Models of Intrauterine growth restriction and fetal programming in rabbits

An oral developmental toxicity study of generic pesticide pinoxaden in rabbits

The safety assessment of pinoxaden by the Joint Meeting on Pesticide Residues (JMPR) established a NOAEL of 30 mg/kg bw/day for maternal and embryo/fetal toxicity from a rabbit developmental toxicity study. However, the Pesticide Peer Review Expert meeting (EFSA) lowered the NOAEL to 10 mg/kg bw/day due to observed diaphragm malformations in one developmental toxicity study in rabbits, proposing a classification for developmental effects as Category 2 R63 or H361d. Both JMPR and EFSA set the Acceptable Daily Intake (ADI) at 0.1 mg/kg bw/day, derived from a 2-year rat study NOAEL with a safety factor of 100, but EFSA also supported ADI by teratology study in rabbits. The current prenatal developmental toxicity study on pinoxaden aimed to elucidate and clarify the potential teratogenic effects and could provide supplementary data for determining the ADI for pinoxaden. The study design exceeded the OECD TG 414 by including an assessment of internal organs. The test item was orally administered by gavage daily from day 6 to day 28 of gestation to three groups of animals, each composed of 21 females, in dose levels of 0, 10 and 30 mg/kg/bw/day. One female from the 30 mg/kg/bw/day dose group was euthanized in extremis on Day 27 post-coitum due to premature delivery, likely induced by poor general condition and was therefore considered to be an indirect effect of the test item. One female at 30 mg/kg/bw/day had entirely dead litters except for one live male pup (9 non-live implants vs 1 live fetus). Since the incidence of post-implantation loss or mean number of the dead pups within the remaining dams at 30 mg/kg/ bw/day that survived to necropsy was not significantly increased, we assume that the toxic effect was on the dam, rather than on the conceptus. No pinoxaden-related skeletal or visceral variations or malformations were observed. No evidence of developmental toxicity was observed. Under the conditions of the study, the pinoxaden produced maternal toxicity at a high dose tested; thus, NOAEL for maternal toxicity was determined to be 10 mg/kg bw/day. NOAEL for developmental toxicity was established at 30 mg/kg bw/day. The obtained results may supplement the overall safety and toxicity profile of pinoxaden. Nevertheless, the NOAEL determined in this study does not affect the previously established ADI.

Is the rabbit a natural model of fetal growth restriction? Morphological and functional characterization study using diffusion-weighted MRI and stereology

INTRODUCTION

Rabbits are routinely used as a natural model of fetal growth restriction (FGR); however, no studies have confirmed that rabbits have FGR. This study aimed to characterize the fetoplacental unit (FPU) in healthy pregnant rabbits using diffusion-weighted MRI and stereology. A secondary objective of the study was to describe the associations among findings from diffusion-weighted MRI (DW-MRI), fetal weight measurement and histological analysis of the placenta.

METHODS

Pregnant rabbits underwent DW-MRI under general anesthesia on embryonic day 28 of pregnancy. MR imaging was performed at 3.0 T. The apparent diffusion coefficient (ADC) values were calculated for the fetal brain, liver, and placenta. The placenta was analyzed by stereology (volume density of trophoblasts, the maternal blood space and fetal vessels). Each fetus and placenta were weighed. Two groups of fetuses were defined according to the position in the uterine horn (Cervix group versus Ovary group).

RESULTS

We analyzed 20 FPUs from 5 pregnant rabbits. Fetuses and placentas were significantly lighter in the Cervix group than in the Ovary group (34.7 ± 3.7 g vs. 40.2 ± 5.4 g; p = 0.02). Volume density analysis revealed that the percentage of fetal vessels, the maternal blood space and trophoblasts was not significantly affected by the position of the fetus in the uterine horn. There was no difference in ADC values according to the position of the fetus in the uterine horn, and there was no correlation between ADC values and fetal weight.

DISCUSSION

The findings of a multimodal evaluation of the placenta in a rabbit model of FGR suggested is not a natural model of fetal growth restriction.

Selenium Injection in Dam Rabbits During Gestation Has Important Effects on Progeny Productive Performance

Micromineral elements have a fundamental participation in the processes of organogenesis and fetal development. The objective of this study was to assess the effect of selenium (Se) injection in pregnant female rabbits, during organogenesis or rapid fetal growth, on the productive performance of their progeny. An experiment was carried out with 30 New Zealand female rabbits, with an average age of 6 months. At the end of mating (day 0), using a randomized complete design, the female rabbits were distributed into three experimental groups, which were assigned to the following treatments: Control, female rabbits were injected intramuscularly (IM) with 0.5 ml of saline on days 13 and 23 of gestation; Early administration, female rabbits that were injected IM with Se (0.10 mg/kg BW) on day 13 of gestation (organogenesis) and 0.5 ml of saline on day 23 of gestation; and Late administration, female rabbits that were injected IM with 0.5 ml of saline on day 13 of gestation and Se (0.10 mg/kg BW) on day 23 of gestation (rapid fetal growth). No differences were found on kindling performance of dams and pre-weaning growth of rabbit offspring. However, an injection of Se to pregnant rabbits affected the growth and development of their progeny, with the treatment leading to changes in the yield of some carcass traits (forelimb weight and forelimb muscle weight) and weights of some organs (liver, lungs, and spleen). The Se treatment (both early and late) also resulted in lower concentrations of glucose, triglycerides, and cholesterol when compared to the control group. These effects were different when Se injection was performed during organogenesis or rapid fetal development. The results from this study suggest that there are beneficial effects of gestational Se injection of rabbit dams on important productive traits of their progeny.

Perinatal compromise affects development, form, and function of the hippocampus part two; preclinical studies

The hippocampus is a vital brain structure deep in the medial temporal lobe that mediates a range of functions encompassing emotional regulation, learning, memory, and cognition. Hippocampal development is exquisitely sensitive to perturbations and adverse conditions during pregnancy and at birth, including preterm birth, fetal growth restriction (FGR), acute hypoxic-ischaemic encephalopathy (HIE), and intrauterine inflammation. Disruptions to hippocampal development due to these conditions can have long-lasting functional impacts. Here, we discuss a range of preclinical models of prematurity and FGR and conditions that induce hypoxia and inflammation, which have been critical in elucidating the underlying mechanisms and cellular and subcellular structures implicated in hippocampal dysfunction. Finally, we discuss potential therapeutic targets to reduce the burden of these perinatal insults on the developing hippocampus. IMPACT: The review explores the preclinical literature examining the association between pregnancy and birth complications, and hippocampal form and function. The developmental processes and cellular mechanisms that are disrupted within the hippocampus following perinatal compromise are described, and potential therapeutic targets are discussed.

Single nucleotide polymorphisms in the KRT82 promoter region modulate irregular thickening and patchiness in the dorsal skin of New Zealand rabbits

BACKGROUND

While rabbits are used as models in skin irritation tests, the presence of irregular patches and thickening on the dorsal skin can affect precise evaluation. In this study, genes associated with patchiness or non-patchiness on the dorsal skin of New Zealand rabbits were investigated to identify potential regulators of the patchiness phenotype.

RESULTS

The results showed that parameters associated with hair follicles (HFs), such as HF density, skin thickness, and HF depth, were augmented in rabbits with the patchiness phenotype relative to the non-patchiness phenotype. A total of 592 differentially expressed genes (DEGs) were identified between the two groups using RNA-sequencing. These included KRT72, KRT82, KRT85, FUT8, SOX9, and WNT5B. The functions of the DEGs were investigated by GO and KEGG enrichment analyses. A candidate gene, KRT82, was selected for further molecular function verification. There was a significant positive correlation between KRT82 expression and HF-related parameters, and KRT82 overexpression and knockdown experiments with rabbit dermal papilla cells (DPCs) showed that it regulated genes related to skin and HF growth and development. Investigation of single nucleotide polymorphisms (SNPs) in the exons and promoter region of KRT82 identified four SNPs in the promoter region but none in the exons. The G.-631G > T, T.-696T > C, G.-770G > T and A.-873 A > C alleles conformed to the Hardy - Weinberg equilibrium, and three identified haplotypes showed linkage disequilibrium. Luciferase reporter assays showed that the core promoter region of KRT82 was located in the - 600 to - 1200 segment, in which the four SNPs were located.

CONCLUSIONS

The morphological characteristics of the patchiness phenotype were analyzed in New Zealand rabbits and DEGs associated with this phenotype were identified by RNA-sequencing. The biological functions of the gene KRT82 associated with this phenotype were analyzed, and four SNPs were identified in the promoter region of the gene. These findings suggest that KRT82 may be a potential biomarker for the breeding of experimental New Zealand rabbits.

Pregnancy Complications and Feto-Maternal Monitoring in Rabbits

Rabbit production holds significant relevance in modern agriculture due to its potential as a sustainable source of high-quality protein and efficient feed conversion, contributing to food security and economic diversification. Nevertheless, studies incorporating feto-maternal monitoring in this species are uncommon. This review gathers research on the monitoring and evaluation of factors affecting rabbit gestation, providing a better understanding of the causes of prenatal development abnormalities. These include studies regarding how chronic maternal hypertension, gestational diabetes, maternal stress, ectopic gestation, maternal uterine ischemia and fetal hypoxia, intrauterine growth restriction, superfetation, maternal age, maternal nutritional status, maternal physical condition, maternal and embryonic genotype, and the intrauterine location of rabbit fetuses can potentially impact rabbits' reproduction and maternal and fetal health. Among other monitoring techniques, ultrasonography, considered one of the best tools for diagnosing pregnancy and conducting follow-up, is also reviewed. Details on measurable fetal-development parameters in rabbits and precautions to be considered before and during the examination are also provided. Additional studies are required to understand why some events occur and their consequences throughout gestation, allowing the determination of new biomarkers or cut-offs that can be helpful for early diagnosis and improve reproductive efficiency.

The Effects of Prenatal Pravastatin Treatment in the Rabbit Fetal Growth Restriction Model

Fetal growth restriction (FGR) remains without an effective prenatal treatment. Evidence from murine FGR models suggests a beneficial effect of prenatal pravastatin. Since the rabbit hemodichorial placenta more closely resembles the human condition, we investigated the effects of prenatal maternal pravastatin administration in the rabbit FGR model. At a gestational age of 25 days (term 31d), pregnant dams underwent partial uteroplacental vessel ligation (UPVL) in one uterine horn to induce FGR, leaving the other horn as a control. Dams were randomized to either receive 5 mg/kg/d pravastatin dissolved in their drinking water or normal drinking water until delivery. At GA 30d, the rabbits were delivered and were divided into four groups: control without pravastatin (C/NoPrav), FGR without pravastatin (FGR/NoPrav), FGR with pravastatin (FGR/Prav), and controls with pravastatin (C/Prav). The newborn rabbits underwent pulmonary functional assessment and neurobehavioral assessment, and they were harvested for alveolar morphometry or neuropathology. The placentas underwent histology examination and RNA expression. Birth weight was lower in the FGR groups (FGR/Prav, FGR/NoPrav), but there was no difference between FGR/Prav and C/NoPrav. No differences were noted in placental zone proportions, but eNOS in FGR/Prav placentas and VEGFR-2 in FGR/Prav and C/Prav were upregulated. There were no differences in pulmonary function assessment and alveolar morphometry. FGR/Prav kittens had increased neurosensory scores, but there were no differences in neuromotor tests, neuron density, apoptosis, and astrogliosis. In conclusion, in the rabbit FGR model, pravastatin upregulated the expression of VEGFR-2 and eNOS in FGR placentas and was associated with higher neurosensory scores, without measurable effects on birthweight, pulmonary function and morphology, and neuron density.

Hyperglycosylated-hCG: Its Role in Trophoblast Invasion and Intrauterine Growth Restriction

Human chorionic gonadotropin (hCG) is produced by the placenta and its roles have been studied for over a century, being the first known pregnancy-related protein. Although its main role is to stimulate the production of progesterone by corpus luteal cells, hCG does not represent just one biologically active molecule, but a group of at least five variants, produced by different cells and each with different functions. The hyperglycosylated variant of hCG (H-hCG) plays a key role in trophoblast invasion, placental development and fetal growth. During trophoblast invasion, H-hCG promotes extravillous cytotrophoblast cells to infiltrate the decidua, and also to colonize and remodel the spiral arteries in to low resistance, larger-diameter vessels. As fetal growth is heavily reliant on nutrient availability, impaired trophoblast invasion and remodeling of the uterine arteries, leads to a defective perfusion of the placenta and fetal growth restriction. Understanding the function of H-hCG in the evolution of the placenta might unveil new ways to manage and treat fetal growth restriction.

Placental adaptations supporting fetal growth during normal and adverse gestational environments

NEW FINDINGS

What is the topic of this review? How the placenta, which transports nutrients and oxygen to the fetus, may alter its support of fetal growth developmentally and with adverse gestational conditions. What advances does it highlight? Placental formation and function alter with the needs of the fetus for substrates for growth during normal gestation and when there is enhanced competition for substrates in species with multiple gestations or adverse gestational environments, and this is mediated by imprinted genes, signalling pathways, mitochondria and fetal sexomes.

ABSTRACT

The placenta is vital for mammalian development and a key determinant of life-long health. It is the interface between the mother and fetus and is responsible for transporting the nutrients and oxygen a fetus needs to develop and grow. Alterations in placental formation and function, therefore, have consequences for fetal growth and birthweight, which in turn determine perinatal survival and risk of non-communicable diseases for the offspring in later postnatal life. However, the placenta is not a static organ. As this review summarizes, research from multiple species has demonstrated that placental formation and function alter developmentally to the needs of the fetus for substrates for growth during normal gestation, as well as when there is greater competition for substrates in polytocous species and monotocous species with multiple gestations. The placenta also adapts in response to the gestational environment, integrating information about the ability of the mother to provide nutrients and oxygen with the needs of the fetus in that prevailing environment. In particular, placental structure (e.g. vascularity, surface area, blood flow, diffusion distance) and transport capacity (e.g. nutrient transporter levels and activity) respond to suboptimal gestational environments, namely malnutrition, obesity, hypoxia and maternal ageing. Mechanisms mediating developmentally and environmentally induced homeostatic responses of the placenta that help support normal fetal growth include imprinted genes, signalling pathways, subcellular constituents and fetal sexomes. Identification of these placental strategies may inform the development of therapies for complicated human pregnancies and advance understanding of the pathways underlying poor fetal outcomes and their consequences for health and disease risk.

Severe Diabetes Induction as a Generational Model for Growth Restriction of Rat

We used uncontrolled maternal diabetes as a model to provoke fetal growth restriction in the female in the first generation (F₁) and to evaluate reproductive outcomes and the possible changes in metabolic systems during pregnancy, as well as the repercussions at birth in the second generation (F₂). For this, nondiabetic and streptozotocin-induced severely diabetic Sprague-Dawley rats were mated to obtain female pups (F₁), which were classified as adequate (AGA) or small (SGA) for gestational weight. Afterward, we composed two groups: F₁ AGA from nondiabetic dams (Control) and F₁ SGA from severely diabetic dams (Restricted) (n minimum = 10 animals/groups). At adulthood, these rats were submitted to the oral glucose tolerance test, mated, and at day 17 of pregnancy, blood samples were collected to determine glucose and insulin levels for assessment of insulin resistance. At the end of the pregnancy, the blood and liver samples were collected to evaluate redox status markers, and reproductive, fetal, and placental outcomes were analyzed. Maternal diabetes was responsible for increased SGA rates and a lower percentage of AGA fetuses (F₁ generation). The restricted female pups from severely diabetic dams presented rapid neonatal catch-up growth, glucose intolerance, and insulin resistance status before and during pregnancy. At term pregnancy of F₁ generation, oxidative stress status was observed in the maternal liver and blood samples. In addition, their offspring (F₂ generation) had lower fetal weight and placental efficiency, regardless of gender, which caused fetal growth restriction and confirmed the fetal programming influence.

Characterization of placental endocrine function and fetal brain development in a mouse model of small for gestational age

Conditions such as small for gestational age (SGA), which is defined as birthweight less than 10th percentile for gestational age can predispose to neurodevelopmental abnormalities compared to babies with normal birthweight. Fetal growth and birthweight depend on placental function, as this organ transports substrates to the developing fetus and it acts as a source of endocrine factors, including steroids and prolactins that are required for fetal development and pregnancy maintenance. To advance our knowledge on the aetiology of fetal growth disorders, the vast majority of the research has been focused on studying the transport function of the placenta, leaving practically unexplored the contribution of placental hormones in the regulation of fetal growth. Here, using mice and natural variability in fetal growth within the litter, we compared fetuses that fell on or below the 10th percentile (classified as SGA) with those that had adequate weight for their gestational age (AGA). In particular, we compared placental endocrine metabolism and hormone production, as well as fetal brain weight and expression of developmental, growth and metabolic genes between SGA and AGA fetuses. We found that compared to AGA fetuses, SGA fetuses had lower placental efficiency and reduced capacity for placental production of hormones (e.g. steroidogenic gene Cyp17a1, prolactin Prl3a1, and pregnancy-specific glycoproteins Psg21). Brain weight was reduced in SGA fetuses, although this was proportional to the reduction in overall fetal size. The expression of glucose transporter 3 (Slc2a3) was reduced despite the abundance of AKT, FOXO and ERK proteins were similar. Developmental (Sv2b and Gabrg1) and microglia genes (Ier3), as well as the pregnancy-specific glycoprotein receptor (Cd9) were lower in the brain of SGA versus AGA fetuses. In this mouse model of SGA, our results therefore demonstrate that placental endocrine dysfunction is associated with changes in fetal growth and fetal brain development.

Developmental Ultrasound Characteristics in Guinea Pigs: Similarities with Human Pregnancy

BACKGROUND

Biometrical and blood flow examinations are fundamental for assessing fetoplacental development during pregnancy. Guinea pigs have been proposed as a good model to study fetal development and related gestational complications; however, longitudinal growth and blood flow changes in utero have not been properly described. This study aimed to describe fetal and placental growth and blood flow of the main intrauterine vascular beds across normal guinea pig pregnancy and to discuss the relevance of this data for human pregnancy.

METHODS

Pregnant guinea pigs were studied from day 25 of pregnancy until term (day ~70) by ultrasound and Doppler assessment. The results were compared to human data from the literature.

RESULTS

Measurements of biparietal diameter (BPD), cranial circumference (CC), abdominal circumference, and placental biometry, as well as pulsatility index determination of umbilical artery, middle cerebral artery (MCA), and cerebroplacental ratio (CPR), were feasible to determine across pregnancy, and they could be adjusted to linear or nonlinear functions. In addition, several of these parameters showed a high correlation coefficient and could be used to assess gestational age in guinea pigs. We further compared these data to ultrasound variables from human pregnancy with high similarities.

CONCLUSIONS

BPD and CC are the most reliable measurements to assess fetal growth in guinea pigs. Furthermore, this is the first report in which the MCA pulsatility index and CPR are described across guinea pig gestation. The guinea pig is a valuable model to assess fetal growth and blood flow distribution, variables that are comparable with human pregnancy.

Fetal Growth Restriction Impairs Lung Function and Neurodevelopment in an Early Preterm Rabbit Model

We previously reported the multi-system sequelae of fetal growth restriction, induced by placental underperfusion, in near-term born rabbits, in the immediate neonatal period and up to pre-adolescence. Herein, we describe the pulmonary and neurodevelopmental consequences of FGR in rabbits born preterm. We hypothesize that FGR has an additional detrimental effect on prematurity in both pulmonary function and neurodevelopment. FGR was induced at gestational day (GD) 25 by placental underperfusion, accomplished by partial uteroplacental vessel ligation in one uterine horn. Rabbits were delivered by cesarean section at GD 29, and placentas were harvested for histology. Neonates underwent neurobehavioral or pulmonary functional assessment at postnatal day 1, followed by brain or lung harvesting, respectively. The neurodevelopmental assessment included neurobehavioral testing and multiregional quantification of cell density and apoptosis in the brain. Lung assessment included functional testing, alveolar morphometry, and airway histology. FGR was associated with higher perinatal mortality, lower birth and placental weight, and a similar brain-to-body weight ratio compared to controls. Placental underperfusion decreased labyrinth and junction zone volumes in FGR placentas. FGR impaired pulmonary function, depicted by higher parenchymal resistance, damping, and elastance. Alveolar morphometry and airway smooth muscle content were comparable between groups. Neurobehavioral tests showed motoric and sensorial impairment in FGR rabbits. In FGR brains, cell density was globally reduced, with higher apoptosis in selected areas. In conclusion, in preterm-born rabbits, placental underperfusion leads to higher mortality, FGR, and impaired lung and brain development in early assessment. This study complements previous findings of placental, pulmonary, and neurodevelopmental impairment in near-term born rabbits in this model.

Reliability of Rodent and Rabbit Models in Preeclampsia Research

In vivo studies on the pathology of gestation, including preeclampsia, often use small mammals such as rabbits or rodents, i.e., mice, rats, hamsters, and guinea pigs. The key advantage of these animals is their short reproductive cycle; in addition, similar to humans, they also develop a haemochorial placenta and present a similar transformation of maternal spiral arteries. Interestingly, pregnant dams also demonstrate a similar reaction to inflammatory factors and placentally derived antiangiogenic factors, i.e., soluble fms-like tyrosine kinase 1 (sFlt-1) or soluble endoglin-1 (sEng), as preeclamptic women: all animals present an increase in blood pressure and usually proteinuria. These constitute the classical duet that allows for the recognition of preeclampsia. However, the time of initiation of maternal vessel remodelling and the depth of trophoblast invasion differs between rabbits, rodents, and humans. Unfortunately, at present, no known animal replicates a human pregnancy exactly, and hence, the use of rabbit and rodent models is restricted to the investigation of individual aspects of human gestation only. This article compares the process of placentation in rodents, rabbits, and humans, which should be considered when planning experiments on preeclampsia; these aspects might determine the success, or failure, of the study. The report also reviews the rodent and rabbit models used to investigate certain aspects of the pathomechanism of human preeclampsia, especially those related to incorrect trophoblast invasion, placental hypoxia, inflammation, or maternal endothelial dysfunction.

Placental vascular alterations are associated with early neurodevelopmental and pulmonary impairment in the rabbit fetal growth restriction model

Fetal growth restriction is one of the leading causes of perinatal mortality and morbidity and has consequences that extend well beyond the neonatal period. Current management relies on timely delivery rather than improving placental function. Several prenatal strategies have failed to show benefit in clinical trials after promising results in animal models. Most of these animal models have important developmental and structural differences compared to the human and/or are insufficiently characterized. We aimed to describe placental function and structure in an FGR rabbit model, and to characterize the early brain and lung developmental morbidity using a multimodal approach. FGR was induced in time-mated rabbits at gestational day 25 by partial uteroplacental vessel ligation in one horn. Umbilical artery Doppler was measured before caesarean delivery at gestational day 30, and placentas were harvested for computed microtomography and histology. Neonates underwent neurobehavioral or pulmonary functional assessment the day after delivery, followed by brain or lung harvesting, respectively. Neuropathological assessment included multiregional quantification of neuron density, apoptosis, astrogliosis, cellular proliferation, and oligodendrocyte progenitors. Brain region volumes and diffusion metrics were obtained from ex-vivo brain magnetic resonance imaging. Lung assessment included biomechanical tests and pulmonary histology. Fetal growth restriction was associated with labyrinth alterations in the placenta, driven by fetal capillary reduction, and overall reduced vessels volume. FGR caused altered neurobehavior paralleled by regional neuropathological deficits and reduced fractional anisotropy in the cortex, white matter, and hippocampus. In addition, FGR kittens presented functional alterations in the peripheral lung and structurally underdeveloped alveoli. In conclusion, in a uteroplacental insufficiency FGR rabbit model, placental vascular alterations coincide with neurodevelopmental and pulmonary disruption.

Hyperactivation of Wnt/β-catenin and Jak/Stat3 pathways in human and zebrafish foetal growth restriction models: Implications for pharmacological rescue

Foetal Growth Restriction (FGR), previously known as Intrauterine Growth Restriction (IUGR), is an obstetrical condition due to placental insufficiency, affecting yearly about 30 million newborns worldwide. In this work, we aimed to identify and pharmacologically target signalling pathways specifically involved in the FGR condition, focusing on FGR-related cardiovascular phenotypes. The transcriptional profile of human umbilical cords from FGR and control cases was compared with the response to hypoxia of zebrafish (Danio rerio) transgenic lines reporting in vivo the activity of twelve signalling pathways involved in embryonic development. Wnt/β-catenin and Jak/Stat3 were found as key pathways significantly dysregulated in both human and zebrafish samples. This information was used in a chemical-genetic analysis to test drugs targeting Wnt/β-catenin and Jak/Stat3 pathways to rescue a set of FGR phenotypes, including growth restriction and cardiovascular modifications. Treatments with the Wnt/β-catenin agonist SB216763 successfully rescued body dimensions, cardiac shape, and vessel organization in zebrafish FGR models. Our data support the Wnt/β-catenin pathway as a key FGR marker and a promising target for pharmacological intervention in the FGR condition.

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.

Diet-induced maternal obesity impacts feto-placental growth and induces sex-specific alterations in placental morphology, mitochondrial bioenergetics, dynamics, lipid metabolism and oxidative stress in mice

AIM

The current study investigated the impact of maternal obesity on placental phenotype in relation to fetal growth and sex.

METHODS

Female C57BL6/J mice were fed either a diet high in fat and sugar or a standard chow diet, for 6 weeks prior to, and during, pregnancy. At day 19 of gestation, placental morphology and mitochondrial respiration and dynamics were assessed using high-resolution respirometry, stereology, and molecular analyses.

RESULTS

Diet-induced maternal obesity increased the rate of small for gestational age fetuses in both sexes, and increased blood glucose concentrations in offspring. Placental weight, surface area, and maternal blood spaces were decreased in both sexes, with reductions in placental trophoblast volume, oxygen diffusing capacity, and an increased barrier to transfer in males only. Despite these morphological changes, placental mitochondrial respiration was unaffected by maternal obesity, although the influence of fetal sex on placental respiratory capacity varied between dietary groups. Moreover, in males, but not females, maternal obesity increased mitochondrial complexes (II and ATP synthase) and fission protein DRP1 abundance. It also reduced phosphorylated AMPK and capacity for lipid synthesis, while increasing indices of oxidative stress, specifically in males. In females only, placental mitochondrial biogenesis and capacity for lipid synthesis, were both enhanced. The abundance of uncoupling protein-2 was decreased by maternal obesity in both fetal sexes.

CONCLUSION

Maternal obesity exerts sex-dependent changes in placental phenotype in association with alterations in fetal growth and substrate supply. These findings may inform the design of personalized lifestyle interventions or therapies for obese pregnant women.

Brain outcomes in runted piglets: a translational model of fetal growth restriction

etal growth restriction (FGR) is associated with long-term neurodevelopmental disabilities including learning and behavioural disorders, autism, and cerebral palsy. Persistent changes in brain structure and function that are associated with developmental disabilities are demonstrated in FGR neonates. However, the mechanisms underlying these changes remain to be determined. There are currently no therapeutic interventions available to protect the FGR newborn brain. With the wide range of long-term neurodevelopmental disorders associated with FGR, the use of an animal model appropriate to investigating mechanisms of injury in the FGR newborn is crucial for the development of effective and targeted therapies for babies. Piglets are ideal animals to explore how perinatal insults affect brain structure and function. FGR occurs spontaneously in the piglet, unlike other animal models that require surgical or chemical intervention, allowing brain outcomes to be studied without the confounding impacts of experimental interventions. The FGR piglet mimics many of the human pathophysiological outcomes associated with FGR including asymmetrical growth restriction with brain sparing. This review will discuss the similarities observed in brain outcomes between the human FGR and FGR piglet from a magnetic resonance imaging in the living and a histological perspective. FGR piglet studies provide the opportunity to determine and track mechanisms of brain injury in a clinically relevant animal model of FGR. Findings from these FGR piglet studies may provide critical information to rapidly translate neuroprotective interventions to clinic to improve outcomes for newborn babies.

Importance of Windows of Exposure to Maternal High-Fat Diet and Feto-Placental Effects: Discrimination Between Pre-conception and Gestational Periods in a Rabbit Model

Context and Aim: Lipid overnutrition in female rabbits, from prepuberty, leads to impaired metabolism (dyslipidemia and increased adiposity) and follicular atresia, and, when continued during gestation, affects offspring phenotype with intrauterine growth retardation (IUGR) and leads to placental and lipid metabolism abnormalities. Growth retardation is already observed in embryo stage, indicating a possible implication of periconceptional exposure. The objective of this study was to discriminate the effects of preconception and gestational exposures on feto-placental development.

Materials and Methods: Rabbit 1-day zygotes were collected from female donors under control (CD) or high-fat-high-cholesterol (HD) diet and surgically transferred to the left and right uterus, respectively, of each H (n = 6) or C (n = 7) synchronized recipients. Close to term, four combinations, CC (n = 10), CH (n = 13), HC (n = 13), and HH (n = 6), of feto-placental units were collected, for biometry analyses. Fatty acid (FA) profiles were determined in placental labyrinth, decidua, fetal plasma, and fetal liver by gas chromatography and explored further by principal component analysis (PCA). Candidate gene expression was also analyzed by RT-qPCR in the placenta and fetal liver. Data were analyzed by Kruskal–Wallis followed by Dunn’s pairwise comparison test. Combinations of different data sets were combined and explored by multifactorial analysis (MFA).

Results: Compared to controls, HH fetuses were hypotrophic with reduced placental efficiency and altered organogenesis, CH presented heavier placenta but less efficient, whereas HC presented a normal biometry. However, the MFA resulted in a good separation of the four groups, discriminating the effects of each period of exposure. HD during gestation led to reduced gene expression (nutrient transport and metabolism) and big changes in FA profiles in both tissues with increased membrane linoleic acid, lipid storage, and polyunsaturated-to-saturated FA ratios. Pre-conception exposure had a major effect on fetal biometry and organogenesis in HH, with specific changes in FA profiles (increased MUFAs and decreased LCPUFAs).

Conclusion: Embryo origin left traces in end-gestation feto-placental unit; however, maternal diet during gestation played a major role, either negative (HD) or positive (control). Thus, an H embryo developed favorably when transferred to a C recipient (HC) with normal biometry at term, despite disturbed and altered FA profiles.

Hypoxic effects on the mitochondrial content and functions of the placenta in fetal growth restriction

INTRODUCTION

In this study we examined the hypothesis that a hypoxic intrauterine environment causes mitochondrial dysfunction of trophoblasts in fetal growth restriction (FGR).

METHODS

The mtDNA content, mRNA levels of mitochondrial encoded genes (ND6, COX I), mitochondrial membrane proteins (COX I, COX IV and VDAC), HIF-1α and BINP3 (mitophagy receptor) protein levels were examined in FGR placentas and normal placentas. The mitochondrial function (ATP production and mitochondrial membrane potential-ΔΨm) and above related proteins were further examined in hypoxic HTR-8/SVneo cells induced by cobalt chloride (CoCl2). Mitophagy and its regulating mechanism under hypoxia in FGR was also investigated.

RESULTS

Compared with normal controls, both FGR placentas and CoCl2-treated trophoblast cells demonstrated statistically lower mtDNA content, reduced mRNAs of mitochondrial encoding genes, and decreased mitochondrial membrane proteins, accompanied by increased HIF-1α. Mitochondrial functions were impaired as demonstrated by decreased ATP production, and, reduced ΔΨm in CoCl2-treated cells. Meanwhile, mitophagy was markedly enhanced as indicated by increased LC3 fluorescent puncta in mitochondria of hypoxic trophoblastic cells. The upregulated BINP3 expression was demonstrated in FGR placentas as well as in hypoxic trophoblastic cells.

DISCUSSION

We demonstrated that hypoxic conditions lead to impaired mitochondrial function in trophoblasts in FGR. Reduced mtDNA may be associated with enhanced mitophagy via activating HIF-1α/BINP3 signalling pathway, that may, in turn, affect nutrition and energy transfer to the growth-restricted fetus.

Non-human Primate Models to Investigate Mechanisms of Infection-Associated Fetal and Pediatric Injury, Teratogenesis and Stillbirth

A wide array of pathogens has the potential to injure the fetus and induce teratogenesis, the process by which mutations in fetal somatic cells lead to congenital malformations. Rubella virus was the first infectious disease to be linked to congenital malformations due to an infection in pregnancy, which can include congenital cataracts, microcephaly, hearing impairment and congenital heart disease. Currently, human cytomegalovirus (HCMV) is the leading infectious cause of congenital malformations globally, affecting 1 in every 200 infants. However, our knowledge of teratogenic viruses and pathogens is far from complete. New emerging infectious diseases may induce teratogenesis, similar to Zika virus (ZIKV) that caused a global pandemic in 2016-2017; thousands of neonates were born with congenital microcephaly due to ZIKV exposure in utero, which also included a spectrum of injuries to the brain, eyes and spinal cord. In addition to congenital anomalies, permanent injury to fetal and neonatal organs, preterm birth, stillbirth and spontaneous abortion are known consequences of a broader group of infectious diseases including group B streptococcus (GBS), Listeria monocytogenes, Influenza A virus (IAV), and Human Immunodeficiency Virus (HIV). Animal models are crucial for determining the mechanism of how these various infectious diseases induce teratogenesis or organ injury, as well as testing novel therapeutics for fetal or neonatal protection. Other mammalian models differ in many respects from human pregnancy including placentation, labor physiology, reproductive tract anatomy, timeline of fetal development and reproductive toxicology. In contrast, non-human primates (NHP) most closely resemble human pregnancy and exhibit key similarities that make them ideal for research to discover the mechanisms of injury and for testing vaccines and therapeutics to prevent teratogenesis, fetal and neonatal injury and adverse pregnancy outcomes (e.g., stillbirth or spontaneous abortion). In this review, we emphasize key contributions of the NHP model pre-clinical research for ZIKV, HCMV, HIV, IAV, L. monocytogenes, Ureaplasma species, and GBS. This work represents the foundation for development and testing of preventative and therapeutic strategies to inhibit infectious injury of human fetuses and neonates.

Strategies for intra-amniotic administration of fetal therapy in a rabbit model of intrauterine growth restriction

Intrauterine growth restriction affects up to 10% of all pregnancies, leading to fetal programming with detrimental consequences for lifelong health. However, no therapeutic strategies have so far been effective to ameliorate these consequences. Our previous study has demonstrated that a single dose of nutrients administered into the amniotic cavity, bypassing the often dysfunctional placenta via intra-amniotic administration, improved survival at birth but not birthweight in an intrauterine growth restriction rabbit model. The aim of this study was to further develop an effective strategy for intra-amniotic fetal therapy in an animal model. Intrauterine growth restriction was induced by selective ligation of uteroplacental vessels on one uterine horn of pregnant rabbits at gestational day 25, and fetuses were delivered by cesarean section on GD30. During the five days of intrauterine growth restriction development, three different methods of intra-amniotic administration were used: continuous intra-amniotic infusion by osmotic pump, multiple intra-amniotic injections, and single fetal intraperitoneal injection. Technical feasibility, capability to systematically reach the fetus, and survival and birthweight of the derived offspring were evaluated for each technique. Continuous intra-amniotic infusion by osmotic pump was not feasible owing to the high occurrence of catheter displacement and amnion rupture, while methods using two intra-amniotic injections and one fetal intraperitoneal injection were technically feasible but compromised fetal survival. Taking into account all the numerous factors affecting intra-amniotic fetal therapy in the intrauterine growth restriction rabbit model, we conclude that an optimal therapeutic strategy with low technical failure and positive fetal impact on both survival and birthweight still needs to be found.

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.

Ouabain Protects Nephrogenesis in Rats Experiencing Intrauterine Growth Restriction and Partially Restores Renal Function in Adulthood

Intrauterine growth restriction (IUGR) is, in general, accompanied by a reduction of the nephron number, which increases the risk of hypertension and renal dysfunction. Studies have revealed that ouabain can partially restore the number of nephrons during IUGR. However, there is limited information regarding the melioration of nephric structure and function. We used maternal malnutrition to induce an IUGR model in rats. Subsequently, we used a mini-pump to administer ouabain to IUGR rats during pregnancy. Male offspring were divided randomly into two groups. One group was fed a normal diet, whereas the other was fed an isocaloric 8% high-salt diet. Maternal malnutrition led to a reduction in the birth weight and number of nephrons in offspring. At the end of a 40-week follow-up period, offspring from the IUGR group had high blood pressure and abnormal excretion of urinary protein; these parameters were exacerbated in offspring fed a high-salt diet. However, ouabain administration during pregnancy could partially restore the number of nephrons in IUGR offspring, normalize blood pressure, and reduce urinary protein excretion, even when challenged with a high-salt diet. Pathology findings revealed that IUGR, particularly following feeding of a high-salt diet, damaged the ultrastructure of glomeruli, but these harmful effects were ameliorated in offspring treated with ouabain. Collectively, our data suggest that ouabain could rescue nephrogenesis in IUGR newborns and protect (at least in part) the structure and function of the kidney during adulthood even when encountering unfavorable environmental challenges in subsequent life.

Adaptations of the human placenta to hypoxia: opportunities for interventions in fetal growth restriction

BACKGROUND

The placenta is the functional interface between the mother and the fetus during pregnancy, and a critical determinant of fetal growth and life-long health. In the first trimester, it develops under a low-oxygen environment, which is essential for the conceptus who has little defense against reactive oxygen species produced during oxidative metabolism. However, failure of invasive trophoblasts to sufficiently remodel uterine arteries toward dilated vessels by the end of the first trimester can lead to reduced/intermittent blood flow, persistent hypoxia and oxidative stress in the placenta with consequences for fetal growth. Fetal growth restriction (FGR) is observed in ∼10% of pregnancies and is frequently seen in association with other pregnancy complications, such as preeclampsia (PE). FGR is one of the main challenges for obstetricians and pediatricians, as smaller fetuses have greater perinatal risks of morbidity and mortality and postnatal risks of neurodevelopmental and cardio-metabolic disorders.

OBJECTIVE AND RATIONALE

The aim of this review was to examine the importance of placental responses to changing oxygen environments during abnormal pregnancy in terms of cellular, molecular and functional changes in order to highlight new therapeutic pathways, and to pinpoint approaches aimed at enhancing oxygen supply and/or mitigating oxidative stress in the placenta as a mean of optimizing fetal growth.

SEARCH METHODS

An extensive online search of peer-reviewed articles using PubMed was performed with combinations of search terms including pregnancy, placenta, trophoblast, oxygen, hypoxia, high altitude, FGR and PE (last updated in May 2020).

OUTCOMES

Trophoblast differentiation and placental establishment are governed by oxygen availability/hypoxia in early pregnancy. The placental response to late gestational hypoxia includes changes in syncytialization, mitochondrial functions, endoplasmic reticulum stress, hormone production, nutrient handling and angiogenic factor secretion. The nature of these changes depends on the extent of hypoxia, with some responses appearing adaptive and others appearing detrimental to the placental support of fetal growth. Emerging approaches that aim to increase placental oxygen supply and/or reduce the impacts of excessive oxidative stress are promising for their potential to prevent/treat FGR.

WIDER IMPLICATIONS

There are many risks and challenges of intervening during pregnancy that must be considered. The establishment of human trophoblast stem cell lines and organoids will allow further mechanistic studies of the effects of hypoxia and may lead to advanced screening of drugs for use in pregnancies complicated by placental insufficiency/hypoxia. Since no treatments are currently available, a better understanding of placental adaptations to hypoxia would help to develop therapies or repurpose drugs to optimize placental function and fetal growth, with life-long benefits to human health.

Developmental programming of the female reproductive system-a review

Exposures to adverse conditions in utero can lead to permanent changes in the structure and function of key physiological systems in the developing fetus, increasing the risk of disease and premature aging in later postnatal life. When considering the systems that could be affected by an adverse gestational environment, the reproductive system of developing female offspring may be particularly important, as changes have the potential to alter both reproductive capacity of the first generation, as well as health of the second generation through changes in the oocyte. The aim of this review is to examine the impact of different adverse intrauterine conditions on the reproductive system of the female offspring. It focuses on the effects of exposure to maternal undernutrition, overnutrition/obesity, hypoxia, smoking, steroid excess, endocrine-disrupting chemicals, and pollutants during gestation and draws on data from human and animal studies to illuminate underlying mechanisms. The available data indeed indicate that adverse gestational environments alter the reproductive physiology of female offspring with consequences for future reproductive capacity. These alterations are mediated via programmed changes in the hypothalamic-pituitary-gonadal axis and the structure and function of reproductive tissues, particularly the ovaries. Reproductive programming may be observed as a change in the timing of puberty onset and menopause/reproductive decline, altered menstrual/estrous cycles, polycystic ovaries, and elevated risk of reproductive tissue cancers. These reproductive outcomes can affect the fertility and fecundity of the female offspring; however, further work is needed to better define the possible impact of these programmed changes on subsequent generations.

Molecular mechanisms governing offspring metabolic programming in rodent models of in utero stress

The results of different human epidemiological datasets provided the impetus to introduce the now commonly accepted theory coined as 'developmental programming', whereby the presence of a stressor during gestation predisposes the growing fetus to develop diseases, such as metabolic dysfunction in later postnatal life. However, in a clinical setting, human lifespan and inaccessibility to tissue for analysis are major limitations to study the molecular mechanisms governing developmental programming. Subsequently, studies using animal models have proved indispensable to the identification of key molecular pathways and epigenetic mechanisms that are dysregulated in metabolic organs of the fetus and adult programmed due to an adverse gestational environment. Rodents such as mice and rats are the most used experimental animals in the study of developmental programming. This review summarises the molecular pathways and epigenetic mechanisms influencing alterations in metabolic tissues of rodent offspring exposed to in utero stress and subsequently programmed for metabolic dysfunction. By comparing molecular mechanisms in a variety of rodent models of in utero stress, we hope to summarise common themes and pathways governing later metabolic dysfunction in the offspring whilst identifying reasons for incongruencies between models so to inform future work. With the continued use and refinement of such models of developmental programming, the scientific community may gain the knowledge required for the targeted treatment of metabolic diseases that have intrauterine origins.

Regulation of maternal-fetal metabolic communication

Pregnancy may be the most nutritionally sensitive stage in the life cycle, and improved metabolic health during gestation and early postnatal life can reduce the risk of chronic disease in adulthood. Successful pregnancy requires coordinated metabolic, hormonal, and immunological communication. In this review, maternal-fetal metabolic communication is defined as the bidirectional communication of nutritional status and metabolic demand by various modes including circulating metabolites, endocrine molecules, and other secreted factors. Emphasis is placed on metabolites as a means of maternal-fetal communication by synthesizing findings from studies in humans, non-human primates, domestic animals, rabbits, and rodents. In this review, fetal, placental, and maternal metabolic adaptations are discussed in turn. (1) Fetal macronutrient needs are summarized in terms of the physiological adaptations in place to ensure their proper allocation. (2) Placental metabolite transport and maternal physiological adaptations during gestation, including changes in energy budget, are also discussed. (3) Maternal nutrient limitation and metabolic disorders of pregnancy serve as case studies of the dynamic nature of maternal-fetal metabolic communication. The review concludes with a summary of recent research efforts to identify metabolites, endocrine molecules, and other secreted factors that mediate this communication, with particular emphasis on serum/plasma metabolomics in humans, non-human primates, and rodents. A better understanding of maternal-fetal metabolic communication in health and disease may reveal novel biomarkers and therapeutic targets for metabolic disorders of pregnancy.

State-of-the-Art and Prospective of Nanotechnologies for Smart Reproductive Management of Farm Animals

Many biotechnological assisted reproductive techniques (ART) are currently used to control the reproductive processes of farm animals. Nowadays, smart ART that considers technique efficiency, animal welfare, cost efficiency and environmental health are developed. Recently, the nanotechnology revolution has pervaded all scientific fields including the reproduction of farm animals, facilitating certain improvements in this field. Nanotechnology could be used to improve and overcome many technical obstacles that face different ART. For example, semen purification and semen preservation processes have been developed using different nanomaterials and techniques, to obtain semen doses with high sperm quality. Additionally, nanodrugs delivery could be applied to fabricate several sex hormones (steroids or gonadotrophins) used in the manipulation of the reproductive cycle. Nanofabricated hormones have new specific biological properties, increasing their bioavailability. Applying nanodrugs delivery techniques allow a reduction in hormone dose and improves hormone kinetics in animal body, because of protection from natural biological barriers (e.g., enzymatic degradation). Additionally, biodegradable nanomaterials could be used to fabricate hormone-loaded devices that are made from non-degradable materials, such as silicon and polyvinyl chloride-based matrixes, which negatively impact environmental health. This review discusses the role of nanotechnology in developing some ART outcomes applied in the livestock sector, meeting the concept of smart production.

Trophectoderm-Specific Knockdown of LIN28 Decreases Expression of Genes Necessary for Cell Proliferation and Reduces Elongation of Sheep Conceptus

LIN28 inhibits let-7 miRNA maturation which prevents cell differentiation and promotes proliferation. We hypothesized that the LIN28-let-7 axis regulates proliferation-associated genes in sheep trophectoderm in vivo. Day 9-hatched sheep blastocysts were incubated with lentiviral particles to deliver shRNA targeting LIN28 specifically to trophectoderm cells. At day 16, conceptus elongation was significantly reduced in LIN28A and LIN28B knockdowns. Let-7 miRNAs were significantly increased and IGF2BP1-3, HMGA1, ARID3B, and c-MYC were decreased in trophectoderm from knockdown conceptuses. Ovine trophoblast (OTR) cells derived from day 16 trophectoderm are a useful tool for in vitro experiments. Surprisingly, LIN28 was significantly reduced and let-7 miRNAs increased after only a few passages of OTR cells, suggesting these passaged cells represent a more differentiated phenotype. To create an OTR cell line more similar to day 16 trophectoderm we overexpressed LIN28A and LIN28B, which significantly decreased let-7 miRNAs and increased IGF2BP1-3, HMGA1, ARID3B, and c-MYC compared to control. This is the first study showing the role of the LIN28-let-7 axis in trophoblast proliferation and conceptus elongation in vivo. These results suggest that reduced LIN28 during early placental development can lead to reduced trophoblast proliferation and sheep conceptus elongation at a critical period for successful establishment of pregnancy.

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.