Stimulation of Angiotensin II Receptor Subtype 2 Reduces Preeclampsia-like Symptoms in a Mouse Model of Preeclampsia.

Angiotensin II (AngII) receptor subtype 1 (AT1R) is involved in the pathogenesis of preeclampsia (PE). Angiotensin II receptor subtype 2 (AT2R) can antagonize the effects of AT1R, but its effects during pregnancy are not known. We investigated the effect of AT2R on the pathogenesis of PE using a mouse model and recently developed AT2R agonist (compound 21 [C21]). Blastocysts collected from pregnant imprinting control region (ICR) mice were incubated with adenovirus containing the CD40L gene and transferred into the uterine horns of pseudo-pregnant ICR mice to express PE-like features. Osmotic pumps were placed subcutaneously on the dorsal side with C21 or saline. C21 reduced the plasma soluble fms-like tyrosine kinase 1 (sFlt-1) concentration, ameliorating hypertension. The splenic T and B cell profiles in model mice were analyzed by flow cytometry. The gated percentage of IFN-γ-positive Th cells was significantly increased and the percentage of plasma cells in B cells was significantly decreased; however, the percentages were not altered by C21. sFlt-1 and soluble endoglin concentrations in plasma were measured with an enzyme-linked immunosorbent assay, and sFlt-1 was reduced. C21 could become a candidate PE drug as it ameliorated the pathophysiology of PE as a result of decreased production of sFlt-1.

The Influence of Nicotine on Trophoblast-Derived Exosomes in a Mouse Model of Pathogenic Preeclampsia.

Preeclampsia (PE) is a serious complication of pregnancy with a pathogenesis that is not fully understood, though it involves the impaired invasion of extravillous trophoblasts (EVTs) into the decidual layer during implantation. Because the risk of PE is actually decreased by cigarette smoking, we considered the possibility that nicotine, a critical component of tobacco smoke, might protect against PE by modifying the content of exosomes from EVTs. We investigated the effects of nicotine on our PE model mouse and evaluated blood pressure. Next, exosomes were extracted from nicotine-treated extravillous trophoblasts (HTR-8/SVneo), and the peptide samples were evaluated by DIA (Data Independent Acquisition) proteomic analysis following nano LC-MS/MS. Hub proteins were identified using bioinformatic analysis. We found that nicotine significantly reduced blood pressure in a PE mouse model. Furthermore, we identified many proteins whose abundance in exosomes was modified by nicotine treatment of EVTs, and we used bioinformatic annotation and network analysis to select five key hub proteins with potential roles in the pathogenesis or prevention of PE. EVT-derived exosomes might influence the pathogenesis of PE because the cargo delivered by exosomes can signal to and modify the receiving cells and their environment.

HMGA1 Is a Potential Driver of Preeclampsia Pathogenesis by Interference with Extravillous Trophoblasts Invasion.

Preeclampsia (PE) is a serious disease that can be fatal for the mother and fetus. The two-stage theory has been proposed as its cause, with the first stage comprising poor placentation associated with the failure of fertilized egg implantation. Successful implantation and placentation require maternal immunotolerance of the fertilized egg as a semi-allograft and appropriate extravillous trophoblast (EVT) invasion of the decidua and myometrium. The disturbance of EVT invasion during implantation in PE results in impaired spiral artery remodeling. PE is thought to be caused by hypoxia during remodeling failure-derived poor placentation, which results in chronic inflammation. High-mobility group protein A (HMGA) is involved in the growth and invasion of cancer cells and likely in the growth and invasion of trophoblasts. Its mechanism of action is associated with immunotolerance. Thus, HMGA is thought to play a pivotal role in successful pregnancy, and its dysfunction may be related to the pathogenesis of PE. The evaluation of HMGA function and its changes in PE might confirm that it is a reliable biomarker of PE and provide prospects for PE treatment through the induction of EVT proliferation and invasion during the implantation.

Pathophysiology of Preeclampsia: The Role of Exosomes.

The pathogenesis of preeclampsia begins when a fertilized egg infiltrates the decidua, resulting in implantation failure (e.g., due to extravillous trophoblast infiltration disturbance and abnormal spiral artery remodeling). Thereafter, large amounts of serum factors (e.g., soluble fms-like tyrosine kinase 1 and soluble endoglin) are released into the blood from the hypoplastic placenta, and preeclampsia characterized by multiorgan disorder caused by vascular disorders develops. Successful implantation and placentation require immune tolerance to the fertilized egg as a semi-allograft and the stimulation of extravillous trophoblast infiltration. Recently, exosomes with diameters of 50-100 nm have been recognized to be involved in cell-cell communication. Exosomes affect cell functions in autocrine and paracrine manners via their encapsulating microRNA/DNA and membrane-bound proteins. The microRNA profiles of blood exosomes have been demonstrated to be useful for the evaluation of preeclampsia pathophysiology and prediction of the disease. In addition, exosomes derived from mesenchymal stem cells have been found to have cancer-suppressing effects. These exosomes may repair the pathophysiology of preeclampsia through the suppression of extravillous trophoblast apoptosis and promotion of these cells' invasive ability. Exosomes secreted by various cells have received much recent attention and may be involved in the maintenance of pregnancy and pathogenesis of preeclampsia.

Risk of Gynecologic Cancer as Second versus First Primary Cancer in Japan.

This study aimed to determine whether the risk conferred by gynecologic cancer (GC) as second primary cancer (SPC) differs from that associated with GC as first primary cancer (FPC). We investigated the correlations between FPC/SPC and the characteristics and prognoses of 1,645 GC patients (701 with cervical cancer [CC], 641 with endometrial cancer [EM], and 303 with ovarian cancer [OV]). The χ2 test and the Kaplan-Meier method were used to determine whether FPC/SPC and the characteristics and prognoses of GC patients. Of the SPC patients, 26 (3.7%) had CC, 53 (8.3%) had EM, and 31 (10.2%) had OV. The most common previous cancer type in SPC of GC patients was breast cancer, which was observed in 13 patients (50.0%) with CC, 23 (43.4%) with EM, and 16 (51.6%) with OV. In all patients with CC, EM, and OV as SPC, the stage was significantly associated with recurrence. There were no significant differences in the morbidity or mortality of CC, EM, or OV patients between those with FPC and those with SPC. The risk of SPC development in GC patients varied, ranging from 3.5% (CC) to 10.3% (OV) of patients.

The presence of chronic diseases contributes to the occurrence risk factors for gynecological cancers in Japan.

The aim of the present study was to determine whether chronic diseases (CD), such as hypertension, diabetes mellitus, dyslipidemia, heart diseases and cerebrovascular diseases, are occurrence risk factors and affect the survival of patients with gynecological cancers (GC). The correlations between CD and the characteristics and survival of 1,590 GC patients [685 with cervical cancer (CC), 613 with endometrial cancer (EM) and 292 with ovarian cancer (OV)] were investigated in the present study. Of the CD patients, 189 had CC (27.6%), 265 had EM (43.2%) and 72 had OV (24.7%). The incidence of CD increased with age in GC patients. The number of CD patients aged ≥70 years, was 8.6-fold higher in the CC group, 3.0-fold higher in the EM group, and 9.6-fold higher in the OV group compared with those aged <50 years. CD and excess body weight were associated with GC regardless of patient age. However, there was no correlation between CD and survival at any age in GC patients. These findings indicate that CD contribute to >24% of the occurrence risk factors in GC patients in Japan.

Pre-treatment psoas major volume is a predictor of poor prognosis for patients with epithelial ovarian cancer.

Low skeletal muscle mass (sarcopenia) is an important prognostic risk factor for the outcome of a variety of cancer types. The current study investigated whether skeletal muscle area (SMA), psoas area (PA) and psoas major volume (PV) are associated with progression-free survival (PFS) and overall survival (OS) in patients with epithelial ovarian cancer (OC). A total of 92 OC patients were enrolled in the present study. Pre-treatment with SMA and PA was assessed using computed tomography (CT) and PV was calculated using a three-dimensional-CT (3D-CT). The clinical factors associated with sarcopenia and prognosis were retrospectively evaluated. For all patients, the median PFS and OS were 19 and 32 months, respectively. Patients exhibiting lower PV (<195.6 cm3) had significantly poorer PFS and OS compared with patients exhibiting higher PV (≥195.6 cm3; P=0.018 and P=0.006), while those with low SMA (<92.92 cm2) had significantly worse OS than patients with higher SMA (≥92.92 cm2; P=0.030). PV was also demonstrated to be superior to SMA and PA in prognosis prediction. PV by 3D-CT can serve as an indicator of poor prognosis in patients with OC.

Clinical course in a patient with myopathic VLCAD deficiency during pregnancy with an affected baby.

Very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency is an autosomal recessive mitochondrial fatty acid oxidation disorder that manifests in three clinical forms: (a) severe, (b) milder, and (c) myopathic. Patients with the myopathic form present intermittent muscular symptoms such as myalgia, muscle weakness, and rhabdomyolysis during adolescence or adulthood. Here, the clinical symptoms and serum creatine kinase (CK) levels of a pregnant 31-year-old woman with the myopathic form of VLCAD deficiency were reduced during pregnancy. Clinical symptoms rarely appeared during pregnancy, although she had sometimes suffered from muscular symptoms before pregnancy. When ritodrine was administered for threatened premature labor at 35 weeks of gestation, her CK level was elevated to over 3900 IU/L. She delivered a full-term baby via cesarean section but suffered from muscle weakness with elevated CK levels soon after delivery. It has been reported that an unaffected placenta and fetus can improve maternal ß-oxidation during pregnancy. However, in our case, the baby was also affected by VLCAD deficiency. These suggest that the clinical symptoms of a woman with VLCAD deficiency might be reduced during pregnancy even if the fetus is affected with VLCAD deficiency.

Sarcopenia Is Not a Prognostic Factor of Outcome in Patients With Cervical Cancer Undergoing Concurrent Chemoradiotherapy or Radiotherapy.

BACKGROUND/AIM: The objective of this study was to determine if sarcopenia was a predictor of poor prognosis in patients with cervical cancer (CC) undergoing concurrent chemoradiation therapy (CCRT) or radiation therapy (RT). MATERIALS AND METHODS: A total of 236 patients with CC undergoing CCRT or RT were retrospectively examined. We determined if clinical characteristics and survival were correlated with pretreatment sarcopenia, measured as psoas muscle index (PI) or skeletal muscle index (SMI). RESULTS: Pretreatment PI and SMI were related to parametrial involvement with CC undergoing CCRT or RT (p=0.002, and, p=0.034, respectively). The median progression-free survival (PFS) and overall survival (OS) times in patients undergoing CCRT or RT were 29.0 and 34.5 months, respectively. Neither PI nor SMI were prognostic predictors in patients with CC undergoing CCRT or RT. CONCLUSION: Sarcopenia is not a predictive factor of outcome in patients with CC undergoing CCRT or RT.

Assessment of laparoscopic training for gynecological malignancies using Thiel-embalmed human cadavers.

The introduction of laparoscopic surgery has also been beneficial for patients with gynecological malignancies. In this respect, surgeons should receive related training in the context of human resource development. Hands-on training was introduced using Thiel-embalmed human cadavers (THCs) in 2014. To determine the usefulness of THCs, they were evaluated in terms of tissue color, consistency and operative tactility, among others, compared with in vivo laparoscopic training for gynecological malignancies. Hands-on training sessions using THCs were held for a total of 11 times at Ehime University Graduate School of Medicine between March 2014 and October 2017. Training on THCs included advanced laparoscopic procedures for radical hysterectomy type III. At the end of each training session, data were collected using a standardized, anonymous questionnaire termed the Likert scale. THCs ensured flexibility and plasticity of tissues and organs; therefore, the working space was similar to that in the living body under pneumoperitoneum. After analyzing the quality and consistency of tissue and organ color compared with in vivo conditions, most of the participants agreed or strongly agreed regarding the uterus, adnexa and ureter, but not regarding the large blood vessels. The highest scores were observed in the authenticity of the anatomical condition of each organ. Most participants strongly agreed that training using THCs would help improve their laparoscopic skills with a high level of satisfaction. Furthermore, most participants reported that they would recommend this training to other obstetrician-gynecologists. Laparoscopic training for gynecological malignancies using THCs was comparable to the in vivo conditions in terms of surgical view and operative tactility. Therefore, THCs may be an excellent training tool for improving laparoscopic surgical skills for gynecological malignancies.

The Influence of Chemotherapy-Induced Peripheral Neuropathy on Quality of Life of Gynecologic Cancer Survivors.

OBJECTIVE: The aim of this observational study was to investigate correlations between long-term chemotherapy-induced peripheral neurotoxicity (CIPN) and quality of life (physical well-being, social well-being, emotional well-being, and functional well-being [FWB]) among survivors of gynecologic cancer (GC). METHODS: We aimed to assess the correlation of quality of life and long-term CIPN with the temporal change in recurrence-free GC survival. Questionnaire responses and clinical data of 259 GC survivors were collected and assessed according to treatment received. The χ test was used to determine the significance of correlations. RESULTS: Of 165 evaluable patients treated by chemotherapy, 36 patients (21.8%) developed CIPN of Common Toxicity Criteria for Adverse Events grade 1 or higher during the study. Chemotherapy-induced peripheral neurotoxicity had significantly improved over time in the domain of FWB at 61 months or more after the end of chemotherapy (posttreatment 4) among GC survivors (P = 0.003). Furthermore, CIPN treated by more than 6 courses of the paclitaxel and carboplatin regimen among GC survivors showed significant improvement over time in the emotional well-being domain at 25 to 60 months and 61 months or more after the end of chemotherapy (posttreatments 3 and 4) (P = 0.037 and P = 0.023) and in FWB at posttreatment 4 (P < 0.001). CONCLUSIONS: Emotional and functional domains of CIPN improved over time among GC survivors treated by more than 6 courses of the paclitaxel and carboplatin regimen. Based on these results, further research is required to identify additional preventative or curative approaches.

Extranuclear Translocation of High-Mobility Group A1 Reduces the Invasion of Extravillous Trophoblasts Involved in the Pathogenesis of Preeclampsia: New Aspect of High-Mobility Group A1.

OBJECTIVE: High-mobility group A1 (HMGA1) protein is known to express in trophoblast; however, the role of migration has not been reported to date. In this study, we investigated the role of HMGA1 on the pathogenesis of preeclampsia using immortalized human trophoblast cell (HTR-8/SVneo). MATERIALS AND METHODS: We investigated HMGA1 expression in cytotrophoblasts derived from our preeclampsia model mouse, the CD40L mouse, using immunofluorescence. Wound healing and transwell migration assays were also performed using HTR-8/SVneo (extravillous trophoblast) cells transfected with DNA or siRNA of HMGA1. The effect of extranuclear translocation of HMGA1 on the migration of extravillous trophoblastic cells was evaluated using deoxycholic acid (DCA). RESULTS: HMGA1 was expressed exclusively in the nuclei of trophoblasts derived from control mice; cytoplasmic expression was observed only in CD40L mice with preeclampsia. Furthermore, overexpression of HMGA1 in the nuclei of HTR-8/SVneo cells stimulated cell proliferation and migration. Translocation of nuclear HMGA1 to cytoplasm treated with DCA reduced cell migration. CONCLUSIONS: Collectively, these findings demonstrate that proper subcellular localization of HMGA1 is important for its function in trophoblast cells, and suggest that aberrant cytoplasmic expression of HMGA1 contributes to the pathogenesis of preeclampsia through impairment of trophoblast migration.

Clinical investigation of the safety and efficacy of a cervical intraepithelial neoplasia treatment using a hyperthermia device that uses heat induced by alternating magnetic fields.

Multiple techniques have been used for the conservative treatment of high-grade cervical intraepithelial neoplasia (HG-CIN) in women of fertile age. Conization has been associated with stenosis of the cervix and a decrease in cervical mucus secretion, in addition to the increase in the risk of cervical canal shortening and problems during the perinatal period, including premature birth and premature rupture of membranes. Although the laser transpiration technique does not cause shortening of the cervical canal, it is associated with the recurrent risk of deep residual disease. The present study aimed to investigate the therapeutic safety and efficacy of the therapy performed using the transaction magnetic field induction heating device, AMTC400, in fertile patients with HG-CIN (excluding carcinoma in situ). Four premenopausal patients with CIN3 and high-risk human papilloma virus (HPV)-positive were treated using an AMTC400. Chronological colposcopic findings, high-risk HPV, final histological findings with conization and follow-up data were evaluated. All the treatments were successfully performed on the in-patients without anesthesia. Intra- and postoperative complications included minor pain and bleeding in all cases. Two of the cases (50%) were high-risk HPV-negative following the treatments. All cases exhibited a change in the observed color (to white), and subsequent epithelization following treatment. Although cytological analysis at 5 weeks following the treatment confirmed the cases were negative for intraepithelial lesions and malignancies, a definitive histology with conization 6 weeks following the treatment confirmed CIN1 and koilocytosis in all cases. The assessment of treatment effectiveness was determined as a moderate improvement in all cases. In conclusion, thermotherapy applied using AMTC400 represented a safe and effective treatment for HG-CIN in women of fertile age. However, additional improvements associated with the site of puncture needles are required. Further studies are required to confirm the long-term efficacy and reproductive outcomes.

Immune activation during the implantation phase causes preeclampsia-like symptoms via the CD40-CD40 ligand pathway in pregnant mice.

The CD40 ligand (CD40L) is expressed by T cells and has a critical role in immune system regulation. Interventions targeting CD40L interactions following embryo implantation represent an approach to preventing preeclampsia (PE). To better understand the role of CD40L in PE, we developed a PE mouse model in which we examined how CD40L-induced immune activation affects embryo implantation. Blastocysts were incubated with CD40L-expressing adenovirus and then were transferred into the uterine horns of pseudopregnant ICR mice. Histology, biochemistry and flow cytometry experiments were performed to examine the characteristics of the mouse model. In early pregnancy, decidualization and spiral artery remodeling were reduced in CD40L-transfected mice (CD40L mice) compared with control mice. Hematoxylin-eosin (HE) staining revealed hemorrhaging and excess fibrin deposition at the labyrinth layer-junctional zone interface of the placenta, and PAS staining demonstrated prominent focal and segmental sclerosis with collapsed glomerular capillaries in the kidneys of the CD40L mice. Flow cytometry data showed that interferon-γ production derived from CD4(+) T cells was elevated in the splenic cells of CD40L mice. Blood pressure (measured by the tail-cuff method) and urine albumin concentrations were significantly increased in CD40L mice compared with control mice. Furthermore, the plasma concentrations of soluble Flt-1 and soluble endoglin were increased in CD40L mice, as occurs in human patients with PE. Thus, CD40L-induced T-helper cell type 1 differentiation during embryo implantation may have a critical role in the pathogenesis of a PE-like presentation in a novel mouse model of PE.

Chick embryos can form teratomas from microinjected mouse embryonic stem cells.

We examined whether chick embryos are a suitable experimental model for the evaluation of pluripotency of stem cells. Mouse embryonic stem cells (mESCs) expressing the reporter gene, LacZ or GFP were injected into the subgerminal cavity of blastoderms (freshly oviposited) or the marginal vein of chick embryos (2 days of incubation). Injected mESCs were efficiently incorporated into the body and extra-embryonic tissues of chick embryos and formed small clusters. Increased donor cell numbers injected were positively associated with the efficiency of chimera production, but with lower viability. A single mESC injected into the blastoderm proliferated into 34.7 ± 3.8 cells in 3 days, implying that the chick embryo provides an optimal environment for the growth of xenogenic cells. In the embryo body, mESCs were interspersed as small clustered chimeras in various tissues. Teratomas were observed in the yolk sac and the brain with three germ layers. In the yolk sac, clusters of mESCs gradually increased in volume and exhibited varied morphology such as a water balloon-like or dark-red solid mass. However, mESCs in the brain developed into a large soft tissue mass of whitish color and showed a tendency to differentiate into ectodermal lineage cells, including primitive neural ectodermal and neuronal cells expressing the neurofilament protein. These results indicate that chick embryos are useful for the teratoma formation assays of mESCs and have a broad-range potential as an experimental host model.

Stromal Cell-Derived Factor-1α Plays a Crucial Role Based on Neuroprotective Role in Neonatal Brain Injury in Rats.

Owing to progress in perinatal medicine, the survival of preterm newborns has markedly increased. However, the incidence of cerebral palsy has risen in association with increased preterm birth. Cerebral palsy is largely caused by cerebral hypoxic ischemia (HI), for which there are no effective medical treatments. We evaluated the effects of stromal cell-derived factor-1α (SDF-1α) on neonatal brain damage in rats. Left common carotid (LCC) arteries of seven-day-old Wistar rat pups were ligated, and animals were exposed to hypoxic gas to cause cerebral HI. Behavioral tests revealed that the memory and spatial perception abilities were disturbed in HI animals, and that SDF-1α treatment improved these cognitive functions. Motor coordination was also impaired after HI but was unimproved by SDF-1α treatment. SDF-1α reduced intracranial inflammation and induced cerebral remyelination, as indicated by the immunohistochemistry results. These data suggest that SDF-1α specifically influences spatial perception abilities in neonatal HI encephalopathy.

Nitric oxide and reactive oxygen species in the pathogenesis of preeclampsia.

Preeclampsia (PE) is characterized by disturbed extravillous trophoblast migration toward uterine spiral arteries leading to increased uteroplacental vascular resistance and by vascular dysfunction resulting in reduced systemic vasodilatory properties. Its pathogenesis is mediated by an altered bioavailability of nitric oxide (NO) and tissue damage caused by increased levels of reactive oxygen species (ROS). Furthermore, superoxide (O2-) rapidly inactivates NO and forms peroxynitrite (ONOO-). It is known that ONOO- accumulates in the placental tissues and injures the placental function in PE. In addition, ROS could stimulate platelet adhesion and aggregation leading to intravascular coagulopathy. ROS-induced coagulopathy causes placental infarction and impairs the uteroplacental blood flow in PE. The disorders could lead to the reduction of oxygen and nutrients required for normal fetal development resulting in fetal growth restriction. On the other hand, several antioxidants scavenge ROS and protect tissues against oxidative damage. Placental antioxidants including catalase, superoxide dismutase (SOD), and glutathione peroxidase (GPx) protect the vasculature from ROS and maintain the vascular function. However, placental ischemia in PE decreases the antioxidant activity resulting in further elevated oxidative stress, which leads to the appearance of the pathological conditions of PE including hypertension and proteinuria. Oxidative stress is defined as an imbalance between ROS and antioxidant activity. This review provides new insights about roles of oxidative stress in the pathophysiology of PE.

Concurrent chemoradiotherapy with nedaplatin in patients with stage IIA to IVA cervical carcinoma.

The present study aimed to evaluate the efficacy and toxicities of nadaplatin-based concurrent chemoradiotherapy (CCRT) in patients with stage IIA to IVA cervical carcinoma. Patients with an International Federation of Gynecology and Obstetrics (FIGO) stage IIA to IVA cervical carcinoma were treated with nadaplatin-based CCRT, using high-dose rate intracavitary brachytherapy (HDR-ICBT) or radiotherapy (RT) alone, in patients with FIGO stage IIA to IVA cervical carcinoma. CCRT with nedaplatin (80 mg/m2) was administered on Days 1 and 29. The records of 17 women treated either with nadaplatin-based CCRT using HSR-ICBT (n=8) or RT alone (n=9), for stage IIA to IVA cervical carcinoma were retrospectively reviewed. The activity and toxicity were compared in the two treatment groups. Progression-free survival (PFS) and overall survival (OS) were the main endpoints. The 5-year overall survival rates in the CCRT and RT groups were 68.6 and 77.8%, respectively. The median OS of the CCRT and RT groups was 38.5 and 27.3 months, respectively. There was no significant difference in either PFS (P=0.618) or OS (P= 0.231). The most common grade 3-4 or higher toxicities in the CCRT groups were leuko-/neutropenia (37.5%). The frequency of acute grade 3-4 toxicity was higher in the CCRT compared to the RT group. However, no statistically significant difference was observed. Nedaplatin-based CCRT was safely performed. Although the prognosis of patients with FIGO stage IIA to IVA cervical carcinoma was not significantly improved, fewer distant relapses were observed in this treatment. Consequently, nedaplatin-based CCRT may be considered as a potential alternative to cisplatin-based CCRT in this patient population.

Estrogen and progesterone play pivotal roles in endothelial progenitor cell proliferation.

BACKGROUND: It has been previously suggested that angiogenesis occurs during the menstrual cycle. Moreover, a rise in uterine blood flow is largely maintained by vasodilatation and substantial increases in angiogenesis. It is known that estradiol (E2) and progesterone (P4) are involved in angiogenesis. Recently, endothelial progenitor cells (EPCs) were found to be involved in neovascularization; however, their roles in uterine neovascularization have not been well characterized. We hypothesized that E2- or P4-mediated EPC proliferation plays important roles in uterine neovascularization during the menstrual cycle. METHODS: The number of EPCs in peripheral blood from subjects in the menstrual phase (n=12), follicular phase (n=8), and luteal phase (n=16), was measured using flow cytometry. Peripheral blood mononuclear cells (PBMCs) were cultured for seven days with or without 17beta-estradiol (E2beta) or P4, followed by assessment of EPC proliferation based upon the uptake of acetylated low density lipoprotein (LDL) and lectin. The expression of estrogen receptor (ER) or progesterone receptor (PR) in EPCs was also evaluated using real-time PCR. RESULTS: E2beta and P4 significantly increased the proliferation of EPCs derived from the peripheral blood of subjects in menstrual phase, but not subjects in the luteal phase. In addition, the expression level of ERalpha was markedly higher than ERbeta in EPCs derived from women in menstrual phase. CONCLUSIONS: EPC proliferation is induced during the menstrual phase and proliferation can be affected by estrogen through ERalpha activation.