Fetal Vascular Endothelium Research Articles

A novel technique to estimate intravillous fetal vasculature on routine placenta histologic sections

Placental histopathologic lesions are dichotomized into “present” or “absent” and have limited inter-rater reliability. Continuous metrics are needed to characterize placental health and function. Tissue sections (N = 64) of human placenta were stained with CD34 antibody and hematoxylin. Proportion of the villous space occupied by fetal vascular endothelium (%FVE; pixels positive for CD34/total pixels) was evaluated for effect sizes associated with pregnancy outcomes, smoking status, and subtypes of lesions (n = 30). Time to fixation>60 min significantly increased the quantification. Large effect sizes were found between %FVE and both preterm birth and intrauterine growth restriction. These results demonstrate proof-of-concept for this vascular estimation.

Deletion of fetoplacental Fshr inhibits fetal vessel angiogenesis in the mouse placenta.

It has been shown in both human and mouse placentas that follicle stimulating hormone receptor (FSHR) is expressed in fetal vascular endothelium. There are conflicting reports, however, on the role of FSH to stimulate angiogenesis in vitro in cultured endothelial cells from umbilical veins. Therefore, in this study we undertook an in vivo approach utilizing Fshr null mice to definitively address this question. In the context where all pregnant dams have identical Fshr genotypes, we generated fetuses and associated fetal portions of placenta that were Fshr wt or Fshr null and analyzed angiogenesis within the placental labyrinths. Quantitative morphometric analyses of placentas obtained at mid-gestation revealed that the percentage of the placenta composed of labyrinth is significantly decreased in Fshr null placentas relative to wt placentas. Furthermore, data presented demonstrate that within the Fshr null labyrinths, fetal vessel angiogenesis was significantly reduced relative to wt labyrinths. The results obtained with this combination of in vivo and genetic approaches conclusively demonstrate that signaling through endothelial FSHR does indeed stimulate angiogenesis and that placental Fshr is essential for normal angiogenesis of the fetal placental vasculature.

Hepcidin, an Iron Regulatory Hormone of Innate Immunity, is Differentially Expressed in Premature Fetuses with Early-Onset Neonatal Sepsis.

Hepcidin, a mediator of innate immunity, binds the iron exporter ferroportin, leading to functional hypoferremia through intracellular iron sequestration. We explored hepcidin-ferroportin interactions in neonates clinically diagnosed with early-onset neonatal sepsis (EONS). Hepcidin and interleukin (IL)-6 were quantified by enzyme-linked immunosorbent assay (ELISA) in 92 paired cord blood-maternal blood samples in the following groups: "Yes" EONS (n = 41, gestational age [GA] 29 ± 1 weeks) and "No" EONS (n = 51, GA 26 ± 1 weeks). Placental hepcidin and ferroportin expression were evaluated by immunohistochemistry and real-time-polymerase chain reaction (RT-PCR). Liver hepcidin and ferroportin expression patterns were ascertained in autopsy specimens of neonates (n = 8) who died secondary to culture-proven sepsis. Cord blood hepcidin was significantly elevated (GA corrected, p = 0.018) and was positively correlated with IL-6 (r = 0.379, p = 0.001) in EONS. Hepcidin localized at syncytiotrophoblast and fetal vascular endothelium. Placental ferroportin, but not hepcidin mRNA correlated with cord blood hepcidin levels (r = 0.46, p = 0.039) and funisitis severity (r = 0.50, p = 0.018). Newborns who died from sepsis (n = 4) had higher hepatic hepcidin and iron sequestration, but lower ferroportin staining than those who died of nonsepsis causes (n = 4). Premature fetuses with EONS have elevated circulating hepcidin, likely related to lower placenta and liver ferroportin expression. Fetal hepcidin-ferroportin interaction appears to play a role in EONS pathophysiology independent of maternal response to intrauterine inflammation.

The expression and localization of the human placental prorenin/renin-angiotensin system throughout pregnancy: Roles in trophoblast invasion and angiogenesis?

The renin-angiotensin system (RAS) is thought to regulate placentation, however, the expression and localization of RAS pathways in early gestation human placenta is not known. Here we describe the expression of prorenin (REN), (pro)renin receptor (ATP6AP2), angiotensinogen (AGT), angiotensin-converting enzyme 1 and 2 (ACE; ACE2), angiotensin II type 1 and 2 receptors (AGTR1; AGTR2) and angiotensin 1–7 receptor (MAS1), as well as the angiogenic factor, vascular endothelial growth factor (VEGF), and transforming growth factor-β1 (TGF-β1), in early gestation (6–16 weeks) and term (>37 weeks) human placentae. We also describe the location of all of the key RAS proteins in the early gestation placentae. The highest levels of REN, ATP6AP2, AGT, AGTR1 and ACE2 mRNAs were found in early gestation, whereas ACE1 mRNA was highest at term. AGTR2 and MAS1 mRNA expression were low to undetectable in all samples. REN, ATP6AP2 and AGTR1 mRNA levels were correlated with VEGF expression, but not with TGF-β1 mRNA. In early gestation placentae, prorenin, (pro)renin receptor and the angiotensin II type 1 receptor (AT1R) were localized to extravillous trophoblast cells, suggesting they play a key role in trophoblast migration. ACE2 in syncytiotrophoblasts could regulate release of Ang 1-7 into the maternal circulation contributing to the vasodilation of the maternal vasculature. ACE was only found in fetal vascular endothelium and may specifically target the growing fetal placental vessels. Because REN, ATP6AP2 and AGTR1 show strong correlations with expression of VEGF this pathway is likely to be important in placental angiogenesis.

Trends in vascular pharmacology research in the Department of Pharmacology and Clinical Pharmacology, Faculty of Medicine, Comenius University, Bratislava

Research in the Department of Pharmacology started to focus intensively on fetal circulation in the 60s. Results of experiments contributed to clarification of the conversion of fetal circulation type to the adult type: the mechanism of the ductus arteriosus closure, examination of fetal and neonatal pulmonary vessel responses. In the early 80s, increased attention was dedicated to fetal vascular endothelium, later on to vascular reactivity in relation to the endothelium in adult animals. We developed original models of vascular endothelial damage using the perfusion method (repeated vasoconstrictive stimuli, deendothelization by air bubbles). We developed a new technique for in vitro endothelial loss quantification on Millipore filters. Under in vitro conditions, the protective effects of sulodexide and pentoxifylline on vascular endothelium were evaluated. In recent years were studied protective effects of selected substances in vivo in models of endothelial damage (e.g. stress, toxic tissue damage, diabetes mellitus, hypertension). The role of potassium channels in the hypertension model was studied in cooperation with the Czech Academy of Sciences. Assessment of vascular reactivity in the diabetic model was significantly improved by computer. In addition to experimental work, the department is solving problems of clinical pharmacology – especially drug risk evaluation (non-steroidal anti-inflammatory drugs). Recently, we have dealt with pharmacoepidemiological studies in geriatric patients and with cardiovascular risk of NSAIDs in relation to pharmacotherapy. The results of these studies may be an impulse for targeted problem solving in our experiments.

Regulation of Expression and Localisation of the Na +/H + Exchanger (NHE) 3 and the NHE Regulatory Factor 2 in Baboon Placental Syncytiotrophoblast by Oestrogen

Our understanding of the regulation of the expression of the sodium hydrogen exchangers (NHE) and their regulatory factors (NHERF), which play important roles in fetal–placental homeostasis, is incomplete. We previously showed that the expression and localisation of NHE3 and NHERF2 in the juxtanuclear compartment of the placental syncytiotrophoblast were markedly decreased between mid and late baboon pregnancy. In the current study, immunocytochemical fluorescence localisation and level of NHE3/NHE1 and NHERF1/NHERF2 proteins were determined in late gestation in baboons untreated or treated throughout the second half of gestation with an aromatase inhibitor CGS 20267 alone (reduced oestrogen levels by >95%) or with oestradiol to determine whether oestrogen regulated antiporter developmental expression. The immunocytochemical expression of NHE3 and NHERF2 in the juxtanuclear compartment was minimal in baboons untreated or treated with CGS 20267 plus oestradiol (i.e. oestrogen-replete) but extensive in oestrogen-suppressed animals. Moreover, the abundant expression of NHERF2 in fetal vascular endothelium of oestrogen-replete baboons was decreased in oestrogen-suppressed animals. In contrast, expression and localisation of NHE1 and NHERF1 in the placental syncytiotrophoblast were not altered by oestrogen deprivation in baboons. Based on our current and previous findings, we propose that oestrogen plays an important role in regulating localisation and expression of components of the NHE system within and consequently development and function of the primate placental syncytiotrophoblast.

Developmental Regulation of the Sodium/Hydrogen Ion Exchangers and Their Regulatory Factors in Baboon Placental Syncytiotrophoblast

Although Na+/H+ exchange is important to maintenance of pH and volume and thus placental-fetal homeostasis, regulation of the Na+/H+ exchange system is incompletely understood. We previously showed that Na+/H+ exchanger (NHE)1 and -3 and their regulatory factors NHERF1 and -2 were expressed in human and nonhuman primate placenta. Our laboratories have also shown that estrogen regulates key aspects of primate placental function and development including the 11beta-hydroxysteroid dehydrogenase enzymes controlling cortisol metabolism. Therefore, it is possible that localization and/or expression of components of the syncytiotrophoblast NHE system are also estrogen dependent. As a first step in testing this possibility, the current study compared the immunocytochemical localization and level of NHE1, NHE3, NHERF1, and NHERF2 in baboon placentas obtained at mid- (d 100) and late gestation (d 165; term = d 184). NHE3 and NHERF2 were abundantly expressed at midgestation and localized to the cytoplasm and juxtanuclear compartment but were not detected in the microvillus membrane. By late gestation, NHE3 and NHERF2 expression were markedly reduced in the juxtanuclear compartment but not the cytoplasm. NHERF2 was also abundantly expressed in fetal vascular endothelium in which levels, as assessed by immunoblot exhibited a 3-fold developmental increase. In contrast, levels of NHE1 and NHERF1, which were abundantly expressed in and localized almost exclusively to syncytiotrophoblast microvillus membrane, were similar at mid- and late gestation. We conclude that the subcellular distribution and levels of key components of the Na+/H+ system in the baboon syncytiotrophoblast are developmentally regulated.

Cerebellar anomalies in congenital murine toxoplasmosis.

Gravid Nya:NYLAR mice, infected with Toxoplasma gondii on gestation day 7, experienced embryo resorptions, abortions, stillbirths, and a reduction in average litter size by one-third. Postnatally, all congenitally infected pups showed growth retardation, cachexia, and hind limb weakness. Some pups developed necrotic petechiae on the ears and tail, and a blood-tinged nasal discharge. Coronal sections of the cerebellum at age 1 month revealed developmental abnormalities including: persistence of remnants of an external granular layer; fragmented and disoriented Bergmann glial foot processes; numerous ectopic granule cells stranded in the molecular layer; focal disorganization and edema of the Purkinje cell layer; and thinning of the internal granular layer. Our working hypothesis is that the cerebellar anomalies originated with parasite invasion of the fetal vascular endothelium leading to vasculitis and microcirculatory dysfunction, perivascular edema, perfusion impairment, and tissue anoxia. In the cerebellar folia, the cellular migration defects are attributed to edema-induced swelling and fragmentation of the Bergmann glial foot processes that guide migrating neurons, whereas the focal loss of Purkinje and granule cells is ascribed to hypoxia-ischemia. Although Toxoplasma cysts were detected in the cerebellum, morphologic evidence of parasite association with neuropathology was not obtained.

The relation between intercellular adhesion molecule-1 is expressed on fetal vascular endothelium and the onset of preeclampsia

International Journal of Gynecology & ObstetricsVolume 70, Issue S5 p. E32-E32 Free communication preeclampsia investigation The relation between intercellular adhesion molecule-1 is expressed on fetal vascular endothelium and the onset of preeclampsia R. Oyama, R. OyamaSearch for more papers by this authorS. Chizuko, S. ChizukoSearch for more papers by this authorM. Morimasa, M. MorimasaSearch for more papers by this authorK. Teruo, K. TeruoSearch for more papers by this author R. Oyama, R. OyamaSearch for more papers by this authorS. Chizuko, S. ChizukoSearch for more papers by this authorM. Morimasa, M. MorimasaSearch for more papers by this authorK. Teruo, K. TeruoSearch for more papers by this author First published: 11 December 2003 https://doi.org/10.1016/S0020-7292(00)82443-1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume70, IssueS52000Pages E32-E32 RelatedInformation

The Localization and Expression of the Renin–angiotensin System in the Human Placenta Throughout Pregnancy

All the components of the renin-angiotensin system (RAS), including the AT1receptor, have previously been shown to be present in the human term placenta. However, the presence of the RAS components has not been fully investigated in the human placenta throughout pregnancy. The aim of this study was to examine the localization of the angiotensin receptors AT1and AT2using immunocytochemistry and the expression of prorenin, angiotensinogen and the AT1and AT2receptor mRNA using RT-PCR in the human placenta in the first, second and third trimesters of pregnancy. Localization of the AT1receptor was shown throughout gestation in the syncytiotrophoblast, cytotrophoblast, Hofbauer cells and the fetal vascular endothelium. Expression of mRNA for prorenin, angiotensinogen and the AT1receptor was shown in the placenta throughout gestation. However, localization or mRNA expression of the AT2receptor was not detected in any of the placental samples studied. These results clearly show the expression of a majority of the components of the RAS in the placenta from early gestation onwards. Therefore, these results suggest that the RAS may have a role in the human placenta throughout gestation.

Increase in expression and activity of thrombomodulin in term human syncytiotrophoblast microvilli

A comparative study of thrombomodulin (TM), a potent natural anticoagulant, was performed in first trimester and term human placentae. Immunoreactive TM was observed on fetal vascular endothelium and syncytiotrophoblast at both gestational ages. Staining was stronger in term than in early placentae, particularly along the microvillous apical membrane of the syncytiotrophoblast. Similarly, a higher level of TM mRNA was detected by RT-PCR ( P<0.02) and Northern blot analysis in extracts of whole term placentae. The localization of TM on syncytial microvilli was confirmed by electron microscopy after immunogold labelling. When isolated microvilli were compared at both gestational ages; a significant 2.3-fold increase in TM protein was observed in term microvilli as compared to first trimester microvilli by Western blot analysis ( P<0.005) and ELISA ( P<0.05). This higher level of TM in term microvilli was associated with an increase in its ability to activate protein C, from 3.7 ± 1.2 to 8.7 ± 4.2 mOD/min/μg protein ± s.d. ( P<0.01) in first trimester and term microvilli, respectively. The modulation of biologically active TM at the syncytial membrane exposed to maternal blood according to the length of gestation suggests that TM may be involved both in maternal haemostasis within the intervillous spaces, and also in the trophoblast differentiation process.

Human fetal endothelial cells acquire zinc(II) from both the protein bound and nonprotein bound pools in serum.

To help determine physiologically important routes by which zinc (Zn) is acquired by human fetal vascular endothelium, the authors incubated cultured umbilical vein endothelial cells with 65Zn(II)-tracer labeled human fetal whole serum, ultrafiltrate (containing low molecular mass serum zinc complexes), and dialyzed serum (containing protein-bound zinc). Zinc from whole serum and from both serum fractions entered a rapidly labeled cellular compartment, removable by edetic acid (EDTA), representing Zn bound to the outside cell surface, and accumulatively, an EDTA-resistant compartment-probably largely internalized Zn. Entry of Zn into the EDTA-resistant pool from both serum fractions was strongly temperature-dependent, and was not via the EDTA-sensitive pool. Entry from the ultrafiltrate was resolvable into high affinity saturable, and non- (or hardly-) saturable components. Transfer from the dialyzed serum fraction was not significantly saturable, but only partially accounted for by nonspecific pinocytosis. Thus, Zn is obtained by fetal vascular endothelium partly from low molecular mass serum species, probably through at least one carrier-mediated membrane transport system; but also from Zn complexed with serum protein, via at least one metabolism-related route.