The effect of fertility treatment and socioeconomic status on neonatal and post-neonatal mortality in the United States

OBJECTIVE

To determine the association between fertility treatment, socioeconomic status (SES), and neonatal and post-neonatal mortality.

STUDY DESIGN

Retrospective cohort study of all births (19,350,344) and infant deaths from 2014-2018 in the United States. The exposure was mode of conception-spontaneous vs fertility treatment. The outcome was neonatal (<28d), and post-neonatal (28d-1y) mortality. Multivariable logistic models were stratified by SES.

RESULT

The fertility treatment group had statistically significantly higher odds of neonatal mortality (high SES OR 1.59; CI [1.5, 1.68], low SES OR 2.11; CI [1.79, 2.48]) and lower odds of post-neonatal mortality (high SES OR 0.87, CI [0.76, 0.996], low SES OR 0.6, CI [0.38, 0.95]). SES significantly modified the effect of ART/NIFT on neonatal and post-neonatal mortality.

CONCLUSIONS

Fertility treatment is associated with higher neonatal and lower post-neonatal mortality and SES modifies this effect. Socioeconomic policies and support for vulnerable families may help reduce rates of infant mortality.

Perinatal Azithromycin Provides Limited Neuroprotection in an Ovine Model of Neonatal Hypoxic-Ischemic Encephalopathy

BACKGROUND

Hypoxic-ischemic brain injury/encephalopathy affects about 1.15 million neonates per year, 96% of whom are born in low- and middle-income countries. Therapeutic hypothermia is not effective in this setting, possibly because injury occurs significantly before birth. Here, we studied the pharmacokinetics, safety, and efficacy of perinatal azithromycin administration in near-term lambs following global ischemic injury to support earlier treatment approaches.

METHODS

Ewes and their lambs of both sexes (n=34, 141-143 days) were randomly assigned to receive azithromycin or placebo before delivery as well as postnatally. Lambs were subjected to severe global hypoxia-ischemia utilizing an acute umbilical cord occlusion model. Outcomes were assessed over a 6-day period.

RESULTS

While maternal azithromycin exhibited relatively low placental transfer, azithromycin-treated lambs recovered spontaneous circulation faster following the initiation of cardiopulmonary resuscitation and were extubated sooner. Additionally, peri- and postnatal azithromycin administration was well tolerated, demonstrating a 77-hour plasma elimination half-life, as well as significant accumulation in the brain and other tissues. Azithromycin administration resulted in a systemic immunomodulatory effect, demonstrated by reductions in proinflammatory IL-6 (interleukin-6) levels. Treated lambs exhibited a trend toward improved neurodevelopmental outcomes while histological analysis revealed that azithromycin supported white matter preservation and attenuated inflammation in the cingulate and parasagittal cortex.

CONCLUSIONS

Perinatal azithromycin administration enhances neonatal resuscitation, attenuates neuroinflammation, and supports limited improvement of select histological outcomes in an ovine model of hypoxic-ischemic brain injury/encephalopathy.

Effect of Clemastine on Neurophysiological Outcomes in an Ovine Model of Neonatal Hypoxic-Ischemic Encephalopathy

Originally approved by the U.S. Food and Drug Administration (FDA) for its antihistamine properties, clemastine can also promote white matter integrity and has shown promise in the treatment of demyelinating diseases such as multiple sclerosis. Here, we conducted an in-depth analysis of the feasibility, safety, and neuroprotective efficacy of clemastine administration in near-term lambs (n = 25, 141-143 days) following a global ischemic insult induced via an umbilical cord occlusion (UCO) model. Lambs were randomly assigned to receive clemastine or placebo postnatally, and outcomes were assessed over a six-day period. Clemastine administration was well tolerated. While treated lambs demonstrated improvements in inflammatory scores, their neurodevelopmental outcomes were unchanged.

Fertility treatment increases the risk of preterm birth independent of multiple gestations

Objective

To investigate the complex interplay between fertility treatment, multiple gestations, and prematurity.

Design

Retrospective cohort study linking the national Center for Disease Control and Prevention infant birth and death data from 2014 to 2018.

Setting

National database from Center of Disease Control and Prevention.

Patients

In total, 19,454,155 live-born infants with gestational ages 22-44 weeks, 114,645 infants born using non IVF fertility treatment (NIFT), and 179,960 via assisted reproductive technology (ART).

Intervention

Noninvasive fertility treatment or ART vs. spontaneously conceived pregnancies.

Main Outcome Measures

The main outcome assessed was prematurity. Formal mediation analysis was conducted to calculate the percentage mediated by multiple gestations.

Results

Newborns born using NIFT or ART compared with those with no fertility treatment had a higher incidence of multiple gestation (no fertility treatment = 3.0%; NIFT = 24.7%; ART = 32.7%; P<.001) and prematurity (no fertility treatment = 11.2%; NIFT = 23.4%; ART = 28.4%; P<.001). Mediation analysis demonstrates that 76.8% (95% confidence interval [CI], 75.2%-78.1%) of the effect of NIFT on prematurity was mediated through multiple gestations. Similarly, 71.2% (95% CI, 70.8%-72.7%) of the effect of ART on prematurity is mediated through multiple gestation. However, the direct effect of NIFT on prematurity is 20.4% (95% CI, 19.0%-22.0%). The direct effect of ART was 24.7% (95% CI, 23.7%-25.6%).

Conclusion

A significant proportion of prematurity associated with fertility treatment is mediated by the treatment itself, independent of multiple gestations.

Comparing the efficacy in reducing brain injury of different neuroprotective agents following neonatal hypoxia-ischemia in newborn rats: a multi-drug randomized controlled screening trial

Intrapartum hypoxia-ischemia leading to neonatal encephalopathy (NE) results in significant neonatal mortality and morbidity worldwide, with > 85% of cases occurring in low- and middle-income countries (LMIC). Therapeutic hypothermia (HT) is currently the only available safe and effective treatment of HIE in high-income countries (HIC); however, it has shown limited safety or efficacy in LMIC. Therefore, other therapies are urgently required. We aimed to compare the treatment effects of putative neuroprotective drug candidates following neonatal hypoxic-ischemic (HI) brain injury in an established P7 rat Vannucci model. We conducted the first multi-drug randomized controlled preclinical screening trial, investigating 25 potential therapeutic agents using a standardized experimental setting in which P7 rat pups were exposed to unilateral HI brain injury. The brains were analysed for unilateral hemispheric brain area loss after 7 days survival. Twenty animal experiments were performed. Eight of the 25 therapeutic agents significantly reduced brain area loss with the strongest treatment effect for Caffeine, Sonic Hedgehog Agonist (SAG) and Allopurinol, followed by Melatonin, Clemastine, ß-Hydroxybutyrate, Omegaven, and Iodide. The probability of efficacy was superior to that of HT for Caffeine, SAG, Allopurinol, Melatonin, Clemastine, ß-hydroxybutyrate, and Omegaven. We provide the results of the first systematic preclinical screening of potential neuroprotective treatments and present alternative single therapies that may be promising treatment options for HT in LMIC.

Placental pathology is necessary to understand common pregnancy complications and achieve an improved taxonomy of obstetrical disease

The importance of a fully functioning placenta for a good pregnancy outcome is unquestioned. Loss of function can lead to pregnancy complications and is often detected by a thorough placental pathologic examination. Placental pathology has advanced the science and practice of obstetrics and neonatal-perinatal medicine by classifying diseases according to underlying biology and specific patterns of injury. Many past obstacles have limited the incorporation of placental findings into both clinical studies and day-to-day practice. Limitations have included variability in the nomenclature used to describe placental lesions, a shortage of perinatal pathologists fully competent to analyze placental specimens, and a troubling lack of understanding of placental diagnoses by clinicians. However, the potential use of placental pathology for phenotypic classification, improved understanding of the biology of adverse pregnancy outcomes, the development of treatment and prevention, and patient counseling has never been greater. This review, written partly in response to a recent critique published in a major obstetrics-gynecology journal, reexamines the role of placental pathology by reviewing current concepts of biology; explaining the most recent terminology; emphasizing the usefulness of specific diagnoses for obstetrician-gynecologists, neonatologists, and patients; previewing upcoming changes in recommendations for placental submission; and suggesting future improvements. These improvements should include further consideration of overall healthcare costs, cost-effectiveness, the clinical value added of placental assessment, improvements in placental pathology education and practice, and leveraging of placental pathology to identify new biomarkers of disease and evaluate novel therapies tailored to specific clinicopathologic phenotypes of both women and infants.

Defining longer term outcomes in an ovine model of moderate perinatal hypoxia-ischemia

Hypoxic-ischemic encephalopathy (HIE) is the leading cause of neonatal morbidity and mortality worldwide. Approximately 1 million infants born with HIE each year survive with cerebral palsy (CP) and/or serious cognitive disabilities. While infants born with mild and severe HIE frequently result in predictable outcomes, infants born with moderate HIE exhibit variable outcomes that are highly unpredictable. Here, we describe an umbilical cord occlusion (UCO) model of moderate HIE with a 6-day follow-up. Near term lambs (n=27) are resuscitated after the induction of 5 minutes of asystole. Following recovery, lambs are assessed to define neurodevelopmental outcomes. At the end of this period, lambs are euthanized, and brains harvested for histological analysis. Compared with prior models that typically follow lambs for 3 days, the observation of neurobehavioral outcomes for 6 days enables identification of animals that recover significant neurological function. Approximately 35 % of lambs exhibited severe motor deficits throughout the entirety of the 6-day course and, in the most severely affected lambs, developed spastic diparesis similar to that observed in infants who survive severe neonatal HIE (severe, UCOs). Importantly, and similar to outcomes in human neonates, while initially developing significant acidosis and encephalopathy, the remainder of the lambs in this model recovered normal motor activity and exhibited normal neurodevelopmental outcomes by 6 days of life (improved, UCOi). The UCOs group exhibited gliosis and inflammation in both white and gray matter, oligodendrocyte loss, and neuronal loss and cellular death in the hippocampus and cingulate cortex. While the UCOi group exhibited more cellular death and gliosis in the parasagittal cortex and demonstrated more preserved white matter markers, along with reduced markers of inflammation and lower cellular death and neuronal loss in Ca3 of the hippocampus compared with UCOs lambs. Our large animal model of moderate HIE with prolonged follow-up will help further define pathophysiologic drivers of brain injury while enabling identification of predictive biomarkers that correlate with disease outcomes and ultimately help support development of therapeutic approaches to this challenging clinical scenario.

Outcomes of Very Preterm Infants Conceived with Assisted Reproductive Technologies

OBJECTIVE

To compare mortality and early respiratory outcomes of very preterm infants conceived via assisted reproductive technology (ART) vs spontaneously.

STUDY DESIGN

We identified inborn infants (July 2014-July 2019) with gestational age <32 weeks (n = 439); 54 cases were ART conceived. Spontaneously conceived controls (n = 103) were matched by multiple gestation status and gestational age. Primary outcome was 1-year mortality. Secondary outcomes were receipt of respiratory support and supplemental oxygen at 7 and 28 days and 36 weeks of postmenstrual age. We evaluated the association between conception method and outcomes by logistic regression, with adjustment for sociodemographic status.

RESULTS

Women who conceived via ART had increased rates of prepregnancy and gestational diabetes, and no differences in rates of hypertensive disorders. Infant 1-year mortality was not different by mode of conception (ART 11.8% vs spontaneous 7.1%, P = .49). Infants conceived by ART were less likely to receive respiratory support or supplemental oxygen at all time points, but this relationship only reached significance for receipt of oxygen at 28 days (ART 20.8% vs spontaneous 39.0%, P = .03); this remained true after adjustment for race/ethnicity and socioeconomic index.

CONCLUSIONS

When controlling for gestational age and multiple gestation status, very preterm infants conceived following ART had similar outcomes as those conceived spontaneously.

Monitoring deep-tissue oxygenation with a millimeter-scale ultrasonic implant

Vascular complications following solid organ transplantation may lead to graft ischemia, dysfunction or loss. Imaging approaches can provide intermittent assessments of graft perfusion, but require highly skilled practitioners and do not directly assess graft oxygenation. Existing systems for monitoring tissue oxygenation are limited by the need for wired connections, the inability to provide real-time data or operation restricted to surface tissues. Here, we present a minimally invasive system to monitor deep-tissue O₂ that reports continuous real-time data from centimeter-scale depths in sheep and up to a 10-cm depth in ex vivo porcine tissue. The system is composed of a millimeter-sized, wireless, ultrasound-powered implantable luminescence O₂ sensor and an external transceiver for bidirectional data transfer, enabling deep-tissue oxygenation monitoring for surgical or critical care indications.

Effect of culture conditions and method of conception on mouse live birth rate

OBJECTIVE

To understand in a mouse model whether there are differences in the decidua and live birth rate after transfer of blastocysts generated by in vitro fertilization (IVF) or by superovulation with spontaneous mating into unstimulated recipients.

DESIGN

Animal experiment.

SETTING

University-affiliated tertiary hospital.

ANIMAL(S)

Mice.

INTERVENTION(S)

IVF embryos were generated and cultured in either Whitten medium (WM, suboptimal conditions) and 20% O₂ or KSOM medium with amino acids (KAA, optimal conditions) and 5% O₂. The control blastocysts from superovulated mice were flushed out of the uterus 3.5 days (E3.5) after mating (FB group). The resulting blastocysts were transferred to nonsuperovulated CF1 recipients mated to vasectomized males. To understand whether anomalies of decidua were present, the expression of genes involved in decidual development and inflammation was analyzed at E7.5 and E18.5. Similarly, immunostaining was used to evaluate whether the pathways involved in activation of mTORC1 (p-S6) and Cox2 signaling (Cox 2 staining) were altered.

MAIN OUTCOME MEASURE(S)

Live birth rate, gene expression, and immunostaining of decidua.

RESULT(S)

Implantation rates at E7.5 were similar, but in vivo embryos (FB groups) were predicted to result in live births 3.3 times higher (2.2-5.1) and 6.6 times higher (4.7-9.3) compared with optimal and suboptimal cultures, respectively. Expression of genes involved in decidual development and inflammation or localization and intensity of staining for p-S6 (mTOR pathway), or inflammation (Cox 2 pathway) were not different among the groups.

CONCLUSION(S)

The predicted live birth rate was decreased in mouse embryos generated by IVF compared with embryos generated by mating, whereas the implantation rate was not different. Suboptimal culture conditions resulted in lower birth rate. We did not find evidence of abnormalities in decidualization that could explain these findings. These data indicate that blastocysts cultured in stressful conditions are less competent, suggesting that decreasing the number of embryonic manipulations may result in higher live birth rates.

Sex-specific epigenetic profile of inner cell mass of mice conceived in vivo or by IVF

The preimplantation stage of development is exquisitely sensitive to environmental stresses, and changes occurring during this developmental phase may have long-term health effects. Animal studies indicate that IVF offspring display metabolic alterations, including hypertension, glucose intolerance and cardiac hypertrophy, often in a sexual dimorphic fashion. The detailed nature of epigenetic changes following in-vitro culture is, however, unknown. This study was performed to evaluate the epigenetic (using whole-genome bisulfite sequencing (WGBS) and assay for transposase-accessible chromatin using sequencing (ATAC-seq)) and transcriptomic changes (using RNA-seq) occurring in the inner cell mass (ICM) of male or female mouse embryos generated in vivo or by IVF. We found that the ICM of IVF embryos, compared to the in-vivo ICM, differed in 3% of differentially methylated regions (DMRs), of which 0.1% were located on CpG islands. ATAC-seq revealed that 293 regions were more accessible and 101 were less accessible in IVF embryos, while RNA-seq revealed that 21 genes were differentially regulated in IVF embryos. Functional enrichment analysis revealed that stress signalling (STAT and NF-kB signalling), developmental processes and cardiac hypertrophy signalling showed consistent changes in WGBS and ATAC-seq platforms. In contrast, male and female embryos showed minimal changes. Male ICM had an increased number of significantly hyper-methylated DMRs, while only 27 regions showed different chromatin accessibility and only one gene was differentially expressed. In summary, this study provides the first comprehensive analysis of DNA methylation, chromatin accessibility and RNA expression changes induced by IVF in male and female ICMs. This dataset can be of value to all researchers interested in the developmental origin of health and disease (DOHaD) hypothesis and might lead to a better understanding of how early embryonic manipulation may affect adult health.

Complex interplay between autophagy and oxidative stress in the development of pulmonary disease

The autophagic pathway involves the encapsulation of substrates in double-membraned vesicles, which are subsequently delivered to the lysosome for enzymatic degradation and recycling of metabolic precursors. Autophagy is a major cellular defense against oxidative stress, or related conditions that cause accumulation of damaged proteins or organelles. Selective forms of autophagy can maintain organelle populations or remove aggregated proteins. Dysregulation of redox homeostasis under pathological conditions results in excessive generation of reactive oxygen species (ROS), leading to oxidative stress and the associated oxidative damage of cellular components. Accumulating evidence indicates that autophagy is necessary to maintain redox homeostasis. ROS activates autophagy, which facilitates cellular adaptation and diminishes oxidative damage by degrading and recycling intracellular damaged macromolecules and dysfunctional organelles. The cellular responses triggered by oxidative stress include the altered regulation of signaling pathways that culminate in the regulation of autophagy. Current research suggests a central role for autophagy as a mammalian oxidative stress response and its interrelationship to other stress defense systems. Altered autophagy phenotypes have been observed in lung diseases such as chronic obstructive lung disease, acute lung injury, cystic fibrosis, idiopathic pulmonary fibrosis, and pulmonary arterial hypertension, and asthma. Understanding the mechanisms by which ROS regulate autophagy will provide novel therapeutic targets for lung diseases. This review highlights our current understanding on the interplay between ROS and autophagy in the development of pulmonary disease.

Defining the ATPome reveals cross-optimization of metabolic pathways

Disrupted energy metabolism drives cell dysfunction and disease, but approaches to increase or preserve ATP are lacking. To generate a comprehensive metabolic map of genes and pathways that regulate cellular ATP-the ATPome-we conducted a genome-wide CRISPR interference/activation screen integrated with an ATP biosensor. We show that ATP level is modulated by distinct mechanisms that promote energy production or inhibit consumption. In our system HK2 is the greatest ATP consumer, indicating energy failure may not be a general deficiency in producing ATP, but rather failure to recoup the ATP cost of glycolysis and diversion of glucose metabolites to the pentose phosphate pathway. We identify systems-level reciprocal inhibition between the HIF1 pathway and mitochondria; glycolysis-promoting enzymes inhibit respiration even when there is no glycolytic ATP production, and vice versa. Consequently, suppressing alternative metabolism modes paradoxically increases energy levels under substrate restriction. This work reveals mechanisms of metabolic control, and identifies therapeutic targets to correct energy failure.

Human placental trophoblast progenitor cells (hTPCs) promote angiogenesis and neurogenesis after focal cerebral ischemia in rats

INTRODUCTION

Reduction of blood flow below a threshold value in brain regions locally or globally is called cerebral ischemia and proper treatment requires either the restoration of normal blood flow and/or the administration of neuroprotective therapies. Human trophoblast progenitor cells (hTPCs) give rise to the placenta and are responsible for the invasion and vascular remodeling of the maternal vessels within the uterus. Here, we tested whether hTPCs promoted to differentiate along neural lineages may exhibit therapeutic properties in the setting of cerebral ischemia in vivo.

MATERIALS AND METHODS

Cerebral ischemia was generated in rats via middle cerebral artery occlusion and, after 24 h, hTPCs were injected systemically via tail vein. Animals were sacrified at Day 3 or 11.

RESULTS

TTC staining indicated that infarct volumes were smaller in hTPC treated animals. Visible myelin recovery was observed in the hTPC injected group with Luxol Fast Blue staining. On Day 11 after hTPC transplantation, DLX5 and VEGF expression, as well as 2 and 10 d after hTPC transplantation, NKX2.2 were significantly increased; while LHX6, Olig1, PDGFRα, VEGFR1 and VEGFR2 showed trends toward improved expression in brain tissue via immunoblot analysis. Neuron-like differentiated cells were positive for both NeuN and Cresyl Violet staining.

CONCLUSION

Here, we demonstrate for the first time that hTPCs enhance the expression of angiogenic and neurogenic factors in rat brain after stroke. Transplantation of hTPCs could form the basis of novel therapeutic approaches for the treatment of stroke in the clinical setting.

Mechanical forces alter endothelin-1 signaling: comparative ovine models of congenital heart disease

The risk and progression of pulmonary vascular disease in patients with congenital heart disease is dependent on the hemodynamics associated with different lesions. However, the underlying mechanisms are not understood. Endothelin-1 is a potent vasoconstrictor that plays a key role in the pathology of pulmonary vascular disease. We utilized two ovine models of congenital heart disease: (1) fetal aortopulmonary graft placement (shunt), resulting in increased flow and pressure; and (2) fetal ligation of the left pulmonary artery resulting in increased flow and normal pressure to the right lung, to investigate the hypothesis that high pressure and flow, but not flow alone, upregulates endothelin-1 signaling. Lung tissue and pulmonary arterial endothelial cells were harvested from control, shunt, and the right lung of left pulmonary artery lambs at 3–7 weeks of age. We found that lung preproendothelin-1 mRNA and protein expression were increased in shunt lambs compared to controls. Preproendothelin-1 mRNA expression was modestly increased, and protein was unchanged in left pulmonary artery lambs. These changes resulted in increased lung endothelin-1 levels in shunt lambs, while left pulmonary artery levels were similar to controls. Pulmonary arterial endothelial cells exposed to increased shear stress decreased endothelin-1 levels by five-fold, while cyclic stretch increased levels by 1.5-fold. These data suggest that pressure or an additive effect of pressure and flow, rather than increased flow alone, is the principal driver of increased endothelin signaling in congenital heart disease. Defining the molecular drivers of the pathobiology of pulmonary vascular disease due to differing mechanical forces will allow for a more targeted therapeutic approach.

Ovine Models of Congenital Heart Disease and the Consequences of Hemodynamic Alterations for Pulmonary Artery Remodeling

The natural history of pulmonary vascular disease associated with congenital heart disease (CHD) depends on associated hemodynamics. Patients exposed to increased pulmonary blood flow (PBF) and pulmonary arterial pressure (PAP) develop pulmonary vascular disease more commonly than patients exposed to increased PBF alone. To investigate the effects of these differing mechanical forces on physiologic and molecular responses, we developed two models of CHD using fetal surgical techniques: 1) left pulmonary artery (LPA) ligation primarily resulting in increased PBF and 2) aortopulmonary shunt placement resulting in increased PBF and PAP. Hemodynamic, histologic, and molecular studies were performed on control, LPA, and shunt lambs as well as pulmonary artery endothelial cells (PAECs) derived from each. Physiologically, LPA, and to a greater extent shunt, lambs demonstrated an exaggerated increase in PAP in response to vasoconstricting stimuli compared with controls. These physiologic findings correlated with a pathologic increase in medial thickening in pulmonary arteries in shunt lambs but not in control or LPA lambs. Furthermore, in the setting of acutely increased afterload, the right ventricle of control and LPA but not shunt lambs demonstrates ventricular-vascular uncoupling and adverse ventricular-ventricular interactions. RNA sequencing revealed excellent separation between groups via both principal components analysis and unsupervised hierarchical clustering. In addition, we found hyperproliferation of PAECs from LPA lambs, and to a greater extent shunt lambs, with associated increased angiogenesis and decreased apoptosis in PAECs derived from shunt lambs. A further understanding of mechanical force-specific drivers of pulmonary artery pathology will enable development of precision therapeutics for pulmonary hypertension associated with CHD.

Outcomes of pulmonary vascular disease in infants conceived with non-IVF fertility treatment and assisted reproductive technologies at 1 year of age

BACKGROUND

Assisted reproductive technologies (ARTs) have been associated with the development of endothelial dysfunction.

OBJECTIVE

To determine potential differences in outcomes associated with pulmonary vascular disease in infants born to mothers receiving any infertility treatment including ART and non-IVF fertility treatments (NIFTs).

DESIGN/METHODS

The sample was derived from an administrative database containing detailed information on infant and maternal characteristics for live-born infants in California (2007-2012) with gestational age (GA) 22 to 44 weeks. Cases were defined as infants with ICD-9 code for pulmonary vascular disease (PVD) and records for ART/NIFT. Controls were randomly selected at a 1:4 ratio. The primary outcome was 1-year mortality. Crude and adjusted odds ratio (OR) with 95% confidence interval (CI) were calculated.

RESULTS

We identified 159 cases and 636 controls. Mothers that utilized ART/NIFT were older, to be of the Caucasian race, to have pre-eclampsia, private insurance, and education >12 years (P < .001). Cases compared to controls were more premature, had lower birth weights, and were more often the product of a multiple gestation pregnancy (P < .001). Cases had a higher 1-year mortality (18.2% vs 9.1%; OR: 2.2; 95% CI: 1.4, 3.6), more severe PVD (86.2% vs 72.3%; OR: 2.4; 95% CI: 1.5, 3.9), and a longer hospital stay (66.7 ± 73.0 vs 32.5 ± 47.2 days; P < .001) than controls. However, when adjusting for GA these differences become statistically insignificant.

CONCLUSION

Children born following ART/NIFT with PVD had increased mortality compared to infants with PVD but without ART/NIFT. The primary driver of this relationship is prematurity.

Biomechanical Forces and Oxidative Stress: Implications for Pulmonary Vascular Disease

Significance: Oxidative stress in the cell is characterized by excessive generation of reactive oxygen species (ROS). Superoxide (O₂^-) and hydrogen peroxide (H₂O₂) are the main ROS involved in the regulation of cellular metabolism. As our fundamental understanding of the underlying causes of lung disease has increased it has become evident that oxidative stress plays a critical role. Recent Advances: A number of cells in the lung both produce, and respond to, ROS. These include vascular endothelial and smooth muscle cells, fibroblasts, and epithelial cells as well as the cells involved in the inflammatory response, including macrophages, neutrophils, eosinophils. The redox system is involved in multiple aspects of cell metabolism and cell homeostasis. Critical Issues: Dysregulation of the cellular redox system has consequential effects on cell signaling pathways that are intimately involved in disease progression. The lung is exposed to biomechanical forces (fluid shear stress, cyclic stretch, and pressure) due to the passage of blood through the pulmonary vessels and the distension of the lungs during the breathing cycle. Cells within the lung respond to these forces by activating signal transduction pathways that alter their redox state with both physiologic and pathologic consequences. Future Directions: Here, we will discuss the intimate relationship between biomechanical forces and redox signaling and its role in the development of pulmonary disease. An understanding of the molecular mechanisms induced by biomechanical forces in the pulmonary vasculature is necessary for the development of new therapeutic strategies.

Pulmonary Endothelial Mechanical Sensing and Signaling, a Story of Focal Adhesions and Integrins in Ventilator Induced Lung Injury

Patients with critical illness such as acute lung injury often undergo mechanical ventilation in the intensive care unit. Though lifesaving in many instances, mechanical ventilation often results in ventilator induced lung injury (VILI), characterized by overdistension of lung tissue leading to release of edemagenic agents, which further damage the lung and contribute to the mortality and progression of pulmonary inflammation. The endothelium is particularly sensitive, as VILI associated mechanical stress results in endothelial cytoskeletal rearrangement, stress fiber formation, and integrity loss. At the heart of these changes are integrin tethered focal adhesions (FAs) which participate in mechanosensing, structure, and signaling. Here, we present the known roles of FA proteins including c-Src, talin, FAK, paxillin, vinculin, and integrins in the sensing and response to cyclic stretch and VILI associated stress. Attention is given to how stretch is propagated from the extracellular matrix through integrins to talin and other FA proteins, as well as signaling cascades that include FA proteins, leading to stress fiber formation and other cellular responses. This unifying picture of FAs aids our understanding in an effort to prevent and treat VILI.

The Gag protein PEG10 binds to RNA and regulates trophoblast stem cell lineage specification

Peg10 (paternally expressed gene 10) is an imprinted gene that is essential for placental development. It is thought to derive from a Ty3-gyspy LTR (long terminal repeat) retrotransposon and retains Gag and Pol-like domains. Here we show that the Gag domain of PEG10 can promote vesicle budding similar to the HIV p24 Gag protein. Expressed in a subset of mouse endocrine organs in addition to the placenta, PEG10 was identified as a substrate of the deubiquitinating enzyme USP9X. Consistent with PEG10 having a critical role in placental development, PEG10-deficient trophoblast stem cells (TSCs) exhibited impaired differentiation into placental lineages. PEG10 expressed in wild-type, differentiating TSCs was bound to many cellular RNAs including Hbegf (Heparin-binding EGF-like growth factor), which is known to play an important role in placentation. Expression of Hbegf was reduced in PEG10-deficient TSCs suggesting that PEG10 might bind to and stabilize RNAs that are critical for normal placental development.

Murine trophoblast-derived and pregnancy-associated exosome-enriched extracellular vesicle microRNAs: Implications for placenta driven effects on maternal physiology

The role of extracellular vesicles (EVs), specifically exosomes, in intercellular communication likely plays a key role in placental orchestration of pregnancy and maternal immune sensing of the fetus. While murine models are powerful tools to study pregnancy and maternal-fetal immune interactions, in contrast to human placental exosomes, the content of murine placental and pregnancy exosomes remains largely understudied. Using a recently developed in vitro culture technique, murine trophoblast stem cells derived from B6 mice were differentiated into syncytial-like cells. EVs from the conditioned media, as well as from pregnant and non-pregnant sera, were enriched for exosomes. The RNA composition of these murine trophoblast-derived and pregnancy-associated exosome-enriched-EVs (ExoE-EVs) was determined using RNA-sequencing analysis and expression levels confirmed by qRT-PCR. Differentially abundant miRNAs were detected in syncytial differentiated ExoE-EVs, particularly from the X chromosome cluster (mmu-miR-322-3p, mmu-miR-322-5p, mmu-miR-503-5p, mmu-miR-542-3p, and mmu-miR-450a-5p). These were confirmed to be increased in pregnant mouse sera ExoE-EVs by qRT-PCR analysis. Interestingly, fifteen miRNAs were only present within the pregnancy-derived ExoE-EVs compared to non-pregnant controls. Mmu-miR-292-3p and mmu-miR-183-5p were noted to be some of the most abundant miRNAs in syncytial ExoE-EVs and were also present at higher levels in pregnant versus non-pregnant sera ExoE-EVs. The bioinformatics tool, MultiMir, was employed to query publicly available databases of predicted miRNA-target interactions. This analysis reveals that the X-chromosome miRNAs are predicted to target ubiquitin-mediated proteolysis and intracellular signaling pathways. Knowing the cargo of placental and pregnancy-specific ExoE-EVs as well as the predicted biological targets informs studies using murine models to examine not only maternal-fetal immune interactions but also the physiologic consequences of placental-maternal communication.

Preservation of myocardial contractility during acute hypoxia with OMX-CV, a novel oxygen delivery biotherapeutic

The heart exhibits the highest basal oxygen (O₂) consumption per tissue mass of any organ in the body and is uniquely dependent on aerobic metabolism to sustain contractile function. During acute hypoxic states, the body responds with a compensatory increase in cardiac output that further increases myocardial O₂ demand, predisposing the heart to ischemic stress and myocardial dysfunction. Here, we test the utility of a novel engineered protein derived from the heme-based nitric oxide (NO)/oxygen (H-NOX) family of bacterial proteins as an O₂ delivery biotherapeutic (Omniox-cardiovascular [OMX-CV]) for the hypoxic myocardium. Because of their unique binding characteristics, H-NOX–based variants effectively deliver O₂ to hypoxic tissues, but not those at physiologic O₂ tension. Additionally, H-NOX–based variants exhibit tunable binding that is specific for O₂ with subphysiologic reactivity towards NO, circumventing a significant toxicity exhibited by hemoglobin (Hb)-based O₂ carriers (HBOCs). Juvenile lambs were sedated, mechanically ventilated, and instrumented to measure cardiovascular parameters. Biventricular admittance catheters were inserted to perform pressure-volume (PV) analyses. Systemic hypoxia was induced by ventilation with 10% O₂. Following 15 minutes of hypoxia, the lambs were treated with OMX-CV (200 mg/kg IV) or vehicle. Acute hypoxia induced significant increases in heart rate (HR), pulmonary blood flow (PBF), and pulmonary vascular resistance (PVR) (p < 0.05). At 1 hour, vehicle-treated lambs exhibited severe hypoxia and a significant decrease in biventricular contractile function. However, in OMX-CV–treated animals, myocardial oxygenation was improved without negatively impacting systemic or PVR, and both right ventricle (RV) and left ventricle (LV) contractile function were maintained at pre-hypoxic baseline levels. These data suggest that OMX-CV is a promising and safe O₂ delivery biotherapeutic for the preservation of myocardial contractility in the setting of acute hypoxia.

While hemoglobin is the primary oxygen delivery molecule used to maintain tissue oxygenation in metazoans, many organisms have other heme-containing proteins that can bind oxygen and other diatomic gases. Here, we tested whether a member of the H-NOX family of heme-containing proteins found in the thermostable bacterium Thermoanaerobacter tengcongensis can be engineered to deliver oxygen to severely hypoxic tissues in large mammals. This class of molecules has the advantage of high oxygen affinity and minimal nitric oxide reactivity. We demonstrate that these molecules can effectively deliver oxygen to a lamb heart with induced severe hypoxia, without overexposing the animal to oxygen or triggering systemic vascular reactivity. These molecules thus represent a novel class of oxygen delivery biotherapeutics to specifically target hypoxic tissue beds without the toxicity concerns of hemoglobin-based oxygen carriers. As tissue hypoxia is a central feature of many disease processes, this therapeutic approach may have broad clinical applicability.

KLF2-mediated disruption of PPAR-γ signaling in lymphatic endothelial cells exposed to chronically increased pulmonary lymph flow

Lymphatic abnormalities associated with congenital heart disease are well described, yet the underlying mechanisms remain poorly understood. Using a clinically relevant ovine model of congenital heart disease with increased pulmonary blood flow, we have previously demonstrated that lymphatic endothelial cells (LECs) exposed in vivo to chronically increased pulmonary lymph flow accumulate ROS and have decreased bioavailable nitric oxide (NO). Peroxisome proliferator-activated receptor-γ (PPAR-γ), which abrogates production of cellular ROS by NADPH oxidase, is inhibited by Krüppel-like factor 2 (KLF2), a flow-induced transcription factor. We hypothesized that chronically increased pulmonary lymph flow induces a KLF2-mediated decrease in PPAR-γ and an accumulation of cellular ROS, contributing to decreased bioavailable NO in LECs. To better understand the mechanisms that transduce the abnormal mechanical forces associated with chronically increased pulmonary lymph flow, LECs were isolated from the efferent vessel of the caudal mediastinal lymph node of control ( n = 5) and shunt ( n = 5) lambs. KLF2 mRNA and protein were significantly increased in shunt compared with control LECs, and PPAR-γ mRNA and protein were significantly decreased. In control LECs exposed to shear forces in vitro, we found similar alterations to KLF2 and PPAR-γ expression. In shunt LECs, NADPH oxidase subunit expression was increased, and bioavailable NO was significantly lower. Transfection of shunt LECs with KLF2 siRNA normalized PPAR-γ, ROS, and bioavailable NO. Conversely, pharmacological inhibition of PPAR-γ in control LECs increased ROS equivalent to levels in shunt LECs at baseline. Taken together, these data suggest that one mechanism by which NO-mediated lymphatic function is disrupted after chronic exposure to increased pulmonary lymph flow is through altered KLF2-dependent PPAR-γ signaling, resulting in increased NADPH oxidase activity, accumulation of ROS, and decreased bioavailable NO. NEW & NOTEWORTHY Lymphatic endothelial cells, when exposed in vivo to chronically elevated pulmonary lymph flow in a model of congenital heart disease with increased pulmonary blood flow, demonstrate Krüppel-like factor 2-dependent disrupted peroxisome proliferator-activated receptor-γ signaling that results in the accumulation of reactive oxygen species and decreased bioavailable nitric oxide.

Sonic Hedgehog Agonist Protects Against Complex Neonatal Cerebellar Injury

The cerebellum undergoes rapid growth during the third trimester and is vulnerable to injury and deficient growth in infants born prematurely. Factors associated with preterm cerebellar hypoplasia include chronic lung disease and postnatal glucocorticoid administration. We modeled chronic hypoxemia and glucocorticoid administration in neonatal mice to study whole cerebellar and cell type-specific effects of dual exposure. Chronic neonatal hypoxia resulted in permanent cerebellar hypoplasia. This was compounded by administration of prednisolone as shown by greater volume loss and Purkinje cell death. In the setting of hypoxia and prednisolone, administration of a small molecule Smoothened-Hedgehog agonist (SAG) preserved cerebellar volume and protected against Purkinje cell death. Such protective effects were observed even when SAG was given as a one-time dose after dual insult. To model complex injury and determine cell type-specific roles for the hypoxia inducible factor (HIF) pathway, we performed conditional knockout of von Hippel Lindau (VHL) to hyperactivate HIF1α in cerebellar granule neuron precursors (CGNP) or Purkinje cells. Surprisingly, HIF activation in either cell type resulted in no cerebellar deficit. However, in mice administered prednisolone, HIF overactivation in CGNPs resulted in significant cerebellar hypoplasia, whereas HIF overactivation in Purkinje cells caused cell death. Together, these findings indicate that HIF primes both cell types for injury via glucocorticoids, and that hypoxia/HIF + postnatal glucocorticoid administration act on distinct cellular pathways to cause cerebellar injury. They further suggest that SAG is neuroprotective in the setting of complex neonatal cerebellar injury.

Common and specific transcriptional signatures in mouse embryos and adult tissues induced by in vitro procedures

Stressful environmental exposures incurred early in development can affect postnatal metabolic health and susceptibility to non-communicable diseases in adulthood, although the molecular mechanisms by which this occurs have yet to be elucidated. Here we use a mouse model to investigate how assorted in vitro exposures restricted exclusively to the preimplantation period affect transcription both acutely in embryos and long-term in subsequent offspring adult tissues, to determine if reliable transcriptional markers of in vitro stress are present at specific developmental time points and throughout development. Each in vitro fertilization or embryo culture environment led to a specific and unique blastocyst transcriptional profile, but we identified a common 18-gene and 9-pathway signature of preimplantation embryo manipulation that was present in all in vitro embryos irrespective of culture condition or method of fertilization. This fingerprint did not persist throughout development and there was no clear transcriptional cohesion between adult IVF offspring tissues or compared to their preceding embryos, indicating a tissue-specific impact of in vitro stress on gene expression. However, the transcriptional changes present in each IVF tissue were targeted by the same upstream transcriptional regulators, which provide insight as to how acute transcriptional responses to stressful environmental exposures might be preserved throughout development to influence adult gene expression.

Pulmonary artery smooth muscle cell hyperproliferation and metabolic shift triggered by pulmonary overcirculation

Vascular cell hyperproliferation and metabolic reprogramming contribute to the pathophysiology of pulmonary arterial hypertension (PAH). An important cause of PAH in children with congenital heart disease (CHD) is increased pulmonary blood flow (PBF). To better characterize this disease course we studied early changes in pulmonary artery smooth muscle cell (PASMC) proliferation and metabolism using a unique ovine model of pulmonary overcirculation. Consistent with PAH in adults, PASMCs derived from 4-wk-old lambs exposed to increased PBF (shunt) exhibited increased rates of proliferation. While shunt PASMCs also exhibited significant decreases in mitochondrial oxygen consumption, membrane potential, and tricarboxylic acid (TCA) cycle function, suggesting a switch to Warburg metabolism as observed in advanced PAH in adults, they unexpectedly demonstrated decreased glycolytic lactate production, likely due to enhanced flux through the pentose phosphate pathway (PPP). This may be a response to the marked increase in NADPH oxidase (Nox) activity and decreased NADPH/NADP+ ratios observed in shunt PASMCs. Consistent with these findings, pharmacological inhibition of Nox activity preferentially slowed the growth of shunt PASMCs in vitro. Our results therefore indicate that PASMC hyperproliferation is observed early in the setting of pulmonary overcirculation and is accompanied by a unique metabolic profile that is independent of HIF-1α, PDHK1, or increased glycolytic flux. Our results also suggest that Nox inhibition may help prevent pulmonary overcirculation-induced PAH in children born with CHD.

Disrupted NOS signaling in lymphatic endothelial cells exposed to chronically increased pulmonary lymph flow

Associated abnormalities of the lymphatic circulation are well described in congenital heart disease. However, their mechanisms remain poorly elucidated. Using a clinically relevant ovine model of a congenital cardiac defect with chronically increased pulmonary blood flow (shunt), we previously demonstrated that exposure to chronically elevated pulmonary lymph flow is associated with: 1) decreased bioavailable nitric oxide (NO) in pulmonary lymph; and 2) attenuated endothelium-dependent relaxation of thoracic duct rings, suggesting disrupted lymphatic endothelial NO signaling in shunt lambs. To further elucidate the mechanisms responsible for this altered NO signaling, primary lymphatic endothelial cells (LECs) were isolated from the efferent lymphatic of the caudal mediastinal node in 4-wk-old control and shunt lambs. We found that shunt LECs (n = 3) had decreased bioavailable NO and decreased endothelial nitric oxide synthase (eNOS) mRNA and protein expression compared with control LECs (n = 3). eNOS activity was also low in shunt LECs, but, interestingly, inducible nitric oxide synthase (iNOS) expression and activity were increased in shunt LECs, as were total cellular nitration, including eNOS-specific nitration, and accumulation of reactive oxygen species (ROS). Pharmacological inhibition of iNOS reduced ROS in shunt LECs to levels measured in control LECs. These data support the conclusion that NOS signaling is disrupted in the lymphatic endothelium of lambs exposed to chronically increased pulmonary blood and lymph flow and may contribute to decreased pulmonary lymphatic bioavailable NO.

Metabolic Changes Precede the Development of Pulmonary Hypertension in the Monocrotaline Exposed Rat Lung

There is increasing interest in the potential for metabolic profiling to evaluate the progression of pulmonary hypertension (PH). However, a detailed analysis of the metabolic changes in lungs at the early stage of PH, characterized by increased pulmonary artery pressure but prior to the development of right ventricle hypertrophy and failure, is lacking in a preclinical animal model of PH. Thus, we undertook a study using rats 14 days after exposure to monocrotaline (MCT), to determine whether we could identify early stage metabolic changes prior to the manifestation of developed PH. We observed changes in multiple pathways associated with the development of PH, including activated glycolysis, increased markers of proliferation, disruptions in carnitine homeostasis, increased inflammatory and fibrosis biomarkers, and a reduction in glutathione biosynthesis. Further, our global metabolic profile data compare favorably with prior work carried out in humans with PH. We conclude that despite the MCT-model not recapitulating all the structural changes associated with humans with advanced PH, including endothelial cell proliferation and the formation of plexiform lesions, it is very similar at a metabolic level. Thus, we suggest that despite its limitations it can still serve as a useful preclinical model for the study of PH.

Placenta: the forgotten organ

The placenta sits at the interface between the maternal and fetal vascular beds where it mediates nutrient and waste exchange to enable in utero existence. Placental cells (trophoblasts) accomplish this via invading and remodeling the uterine vasculature. Amazingly, despite being of fetal origin, trophoblasts do not trigger a significant maternal immune response. Additionally, they maintain a highly reliable hemostasis in this extremely vascular interface. Decades of research into how the placenta differentiates itself from embryonic tissues to accomplish these and other feats have revealed a previously unappreciated level of complexity with respect to the placenta's cellular composition. Additionally, novel insights with respect to roles played by the placenta in guiding fetal development and metabolism have sparked a renewed interest in understanding the interrelationship between fetal and placental well-being. Here, we present an overview of emerging research in placental biology that highlights these themes and the importance of the placenta to fetal and adult health.

Abstract 640: PASMC Hyperproliferation and Metabolic Shift in a Model of Pulmonary Overcirculation

BACKGROUND: Pulmonary arterial hypertension (PAH) is a complex disease that lacks adequate therapies. Recognition that endothelial and smooth muscle cell hyper-proliferation contribute to the pathophysiology has drawn parallels to cancer biology and highlighted shared alterations in growth signaling and metabolism. Similar to the Warburg Effect described in malignancies, smooth muscle and endothelial cells exhibit a phenotype of aerobic glycolysis in the setting of PAH.

Objective: We hypothesize that in an animal model of increased pulmonary blood flow and early pulmonary vascular disease, smooth muscle cells from the central pulmonary arteries will exhibit metabolic alterations similar to the Warburg Effect.

DESIGN/METHODS: Fetal lambs underwent surgical placement of an aortopulmonary shunt resulting in a postnatal increase in pulmonary blood flow. Smooth muscle cells (PASMCs) from the central PAs were isolated for analysis. Extracellular flux analysis was used to measure concurrent oxygen consumption and extracellular acidification. Targeted metabolites were measured using HPLC-mass spectrometry.

Results: PASMCs from the shunted animals exhibit faster growth and a shorter calculated doubling time (29.5 vs. 45.2 hours). PASMCs derived from shunted animals had a 55% decrease in oxygen consumption rate and a 59% decrease in extracellular acidification rate. This is accompanied by a relative decrease in the mitochondrial membrane potential in the shunt cells compared to controls. Metabolic analysis shows increases in the PPP metabolites erythritol, S7P and R5P/X5P, decreases in the glycolytic metabolites Fru1,6BP and PEP, decreased malate in the TCA cycle and accumulation of acetyl-CoA in shunted cells compared to controls.

Conclusions: PASMCs from lambs with pulmonary overcirculation and early PAH have a phenotype of hyper-proliferation and altered metabolism. The low rate of oxygen consumption and extracellular acidification suggest concurrent decreases of both mitochondrial respiration and glycolytic flux. Targeted metabolite analysis suggests increased glucose entry into the pentose phosphate shunt rather than glycolysis and relative depletion of TCA cycle intermediates may underlie these observed changes.

HIGD1A-mediated dormancy and tumor survival

Solid tumors contain regions of anoxia that are also glucose deprived. How cancer cells survive such extreme conditions remains unclear. Here, we discuss our recent findings that regulation of hypoxia inducible gene domain family member 1 A (HIGD1A) via epigenetic mechanisms during glucose starvation modulates oxygen consumption and reactive oxygen species production to enable tumor cell survival through the activation of dormancy mechanisms.

Embryonic stem cells derived from in vivo or in vitro-generated murine blastocysts display similar transcriptome and differentiation potential

The use of assisted reproductive technologies (ART) such as in vitro fertilization (IVF) has resulted in the birth of more than 5 million children. While children conceived by these technologies are generally healthy, there is conflicting evidence suggesting an increase in adult-onset complications like glucose intolerance and high blood pressure in IVF children. Animal models indicate similar potential risks. It remains unclear what molecular mechanisms may be operating during in vitro culture to predispose the embryo to these diseases. One of the limitations faced by investigators is the paucity of the material in the preimplantation embryo to test for molecular analysis. To address this problem, we generated mouse embryonic stem cells (mESC) from blastocysts conceived after natural mating (mESC_FB) or after IVF, using optimal (KSOM + 5% O₂; mESC_KAA) and suboptimal (Whitten’s Medium, + 20% O₂, mESC_WM) conditions. All three groups of embryos showed similar behavior during both derivation and differentiation into their respective mESC lines. Unsupervised hierarchical clustering of microarray data showed that blastocyst culture does not affect the transcriptome of derived mESCs. Transcriptomic changes previously observed in the inner cell mass (ICM) of embryos derived in the same conditions were not present in mESCs, regardless of method of conception or culture medium, suggesting that mESC do not fully maintain a memory of the events occurring prior to their derivation. We conclude that the fertilization method or culture media used to generate blastocysts does not affect differentiation potential, morphology and transcriptome of mESCs.

HIGD1A Regulates Oxygen Consumption, ROS Production, and AMPK Activity during Glucose Deprivation to Modulate Cell Survival and Tumor Growth

Hypoxia-inducible gene domain family member 1A (HIGD1A) is a survival factor induced by hypoxia-inducible factor 1 (HIF-1). HIF-1 regulates many responses to oxygen deprivation, but viable cells within hypoxic perinecrotic solid tumor regions frequently lack HIF-1α. HIGD1A is induced in these HIF-deficient extreme environments and interacts with the mitochondrial electron transport chain to repress oxygen consumption, enhance AMPK activity, and lower cellular ROS levels. Importantly, HIGD1A decreases tumor growth but promotes tumor cell survival in vivo. The human Higd1a gene is located on chromosome 3p22.1, where many tumor suppressor genes reside. Consistent with this, the Higd1a gene promoter is differentially methylated in human cancers, preventing its hypoxic induction. However, when hypoxic tumor cells are confronted with glucose deprivation, DNA methyltransferase activity is inhibited, enabling HIGD1A expression, metabolic adaptation, and possible dormancy induction. Our findings therefore reveal important new roles for this family of mitochondrial proteins in cancer biology.

Sexually dimorphic effect of in vitro fertilization (IVF) on adult mouse fat and liver metabolomes

The preimplantation embryo is particularly vulnerable to environmental perturbation, such that nutritional and in vitro stresses restricted exclusively to this stage may alter growth and affect long-term metabolic health. This is particularly relevant to the over 5 million children conceived by in vitro fertilization (IVF). We previously reported that even optimized IVF conditions reprogram mouse postnatal growth, fat deposition, and glucose homeostasis in a sexually dimorphic fashion. To more clearly interrogate the metabolic changes associated with IVF in adulthood, we used nontargeted mass spectrometry to globally profile adult IVF- and in vivo-conceived liver and gonadal adipose tissues. There was a sex- and tissue-specific effect of IVF on adult metabolite signatures indicative of metabolic reprogramming and oxidative stress and reflective of the observed phenotypes. Additionally, we observed a striking effect of IVF on adult sexual dimorphism. Male-female differences in metabolite concentration were exaggerated in hepatic IVF tissue and significantly reduced in IVF adipose tissue, with the majority of changes affecting amino acid and lipid metabolites. We also observed female-specific changes in markers of oxidative stress and adipogenesis, including reduced glutathione, cysteine glutathione disulfide, ophthalmate, urate, and corticosterone. In summary, embryo manipulation and early developmental experiences can affect adult patterns of sexual dimorphism and metabolic physiology.

LIMK1 regulates human trophoblast invasion/differentiation and is down-regulated in preeclampsia

Successful human pregnancy requires extensive invasion of maternal uterine tissues by the placenta. Invasive extravillous trophoblasts derived from cytotrophoblast progenitors remodel maternal arterioles to promote blood flow to the placenta. In the pregnancy complication preeclampsia, extravillous trophoblasts invasion and vessel remodeling are frequently impaired, likely contributing to fetal underperfusion and maternal hypertension. We recently demonstrated in mouse trophoblast stem cells that hypoxia-inducible factor-2 (HIF-2)-dependent Lim domain kinase 1 (LIMK1) expression regulates invasive trophoblast differentiation by modulating the trophoblast cytoskeleton. Interestingly, in humans, LIMK1 activity promotes tumor cell invasion by modulating actin and microtubule integrity, as well as by modulating matrix metalloprotease processing. Here, we tested whether HIF-2α and LIMK1 expression patterns suggested similar roles in the human placenta. We found that LIMK1 immunoreactivity mirrored HIF-2α in the human placenta in utero and that LIMK1 activity regulated human cytotrophoblast cytoskeletal integrity, matrix metallopeptidase-9 secretion, invasion, and differentiation in vitro. Importantly, we also found that LIMK1 levels are frequently diminished in the preeclampsia setting in vivo. Our results therefore validate the use of mouse trophoblast stem cells as a discovery platform for human placentation disorders and suggest that LIMK1 activity helps promote human placental development in utero.

Oligodendrocyte-encoded HIF function couples postnatal myelination and white matter angiogenesis

Myelin sheaths provide critical functional and trophic support for axons in white matter tracts of the brain. Oligodendrocyte precursor cells (OPCs) have extraordinary metabolic requirements during development as they differentiate to produce multiple myelin segments, implying that they must first secure adequate access to blood supply. However, mechanisms that coordinate myelination and angiogenesis are unclear. Here, we show that oxygen tension, mediated by OPC-encoded hypoxia-inducible factor (HIF) function, is an essential regulator of postnatal myelination. Constitutive HIF1/2α stabilization resulted in OPC maturation arrest through autocrine activation of canonical Wnt7a/7b. Surprisingly, such OPCs also show paracrine activity that induces excessive postnatal white matter angiogenesis in vivo and directly stimulates endothelial cell proliferation in vitro. Conversely, OPC-specific HIF1/2α loss of function leads to insufficient angiogenesis in corpus callosum and catastrophic axon loss. These findings indicate that OPC-intrinsic HIF signaling couples postnatal white matter angiogenesis, axon integrity, and the onset of myelination in mammalian forebrain.

Use of a mouse in vitro fertilization model to understand the developmental origins of health and disease hypothesis

The Developmental Origins of Health and Disease hypothesis holds that alterations to homeostasis during critical periods of development can predispose individuals to adult-onset chronic diseases such as diabetes and metabolic syndrome. It remains controversial whether preimplantation embryo manipulation, clinically used to treat patients with infertility, disturbs homeostasis and affects long-term growth and metabolism. To address this controversy, we have assessed the effects of in vitro fertilization (IVF) on postnatal physiology in mice. We demonstrate that IVF and embryo culture, even under conditions considered optimal for mouse embryo culture, alter postnatal growth trajectory, fat accumulation, and glucose metabolism in adult mice. Unbiased metabolic profiling in serum and microarray analysis of pancreatic islets and insulin sensitive tissues (liver, skeletal muscle, and adipose tissue) revealed broad changes in metabolic homeostasis, characterized by systemic oxidative stress and mitochondrial dysfunction. Adopting a candidate approach, we identify thioredoxin-interacting protein (TXNIP), a key molecule involved in integrating cellular nutritional and oxidative states with metabolic response, as a marker for preimplantation stress and demonstrate tissue-specific epigenetic and transcriptional TXNIP misregulation in selected adult tissues. Importantly, dysregulation of TXNIP expression is associated with enrichment for H4 acetylation at the Txnip promoter that persists from the blastocyst stage through adulthood in adipose tissue. Our data support the vulnerability of preimplantation embryos to environmental disturbance and demonstrate that conception by IVF can reprogram metabolic homeostasis through metabolic, transcriptional, and epigenetic mechanisms with lasting effects for adult growth and fitness. This study has wide clinical relevance and underscores the importance of continued follow-up of IVF-conceived offspring.

Placental syncytium forms a biophysical barrier against pathogen invasion

Fetal syncytiotrophoblasts form a unique fused multinuclear surface that is bathed in maternal blood, and constitutes the main interface between fetus and mother. Syncytiotrophoblasts are exposed to pathogens circulating in maternal blood, and appear to have unique resistance mechanisms against microbial invasion. These are due in part to the lack of intercellular junctions and their receptors, the Achilles heel of polarized mononuclear epithelia. However, the syncytium is immune to receptor-independent invasion as well, suggesting additional general defense mechanisms against infection. The difficulty of maintaining and manipulating primary human syncytiotrophoblasts in culture makes it challenging to investigate the cellular and molecular basis of host defenses in this unique tissue. Here we present a novel system to study placental pathogenesis using murine trophoblast stem cells (mTSC) that can be differentiated into syncytiotrophoblasts and recapitulate human placental syncytium. Consistent with previous results in primary human organ cultures, murine syncytiotrophoblasts were found to be resistant to infection with Listeria monocytogenes via direct invasion and cell-to-cell spread. Atomic force microscopy of murine syncytiotrophoblasts demonstrated that these cells have a greater elastic modulus than mononuclear trophoblasts. Disruption of the unusually dense actin structure--a diffuse meshwork of microfilaments--with Cytochalasin D led to a decrease in its elastic modulus by 25%. This correlated with a small but significant increase in invasion of L. monocytogenes into murine and human syncytium. These results suggest that the syncytial actin cytoskeleton may form a general barrier against pathogen entry in humans and mice. Moreover, murine TSCs are a genetically tractable model system for the investigation of specific pathways in syncytial host defenses.

Hypoxia and trophoblast differentiation: a key role for PPARγ

Tissue oxygen tension regulates differentiation of multiple types of stem cells. In the placenta, hypoxia has been associated with abnormal trophoblast differentiation and placental insufficiency syndromes of preeclampsia (PE) and intrauterine growth restriction (IUGR). Peroxisome proliferator-activated receptor-γ (PPARγ) is a ligand-activated transcription factor involved in many cellular processes, including differentiation. We have previously shown that PPARγ-null trophoblast stem (TS) cells show a defect in differentiation to labyrinthine trophoblast, instead differentiating preferentially to trophoblast giant cells (TGC). Since PPARγ is known to be regulated by hypoxia in adipose tissue, we hypothesized that there may be a link between oxygen tension, PPARγ expression, and trophoblast differentiation. We found that hypoxia reduced PPARγ expression by a mechanism independent of both hypoxia-inducible factor (HIF) and histone deacetylases (HDACs). In addition, PPARγ partially rescued hypoxia-induced inhibition of labyrinthine differentiation in wild-type TS cells but was not required for hypoxia-induced inhibition of TGC differentiation. Finally, we show that induction of labyrinthine trophoblast differentiation by HDAC inhibitor treatment is independent of both PPARγ and Gcm1. We propose a model with two pathways for labyrinthine trophoblast differentiation of TS cells, one of which is dependent on PPARγ and inhibited by hypoxia. Since hypoxia is associated with PE and IUGR, we propose that PPARγ may at least partially mediate hypoxia-induced placental insufficiency and as such may be a promising therapeutic target for these disorders.

The effect of hypoxia on facial shape variation and disease phenotypes in chicken embryos

Craniofacial anomalies can arise from both genetic and environmental factors, including prenatal hypoxia. Recent clinical evidence correlates hypoxia to craniofacial malformations. However, the mechanisms by which hypoxia mediates these defects are not yet understood. We examined the cellular mechanisms underlying malformations induced by hypoxia using a chicken (Gallus gallus) embryo model. Eggs were incubated in either hypoxic (7, 9, 11, 13, 15, 17 or 19% O2) or normoxic (21% O2) conditions. Embryos were photographed for morphological analysis at days 3-6. For analysis of skeletal development, 13-day embryos were cleared and stained with alcian blue and alizarin red for cartilage and bone, respectively. Quantitative analysis of facial shape variation was performed on images of embryos via geometric morphometrics. Early-stage embryos (day 2) were analyzed for apoptosis via whole-mount and section TUNEL staining and immunostaining for cleaved caspase-3, whereas later-stage embryos (days 4-6) were sectioned in paraffin for analysis of cell proliferation (BrdU), apoptosis (TUNEL) and metabolic stress (phospho-AMPK). Results demonstrate that survival is reduced in a dose-dependent manner. Hypoxic embryos displayed a spectrum of craniofacial anomalies, from mild asymmetry and eye defects to more severe frontonasal and cephalic anomalies. Skull bone development was delayed in hypoxic embryos, with some skeletal defects observed. Morphometric analysis showed facial shape variation relative to centroid size and age in hypoxic groups. Hypoxia disrupted cell proliferation and, in early-stage embryos, caused apoptosis of neural crest progenitor cells. Hypoxic embryos also displayed an increased metabolic stress response. These results indicate that hypoxia during early embryonic craniofacial development might induce cellular oxidative stress, leading to apoptosis of the neural crest progenitor cells that are crucial to normal craniofacial morphogenesis.

ECM-dependent HIF induction directs trophoblast stem cell fate via LIMK1-mediated cytoskeletal rearrangement

The Hypoxia-inducible Factor (HIF) family of transcriptional regulators coordinates the expression of dozens of genes in response to oxygen deprivation. Mammalian development occurs in a hypoxic environment and HIF-null mice therefore die in utero due to multiple embryonic and placental defects. Mouse embryonic stem cells do not differentiate into placental cells; therefore, trophoblast stem cells (TSCs) are used to study mouse placental development. Consistent with a requirement for HIF activity during placental development in utero, TSCs derived from HIF-null mice exhibit severe differentiation defects and fail to form trophoblast giant cells (TGCs) in vitro. Interestingly, differentiating TSCs induce HIF activity independent of oxygen tension via unclear mechanisms. Here, we show that altering the extracellular matrix (ECM) composition upon which TSCs are cultured changes their differentiation potential from TGCs to multinucleated syncytiotropholasts (SynTs) and blocks oxygen-independent HIF induction. We further find that modulation of Mitogen Activated Protein Kinase Kinase-1/2 (MAP2K1/2, MEK-1/2) signaling by ECM composition is responsible for this effect. In the absence of ECM-dependent cues, hypoxia-signaling pathways activate this MAPK cascade to drive HIF induction and redirect TSC fate along the TGC lineage. In addition, we show that integrity of the microtubule and actin cytoskeleton is critical for TGC fate determination. HIF-2α ensures TSC cytoskeletal integrity and promotes invasive TGC formation by interacting with c-MYC to induce non-canonical expression of Lim domain kinase 1-an enzyme that regulates microtubule and actin stability, as well as cell invasion. Thus, we find that HIF can integrate positional and metabolic cues from within the TSC niche to regulate placental development by modulating the cellular cytoskeleton via non-canonical gene expression.

Effect of substrate stiffness on early mouse embryo development

It is becoming increasingly clear that cells are remarkably sensitive to the biophysical cues of their microenvironment and that these cues play a significant role in influencing their behaviors. In this study, we investigated whether the early pre-implantation embryo is sensitive to mechanical cues, i.e. the elasticity of the culture environment. To test this, we have developed a new embryo culture system where the mechanical properties of the embryonic environment can be precisely defined. The contemporary standard environment for embryo culture is the polystyrene petri dish (PD), which has a stiffness (1 GPa) that is six orders of magnitude greater than the uterine epithelium (1 kPa). To approximate more closely the mechanical aspects of the in vivo uterine environment we used polydimethyl-siloxane (PDMS) or fabricated 3D type I collagen gels (1 kPa stiffness, Col-1k group). Mouse embryo development on alternate substrates was compared to that seen on the petri dish; percent development, hatching frequency, and cell number were observed. Our results indicated that embryos are sensitive to the mechanical environment on which they are cultured. Embryos cultured on Col-1k showed a significantly greater frequency of development to 2-cell (68 ± 15% vs. 59 ± 18%), blastocyst (64 ± 9.1% vs. 50 ± 18%) and hatching blastocyst stages (54 ± 25% vs. 21 ± 16%) and an increase in the number of trophectodermal cell (TE,65 ± 13 vs. 49 ± 12 cells) compared to control embryos cultured in PD (mean ± S.D.; p<.01). Embryos cultured on Col-1k and PD were transferred to recipient females and observed on embryonic day 12.5. Both groups had the same number of fetuses, however the placentas of the Col-1k fetuses were larger than controls, suggesting a continued effect of the preimplantation environment. In summary, characteristics of the preimplantation microenvironment affect pre- and post-implantation growth.

Impaired placental nutrient transport in mice generated by in vitro fertilization

More than 4.5 million children have been conceived by in vitro fertilization (IVF). Interestingly, singleton IVF offspring born at term have an increased incidence of low birth weight. The mechanism responsible for the lower birth weight is unknown, but alterations in placental function are possible. Hence, the goal of our study was to examine placental growth and function in mice generated in vivo or in vitro. To assess placental function, blastocysts were generated by IVF or produced by natural mating (control group); both IVF and control blastocysts were transferred to pseudopregnant recipients. Placental weights did not differ at embryonic d 15.5 (E15.5) but were increased at E18.5 in the IVF group (25.4%, P < 0.001) compared with control. Proliferation was increased in IVF placentae, whereas overall placental gross morphology and apoptosis were not affected. Both fetal weights (16.4% lower at E15.5 and 8.8% lower at E18.5, P < 0.05) and fetal to placental ratios were lower (P < 0.001) in the IVF compared with the control group at both time points, whereas birth weights did not differ. At E18.5, the mRNA for selected glucose, system A amino acid transporters, and imprinted genes were down-regulated in IVF placentae. GLUT3 protein level was decreased in the IVF group (P < 0.05). Importantly, intrajugular injections of (14)C-methyl-D-glucose or (14)C-MeAIB tracers (n = 6 litters per group) showed that placental transport of glucose and amino acids were 24.8% (not significant) and 58.1% (P < 0.05) lower in the IVF group. Fetal accumulation of glucose was not different, but amino acid accumulation was significantly (36 %) lower in IVF fetuses (P < 0.05). We conclude that IVF alters both fetal and placental growth and, importantly, decreases placental transport efficiency in mice conceived by IVF.

In vitro culture of mouse embryos reduces differential gene expression between inner cell mass and trophectoderm

Differences in gene expression and imprinting have been reported, comparing in vivo versus in vitro generated preimplantation embryos. Furthermore, mouse studies have shown that placenta development is altered following in vitro culture. However, the molecular mechanisms underlying these findings are unknown. We therefore isolated trophectoderm (TE) and inner cell mass (ICM) cells from in vivo and in vitro fertilization (IVF) embryos and evaluated their transcriptome using microarrays. We found that the transcriptomes of in vitro produced ICM and TE cells showed remarkably few differences compared to ICM and TE cells of in vivo generated embryos. In vitro fertilization embryos showed a reduced number of TE cells compared to in vivo embryos. In addition, TE of IVF embryos showed significant downregulation of solute transporter genes and of genes involved in placenta formation (Eomesodermin, Socs3) or implantation (Hbegf). In summary, IVF and embryo culture significantly affects the transcriptome of ICM and TE cells.

A role for Notch signaling in trophoblast endovascular invasion and in the pathogenesis of pre-eclampsia

Placental trophoblasts (TBs) invade and remodel uterine vessels with an arterial bias. This process, which involves vascular mimicry, re-routes maternal blood to the placenta, but fails in pre-eclampsia. We investigated Notch family members in both contexts, as they play important roles in arterial differentiation/function. Immunoanalyses of tissue sections showed step-wise modulation of Notch receptors/ligands during human TB invasion. Inhibition of Notch signaling reduced invasion of cultured human TBs and expression of the arterial marker EFNB2. In mouse placentas, Notch activity was highest in endovascular TBs. Conditional deletion of Notch2, the only receptor upregulated during mouse TB invasion, reduced arterial invasion, the size of maternal blood canals by 30-40% and placental perfusion by 23%. By E11.5, there was litter-wide lethality in proportion to the number of mutant offspring. In pre-eclampsia, expression of the Notch ligand JAG1 was absent in perivascular and endovascular TBs. We conclude that Notch signaling is crucial for TB vascular invasion.