Vascular endothelial growth factor (VEGF) and the VEGF soluble receptor-1 (sFlt-1) in chorionic villus tissue from Chinese women with early recurrent spontaneous abortion

Are Altered Expression of Vascular Endothelial Growth Factor and Placental Growth Factor Associated with Placental Angiogenesis in Recurrent Pregnancy Loss?

Angiogenesis is one of the most important steps during pregnancy for placental and fetal development. Based on the hypothesis that vascular insufficiency and altered angiogenesis may lead to early pregnancy loss, the present study was aimed to understand the role of Vascular endothelial growth factor (VEGFA) and Placental growth factor (PLGF) gene expression in placental angiogenesis in the pathogenesis of Recurrent pregnancy loss (RPL). Gene expression analysis of VEGFA and PLGF was carried out in the placental tissue collected from 30 women with recurrent pregnancy loss and compared with the placenta obtained from 16 women with medically terminated pregnancy. The mRNA expression of both VEGFA and PLGF genes were significantly downregulated in the placenta of recurrent pregnancy loss in comparison to the placenta of medically terminated pregnancies. In conclusion the results of the present study suggest that altered expression of VEGFA and PLGF genes in placenta disturb the angiogenesis and contribute to the pathogenesis of recurrent pregnancy loss.

Placenta-Specific miR-125b Overexpression Leads to Increased Rates of Pregnancy Loss in Mice

Pregnancy loss (PL) is one of the common complications that women can experience during pregnancy, with an occurrence rate of 1 to 5%. The potential causes of pregnancy loss are unclear, with no effective treatment modalities being available. It has been previously reported that the level of miR-125b was significantly increased in placentas of PL patients. However, the role of miR-125b in the development of PL still remains unknown. In the current study, an miR-125b placenta-specific over-expression model was constructed by lentiviral transfecting zona-free mouse embryos followed by embryo transfer. On gestation day 15, it was observed that the placenta was significantly smaller in the miR-125b placenta-specific overexpression group than the control group. Additionally, the abortion rate of the miR-125b placenta-specific overexpression group was markedly higher than in the control group. The blood vessel diameter was larger in the miR-125b-overexpressing specific placenta. In addition, miR-125b-overexpressing HTR8 and JEG3 cell lines were also generated to analyze the migration and invasion ability of trophoblasts. The results showed that miR-125b overexpression significantly suppressed the migration and invasion ability of HTR8 and JEG3 cells. Overall, our results demonstrated that miR-125b can affect embryo implantation through modulating placenta angiogenesis and trophoblast cell invasion capacity that can lead to PL.

The role of oxidative stress in patients with recurrent pregnancy loss: a review

BACKGROUND

Recurrent pregnancy loss (RPL) presents one of the main problems in the field of reproductive medicine, due to the unknown etiology in 50% of cases, as well as limited evidence-based diagnostic and therapeutic modalities. Recent studies indicate that systemic and placental oxidative stress (OS) represents an essential factor in the etiopathogenesis of RPL. This article is a comprehensive narrative synthesis of previously published studies concerning the role of oxidative stress in the etiology of recurrent pregnancy loss.

METHODS

We conducted literature search of published studies in the English language focusing on oxidative stress and its association with recurrent pregnancy loss (RPL) utilizing the Medline and Cochrane databases from 2000 through January 2021. The keywords used were "recurrent pregnancy loss" "oxidative stress and recurrent pregnancy loss" and "oxidative stress biomarkers and recurrent pregnancy loss".

RESULTS

The search yielded 1116 publications, of which 92 were included in the final analysis. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) at basal levels have various physiological functions whereas deviation from redox window is associated with different pathologies including early pregnancy loss. The currently available studies support the concept that increased oxidative stress (OS) and deficient antioxidant protection is implicated in the etiology of recurrent pregnancy loss (RPL) but underlying mechanisms through which OS affects pregnancy outcome remains largely indefinable.

CONCLUSIONS

Future research in this field can provide new insights regarding the OS-mediated damage in recurrent pregnancy loss as well as potential applications of antioxidant therapy in this group of patients.

Imbalance of growth factors mRNA expression associated with oxidative stress in the early pregnancy loss

OBJECTIVE

The aim of this study was to examine the role of growth factors associated with angiogenesis and oxidative stress in the pathogenesis of spontaneous miscarriage.

METHODS

We performed a comparative mRNA expression analysis of VEGF, PlGF, Flt-1, Angiogenin and Endoglin using Real-Time PCR, in the placenta and decidua collected from 12 patients presenting with spontaneous abortion and from 14 women undergoing induced abortion, during the first and second trimester of pregnancy.

RESULTS

The mRNA expression of Flt-1 was significantly upregulated in the placenta of spontaneous abortions (5.17-fold, IQR: 2.72-9.11, p < 0.01). The placental expression of the soluble isoforms of Flt-1, sFlt-1 e15a and sFlt-1 i13, was also significantly upregulated in spontaneous abortions (sFlt-1 e15a: 2.35-fold, IQR: 0.98-2.83, p < 0.01; sFlt-1 i13: 3.47-fold, IQR: 2.37-5.08, p < 0,05). Placental tmFlt-1, PlGF and Endoglin showed a tendency of higher expression levels in spontaneous abortions, although they did not reach statistical significance (tmFlt-1: 7.42-fold, IQR: 3.58-14.32; PlGF: 2.36-fold, IQR: 0.90-4.12; Endoglin: 1.97-fold, IQR: 1.18-2.43). VEGF and Angiogenin mRNA expression in induced, as well as in spontaneous abortions, did not convey any statistically significant difference. In the decidua, the expression levels of Flt-1 and its splice variants sFlt-1 e15a, sFlt-1 i13 and tmFlt-1 did not show any statistically significant differences, as was the case for the rest of the herein examined growth factors.

CONCLUSIONS

In this study, we observed higher levels of sFlt-1 mRNA expression in the placenta of spontaneous abortions, while expression of other growth factors in placenta and decidua remained constant. This suggests that an imbalance of sFlt-1 expression in the placenta might contribute to the pathogenesis of spontaneous abortion, probably via oxidative stress, providing a possible biomarker for prompt identification of this condition.

Role of Vascular Endothelial Growth Factor (VEGF) in Human Embryo Implantation: Clinical Implications

Vascular endothelial growth factor (VEGF) is a well-known angiogenic factor that plays a critical role in various physiological and pathological processes. VEGF also contributes to the process of embryo implantation by enhancing embryo development, improving endometrial receptivity, and facilitating the interactions between the developing embryo and the endometrium. There is a correlation between the alteration of VEGF expression and reproductive failure, including recurrent implantation failure (RIF) and recurrent miscarriage (RM). In order to clarify the role of VEGF in embryo implantation, we reviewed recent literature concerning the expression and function of VEGF in the reproductive system around the time of embryo implantation and we provide a summary of the findings reported so far. We also explored the effects and the possible underlying mechanisms of action of VEGF in embryo implantation.

The -2549 insertion/deletion polymorphism in the promoter region of VEGF is associated with the risk of recurrent spontaneous abortion

Recurrent spontaneous abortion (RSA) is a common health problem affecting women of reproductive age. Altered expression of vascular endothelial growth factor (VEGF) has been associated with spontaneous abortion. The present case-control study aimed to evaluate the impact of the 18-bp insertion/deletion (ins/del) polymorphism (rs35569394) in the promoter region of the VEGF gene on idiopathic RSA. Genomic DNA from 93 patients with RSA and 93 healthy fertile women of southeastern Iran was isolated using the salting-out method. Genotyping of the rs35569394 variant was performed by a polymerase chain reaction (PCR) method. The findings indicated that the VEGF 18-bp ins/del variant significantly increased the risk of RSA under codominant (ins/ins vs. del/del; OR=2.85, 95% CI=1.31-6.22, P=0.019), dominant (del/ins+ins/ins vs. del/del; OR=2.19, 95% CI=1.20-4.01, P=0.015) and allelic (ins vs. del; OR=1.90, 95% CI=1.25-2.88, P=0.003) inheritance models. In summary, the findings propose a significant association between the VEGF 18-bp ins/del polymorphism and risk of RSA in a sample of the southeast Iranian population. Further studies on larger sample sizes and different ethnicities are required to validate the present findings.

Reduced expressions of connexin 43 and VEGF in the first-trimester tissues from women with recurrent pregnancy loss

BACKGROUND

Approximately 45-50 % of the recurrent pregnancy loss (RPL) remain(s) unexplained that challenges its clinical management. Formation and development of placenta as well as angiogenesis are critical for successful pregnancy. Vascular endothelial growth factor (VEGF) and connexin 43 (Cx43) play important roles in angiogenesis and placenta development and aberration of these have been linked to RPL. We aimed to investigate whether the expressions of VEGF and Cx43 were altered in the first-trimester tissues (chorionic villi and decidua) collected from women with RPL compared to those from healthy early pregnant women.

METHODS

First-trimester chorionic villi and decidua were collected from pregnant women diagnosed RPL who ended up with surgical intervention (n = 28) in comparison to those collected from women requesting surgical termination of their unwanted normal first-trimester pregnancies (n = 28). These two groups of women were matched in age and gestational weeks. Tissues were analyzed for the protein and messenger ribonucleic acid (mRNA) expressions of Cx43 and VEGF by immunohistochemistry, western blot, and quantitative reverse transcription polymerase chain reaction (qRT-PCR).

RESULTS

The expressions of both Cx43 and VEGF at the level of mRNA and protein in the villi and decidua from women with RPL were significantly decreased compared with those from women with normal early pregnancy.

CONCLUSIONS

Reduction of Cx43 and VEGF expressed in the first-trimester tissues might indicate their important roles involved in RPL and thus holds the potential to develop pharmaceutical therapies for treatment of RPL.

The relationship between the VEGF/sVEGFR-1 ratio and threatened abortion

PURPOSE

The aim of this study was to evaluate the levels of vascular endothelial growth factor (VEGF), soluble VEGF receptor-1 (sVEGFR-1) and placenta growth factor (PlGF) and VEGF/SVEGFR-1 ratio in pregnant women with threatened abortion (TA) compared to uncomplicated pregnancies at the same gestational week.

METHODS

Thirty-three pregnant women with TA and thirty-three pregnant women with uncomplicated pregnancies were included in this case-control study. The level of VEGF, sVEGFR-1, and PIGF was analyzed by enzyme-linked immunosorbent assay (ELISA). The primary purpose of this study was to compare the VEGF, sVEGFR- 1, and PlGF levels and VEGF/sVEGFR-1 ratios in pregnant women with TA and pregnant women with uncomplicated pregnancies. The secondary purpose of this study was to evaluate the correlation between serum levels of these markers and gestational age.

RESULTS

The serum levels of the sVEGFR-1 [0.60 (0.21-1.68) vs. 0.24 (0.09-0.57) ng/ml], VEGF [39.10 (6.57-163.56) vs. 5.24 (0.84-15.08) ng/ml] and VEGF/SVEGFR-1 ratio [68.64 (6.45-550.48) vs 24.12 (2.63-72.63)] were significantly elevated in women with TA (respectively, p: 0.001, p: 0.001, p: 0.001). However, PlGF did not elevate in women with TA [20.80 (3.13-93.11) vs 20.16 (1.22-49.91) ng/ml] (p: 0.473).

CONCLUSION

These findings support the hypothesis that increased levels of the VEGF and sVEGFR-1 and VEGF/SVEGFR-1 ratio may be associated with the pathogenesis of TA.

An increase in vascular endothelial growth factor (VEGF) and VEGF soluble receptor-1 (sFlt-1) are associated with early recurrent spontaneous abortion

Recurrent spontaneous abortion (RSA) is a health problem that affects approximately 1% to 5% reproductive age woman. Yet, in around half of these patients, the mechanism for RSA is unexplained. Recent studies have indicated that placental ischemia/hypoxia and endothelial dysfunction are important factors in miscarriage. Other studies have indicated that the level and expression of soluble FMS-like tyrosine kinase-1 (sFlt1) is increased under a hypoxic environment. However, decreased sFlt-1 in the maternal circulation during the first trimester has recently been proposed as a potential marker for identifying risk of pregnancy loss. In this prospective study clinical samples were obtained within a short time after the fetal death, protein expression and maternal serum levels of sFlt1 were assessed and compared to samples taken from those with normal pregnancies. Our results indicate that levels of VEGF and sFlt-1 are both increased in women during early pregnancy compared women that are not pregnant (p<0.05) indicating that VEGF and sFlt-1 are both associated with pregnancy. More importantly, we detected a significant (p<0.05) increase in sFlt1 and VEGF levels and expression in the RSA patients who suffered subsequent miscarriages compare to controls. These results demonstrate that there is likely a relationship between VEGF, sFlt-1 and RSA suggesting that the high levels and over expression of sFlt-1 and VEGF might be associated with the pathogenesis of RSA.