Uteroplacental adenovirus vascular endothelial growth factor gene therapy increases fetal growth velocity in growth-restricted sheep pregnancies

Fetal therapies - (Stem cell transplantation; enzyme replacement therapy; in utero genetic therapies)

Advances in ultrasound and prenatal diagnosis are leading an expansion in the options for parents whose fetus is identified with a congenital disease. Obstetric diseases such as pre-eclampsia and fetal growth restriction may also be amenable to intervention to improve maternal and neonatal outcomes. Advanced Medicinal Therapeutic Products such as stem cell, gene, enzyme and protein therapies are most commonly being investigated as the trajectory of treatment for severe genetic diseases moves toward earlier intervention. Theoretical benefits include prevention of in utero damage, smaller treatment doses compared to postnatal intervention, use of fetal circulatory shunts and induction of immune tolerance. New systematic terminology can capture adverse maternal and fetal adverse events to improve safe trial conduct. First-in-human clinical trials are now beginning to generate results with a focus on safety first and efficacy second. If successful, these trials will transform the care of fetuses with severe early-onset congenital disease.

Placenta-targeted Treatment Strategies for Preeclampsia and Fetal Growth Restriction: An Opportunity and Major Challenge

The placenta plays a crucial role in maintaining normal pregnancy. The failure of spiral artery remodeling (SAR) is a key factor leading to placental ischemia and poor perfusion which is strongly associated with obstetric diseases, including preeclampsia (PE) and fetal growth restriction (FGR). Existing interventions for PE and FGR are limited and termination of pregnancy is inevitable when the maternal or fetus condition deteriorates. Considering the safety of the mother and fetus, treatments that may penetrate the placental barrier and harm the fetus are not accepted. Developing targeted treatment strategies for these conditions is urgent and necessary. With the proven efficacy of targeted therapy in treating conditions such as endometrial cancer and trophoblastic tumors, research on placental dysfunction continues to deepen. This article reviews the studies on placenta-targeted treatment and drug delivery strategies, summarizes the characteristics proposes corresponding improvement measures in targeted treatment, provides solutions for existing problems, and makes suggestions for future studies.

Maternal Uterine Artery Adenoviral Vascular Endothelial Growth Factor (Ad.VEGF-A165) Gene Therapy Normalises Fetal Brain Growth and Microglial Activation in Nutrient Restricted Pregnant Guinea Pigs

Fetal growth restriction (FGR) is associated with uteroplacental insufficiency, and neurodevelopmental and structural brain deficits in the infant. It is currently untreatable. We hypothesised that treating the maternal uterine artery with vascular endothelial growth factor adenoviral gene therapy (Ad.VEGF-A165) normalises offspring brain weight and prevents brain injury in a guinea pig model of FGR. Pregnant guinea pigs were fed a restricted diet before and after conception and received Ad.VEGF-A165 (1 × 1010 viral particles, n = 18) or vehicle (n = 18), delivered to the external surface of the uterine arteries, in mid-pregnancy. Pregnant, ad libitum-fed controls received vehicle only (n = 10). Offspring brain weight and histological indices of brain injury were assessed at term and 5-months postnatally. At term, maternal nutrient restriction reduced fetal brain weight and increased microglial ramification in all brain regions but did not alter indices of cell death, astrogliosis or myelination. Ad.VEGF-A165 increased brain weight and reduced microglial ramification in fetuses of nutrient restricted dams. In adult offspring, maternal nutrient restriction did not alter brain weight or markers of brain injury, whilst Ad.VEGF-A165 increased microglial ramification and astrogliosis in the hippocampus and thalamus, respectively. Ad.VEGF-A165 did not affect cell death or myelination in the fetal or offspring brain. Ad.VEGF-A165 normalises brain growth and markers of brain injury in guinea pig fetuses exposed to maternal nutrient restriction and may be a potential intervention to improve childhood neurodevelopmental outcomes in pregnancies complicated by FGR.

Placental Drug Delivery to Treat Pre-Eclampsia and Fetal Growth Restriction

Pre-eclampsia and fetal growth restriction (FGR) continue to cause unacceptably high levels of morbidity and mortality, despite significant pharmaceutical and technological advances in other disease areas. The recent pandemic has also impacted obstetric care, as COVID-19 infection increases the risk of poor pregnancy outcomes. This review explores the reasons why it lacks effective drug treatments for the placental dysfunction that underlies many common obstetric conditions and describes how nanomedicines and targeted drug delivery approaches may provide the solution to the current drug drought. The ever-increasing range of biocompatible nanoparticle formulations available is now making it possible to selectively deliver drugs to uterine and placental tissues and dramatically limit fetal drug transfer. Formulations that are refractory to placental uptake offer the possibility of retaining drugs within the maternal circulation, allowing pregnant individuals to take medicines previously considered too harmful to the developing baby. Liposomes, ionizable lipid nanoparticles, polymeric nanoparticles, and adenoviral vectors have all been used to create efficacious drug delivery systems for use in pregnancy, although each approach offers distinct advantages and limitations. It is imperative that recent advances continue to be built upon and that there is an overdue investment of intellectual and financial capital in this field.

Effect of low-molecular-weight heparin on placenta-mediated fetal growth restriction in a tertiary referral hospital: A 7-year retrospective cohort study

OBJECTIVE

To investigate the effect of low-molecular-weight heparin (LMWH) on placenta-mediated fetal growth restriction (FGR).

METHODS

A cohort of 570 pregnant women diagnosed with placenta-mediated FGR were enrolled from January 1, 2015 through to December 31, 2021. A birth database, including demographic data, antenatal complications, and detailed delivery and newborn data, was created to collect variables from the Hospital Information System (HIS) Database. The unique personal registration number, assigned to each patient on first registration with HIS in the West China Second University Hospital, was used to link these patients. LMWH use was defined as at least 1-week prescription from diagnosis of placenta-mediated FGR. Pregnant women received LMWH (Enoxaparin 4000 IU/day) by self-administered subcutaneous injection only when they agreed and signed informed consent. Primary outcome was intrauterine fetal death after 20 weeks of pregnancy. Secondary outcomes included preterm birth (PB), Apgar score less than 7 at 1 min, admission to neonatal intensive care unit (NICU), and birth weight. Logistic regression analysis was conducted to compute adjusted odds ratio (aOR) with 95% confidence intervals (CI) for outcomes.

RESULTS

After controlling for confounders, LMWH use was associated with a decreased risk of intrauterine fetal death (aOR 2.49, 95% CI 1.35-4.57, P = 0.003), PB before 37 weeks of pregnancy (aOR 3.35, 95% CI 2.14-5.23, P < 0.001), PB before 34 weeks of pregnancy (aOR 2.25, 95% CI 1.36-3.74, P = 0.002), Apgar score less than 7 at 1 min (aOR 2.25, 95% CI 1.36-3.74, P = 0.002), NICU admission (aOR 2.29, 95% CI 1.48-3.55, P < 0.001). Using LMWH increased the mean birth weight in PB before 32 weeks of pregnancy (mean ± standard deviation [SD] 1126.4 ± 520.0 g, P = 0.020), PB before 37 weeks of pregnancy (mean ± SD 1563.9 ± 502.7 g, P = 0.019), early-onset FGR (mean ± SD 2125.2 ± 665.7 g, P < 0.001), late-onset FGR (mean ± SD 2343.4 ± 507.9, P < 0.001), and non-severe FGR (mean ± SD 2231.1 ± 607.2 g, P < 0.001).

CONCLUSION

Use of LMWH can significantly improve the fetal and neonatal outcomes among pregnant women with placenta-mediated FGR, particularly reducing the risk of intrauterine fetal death.

Maternal-fetal cross-talk via the placenta: influence on offspring development and metabolism

Compelling epidemiological and animal experimental data demonstrate that cardiometabolic and neuropsychiatric diseases originate in a suboptimal intrauterine environment. Here, we review evidence suggesting that altered placental function may, at least in part, mediate the link between the maternal environment and changes in fetal growth and development. Emerging evidence indicates that the placenta controls the development and function of several fetal tissues through nutrient sensing, modulation of trophoblast nutrient transporters and by altering the number and cargo of released extracellular vesicles. In this Review, we discuss the development and functions of the maternal-placental-fetal interface (in humans and mice) and how cross-talk between these compartments may be a mechanism for in utero programming, focusing on mechanistic target of rapamycin (mTOR), adiponectin and O-GlcNac transferase (OGT) signaling. We also discuss how maternal diet and stress influences fetal development and metabolism and how fetal growth restriction can result in susceptibility to developing chronic disease later in life. Finally, we speculate how interventions targeting placental function may offer unprecedented opportunities to prevent cardiometabolic disease in future generations.

Extracellular vesicle-mediated targeting strategies for long-term health benefits in gestational diabetes

Extracellular vesicles (EVs) are critical mediators of cell communication, playing important roles in regulating molecular cross-talk between different metabolic tissues and influencing insulin sensitivity in both healthy and gestational diabetes mellitus (GDM) pregnancies. The ability of EVs to transfer molecular cargo between cells imbues them with potential as therapeutic agents. During pregnancy, the placenta assumes a vital role in metabolic regulation, with multiple mechanisms of placenta-mediated EV cross-talk serving as central components in GDM pathophysiology. This review focuses on the role of the placenta in the pathophysiology of GDM and explores the possibilities and prospects of targeting the placenta to address insulin resistance and placental dysfunction in GDM. Additionally, we propose the use of EVs as a novel method for targeted therapeutics in treating the dysfunctional placenta. The primary aim of this review is to comprehend the current status of EV targeting approaches and assess the potential application of these strategies in placental therapeutics, thereby delivering molecular cargo and improving maternal and fetal outcomes in GDM. We propose that EVs have the potential to revolutionize GDM management, offering hope for enhanced maternal-fetal health outcomes and more effective treatments.

Rational Design of Nanomedicine for Placental Disorders: Birthing a New Era in Women's Reproductive Health

The placenta is a transient organ that forms during pregnancy and acts as a biological barrier, mediating exchange between maternal and fetal circulation. Placental disorders, such as preeclampsia, fetal growth restriction, placenta accreta spectrum, and gestational trophoblastic disease, originate in dysfunctional placental development during pregnancy and can lead to severe complications for both the mother and fetus. Unfortunately, treatment options for these disorders are severely lacking. Challenges in designing therapeutics for use during pregnancy involve selectively delivering payloads to the placenta while protecting the fetus from potential toxic side effects. Nanomedicine holds great promise in overcoming these barriers; the versatile and modular nature of nanocarriers, including prolonged circulation times, intracellular delivery, and organ-specific targeting, can control how therapeutics interact with the placenta. In this review, nanomedicine strategies are discussed to treat and diagnose placental disorders with an emphasis on understanding the unique pathophysiology behind each of these diseases. Finally, prior study of the pathophysiologic mechanisms underlying these placental disorders has revealed novel disease targets. These targets are highlighted here to motivate the rational design of precision nanocarriers to improve therapeutic options for placental disorders.

Analysis of a maternal health medicines pipeline database 2000-2021: New candidates for the prevention and treatment of fetal growth restriction

OBJECTIVE

The Accelerating Innovation for Mothers project established a new database of candidate medicines under development between 2000 and 2021 for five pregnancy-related conditions, including fetal growth restriction. The objective was to assess medicines for fetal growth restriction and their potential for clinical use globally.

DESIGN

Landscape analysis.

SETTING

Global (focus on low- and middle-income countries, LMICs).

SAMPLE

Drugs, dietary supplements and biologics under investigation for prevention or treatment of fetal growth restriction.

METHODS

A research pipeline database of medicines was created through searching AdisInsight, PubMed and various grant and clinical trial databases. Analysis of clinical and preclinical candidates were descriptive.

MAIN OUTCOMES MEASURES

Fetal growth restriction candidates in clinical development were identified and ranked as high, medium or low potential based on prespecified criteria, including efficacy, safety and accessibility.

RESULTS

Of the 444 unique candidates in the database across all five pregnancy-related conditions, 63 were for fetal growth restriction. Of these, 31 were in clinical development (phases I, II or III) and 32 were in preclinical development. Three candidates, aspirin, l-arginine and vitamin D, were ranked as having high potential as preventive agents. There were no high-potential candidates for treating fetal growth restriction, although five candidates were ranked as having medium potential: allylestrenol, dalteparin, omega-3 fatty acids, tadalafil, and United Nations International Multiple Micronutrient Antenatal Preparation (UNIMMAP).

CONCLUSIONS

l-Arginine, aspirin and vitamin D are promising, high-potential preventative agents for fetal growth restriction. Based on the medicines pipeline, new pharmacological agents for fetal growth restriction are unlikely to emerge in the near future.

Prenatal interventions for fetal growth restriction in animal models: A systematic review

Fetal growth restriction (FGR) in human pregnancy is associated with perinatal mortality, short- and long-term morbidities. No prenatal therapy is currently established despite decades of research. We aimed to review interventions in animal models for prenatal FGR treatment, and to seek the next steps for an effective clinical therapy. We registered our protocol and searched MEDLINE, Embase, and The Cochrane Library with no language restrictions, in accordance with the PRISMA guideline. We included all studies that reported the effects of any prenatal intervention in animal models of induced FGR. From 3257 screened studies, 202 describing 237 interventions were included for the final synthesis. Mice and rats were the most used animals (79%) followed by sheep (16%). Antioxidants (23%), followed by vasodilators (18%), nutrients (14%), and immunomodulators (12%) were the most tested therapy. Two-thirds of studies only reported delivery or immediate neonatal outcomes. Adverse effects were rarely reported (11%). Most studies (73%), independent of the intervention, showed a benefit in fetal survival or birthweight. The risk of bias was high, mostly due to the lack of randomization, allocation concealment, and blinding. Future research should aim to describe both short- and long-term outcomes across various organ systems in well-characterized models. Further efforts must be made to reduce selection, performance, and detection bias.

Interventions for placental insufficiency and fetal growth restriction

Pregnancy complications adversely impact both mother and/or fetus throughout the lifespan. Fetal growth restriction (FGR) occurs when a fetus fails to reach their intrauterine potential for growth, it is the second highest leading cause of infant mortality, and leads to increased risk of developing non-communicable diseases in later life due 'fetal programming'. Abnormal placental development, growth and/or function underlies approximately 75% of FGR cases and there is currently no treatment save delivery, often prematurely. We previously demonstrated in a murine model of FGR that nanoparticle mediated, intra-placental human IGF-1 gene therapy maintains normal fetal growth. Multiple models of FGR currently exist reflecting the etiologies of human FGR and have been used by us and others to investigate the development of in utero therapeutics as discussed here. In addition to the in vivo models discussed herein, utilizing human models including in vitro (Choriocarcinoma cell lines and primary trophoblasts) and ex vivo (term villous fragments and placenta cotyledon perfusion) we have demonstrated robust nanoparticle uptake, transgene expression, nutrient transporter regulation without transfer to the fetus. For translational gene therapy application in the human placenta, there are multiple avenues that require investigation including syncytial uptake from the maternal circulation, transgene expression, functionality and longevity of treatment, impact of treatment on the mother and developing fetus. The potential impact of treating the placenta during gestation is high, wide-ranging across pregnancy complications, and may offer reduced risk of developing associated cardio-metabolic diseases in later life impacting at both an individual and societal level.

Gene Therapy for Malignant and Benign Gynaecological Disorders: A Systematic Review of an Emerging Success Story

Simple Summary

This review discusses all the major advances in gene therapy of gynaecological disorders, highlighting the novel and potentially therapeutic perspectives associated with such an approach. It specifically focuses on the gene therapy strategies against major gynaecological malignant disorders, such as ovarian, cervical, and endometrial cancer, as well as benign disorders, such as uterine leiomyomas, endometriosis, placental, and embryo implantation disorders. The above therapeutic strategies, which employ both viral and non-viral systems for mutation compensation, suicide gene therapy, oncolytic virotherapy, antiangiogenesis and immunopotentiation approaches, have yielded promising results over the last decade, setting the grounds for successful clinical trials.

Abstract

Despite the major advances in screening and therapeutic approaches, gynaecological malignancies still present as a leading cause of death among women of reproductive age. Cervical cancer, although largely preventable through vaccination and regular screening, remains the fourth most common and most lethal cancer type in women, while the available treatment schemes still pose a fertility threat. Ovarian cancer is associated with high morbidity rates, primarily due to lack of symptoms and high relapse rates following treatment, whereas endometrial cancer, although usually curable by surgery, it still represents a therapeutic problem. On the other hand, benign abnormalities, such as fibroids, endometriosis, placental, and embryo implantation disorders, although not life-threatening, significantly affect women’s life and fertility and have high socio-economic impacts. In the last decade, targeted gene therapy approaches toward both malignant and benign gynaecological abnormalities have led to promising results, setting the ground for successful clinical trials. The above therapeutic strategies employ both viral and non-viral systems for mutation compensation, suicide gene therapy, oncolytic virotherapy, antiangiogenesis and immunopotentiation. This review discusses all the major advances in gene therapy of gynaecological disorders and highlights the novel and potentially therapeutic perspectives associated with such an approach.

The importance of nutrition in pregnancy and lactation: lifelong consequences

Most women in the United States do not meet the recommendations for healthful nutrition and weight before and during pregnancy. Women and providers often ask what a healthy diet for a pregnant woman should look like. The message should be “eat better, not more.” This can be achieved by basing diet on a variety of nutrient-dense, whole foods, including fruits, vegetables, legumes, whole grains, healthy fats with omega-3 fatty acids that include nuts and seeds, and fish, in place of poorer quality highly processed foods. Such a diet embodies nutritional density and is less likely to be accompanied by excessive energy intake than the standard American diet consisting of increased intakes of processed foods, fatty red meat, and sweetened foods and beverages. Women who report “prudent” or “health-conscious” eating patterns before and/or during pregnancy may have fewer pregnancy complications and adverse child health outcomes. Comprehensive nutritional supplementation (multiple micronutrients plus balanced protein energy) among women with inadequate nutrition has been associated with improved birth outcomes, including decreased rates of low birthweight. A diet that severely restricts any macronutrient class should be avoided, specifically the ketogenic diet that lacks carbohydrates, the Paleo diet because of dairy restriction, and any diet characterized by excess saturated fats. User-friendly tools to facilitate a quick evaluation of dietary patterns with clear guidance on how to address dietary inadequacies and embedded support from trained healthcare providers are urgently needed.

Recent evidence has shown that although excessive gestational weight gain predicts adverse perinatal outcomes among women with normal weight, the degree of prepregnancy obesity predicts adverse perinatal outcomes to a greater degree than gestational weight gain among women with obesity. Furthermore, low body mass index and insufficient gestational weight gain are associated with poor perinatal outcomes. Observational data have shown that first-trimester gain is the strongest predictor of adverse outcomes. Interventions beginning in early pregnancy or preconception are needed to prevent downstream complications for mothers and their children. For neonates, human milk provides personalized nutrition and is associated with short- and long-term health benefits for infants and mothers. Eating a healthy diet is a way for lactating mothers to support optimal health for themselves and their infants.

Enhanced Sp1/YY1 Expression Directs CBS Transcription to Mediate VEGF-Stimulated Pregnancy-Dependent H2S Production in Human Uterine Artery Endothelial Cells

[Figure: see text].

Novel Technologies for Target Delivery of Therapeutics to the Placenta during Pregnancy: A Review

Uterine spiral artery remodeling is essential for placental perfusion and fetal growth and, when impaired, results in placental ischemia and pregnancy complications, e.g., fetal growth restriction, preeclampsia, premature birth. Despite the high incidence of adverse pregnancies, current treatment options are limited. Accordingly, research has shifted to the development of gene therapy technologies that provide targeted delivery of "payloads" to the placenta while limiting maternal and fetal exposure. This review describes the current strategies, including placental targeting peptide-bound liposomes, nanoparticle or adenovirus constructs decorated with specific peptide sequences and placental gene promoters delivered via maternal IV injection, directly into the placenta or the uterine artery, as well as noninvasive site-selective targeting of regulating genes conjugated with microbubbles via contrast-enhanced ultrasound. The review also provides a perspective on the effectiveness of these technologies in various animal models and their practicability and potential use for targeted placental delivery of therapeutics and genes in adverse human pregnancies affected by placental dysfunction.

Blood biomarkers for neonatal hypoxic-ischemic encephalopathy in the presence and absence of sentinel events

OBJECTIVE

To determine if neonatal serum biomarkers representing different pathways of injury differ for cases of HIE of unknown cause to gain insight into timing and mechanism of injury.

STUDY DESIGN

In this cohort of all neonates with HIE admitted to our NICU, newborns with sentinel events were compared to those without during the 1st 3 days of life. Discard neonatal blood during the 1st 3 days of life was used for analysis.

RESULTS

Of 277 babies with HIE treated with whole-body hypothermia, 190 (68.6%) had blood available for biomarker analysis. In total, 71 (37.4%) were born within our system, and 119 (62.6%) were transferred in from outside hospitals. Of these babies, 77 (40.5%) had a sentinel event and 113 (59.6%) had no sentinel event. Although the degree of metabolic acidosis was similar, repeated measures analysis showed that during the initial 3 days of life neonates born with HIE in the absence of sentinel events had 41.4% decreased VEGF (p = 0.027) and 62.5% increased IL-10 serum concentrations (p = 0.005).

CONCLUSION

These changes indicate that neonatal HIE in the absence of sentinel events is not related to an unrecognized acute intrapartum event and is possibly related to chronic hypoxia of lower severity or recovery from a remote event.

First-Trimester Platelet Count as a Predictive Biomarker for Neonatal Birth Weight Among Pregnant Women at Advanced Maternal Age

The aim of this study was to investigate the association between first-trimester platelet count and neonatal birth weight in pregnant woman at advanced maternal age. Our study included 148 pregnancy women of advanced maternal age, the clinical and laboratory materials were retrospective obtained from medical record system. The neonatal birth weight was positively correlated with maternal body mass index and fetus gestational age (r = 0.332, P < .001; r = 0.469, P < .001), even more interestingly, the neonatal birth weight was positively correlated with first-trimester platelet count in pregnant women of advanced maternal age (r = 0.203, P = .013). Multiple linear regression analysis revealed that neonatal birth weight had an independently association with first-trimester platelet count in pregnant women of advanced maternal age (multiple-adjusted r values 0.167, P = .013). First-trimester platelet count is positively associated with neonatal birth weight, suggesting that first-trimester platelet count may be a predictive biomarker for neonatal birth weight in pregnant women of advanced maternal age.

The promise of placental extracellular vesicles: models and challenges for diagnosing placental dysfunction in utero†

Monitoring the health of a pregnancy is of utmost importance to both the fetus and the mother. The diagnosis of pregnancy complications typically occurs after the manifestation of symptoms, and limited preventative measures or effective treatments are available. Traditionally, pregnancy health is evaluated by analyzing maternal serum hormone levels, genetic testing, ultrasonographic imaging, and monitoring maternal symptoms. However, researchers have reported a difference in extracellular vesicle (EV) quantity and cargo between healthy and at-risk pregnancies. Thus, placental EVs (PEVs) may help to understand normal and aberrant placental development, monitor pregnancy health in terms of developing placental pathologies, and assess the impact of environmental influences, such as infection, on pregnancy. The diagnostic potential of PEVs could allow for earlier detection of pregnancy complications via noninvasive sampling and frequent monitoring. Understanding how PEVs serve as a means of communication with maternal cells and recognizing their potential utility as a readout of placental health have sparked a growing interest in basic and translational research. However, to date, PEV research with animal models lags behind human studies. The strength of animal pregnancy models is that they can be used to assess placental pathologies in conjunction with isolation of PEVs from fluid samples at different time points throughout gestation. Assessing PEV cargo in animals within normal and complicated pregnancies will accelerate the translation of PEV analysis into the clinic for potential use in prognostics. We propose that appropriate animal models of human pregnancy complications must be established in the PEV field.

Comparison of Efficiency and Function of Vascular Endothelial Growth Factor Adenovirus Vectors in Endothelial Cells for Gene Therapy of Placental Insufficiency

Severe fetal growth restriction (FGR) affects 1:500 pregnancies, is untreatable and causes serious neonatal morbidity and death. Reduced uterine blood flow (UBF) and lack of bioavailable VEGF due to placental insufficiency is a major cause. Transduction of uterine arteries in normal or FGR sheep and guinea pigs using an adenovirus (Ad) encoding VEGF isoforms A (Ad.VEGF-A165) and a FLAG-tagged pre-processed short form D (DΔNΔC, Ad.VEGF-DΔNΔC-FLAG) increases endothelial nitric oxide expression, enhances relaxation and reduces constriction of the uterine arteries and their branches. UBF and angiogenesis are increased long term, improving fetal growth in utero. For clinical trial development we compared Ad.VEGF vector transduction efficiency and function in endothelial cells (ECs) derived from different species. We aimed to compare the transduction efficiency and function of the pre-clinical study Ad. constructs (Ad.VEGF-A165, Ad.VEGF-DΔNΔC-FLAG) with the intended clinical trial construct (Ad.VEGF-DΔNΔC) where the FLAG tag is removed. We infected ECs from human umbilical vein, pregnant sheep uterine artery, pregnant guinea pig aorta and non-pregnant rabbit aorta, with increasing multiplicity of infection (MOI) for 24 or 48 hours of three Ad.VEGF vectors, compared to control Ad. containing the LacZ gene (Ad.LacZ). VEGF supernatant expression was analysed by ELISA. Functional assessment used tube formation assay and Erk-Akt phosphorylation by ELISA. VEGF expression was higher after Ad.VEGF-DΔNΔC-FLAG and Ad.VEGF-DΔNΔC transduction compared to Ad.VEGF-A165 in all EC types (*p < 0.001). Tube formation was higher in ECs transduced with Ad.VEGF-DΔNΔC in all species compared to other constructs (***p < 0.001, *p < 0.05 with rabbit aortic ECs). Phospho-Erk and phospho-Akt assays displayed no differences between the three vector constructs, whose effect was, as in other experiments, higher than Ad.LacZ (***p < 0.001). In conclusion, we observed high transduction efficiency and functional effects of Ad.VEGF-DΔNΔC vector with comparability in major pathway activation to constructs used in pre-clinical studies, supporting its use in a clinical trial.

Ovine uterine artery hydrogen sulfide biosynthesis in vivo: effects of ovarian cycle and pregnancy†

Uterine vasodilation dramatically increases during the follicular phase of the estrous cycle and pregnancy, which are estrogen-dominant physiological states. Uterine vasodilation is believed to be mainly controlled by local uterine artery (UA) production of vasodilators and angiogenic factors. The extremely potent vasodilator and proangiogenic hydrogen sulfide (H2S) is synthesized via metabolizing L-cysteine by cystathionine β-synthase (CBS) and cystathionine γ-lyase (CTH). This study was designed to determine if UA H2S production increases with augmented expression and/or activity of CBS and/or CTH during the ovarian cycle and pregnancy in sheep. Uterine arteries from intact nonpregnant (NP) luteal and follicular phase and late (130-135 days, term ≈ 145 days) pregnant (P) ewes were collected; endothelium-enriched proteins (UAendo) and endothelium-denuded smooth muscle (UAvsm) were mechanically prepared for accessing CBS and CTH proteins by immunoblotting; their cellular localization was determined by semi-quantitative immunofluorescence microscopy. H2S production was measured by the methylene blue assay. Immunoblotting revealed that CBS but not CTH protein was greater in P > > > NP follicular > luteal UAendo and UAvsm (P < 0.001). H2S production was greater in P > > > NP UAendo and UAvsm (P < 0.01). Pregnancy-augmented UAendo and UAvsm H2S production was inhibited by the specific CBS but not CTH inhibitor. CBS and CTH proteins were localized to both endothelium and smooth muscle; however, only CBS protein was significantly greater in P vs NP UA endothelium and smooth muscle. Thus, ovine UA H2S production is significantly augmented via selectively upregulating endothelium and smooth muscle CBS during the follicular phase and pregnancy in vivo.

Placenta-targeted treatment strategies: An opportunity to impact fetal development and improve offspring health later in life

The Developmental Origins of Health and Disease (DOHaD) theory states that a sub-optimal prenatal and early postnatal environment during development leads to an increased risk of long-term development of adult chronic diseases. Developmental programming of disease has the potential to greatly impact the health of our population. Therefore, research has focused on the development of primary treatment strategies and/or therapeutic interventions for individuals who are at increased risk, with the objective to reverse or prevent later life onset of chronic disease in the offspring born from complicated pregnancies. Many studies have focused on systemic treatments and/or interventions in complicated pregnancies to improve offspring outcomes. However, there are limitations to systemic maternal/prenatal treatments, as most of the treatments are able to cross the placenta and have potential adverse off-target effects on the developing fetus. The placenta serves as the primary interface between mother and fetus, and placental dysfunction in complicated pregnancies has been associated with impaired fetal development and negative impact on offspring health. Therefore, recent research has focused on treatment strategies that specifically target the placenta to improve placental function and prevent passage of prenatal therapeutics and/or treatments into the fetal circulation, thus avoiding any potential adverse off-target effects on the fetus. This article reviews the currently available knowledge on treatment strategies and/or therapeutics that specifically target the placenta with the goal of improving pregnancy outcomes with a focus on long-term health of the offspring born of complicated pregnancies.

Complex, coordinated and highly regulated changes in placental signaling and nutrient transport capacity in IUGR

The most common cause of intrauterine growth restriction (IUGR) in the developed world is placental insufficiency, a concept often used synonymously with reduced utero-placental and umbilical blood flows. However, placental insufficiency and IUGR are associated with complex, coordinated and highly regulated changes in placental signaling and nutrient transport including inhibition of insulin and mTOR signaling and down-regulation of specific amino acid transporters, Na+/K+-ATPase, the Na+/H+-exchanger, folate and lactate transporters. In contrast, placental glucose transport capacity is unaltered and Ca2+-ATPase activity and the expression of proteins involved in placental lipid transport are increased in IUGR. These findings are not entirely consistent with the traditional view that the placenta is dysfunctional in IUGR, but rather suggest that the placenta adapts to reduce fetal growth in response to an inability of the mother to allocate resources to the fetus. This new model has implications for the understanding of the mechanisms underpinning IUGR and for the development of intervention strategies.

The impact of prenatal environment on postnatal life and performance: Future perspectives for prevention and treatment

The present review aims to offer a non-comprehensive outline of the current state-of-the-art and future perspectives on management and therapeutic tools for intrauterine growth restriction (IUGR) and associated prenatal programming in both human and animal species. Animals are used as models for the study of phenomena related to IUGR, but also for research on prenatal therapies with the main objective of designing and developing preventive and therapeutic strategies. The research is currently paying attention on maternal-focused pharmacological treatments and nutritional strategies but also on fetal-focused treatments. Fetal-focused treatments, administered either directly at the fetus or by using infusion of umbilical cord, amniotic sac or placenta, which avoids the administration of substances at high doses to the mother for allowing their availability at the fetoplacental level. The results obtained in this area of research using large animals (rabbits, pigs and ruminants) have a dual interest, for translational biomedicine and for veterinary medicine and animal production.

Placental MRI and its application to fetal intervention

OBJECTIVE

Magnetic resonance imaging (MRI) of placental invasion has been part of clinical practice for many years. The possibility of being better able to assess placental vascularization and function using MRI has multiple potential applications. This review summarises up-to-date research on placental function using different MRI modalities.

METHOD

We discuss how combinations of these MRI techniques have much to contribute to fetal conditions amenable for therapy such as singletons at high risk for fetal growth restriction (FGR) and monochorionic twin pregnancies for planning surgery and counselling for selective growth restriction and transfusion conditions.

RESULTS

The whole placenta can easily be visualized on MRI, with a clear boundary against the amniotic fluid, and a less clear placental-uterine boundary. Contrasts such as diffusion weighted imaging, relaxometry, blood oxygenation level dependent MRI and flow and metabolite measurement by dynamic contrast enhanced MRI, arterial spin labeling, or spectroscopic techniques are contributing to our wider understanding of placental function.

CONCLUSION

The future of placental MRI is exciting, with the increasing availability of multiple contrasts and new models that will boost the capability of MRI to measure oxygen saturation and placental exchange, enabling examination of placental function in complicated pregnancies.

In Utero Gene Therapy (IUGT) Using GLOBE Lentiviral Vector Phenotypically Corrects the Heterozygous Humanised Mouse Model and Its Progress Can Be Monitored Using MRI Techniques

In utero gene therapy (IUGT) to the fetal hematopoietic compartment could be used to treat congenital blood disorders such as β-thalassemia. A humanised mouse model of β-thalassemia was used, in which heterozygous animals are anaemic with splenomegaly and extramedullary hematopoiesis. Intrahepatic in utero injections of a β globin-expressing lentiviral vector (GLOBE), were performed in fetuses at E13.5 of gestation. We analysed animals at 12 and 32 weeks of age, for vector copy number in bone marrow, peripheral blood liver and spleen and we performed integration site analysis. Compared to noninjected heterozygous animals IUGT normalised blood haemoglobin levels and spleen weight. Integration site analysis showed polyclonality. The left ventricular ejection fraction measured using magnetic resonance imaging (MRI) in treated heterozygous animals was similar to that of normal non-β-thalassemic mice but significantly higher than untreated heterozygous thalassemia mice suggesting that IUGT ameliorated poor cardiac function. GLOBE LV-mediated IUGT normalised the haematological and anatomical phenotype in a heterozygous humanised model of β-thalassemia.

Competition for nutrients in pregnant adolescents: consequences for maternal, conceptus and offspring endocrine systems

The competition for nutrients that arises when pregnancy coincides with continuing or incomplete growth in young adolescent girls increases the risk of preterm delivery and low birthweight with negative after-effects for mother and child extending beyond the perinatal period. Sheep paradigms involving nutritional management of weight and adiposity in young, biologically immature adolescents have allowed the consequences of differential maternal growth status to be explored. Although nutrient reserves at conception play a modest role, it is the dietary manipulation of the maternal growth trajectory thereafter which has the most negative impact on pregnancy outcome. Overnourishing adolescents to promote rapid maternal growth is particularly detrimental as placental growth, uteroplacental blood flows and fetal nutrient delivery are perturbed leading to a high incidence of fetal growth restriction and premature delivery of low birthweight lambs, whereas in undernourished adolescents further maternal growth is prevented, and depletion of the maternal body results in a small reduction in birthweight independent of placental size. Maternal and placental endocrine systems are differentially altered in both paradigms with downstream effects on fetal endocrine systems, organ development and body composition. Approaches to reverse these effects have been explored, predominantly targeting placental growth or function. After birth, growth-restricted offspring born to overnourished adolescents and fed to appetite have an altered metabolic phenotype which persists into adulthood, whereas offspring of undernourished adolescents are largely unaffected. This body of work using ovine paradigms has public health implications for nutritional advice offered to young adolescents before and during pregnancy, and their offspring thereafter.

Pregnant women's experiences and perceptions of participating in the EVERREST prospective study; a qualitative study

BACKGROUND

The EVERREST Prospective Study is a multicentre observational cohort study of pregnancies affected by severe early-onset fetal growth restriction. The study recruits women with singleton pregnancies where the estimated fetal weight is less than the 3rd centile and below 600 g, between 20 + 0 and 26 + 6 weeks of pregnancy, in the absence of a known chromosomal, structural or infective cause.

METHOD

The reported study was retrospective descriptive qualitative interview study of women who had participated in the EVERREST Prospective Study. The aim of this study was to explore the experiences and perceptions of pregnant women taking part in research during a pregnancy affected by severe early-onset fetal growth restriction. Audio-recorded semi-structured telephone interviews were conducted with a purposive sample of 12 women, at least 1 year after delivery of their baby. Two of these pregnancies had ended in stillbirth and one in neonatal death, reflecting the outcomes seen in the EVERREST Prospective Study. Participants gave informed consent, were 16 years or older and were interviewed in English. A topic guide was used to ensure a consistent approach. Questions focused on pregnancy experiences, involvement with the EVERREST study and potential involvement in future research. Recordings were transcribed verbatim for thematic analysis using NVivo10.

RESULTS

Four broad themes were identified; 'before joining the EVERREST Prospective Study', 'participating in research', 'information and support' and 'looking back and looking forwards'. Each broad theme incorporated several subthemes. All participants recalled their reaction to being told their baby was smaller than expected. The way this news was given had a lasting impact. A range of benefits of participation in the EVERREST Prospective Study were described and the participants were positive about the way it was conducted. As a consequence, they were receptive to participating in future research. However, the findings suggest that research teams should be sensitive when approaching families at a difficult time or when they are already participating in other research.

CONCLUSIONS

This study highlights the willingness of pregnant women to participate in research and identifies strategies for researchers to engage participants.

Perinatal and long-term effects of maternal uterine artery adenoviral VEGF-A165 gene therapy in the growth-restricted guinea pig fetus

Uterine artery application of adenoviral vascular endothelial growth factor A₁₆₅ (Ad.VEGF-A₁₆₅) gene therapy increases uterine blood flow and fetal growth in experimental animals with fetal growth restriction (FGR). Whether Ad.VEGF-A₁₆₅ reduces lifelong cardiovascular disease risk imposed by FGR remains unknown. Here, pregnant guinea pigs fed 70% normal food intake to induce FGR received Ad.VEGF-A₁₆₅ (1×10¹⁰ viral particles, n = 15) or vehicle ( n = 10), delivered to the external surface of the uterine arteries, in midpregnancy. Ad libitum-fed controls received vehicle only ( n = 14). Litter size, gestation length, and perinatal mortality were similar in control, untreated FGR, and FGR+Ad.VEGF-A₁₆₅ animals. When compared with controls, birth weight was lower in male but higher in female pups following maternal nutrient restriction, whereas both male and female FGR+Ad.VEGF-A₁₆₅ pups were heavier than untreated FGR pups ( P < 0.05, ANOVA). Postnatal weight gain was 10-20% greater in female FGR+Ad.VEGF-A₁₆₅ than in untreated FGR pups, depending on age, although neither group differed from controls. Maternal nutrient restriction reduced heart weight in adult female offspring irrespective of Ad.VEGF-A₁₆₅ treatment but did not alter ventricular wall thickness. In males, postnatal weight gain and heart morphology were not affected by maternal treatment. Neither systolic, diastolic, mean arterial pressure, adrenal weight, nor basal or challenged plasma cortisol were affected by maternal undernutrition or Ad.VEGF-A₁₆₅ in either sex. Therefore, increased fetal growth conferred by maternal uterine artery Ad.VEGF-A₁₆₅ is sustained postnatally in FGR female guinea pigs. In this study, we did not find evidence for an effect of maternal nutrient restriction or Ad.VEGF-A₁₆₅ therapy on adult offspring blood pressure.

Screening for fetal growth restriction and placental insufficiency

Fetal growth restriction (FGR) continues to be a leading cause of preventable stillbirth and poor neurodevelopmental outcomes in offspring, and furthermore is strongly associated with the obstetrical complications of iatrogenic preterm birth and pre-eclampsia. The terms small for gestational age (SGA) and FGR have, for too long, been considered equivalent and therefore used interchangeably. However, the delivery of improved clinical outcomes requires that clinicians effectively distinguish fetuses that are pathologically growth-restricted from those that are constitutively small. A greater understanding of the multifactorial pathogenesis of both early- and late-onset FGR, especially the role of underlying placental pathologies, may offer insight into targeted treatment strategies that preserve placental function. The new maternal blood biomarker placenta growth factor offers much potential in this context. This review highlights new approaches to effective screening for FGR based on a comprehensive review of: etiology, diagnosis, antenatal surveillance and management. Recent advances in novel imaging methods provide the basis for stepwise multi-parametric testing that may deliver cost-effective screening within existing antenatal care systems.

In Vitro Human Placental Studies to Support Adenovirus-Mediated VEGF-DΔNΔC Maternal Gene Therapy for the Treatment of Severe Early-Onset Fetal Growth Restriction

Severe fetal growth restriction (FGR) affects 1 in 500 pregnancies, is untreatable, and causes serious neonatal morbidity and death. Reduced uterine blood flow (UBF) is one cause. Transduction of uterine arteries in normal and FGR animal models using an adenovirus (Ad) encoding VEGF isoforms increases UBF and improves fetal growth in utero. Understanding potential adverse consequences of this therapy before first-in-woman clinical application is essential. The aims of this study were to determine whether Ad.VEGF-D^ΔNΔC (1) transfers across the human placental barrier and (2) affects human placental morphology, permeability and primary indicators of placental function, and trophoblast integrity. Villous explants from normal term human placentas were treated with Ad.VEGF-D^ΔNΔC (5 × 10^7-10 virus particles [vp]/mL), or virus formulation buffer (FB). Villous structural integrity (hematoxylin and eosin staining) and tissue accessibility (LacZ immunostaining) were determined. Markers of endocrine function (human chorionic gonadotropin [hCG] secretion) and cell death (lactate dehydrogenase [LDH] release) were assayed. Lobules from normal and FGR pregnancies underwent ex vivo dual perfusion with exposure to 5 × 10¹⁰ vp/mL Ad.VEGF-D^ΔNΔC or FB. Perfusion resistance, para-cellular permeability, hCG, alkaline phosphatase, and LDH release were measured. Ad.VEGF-D^ΔNΔC transfer across the placental barrier was assessed by quantitative polymerase chain reaction in DNA extracted from fetal-side venous perfusate, and by immunohistochemistry in fixed tissue. Villous explant structural integrity and hCG secretion was maintained at all Ad.VEGF-D^ΔNΔC doses. Ad.VEGF-D^ΔNΔC perfusion revealed no effect on placental permeability, fetoplacental vascular resistance, hCG secretion, or alkaline phosphatase release, but there was a minor elevation in maternal-side LDH release. Viral vector tissue access in both explant and perfused models was minimal, and the vector was rarely detected in the fetal venous perfusate and at low titer. Ad.VEGF-D^ΔNΔC did not markedly affect human placental integrity and function in vitro. There was limited tissue access and transfer of vector across the placental barrier. Except for a minor elevation in LDH release, these test data did not reveal any toxic effects of Ad.VEGF-D^ΔNΔC on the human placenta.

The role of aspirin, heparin, and other interventions in the prevention and treatment of fetal growth restriction

Fetal growth restriction and related placental pathologies such as preeclampsia, stillbirth, and placental abruption are believed to arise in early pregnancy when inadequate remodeling of the maternal spiral arteries leads to persistent high-resistance and low-flow uteroplacental circulation. The consequent placental ischaemia, reperfusion injury, and oxidative stress are associated with an imbalance in angiogenic/antiangiogenic factors. Many interventions have centered on the prevention and/or treatment of preeclampsia with results pertaining to fetal growth restriction and small-for-gestational-age pregnancy often included as secondary outcomes because of the common pathophysiology. This renders the study findings less reliable for determining clinical significance. For the prevention of fetal growth restriction, a recent large-study level meta-analysis and individual patient data meta-analysis confirm that aspirin modestly reduces small-for-gestational-age pregnancy in women at high risk (relative risk, 0.90, 95% confidence interval, 0.81-1.00) and that a dose of ≥100 mg should be recommended and to start at or before 16 weeks of gestation. These findings support national clinical practice guidelines. In vitro and in vivo studies suggest that low-molecular-weight heparin may prevent fetal growth restriction; however, evidence from randomized control trials is inconsistent. A meta-analysis of multicenter trial data does not demonstrate any positive preventative effect of low-molecular-weight heparin on a primary composite outcome of placenta-mediated complications including fetal growth restriction (18% vs 18%; absolute risk difference, 0.6%; 95% confidence interval, 10.4-9.2); use of low-molecular-weight heparin for the prevention of fetal growth restriction should remain in the research setting. There are even fewer treatment options once fetal growth restriction is diagnosed. At present the only management option if the risk of hypoxia, acidosis, and intrauterine death is high is iatrogenic preterm birth, with the use of peripartum maternal administration of magnesium sulphate for neuroprotection and corticosteroids for fetal lung maturity, to prevent adverse neonatal outcomes. The pipeline of potential therapies use different strategies, many aiming to increase fetal growth by improving poor placentation and uterine blood flow. Phosphodiesterase type 5 inhibitors that potentiate nitric oxide availability such as sildenafil citrate have been extensively researched both in preclinical and clinical studies; results from the Sildenafil Therapy In Dismal Prognosis Early-Onset Intrauterine Growth Restriction consortium of randomized control clinical trials are keenly awaited. Targeting the uteroplacental circulation with novel therapeutics is another approach, the most advanced being maternal vascular endothelial growth factor gene therapy, which is being translated into the clinic via the doEs Vascular endothelial growth factor gene therapy safEly impRove outcome in seveRe Early-onset fetal growth reSTriction consortium. Other targeting approaches include nanoparticles and microRNAs to deliver drugs locally to the uterine arterial endothelium or trophoblast. In vitro and in vivo studies and animal models have demonstrated effects of nitric oxide donors, dietary nitrate, hydrogen sulphide donors, statins, and proton pump inhibitors on maternal blood pressure, uteroplacental resistance indices, and angiogenic/antiangiogenic factors. Data from human pregnancies and, in particular, pregnancies with fetal growth restriction remain very limited. Early research into melatonin, creatine, and N-acetyl cysteine supplementation in pregnancy suggests they may have potential as neuro- and cardioprotective agents in fetal growth restriction.

Placenta-directed gene therapy for fetal growth restriction

Fetal growth restriction (FGR) is a serious pregnancy complication affecting ∼8% of all pregnancies. There is no treatment to increase fetal growth in the uterus. Gene therapy presents a promising treatment strategy for FGR, with the use of adenoviral vectors encoding for proteins such as vascular endothelial growth factor (VEGF) and insulin-like growth factor demonstrating improvements in fetal growth, placental function, and neonatal outcome in preclinical studies. Safety assessments suggest no adverse risk to the mother or fetus for VEGF maternal gene therapy; a clinical trial is in development. This review assesses research into placenta-directed gene therapy for FGR, investigating the use of transgenes and vectors, their route of administration in obstetrics, and the steps that will be needed to take this treatment modality into the clinic.

Treating the dysfunctional placenta

Placental dysfunction underlies major obstetric diseases such as pre-eclampsia and fetal growth restriction (FGR). Whilst there has been a little progress in prophylaxis, there are still no treatments for placental dysfunction in normal obstetric practice. However, a combination of increasingly well-described in vitro systems for studying the human placenta, together with the availability of more appropriate animal models of pre-eclampsia and FGR, has facilitated a recent surge in work aimed at repurposing drugs and therapies, developed for other conditions, as treatments for placental dysfunction. This review: (1) highlights potential candidate drug targets in the placenta - effectors of improved uteroplacental blood flow, anti-oxidants, heme oxygenase induction, inhibition of HIF, induction of cholesterol synthesis pathways, increasing insulin-like growth factor II availability; (2) proposes an experimental pathway for taking a potential drug or treatment for placental dysfunction from concept through to early phase clinical trials, utilizing techniques for studying the human placenta in vitro and small animal models, particularly the mouse, for in vivo studies; (3) describes the data underpinning sildenafil citrate and adenovirus expressing vascular endothelial growth as potential treatments for placental dysfunction and summarizes recent research on other potential treatments. The importance of sharing information from such studies even when no effect is found, or there is an adverse outcome, is highlighted. Finally, the use of adenoviral vectors or nanoparticle carriers coated with homing peptides to selectively target drugs to the placenta is highlighted: such delivery systems could improve efficacy and reduce the side effects of treating the dysfunctional placenta.

EVERREST prospective study: a 6-year prospective study to define the clinical and biological characteristics of pregnancies affected by severe early onset fetal growth restriction

BACKGROUND

Fetal growth restriction (FGR) is a serious obstetric condition for which there is currently no treatment. The EVERREST Prospective Study has been designed to characterise the natural history of pregnancies affected by severe early onset FGR and establish a well phenotyped bio-bank. The findings will provide up-to-date information for clinicians and patients and inform the design and conduct of the EVERREST Clinical Trial: a phase I/IIa trial to assess the safety and efficacy of maternal vascular endothelial growth factor (VEGF) gene therapy in severe early onset FGR. Data and samples from the EVERREST Prospective Study will be used to identify ultrasound and/or biochemical markers of prognosis in pregnancies with an estimated fetal weight (EFW) <3rd centile between 20+0 and 26+6 weeks of gestation.

METHODS

This is a 6 year European multicentre prospective cohort study, recruiting women with a singleton pregnancy where the EFW is <3rd centile for gestational age and <600 g at 20+0 to 26+6 weeks of gestation. Detailed data are collected on: maternal history; antenatal, peripartum, and postnatal maternal complications; health economic impact; psychological impact; neonatal condition, progress and complications; and infant growth and neurodevelopment to 2 years of corrected age in surviving infants. Standardised longitudinal ultrasound measurements are performed, including: fetal biometry; uterine artery, umbilical artery, middle cerebral artery, and ductus venosus Doppler velocimetry; and uterine artery and umbilical vein volume blood flow. Samples of maternal blood and urine, amniotic fluid (if amniocentesis performed), placenta, umbilical cord blood, and placental bed (if caesarean delivery performed) are collected for bio-banking. An initial analysis of maternal blood samples at enrolment is planned to identify biochemical markers that are predictors for fetal or neonatal death.

DISCUSSION

The findings of the EVERREST Prospective Study will support the development of a novel therapy for severe early onset FGR by describing in detail the natural history of the disease and by identifying women whose pregnancies have the poorest outcomes, in whom a therapy might be most advantageous. The findings will also enable better counselling of couples with affected pregnancies, and provide a valuable resource for future research into the causes of FGR.

TRIAL REGISTRATION

NCT02097667 registered 31^st October 2013.

EVERREST prospective study: a 6-year prospective study to define the clinical and biological characteristics of pregnancies affected by severe early onset fetal growth restriction

Background

Fetal growth restriction (FGR) is a serious obstetric condition for which there is currently no treatment. The EVERREST Prospective Study has been designed to characterise the natural history of pregnancies affected by severe early onset FGR and establish a well phenotyped bio-bank. The findings will provide up-to-date information for clinicians and patients and inform the design and conduct of the EVERREST Clinical Trial: a phase I/IIa trial to assess the safety and efficacy of maternal vascular endothelial growth factor (VEGF) gene therapy in severe early onset FGR. Data and samples from the EVERREST Prospective Study will be used to identify ultrasound and/or biochemical markers of prognosis in pregnancies with an estimated fetal weight (EFW) <3rd centile between 20+0 and 26+6 weeks of gestation.

Methods

This is a 6 year European multicentre prospective cohort study, recruiting women with a singleton pregnancy where the EFW is <3rd centile for gestational age and <600 g at 20+0 to 26+6 weeks of gestation. Detailed data are collected on: maternal history; antenatal, peripartum, and postnatal maternal complications; health economic impact; psychological impact; neonatal condition, progress and complications; and infant growth and neurodevelopment to 2 years of corrected age in surviving infants. Standardised longitudinal ultrasound measurements are performed, including: fetal biometry; uterine artery, umbilical artery, middle cerebral artery, and ductus venosus Doppler velocimetry; and uterine artery and umbilical vein volume blood flow. Samples of maternal blood and urine, amniotic fluid (if amniocentesis performed), placenta, umbilical cord blood, and placental bed (if caesarean delivery performed) are collected for bio-banking. An initial analysis of maternal blood samples at enrolment is planned to identify biochemical markers that are predictors for fetal or neonatal death.

Discussion

The findings of the EVERREST Prospective Study will support the development of a novel therapy for severe early onset FGR by describing in detail the natural history of the disease and by identifying women whose pregnancies have the poorest outcomes, in whom a therapy might be most advantageous. The findings will also enable better counselling of couples with affected pregnancies, and provide a valuable resource for future research into the causes of FGR.

Trial registration

NCT02097667 registered 31^st October 2013.

Electronic supplementary material

The online version of this article (doi:10.1186/s12884-017-1226-7) contains supplementary material, which is available to authorized users.

Adaptability and potential for treatment of placental functions to improve embryonic development and postnatal health

For an organ that is so critical for life in eutherian mammals, the placenta hardly gets the attention that it deserves. The placenta does a series of remarkable things, including implanting the embryo in the uterus, negotiating with the mother for nutrients but also protecting her health during pregnancy, helping establish normal metabolic and cardiovascular function for life postnatally (developmental programming) and initiating changes that prepare the mother to care for and suckle her young after birth. Different lines of evidence in experimental animals suggest that the development and function of the placenta are adaptable. This means that some of the changes observed in pathological pregnancies may represent attempts to mitigate the impact of fetal growth and development. Key and emerging concepts are reviewed here concerning how we may view the placenta diagnostically and therapeutically in pregnancy complications, focusing on information from experimental studies in mice, sheep and cattle, as well as association studies from humans. Hundreds of different genes have been shown to underlie normal placental development and function, some of which have promise as tractable targets for intervention in pregnancies at risk for poor fetal growth.

Maternal Therapy with Ad.VEGF-A165 Increases Fetal Weight at Term in a Guinea-Pig Model of Fetal Growth Restriction

In a model of growth-restricted sheep pregnancy, it was previously demonstrated that transient uterine artery VEGF overexpression can improve fetal growth. This approach was tested in guinea-pig pregnancies, where placental physiology is more similar to humans. Fetal growth restriction (FGR) was attained through peri-conceptual nutrient restriction in virgin guinea pigs. Ad.VEGF-A₁₆₅ or Ad.LacZ (1 × 10¹⁰vp) was applied at mid-gestation via laparotomy, delivered externally to the uterine circulation with thermosensitive gel. At short-term (3-8 days post surgery) or at term gestation, pups were weighed, and tissues were sampled for vector spread analysis, VEGF expression, and its downstream effects. Fetal weight at term was increased (88.01 ± 13.36 g; n = 26) in Ad.VEGF-A₁₆₅-treated animals compared with Ad.LacZ-treated animals (85.52 ± 13.00 g; n = 19; p = 0.028). The brain, liver, and lung weight and crown rump length were significantly larger in short-term analyses, as well as VEGF expression in transduced tissues. At term, molecular analyses confirmed the presence of VEGF transgene in target tissues but not in fetal samples. Tissue histology analysis and blood biochemistry/hematological examination were comparable with controls. Uterine artery relaxation in Ad.VEGF-A₁₆₅-treated dams was higher compared with Ad.LacZ-treated dams. Maternal uterine artery Ad.VEGF-A₁₆₅ increases fetal growth velocity and term fetal weight in growth-restricted guinea-pig pregnancy.

The use of ultrasound to assess fetal growth in a guinea pig model of fetal growth restriction

Fetal growth restriction (FGR) is a common and potentially severe pregnancy complication. Currently there is no treatment available. The guinea pig is an attractive model of human pregnancy as placentation is morphologically very similar between the species. Nutrient restriction of the dam creates growth-restricted fetuses while leaving an intact uteroplacental circulation, vital for evaluating novel therapies for FGR. Growth-restricted fetuses were generated by feeding Dunkin Hartley guinea pig dams 70% of ad libitum intake from four weeks before and throughout pregnancy. The effect of maternal nutrient restriction (MNR) on dams and fetuses was carefully monitored, and ultrasound measurements of pups collected. There was no difference in maternal weight at conception, however by five weeks post conception MNR dams were significantly lighter ( P < 0.05). MNR resulted in significantly smaller pup size from 0.6-0.66 gestation. Ultrasound is a powerful non-invasive tool for assessing the effect of therapeutic interventions on fetal growth, allowing longitudinal measurement of fetuses. This model and method yield data applicable to the human condition without the need for animal sacrifice and will be useful in the translation of therapies for FGR into the clinic.

Peri- and Postnatal Effects of Prenatal Adenoviral VEGF Gene Therapy in Growth-Restricted Sheep

Uterine artery (UtA) adenovirus (Ad) vector-mediated overexpression of vascular endothelial growth factor (VEGF) enhances uterine blood flow in normal sheep pregnancy and increases fetal growth in the overnourished adolescent sheep model of fetal growth restriction (FGR). Herein, we examined its impact on gestation length, neonatal survival, early postnatal growth and metabolism. Singleton-bearing ewes were evenly allocated to receive Ad.VEGF-A165 (5 × 10(10) particles/ml, 10 ml, n = 17) or saline (10 ml, n = 16) injected into each UtA at laparotomy (0.6 gestation). Fetal growth was serially monitored (blind) by ultrasound until delivery. Lambs were weighed and blood was sampled weekly and a glucose tolerance test performed (68-day postnatal age). Hepatic DNA/RNA was extracted at necropsy (83-day postnatal age) to examine methylation status of eight somatotropic axis genes. IGF1 mRNA and protein expression were measured by RT-PCR and radioimmunoassay, respectively. All pregnancies remained viable following Ad.VEGF-A165 treatment. Fetal abdominal circumference and renal volume were greater in the Ad.VEGF-A165 group compared with the saline group at 21/28 days (P ≤ 0.04) postinjection. At delivery, gestation length (P = 0.07), lamb birthweight (P = 0.08), umbilical girth (P = 0.06), and plasma glucose (P = 0.09) tended to be greater in Ad.VEGF-A165-treated lambs. Levels of neonatal intervention required to ensure survival was equivalent between groups. Absolute postnatal growth rate (P = 0.02), insulin area under the curve (P = 0.04) and carcass weight at necropsy (P = 0.04) were increased by Ad.VEGF-A165 treatment. There was no impact on markers of insulin sensitivity or methylation/expression of key genes involved in somatic growth. Ad.VEGF-A165 gene therapy increased fetal growth in a sheep FGR model, and lambs continued to thrive during the neonatal and early postnatal period.

Ethics and social acceptability of a proposed clinical trial using maternal gene therapy to treat severe early-onset fetal growth restriction

OBJECTIVE

To evaluate the ethical and social acceptability of a proposed clinical trial using maternal uterine artery vascular endothelial growth factor (VEGF) gene therapy to treat severe early-onset fetal growth restriction (FGR) in pregnant women.

METHODS

We conducted a literature review on the ethics and legality of experimental treatments in pregnant women, in particular advanced therapeutics. Issues that were identified from the literature helped develop interview guides for semistructured, qualitative interviews, carried out in four European countries, with 34 key stakeholders (disability groups, professional bodies and patient support groups) and 24 women/couples who had experienced a pregnancy affected by severe early-onset FGR.

RESULTS

The literature review identified two main questions: 'is it ethical to give a pregnant woman a potentially risky treatment from which she does not benefit directly?' and 'is it ethical to treat a condition of the unborn child, who may then be born with a serious disability when, without treatment, they would have died?'. The review concluded that there were no ethical or legal objections to the intervention, or to a trial of this intervention. Overall, respondents viewed the proposed trial in positive terms. Women were generally interested in participating in clinical trials that conferred a potential benefit to their unborn child. The risk of disability of the premature child was a concern, but not considered a major stumbling block for maternal VEGF gene therapy.

CONCLUSIONS

This study did not identify any fundamental or insurmountable objections to a trial of maternal gene therapy for severe early-onset FGR. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Gene Targeting to the Uteroplacental Circulation of Pregnant Guinea Pigs

Our study aimed to target adenoviral gene therapy to the uteroplacental circulation of pregnant guinea pigs in order to develop a novel therapy for fetal growth restriction. Four methods of delivery of an adenovirus encoding β-galactosidase (Ad.LacZ) were evaluated: intravascular injection using phosphate-buffered saline (PBS) into (1) uterine artery (UtA) or (2) internal iliac artery or external administration in (3) PBS or (4) pluronic F-127 gel (Sigma Aldrich). Postmortem examination was performed 4 to 7 days after gene transfer. Tissue transduction was assessed by X-gal histochemistry and enzyme-linked immunosorbent assay. External vascular application of the adenovirus vector in combination with pluronic gel had 91.7% success rate in terms of administration (85% maternal survival) and gave the best results for maternal/fetal survival and local transduction efficiency without any spread to maternal or fetal tissues. This study suggests an optimal method of gene delivery to the UtAs of a small rodent for preclinical studies.

Intraplacental gene therapy with Ad-IGF-1 corrects naturally occurring rabbit model of intrauterine growth restriction

Intrauterine growth restriction (IUGR) due to placental insufficiency is a leading cause of perinatal complications for which there is no effective prenatal therapy. We have previously demonstrated that intraplacental injection of adenovirus-mediated insulin-like growth factor-1 (Ad-IGF-1) corrects fetal weight in a murine IUGR model induced by mesenteric uterine artery branch ligation. This study investigated the effect of intraplacental Ad-IGF-1 gene therapy in a rabbit model of naturally occurring IUGR (runt) due to placental insufficiency, which is similar to the human IUGR condition with onset in the early third trimester, brain sparing, and a reduction in liver weight. Laparotomy was performed on New Zealand White rabbits on day 21 of 30 days of gestation and litters were divided into five groups: Control (first position)+phosphate-buffered saline (PBS), control+Ad-IGF-1, runt (third position)+PBS, runt+Ad-IGF-1, and runt+Ad-LacZ. The effect of IGF-1 gene therapy on fetal, placental, liver, heart, lung, and musculoskeletal weights of the growth-restricted pups was examined. Protein expression after gene transfer was seen along the maternal-fetal placenta interface (n=12) 48 hr after gene therapy. There was minimal gene transfer detected in the pups or maternal organs. At term, compared with the normally grown first-position control, the runted third-position pups demonstrated significantly lower fetal, placental, liver, lung, and musculoskeletal weights. The fetal, liver, and musculoskeletal weights were restored to normal by intraplacental Ad-IGF-1 gene therapy (p<0.01), with no change in the placental weight. Intraplacental gene therapy is a novel strategy for the treatment of IUGR caused by placental insufficiency that takes advantage of an organ that will be discarded at birth. Development of nonviral IGF-1 gene delivery using placenta-specific promoters can potentially minimize toxicity to the mother and fetus and facilitate clinical translation of this novel therapy.