicles still proves to be challenging. We hypothesized that paracrine factors secreted from neighboring follicles may be crucial for improving the survival of early-stage follicles in vitro.

Methods

To test our hypothesis, we investigated the bi-directional crosstalk of the paracrine signals, such as cell-secreted cytokines, sex hormones and transcription factors (TFs), in follicles encapsulated and cultured for 12 days in alginate in groups of five (5×) and ten (10×).

Results

The differential profiles of TF activity and secretome during folliculogenesis were analyzed using TRanscriptional Activity CEllular aRray (TRACER) and data-driven multivariate modeling approach. The mechano- and oxygen-responsive TFs, NF-κB and HIF1, exhibited a unique upregulation signature in 10× follicles. Consistently, levels of proangiogenic factors, such as VEGF-A and angiopoietin-2, were significantly higher in 10× follicles than those in 5× follicles, reaching 269.77 and 242.82 pg/mL on the last day of culture. The analysis of TRACER and secreted cytokines also revealed critical early interactions between cytokines and TFs, correlating with the observed phenotypical and functional differences between conditions.

Conclusions

We identified unique signatures of synergism during successful early-stage ovarian follicle development. These findings bring us closer to understanding of mechanisms underlying the downstream effects of interactions between the extracellular microenvironment and early-stage folliculogenesis in vitro.

Imaging the ovary

During each reproductive cycle, the ovary exhibits tissue remodelling and cyclic vasculature changes associated with hormonally regulated folliculogenesis, follicle rupture, luteal formation and regression. However, the relationships among different types of follicles and corpora lutea are unclear, and the role of ovarian vasculature in folliculogenesis and luteal dynamics has not been extensively investigated. Understanding of ovarian physiology and pathophysiology relies upon elucidation of ovarian morphology and architecture. This paper summarizes the literature on traditional approaches to the imaging of ovarian structures and discusses recent advances in ovarian imaging. Traditional in-vivo ultrasound, together with histological and electron microscopic approaches provide detailed views of the ovary at organ, tissue and molecular levels. However, in-vivo imaging is limited to antral and larger follicles whereas histological imaging is mainly two-dimensional in nature. Also discussed are emerging approaches in the use of near-infrared fluorophores to image follicles in live animals to detect preantral follicles as well as visualizing ovarian structures using CLARITY in fixed whole ovaries to elucidate three-dimensional interrelationships among follicles, corpora lutea and ovarian vasculature. Advances in ovarian imaging techniques provide new understanding of ovarian physiology and allow for the development of better tools to diagnose ovarian pathophysiology.

The Effects of Administrated Sildenafil Citrate on Uterine Luminal Epithelium Height Associated with Ovarian Angiogenesis: An Experimental Animal Study

Background

Ovarian angiogenesis (OA) remains in lifetime and normal ovarian function depends to this continual remodeling of a complex vascular system. Endometrial thickness (ET) is one of the strongest predictors of successful implantation and pregnancy. Appropriate OA effects on ET by facilitating of ovarian hormone delivery.

Materials and Methods

Thirty adult female mice and twenty adult male mice were purchased. The female mice were divided into three groups: (1) control group without any intervention (n = 10), (2) gonadotropin group: receiving human menopausal gonadotropin (HMG) and human chorionic gonadotropin (n = 10), and (3) gonadotropin and sildenafil citrate (SC) group: receiving HMG and SC administration (n = 10). After mating, animals were deeply anesthetized, and the ovary and uterus was rapidly removed for histology and immunohistochemistry process.

Results

Four days after ovarian induction, all three layers of the uterus with specified thickness can be clearly seen. The heights of endometrial epithelial cells in gonadotropin group were not significantly different than those in control group. In gonadotropin and SC group, heights of the cells were significantly (P < 0.05) shorter than control and gonadotropin groups. ETs in all groups were not significantly deferent from each other (P > 0.05 each). Our results of immunohistochemistry survey for ovarian CD31 demonstrated that administrated SC increased OA but not significantly (P > 0.05 each).

Conclusion

It may finally conclude that administration of SC does not cause notable alterations in OA and ET; although for realistic decision about the SC effects on aforementioned parameters, more molecular investigations and longer drug consumption period are necessary.

Molecular regulation and role of angiogenesis in reproduction

Angiogenesis is an essential process for proper functioning of the female reproductive system and for successful pregnancy realization. The multitude of factors required for physiological angiogenesis and the complexity of regulation of their temporal-spatial activities contribute to aberrations in human fertilization and pregnancy outcomes. In this study, we reviewed the current knowledge of the temporal expression patterns, functions, and regulatory mechanisms of angiogenic factors during foliculogenesis, early implantation/placentation and embryo development, as well as recurrent spontaneous abortions. Angiogenic factors including vascular endothelial growth factors and angiopoietins have documented roles in the development of primordial follicles into mature antral follicles. They also participate in decidualization, which is accompanied by the creation of an extensive network of vessels in the stromal bed that support the growth of the embryo and the placenta, and maintain early pregnancy. During placentation angiogenic and angiomodulatory cytokines, T and B lymphocytes and macrophages affect angiogenesis in a context-dependent manner. Defects in angiogenesis at the maternal-fetal interface contribute to miscarriage in humans. The establishment of more polymorphisms in the genes involved in angiogenesis/vasculogenesis, and their pathological phenotype and expression could give opportunities for prediction, creating a therapeutic strategy, and treatment of diseases related to female reproductive health and problematic conception.

CLARITY reveals dynamics of ovarian follicular architecture and vasculature in three-dimensions

Optimal distribution of heterogeneous organelles and cell types within an organ is essential for physiological processes. Unique for the ovary, hormonally regulated folliculogenesis, ovulation, luteal formation/regression and associated vasculature changes lead to tissue remodeling during each reproductive cycle. Using the CLARITY approach and marker immunostaining, we identified individual follicles and corpora lutea in intact ovaries. Monitoring lifetime changes in follicle populations showed age-dependent decreases in total follicles and percentages of advanced follicles. Follicle development from primordial to preovulatory stage was characterized by 3 × 10⁵-fold increases in volume, decreases in roundness, and decreased clustering of same stage follicles. Construction of follicle-vasculature relationship maps indicated age- and gonadotropin-dependent increases in vasculature and branching surrounding follicles. Heterozygous mutant mice with deletion of hypoxia-response element in the vascular endothelial growth factor A (VEGFA) promoter showed defective ovarian vasculature and decreased ovulatory responses. Unilateral intrabursal injection of axitinib, an inhibitor of VEGF receptors, retarded neo-angiogenesis that was associated with defective ovulation in treated ovaries. Our approach uncovers unique features of ovarian architecture and essential roles of vasculature in organizing follicles to allow future studies on normal and diseased human ovaries. Similar approaches could also reveal roles of neo-angiogenesis during embryonic development and tumorigenesis.

Perifollicular blood flow and its relationship with endometrial vascularity, follicular fluid EG-VEGF, IGF-1, and inhibin-a levels and IVF outcomes

PURPOSE

The aim of this study is to investigate the association of perifollicular blood flow (PFBF) with follicular fluid EG-VEGF, inhibin-a, and insulin-like growth factor-1 (IGF-1) concentrations, endometrial vascularity, and IVF outcomes.

METHODS

Forty women with tubal factor infertility were included in a prospective cohort study. Each woman underwent IVF/ICSI procedure. Individual follicles of ≥16 mm (n = 156) were evaluated by power Doppler analysis and categorized as well-vascularized follicles (WVFs) or poorly vascularized follicles (PVFs). WVFs referred to those with perifollicular vascularity of 51-100 %. Each follicular fluid (FF) was individually aspirated and FF/serum EG-VEGF, inhibin-a, and FF IGF-1 levels were evaluated. Zones III-IV endometrial vascularity was classified as a well-vascularized endometrium (WVE). The presence of a WVE and mature oocytes, in addition to the embryo quality and clinical pregnancy rate (CPR), were recorded for each follicle. The main outcome measures were FF serum EG-VEGF, inhibin-a, IGF-1 levels, and WVE and IVF outcome per PFBF.

RESULTS

For WVFs, the level of FF EG-VEGF (p = 0.008), oocyte quality (p = 0.001), embryo quality (p = 0.002), a WVE (p = 0.001), and CPR (p = 0.04) increased significantly. The pregnant group was characterized by increased numbers of WVFs (p = 0.044), a WVE (p = 0.022), and increased levels of FF IGF-1 (p = 0.001) and serum EG-VEGF (p = 0.03). FF IGF-1 >50 ng/mL (AUC 0.72) had 75 % sensitivity and 64 % specificity for predicting CPR.

CONCLUSIONS

WVFs yield high-quality oocytes and embryos, a WVE, increased FF EG-VEGF levels, and increased CPRs.

Ovarian parameters and ovarian blood flow of women living in the area of environmental crisis

BACKGROUND AND OBJECTIVES

Exposure to environmental hazards will destroy a number of ovarian primordial follicles, reduce ovarian reserve and subsequent reproductive ability. This study designed to evaluate ovarian parameters and ovarian blood flow of women living in the area of environmental crisis Shalkar city (Kazakhstan) compared to women living in Aktobe city (Kazakhstan).

PATIENTS AND METHODS

220 women in their reproductive age studied and classified into two groups; study (Shalkar) group and control (Aktobe) group. Blood sample taken from studied women during follicular phase (day 3) for hormonal level evaluation including; follicle stimulating hormone (FSH) and anti-Mullerian hormone (AMH). Studied women evaluated using trans-vaginal ultrasound (TVS) to detect antral follicle count (AFC) during follicular scan and ovarian volume (OV), ovarian blood flow (OBF) using pulsatility index (PI) during follicular scan and luteal scan.

RESULTS

Both ovaries AFC was significantly less in study (Shalkar) group compared to and control (Aktobe) group (p=0.0001). Mean ovarian volume was significantly less in Shalkar group in both follicular phase and luteal phase (5.86±0.23 and 6.19±0.22Cm(3); respectively) compared to Aktobe group (6.85±0.19 and 6.92±0.18Cm(3); respectively). In addition, mean ovarian pulsatility index was significantly high with subsequent decrease in ovarian blood flow in Shalkar group in both follicular phase and luteal phase (3.36±0.20 and 3.45±0.19Cm/s; respectively) compared to Aktobe group (2.96±0.16 and 2.92±0.15Cm/s; respectively).

CONCLUSION

This study suggests definite environmental effect on ovarian parameters as indicated by decreased AFC, decreased both follicular and luteal OV and OBF in women living in environmental crisis Shalkar group compared to Aktobe group.

Targeted complement inhibition and microvasculature in transplants: a therapeutic perspective

Active complement mediators play a key role in graft-versus-host diseases, but little attention has been given to the angiogenic balance and complement modulation during allograft acceptance. The complement cascade releases the powerful proinflammatory mediators C3a and C5a anaphylatoxins, C3b, C5b opsonins and terminal membrane attack complex into tissues, which are deleterious if unchecked. Blocking complement mediators has been considered to be a promising approach in the modern drug discovery plan, and a significant number of therapeutic alternatives have been developed to dampen complement activation and protect host cells. Numerous immune cells, especially macrophages, develop both anaphylatoxin and opsonin receptors on their cell surface and their binding affects the macrophage phenotype and their angiogenic properties. This review discusses the mechanism that complement contributes to angiogenic injury, and the development of future therapeutic targets by antagonizing activated complement mediators to preserve microvasculature in rejecting the transplanted organ.

Expression and localization of vascular endothelial growth factor A (VEGFA) and its two receptors (VEGFR1/FLT1 and VEGFR2/FLK1/KDR) in the canine corpus luteum and utero-placental compartments during pregnancy and at normal and induced parturition

VEGFA is one of the most potent known inducers of angiogenesis. However, the function of angiogenic factors in the canine corpus luteum (CL) of pregnancy and in the pregnant uterus and placenta has not yet been elucidated. Therefore, here we investigated the expression and localization of VEGFA and its receptors (VEGFR1/FLT1 and VEGFR2/FLK1/KDR) in the canine CL and utero-placental compartments (ut-pl) throughout pregnancy until prepartum luteolysis. Antigestagen-mediated effects on expression of VEGF system in ut-pl were elucidated in mid-pregnant dogs. While displaying high individual variation, the luteal VEGFA was elevated during pre-implantation and post-implantation, followed by a decrease during mid-gestation, which was more pronounced at the mRNA level, and showed constant expression afterwards. Within the uterus, it increased following implantation and during mid-gestation in ut-pl compartments, but was downregulated at prepartum luteolysis. Luteal VEGFR1 expression resembled that of VEGFA; VEGFR2 remained unaffected throughout pregnancy. In ut-pl compartments, both receptors increased gradually towards mid-gestation; a prepartum decrease was observed for VEGFR1. Antigestagen-treatment resulted in decreased expression of ut-pl VEGFR1. In the CL, VEGFA stained in luteal cells. Uterine signals of VEGFA and its two receptors were observed in epithelial and vascular compartments, and in myometrium. In placental labyrinth, additionally, trophoblast stained positively. Luteal VEGFR1 was localized to the luteal cells and tunica media of blood vessels, whereas VEGFR2 stained only in capillary endothelial cells. The upregulation of luteal and the ut-pl VEGF system during early gestational stages supports the increased vascularization rate during this time. The diminishing effects of the prepartum endocrine milieu on VEGFA function seem to be more pronounced in the ut-pl units.

Effect of Local Basic Fibroblast Growth Factor and Vascular Endothelial Growth Factor on Subcutaneously Allotransplanted Ovarian Tissue in Ovariectomized Mice

Objective

One of the major obstacles to ovarian tissue preservation is delayed angiogenesis that leads follicles lost after transplantation. The aim of the present study was to investigate the effects of bFGF and VEGF on heterotopic transplanted ovarian tissue using a mouse model.

Methods

Female mice underwent bilateral ovariectomy. Ovarian tissues encapsulated by fibrin hydrogels were transplanted subcutaneously into recipient mice, in which ovarian hormonal cyclicity was absent. The fibrinogen solution was mixed with bFGF, VEGF, or a mixture of bFGF and VEGF. The grafts were recovered 21 days after transplantation. Follicle morphology and follicle numbers were observed by H&E staining. Blood vessels were observed in transplanted intra-ovarian tissue by CD31 antibody IHC staining. Daily vaginal cytology was performed to determine estrous cycle and functional restoration of transplanted ovarian tissue. Blood was collected weekly and serum FSH levels were measured with a radioimmunoassay kit. Apoptosis analysis was performed by anti-AC-3 staining and survivin mRNA expression.

Results

The number of primordial follicles and secondary follicles in the bFGF+VEGF group was significantly higher than in the control group. The vascular density in the bFGF+VEGF groups were significantly higher than in the bFGF and the VEGF groups; there was no significant difference between the bFGF and VEGF groups. Estrous cycle was earlier in the bFGF+VEGF group compared with the control group; all mice in this group restored ovarian function. Serum FSH levels in the bFGF+VEGF group were significantly lower than in the control group by day 14 post-transplantation. The AC-3-positive in control group was significantly higher compared with bFGF group and VEGF group, and in bFGF+VEGF group was significantly lower than bFGF group and VEGF group. Survivin mRNA expression in bFGF+VEGF group was significantly higher than control group.

Conclusion

The combination of bFGF and VEGF has beneficial effects on follicle survival, angiogenesis, and resumption of estrous cycles.

The effect of leptin on luteal angiogenic factors during the luteal phase of the estrous cycle in goats

Fibroblast growth factor 2 (FGF2), angiopoietin 1 (Ang1), and vascular endothelial growth factor (VEGF) are angiogenic factors implicated in the vascular development of the corpus luteum (CL). Each factor is regulated or influenced by leptin in non-ovarian tissues. Moreover, leptin and its receptor, ObRb, have been identified in luteal tissue throughout the luteal phase. Therefore, leptin is hypothesized to influence luteal vasculature through the regulation of FGF2, Ang1, and VEGF. Multiparous, cycling crossbred female goats (does) were allocated to early (n=12), mid (n=8), and late (n=11) stages of the luteal phase for CL collection. Luteal tissue was harvested and either snap frozen in liquid N2, paraffin embedded, or cultured with leptin (0, 10(-12), 10(-11), 10(-10), 10(-9), 10(-8)M). Tissue was analyzed for FGF2, Ang1, VEGF, ObRb, and leptin expression. Angiopoietin 1, FGF2, VEGF expression was higher (P≤0.001) in the mid-luteal stage than the early stage. Expression decreased (P≤0.001) during the late luteal stage with the exception of VEGF, which remained elevated. In contrast, leptin and ObRb were lowest (P≤0.003) during the mid-luteal stage compared to the early and late stages. All factors were detected in and/or around vessels in early stage tissue compared to mid and late stages. Leptin stimulated (P≤0.02) Ang1, FGF2, and VEGF expression only in early stage luteal cultures. Collectively, these data provide evidence that leptin may be involved in the luteal angiogenic process during the early stage of CL formation.

Proliferation of luteal steroidogenic cells in cattle

The rapid growth of the corpus luteum (CL) after ovulation is believed to be mainly due to an increase in the size of luteal cells (hypertrophy) rather than an increase in their number. However, the relationship between luteal growth and the proliferation of luteal steroidogenic cells (LSCs) is not fully understood. One goal of the present study was to determine whether LSCs proliferate during CL growth. A second goal was to determine whether luteinizing hormone (LH), which is known have roles in the proliferation and differentiation of follicular cells, also affects the proliferation of LSCs. Ki-67 (a cell proliferation marker) was expressed during the early, developing and mid luteal stages and some Ki-67-positive cells co-expressed HSD3B (a steroidogenic marker). DNA content in LSCs isolated from the developing CL increased much more rapidly (indicating rapid growth) than did DNA content in LSCs isolated from the mid CL. The cell cycle-progressive genes CCND2 (cyclin D2) and CCNE1 (cyclin E1) mRNA were expressed more strongly in the small luteal cells than in the large luteal cells. LH decreased the rate of increase of DNA in LSCs isolated from the mid luteal stage but not in LSCs from the developing stage. LH suppressed CCND2 expression in LSCs from the mid luteal stage but not from the developing luteal stage. Furthermore, LH receptor (LHCGR) mRNA expression was higher at the mid luteal stage than at the developing luteal stage. The overall results suggest that the growth of the bovine CL is due to not only hypertrophy of LSCs but also an increase in their number, and that the proliferative ability of luteal steroidogenic cells decreases between the developing and mid luteal stages.

Vascular endothelial growth factor and angiopoietin production by primate follicles during culture is a function of growth rate, gonadotrophin exposure and oxygen milieu

STUDY QUESTION

What is the time course of production of vascular endothelial growth factor-A (VEGF-A), angiopoietin (ANGPT)-1 and ANGPT-2 by primate follicles during encapsulated three-dimensional culture, and what conditions affect their production?

SUMMARY ANSWER

Primate follicles produce VEGF-A and ANGPT-2 in vitro, particularly after developing to the antral stage, with VEGF production influenced by FSH concentration and O(2) tension.

WHAT IS KNOWN ALREADY

Folliculogenesis, i.e. the development of primordial follicles into mature, antral follicles, requires the creation of a vascular network in the follicle wall via a process called angiogenesis. Angiogenic factors including VEGFs and ANGPTs have documented roles in angiogenesis. However, direct studies on the production and regulation of angiogenic factors by individual, growing follicles are limited.

STUDY DESIGN, SIZE, DURATION

Ovaries (n = 9 pairs) were obtained from rhesus macaques during the early follicular phase of the menstrual cycle (cycle days 1-4). Secondary (125-225 µm) follicles were isolated mechanically, encapsulated into alginate (0.25% w/v) and cultured for 40 days.

MATERIALS, SETTING, METHODS

Individual follicles were cultured in a 5 or 20% O(2) environment in alpha minimum essential medium supplemented with recombinant human (h) FSH. Half of the follicles had recombinant hLH added to the media from Days 30 to 40. Follicle diameters were measured weekly. Follicles were categorized at Week 5 as no-grow (NG; <250 μm in diameter), slow-grow (SG; 251-499 μm) and fast-grow (FG; >500 μm). VEGF-A, ANGPT-1 and -2 concentrations in media were measured by ELISA.

MAIN RESULTS AND THE ROLE OF CHANCE

VEGF concentrations were low throughout the culture for NG follicles. SG and FG follicles had detectable VEGF concentrations at Week 2, which continued to rise throughout culture. VEGF concentrations were distinct (P < 0.05) among all three follicle categories during Weeks 4 and 5. VEGF concentrations were higher (P < 0.05) in SG follicles in the presence of high/mid-dose FSH at 5% O(2). In contrast, there were no dose-dependent differences in VEGF production for FG follicles based on FSH concentrations or O(2) tension. At Week 5, follicles that produced metaphase II oocytes, following exposure to an ovulatory hCG dose, secreted higher concentrations of VEGF than those containing germinal vesicle-intact oocytes. Media concentrations of ANGPT-1 were low throughout culture for all three follicle categories. ANGPT-2 concentrations were low throughout culture for NG follicles. In contrast, ANGPT-2 concentrations of SG and FG follicles continued to rise from Weeks 1 to 4. During Weeks 2-4, ANGPT-2 concentrations in FG follicles were significantly higher than those of SG and NG follicles (P < 0.05).

LIMITATION, REASONS FOR CAUTION

This study reports VEGF-A, ANGPT-1 and -2 production by in vitro-developed individual primate (macaque) follicles, that is limited to the interval from the secondary to small antral stage. After VEGF and ANGPT-1 assays, the limited remaining samples did not allow assessment of the independent effects of gonadotrophin and O(2) on the ANGPT-2 production by cultured follicles. Findings await translation to human follicles.

WIDER IMPLICATION OF THE FINDINGS

The above findings provide novel information on the process of primate follicle maturation. We hypothesize that a symbiotic relationship between elevated concentrations of ANGPT-2 and VEGF allows FG antral follicles to excel in follicle maturation, e.g. by promoting its vascularization. Elevated ANGPT-2 may also offer possible insight into future oocyte quality as early as Week 2, compared with Week 4 for VEGF and follicle size.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by the following grants: NIH U54 RR024347/HD058294/PL1-EB008542 (Oncofertility Consortium), NIH U54-HD018185 (SCCPIR), NIH ORWH/NICHD 2K12HD043488 (BIRCWH), NIH FIC TW/HD-00668, ONPRC 8P51OD011092. There are no conflicts of interest to declare.

Endocrine and local control of the primate corpus luteum

The primate corpus luteum is a transient endocrine gland that differentiates from the ovulatory follicle midway through the ovarian (menstrual) cycle. Its formation and limited lifespan is critical for fertility, as luteal-derived progesterone is the essential steroid hormone required for embryo implantation and maintenance of intra-uterine pregnancy until the placenta develops. It is well-established that LH and the LH-like hormone, CG, are the vital luteotropic hormones during the menstrual cycle and early pregnancy, respectively. Recent advances, particularly through genome analyses and cellular studies, increased our understanding of various local factors and cellular processes associated with the development, maintenance and repression of the corpus luteum. These include paracrine or autocrine factors associated with angiogenesis (e.g., VEGF), and that mediate LH/CG actions (e.g., progesterone), or counteract luteotropic effects (i.e., local luteolysis; e.g., PGF2α). However, areas of mystery and controversy remain, particularly regarding the signals and events that initiate luteal regression in the non-fecund cycle. Novel approaches capable of gene "knockdown" or amplification", in vivo as well as in vitro, should identify novel or underappreciated gene products that are regulated by or modulate LH/CG actions to control the functional lifespan of the primate corpus luteum. Further advances in our understanding of luteal physiology will help to improve or control fertility for purposes ranging from preservation of endangered primate species to designing novel ovary-based contraceptives and treating ovarian disorders in women.

VEGF and bFGF increase survival of xenografted human ovarian tissue in an experimental rabbit model

PURPOSE

The aim of this study is to determine whether vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) could increase the survival of xenografted human ovarian tissue in an experimental rabbit model.

METHODS

Fresh human ovarian tissue was xenotransplanted into the back muscle of 25 castrated female New Zealand rabbits for 6 weeks with the immunosuppression of FTY720 (2 mg/kg/d). Rabbits were randomly divided into five experimental groups: (A) graft and host treatment with VEGF (50 ng/ml); (B) graft and host treatment with bFGF (100 ng/ml); (C) graft and host treatment with VEGF(50 ng/ml) + bFGF (100 ng/ml); (D) graft and host treatment with normal saline; (E) control group, no treatment. 4 weeks after transplantation, human menopausal gonadotropin (HMG) 10 IU was administered every second day in group A, group B, group C and group D for 2 weeks. Graft survival was assessed by graft recovery rate, histological analysis, immunohistochemical staining for CD31 and Ki-67expression, TUNEL assay.

RESULTS

After 6 weeks of grafting, the number of CD31-positive stained cells increased significantly in group A, group B and group C compared to the control group. All groups showed strong Ki-67 immunostaining in ovarian stroma. Only one rabbit in group C retained the grafts' follicles. Grafting resulted in relative lower fibrosis in group A and group C compared to the control group. Apoptosis was significantly lower in group C compared to the control group.

CONCLUSIONS

Fresh human ovarian cortex grafted into the back muscle of rabbit can sustain part of ovarian tissue function with the immunosuppression of FTY720, although follicle number diminishes significantly after grafting. The administration of VEGF and bFGF, especially the combination of them, may trigger angiogenesis, reduce apoptosis and fibrosis, increase survival in transplanted human ovarian tissue.