The role of progesterone in endometrial angiogenesis in pregnant and ovariectomised mice

Study on 20-hydroxyprogesterone: Chiral resolution, content determination and progesterone-like activity

20-hydroxyprogesterone (20-DHP) is a natural metabolite of progesterone which occurs with two diastereoisomers: 20α-DHP and 20β-DHP. They have drawn attention for their progesterone-like activity since the middle of the 20th century. However, the literature from that era bears witness to a lack of consensus regarding their specific effects. Considered that their stereoisomerism differences, it is essential to investigate their biological activities in vivo separately. In this study, we presented a chemical synthesis technique that yielded highly pure samples of 20α-DHP and 20β-DHP, and performed simultaneous content analysis. Subsequently, we examined and contrasted the progesterone-like properties of 20α-DHP, 20β-DHP, and a 1:1 mixture of 20α-DHP and 20β-DHP. The Morphological observations of the endometrium were conducted via Haematoxylin-eosin staining. Serum hormone levels were measured using enzyme-linked immunosorbent assays. Furthermore, real-time fluorescence quantitative polymerase chain reaction and immunohistochemistry were employed to analyse the relevant mRNA and protein expression, respectively. Our comparison revealed that 20α-DHP and P4 share identical progesterone-like actions, while 20β-DHP exhibits partial similarity. The progesterone activity varied when the two were combined in a 1:1 ratio.

The impact of FSH stimulation and age on the ovarian and uterine traits and histomorphometry of prepubertal gilts

This study investigated the effect of age and follicle stimulating hormone (FSH) treatment on the estradiol (E2) plasma concentration, ovarian follicle development, endometrial histomorphometry, and ultrasonographic parameters of the ovaries and uterus in prepubertal gilts. Thirty-five prepubertal gilts were grouped according to age (140 or 160 d), and within each age, gilts were allotted to receive 100 mg of FSH (treated; G140 + FSH [n = 10] and G160 + FSH [n = 7]) or saline solution (control; G140 + control [n = 10] and G160 + control [n = 8]). The total dose of FSH was divided into 6 similar doses administered every 8 h (days 0-2). Before and after FSH treatment, blood sample was collected, and transabdominal scanning of the ovaries and uterus was performed. Twenty-four hours after the last FSH injection, the gilts were slaughtered and their ovaries and uterus were processed for histological and histomorphometric analysis. The histomorphometric parameters of the uterus differed (P < 0.05) between prepubertal gilts at 160 d and 140 d of age. Moreover, changes (P < 0.05) in uterine and ovarian ultrasound images occurred between 140 and 160 d of age. Age and FSH treatment did not affect (P > 0.05) E2 plasma concentrations. Follicle stimulating hormone treatment did not affect (P > 0.05) the early stage of folliculogenesis in the prepubertal gilts; however, the number of early atretic follicles decreased (P < 0.05) after the FSH treatment. Follicle stimulating hormone administration increased (P < 0.05) the number of medium follicles and decreased (P < 0.05) the number of small follicles in 140 and 160 d old gilts. In the endometrium, luminal/glandular epithelium height and glandular diameter increased (P < 0.05) after FSH treatment. Thus, injections of 100 mg of FSH stimulate the endometrium epithelium and induce follicular growth to a medium follicle size without affecting the preantral stages in prepubertal gilts; also, the uterine macroscopic morphometry does not change from 140 to 160 d of age.

Progress on the Role of Estrogen and Progesterone Signaling in Mouse Embryo Implantation and Decidualization

Embryo implantation and decidualization are key steps in establishing a successful pregnancy. Defects in embryo implantation and decidualization can cause a series of adverse chain reactions which can contribute to harmful pregnancy outcomes, such as embryo growth retardation, preeclampsia, miscarriage, premature birth, and so on. Approximately 75% of failed pregnancies are considered to be due to embryo implantation failure or defects. Decidualization, characterized by proliferation and differentiation of uterine stromal cells, is one of the essential conditions for blastocyst implantation, placental formation, and maintenance of pregnancy and is indispensable for the establishment of pregnancy in many species. Embryo implantation and decidualization are closely regulated by estrogen and progesterone secreted by the ovaries. Many cellular events and molecular signaling network pathways are involved in this process. This article reviews the recent advances in the molecular mechanisms of estrogen- and progesterone-regulating uterine receptivity establishment, blastocyst implantation, and decidualization, in order to better understand the underlying molecular mechanisms of hormonal regulation of embryo implantation and to develop new strategies for preventing or treating embryo implantation defects and improving the pregnancy rate of women.

Role of progesterone on dexamethasone-induced alterations in placental vascularization and progesterone receptors in rats†

BACKGROUND

Intrauterine growth restriction (IUGR) is manifested by lower maternal progesterone levels, smaller placental size, and decreased placental vascularity indicated by lower expression of vascular endothelial growth factor (VEGF). Studies showed that progesterone increases angiogenesis and induces VEGF expression in different tissues. Therefore, the aim of the present study is to evaluate the effect of progesterone on placental vascular bed and VEGF expression and the modulation of nuclear and membranous progesterone receptors (PR) in dexamethasone-induced rat IUGR model.

METHODS

Pregnant Sprague-Dawley rats were allocated into four groups and given intraperitoneal injections of either saline, dexamethasone, dexamethasone, and progesterone or progesterone. Injections started on gestation day (DG) 15 and lasted until the days of euthanization (19 and 21 DG). Enzyme-linked immunosorbent assay was used to evaluate plasma progesterone levels. Real-time PCR and western blotting were used to evaluate gene and protein expressions of VEGF, and PR in labyrinth and basal placental zones. Immunohistochemistry was used to locate VEGF and different PRs in placental cells. Immunofluorescence was used to monitor the expression of blood vessel marker (αSMA).

RESULTS

Dexamethasone decreased the vascular bed fraction and the expression of VEGF in both placental zones. Progesterone co-treatment with dexamethasone prevented this reduction. Nuclear and membrane PRs showed tissue-specific expression in different placental zones and responded differently to both dexamethasone and progesterone.

CONCLUSIONS

Progesterone treatment improves the outcomes in IUGR pregnancy. Progesterone alleviated DEX-induced IUGR probably by promoting placental VEGF and angiogenesis.

The Regulators of Human Endometrial Stromal Cell Decidualization

Several factors are important for implantation and subsequent placentation in the endometrium, including immunity, angiogenesis, extracellular matrix, glucose metabolism, reactive oxidative stress, and hormones. The involvement or abnormality of these factors can impair canonical decidualization. Unusual decidualization can lead to perinatal complications, such as disruption of trophoblast invasion. Drastic changes in the morphology and function of human endometrial stromal cells (hESCs) are important for decidualization of the human endometrium; hESCs are used to induce optimal morphological and functional decidualization in vitro because they contain estrogen and progesterone receptors. In this review, we will focus on the studies that have been conducted on hESC decidualization, including the results from our laboratory.

Comparison of mechanisms of angiostasis caused by the anti-inflammatory steroid 5α-tetrahydrocorticosterone versus conventional glucocorticoids

5α-Tetrahydrocorticosterone (5αTHB) is an effective topical anti-inflammatory agent in mouse, with less propensity to cause skin thinning and impede new blood vessel growth compared with corticosterone. Its anti-inflammatory effects were not prevented by RU38486, a glucocorticoid receptor antagonist, suggesting alternative mechanisms. The hypothesis that 5αTHB directly inhibits angiogenesis to a lesser extent than hydrocortisone was tested, focussing on glucocorticoid receptor mediated actions. New vessel growth from aortae from C57BL/6 male mice was monitored in culture, in the presence of 5αTHB, hydrocortisone (mixed glucocorticoid/mineralocorticoid receptor agonist) or the selective glucocorticoid receptor agonist dexamethasone. Transcript profiles were studied, as was the role of the glucocorticoid receptor, using the antagonist, RU38486. Ex vivo, 5αTHB suppressed vessel growth from aortic rings, but was less potent than hydrocortisone (EC50 2512 nM 5αTHB, versus 762 nM hydrocortisone). In contrast to conventional glucocorticoids, 5αTHB did not alter expression of genes related to extracellular matrix integrity or inflammatory signalling, but caused a small increase in Per1 transcript, and decreased transcript abundance of Pecam1 gene. RU38486 did not antagonise the residual effects of 5αTHB to suppress vessel growth or regulate gene expression, but modified effects of dexamethasone. 5αTHB did not alter expression of glucocorticoid-regulated genes Fkbp51 and Hsd11b1, unlike hydrocortisone and dexamethasone. In conclusion, compared with hydrocortisone, 5αTHB exhibits limited suppression of angiogenesis, at least directly in blood vessels and probably independent of the glucocorticoid receptor. Discriminating the mechanisms employed by 5αTHB may provide the basis for the development of novel safer anti-inflammatory drugs for topical use.

Three-Dimensional Visualization of Mouse Endometrial Remodeling After Superovulation

Uterine status determines pregnancy success. Although it is well known that superovulation operations can disrupt uterine function, our understanding of the morphological changes in the uterine endometrium at the three-dimensional (3D) level is limited. Here, combining the tissue clearing with 3D deep imaging, we reveal an increase in epithelial density and angiogenesis after ovarian stimulation, which is accompanied by a circulating surge in P4 levels. Using an ovariectomized mouse model, we further detected the separate regulatory effects of P4 and E2 on the uterine endometrium, with P4 promoting endothelial cell growth and E2 inducing epithelial proliferation. Additionally, we observed that the effects of E2 can be partially neutralized by P4, and vice versa. By analyzing the 3D uterine imaging, we discovered an interesting phenomenon in which the growing blood vessels closely surround the remodeling uterine epithelium, indicating a close relationship between angiogenesis and epithelial growth. These findings provide new insight into the uterine epithelial changes and angiogenesis at the 3D level, and explain a potential reason for endometrial changes due to the low implantation rate in patients undergoing clinic super-ovulation.

Delayed Implantation Induced by Letrozole in Mice

Implantation timing is critical for a successful pregnancy. A short delay in embryo implantation caused by targeted gene ablation produced a cascading problem in the later stages of the pregnancy. Although several delayed implantation models have been established in wild mice, almost none of them is suitable for investigating the early delay's effects on the late events of pregnancy. Here, we report a new delayed implantation model established by the intraperitoneal administration of letrozole at 5 mg/kg body weight on day 3 of pregnancy. In these mice, initiation of implantation was induced at will by the injection of estradiol (E2). When the estradiol (3 ng) was injected on day 4 of pregnancy (i.e., without delay), the embryo implantation restarted, and the pregnancy continued normally. However, 25 ng estrogen caused compromised implantation. We also found that 67% of the female mice could be pregnant normally and finally gave birth when the estradiol injection (3 ng) was on day 5 of pregnancy (i.e., 1-day delay). Most failed pregnancies had impaired decidualization, decreased serum progesterone levels, and compromised angiogenesis. Progesterone supplementation could rescue decidualization failure in the mice. Collectively, we established a new model of delayed implantation by letrozole, which can be easily applied to study the effect and mechanisms of delay of embryo implantation on the progression of late pregnancy events.

Solving the Puzzle: What Is the Role of Progestogens in Neovascularization?

Ovarian sex steroids can modulate new vessel formation and development, and the clarification of the underlying mechanism will provide insight into neovascularization-related physiological changes and pathological conditions. Unlike estrogen, which mainly promotes neovascularization through activating classic post-receptor signaling pathways, progesterone (P4) regulates a variety of downstream factors with angiogenic or antiangiogenic effects, exerting various influences on neovascularization. Furthermore, diverse progestins, the synthetic progesterone receptor (PR) agonists structurally related to P4, have been used in numerous studies, which could contribute to unequal actions. As a result, there have been many conflicting observations in the past, making it difficult for researchers to define the exact role of progestogens (PR agonists including naturally occurring P4 and synthetic progestins). This review summarizes available evidence for progestogen-mediated neovascularization under physiological and pathological circumstances, and attempts to elaborate their functional characteristics and regulatory patterns from a comprehensive perspective.

Progesterone and vitamin D downregulate the activation of the NLRP1/NLRP3 inflammasomes and TLR4-MyD88-NF-κB pathway in monocytes from pregnant women with preeclampsia

This study evaluated the in vitro modulatory effect of progesterone (PG) and vitamin D (VD) on NLRP1/NLRP3 inflammasomes and TLR4/NF-κB pathway in monocytes from pregnant women with preeclampsia (PE). Monocytes from 20 preeclamptic and 20 normotensive (NT) pregnant women, and THP-1 cells were cultured with/without hyaluronan (HA), PG, or VD to determine gene and protein expression of TLR4 receptor, phosphorylated NF-κB, IκBα, TLR4, MYD88, NF-κB, NLRP1, NLRP3, caspase-1, IL-1β, IL-18, TNF-α, and IL-10. Higher endogenous activation of inflammatory genes and higher protein expression of TLR4 and NF-κB was detected in monocytes of PE group and decreased after PG or VD treatment. Monocyte from PE stimulated with HA increased while treatment with PG or VD decreased the expression of genes and proteins related to the inflammasomes. THP-1 cells showed a similar immune response profile as monocytes from PE. These results demonstrate that PG and VD play an immunomodulatory role in monocyte activation.

Histomorphometric analysis of goat uterine tissue on in vitro exposure with ovarian hormones and mifepristone

Uterus, the largest reproductive tract organ in female mammals, is the site of implantation of fertilised egg and foetus development. Uterus is a dynamic reproductive organ; its morphology alters with reproductive phase and steroidal cues. The aim of the present study was to assess the effects of progesterone (P4), estrogen (E2) and antiprogestogen i.e., mifepristone on goat’s uterine histoarchitecture in in vitro short term culture. Uterine tissue slices were cultured in the presence of E2, P4 and mifepristone at the dose of 10–9 M, 10–7 M and 10–6 M respectively for 24 hours. Uter-ine morphology of E2- and P4-treated groups did not reveal marked changes from that of control group. Mifepristone treatment caused conspicuous changes in uterine histoarchitecture, led to congested endometrium, regressed uterine glands and constricted blood vessels. The changes ob-served in morphometry after E2 and P4 exposure included increased uterine gland diameter (47.00 and 45.95 µm respectively) and glandular epithelial cell height (18.37 and 17.43 µm respectively) while the mifepristone treatment resulted in significant reduction of gland diameter (34.95 µm) as well as epithelium height (14.25 µm) as compared to those in control group (39.9 and 15.56 µm respectively). These morphometrical changes revealed prominent regressive changes in anti-progestin treated group while E2 and P4 showed prolific effects in in vitro culture. Thus it is envis-aged that E2 and P4 induced characteristic progressive changes in the histologic structure especially in endometrial glands of the goat uterus while anti-steroidogenic formulation i.e. mifepristone severely reduced the normal histoarchitecture of the uterus which is a prerequisite for implanta-tion.

Effects of Erbuzhuyu Decoction Combined with Acupuncture on Endometrial Receptivity Are Associated with the Expression of miR-494-3p

Background/Aim

Erbuzhuyu decoction (EBZYD) is a traditional Chinese medicine (TCM) formula and has been used in infertility treatment. Meanwhile, acupuncture is also used to treat female infertility. However, it is unclear whether EBZYD combined with acupuncture has better therapeutic effect. The aim of this study was to explore the effect of EBZYD combined with acupuncture and investigate its mechanism in superovulation mice.

Methods

The mice received the treatment of EBZYD, acupuncture, EBZYD combined with acupuncture, or miR-494-3p agomir combined with EBZYD and acupuncture. The blastocysts' number, endometrial microstructure, and endometrial thickness were observed, followed by the detection of endometrial receptivity-related factors, PI3K/Akt/mTOR pathway-related proteins, and miR-494-3p expression using quantitative real-time polymerase chain reaction (qRT-PCR) or western blot. Luciferase reporter assay was performed to confirm the targeting relationship between HOXA10 and miR-494-3p.

Results

EBZYD combined with acupuncture treatment could increase the number of blastocysts, pinopodes, endometrial thickness, and the expression of endometrial receptivity-related factors, and the treatment effect of EBZYD combined with acupuncture was better than EBZYD or acupuncture alone. In addition, EBZYD combined with acupuncture treatment activated PI3K/Akt/mTOR pathway and inhibited the expression of miR-494-3p. HOXA10 is one of the target genes of miR-494-3p. Overexpression of miR-494-3p reversed the therapeutic effect of EBZYD combined with acupuncture and suppressed the expression of HOXA10 and the activity of PI3K/Akt/mTOR pathway.

Conclusion

This study suggests that EBZYD combined with acupuncture could improve endometrial receptivity in superovulation mice via miR-494-3p/HOXA10 axis.

Evaluating the effect of ovarian stimulation and exogenous progesterone on CD31-positive cell density, VEGF protein, and miR-17-5p expression of endometrium immediately before implantation

BACKGROUND

MicroRNAs (miRNAs) form a special class of RNAs regulating endometrial functions like cell proliferation, differentiation, angiogenesis, and blastocyst implantation. In addition to providing suitable conditions for embryo development, angiogenesis is a prerequisite to natural pregnancy. The family of vascular endothelial growth factor (VEGF) and its receptors are the main physiological and pathological angiogenesis regulators in the endometrium. In the past, research has demonstrated alteration of angiogenesis and subsequent endometrial receptivity in the stimulated and luteal phase support cycles, when compared with natural cycles.

OBJECTIVE

The objective of this study is to investigate the effect of ovarian stimulation and exogenous progesterone on the density of CD31-positive cell (Endothelial cell), VEGF protein, and miR-17-5p expression in the mouse endometrium immediately before implantation.

METHODS

We employed ovarian stimulated and luteal phase support mice models induced by HMG/HCG and progesterone. The endometrial CD31-positive cell density was determined by immunohistochemistry (IHC) staining, the level of VEGF protein by IHC and western blot analysis, and finally the miR-17-5p expression was determined by the real-time PCR method.

RESULTS

The density of endothelial cell, VEGF protein, and miR-17-5p expression increased in all of the experimental mice when compared to the control group, with the maximum increase having been seen in the group that had received progesterone after ovarian stimulation.

CONCLUSION

This research indicates that ovarian stimulation and exogenous progesterone lead to an increase in the number of endothelial cells by upregulating the VEGF protein. Moreover, except for miR-17-5p, other microRNAs and molecules are presumably involved in angiogenic pathways, thereby requiring more studies.

Ovarian stimulation and exogenous progesterone affect the endometrial miR-16-5p, VEGF protein expression, and angiogenesis

Angiogenesis, where vascular endothelial growth factor (VEGF) is critically involved, is an important factor in endometrial receptivity. Angio-miRNAs form a special class of microRNAs (miRNAs) that target angiogenic genes and regulate angiogenesis. Various studies have shown that ovarian stimulation and exogenous progesterone affect endometrial vascular density. The present research aimed to assess the impact of HMG/HCG and progesterone on miR-16-5p, VEGF protein expression, and angiogenesis in the mouse endometrium during the preimplantation period. Forty adult female mice were divided into four groups: 1) control, 2) ovarian stimulation (HMG and 48 h after HCG IP), 3) progesterone (progesterone IP for 3 days), 4) ovarian stimulation + progesterone (HMG and 48 h after HCG IP) + (progesterone IP for 3 days) groups.The mice were sacrificed 96 h following HCG administration. miR-16-5p, VEGF protein expression, and CD31-positive cell (Endothelial cell) density were specified.The results showed that endothelial cell density,VEGF protein, and miR-16-5p expression increased in all treatment groups, with the maximum increase belonging to the ovarian stimulation + progesterone group. This study provides evidence that ovarian stimulation and progesterone administration enhance endometrial angiogenesis through VEGF protein upregulation. Furthermore, except for miR-16-5p, other miRNAs and molecules appear to be involved in angiogenic pathways, thereby requiring further studies.

Angiopoietin-2 regulated by progesterone induces uterine vascular remodeling during pregnancy

During pregnancy, the uterus undergoes intense neovascularization and vascular remodeling to supply oxygen and nutrients to the embryo. During this period, progesterone secreted from the ovary has effects on vascular remodeling in the endometrium and interacts with angiogenic factors. However, the exact mechanism of uterine vascular remodeling during pregnancy is poorly understood. Therefore, the aim of the present study was to investigate the association between angiopoietin-2 (Ang-2), one of the angiopoietins, and intrauterine vessel remodeling during pregnancy, and to determine the effect of progesterone on Ang-2 levels. Changes in Ang-2 expression were observed according to quantitative modification of progesterone using pregnant mice and human uterine microvascular endothelial cells. As a result, Ang-2 was observed mainly in the mesometrial region (MR) of the uterus during the period between implantation and placentation. Furthermore, a substantial amount of Ang-2 also appeared in endothelial cells, particularly of the venous sinus region (VSR). Interestingly, Ang-2 expression was increased by progesterone, whereas estrogen had limited effects. To confirm the association between Ang-2 and progesterone, the function of the progesterone receptor (PR) was inhibited using RU486, a blocker of PR. Ang-2 expression and vascular remodeling of the VSR in the uterus were decreased when the functions of progesterone were inhibited. Overall, the regulation of Ang-2 by progesterone/PR was associated with vascular remodeling in the VSR during pregnancy. The present study proposed a solution to prevent pregnancy failure due to a lack of vascularity in the uterus in advance.

Spectrum of meningioma with special reference to prognostic utility of ER,PR and Ki67 expression

BACKGROUND:

Meningiomas are the most common primary central nervous system neoplasms originating from the arachnoid cap cells and constitute between 13% and 26% of all intracranial tumors.

AIMS AND OBJECTIVES:

The aim of the study was to analyze the age-, sex-, and site-wise distribution of different histological patterns of meningiomas seen in our center and to assess the status of estrogen receptor (ER), progesterone receptor (PR), and proliferation marker Ki-67 in various grades of meningioma.

MATERIALS AND METHODS:

A prospective study was done in 90 cases. Patients presented with symptoms of headache and seizure and underwent subsequent excision surgery at Neurosurgery Department were taken. We have studied histological typing and grading of the tumors, and immunohistochemical staining was done for ER, PR, and Ki-67.

STATISTICAL ANALYSIS:

Two-group comparison was done using Mann–Whitney U-test and Fisher's exact test. Comparison of Ki-67 expression between Grade 1 and Grade 2 meningiomas was determined using Mann–Whitney U-test. Comparison of ER and PR status between different histological grades was done by Fisher's exact test. Two-tailed P < 0.001 was considered statistically significant.

RESULTS:

According to histological type, meningothelial meningioma is most common (38.8%) followed by transitional (22.2%). PR positivity is seen in 96.34% of Grade 1 tumors, and all Grade 2 tumors were PR negative (Fisher's exact test P < 0.001). About 3.66% of Grade 1 and all Grade 2 tumors were positive for ER (Fisher's exact test two-tailed P < 0.001). Mean Ki-67 labeling index (LI) was 2.57 ± 1.674 among Grade I tumors, 7.11 ± 1.084 in Grade II meningiomas.

CONCLUSIONS:

Most of Grade 1 meningiomas show PRs positivity and lack of ERs positivity. Meningiomas with higher proliferation index and negative PR are very likely to be Grade II or Grade III. Evaluation of ER, PR status, and Ki-67 labeling index (LI) with histological evaluation helps us in providing information about the biologic behavior of meningiomas.

Progesterone Intramuscularly or Vaginally Administration May Not Change Live Birth Rate or Neonatal Outcomes in Artificial Frozen-Thawed Embryo Transfer Cycles

BACKGROUNDS

Previous studies suggested that singletons from frozen-thawed embryo transfer (FET) were associated with higher risk of large, post-date babies and adverse obstetrical outcomes compared to fresh transfer and natural pregnancy. No data available revealed whether the adverse perinatal outcomes were associated with aberrantly high progesterone level from different endometrium preparations in HRT-FET cycle. This study aimed to compare the impact of progesterone intramuscularly and vaginally regimens on neonatal outcomes in HRT-FET cycles.

METHODS

A total of 856 HRT-FET cycles from a fertility center from 2015 to 2018 were retrospectively analyzed. All patients had their first FET with two cleavage-staged embryos transferred. Endometrial preparation was performed with sequential administration of estrogen followed by progesterone intramuscularly 60 mg per day or vaginal gel Crinone 90 mg per day. Pregnancy outcomes including live birth rate, singleton birthweight, large for gestational age (LGA) rate, small for gestational age (SGA) rate, and preterm delivery rate were analyzed. Student's t test, Mann-Whitney U-test, Chi square analysis, and multivariable logistic regression were used where appropriate. Differences were considered significant if p < 0.05.

RESULTS

No significant difference of live birth rate was found between different progesterone regimens (Adjusted OR 1.128, 95% CI 0.842, 1.511, p = 0.420). Neonatal outcomes like singleton birthweight (p = 0.744), preterm delivery rate (Adjusted OR 1.920, 95% CI 0.603, 6.11, p = 0.269), SGA (Adjusted OR 0.227, 95% CI 0.027, 1.934, p = 0.175), and LGA rate (Adjusted OR 0.862, 95% CI 0.425, 1.749, p=0.681) were not different between two progesterone regimens. Serum P level >41.82 pmol/L at 14 day post-FET was associated with higher live birth rate than serum P level ≤41.82 pmol/L in HRT-FET cycles when progesterone was intramuscularly delivered (Adjusted OR 1.690, 95% CI 1.002, 2.849, p = 0.049). But singleton birthweight, preterm delivery rate, SGA and LGA rate were not different between these two groups.

CONCLUSIONS

Relatively higher serum progesterone level induced by intramuscular regimen did not change live birth rate or neonatal outcomes compared to vaginal regimen. Monitoring serum progesterone level and optimizing progesterone dose of intramuscular progesterone as needed in HRT-FET cycles has a role in improving live birth rate without impact on neonatal outcomes.

Evidence of proteinuria, but no other characteristics of pre-eclampsia, in relaxin-deficient mice

Pre-eclampsia (PE) is a leading cause of maternal and fetal death, characterised by an imbalance of placental growth factors and hypertension at >20 weeks gestation. Impaired maternal systemic vascular adaptations and fetal growth restriction are features of both PE and pregnant relaxin-deficient (Rln^-/-) mice. The aim of the present study was to investigate whether these phenotypes in Rln^-/- mice are associated with abnormal placental growth factor expression, increased soluble fms-like tyrosine kinase-1 (sFlt-1), proteinuria and/or hypertension during pregnancy. In addition, we examined relaxin and relaxin receptor (relaxin/insulin like family peptide receptor 1 (RXFP1)) mRNA expression in placentas of women with PE. There was no significant difference in placental vascular endothelial growth factor A (VegfA) and placenta growth factor (Plgf) gene expression between Rln^-/- and wild-type mice. Circulating plasma sFlt-1 concentrations in pregnant mice of both genotypes and ages were increased compared with non-pregnant mice but were lower in younger pregnant Rln^-/- mice compared with aged-matched Rln^+/+ mice. Aged pregnant Rln^-/- mice had higher urinary albumin:creatinine ratios compared with age-matched Rln^+/+ mice, indicative of proteinuria. Systolic and diastolic blood pressures did not differ between genotypes. In addition, PE in women was not associated with altered placental mRNA expression of RLN2 or RXFP1 at term. Overall, the data demonstrate that pregnant Rln^-/- mice do not have the typical characteristics of PE. However, these mice show evidence of proteinuria, but we suggest that this results from systemic renal vascular dysfunction before pregnancy.

Supraphysiologic estradiol is an independent predictor of low birth weight in full-term singletons born after fresh embryo transfer

STUDY QUESTION

Is supraphysiologic estradiol (E2) an independent predictor of low birth weight (LBW) in singletons born after fresh IVF-embryo transfer (ET) cycles?

SUMMARY ANSWER

Our results suggest that E2 > 2500 pg/ml is an independent predictor for LBW in full-term singletons born to normal responder patients undergoing fresh IVF-ET cycles.

WHAT IS KNOWN ALREADY

The pathogenesis of LBW in IVF singletons remains unknown. However, recent studies have suggested that the hyperestrogenic milieu generated during ovarian stimulation may create a sub-optimal peri-implantation environment, leading to placental dysfunction, and therefore, LBW.

STUDY DESIGN, SIZE, DURATION

Retrospective cohort study of normal responder patients, <40 years old, undergoing fresh IVF-ET cycles resulting in live singleton births between January 2005 and June 2014.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 6419 patients had live births after fresh IVF-ET during the study period, of which 2348 (36.6%) patients were excluded due to multiple gestation, vanishing twins or incomplete records. Perinatal outcomes recorded for all patients included birth weight, gestational age (GA) at delivery, mode of delivery and gender. Term birth, preterm birth (PTB) and LBW incidence proportions were plotted against E2 level on the day of trigger. The term LBW incidence proportion (i.e. singletons born at GA ≥ 37 weeks with birth weight <2500 g) was considered the primary outcome of interest.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 4071 patients with live singleton births were included. The median age, BMI, E2 level and birth weight for the study cohort was 36 (33-39) years, 22.3 (20.4-25.0) kg/m2, 1554 (1112.7-2179) pg/ml and 3289 (2920-3628) g, respectively. The incidence proportion of LBW rose from 6.4% (E2 2001-2500 pg/ml) to 20.7% (E2 3501-4000 pg/ml), without a corresponding rise in the incidence proportion of PTB. The odds of term LBW with E2 > 2500 pg/ml were 6.1-7.9 times higher compared to the referent E2 group. Multivariable logistic regression analysis revealed that E2 was an independent predictor for term LBW, even after adjusting for age, BMI, race, parity, infertility diagnosis, duration of ovarian stimulation, gonadotropin dosage and method of insemination (adjusted odds ratio 10.8, 95% CI 9.2-12.5). Receiver operating characteristic analysis generated an AUC estimate of 0.85 for E2 level as a predictor of LBW.

LIMITATIONS REASONS FOR CAUTION

The current study did not include analyses of hypertensive disorders of pregnancy or placental abnormalities. Furthermore, all patients were normal responders and of normal BMI, possibly limiting the overall generalizability of the study. Finally, as with any retrospective study, prospective data are required to validate the role of E2 in predicting LBW.

WIDER IMPLICATIONS OF THE FINDINGS

Our results emphasize the importance of minimizing the supraphysiologic elevations of E2 levels during ovarian stimulation in fresh IVF-ET cycles. This, in turn, can optimize the early peri-implantation environment and mitigate adverse perinatal outcomes such as LBW.

STUDY FUNDING/COMPETING INTEREST(S)

Dr Paul J. Christos was partially supported by the following grant: Clinical and Translational Science Center at Weill Cornell Medical College (UL1-TR000457-06).

TRIAL REGISTRATION NUMBER

N/A.

Bushen Huoxue Recipe Alleviates Implantation Loss in Mice by Enhancing Estrogen-Progesterone Signals and Promoting Decidual Angiogenesis Through FGF2 During Early Pregnancy

Bushen Huoxue recipe (BSHXR) is a classic Chinese herbal prescription for nourishing the kidney and activating blood circulation. It consists of six herbs: Astragali radix, Angelicae sinensis radix, Ligustici Chuanxiong Rhizoma, Cuscutae semen, Taxilli Herba, and Dipsaci Radix, and the main active constituents of BSHXR are ferulic acid, calycosin-7-glucopyranoside, hyperoside, quercitrin, and asperosaponin VI. In clinical practice, BSHXR is traditionally used to treat failed pregnancy and its complications. However, little is known about the underlying mechanism of BSHXR for the treatment of implantation loss during early pregnancy. In the current study, controlled ovarian hyperstimulation was induced in mice as our implantation loss model, and we evaluated the effects of BSHXR on implantation, decidualization, decidual angiogenesis, and reproductive outcome. We showed that BSHXR could regulate the supraphysiological levels of serum estrogen and progesterone observed in these mice, and also act on estrogen and progesterone receptors in the stroma and epithelium. BSHXR also enhanced FGF2 expression in the vascular sinus folding area of the decidua, thus potentially reducing implantation loss during early pregnancy and contributing to placentation and survival of the fetuses. Taken together, our findings provide scientific evidence for the application of BSHXR in the clinic as a treatment for implantation loss during early pregnancy, and warrant further investigation of BSHXR as an effective treatment for failed pregnancy and its complications.

HIV antiretroviral exposure in pregnancy induces detrimental placenta vascular changes that are rescued by progesterone supplementation

Adverse birth outcomes are common in HIV-positive pregnant women receiving combination antiretroviral therapy (cART), especially when cART is initiated in early pregnancy. The mechanisms remain poorly understood. Using a mouse model we demonstrate that protease inhibitor based-cART exposure beginning on day 1 of pregnancy was associated with a pro-angiogenic/pro-branching shift in the placenta driven by lower Flt-1 levels and higher Gcm-1 expression. Micro-CT imaging revealed an increase in the number of arterioles in cART-treated placentas, which correlated with fetal growth restriction. Delaying initiation of cART, or supplementing cART-treated mice with progesterone, prevented the pro-angiogenic/pro-branching shift and the associated placenta vascular changes. In agreement with our mouse findings, we observed an increase in the number of terminal-villi capillaries in placentas from HIV-positive cART-exposed women compared to HIV-negative controls. Capillary number was inversely correlated to maternal progesterone levels. Our study provides evidence that cART exposure during pregnancy influences placenta vascular formation that may in turn contribute to fetal growth restriction. Our findings highlight the need for closer investigation of the placenta in HIV-positive pregnancies, particularly for pregnancies exposed to cART from conception, and suggest that progesterone supplementation could be investigated as a possible intervention to improve placenta function in HIV-positive pregnant women.

Ovarian Hyperstimulation Reduces Vascular Endothelial Growth Factor-A During Uterine Receptivity

The angiogenic factor vascular endothelial growth factor-A (VEGFA) plays a critical role during early pregnancy in many species including the rat, and any alterations in VEGFA levels can severely impact blastocyst implantation rates. The rat ovarian hyperstimulation (OH) model is useful in studying how the induction of superovulation affects VEGFA levels and endometrial receptivity to blastocyst implantation. The present study shows that the major isoform in the rat uterus, Vegf₁₈₈, is reduced at the time of receptivity in OH compared to normal pregnancy, whereas there is no change in Vegf₁₆₄ and Vegf₁₂₀ messenger RNA (mRNA). The VEGFA receptor 2 (VEGFR2) protein levels are also reduced at the time of receptivity in OH. Our ovariectomy studies show that Vegf₁₆₄, Vegf₁₈₈, and Vegf₁₂₀ are significantly decreased by estrogen, and, to a lesser extent progesterone, when compared to control animals. Although no change in the percentage of endometrial blood vessels was seen across all stages of pregnancy, at the time of receptivity in OH pregnancies, blood vessels were typically larger compared to other stages. The altered progesterone-estrogen ratio seen in OH, taken together with our ovariectomy studies, explains the changes to Vegfa mRNA in OH at the time of receptivity. Since VEGFA is important during implantation, the changes to Vegfa and VEGFR2 levels in the endometrium may help explain the observed lower endometrial receptivity following OH. This study aimed to analyse how ovarian hyperstimulation alters the levels of vascular endothleial growth factor and its major receptor, VEGFR2 in the uterus in a rat model.

ADC at 3.0 T as a noninvasive biomarker for preoperative prediction of Ki67 expression in invasive ductal carcinoma of breast

PURPOSE

To investigate the role of apparent diffusion coefficient (ADC) as an imaging biomarker for invasive ductal carcinoma (IDC) in the breast.

METHODS

Seventy-one patients undergoing 3.0 Tesla DWI were retrospectively enrolled. Correlations between the ADC values and prognostic factors were evaluated.

RESULTS

Multivariate regression analyses showed that Ki67 expression and molecular subtype were independently associated with the ADC. Discriminant analysis excluded the ADC as a good biomarker for subtype, but the mean ADC significantly distinguished Ki67-positive (low ADC) from Ki67-negative (high ADC) lesions, as observed in the in ROC curves, with a diagnostic sensitivity of 1.00 and a cut-off value of 0.97 × 10^-3 mm²/s.

CONCLUSION

The ADC may be helpful for predicting Ki67 expression in IDC preoperatively.

Progesterone-mediated angiogenic activity of endothelial progenitor cell and angiogenesis in traumatic brain injury rats were antagonized by progesterone receptor antagonist

OBJECTIVES

Progesterone (P4) has the potential therapeutic effects for traumatic brain injury (TBI) whose recovery depended on the enhanced angiogenesis. Endothelial progenitor cell (EPC) plays an essential role in vascular biology. We previously demonstrated that P4 administration improved circulating EPC level and neurological recovery of rat with TBI. Here, we hypothesized that P4 augmented angiogenic potential of EPC and the angiogenesis-related neurorestoration after TBI through classical progesterone receptor (PR).

MATERIALS AND METHODS

EPC derived from rats were stimulated with graded concentrations (0, 10^-10 , 10^-9 , 5 × 10^-9 , 10^-8 , 10^-7  mol/L) of P4 or 10^-6  mol/L ulipristal acetate (UPA, a PR antagonist). Male rats were subjected to cortical impact injury and treated with (i) DMSO (dimethyl sulfoxide), (ii) P4 and (iii) P4 and UPA.

RESULTS

It showed that P4 improved the angiogenic potential of EPC, including tube formation, adhesion, migration and vascular endothelial growth factor secretion, in a dose-dependent fashion with the maximal effect achieved at 10^-9  mol/L P4. High concentration (10^-7  mol/L) of P4 impaired the angiogenic potential of EPC. Notably, 10^-6  mol/L UPA antagonized the stimulatory effects of 10^-9  mol/L P4. After administrating P4, a significant improvement of neurological function and the restoration of the leaked blood-brain barrier were observed as well as a reduction of the brain water content. Both vessel density and expression of occludin of vessels were increased. When UPA was administered with P4, the neural restoration and angiogenesis were all reversed. Western blot showed that 10^-9  mol/L P4 increased the content of PRA and PRB of EPC, while 10^-7  mol/L P4 reduced the content of both PR isoforms, but there was no change found in the TBI rats.

CONCLUSIONS

It may suggest that P4-mediated angiogenic activity of EPC and angiogenesis in TBI rats were antagonized by PR antagonist.

Mapping of estradiol binding sites through receptor micro-autoradiography in the endometrial stroma of early pregnant mice

Estradiol triggers key biological responses in the endometrium, which rely on the presence and levels of its cognate receptors on target cells. Employing the receptor micro-autoradiography (RMAR) technique, we aimed to provide a temporal and spatial map of the functional binding sites for estradiol in the mouse endometrial stroma during early pregnancy. Uterine samples from days 1.5 to 7.5 of pregnancy were collected 1 h after tritiated- (3H-) estradiol administration and prepared for RMAR analysis. Autoradiographic incorporation of 3H-thymidine (after 1-h pulse) was evaluated over the same gestational interval. Combined RMAR with either histochemistry with Dolichus biflorus (DBA) lectin or immunohistochemistry for detection of the desmin further characterized 3H-estradiol binding pattern in uterine Natural Killer (uNK) and decidual cells, respectively. 3H-estradiol binding levels oscillated in the pregnant endometrial stroma between the mesometrial and antimesometrial regions as well as the superficial and deep domains. Although most of the endometrial stromal cells retained the hormone, a sub-population of them, as well as endothelial and uNK cells, were unable to do so. Rises in the levels of 3H-estradiol binding preceded endometrial stromal cell proliferation. 3H-estradiol binding and 3H-thymidine incorporation progressively decreased along the development of the antimesometrial decidua. Endothelial proliferation occurred regardless of 3H-estradiol binding, whereas pericytes proliferation was associated with high levels of hormone binding. Endometrial cell populations autonomously control their levels of 3H-estradiol binding and retention, a process associated with their proliferative competence. Collectively, our results illustrate the intricate regulatory dynamic of nuclear estrogen receptors in the pregnant mouse endometrium.

Pivotal Cytoprotective Mediators and Promising Therapeutic Strategies for Endothelial Progenitor Cell-Based Cardiovascular Regeneration

Cardiovascular diseases (CVDs), including atherosclerosis, stroke, and myocardial infarction, is a major cause of death worldwide. In aspects of cell therapy against CVD, it is generally accepted that endothelial progenitor cells (EPCs) are potent neovascular modulators in ischemic tissues. In response to ischemic injury signals, EPCs located in a bone marrow niche migrate to injury sites and form new vessels by secreting various vasculogenic factors including VEGF, SDF-1, and FGF, as well as by directly differentiating into endothelial cells. Nonetheless, in ischemic tissues, most of engrafted EPCs do not survive under harsh ischemic conditions and nutrient depletion. Therefore, an understanding of diverse EPC-related cytoprotective mediators underlying EPC homeostasis in ischemic tissues may help to overcome current obstacles for EPC-mediated cell therapy for CVDs. Additionally, to enhance EPC's functional capacity at ischemic sites, multiple strategies for cell survival should be considered, that is, preconditioning of EPCs with function-targeting drugs including natural compounds and hormones, virus mediated genetic modification, combined therapy with other stem/progenitor cells, and conglomeration with biomaterials. In this review, we discuss multiple cytoprotective mediators of EPC-based cardiovascular repair and propose promising therapeutic strategies for the treatment of CVDs.

Nuclear Factor Erythroid 2-Related Factor 2 Deficiency Results in Amplification of the Liver Fat-Lowering Effect of Estrogen

Transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) regulates multiple biologic processes, including hepatic lipid metabolism. Estrogen exerts actions affecting energy homeostasis, including a liver fat-lowering effect. Increasing evidence indicates the crosstalk between these two molecules. The aim of this study was to evaluate whether Nrf2 modulates estrogen signaling in hepatic lipid metabolism. Nonalcoholic fatty liver disease (NAFLD) was induced in wild-type and Nrf2-null mice fed a high-fat diet and the liver fat-lowering effect of exogenous estrogen was subsequently assessed. We found that exogenous estrogen eliminated 49% and 90% of hepatic triglycerides in wild-type and Nrf2-null mice with NAFLD, respectively. This observation demonstrates that Nrf2 signaling is antagonistic to estrogen signaling in hepatic fat metabolism; thus, Nrf2 absence results in striking amplification of the liver fat-lowering effect of estrogen. In addition, we found the association of trefoil factor 3 and fatty acid binding protein 5 with the liver fat-lowering effect of estrogen. In summary, we identified Nrf2 as a novel and potent inhibitor of estrogen signaling in hepatic lipid metabolism. Our finding may provide a potential strategy to treat NAFLD by dually targeting Nrf2 and estrogen signaling.

Relaxin deficiency results in increased expression of angiogenesis- and remodelling-related genes in the uterus of early pregnant mice but does not affect endometrial angiogenesis prior to implantation

BACKGROUND

Extensive uterine adaptations, including angiogenesis, occur prior to implantation in early pregnancy and are potentially regulated by the peptide hormone relaxin. This was investigated in two studies. First, we took a microarray approach using human endometrial stromal (HES) cells treated with relaxin in vitro to screen for target genes. Then we aimed to investigate whether or not relaxin deficiency in mice affected uterine expression of representative genes associated with angiogenesis and uterine remodeling, and also blood vessel proliferation in the pre-implantation mouse endometrium.

METHODS

Normal HES cells were isolated and treated with recombinant human relaxin (10 ng/ml) for 24 h before microarray analysis. Reverse transcriptase PCR was used to analyze gene expression of relaxin and its receptor (Rxfp1) in ovaries and uteri; quantitative PCR was used to analyze steroid receptor, angiogenesis and extracellular matrix remodeling genes in the uteri of wild type (Rln+/+) and Rln-/- mice on days 1-4 of pregnancy. Immunohistochemistry localized endometrial endothelial cell proliferation and mass spectrometry measured steroid hormones in the plasma.

RESULTS

Microarray analysis identified 63 well-characterized genes that were differentially regulated in HES cells after relaxin treatment. Expression of some of these genes was increased in the uterus of Rln+/+ mice by day 4 of pregnancy. There was significantly higher vascular endothelial growth factor A (VegfA), estrogen receptor 1 (Esr1), progesterone receptor (Pgr), Rxfp1, egl-9 family hypoxia-inducible factor 1 (Egln1), hypoxia inducible factor 1 alpha (Hif1α), matrix metalloproteinase 14 (Mmp14) and ankryn repeat domain 37 (Ankrd37) in Rln-/- compared to Rln+/+ mice on day 1. Progesterone receptor expression and plasma progesterone levels were higher in Rln-/- mice compared to Rln+/+ mice. However, endometrial angiogenesis was not advanced as pre-implantation endothelial cell proliferation did not differ between genotypes.

CONCLUSIONS

Relaxin treatment modulates expression of a variety of angiogenesis-related genes in HES cells. However, despite accelerated uterine gene expression of steroid receptor, progesterone and angiogenesis and extracellular matrix remodeling genes in Rln-/- mice, there was no impact on angiogenesis. We conclude that although relaxin deficiency results in phenotypic changes in the pre-implantation uterus, endogenous relaxin does not play a major role in pre-implantation angiogenesis in the mouse uterus.

Hormonal regulation of pigment epithelium-derived factor (PEDF) expression in the endometrium

Pigment epithelium-derived factor (PEDF) is highly expressed in the female reproductive system and is subjected to regulation by steroid hormones in the ovary. As the uterine endometrium exhibits morphological and functional changes in response to estrogen (E2) and progesterone (P4), we aimed at characterizing the expression of PEDF in this component of the female reproductive tract and further at exploring the hormonal regulation of its expression. We found that PEDF is expressed in human and mouse endometrium. We further showed that this expression is subjected to regulation by steroid hormones, both in vivo and in vitro, as follows: E2 decreased PEDF expression and P4 increased its levels. In human endometrial samples, PEDF levels were dynamically altered along the menstrual cycle; they were low at the proliferative and early secretory phases and significantly higher at the late secretory phase. The expression levels of PEDF were inversely correlated to that of vascular endothelial growth factor (VEGF). We also showed that PEDF receptor was expressed in the endometrium and that its stimulation reduced VEGF expression. Illustrating the pattern of PEDF expression during the menstrual cycle may contribute to our understanding of the endometrial complexity.

Why we should transfer frozen instead of fresh embryos: the translational rationale

Epidemiologic studies have shown an increased rate of adverse perinatal outcomes, including small for gestational age (SGA) births, in fresh in vitro fertilization (IVF) cycles compared with frozen embryo transfer cycles. This increase is not seen in the donor oocyte population, suggesting that it is the peri-implantation environment created after superovulation that is responsible for these changes. During a fresh IVF cycle, multiple corpora lutea secrete high levels of hormones and other factors that can affect the endometrium and the implanting embryo. In this review, we discuss both animal and human data demonstrating that superovulation has significant effects on the endometrium and embryo. Additionally, potential mechanisms for the adverse effects of gonadotropin stimulation on implantation and placental development are proposed. We think that these data, along with the growing body of epidemiologic evidence, support the proposal that frozen embryo transfer should be considered preferentially, particularly in high responders, as a means to potentially decrease at least some of the adverse perinatal outcomes associated with IVF.

Estrogen decreases the expression of claudin-5 in vascular endothelial cells in the murine uterus

Vascular endothelial (VE)-cadherin and claudin-5 are major components of the adherens and tight junctions of vascular endothelial cells, respectively, and decreases in their expression are associated with increases in endothelial paracellular permeability. In the uterus, estrogen induces endometrial edema. However, the in vivo effect of estrogen on endothelial paracellular permeability is unknown. Therefore, we studied the expression of VE-cadherin and claudin-5 in vascular endothelial cells in murine uteri stimulated by estrogen or progesterone. Ovariectomized mature mice were injected with estradiol-17β (1 μg/mouse) or progesterone (1 mg/mouse) at intervals of 24 hours for 6 days. The frozen transverse sections of the uteri of these mice and untreated mice were stained for CD31 (vascular endothelial cell marker) plus VE-cadherin or claudin-5 using a double-immunofluorescence method. Then, the percentages of VE-cadherin- or claudin-5-positive vessels among CD31-positive vessels were examined in the uterine endometria. VE-cadherin and claudin-5 were expressed in most CD31-positive vessels in the endometria of the untreated mice. Progesterone did not affect the expression of both VE-cadherin and claudin-5 and estradiol-17β also did not affect the VE-cadherin expression, but estradiol-17β significantly decreased the claudin-5 expression. This decreasing effect of estradiol-17β was detected from 24 hours later when the water content per a uterus significantly increased. The present study indicates that estrogen, but not progesterone, decreases the expression of claudin-5 in vascular endothelial cells in the murine uterine endometrium from 24 hours later, suggesting that the decrease in the claudin-5 expression contributes to the endometrial edema late after the estrogen stimulation.

VEGF-A regulated by progesterone governs uterine angiogenesis and vascular remodelling during pregnancy

The features and regulation of uterine angiogenesis and vascular remodelling during pregnancy are poorly defined. Here we show that dynamic and variable decidual angiogenesis (sprouting, intussusception and networking), and active vigorous vascular remodelling such as enlargement and elongation of ‘vascular sinus folding’ (VSF) and mural cell drop-out occur distinctly in a spatiotemporal manner in the rapidly growing mouse uterus during early pregnancy — just after implantation but before placentation. Decidual angiogenesis is mainly regulated through VEGF-A secreted from the progesterone receptor (PR)-expressing decidual stromal cells which are largely distributed in the anti-mesometrial region (AMR). In comparison, P₄-PR-regulated VEGF-A-VEGFR2 signalling, ligand-independent VEGFR3 signalling and uterine natural killer (uNK) cells positively and coordinately regulate enlargement and elongation of VSF. During the postpartum period, Tie2 signalling could be involved in vascular maturation at the endometrium in a ligand-independent manner, with marked reduction of VEGF-A, VEGFR2 and PR expressions. Overall, we show that two key vascular growth factor receptors — VEGFR2 and Tie2 — strikingly but differentially regulate decidual angiogenesis and vascular remodelling in rapidly growing and regressing uteri in an organotypic manner.

Evidence of steroid hormone activity in the chorioallantoic membrane of a Turtle (Pseudemys nelsoni)

Endocrine properties of extraembryonic membranes have traditionally been viewed as a characteristic of placental amniotes. However, our laboratory recently demonstrated that this ability extends to the extraembryonic membranes of two oviparous amniotes (chicken and alligator) indicating that endocrine extraembryonic membranes are not an innovation of placental amniotes and suggesting that this could be a shared amniote characteristic. In this study, we test our hypothesis that the chorioallantoic membrane (CAM) obtained from non-archosaurian obligate oviparous amniotes such as turtles, have the potential for steroid hormone activity. To investigate synthesis of a major placental hormone, we performed explant culture and found that the turtle CAM synthesizes progesterone in vitro in the presence of a steroid precursor. In addition, to examine whether the CAM has the ability to respond to steroid signaling, we quantified mRNA expression of the progesterone, androgen, and two estrogen receptors. Finally, to determine if steroid receptor mRNA is translated to protein, we performed immunolocalization of the progesterone receptor. Our data demonstrate that the turtle CAM exhibits steroid synthesis and has steroid hormone signaling capabilities. To that end, steroid hormone activity has now been demonstrated in the CAMs of three oviparous species that represent three independent lineages within oviparous Reptilia that have never exhibited viviparity; thus these data support our hypothesis that endocrine activity of extraembryonic membranes is a conserved trait of Amniota.

Endometrial regeneration and endometrial stem/progenitor cells

The functional layer of the human endometrium is a highly regenerative tissue undergoing monthly cycles of growth, differentiation and shedding during a woman's reproductive years. Fluctuating levels of circulating estrogen and progesterone orchestrate this dramatic remodeling of human endometrium. The thin inactive endometrium of postmenopausal women which resembles the permanent basal layer of cycling endometrium retains the capacity to respond to exogenous sex steroid hormones to regenerate into a thick functional endometrium capable of supporting pregnancy. Endometrial regeneration also follows parturition and endometrial resection. In non menstruating rodents, endometrial epithelium undergoes rounds of proliferation and apoptosis during estrus cycles. The recent identification of adult stem cells in both human and mouse endometrium suggests that epithelial progenitor cells and the mesenchymal stem/stromal cells have key roles in the cyclical regeneration of endometrial epithelium and stroma. This review will summarize the evidence for endometrial stem/progenitor cells, examine their role in mouse models of endometrial epithelial repair and estrogen-induced endometrial regeneration, and also describe the generation of endometrial-like epithelium from human embryonic stem cells. With markers now available for identifying endometrial mesenchymal stem/stromal cells, their possible role in gynecological diseases associated with abnormal endometrial proliferation and their potential application in cell-based therapies to regenerate reproductive and other tissues will be discussed.

Progesterone stimulates expression of follistatin splice variants Fst288 and Fst315 in the mouse uterus

Follistatin, an inhibitor of activin A, has key regulatory roles in the female reproductive tract. Follistatin has two splice variants: FST288, largely associated with cell surfaces, and FST315, the predominant circulating form. The mechanism regulating uterine expression of these variants is unknown. Quantitative RT-PCR was used to measure expression of follistatin splice variants (Fst288, Fst315), the activin bA subunit (Inhba) and the inhibin a subunit (Inha) in uterine tissues during early pregnancy (days 1–4, preimplantation) and in response to exogenous 17b-oestradiol (single s.c. injection) and progesterone (three daily s.c. injections) in ovariectomized mice. Uterine Fst288, Fst315 and Inhba expression increased during early pregnancy, with greater increases in Fst315 relative to Fst288 suggesting differential regulation of these variants. Fst288, Fst315, Inhba and Inha all increased in response to progesterone treatment. Fst288, but not Fst315, mRNA decreased in response to 17b-oestradiol treatment, whereas Inhba increased. A comparison of the absolute concentrations of uterine follistatin mRNA using crossing thresholds indicated that both variants were more highly expressed in early pregnancy in contrast to the hormone treatment models. It is concluded that progesterone regulates uterine expression of both follistatin variants, as well as activin A, during early pregnancy in the mouse uterus

Effects of α and β recombinant FSH (Gonal-F, Puregon) and progesterone upon human endometrial cell proliferation in-vitro: a preliminary study

Endometrial proliferation or regeneration during menstrual cycle is regulated by sexual hormones. However, the effect of gonadotrophins on the endometrial cell growth remains obscure. Herein, we aimed to investigate the effects of r-FSH (Gonal-F, Puregon) and progesterone on the proliferation of human endometrial cells in-vitro. According as gonadotrophin concentrations, the follicular-phase endometrial cells were divided into six groups: (1) 0 (controls), (2) 1; (3) 10; (4) 100; (5) 1000; (6) 100,000 μIU/ml. The cell countings with microscopy and cell proliferation kit assay were used to assess the endometrial cell proliferations. In Gonal-F groups, the cell absorptions (%) after 24/48 h culture were: (1) 100/100; (2) 103.8/102.3; (3) 104.8/102.8; (4) 102.3/101.3; (5) 96.3/94.2; (6) 86.8/84.3. In Puregon groups, the cell absorptions were: (1) 100/100; (2) 102.8/101.9; (3) 103/102.3; (4) 103.9/103.5; (5) 102.9/102.4; (6) 103.7/103.2 (non-different). In progesterone groups, the cell absorptions were: (1) 100/100; (2) 99.1/101.9; (3) 83.5/80.4; (4) 80.7/82.4. Higher dosage of Gonal-F (100,000 μIU/ml) and progesterone (10, 100 μg/ml) appeared the significant inhibition upon endometrium. We conclude that lower dosages of Gonal-F, Puregon, and progesterone appear the non-significant influence upon endometrium. Higher dosage of Gonal-F (10,000 μIU/ml) and progesterone (10, 100 μg/ml), but not Puregon, might interfere with the endometrial proliferation during follicular phase.

Vascular endothelial growth factor-A isoform and (co)receptor expression are differentially regulated by 17β-oestradiol in the ovariectomised mouse uterus

The angiogenic effects of 17β-oestradiol (E2) in the mouse endometrium are mediated by vascular endothelial growth factor-A (VEGFA). We analysed the temporal and spatial changes in VEGFA isoform and (co)receptor expression in ovariectomised mouse uteri following E2 treatment. VEGFA isoform and receptor mRNA were quantified in whole uterine tissue collected 2, 6, 12 and 24 h after E2 or vehicle treatment. Laser capture microdissection was used to investigate mRNA expression in epithelial, stromal and myometrial tissues separately. Endothelial cell proliferation, VEGFA and VEGF receptor-2 (VEGFR2) protein were visualised using immunohistochemistry. Endometrial endothelial cell proliferation was only observed 24 h after E2 treatment. In whole uterine tissue, total Vegfa, Vegfa164 and Vegfa120 mRNA expression increased 2 h post E2 treatment, and then decreased by 24 h. Vegfa188 expression was lower in E2-treated animals at all time points relative to control animals. Vegfr2 and neuropilin-1 (Nrp1) mRNA expression did not change following E2 treatment; Nrp2 expression decreased by 24 h. When uterine compartments were considered separately at 24 h post E2 or vehicle, stromal Vegfa120, Vegfa188 and Vegfr2 mRNA expression and myometrial Vegfa120 and Vegfa188 mRNA expression were reduced in E2-treated mice relative to controls, whereas epithelial Vegfa188 mRNA expression increased. The highest VEGFA immunoexpression was observed in luminal epithelium; expression increased at 24 h relative to other time points. No changes were noted in VEGFR2 immunoexpression among treatment groups. We have provided the first evidence that VEGFA isoform and receptor mRNA expression are differentially regulated by E2 in different uterine cell compartments.

Differential expression of vascular endothelial growth factor-A isoforms in the mouse uterus during early pregnancy

While vascular endothelial growth factor (VEGF)-A mediates endometrial vascular remodelling during early pregnancy in mice, individual VEGF-A isoforms have not been investigated, despite their different biological properties. Using mice as a model, the expression of VEGF-A isoforms and receptors in the mouse uterus during early pregnancy was quantified. It was postulated that selected isoform expression would increase concurrent with increased endometrial endothelial cell proliferation at this time. Uteri were collected on days 1-5 of pregnancy and mRNA expression was quantified by quantitative reverse-transcription polymerase chain reaction, VEGF-A protein by Western blot and VEGF receptor (VEGFR)-2 by immunohistochemistry. The lowest expression of isomers Vegf(120) and Vegf(164) was observed on day 2 of pregnancy, increasing thereafter. Vegfr-2 mRNA expression was significantly higher on days 3-5 of pregnancy relative to days 1-2 (P<0.05). No significant changes were noted in Vegf(188), Nrp1 or Nrp2 mRNA. VEGF(188) protein expression was consistently higher than other isoforms. These data demonstrate differential regulation of VEGF-A isoforms in mouse uterus during early pregnancy.

Vascular endothelial growth factor-D over-expressing tumor cells induce differential effects on uterine vasculature in a mouse model of endometrial cancer

BACKGROUND

It has been hypothesised that increased VEGF-D expression may be an independent prognostic factor for endometrial cancer progression and lymph node metastasis; however, the mechanism by which VEGF-D may promote disease progression in women with endometrial cancer has not been investigated. Our aim was to describe the distribution of lymphatic vessels in mouse uterus and to examine the effect of VEGF-D over-expression on these vessels in a model of endometrial cancer. We hypothesised that VEGF-D over-expression would stimulate growth of new lymphatic vessels into the endometrium, thereby contributing to cancer progression.

METHODS

We initially described the distribution of lymphatic vessels (Lyve-1, podoplanin, VEGFR-3) and VEGF-D expression in the mouse uterus during the estrous cycle, early pregnancy and in response to estradiol-17beta and progesterone using immunohistochemistry. We also examined the effects of VEGF-D over-expression on uterine vasculature by inoculating uterine horns in NOD SCID mice with control or VEGF-D-expressing 293EBNA tumor cells.

RESULTS

Lymphatic vessels positive for the lymphatic endothelial cell markers Lyve-1, podoplanin and VEGFR-3 profiles were largely restricted to the connective tissue between the myometrial circular and longitudinal muscle layers; very few lymphatic vessel profiles were observed in the endometrium. VEGF-D immunostaining was present in all uterine compartments (epithelium, stroma, myometrium), although expression was generally low. VEGF-D immunoexpression was slightly but significantly higher in estrus relative to diestrus; and in estradiol-17beta treated mice relative to vehicle or progesterone treated mice. The presence of VEGF-D over-expressing tumor cells did not induce endometrial lymphangiogenesis, although changes were observed in existing vessel profiles. For myometrial lymphatic and endometrial blood vessels, the percentage of profiles containing proliferating endothelial cells, and the cross sectional area of vessel profiles were significantly increased in response to VEGF-D in comparison to control tumor cells. In contrast, no significant changes were noted in myometrial blood vessels. In addition, examples of invading cells or tumor emboli were observed in mice receiving VEGF-D expressing 293EBNA cells.

CONCLUSIONS

These results illustrate that VEGF-D over-expression has differential effects on the uterine vasculature. These effects may facilitate VEGF-D's ability to promote endometrial cancer metastasis and disease progression.

Vasculogenesis and angiogenesis in the endometrium during menstrual cycle and implantation

Blood vessels develop via two subsequent processes, vasculogenesis and angiogenesis, both being of crucial importance during menstrual cycle and implantation. These processes are also involved in the development of the fetal and placental vasculatures. During vasculogenesis, formation of the earliest primitive capillaries is achieved by in situ differentiation of hemangiogenic stem cells that are derived from pluripotent mesenchymal cells. The subsequent process, angiogenesis, is characterized by development of new vessels from already existing vessels, and is a well coordinated process initiated by stimulation of various growth factors. Vasculogenesis and angiogenesis are important and complex processes involving extensive interplay between cells and growth factors. The development, maturation and maintenance of the vascular network are necessary for successful hemochorial placentation as well as normal embryonic development and growth. In this review, we outline the basic mechanisms of vasculogenesis and angiogenesis in the endometrium during the menstrual cycle and different stages of implantation, and consider how this data can be applied to human pregnancy. Recent studies have shown that during the initiation steps of implantation, angiogenic factors trigger vasculogenesis and angiogenesis. Different inducers and stimulators affect angiogenesis and vasculogenesis by directly or indirectly stimulating proliferation, differentiation and migration of endothelial or respective precursor cells. As a conclusion, understanding the mechanisms of angiogenesis and the roles of angiogenic factors during the menstrual cycle and implantation may provide new insights and possible approaches for embryo implantation and healthy pregnancy.

Epigenetic regulation of endometrium during the menstrual cycle

The endometrium undergoes morphological and functional changes during the menstrual cycle which are essential for uterine receptivity. These changes are driven by estrogen and progesterone and involve the fine control of many different genes-several of which have been identified as being epigenetically regulated. Epigenetic modification may therefore influence the functional changes in the endometrium required for successful implantation. There is, however, only limited information on epigenetic regulation in endometrium. We review the potential role of epigenetic regulation of key processes during the menstrual cycle and present our own findings following a preliminary study into global acetylation levels in the human endometrium. A changing epigenetic state is associated with the differentiation of stem cells into different lineages and thus may be involved in endometrial regeneration. Histone acetylation is implicated in the vascular endothelial growth factor pathway during angiogenesis, and studies using histone deacetylase inhibitors suggest an involvement in endometrial proliferation and differentiation. The processes of decidualization and implantation are also associated with epigenetic change and epigenetic modulators show variable expression across the menstrual cycle. Our own studies found that endometrial global histone acetylation, as determined by western blotting, changed throughout the menstrual cycle and correlated well with expected transcription activity during the different phases. This suggests that epigenetics may be involved in the regulation of endometrial gene expression during the menstrual cycle and that abnormal epigenetic modifications may therefore be associated with implantation failure and early pregnancy loss as well as with other endometrial pathologies.

Regulation of endometrial vascular remodelling: role of the vascular endothelial growth factor family and the angiopoietin–TIE signalling system

Angiogenesis, lymphangiogenesis and vascular maturation occur on a regular, physiological basis in human endometrium. These processes form part of a continuum of vascular remodelling involving numerous regulatory factors. Key factors include vascular endothelial growth factor (VEGF)A, VEGFC and VEGFD, and their associated receptors VEGFR1, VEGFR2 and VEGFR3. A second group of vascular regulatory proteins belongs to the angiopoietin (ANG)–TIE system. Although members of the VEGF family and the ANG–TIE system are represented in the endometrium, our understanding of how these different molecules interact to regulate remodelling of the blood and lymphatic vasculature present in the endometrium is still limited. A review of the current information is provided.

Current challenges in clinical management of endometrial cancer

Endometrial cancer remains a management challenge. Improved understanding of the mechanisms of carcinogenesis may enable better understanding of biologic behavior and guide therapy. Improvements in diagnostic imaging, radiation delivery systems, and systemic therapies potentially can improve outcomes while minimizing morbidity. Novel strategies for screening and prevention also hold promise for reducing incidence and mortality of this disease.