Vascular endothelial growth factor A improves quality of matured porcine oocytes and developing parthenotes

Proximity extension assay revealed novel inflammatory biomarkers for follicular development and ovarian function: a prospective controlled study combining serum and follicular fluid

Background

Many components in follicular fluid (FF), such as peptide hormones, cytokines, and steroids, undergo dynamic changes during folliculogenesis and have important roles in follicular development. Because systemic inflammation has also been found to contribute to diminished ovarian reserve (DOR) in previous studies, do certain serum/FF inflammatory biomarkers affect both follicular development and ovarian function?

Methods

Serum samples from the menstruation phase (n=26), serum samples from the ovulation phase (n=26), FF samples of mature oocytes (n=26), and FF samples of immature oocytes (n=10) were collected. Olink proteomic proximity extension assay (PEA) technology was used to compare the differentially expressed proteins (DEPs), and patients were divided into two subgroups-the normal ovarian reserve (NOR) group and the DOR group-for further bioinformatics analysis and verification by enzyme-linked immunosorbent assay (ELISA).

Results

In total, 16 DEPs were detected between the mature group and the immature group (FF), and 11 DEPs were detected between the ovulation group and the menstruation group (serum). Further subdivision of the ovarian reserve subgroups revealed 22 DEPs in FF and 3 DEPs in serum. Among all four comparisons, only the expression of oncostatin M (OSM) significantly differed. The OSM signaling pathway, the IL-10 anti-inflammatory signaling pathway, and the PI3K-Akt signaling pathway are three notable pathways involved in affecting ovarian reserve capacity according to bioinformatics analysis. In addition, the concentration of estradiol on the hCG day was slightly but positively correlated with OSM (r=0.457, P=0.029). A significantly greater level of OSM (5.41 ± 2.65 vs. 3.94 ± 1.23 pg/mL, P=0.007) was detected in the serum of NOR patients via ELISA verification, and the sensitivity and specificity of ovarian reserve division were 50.00% and 83.33%, respectively.

Conclusion

This study proposed that immunological changes assessed by PEA technology affect ovarian function in humans and that OSM may serve as a potential inflammatory biomarker for ovarian function in serum, thus revealing alterations in FF.

Low oxygen concentration improves yak oocyte maturation and inhibits apoptosis through HIF-1 and VEGF

The gas-phase environment of in vitro culture system plays an important role in the development of oocytes, and oxygen concentration is one of the important factors. In the present study, we aimed to explore the effect of different oxygen concentrations (20%, 10%, 5% or 1% O₂ ) in yak oocyte maturation and to detect the expression of HIF-1α, VEGF and cell apoptosis in yak COCs. First, the maturation rate of oocytes, cleavage rate and blastocysts rate following parthenogenetic activation in the group with 5% oxygen concentration were significantly higher (p < 0.05) than the other groups. Then, TUNEL analysis showed that the 5% oxygen concentration group significantly inhibited apoptosis of cumulus-oocyte complexes (COCs) compared to the other group, and the transcription and protein levels of pro-apoptotic factor Bax, HIF-1α and VEGF in yak COCs significantly reduced, while anti-apoptotic factor Bcl-2 significantly increased. Furthermore, immunohistochemical staining results indicated that HIF-1α protein was mainly located in theca follicle interna, mural follicular stratum granulosum, corona radiata and ovarian stroma in the follicular ovarian tissue; while VEGF protein was mainly located in the granulosa and theca cell layers. In summary, our findings demonstrate that 5% oxygen concentration may promote maturation and inhibit apoptosis of oocytes through HIF-1α-mediated VEGF expression.

Maternal Cytokines CXCL12, VEGFA, and WNT5A Promote Porcine Oocyte Maturation via MAPK Activation and Canonical WNT Inhibition

Maternal regulatory factors endow the oocyte with developmental competence in vivo, which might be absent in current in vitro maturation (IVM) systems, thereby compromising oocyte quality. In the present study, by employing RNA sequencing data analysis, we expect to identify potential contributing factors to support porcine oocyte maturation through binding to their receptors on the oolemma. Here, C-X-C motif chemokine ligand 12 (CXCL12), vascular endothelial growth factor A (VEGFA), and Wingless-type MMTV integration site family member 5A (WNT5A), termed CVW, are selected and confirmed to be important maternal cytokines for porcine oocyte maturation. Combined supplementation of CVW promotes the nuclear maturation percentage from 57.2% in controls to 75.9%. More importantly, these maternal cytokines improve the developmental potential of matured oocytes by parthenogenesis, fertilization, and cloning, as their blastocyst formation efficiencies and total cell numbers are increased. CVW supplementation also enlarges perivitelline space and promotes cumulus expansion, which results in a more complete transzonal projection retraction on the zona pellucida, and a reduced incidence of polyspermy in fertilized oocytes. Meanwhile, inhibiting the CVW receptor-mediated signaling pathways severely impairs oocyte meiotic resumption and cumulus expansion during IVM. We further determine that maturation improvement by CVW is achieved through activating the MAPK pathway in advance and inhibiting the canonical WNT pathway at the end of the IVM period. These findings provide a new combination of three cytokines to promote the porcine IVM process, which also holds potential to be used in human assisted reproduction technologies as well as in other species.

Ultrastructural Characterization of Porcine Growing and In Vitro Matured Oocytes

Simple Summary

During oocyte growth and maturation, the organelle’s morphology of porcine oocytes changed and populated different compartments depending on the differentiation status. Changes in ultrastructural or subcellular level of porcine oocytes during oogenesis/folliculogenesis were observed, potentially leading to future mitochondrion replacement therapies of oocytes.

Abstract

This study aimed to investigate ultrastructural changes of growing porcine oocytes and in vitro maturated oocytes. Light microscopy was used to characterize and localize the primordial, primary, secondary, and tertiary follicles. During oocyte growth and maturation, the morphology of mitochondria was roundish or ovoid in shape depending on the differentiation state, whereas their mean diameters oscillated between 0.5 and 0.7 µm, respectively, from primary and secondary follicles. Hooded mitochondria were found in the growing oocytes of the tertiary follicles. In addition to the pleomorphism of mitochondria, changes in the appearance of lipid droplets were also observed, along with the alignment of a single layer of cortical granules beneath the oolemma. In conclusion, our study is apparently the first report to portray morphological alterations of mitochondria that possess the hooded structure during the growth phase of porcine oocytes. The spatiotemporal and intrinsic changes during oogenesis/folliculogenesis are phenomena at the ultrastructural or subcellular level of porcine oocytes, highlighting an in-depth understanding of oocyte biology and impetus for future studies on practical mitochondrion replacement therapies for oocytes.

Genes expression and phenotypic differences in corpus luteum and cumulus cells of commercial line and piau breed gilts

We aimed to characterize the expression of angiogenesis-related genes in corpus luteum (CL) and cumulus cells (CC) during estrous cycle in gilts of different genetic groups, as well as to study the relation between gene expression and phenotypic data. Forty five gilts were used as follows: L1, Commercial Line 1 (Large White x Landrace x Duroc) (n = 15); L2, Commercial Line 2 (Large White x Landrace x Pietrain) (n = 15); and Piau, Piau breed gilts (n = 15). Estrus observation started from 120 days of age. After the second observed estrus females were slaughtered (n = 3) on days 3, 5, 10, 14 and 18 of estrous cycle (first day of estrous cycle as Day 0). CL sampling was performed on days 3, 5, 10 and 14 and collection of CC and follicular fluid on days 14 and 18. Follicular fluid was used for analysis of estradiol levels and CC and CL samples for analysis of angiogenesis-related genes expression, ANGPT-1/-2 and TEK in CC and MMP-2, VEGFA, VEGFR-1/-2, ANGPT-1/-2 and TEK in CL. Piau gilts showed lower ovulation rate than both L1 and L2 gilts (P < 0.05), lower number of large antral follicles (>6 mm) at 18 days than L2 gilts (P < 0.05), and smaller diameter of the largest follicles at 14 days than L1 gilts (P < 0.05). Piau and L2 gilts showed higher estradiol levels in follicular fluid on day 18. Expression of ANGPT-1 and -2 genes in CC did not differ among genetic groups neither among days of the estrous cycle, but TEK gene expression was higher in L1 than L2 gilts on day 18. Expression of VEGFA, VEGFR-2 and MMP-2 genes in CL did not differ among genetic groups and days of cycle, but VEGFR-1 expression was higher in Piau than L2 gilts on days 10 and 14, and it was higher in L1 than L2 gilts on day 14. The ANGPT-1/-2 and TEK genes expression in CL were significantly higher in Piau than L1 gilts on day 10. The ANGPT-2/ANGPT-1 gene expression ratio in CL was higher in L1 than Piau and L2 gilts at 14 days, suggesting a shorter luteal phase for L1 gilts. Results indicated differences among genetic groups for the pattern of the angiogenesis-related genes expression in CL along estrous cycles, which may be reflected in phenotypic traits such as ovulation rate, estradiol levels in follicular fluid and number and diameter of antral follicles.

Vascular Endothelial Growth Factor Enhances Compensatory Lung Growth in Piglets

BACKGROUND

Vascular endothelial growth factor has been found to accelerate compensatory lung growth after left pneumonectomy in mice. The aim of this study was to determine the natural history and the effects of vascular endothelial growth factor on compensatory lung growth in a large animal model.

METHODS

To determine the natural history of compensatory lung growth, female Yorkshire piglets underwent a left pneumonectomy on days of life 10-11. Tissue harvest and volume measurement of the right lung were performed at baseline (n = 5) and on postoperative days 7 (n = 5), 14 (n = 4), and 21 (n = 5). For pharmacokinetic studies, vascular endothelial growth factor was infused via a central venous catheter, with plasma vascular endothelial growth factor levels measured at various time points. To test the effect of vascular endothelial growth factor on compensatory lung growth, 26 female Yorkshire piglets underwent a left pneumonectomy followed by daily infusion of vascular endothelial growth factor at 200 µg/kg or isovolumetric 0.9% NaCl (saline control). Lungs were harvested on postoperative day 7 for volume measurement and morphometric analyses.

RESULTS

Compared with baseline, right lung volume after left pneumonectomy increased by factors of 2.1 ± 0.6, 3.3 ± 0.6, and 3.6 ± 0.4 on postoperative days 7, 14, and 21, respectively. The half-life of VEGF ranged from 89 to 144 minutes. Lesser doses of vascular endothelial growth factor resulted in better tolerance, volume of distribution, and clearance. Compared with the control group, piglets treated with vascular endothelial growth factor had greater lung volume (P < 0.0001), alveolar volume (P = 0.001), septal surface area (P = 0.007) and total alveolar count (P = 0.01).

CONCLUSION

Vascular endothelial growth factor enhanced alveolar growth in neonatal piglets after unilateral pneumonectomy.

Embryotropic effects of vascular endothelial growth factor on porcine embryos produced by in vitro fertilization

Current research suggests that supplementing in vitro culture (IVC) media with vascular endothelial growth factor (VEGF) may have beneficial effects on the development of porcine embryos in vitro. However, the molecular signaling mechanisms underlying this effect are unclear. Therefore, we aimed to investigate the effects of VEGF on molecular signaling events during in vitro embryonic development of porcine embryos. Porcine oocytes matured in vitro were fertilized, and the resultant zygotes were cultured with 5 ng/mL of VEGF supplemented with or without fetal bovine serum from day 4 till day 7. Without VEGF and/or FBS served as the control group. Real-time quantitative PCR was used to detect expression patterns of apoptosis- and oxidative stress-related genes in day 7 blastocysts (BLs). Early-stage apoptosis was detected by annexin-V assays in day 2 and day 7 embryos. We found that the addition of VEGF throughout the culture period with or without FBS supplementation significantly improved embryo survival and development. Supplementation with VEGF in the IVC medium significantly increased early BL formation (p < 0.05), although addition of FBS on day 4 significantly increased hatched BL formation (p < 0.05) regardless of VEGF supplementation. However, supplementation of media with both VEGF and FBS increased the formation of expanded BLs synergistically. The average total cell numbers per BL were significantly (p < 0.05) higher in embryos supplemented with VEGF and FBS than in those supplemented with either VEGF or FBS alone. We also found that accumulation of reactive oxygen species in VEGF-treated embryos was significantly lower (p < 0.05) than that in untreated embryos. The mRNA levels of caspase-3 were significantly lower (p < 0.05), and those of Bcl-2 and Nrf-2 were significantly higher (p < 0.05) in embryos grown in VEGF-supplemented media than in embryos grown in non-supplemented media. Furthermore, on day 2, the numbers of viable embryos (44.06 ± 3.94%) and blastomeres (67.18 ± 3.60%) were significantly higher (p < 0.05), and the numbers of early apoptotic embryos (55.94 ± 3.94) and blastomeres (23.23 ± 4.22) were significantly lower (p < 0.05) in VEGF-treated BLs than in controls. Furthermore, the numbers of early apoptotic cells in BLs on day 7 were also significantly lower (p < 0.05) in VEGF-treated BLs than in controls. Overall, our results indicate that supplementing IVC media with VEGF during in vitro culture of porcine embryos increases their developmental potential.

Presence of vascular endothelial growth factor during the first half of IVM improves the meiotic and developmental competence of porcine oocytes from small follicles

The aim of the present study was to investigate the effect of vascular endothelial growth factor (VEGF) on the meiotic and developmental competence of porcine oocytes from small follicles (SF; 0.5-3mm diameter). When cumulus-oocyte complexes (COCs) from medium-sized follicles (MF; 3-6mm diameter) and SF were cultured for IVM, the maturation rates were significantly higher for oocytes from MF than SF. Concentrations of VEGF in the medium were significantly higher for COCs cultured from MF than SF. When COCs from SF were exposed to 200ngmL^-1 VEGF during the first 20h of IVM, the maturation rate improved significantly and was similar to that of oocytes derived from MF. The fertilisability of oocytes was also significantly higher than that of VEGF-free SF controls. Following parthenogenetic activation, the blastocyst formation rate improved significantly when SF COC culture was supplemented with 200ngmL^-1 VEGF, with the rate similar to that of oocytes from MF. The results of the present study indicate that VEGF markedly improves the meiotic and developmental competence of oocytes derived from SF, especially at a concentration of 200ngmL^-1 during the first 20h of IVM.

The effects of activated omental extract on nuclear and cytoplasmic in vitro maturation of rat oocytes

Objective:

The role of growth factors, including vascular endothelial growth factor of activated omentum on mitosis is clearly known, though not on all the aspects of in vitro oocyte maturation. This study was designed to assess the effect of activated-omental extract (AOE) on in vitro maturation (IVM) of rat cumulus-oocyte complexes (COCs).

Materials and Methods:

In this experimental study, the COCs were incubated in Ham’s F-10 supplemented with either 20% AOE, 20% fetal bovine serum (FBS) or serum-free media. Post-culture COCs were studied according to the cumulus cells (CCs) expansion, nuclear maturation and cytoplasmic maturation. Cumuli expansion was evaluated by inverted microscope without staining; nuclear maturation was assessed by aceto-orcein staining (light microscope) and cytoplasmic maturation was also observed by TEM.

Results:

Expansion of CCs and nuclear maturation of the oocytes in in vitro for 24 hr was significantly higher in AOE- and FBS-supplemented groups (P=0.000 and 0.013) and (P=0.004 and 0.014), respectively, compared to serum-free group. At ultra-structural level, after 24 hr, both FBS and AOE-supplemented media showed uniformly wide perivitelline space (PVS). After 12 hr, the cortical granules were found in the oocytes cultured in FBS and AOE-supplemented media. Within 24 hr, both granules and mitochondria were large without any detectable topographic tendency across the ooplasm. In AOE and FBS-supplemented oocytes, the number and size of microvilli were more than those in serum-free one.

Conclusion:

Although AOE supplementation induced a higher rate of the CCs expansion, and resuming meiosis, it was not as potent as FBS to provide cytoplasmic maturation of rat oocytes.

Supplementation with cumulus cell masses improves the in vitro meiotic competence of porcine cumulus-oocytes complexes derived from small follicles

The present study was conducted to examine the supplemented effect of cumulus cell masses (CCMs) derived from middle follicle (MF; 3-6 mm diameter) on the morphology and the meiotic or developmental competence of oocytes from small follicles (SF; 1-2 mm diameter). The number of cumulus cells surrounding oocytes just after collection was also lower in cumulus-oocyte complexes (COCs) from SF than MF. The ooplasmic diameter of oocytes was significantly smaller in SF-derived oocytes than MF-derived ones before and after in vitro maturation (IVM), whereas the diameter significantly increased during the culture. Co-culture of SF-derived COCs with MF-derived CCMs during IVM significantly improved the meiotic competence of the oocytes to the metaphase-II stage. Furthermore, the ooplasmic diameter of SF-derived COCs during IVM was increased to the similar size of MF-derived those in the presence of MF-derived CCMs. The abilities of oocytes to be penetrated, to form male pronuclear formation and to cleave or develop to the blastocyst stage were not affected by the co-culture with CCMs. Electrophoretic analysis of CCM secretions clearly showed the presence of more protein(s) approximately 27.6 kDa in the conditioned medium when supplemented with MF-derived CCMs. In conclusion, we demonstrate that supplementation with MF-derived CCMs improves the ooplasmic diameter and meiotic competence of SF-derived oocytes.

Optimal FSH usage in revascularization of allotransplanted ovarian tissue in mice

Backgroud

Ovarian transplantation is a useful method for preserving the fertility of young women with cancer who undergo radiotherapy and chemotherapy. Follicle-stimulating hormone (FSH) is use to protect transplanted ovarian tissues from ischemia injury through promoting revascularization after transplantation, but the side effect of high level FSH is ovarian overstimulation leading to substantial follicular loss. In this study, we investigated the optimal usage of FSH on revascularization in the in vitro cultured ovarian tissues before and after transplantation.

Results

FSH mainly exhibited an additive response in the gene and protein expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and follicle stimulating hormone receptor (FSHR) with its raised concentrations (0.15 IU/ml, 0.30 IU/ml and 0.60 IU/ml) and prolonged treatment (3 h, 6 h, 12 h, 24 h). The concentrations with 0.60 IU/ml FSH could obviously promoted the expression of VEGF, bFGF and FSHR, but under this concentration FSH could also overstimulated the ovarian tissue leading to follicular loss. With the increase of culture time, the gene and protein expression of VEGF and bFGF both were up-regulated in all of the FSH added groups, but FSHR expression decreased when culture time exceeded 12 h. So we chose 0.30 IU/ml FSH added concentration and 6 h culture time as the FSH usage condition in functional revascularization verification experiment, and found that under this condition FSH promoted 2.5 times increase of vascular density in treated group than in control group after ovarian tissues transplantation.

Conclusion

Ovarian intervention with 0.30 IU/ml FSH for 6 h is an optimal FSH usage condition which could accelerate the revascularization in the allotransplanted ovarian tissue and can not produce ovarian overstimulation.

Identificação imuno-histoquímica de VEGF e IGF-1 em ovários de cadelas no anestro e estro

Com o objetivo de verificar a presença de VEGF e IGF-1 nos ovários de cadelas, foram realizadas análises imuno-histoquímicas do estroma cortical; teca e granulosa de folículos secundários, terciários e terciários pré-ovulatórios luteinizados; e ovócitos de folículos primários, secundários e terciários de ovários de cinco cadelas em anestro (Anest) e cinco em estro (Est). A identificação das fases do ciclo estral foi realizada por citologia vaginal associada a dosagem plasmática de progesterona. Os ovários foram submetidos a tratamento imuno-histoquímico para identificação de VEGF (anticorpo primário PU 360-UP, Biogenex, USA; diluição 1:30) e IGF-1 (anticorpo primário PabCa, Gro-Pep, Austrália; diluição 1:100). Determinou-se um índice de imunomarcação (IM), para cada tecido avaliado, pela razão entre a área positivamente marcada dividida pela área total analisada. Para os ovócitos, verificou-se imunomarcação positiva ou negativa. As comparações de IM entre tecidos foram realizadas pelo teste de Wilcoxon (diferentes tecidos em mesmo grupo) ou Mann-Whitney (mesmo tecido entre diferentes grupos), todas no nível de 5% de significância. VEGF e IGF-1 foram identificados, de forma semelhante (P>0,05), em todas as estruturas avaliadas em ambos os grupos experimentais. Conclui-se que esses fatores de crescimento estão presentes em cadelas no anestro e estro, no estroma cortical ovariano, folículos em diferentes estádios de desenvolvimento e ovócitos.