Human Reproduction, Vol. 16, No. 4, 621-626,
April 2001
© 2001 European Society of Human Reproduction and Embryology
Poor responder–high responder: the importance of soluble vascular endothelial growth factor receptor 1 in ovarian stimulation protocols
1 Department of Gynecological Endocrinology and Reproductive Medicine, University Clinic, RWTH Aachen, 2 Ges. Biotechnologische Forschung, 3 Receptor Ligand Technologies GmbH (RELIATech), Braunschweig and 4 Department of Pathology, University Clinic, RWTH Aachen, Germany
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Abstract |
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This study was designed to detect vascular endothelial growth factor (VEGF) and its soluble receptor (sVEGFR-1) in follicular fluid specimens and to evaluate the importance of sVEGFR-1 with respect to ovarian response to gonadotrophin stimulation. A total of 69 patients was treated for IVF with recombinant human follicle stimulating hormone (FSH). Concentrations of VEGF and sVEGFR-1 were quantified in follicular fluids from oocyte retrievals. Patients were designated to three groups with respect to the number of harvested oocytes: group A, 1–5 oocytes; group B, 6–10 oocytes; group C, >10 oocytes. In group A, 1133 ± 870 pg VEGF/ml follicular fluid per oocyte were quantified, in group B 426 ± 262 pg VEGF/ml per oocyte, and in group C 274 ± 179 pg VEGF/ml per oocyte. Soluble VEGFR-1 concentrations resulted in 1200 ± 523 pg/ml follicular fluid per oocyte in group A, 255 ± 193 pg/ml per oocyte in group B, and 79 ± 69 pg/ml per oocyte in group C. No free sVEGFR-1 could be detected in any follicular fluid. An index to estimate the biological activity of VEGF by dividing VEGF/sVEGFR-1 revealed an increasing availability of VEGF with higher ovarian response to gonadotrophin therapy. In group A this index was 1.03, in group B 1.71, and in group C 3.21. A delicate balance between VEGF and sVEGFR-1 is necessary to allow an adequate ovarian reaction to gonadotrophin therapy. Excess of bio-active VEGF increases the risk for ovarian hyperstimulation syndrome. Excess of sVEGFR-1 results in poor response and goes in parallel with reduced chances for conception.
Key words: gonadotrophin therapy/ovarian function/sVEGFR-1/VEGF
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Introduction |
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Vascular endothelial growth factor (VEGF) is produced by theca interna and granulosa cells in the human ovary (Yamamoto et al., 1997
). All types of VEGF are produced by granulosa cells, predominantly VEGF-A121 and VEGF-A165 (Yan et al., 1993; Neulen et al., 1996; Laitinen et al., 1997; Otani et al., 1999). Most intense production can be observed during the peri-ovulatory phase (Kamat et al., 1995). Recent results indicate that gonadotrophins influence VEGF mRNA expression and protein production with luteinizing hormone/human chorionic gonadotrophin (LH/HCG) having a prominent effect in granulosa cells (Neulen et al., 1998). Clinically, VEGF production is linked to the pathophysiology of ovarian hyperstimulation syndrome (OHSS) (Neulen et al., 1995). Several reports show high VEGF concentrations in serum (Krasnow et al., 1996) or urine (Robertson et al., 1995) to be correlated with an increased risk of this severe iatrogenic condition. Measurements of VEGF in follicular fluids give ambiguous results regarding the indicative value of high VEGF concentrations and increased risk of OHSS (Pellicer et al., 1999). It can be assumed that differences occur due to the measurement of free or bound VEGF. One widely used commercial VEGF quantification kit obviously detects only free VEGF (Banks et al., 1998). Other reagents are not characterized.
VEGF mediates its effects through two specific receptors, fms-like tyrosine receptor-1 (flt-1 = VEGFR-1) (Shibuya et al., 1990) or kinase inserted tyrosine domain receptor (KDR = VEGFR-2) (Terman et al., 1992). VEGFR-1 is also produced as a soluble receptor (sVEGFR-1) by alternative splicing of the precursor mRNA (Kendall et al., 1996). It is not yet clear whether proteolytic shedding produces additionally sVEGFR-1. Obviously, sVEGFR-1 acts as a negative modulator for the bioactivity of VEGF (Hornig and Weich, 1999). Both receptors are produced by endothelial cells. Endothelial cells can be accepted as a prominent source of sVEGFR-1 (Hornig et al., 2000). How the production of membrane bound or soluble VEGFR-1 is regulated in endothelial cells remains to be determined.
This study was designed to detect sVEGFR-1 in follicular fluids and to evaluate the importance of sVEGFR-1 with respect to ovarian response to gonadotrophin stimulation.
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Material and methods |
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Pooled follicular fluids were obtained from 69 individual women undergoing oocyte retrieval for IVF. Reasons for infertility were tubal occlusion (36 couples), male infertility (24 couples), and unexplained infertility (nine couples). Written consent was obtained and the experimental design was approved by the local ethical committee.
In these patients, multiple follicular development was achieved with recombinant human FSH (rhFSH 150–225 IU per day, Gonal-F®; Serono, Munich, Germany) until follicular maturity. Gonadotrophin therapy was preceded by complete desensitization of the pituitary gland with 0.1 mg per day of tryptorelin (Decapeptyl®; Ferring, Kiel, Germany). For ovulation induction 5000 or 10 000 IU HCG (Pregnesin®; Serono) were injected 36 h prior to ultrasound-guided transvaginal follicle aspiration when at least two follicles reached 18 mm in diameter.
Patients were designated to three groups with respect to the number of harvested oocytes: group A (low responder; 22 patients; mean age: 34.8 ± 2.6 years): 1–5 oocytes; group B (average responder; 21 patients; mean age: 33.2 ± 4.5 years): 6–10 oocytes; group C (high responder; 26 patients; mean age: 31.6 ± 3.5 years): >10 oocytes. Mean total rhFSH dose in group A was 2270 IU/cycle, in group B 1865 IU/cycle, and in group C 1625 IU/cycle. To induce ovulation mean total dose of HCG in group A was 9545 IU, in group B 8095 IU, and in group C 8653 IU. Only pregnancies in the eighth week were counted.
After oocyte collection follicular fluids were centrifuged at 500 g to remove blood cell contaminations. Aliquots of the individually pooled follicular fluids were stored at –20°C until VEGF and sVEGFR-1 quantification.
Serum oestradiol at the day of HCG injection was quantified with an automated technique (Bayer/Chiron Diagnostics, Neuss, Germany) according to the manufacturer's recommendations.
VEGF (also described as VEGF-A) in follicular fluids was quantified with a commercially available sandwich enzyme-linked immunosorbent assay (ELISA; R&D Systems, Wiesbaden-Nordenstadt, Germany) according to the manufacturer's recommendations.
Total (free and VEGF complexed) sVEGFR-1 was quantified with sandwich ELISA technique as described previously (Hornig et al., 1999) and applied according to the manufacturer's (RELIATech, Braunschweig, Germany) specifications. The determination of free, uncomplexed sVEGFR-1 was performed as described recently (Hornig et al., 2000) by a modified ELISA (RELIATech). Undiluted follicular fluid samples were processed in duplicates.
For immunoblotting of sVEGFR-1 pooled follicular fluids with highest sVEGFR-1 concentrations were used (Hornig et al., 2000). In short, VEGFR-1 from 5 ml aliquots of follicular fluid which were adjusted to 0.5 mmol/l NaCl were concentrated by a Hitrap heparin-sepharose column (Parmacia-Biotech, Freibrug, Germany), eluted with 1.5 mmol/l NaCl, concentrated by trichloracetic acid (TCA) precipitation, and separated on sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE). After blotting, mouse monoclonal Flt-11 antibody (Sigma, Taufkirchen, Germany) was used for detection of sVEGFR-1.
Immunohistochemical stainings were performed on 5 µm cryostat sections of snap-frozen ovary tissue specimens from a premenopausal patient undergoing surgery for diagnosis of endometriosis during the follicular phase of cycle. After acetone fixation at –20°C for 10 min, sections were blocked for 15 min with 5% horse serum and incubated at 4°C with 1:200 dilution of the mouse monoclonal antibody anti-VEGF-1 (FLT-19) (Hornig et al., 1999). After washing 3x5 min with 2% non-fat dry milk dissolved in phosphate buffered saline (PBS), the sections were incubated for 30 min with 1:500 dilution of goat anti-mouse IgG-biotin labelled antiserum (DAKO, Copenhagen, Denmark) at room temperature, washed again three times and incubated for 30 min with the ABC complex (VectorLab, Burlingame, CA, USA) according to the manufacturer's instructions. To visualize immuno-complexes, the slides were finally incubated in 50 ml diaminobenzidine solution (30 mg DAB, 0.3 g Tris-Cl pH 7.6) for 2 min at room temperature and counterstained with hemalaun (Merck, Darmstadt, Germany) for 2 min (Partanen et al., 1999).
Values are indicated as mean ± SD. To determine whether there were differences at all between the three patient groups an analysis of variance (ANOVA) test was performed for oestradiol, VEGF and sVEGFR-1 results. For further statistical analysis Student's t-test was applied.
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Results |
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At the day of HCG injection, in group A oestradiol concentrations were: 2408 ± 1513 pmol/l. An average of 3.6 oocytes per patient could be harvested. Four patients became pregnant. In group B oestradiol concentrations were: 3761 ± 2573 pmol/l. An average of 8.4 oocytes per patient could be harvested. Four patients became pregnant. In group C oestradiol concentrations were: 5767 ± 3160 pmol/l (oestradiol group A versus group B: P = 0.0218; group B versus group C: P = 0.0081; group A versus group C: P < 0.0001). An average of 14.5 oocytes per patient could be harvested. Five patients became pregnant.
VEGFR-1 antibodies detected specific antigen in blood vessels throughout the ovary. Intense staining in the vicinity of follicles indicated a higher capillary network around antral follicles. No staining could be detected in theca interna or granulosa cells (Figure 1).
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Recombinant sVEGFR-1 (domain 1–5) rendered in Western blots a single band by immunoblotting at about 75kDa. Recombinant sVEGFR-1 (domain 1–6) yielded a molecular weight of 90 kDa. Follicular fluid revealed a specific staining with two distinct bands for sVEGFR-1 at a molecular weight of about 110 kDa (Figure 2
). This indicates that native human sVEGFR-1 is more intensely glycosylated than recombinant sVEGFR-1. The second band may be due to heparin leaking from the separation column (Hornig et al., 2000). The molecular weight of the naturally occurring sVEGFR-1 of 110 kDa was demonstrated by several groups, independently. This molecule was isolated from human amniotic fluid and sequenced previously (Banks et al., 1998; He et al., 1999). In the Western blot experiments of the current study, this naturally occurring sVEGFR-1 was compared with two forms of recombinant sVEGFR-1 produced in insect cells. The recombinant forms are smaller than the natural form due to less glycosylation by insect cells. Deglycosylation of natural human sVEGFR-1 and sVEGFR-1 produced by insect cells renders soluble receptors of equal size (Hornig et al., 2000).
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The mean values ± SD were quantified in group A, 4226 ± 2862 pg VEGF/ml follicular fluid, in group B 3559 ± 2417 pg/ml, and in group C 3727 ± 2076 pg/ml (differences not statistically significant). In group A this resulted in 1133 ± 870 pg VEGF/ml per oocyte, in group B in 426 ± 262 pg VEGF/ml per oocyte, and in group C in 274 ± 179 pg VEGF/ml per oocyte (Figure 3
) (differences group A versus group B: P < 0.0001; group B versus group C: P = 0.0085; group A versus group C: P < 0.0001).
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Soluble VEGFR-1 concentrations revealed a significant negative correlation with the number of harvested oocytes: group A 4110 ± 1060 pg sVEGFR-1/ml follicular fluid, group B 2080 ± 1520 pg/ml, and group C: 1160 ± 810 pg/ml (group A versus group B: P < 0.0001; group B versus group C: P = 0.0217; group A versus group C: P < 0.0001). Soluble VEGFR-1 concentrations in serum are below the detection limit of the applied assay. These values resulted in 1200 ± 523 pg sVEGFR-1/ml per oocyte in group A, 255 ± 193 pg sVEGFR-1/ml per oocyte in group B, and 79 ± 69 pg sVEGFR-1/ml per oocyte in group C (all P values < 0.0001). No free sVEGFR-1 could be detected in any follicular fluid (Figure 4
).
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An index to estimate the biological activity of VEGF by dividing VEGF/sVEGFR-1 revealed an increasing availability of VEGF with higher ovarian response to gonadotrophin therapy. In group A this index was 1.03, in group B 1.71, and in group C 3.21 (Figure 5
).
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Discussion |
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TopAbstractIntroductionMaterial and methodsResultsDiscussionAcknowledgementsReferences |
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Data presented in this study indicate that availability of biologically active VEGF is associated with the individual response to gonadotrophin therapy. A negative correlation can be assumed with the amount of sVEGFR-1 in follicular fluids. No free sVEGFR-1 was detected in follicular fluid suggesting that the intrafollicular amount reflected the capacity of sVEGFR-1 production by surrounding capillary endothelia. In contrast to previous data (Otani et al., 1999
), no production of VEGFR-1 in theca interna or granulosa cells could be demonstrated either by immunohistochemistry or by Northern blot technique (Yan et al., 1998).
Several trials were undertaken to unravel causes of low ovarian reaction to gonadotrophin therapy. There is evidence that diminished ovarian reserve might result in low response (Pellicer et al., 1998). Obviously different from these patients are women with elevated FSH concentrations reflecting a reduced inhibin production by granulosa cells. This condition is mainly observed in the perimenopausal phase (Muasher, 1992).
It is a matter of debate whether therapy regimes with high doses of FSH (>450 IU FSH/day) result in more mature follicles in low responders (Hofmann et al., 1989; Karande et al., 1990). Intravenous administration of FSH in a pulsatile manner did not improve IVF outcome in low responders (Edelstein et al., 1990).
The overall pregnancy rate in patients with low ovarian response is reduced. Therefore, IVF was ensured by intracytoplasmic sperm injection. However, no benefit from this procedure could be demonstrated (Moreno et al., 1998).
Glucocorticoid treatment for patients with low ovarian response was applied to increase the number of mature oocytes in IVF cycles. There was no improvement in any clinical aspect (Bider et al., 1997). Accordingly, follicular fluid concentrations of cortisol showed no correlation with oocyte number or quality (Bider et al., 1998). Finally, neither follicular fluid concentrations of cortisol and cortisone nor the cortisol:cortisone ratio reflect the quality of ovarian response to gonadotrophin therapy (Andersen et al., 1999).
The importance of human growth hormone for follicular recruitment and selection has not yet been decided (Stone and Marrs, 1992; Levron et al., 1993). Obviously, only patients with human growth hormone deficit profit from an additional human growth hormone therapy along with conventional gonadotrophin ovarian stimulation (de Boer et al., 1999).
Both VEGF as well as VEGFR-1 are up-regulated by hypoxia (Shweiki et al., 1992; Gerber et al., 1997). Oocyte quality is sensitive to hypoxic damage (Van Blerkom, 1998). In contrast, high oxygen content of follicular fluid has been positively correlated with VEGF concentrations (Doldi et al., 1997; Van Blerkom et al., 1997). Other results show that high VEGF concentrations in follicular fluids indicate inferior oocyte quality with poor fertilization rates. It is postulated that elevated VEGF concentrations are a warning sign for insufficient oxygen supply (Barroso et al., 1999).
Elevated serum concentrations of free VEGF have been correlated with an increased risk of severe OHSS (Agrawal et al., 1999; Ludwig et al., 1999). However, measurements of VEGF in serum are compromised by VEGF contributed from platelets during blood clotting (Maloney et al., 1998). Also VEGF plasma concentrations after ovulation induction with HCG have been correlated with the risk of OHSS (Abramov et al., 1997). Again, in these patients the VEGF concentration in follicular fluids is lower than in control patients without risk of OHSS (Pellicer et al., 1999).
The results presented here are in good agreement with data indicating that high concentrations of bio-available VEGF in follicular fluids lead to the pronounced induction of endothelial permeability during OHSS. Consistently, blocking of VEGF action by antibodies or in biological systems by sVEGFR-1 reduces the endothelial permeability (Ferrara et al., 1998; Levin et al., 1998).
Poor ovarian response to gonadotrophin stimulation might be the result of inhibited VEGF bio-availability. Hypoxymia, or oxygen demand, enhances VEGF expression (Gerber et al., 1997) in maturing follicles and augments VEGFR-1 production in corresponding endothelial cells (Shweiki et al., 1992) concomitantly. Alternative splicing of the flt-1 mRNA to produce sVEGFR-1 significantly contributes to the regulation of VEGF activity (He et al., 1999). Rising sVEGFR-1 production and secretion in the vicinity of maturing follicles is detrimental for further development. Thereby, excessive sVEGFR-1 production in ovarian blood vessels results in poor ovarian response due to diminished bio-active VEGF supply. High follicular VEGF production cannot overcome the blocking effects of sVEGFR-1. VEGF concentrations in follicles from those patients may consequently be higher than in women with pronounced ovarian response to gonadotrophin stimuli.
In summary, the data presented here indicate that a delicate balance between VEGF and its natural occurring antagonist sVEGFR-1 is necessary to allow an adequate ovarian reaction to gonadotrophin therapy. Excess of bio-active VEGF increases the risk for OHSS. Excess of sVEGFR-1 results in poor response and reduced chances of conception.
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This study was supported by the Deutsche Forschungsgemeinschaft, grant number Ne 388/5–1 and WE 1211/3–2.
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5 To whom correspondence should be addressed at: Department of Gynecological Endocrinology and Reproductive Medicine,RWTH Aachen, Pauwelsstrasse 30, 52074 Aachen, Germany. E-mail: jneulen{at}post.klinikum.rwth-aachen.de
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References |
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Abramov, Y., Barak, V., Nisman, B. and Schenker, J.G. (1997) Vascular endothelial growth factor plasma levels correlate to the clinical picture in severe hyperstimulation syndrome. Fertil. Steril., 67, 261–265.[Web of Science][Medline]
Agrawal, R., Tan, S.L., Wild, S. et al. (1999) Serum vascular endothelial growth factor concentrations in in vitro fertilization cycles predict the risk of ovarian hyperstimulation syndrome. Fertil. Steril., 71, 287–293.[Web of Science][Medline]
Andersen, C.Y., Morineau, G., Fukuda, M. et al. (1999) Assessment of the follicular cortisol:cortisone ratio. Hum. Reprod., 14, 1562–1568.
Banks, R.E., Forbes, M.A., Searles, J. et al. (1998) Evidence for the existence of a novel pregnancy associated soluble variant of the vascular endothelial growth factor receptor, flt-1. Mol. Hum. Reprod., 4, 377–386.
Barroso, G., Barrionuevo, M., Rao, P. et al. (1999) Vascular endothelial growth factor, nitric oxide, and leptin follicular fluid levels correlate negatively with embryo quality in IVF patients. Fertil. Steril., 72, 1024–1026.[Web of Science][Medline]
Bider, D., Blankstein, J., Levron, J. and Tur-Kaspa, I. (1997) Gonadotropins and glucocorticoid therapy for `low responders' – a controlled study. J. Assist. Reprod. Genet., 14, 328–331.[Web of Science][Medline]
Bider, D., Shine, S., Tur-Kaspa, I. et al. (1998) Cortisol concentrations in follicular fluid of low responder patients. Hum. Reprod., 13, 27–29.
de Boer, J.A., van der Meer, M., van der Veen, E.A. and Schoemaker, J. (1999) Growth hormone (GH) substitution in hypogonadotropic, GH-deficient women decreases the follicle-stimulating hormone threshold for monofollicular growth. J. Clin. Endocrinol. Metab., 84, 590–595.
Doldi, N., Bassan, M., Fusi, F.M. and Ferrari, A. (1997) In controlled ovarian hyperstimulation, steroid production, oocyte retrieval, and pregnancy rate correlate with gene expression of vascular endothelial growth factor. J. Assist. Reprod. Genet., 14, 589–592.[Web of Science][Medline]
Edelstein, M.C., Brzyski, R.G., Jones, G.S. and Muasher, S.J. (1990) Ovarian stimulation for in vitro fertilization in low-responder patients using pulsatile intravenous follicle stimulating hormone. J. In Vitro Fert. Embryo Transf., 7, 275–279.[Web of Science][Medline]
Ferrara, N., Chen, H., Davis-Smyth, T. et al. (1998) Vascular endothelial growth factor is essential for corpus luteum angiogenesis. Nature Med., 4, 336–340.[Web of Science][Medline]
Gerber, H.P., Condorelli, F., Park, J. and Ferrara, N. (1997) Differential transcriptional regulation of the two vascular endothelial growth factor receptor genes. J. Biol. Chem., 272, 23659–23667.
He, Y., Smith, S.K., Day, K.A. et al. (1999) Alternative splicing of vascular endothelial growth factor (VEGF)-R1 (FLT-1) pre-mRNA is important for the regulation of VEGF activity. Mol. Endocrinol., 13, 537–545.
Hofmann, G.E., Toner, J.P., Muasher, S.J. and Jones, G.S. (1989) High-dose follicle-stimulating hormone (FSH) ovarian stimulation in low responder patients for in vitro fertilization. J. In Vitro Fert. Embryo Transf., 6, 285–289.[Web of Science][Medline]
Hornig, C. and Weich, H.A. (1999) Soluble VEGF receptors. Angiogenesis, 3, 33–39.[Medline]
Hornig, C., Behn, T., Bartsch, W. et al. (1999) Detection and quantification of complexed and free soluble human vascular endothelial growth factor receptor-1 (sVEGFR-1) by ELISA. J. Immunol. Meth., 226, 169–177.[Web of Science][Medline]
Hornig, C., Barleon, B., Ahmad, S. et al. (2000) Release and complex formation of soluble VEGFR-1 from endothelial cells and biological fluids. Lab. Invest., 80, 443–454.[Web of Science][Medline]
Kamat, B.R., Brown, L.F., Manseau, E.J. et al. (1995) Expression of vascular permeability factor/vascular endothelial growth factor by human granulosa and theca lutein cells. Role in corpus luteum development. Am. J. Pathol., 146, 157–165.[Abstract]
Karande, V.C., Jones, G.S., Veeck, L.L. and Muasher, S.J. (1990) High-dose follicle-stimulating hormone stimulation at the onset of the menstrual cycle does not improve the in vitro fertilization outcome in low-responder patients. Fertil. Steril., 53, 486–489.[Web of Science][Medline]
Kendall, R.L., Wang, G. and Thomas, K.A. (1996) Identification of a natural soluble form of the vascular endothelial growth factor receptor, flt-1, and its heterodimerization with KDR. Biochem. Biophys Res. Commun., 226, 324–328.[Web of Science][Medline]
Krasnow, J.S., Berga, S.L., Guzick, D.S. et al. (1996) Vascular permeability factor and vascular endothelial growth factor in ovarian hyperstimulation syndrome: a preliminary report. Fertil. Steril., 65, 552–555.[Web of Science][Medline]
Laitinen, M., Ristimaki, A., Honkasalo, M. et al. (1997) Differential hormonal regulation of vascular endothelial growth factors VEGF, VEGF-B, and VEGF-C messenger ribonucleic acid levels in cultured human granulosa-luteal cells. Endocrinology, 138, 4748–4756.
Levin, E.R., Rosen, G.F., Cassidenti, D.L. et al. (1998) Role of vascular endothelial cell growth factor in ovarian hyperstimulation syndrome. J. Clin. Invest., 102, 1978–1985.[Web of Science][Medline]
Levron, J., Lewit, N., Erlik, Y. and Itskovitz-Eldor, J. (1993) No beneficial effects of human growth hormone therapy in normal ovulatory patients with a poor ovarian response to gonadotrophins. Gynecol. Obstet. Invest., 35, 65–68.[Web of Science][Medline]
Ludwig, M., Jelkmann, W., Bauer, O. and Diedrich, K. (1999) Prediction of severe ovarian hyperstimulation syndrome by free serum vascular endothelial growth factor concentration on the day of human chorionic gonadotrophin administration. Hum. Reprod., 14, 2437–2441.
Maloney, J.P., Silliman, C.C., Ambruso, D.R. et al. (1998) In vitro release of vascular endothelial growth factor during platelet aggregation. Am. J. Physiol., 275, 1054–1061.
Moreno, C., Ruiz, A., Simon, C. et al. (1998) Intracytoplasmic sperm injection as a routine indication in low responder patients. Hum. Reprod., 14, 2126–2129.
Muasher, S.J. (1992) Use of gonadotrophin-releasing hormone agonists in controlled ovarian hyperstimulation for in vitro fertilization. Clin. Ther., 14, 74–86.
Neulen, J., Yan, Z., Raczek, S. et al. (1995) Human chorionic gonadotrophin dependent expression of vascular endothelial growth factor/vascular permeability factor in human granulosa cells: importance in ovarian hyperstimulation syndrome. J. Clin. Endocrinol. Metab., 80, 1967–1971.[Abstract]
Neulen, J., Breckwoldt, M., Yan, Z. et al. (1996) Vascular endothelial growth factor/vascular permeability factor expression and production by human luteinized granulosa cells: clinical implications. In Coutifaris, C. and Mastroianni, L. (eds) New Horizons in Reproductive Medicine. Parthenon, New York, pp. 329–332.
Neulen, J., Raczek, S., Pogorzelski, M. et al. (1998) Secretion of vascular endothelial growth factor/vascular permeability factor from human luteinized granulosa cells is human chorionic gonadotrophin dependent. Mol. Hum. Reprod., 4, 203–206.
Otani, N., Minami, S., Yamoto, M. et al. (1999) The vascular endothelial growth factor/fms-like tyrosine kinase system in human ovary during the menstrual cycle and early pregnancy. J. Clin. Endocrinol. Metab., 84, 3845–3851.
Partanen, T.A., Makinen, T., Arola, J. et al. (1999) Endothelial growth factor receptors in human fetal heart. Circulation, 100, 583–586.
Pellicer, A., Ardiles, G., Neuspiller, F. et al. (1998) Evaluation of the ovarian reserve in young low responders with normal basal levels of follicle-stimulating hormone using three-dimensional ultrasonography. Fertil. Steril., 70, 671–675.[Web of Science][Medline]
Pellicer, A., Albert, C., Mercader, A. et al. (1999) The pathogenesis of ovarian hyperstimulation syndrome: in vivo studies investigating the role of interleukin-1ß, interleukin-6, and vascular endothelial growth factor. Fertil. Steril., 71, 482–489.[Web of Science][Medline]
Robertson, D., Selleck, K., Suikkari, A.M. et al. (1995) Urinary vascular endothelial growth factor concentrations in women undergoing gonadotrophin treatment. Hum. Reprod., 10, 2478–2482.
Shibuya, M., Yamaguchi, S., Yamane, A. et al. (1990) Nucleotide sequence and expression of a novel human receptor-type tyrosine gene (flt) closely related to the fms family. Oncogene, 5, 519–524.[Web of Science][Medline]
Shweiki, D., Itin, A., Soffer, D. and Keshet, E. (1992) Vascular endothelial growth factor induced by hypoxia may mediate hypoxia-initiated angiogenesis. Nature, 359, 843–845.[Medline]
Stone, B.A. and Marrs, R.P. (1992) Ovarian response to menopausal gonadotrophins in groups of patients with differing basal growth hormone levels. Fertil. Steril., 58, 32–36.[Web of Science][Medline]
Terman, B., Dougher-Vermazen, M., Carrion, M.E. et al. (1992) Identification of the KDR tyrosine kinase as a receptor for vascular endothelial cell growth factor. Biochem. Biophys Res. Commun., 187, 1579–1586.[Web of Science][Medline]
Van Blerkom, J. (1998) Epigenetic influences on oocyte developmental competence: perifollicular vascularity and intrafollicular oxygen. J. Assist. Reprod. Genet., 15, 226–234.[Web of Science][Medline]
Van Blerkom, J., Antczak, M. and Schrader, R. (1997) The developmental potential of the human oocyte is related to the dissolved oxygen content of follicular fluid: association with vascular endothelial growth factor levels and perifollicular blood flow characteristics. Hum. Reprod., 12, 1047–1055.
Yamamoto, S., Konishi, I., Tsuruta, Y. et al. (1997) Expression of vascular endothelial growth factor (VEGF) during folliculogenesis and corpus luteum formation in the human ovary. Gynecol. Endocrinol., 11, 371–381.[Web of Science][Medline]
Yan, Z., Weich, H.A., Bernart, W. et al. (1993) Vascular endothelial growth factor (VEGF) messenger ribonucleic acid (mRNA) expression in luteinized human granulosa cells in vitro. J. Clin. Endocrinol. Metab., 77, 1723–1725.[Abstract]
Yan, Z., Neulen, J., Raczek, S. et al. (1998) Vascular endothelial growth factor/vascular permeability factor production by luteinized human granulosa cells in vitro: a paracrine signal in corpus luteum formation. Gynecol. Endocrinol., 12, 149–153.[Web of Science][Medline]
Submitted on June 23, 2000; accepted on January 9, 2001.
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 R. Gomez, C. Simon, J. Remohi, and A. Pellicer Administration of Moderate and High Doses of Gonadotropins to Female Rats Increases Ovarian Vascular Endothelial Growth Factor (VEGF) and VEGF Receptor-2 Expression that Is Associated to Vascular Hyperpermeability Biol Reprod, June 1, 2003; 68(6): 2164 - 2171. [Abstract] [Full Text] [PDF]
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J.L. Luborsky, P. Thiruppathi, B. Rivnay, R. Roussev, C. Coulam, and E. Radwanska Evidence for different aetiologies of low estradiol response to FSH: age-related accelerated luteinization of follicles or presence of ovarian autoantibodies Hum. Reprod., October 1, 2002; 17(10): 2641 - 2649. [Abstract] [Full Text] [PDF]
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