Regulation of vascular endothelial growth factor-A and its soluble receptor sFlt-1 by luteinizing hormone in vivo: implication for ovarian follicle angiogenesis

Up-regulated mRNA expression of VEGFA receptors (FLT1 and KDR) in placentas after assisted reproductive technology fertilization

Placental angiogenesis is a pivotal process for feto-maternal circulation and ensures efficient development of the placenta throughout pregnancy. Many factors during in vitro fertilization and embryo transfer procedures may affect placental gene expression and fetus development. The present study aimed to identify differences in angiogenesis-related gene (VEGFA, FGF2, FLT1, and KDR) expression profiles in placentas after assisted reproductive technology fertilization and natural conception in healthy women. In a case-control study, term placentas were collected from Caucasian women after assisted reproductive technology fertilization (N = 20) and after natural conception in women with uncomplicated pregnancy (N = 9). The mRNA expression in placentas was examined for VEGFA, FGF2, FLT1, and KDR genes by real-time quantitative polymerase chain reaction (RT-qPCR). Group stratification was performed for comparison of investigated genes between the type of embryo transferred (fresh/frozen), place of tissue donation (center/margin), and newborns' gender (male/female). In the ART placentas, significant down-regulation of VEGFA gene (p = 0.016) and up-regulation of FLT1 (p = 0.026) and KDR (p < 0.001) gene receptors were observed. Genes encoding VEGFA receptors were up-regulated in both fresh (ET) and frozen (FET) embryo transfer groups compared to controls. For the FLT1 gene, a statistically significant difference was observed between the frozen embryo transfer group and the controls (p = 0.032). Relative expression of KDR was significantly higher for both embryo transfer groups compared to controls (p < 0.001) and between ET and FET (p = 0.002). No statistically significant differences were observed between placental expression in different places of tissue donation and newborns' gender. We observed differences in the placental expression of VEGFA and its receptors FLT1 and KDR in pregnancies after assisted reproductive technology compared to naturally conceived pregnancies. More research is needed to clarify these alterations that may affect placental development and fetal health.

Inducing Angiogenesis in the Nucleus Pulposus

Bone morphogenetic protein (BMP) gene delivery to Lewis rat lumbar intervertebral discs (IVDs) drives bone formation anterior and external to the IVD, suggesting the IVD is inhospitable to osteogenesis. This study was designed to determine if IVD destruction with a proteoglycanase, and/or generating an IVD blood supply by gene delivery of an angiogenic growth factor, could render the IVD permissive to intra-discal BMP-driven osteogenesis and fusion. Surgical intra-discal delivery of naïve or gene-programmed cells (BMP2/BMP7 co-expressing or VEGF165 expressing) +/- purified chondroitinase-ABC (chABC) in all permutations was performed between lumbar 4/5 and L5/6 vertebrae, and radiographic, histology, and biomechanics endpoints were collected. Follow-up anti-sFlt Western blotting was performed. BMP and VEGF/BMP treatments had the highest stiffness, bone production and fusion. Bone was induced anterior to the IVD, and was not intra-discal from any treatment. chABC impaired BMP-driven osteogenesis, decreased histological staining for IVD proteoglycans, and made the IVD permissive to angiogenesis. A soluble fragment of VEGF Receptor-1 (sFlt) was liberated from the IVD matrix by incubation with chABC, suggesting dysregulation of the sFlt matrix attachment is a possible mechanism for the chABC-mediated IVD angiogenesis we observed. Based on these results, the IVD can be manipulated to foster vascular invasion, and by extension, possibly osteogenesis.

An ex vivo ovulation system enables the discovery of novel ovulatory pathways and nonhormonal contraceptive candidates†

Ovulation is an integral part of women's menstrual cycle and fertility. Understanding the mechanisms of ovulation has broad implications for the treatment of anovulatory diseases and the development of novel contraceptives. Now, few studies have developed effective models that both faithfully recapitulate the hallmarks of ovulation and possess scalability. We established a three-dimensional encapsulated in vitro follicle growth (eIVFG) system that recapitulates folliculogenesis and produces follicles that undergo ovulation in a controlled manner. Here, we determined whether ex vivo ovulation preserves molecular signatures of ovulation and demonstrated its use in discovering novel ovulatory pathways and nonhormonal contraceptive candidates through a high-throughput ovulation screening. Mature murine follicles from eIVFG were induced to ovulate ex vivo using human chorionic gonadotropin and collected at 0, 1, 4, and 8 hours post-induction. Phenotypic analyses confirmed key ovulatory events, including cumulus expansion, oocyte maturation, follicle rupture, and luteinization. Single-follicle RNA-sequencing analysis revealed the preservation of ovulatory genes and dynamic transcriptomic profiles and signaling. Soft clustering identified distinct gene expression patterns and new pathways that may critically regulate ovulation. We further used this ex vivo ovulation system to screen 21 compounds targeting established and newly identified ovulatory pathways. We discovered that proprotein convertases activate gelatinases to sustain follicle rupture and do not regulate luteinization and progesterone secretion. Together, our ex vivo ovulation system preserves molecular signatures of ovulation, presenting a new powerful tool for studying ovulation and anovulatory diseases as well as for establishing a high-throughput ovulation screening to identify novel nonhormonal contraceptives for women.

Effects of P4 Antagonist RU486 on VEGF and Its Receptors' Signaling during the In Vivo Transition from the Preovulatory to Periovulatory Phase of Ovarian Follicles

The development of an adequate blood vessel network is crucial for the accomplishment of ovarian follicle growth and ovulation, which is necessary to support the proliferative and endocrine functions of the follicular cells. Although the Vascular Endothelial Growth Factor (VEGF) through gonadotropins guides ovarian angiogenesis, the role exerted by the switch on of Progesterone (P4) during the periovulatory phase remains to be clarified. The present research aimed to investigate in vivo VEGF-mediated mechanisms by inducing the development of periovulatory follicles using a pharmacologically validated synchronization treatment carried out in presence or absence of P4 receptor antagonist RU486. Spatio-temporal expression profiles of VEGF, FLT1, and FLK1 receptors and the two major MAPK/ERKs and PI3K/AKT downstream pathways were analyzed on granulosa and on theca compartment. For the first time, the results demonstrated that in vivo administration of P4 antagonist RU486 inhibits follicular VEGF receptors' signaling mainly acting on the theca layer by downregulating the activation of ERKs and AKTs. Under the effect of RU486, periovulatory follicles' microarchitecture did not move towards the periovulatory stage. The present evidence provides new insights on P4 in vivo biological effects in driving vascular and tissue remodeling during the periovulatory phase.

Functional response of systemic and intrafollicular placental growth factor in cycling mares

The aim of the study was to assess the physiological reference values for systemic and intrafollicular placental growth factor (PlGF) concentrations in different categories of follicular sizes in cycling mares, according to progesterone (P4) and oestradiol (E2) patterns. Sixty ovaries were taken after slaughter from 30 clinically healthy mares. Regarding their size, the follicles were classified into three different categories, i.e. small (20-30 mm), medium-sized (31-40 mm) and large (≥41 mm), and follicular fluid (FF) was sampled from each single follicle. Intrafollicular PlGF concentrations were significantly increased in larger and medium-sized follicles compared to small follicles, and their values were 1.48 and 1.36 times higher than the systemic values, respectively. On the other hand, systemic PlGF concentrations were 1.3 times higher than those in the FF of follicles of small size. Intrafollicular P4 concentrations were significantly higher in larger follicles than in small ones, and their concentrations were 6.74 and 3.42 times higher than the systemic values, respectively. Intrafollicular E2 concentrations were significantly higher in large and medium-sized follicles than in follicles of small size, and their concentrations were 21.1, 15.4 and 8.35 times higher than the systemic values, respectively. Intrafollicular and systemic PlGF concentrations were strongly and positively correlated; nevertheless, no correlations between intrafollicular and systemic steroid hormones, PlGF and follicle diameters, PlGF and E2, or PlGF and P4 were observed. This represents the first study to characterise systemic and intrafollicular PlGF concentrations in cycling normal mares, providing evidence that the bioavailability of this factor in follicles of medium and large sizes was higher than in small follicles, independently of steroid hormone concentrations. Further studies are needed to assess the presumable implications of PlGF in follicular angiogenesis in mares, similar to those already observed in women and primates.

Insulin-like growth factor-1 and soluble FMS-like tyrosine kinase-1 prospectively predict cancelled IVF cycles

PURPOSE

To identify biomarkers that prospectively predict IVF cycle cancellation.

METHODS

In this prospective study, sera were obtained prior to any intervention, from women about to undergo an IVF cycle. The sera were assayed by ELISA for levels of insulin-like growth factor (IGF)-1, IGF-2, IGF binding protein (BP)-1, and soluble fms-like tyrosine kinase (sFLT-1). The cancellation or progression of the IVF cycle was subsequently obtained by chart review. Associations between serum components and outcome were analyzed by the Mann-Whitney test. Receiver operator curves were constructed to evaluate the strength of the correlations between biomarkers and cycle cancellation, as assessed from the area under the curve (AUC).

RESULTS

A total of 205 women were included. Twenty-seven (13.2%) cycle cancellations due to poor response were recorded. Women with a cancelled cycle had reduced anti-Mullerian hormone (AMH) values (p < 0.001) and antral follicle count (p = 0.003). There were no significant differences between the two groups with regard to age and BMI. Median concentrations of IGF-1 and sFLT-1 were elevated in sera from women whose IVF cycles were cancelled as compared to those with ongoing cycles (p = 0.015 and p < 0.001, respectively); AUC for IGF-1 and sFLT-1 were 0.67 and 0.75, respectively. Concentrations of sFLT-1 remained significantly higher in patients with cancelled cycles even after controlling for AMH levels. There were no differences in IGF-2 and IGFBP-1 levels between the two groups.

CONCLUSIONS

Measurement of circulating IGF-1 and sFLT-1 levels prior to initiation of an IVF cycle has the potential to identify women whose cycles have an increased likelihood to be subsequently cancelled.

Ovulation: Parallels With Inflammatory Processes

The midcycle surge of LH sets in motion interconnected networks of signaling cascades to bring about rupture of the follicle and release of the oocyte during ovulation. Many mediators of these LH-induced signaling cascades are associated with inflammation, leading to the postulate that ovulation is similar to an inflammatory response. First responders to the LH surge are granulosa and theca cells, which produce steroids, prostaglandins, chemokines, and cytokines, which are also mediators of inflammatory processes. These mediators, in turn, activate both nonimmune ovarian cells as well as resident immune cells within the ovary; additional immune cells are also attracted to the ovary. Collectively, these cells regulate proteolytic pathways to reorganize the follicular stroma, disrupt the granulosa cell basal lamina, and facilitate invasion of vascular endothelial cells. LH-induced mediators initiate cumulus expansion and cumulus oocyte complex detachment, whereas the follicular apex undergoes extensive extracellular matrix remodeling and a loss of the surface epithelium. The remainder of the follicle undergoes rapid angiogenesis and functional differentiation of granulosa and theca cells. Ultimately, these functional and structural changes culminate in follicular rupture and oocyte release. Throughout the ovulatory process, the importance of inflammatory responses is highlighted by the commonalities and similarities between many of these events associated with ovulation and inflammation. However, ovulation includes processes that are distinct from inflammation, such as regulation of steroid action, oocyte maturation, and the eventual release of the oocyte. This review focuses on the commonalities between inflammatory responses and the process of ovulation.

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.

Toxico-pathological effects of meglumine antimoniate on human umbilical vein endothelial cells

Leishmaniasis is one of the most important parasitic diseases after malaria. The standard treatment of leishmaniasis includes pentavalent antimonials (SbV); however, these drugs are associated with serious adverse effects. There have been very few studies pertaining to their side effects and mechanism of action in the fetus. This investigation examines the effects of meglumine antimoniate (MA) on the survival rate, angiogenesis and cellular apoptosis in the human umbilical vein endothelial cells (HUVECs). HUVECs were treated with varying doses of MA (100-800 μg/ml) for 24, 48 and 72 h and the survival rate was studied by colorimetric assay, flow cytometry, immunocytochemistry, migration (scratch) assay and tube formation assay. The results of quantitative real-time PCR (qPCR) studies indicated that the most important genes involved in presenting angiogenesis included VEGF and its receptors (Kdr and Flt-1), NP1 and Hif-1α genes including the anti-apoptotic gene of Bcl2, were significantly reduced compared to the control group (p < 0.05). In contrast, the most leading genes involved in the phenomenon of apoptosis were P53, Bax, Bak, Apaf-1 and caspases 3, 8 and 9, which were significantly up regulated compared to the control group (p < 0.05).

Concentration of soluble urokinase plasminogen activator receptor (suPAR) in the pre-ovulatory follicular fluid is associated with development of ovarian hyperstimulation syndrome during ovarian stimulation

PURPOSE

Investigating whether pre-ovulatory follicular fluid (FF) levels of selected proteins differ between women who do or do not develop severe ovarian hyperstimulation syndrome (OHSS) and evaluate whether they potentially could guide a "freeze-all" strategy.

METHODS

FF was collected during a randomized controlled trial comparing OHSS in antagonist versus agonist protocol including 1050 women in their first assisted reproductive technology (ART) cycle during year 2009-2013. The present sub-study is a matched case-control study comparing FF levels of soluble urokinase plasminogen activator receptor (suPAR), C-reactive protein, placental growth factor, vascular endothelial growth factor, and angiopoietins 1 and 2 in OHSS cases (n = 25, severe OHSS, and ≥ 15 oocytes), high-risk controls (n = 25, no OHSS, and ≥ 15 oocytes), and low-risk controls (n = 25, no OHSS, and 5-8 oocytes).

RESULTS

FF level of suPAR differed significantly between the three groups (p = 0.018) with mean (SD) levels of 2.3 (0.4) μg/L, 2.6 (0.8) μg/L, and 2.8 (0.6) μg/L in OHSS cases, high-risk controls, and low-risk controls, respectively. Receiver operating characteristic curve analysis demonstrated that suPAR levels could predict severe OHSS (AUC 0.678; 95% CI 0.553-0.803) with a sensitivity of 64% and a specificity of 66%. None of the other investigated proteins differed between the three groups or between OHSS cases and combined controls.

CONCLUSION

The pre-ovulatory FF level of suPAR was significantly lower in women developing severe OHSS, indicating that the plasminogen activator system could be involved in the pathophysiology of OHSS. However, suPAR did not provide a satisfying predictive value for the prediction of OHSS.

Vascular endothelial growth factors C and D may promote angiogenesis in the primate ovulatory follicle

Angiogenesis in the ovary occurs rapidly as the ovarian follicle transforms into a mature corpus luteum. Granulosa cells produce vascular endothelial growth factor A (VEGFA) in response to the ovulatory gonadotropin surge. VEGFA is established as a key mediator of angiogenesis in the primate ovulatory follicle. To determine if additional VEGF family members may be involved in angiogenesis within the ovulatory follicle, cynomolgus monkeys (Macaca fascicularis) received gonadotropins to stimulate multiple follicular development, and human chorionic gonadotropin (hCG) substituted for the luteinizing hormone surge to initiate ovulatory events. Granulosa cells of monkey ovulatory follicles contained mRNA and protein for VEGFC and VEGFD before and after hCG administration. VEGFC and VEGFD were detected in monkey follicular fluid and granulosa cell-conditioned culture media, suggesting that granulosa cells of ovulatory follicles secrete both VEGFC and VEGFD. To determine if these VEGF family members can stimulate angiogenic events, monkey ovarian microvascular endothelial cells (mOMECs) were obtained from monkey ovulatory follicles and treated in vitro with VEGFC and VEGFD. Angiogenic events are mediated via three VEGF receptors; mOMECs express all three VEGF receptors in vivo and in vitro. Exposure of mOMECs to VEGFC increased phosphorylation of AKT, while VEGFD treatment increased phosphorylation of both AKT and CREB. VEGFC and VEGFD increased mOMEC migration and the formation of endothelial cell sprouts in vitro. However, only VEGFD increased mOMEC proliferation. These findings suggest that VEGFC and VEGFD may work in conjunction with VEGFA to stimulate early events in angiogenesis of the primate ovulatory follicle.

Distinct effect of fetal bovine serum versus follicular fluid on multipotentiality of human granulosa cells in in vitro condition

This study aimed to develop an appropriate medium for preservation of multipotentiality in human granulosa cells. To compare the possible effect of different media supplemented with follicular fluid or fetal bovine serum, granulosa cells were cultured in vitro over a period of 14 days. Stemness feature and any alteration in the cell phenotype were monitored using colony count assay and flow cytometry analysis by monitoring the expression of Oct3/4 and GATA-4 factors. Transcript expression level of Sox-2, Klf-4, and Nanog were investigated using quantitative real-time PCR analysis. Cells were cultured in the medium supplement with follicular fluid showed normal cell morphology and epithelial-like appearance, however, cells treated with fetal bovine serum, exhibited the clonogenic potential of granulosa cells which was increased after exposure to follicular fluid after 14 days (p < 0.05). Flow cytometry analysis revealed a significant reduction in the protein level of GATA-4 in cells cultured in presence of follicular fluid compared with cells received fetal bovine serum (p < 0.001). Quantitative real-time PCR analysis disclosed reduction of Sox-2, Klf-4 and Nanog levels in cells exposed to fetal bovine serum. Our experiment showed the exposure of human granulosa cells to follicular fluid efficiently preserves the stemness characteristics of the cells.

Placental Growth Factor Is Required for Ovulation, Luteinization, and Angiogenesis in Primate Ovulatory Follicles

Placental growth factor (PGF) is member of the vascular endothelial growth factor (VEGF) family of angiogenesis regulators. VEGFA is an established regulator of ovulation and formation of the corpus luteum. To determine whether PGF also mediates aspects of ovulation and luteinization, macaques received gonadotropins to stimulate multiple follicular development. Ovarian biopsies and whole ovaries were collected before (0 hours) and up to 36 hours after human chorionic gonadotropin (hCG) administration to span the ovulatory interval. PGF and VEGFA were expressed by both granulosa cells and theca cells. In follicular fluid, PGF and VEGFA levels were lowest before hCG. PGF levels remained low until 36 hours after hCG administration, when PGF increased sevenfold to reach peak levels. Follicular fluid VEGFA increased threefold to reach peak levels at 12 hours after hCG, then dropped to intermediate levels. To explore the roles of PGF and VEGFA in ovulation, luteinization, and follicular angiogenesis in vivo, antibodies were injected into the follicular fluid of naturally developed monkey follicles; ovariectomy was performed 48 hours after hCG, with ovulation expected about 40 hours after hCG. Intrafollicular injection of control immunoglobulin G resulted in no retained oocytes, follicle rupture, and structural luteinization, including granulosa cell hypertrophy and capillary formation in the granulosa cell layer. PGF antibody injection resulted in oocyte retention, abnormal rupture, and incomplete luteinization, with limited and disorganized angiogenesis. Injection of a VEGFA antibody resulted in oocyte retention and very limited follicle rupture or structural luteinization. These studies demonstrate that PGF, in addition to VEGFA, is required for ovulation, luteinization, and follicular angiogenesis in primates.

Human umbilical cord mesenchymal stem cells improve the reserve function of perimenopausal ovary via a paracrine mechanism

Background

Human umbilical cord mesenchymal stem cells (hUCMSCs) are a type of pluripotent stem cell which are isolated from the umbilical cord of newborns. hUCMSCs have great therapeutic potential. We designed this experimental study in order to investigate whether the transplantation of hUCMSCs can improve the ovarian reserve function of perimenopausal rats and delay ovarian senescence.

Method

We selected naturally aging rats confirmed by vaginal smears as models of perimenopausal rats, divided into the control group and the treatment group, and selected young fertile female rats as normal controls. hUCMSCs were transplanted into rats of the treatment group through tail veins. Enzyme-linked immunosorbent assay (ELISA) detected serum levels of sex hormones, H&E staining showed ovarian tissue structure and allowed follicle counting, immunohistochemistry and western blot analysis revealed ovarian expression of hepatocyte growth factor (HGF), vascular endothelial cell growth factor (VEGF), and insulin-like growth factor-1 (IGF-1), polymerase chain reaction (PCR) and western blot analysis revealed hUCMSCs expression of HGF, VEGF, and IGF-1.

Results

At time points of 14, 21, and 28 days after hUCMSCs transplantation, estradiol (E₂) and anti-Müllerian hormone (AMH) increased while follicle-stimulating hormone (FSH) decreased; ovarian structure improved and follicle number increased; ovarian expression of HGF, VEGF, and IGF-1 protein elevated significantly. Meanwhile, PCR and western blot analysis indicated hUCMSCs have the capacity of secreting HGF, VEGF, and IGF-1 cytokines.

Conclusions

Our results suggest that hUCMSCs can promote ovarian expression of HGF, VEGF, and IGF-1 through secreting those cytokines, resulting in improving ovarian reserve function and withstanding ovarian senescence.

Interactive cooperation and hierarchical operation of microRNA and transcription factor crosstalk in human transcriptional regulatory network

Transcriptional regulation of gene expression is an essential cellular process that is arranged by transcription factors (TFs), microRNAs (miRNA) and their target genes through a variety of mechanisms. Here, we set out to reconstruct a comprehensive transcriptional regulatory network of Homo sapiens consisting of experimentally verified regulatory information on miRNAs, TFs and their target genes. We have performed topological analyses to elucidate the transcriptional regulatory roles of miRNAs and TFs. When we thoroughly investigated the network motifs, different gene regulatory scenarios were observed; whereas, mutual TF-miRNA regulation (interactive cooperation) and hierarchical operation where miRNAs were the upstream regulators of TFs came into prominence. Otherwise, biological process specific subnetworks were also constructed and integration of gene and miRNA expression data on ovarian cancer was achieved as a case study to observe dynamic patterns of the gene expression. Meanwhile, both co-operation and hierarchical operation types were determined in active ovarian cancer and process-specific subnetworks. In addition, the analysis showed that multiple signals from miRNAs were integrated by TFs. Our results demonstrate new insights on the architecture of the human transcriptional regulatory network, and here we present some lessons we gained from deciphering the reciprocal interplay between miRNAs, TFs and their target genes.

Prostaglandin E2 and vascular endothelial growth factor A mediate angiogenesis of human ovarian follicular endothelial cells

STUDY QUESTION

Which receptors for prostaglandin E2 (PGE2) and vascular endothelial growth factor A (VEGFA) mediate angiogenesis in the human follicle around the time of ovulation?

SUMMARY ANSWER

PGE2 and VEGFA act via multiple PGE2 receptors (PTGERs) and VEGF receptors (VEGFRs) to play complementary roles in follicular angiogenesis.

WHAT IS KNOWN ALREADY

Production of PGE2 and VEGFA by the follicle are prerequisites for ovulation. PGE2 is an emerging regulator of angiogenesis and has not been examined in the context of the human ovulatory follicle. VEGFA is an established regulator of follicular angiogenesis.

STUDY DESIGN, SIZE, DURATION

Ovarian biopsies containing the ovulatory follicle were obtained from 11 women of reproductive age (30-45 years) undergoing surgery for laparoscopic sterilization. In some cases, women received hCG to substitute for the ovulatory LH surge before ovarian biopsy. In addition, aspirates from four women of reproductive age (18-31 years) undergoing gonadotrophin stimulation for oocyte donation were obtained for isolation of human ovarian microvascular endothelial cells (hOMECs).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Ovarian biopsies were utilized for immunocytochemical detection of von Willebrand factor to identify endothelial cells. hOMECs were cultured with PGE2, PTGER receptor selective agonists, VEGFA, or VEGFR selective agonists. hOMECs were assessed for proliferation by Ki67 immunocytochemistry. hOMEC migration was determined by counting cells which migrated through a porous membrane in vitro. Sprout formation was quantified by determining sprout number and length from photographs take after culture of hOMECs in a 3-dimensional matrix.

MAIN RESULTS AND THE ROLE OF CHANCE

Endothelial cells were not observed within the granulosa cell layer of human ovulatory follicles prior to an ovulatory dose of hCG and were first seen amongst granulosa cells 18-34 h after hCG. In vitro, PGE2 enhanced migration and sprout formation but did not alter hOMEC proliferation. Agonists selective for each PTGER increased migration with no change in proliferation. PTGER1 and PTGER2 agonists increased the number of sprouts, while only PTGER1 affected sprout length. VEGFA increased hOMEC proliferation, migration, and formation of structures resembling capillary sprouts. Signaling through VEGFR1 promoted hOMEC migration, proliferation, and the formation of few, long endothelial cell sprouts, while VEGFR2 stimulation promoted hOMEC migration and the formation of many, short sprouts. All effects of treatments in vitro were considered significant at P < 0.05.

LIMITATIONS, REASONS FOR CAUTION

While primary cultures of hOMECs respond to PGE2 and VEGFA differently than other cultured endothelial cells, hOMECs may not respond to PGE2 and VEGFA in vivo as they do in vitro.

WIDER IMPLICATIONS OF THE FINDINGS

Agonists and antagonists selective for PTGER1, PTGER2, VEGFR1, or VEGFR2 may have therapeutic value to promote or prevent ovulation in women.

STUDY FUNDING/COMPETING INTERESTS

This research was supported by grant funding from the Eunice Kennedy Shriver National Institutes of Child Health and Human Development (HD071875 to D.M.D., T.E.C., M.B.). The authors have no conflicts of interest to disclose.

Follicular fluid placental growth factor is increased in polycystic ovarian syndrome: correlation with ovarian stimulation

BACKGROUND

Polycystic ovarian syndrome (PCOS) is characterized by increased ovarian angiogenesis and vascularity. Accumulating evidence indicates that vascular endothelial growth factor (VEGF) is increased in PCOS and may play an important role in these vascular changes and the pathogenesis of this disease. Placental growth factor (PlGF), a VEGF family member, has not been previously characterized in PCOS women. We investigated levels and temporal expression patterns of PlGF and its soluble receptor sFlt-1 (soluble Fms-like tyrosine kinase) in serum and follicular fluid (FF) of women with PCOS during controlled ovarian stimulation.

METHODS

This was a prospective cohort study of 14 PCOS women (Rotterdam criteria) and 14 matched controls undergoing controlled ovarian stimulation. Serum was collected on day 3, day of hCG and day of oocyte retrieval. FF was collected on retrieval day. PlGF, sFlt-1 and anti-mullerian hormone (AMH) protein concentrations were measured using ELISA. Since sFlt-1 binds free PlGF, preventing its signal transduction, we calculated PlGF bioavailability as PlGF/sFlt-1 ratio.

RESULTS

Serum PlGF and sFlt-1 levels were constant throughout controlled ovarian stimulation, and no significant differences were observed in either factor in PCOS women compared with non-PCOS controls at all three measured time points. However, FF PlGF levels were increased 1.5-fold in PCOS women compared with controls (p < 0.01). Moreover, FF PlGF correlated positively with number of oocytes retrieved and the ovarian reserve marker anti-mullerian hormone (AMH) and negatively with age. In addition, FF sFlt-1 levels were decreased 1.4-fold in PCOS women compared to controls (p = 0.04). PlGF bioavailability in FF was significantly greater (2-fold) in PCOS women compared with non-PCOS controls (p < 0.01).

CONCLUSIONS

These data provide evidence that FF PlGF correlates with ovarian stimulation and that its bioavailability is increased in women with PCOS undergoing controlled ovarian stimulation. This suggests that PlGF may play a role in PCOS pathogenesis and its angiogenic dysregulation.

Effect of antiprogesterone RU486 on VEGF expression and blood vessel remodeling on ovarian follicles before ovulation

Background

The success of ovarian follicle growth and ovulation is strictly related to the development of an adequate blood vessel network required to sustain the proliferative and endocrine functions of the follicular cells. Even if the Vascular Endothelial Growth Factor (VEGF) drives angiogenesis before ovulation, the local role exerted by Progesterone (P₄) remains to be clarified, in particular when its concentration rapidly increases before ovulation.

Aim

This in vivo study was designed to clarify the effect promoted by a P₄ receptor antagonist, RU486, on VEGF expression and follicular angiogenesis before ovulation, in particular, during the transition from pre to periovulatory follicles induced by human Chorionic Gonadotropins (hCG) administration.

Material and Methods

Preovulatory follicle growth and ovulation were pharmacologically induced in prepubertal gilts by combining equine Chorionic Gonadotropins (eCG) and hCG used in the presence or absence of RU486. The effects on VEGF expression were analyzed using biochemical and immunohistochemical studies, either on granulosa or on theca layers of follicles isolated few hours before ovulation. This angiogenic factor was also correlated to follicular morphology and to blood vessels architecture.

Results and Conclusions

VEGF production, blood vessel network and follicle remodeling were impaired by RU486 treatment, even if the cause-effect correlation remains to be clarified. The P₄ antagonist strongly down-regulated theca VEGF expression, thus, preventing most of the angiogenic follicle response induced by hCG. RU486-treated follicles displayed a reduced vascular area, a lower rate of endothelial cell proliferation and a reduced recruitment of perivascular mural cells. These data provide important insights on the biological role of RU486 and, indirectly, on steroid hormones during periovulatory follicular phase. In addition, an in vivo model is proposed to evaluate how periovulatory follicular angiogenesis may affect the functionality of the corpus luteum (CL) and the success of pregnancy.

Ovarian reserve and subsequent assisted reproduction outcomes after methotrexate therapy for ectopic pregnancy or pregnancy of unknown location

OBJECTIVE

To assess ovarian reserve after methotrexate treatment for ectopic pregnancy or pregnancy of unknown location after assisted reproductive technology (ART).

DESIGN

Retrospective cohort study.

SETTING

Large ART practice.

PATIENT(S)

Women receiving methotrexate or surgery after ART.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Follicle-stimulating hormone (FSH), antral follicle count (AFC), and oocyte yield compared between women treated with methotrexate or surgery, with secondary outcomes of clinical pregnancy and live birth.

RESULT(S)

There were 153 patients in the methotrexate group and 36 patients in the surgery group. Neither group demonstrated differences in ovarian reserve or oocyte yield in a comparison of the before and after treatment values. The change in ovarian reserve and oocyte yield after treatment were similar between the two groups. The number of doses of methotrexate was not correlated with changes in ovarian reserve, indicating no dose-dependent effect. Time between treatment and repeat ART was not correlated with outcomes. Live birth in subsequent cycles was similar in the two groups.

CONCLUSION(S)

Ovarian reserve and subsequent ART cycle outcomes were reassuring after methotrexate or surgical management of ectopic pregnancy. No adverse impact of methotrexate was detected in this large fertility cohort as has been previously described elsewhere.

Targeting angiogenesis in the pathological ovary

The ovary is a key tissue in the study of physiological neo-vascularisation in the adult and its study has highlighted important molecules involved in the regulation of angiogenesis in vivo. These include vascular endothelial growth factor, delta-like ligand 4, thrombospondin-1, prokineticin-1 and prostaglandin E2. Targeting these molecular pathways has therapeutic potential and their manipulation has an increasing preclinical and clinical role in the management of the pathological ovary. Targeting angiogenic pathways has utility in the promotion of ovarian angiogenesis to improve tissue and follicle survival and function as well as the prevention and management of ovarian hyperstimulation syndrome. There is a theoretical possibility that targeting angiogenesis may improve the function of the polycystic ovary and a real role for targeting angiogenesis in ovarian cancer.

Contribution of hypoxia-inducible factor-1α to transcriptional regulation of vascular endothelial growth factor in bovine developing luteal cells

Vascular endothelial growth factor (VEGF)-dependent angiogenesis is crucial for corpus leteum formation and their functional maintenance in mammalian ovaries. The present study was designed to test the hypothesis that hypoxia-inducible factor (HIF)-1α-mediated transcriptional activation contributes to the increased expression of VEGF gene in response to hypoxia in the bovine developing luteal cells (LCs). By real-time RT-PCR analysis, VEGF messenger RNA (mRNA) expression was found to significantly increase under hypoxia or treatment with desferrioxamine (DFX), cobalt chloride (CoCl(2)) or even N-carbobenzoxyl-L-leucinyl-L-leucinyl-L-norvalinal (MG-132), while these increased VEGF mRNA expressions could also be blocked by ferrous ammonium sulfate (FAS) or cis-element oligodeoxynucleotide (dsODN) transfection under hypoxia. Further analysis also found that these changes of VEGF mRNA were consistent with HIF-1α expression or HIF-1 activity. Taken together, our results indicate that VEGF is transcriptionally activated by hypoxia through HIF-1α-mediated mechanisms in LCs. This hypoxia-induced transcriptional activation may be one of the important mechanisms mediating the increase of VEGF expression in developing LCs during mammalian corpus leteum formation.

Temporal relationships of the LH surge and ovulation to echotexture and power Doppler signals of blood flow in the wall of the preovulatory follicle in heifers

Changes in echotexture and blood flow in the wall of preovulatory follicles in heifers were studied in relation to the LH surge and ovulation in gonadotrophin-releasing hormone-induced (n = 7; Experiment 1) and spontaneous (n = 8; Experiment 2) ovulators. Ultrasonographic examinations and blood sampling were performed either every hour (Experiment 1) or every 6 h (Experiment 2). The interval from LH peak to ovulation in induced and spontaneous ovulators was 27.1 ± 0.3 and 34.5 ± 1.5 h, respectively. Follicle diameter did not increase between the LH peak and ovulation. In the induced ovulators, serration of the stratum granulosum was detected in one (14%), two (29%), three (43%) and four (57%) heifers at 4, 3, 2 and 1 h before ovulation, respectively. An initial increase in blood flow (P < 0.001) encompassed the LH peak in both experiments. In the induced ovulators, blood flow increased (P < 0.02) to maximum 3 h after the LH peak, maintained a plateau for 5 h, decreased (P < 0.05) between 9 and 14 h, increased (P < 0.05) again between 19 and 21 h and then decreased (P < 0.01) between 25 and 26 h (1 h before ovulation). The biphasic increase and decrease in blood flow and serration of the granulosum in the wall of the preovulatory follicle in cattle are novel findings.

Metabolic programming of ovarian angiogenesis and folliculogenesis by maternal malnutrition during lactation

OBJECTIVE

To evaluate whether maternal malnutrition during lactation programs ovarian folliculogenesis and the expression of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) and its receptors KDR, Flt-1, and FGFR.

DESIGN

Experimental study.

SETTING

University-based research laboratory.

ANIMAL(S)

Adult female rats from a urogenital research laboratory.

INTERVENTION(S)

Six rat dams randomly assigned to the following groups: control group (C), with free access to a standard laboratory diet containing 23% protein; and a protein-energy-restricted group (PER), with free access to an isoenergy and protein-restricted diet containing 8% protein. After weaning, the female pups had free access to the standard laboratory diet until 90 days of age, when they were sacrificed at the proestrum stage.

MAIN OUTCOME MEASURE(S)

Quantification of ovarian follicles, vessels, and expression of growth factors and their receptors.

RESULT(S)

Maternal malnutrition during lactation caused a significant reduction in the number of primordial (C = 6.60 +/- 0.24, PER = 5.20 +/- 0.20), primary (C = 5.80 +/- 0.66, PER = 4.00 +/- 0.31), and Graafian follicles/section (C = 2.18 +/- 0.29, PER = 1.08 +/- 0.37), in KDR (C = 0.22 +/- 0.04, PER = 0.09 +/- 0.01), Flt-1 (C = 0.28 +/- 0.05, PER = 0.12 +/- 0.02), and FGFR mRNA expression (C = 0.34 +/- 0.05, PER = 0.13 +/- 0.05) and in the vessel density of follicles (C = 17.26 +/- 2.30, PER = 9.96 +/- 0.97).

CONCLUSION(S)

Maternal malnutrition during lactation programs the follicular development by a reduction of VEGF and FGF mRNA receptors expression, probably from a direct action on the follicular development or a reduction in vasculature resulting in a decreased delivery of folliculotrophic substances in PER animals.

The effect of follicular fluid hormones on oocyte recovery after ovarian stimulation: FSH level predicts oocyte recovery

BACKGROUND

Ovarian stimulation for assisted reproductive technology (ART) overcomes the physiologic process to develop a single dominant follicle. However, following stimulation, egg recovery rates are not 100%. The objective of this study is to determine if the follicular fluid hormonal environment is associated with oocyte recovery.

METHODS

This is a prospective study involving patients undergoing ART by standard ovarian stimulation protocols at an urban academic medical center. A total of 143 follicular fluid aspirates were collected from 80 patients. Concentrations of FSH, hCG, estradiol, progesterone, testosterone and prolactin were determined. A multivariable regression analysis was used to investigate the relationship between the follicular fluid hormones and oocyte recovery.

RESULTS

Intrafollicular FSH was significantly associated with oocyte recovery after adjustment for hCG (Adjusted odds ratio (AOR) = 1.21, 95%CI 1.03-1.42). The hCG concentration alone, in the range tested, did not impact the odds of oocyte recovery (AOR = 0.99, 95%CI 0.93-1.07). Estradiol was significantly associated with oocyte recovery (AOR = 0.98, 95% CI 0.96-0.99). After adjustment for progesterone, the strength of association between FSH and oocyte recovery increased (AOR = 1.84, 95%CI 1.45-2.34).

CONCLUSION

The relationship between FSH and oocyte recovery is significant and appears to work through mechanisms independent of the sex hormones. FSH may be important for the physiologic event of separation of the cumulus-oocyte complex from the follicle wall, thereby influencing oocyte recovery. Current methods for inducing the final stages of oocyte maturation, with hCG administration alone, may not be optimal. Modifications of treatment protocols utilizing additional FSH may enhance oocyte recovery.

Epidermal growth factor-like growth factors in the follicular fluid: role in oocyte development and maturation

The growth and maturation of the ovarian follicle requires the coordinate function of somatic cells and the oocyte. Over the past three decades, numerous growth factors involved in the bidirectional signals between the somatic and germ cells have been identified. A possible function of epidermal growth factor (EGF) signaling at selected stages of follicle maturation had been proposed early on and is supported by many observations of in vitro effects of this growth factor on steroidogenesis, oocyte maturation, and cumulus expansion. However, attempts to link EGF levels in the follicular fluid with the state of follicle and oocyte maturation have been inconclusive. More recently, data generated using mouse genetic models perturbing ovulation and fertility indicate that EGF-like growth factors, rather than EGF itself, accumulate in the follicle at the time of ovulation. EGF-like growth factor mRNA is regulated by the luteinizing hormone surge, and corresponding proteins are detected in the follicle. The EGF-like growth factors amphiregulin, epiregulin, and betacellulin are potent stimulators of oocyte maturation and cumulus expansion, and perturbation of this EGF network in vivo impairs ovulation. Similar findings in species other than the mouse confirm an important physiological role for this network at the time of ovulation. Whether this network also plays a critical role in humans and whether it can be used as a biological marker of follicle development or for the improvement of fertility remains to be determined. This review summarizes the most recent findings on the EGF network during ovulation and the potential clinical applications of manipulating this intercellular communication pathway in the control of fertility.