Trophoblast Volume Research Articles

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.

AimThe current study investigated the impact of maternal obesity on placental phenotype in relation to fetal growth and sex.MethodsFemale 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.ResultsDiet‐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.ConclusionMaternal 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.

Combining early (

Placental related adverse pregnancy outcomes such as fetal growth restriction have significant short- and long-term implications for both mother and fetus. This study aimed to determine if conventional and novel early first trimester ultrasound measures are associated with small for gestational age (SGA) neonates. In addition, we aimed to assess whether a combination of ultrasound measures, maternal characteristics and biochemistry improved the prediction of this adverse pregnancy outcome. This was a prospective cohort study including ultrasound measurements: trophoblast thickness (TT), trophoblast volume (TV), mean uterine artery pulsatility index, crown-rump length, fetal heart rate, mean sac diameter (MSD) and yolk sac diameter. Biochemical markers considered in the analysis were placental growth factor (PIGF), pregnancy - associated plasma protein A (PAPP-A), beta human chorionic gonadotropin and alpha fetoprotein. Regression models were fitted for ultrasound parameters using multiples of the median (MoM). All measures were compared with normal birthweight (BW) ≥10th centile and SGA (BW<10th centile). Logistic regression analysis was used to create a clinical prediction model for SGA based on maternal characteristics, ultrasound measurements at <11weeks gestational age and maternal biochemistry collected at 10-14weeks. As compared to pregnancies delivered of babies with normal BW (n=1068), MoM values for TT, TV, MSD, PAPP-A and PIGF were significantly reduced (P<0.05) in pregnancies delivered of SGA babies (n=73). The proposed logistic regression model includes maternal height, TV and PIGF resulting in an area under the receiver operator curve 0.70 (95% CI 0.63-0.76) for the prediction of SGA. A significantly decreased TV, measured <11weeks gestation, is predictive of BW<10th centile. With addition of maternal height and PIGF, this three-marker algorithm provided a reasonable predictive value for the development of SGA later in pregnancy.

First-trimester ultrasound features associated with subsequent miscarriage: A prospective study.

First-trimester miscarriage is common, with women increasingly offered an ultrasound scan early in the first trimester to assess the status of their pregnancy. Ultrasound is uniquely situated to significantly impact the clinical management of these women. This study aims to determine whether there were any differences in the early ultrasound appearances of pregnancies that continued to be viable or resulted in miscarriage before 12 weeks gestation. This was a prospective cohort study including ultrasound measurements: mean sac diameter (MSD), yolk sac diameter (YSD), crown-rump length (CRL), fetal heart rate (FHR), trophoblast thickness, trophoblast volume (TTV) and mean uterine artery pulsatility index (meanUAPI). Regression models were fitted for each parameter and Z-scores compared between cohorts that progressed or miscarried after the scan but before 12 weeks gestation. Logistic regression analysis was used to create a prediction model for miscarriage prior to 12 weeks gestation based on the standardised ultrasound measurements recorded during the early first-trimester scan. Comparison of Z-Scores for meanUAPI, TTV, FHR and MSD demonstrated significant variation between the two groups. The proposed logistic regression model resulted in an area under the receiver operator curve of 0.81. At a false-positive rate of 30%, the model resulted in a sensitivity of 76% (95% CI 64-89%). The combination of FHR, meanUAPI, TTV in a prediction model for miscarriage may prove to be of value for ongoing pregnancy management in the first trimester.

Progressive uterine artery occlusion in the Guinea pig leads to defects in placental structure that relate to fetal growth

Intrauterine growth restriction (IUGR) is a common obstetric complication with immediate and life-long consequences for offspring health. Yet the mechanisms underlying its aetiology require elucidation. Recent work in the guinea pig shows that progressive uterine artery occlusion induced IUGR and vascular dysfunction in pups. Here we explore the extent to which uterine artery occlusion influences fetal outcomes via impacts on placental morphology. Our study demonstrates that uterine artery occlusion severely compromised both the labyrinth exchange zone (increased fibrosis and reduced vascularisation, trophoblast volume, surface area and diffusing capacity) and interlobium zone (increased apoptosis), which likely contributed to the IUGR observed.

Sex differences in rat placental development: from pre-implantation to late gestation

BackgroundA male fetus is suggested to be more susceptible to in utero and birth complications. This may be due in part to altered morphology or function of the XY placenta. We hypothesised that sexual dimorphism begins at the blastocyst stage with sex differences in the progenitor trophectoderm (TE) and its derived trophoblast lineages, as these cells populate the majority of cell types within the placenta. We investigated sex-specific differences in cell allocation in the pre-implantation embryo and further characterised growth and gene expression of the placental compartments from the early stages of the definitive placenta through to late gestation.MethodsNaturally mated Sprague Dawley dams were used to collect blastocysts at embryonic day (E) 5 to characterise cell allocation; total, TE, and inner cell mass (ICM), and differentiation to downstream trophoblast cell types. Placental tissues were collected at E13, E15, and E20 to characterise volumes of placental compartments, and sex-specific gene expression profiles.ResultsPre-implantation embryos showed no sex differences in cell allocation (total, TE and ICM) or early trophoblast differentiation, assessed by outgrowth area, number and ploidy of trophoblasts and P-TGCs, and expression of markers of trophoblast stem cell state or differentiation. Whilst no changes in placental structures were found in the immature E13 placenta, the definitive E15 placenta from female fetuses had reduced labyrinthine volume, fetal and maternal blood space volume, as well as fetal blood space surface area, when compared to placentas from males. No differences between the sexes in labyrinth trophoblast volume or interhaemal membrane thickness were found. By E20 these sex-specific placental differences were no longer present, but female fetuses weighed less than their male counterparts. Coupled with expression profiles from E13 and E15 placental samples may suggest a developmental delay in placental differentiation.ConclusionsAlthough there were no overt differences in blastocyst cell number or early placental development, reduced growth of the female labyrinth in mid gestation is likely to contribute to lower fetal weight in females at E20. These data suggest sex differences in fetal growth trajectories are due at least in part, to differences in placenta growth.

How Does Tobacco Smoke Affect Fetal Growth Potential in the First Trimester of Pregnancy as Measured by Volume Parameters of the Fetus, Trophoblast, and Gestational Sac?

We aimed to assess if tobacco smoke, as measured by the serum concentration of cotinine and blood concentration of cadmium, influences the fetal, sac, and trophoblast volume in the first trimester of pregnancy. We enrolled women in weeks 11 to 14 of pregnancy: 35 smokers, 24 passive smokers, and 98 nonsmoking healthy women. We found that the fetus volume was similar in all groups (18.70 ± 6.29, 17.11 ± 5.4, 18.97 ± 7.55 cm3). The trophoblast was significantly smallest in smokers (50.27 ± 19.56, 56.71 ± 23.50, 61.95 ± 22.94 cm3). The trophoblast volume was correlated with cotinine and cadmium concentration ( r = -0.54, r = -0.44). In passive smokers, gestational sac and trophoblast volume grew systematically and were correlated with the mean parental height. In smokers, only the gestational sac grew systematically and was correlated with the mean parental height. The fetus volume was independent of mean parental height and intensity of exposure to tobacco smoke. Volumetric changes of the fetus, trophoblast, and sac may be observed in the first trimester; however, their consequences require further research.

Increased dietary protein in the second trimester of gestation increases live weight gain and carcass composition in weaner calves to 6 months of age

Genetically similar nulliparous Polled Hereford heifers from a closed pedigree herd were used to evaluate the effects of dietary protein during the first and second trimester of gestation upon foetal, placental and postnatal growth. Heifers were randomly allocated into two groups at 35 days after artificial insemination (35 days post conception (dpc)) to a single bull and fed high (15.7% CP) or low (5.9% CP) protein in the first trimester (T1). At 90 dpc, half of each nutritional treatment group changed to a high- or low-protein diet for the second trimester until 180 dpc (T2). High protein intake in the second trimester increased birth weight in females (P=0.05), but there was no effect of treatment upon birth weight when taken over both sexes. Biparietal diameter was significantly increased by high protein in the second trimester with the effect being greater in the female (P=0.02), but also significant overall (P=0.05). Placental weight was positively correlated with birth weight, fibroblast volume and relative blood vessel volume (P<0.05). Placental fibroblast density was increased and trophoblast volume decreased in the high-protein first trimester treatment group (P<0.05). There was a trend for placental weight to be increased by high protein in the second trimester (P=0.06). Calves from heifers fed the high-protein treatment in the second trimester weighed significantly more on all occasions preweaning (at 1 month (P=0.0004), 2 months (P=0.006), 3 months (P=0.002), 4 months (P=0.01), 5 months (P=0.03), 6 months (P=0.001)), and grew at a faster rate over the 6-month period. By 6 months of age, the calves from heifers fed high nutrition in the second trimester weighed 33 kg heavier than those fed the low diet in the second trimester. These results suggest that dietary protein in early pregnancy alters the development of the bovine placenta and calf growth to weaning.

67 MATERNAL OBESITY AT CONCEPTION AND INSULIN SENSITIVITY IN LATE GESTATION ALTERS PLACENTAL STRUCTURE BUT NOT FETAL BIOMETRY AT BIRTH IN THE HORSE

Obesity is a major health issue in the horse industry, often associated with insulin resistance. This study aimed to analyse effects of maternal obesity at insemination and insulin resistance during late gestation on term placenta and foals at term. A total of 24 multiparous saddlebred mares were allocated to 1 of 2 groups at insemination: group obese (O) had a body condition score (BCS, French scale 1–5) &gt;4 (N = 15), and group normal (N) had a BCS = 4 (N = 9). From insemination until the sixth month of gestation, all the mares had access to pasture. From wintering, they were housed in box stalls and fed the same amount of energy, proteins, and fibre as a percentage of their body weight. During all the gestation, BCS, basal blood glucose, insulin, triglycerides, and nonesterified fatty acid plasma concentrations were measured each month. At 300 days of gestation, a frequent sampling glucose tolerance test, enabling the simultaneous evaluation of insulin sensitivity (IS) and glucose tolerance, was performed. At birth, placentas and foals were measured. Placentas were sampled around the umbilical cord to perform structural and functional analyses by stereology and RT-qPCR. Results were analysed using a type 3 ANOVA taking into account mare group and foal sex. Effects were considered significant when P &lt; 0.05. At 300 days of gestation, the frequent sampling glucose tolerance test indicated that half of the O mares were insulin resistant (IS &lt;1; N = 8), whereas the other half were insulin sensitive (IS &gt;1; N = 7). Based on these results, O mares were subdivided in 2 groups: obese resistant and obese sensitive (OS). Obese resistant mares were 61% less insulin sensitive than N mares and 59% less insulin sensitive than OS mares (P &lt; 0.0001, P &lt; 0.01, respectively). There was no difference for IS between N and OS mares. All analyses were thus performed comparing the 3 groups. In the N group, 3 mares were insulin resistant (one-third of the mares of the N group). Feed intake during wintering was not different between groups. Mares of both O groups maintained a high BCS (&gt;4) during pregnancy, whereas N mares lost BCS down 2.75 at birth (&lt;0.001). Basal glucose, insulin, triglycerides, and nonesterified fatty acid plasma were not different during gestation. At birth, no difference was observed for placental weight, surface and volume, nor for foal weight and withers height. The volume of allantoic vessels was reduced in placentas of OS mares compared with those of OR (P = 0.03; 78%) and N mares (P = 0.005; 65%). Moreover, placentas from OS mares had an increased volume of haemotrophic trophoblast (P = 0.03) and microcotyledonary vessels (P = 0.03) compared with N mares. No difference of expression was observed for 11 genes related to nutrient transfer, vascularization, growth, and development. Mare that are obese at insemination and insulin sensitive in late gestation appear to develop placental structural adaptations during gestation, possibly to increase fetoplacental exchanges, compared with obese, insulin resistant mares and lean mares. The monitoring of foal development (growth, metabolism, and osteoarticular status) is ongoing.

Prostaglandin E2 inhibits the proinflammatory phenotype induced by TGF-β on monocyte-derived dendritic cells

Prostaglandin E2 inhibits the proinflammatory phenotype induced by TGF-β on monocyte-derived dendritic cells

Analysis of placental vascularization in a pharmacological rabbit model of IUGR induced by l-NAME, a nitric oxide synthase inhibitor

ObjectivesWe have previously validated the use of l-nitro-arginine methyl ester (l-NAME), a nitric oxide synthase inhibitor, to induce placental hypoperfusion in a rabbit model. Here, the effects of l-NAME on placental vascularization were explored. Transplacental transfer of l-NAME and/or its active metabolite, NG-nitro-l-arginine (L-NOARG), was evaluated. Methods25 pregnant female rabbits were allocated on day 24 to one of 5 groups: l-NAME groups (31.35, 62.5, 125 and 250 mg/kg/day) or Control group (C). On Day 28, the labyrinthine area was analyzed for stereology and gene expression. l-NAME and L-NOARG were quantified in maternal and fetal blood. ResultsThe volume density of fetal vessels was significantly decreased in l-NAME (including 62.5–250 mg/kg/day which induced an IUGR) compared to C groups. l-NAME induced an increase of the volume and surface density of the maternal blood space. The trophoblast volume density remained unchanged as well as the surface density of fetal vessels. Relative expression of eNOS, VEGFA, VEGFR-1 and VEGFR-2 in placentas was not affected by 125 mg/kg/day l-NAME treatment, whereas IGF-2 expression was significantly increased in this l-NAME group compared to C. l-NAME was not detected in maternal nor fetal plasma. In contrast, fetal to maternal L-NOARG ratio was 100% in all l-NAME groups. ConclusionThese data demonstrate that l-NAME induced placental hypovascularization. The active L-NOARG metabolite is found in maternal and fetal plasma at similar concentrations. This could impact the fetal growth and reduces the interest of this model to study fetal outcomes of placental hypoperfusion.

Frozen Embryo Transfers Following Trophectoderm Biopsy Result in Lower Initial hCG Levels, But Result in High Pregnancy Rates and Normal Pregnancy Outcomes

Initial human chorionic gonadotropin (iHCG) levels are routinely used to counsel patients regarding likelihood of pregnancy.1 Low iHCG levels indicate high risk of early pregnancy loss. Trophectoderm (TE) biopsy for aneuploidy screening is being increasingly utilized to improve pregnancy rates. Given that TE biopsies necessarily reduce the trophoblast volume, this procedure might decrease iHCG levels and ultimately placental function. This study examined whether TE biopsy altered iHCG levels, their predictive values, and birth outcomes in frozen transfer cycles.

Early first-trimester trophoblast volume in pregnancies that result in live birth or miscarriage

To assess the validity of trophoblast volume measurements on three-dimensional ultrasound (3D-US) with Virtual Organ Computer-aided AnaLysis (VOCAL(TM) ), to create reference values between 6 and 12 weeks of gestation and to compare trophoblast volume between pregnancies ending in miscarriage and those resulting in live birth. In a prospective periconceptional cohort, we performed weekly 3D-US in 112 singleton pregnancies resulting in a non-malformed live birth and in 56 ending in miscarriage. Scans were performed between 6 and 12 weeks. Trophoblast volumes were calculated by subtracting the gestational sac volume from the volume of the total pregnancy. The interobserver and intraobserver agreement of measurements were determined to assess validity. Reference values were created for trophoblast volume in relation to crown-rump length and gestational age. A total of 722 3D-US examinations were available for offline VOCAL measurements, but measurements could be performed in only 53% of these due to non-targeted scanning and incomplete framing. Interobserver and intraobserver agreement for trophoblast volume measurements were excellent, with intraclass correlation coefficients > 0.97. Trophoblast volumes of pregnancies ending in miscarriage were significantly smaller (P < 0.01) than were those of pregnancies that resulted in live birth. Trophoblast growth in pregnancies ending in miscarriage was also reduced compared with that in pregnancies that resulted in live birth. VOCAL is a valid technique for measuring trophoblast volume during the early first trimester of pregnancy. Pregnancies ending in miscarriage have smaller trophoblast volumes as well as reduced trophoblast growth compared with those that result in live birth.

Miscarriage in contemporary maternal-fetal medicine: targeting clinical dilemmas

Miscarriage in contemporary maternal-fetal medicine: targeting clinical dilemmas

Trophectoderm (TE) biopsy for aneuploidy screening results in lower initial hCG levels with altered predictive values: low initial levels still have high delivery rates and normal pregnancy outcomes

Lower initial HCG (iHCG) levels 2 weeks after oocyte retrieval predict higher early pregnancy loss risk and may be used for counseling and to direct treatment. TE biopsy is becoming routine and given that it necessarily reduces initial trophoblast volume, it might alter iHCG levels and eventually placental sufficiency. This study seeks to determine whether TE biopsy impacts iHCG levels, their predictive value for delivery, and eventual newborn outcomes.

A quantitative analysis of transcriptionally active syncytiotrophoblast nuclei across human gestation

The syncytiotrophoblast (STB) epithelial covering of the human placenta is a unique terminally differentiated, multi-nucleated syncytium. No mitotic bodies are observed in the STB, which is sustained by continuous fusion of underlying cytotrophoblast cells (CTB). As a result, STB nuclei are of different ages. Morphologically, they display varying degrees of chromatin compaction, suggesting progressive maturational changes. Until recently, it was thought that STB nuclei were transcriptionally inactive, with all the mRNAs required by the syncytium being incorporated upon fusion of CTB. However, recent research has shown the presence of the active form of RNA polymerase II (RNA Pol II) in some STB nuclei. In this study, we confirm the presence of transcriptional activity in STB nuclei by demonstrating immunoreactivity for a transcription factor and an RNA polymerase I (RNA Pol I) co-factor, phospho-cAMP response element-binding protein and phospho-upstream binding factor, respectively. We also show, through immunoco-localisation studies, that a proportion of STB nuclei are both RNA Pol I and II transcriptionally active. Finally, we quantify the numerical densities of nuclei immunopositive and immunonegative for RNA Pol II in the STB of normal placentas of 11-39 weeks gestational age using an unbiased stereological counting tool, the physical disector. These data were combined with estimates of the volume of trophoblast to calculate total numbers of both types of nuclei at each gestational age. We found no correlation between gestational age and the numerical density of RNA Pol II-positive nuclei in the villous trophoblast (r = 0.39, P > 0.05). As the number of STB nuclei increases exponentially during gestation, we conclude that the number of transcriptionally active nuclei increases in proportion to trophoblast volume. The ratio of active to inactive nuclei remains constant at 3.9:1. These findings confirm that the majority of STB nuclei have intrinsic transcriptional activity, and that the STB is not dependent on CTB fusion for the provision of transcripts.

Placental-specific Igf2 deficiency alters developmental adaptations to undernutrition in mice.

The pattern of fetal growth is a major determinant of the subsequent health of the infant. We recently showed in undernourished (UN) mice that fetal growth is maintained until late pregnancy, despite reduced placental weight, through adaptive up-regulation of placental nutrient transfer. Here, we determine the role of the placental-specific transcript of IGF-II (Igf2P0), a major regulator of placental transport capacity in mice, in adapting placental phenotype to UN. We compared the morphological and functional responses of the wild-type (WT) and Igf2P0-deficient placenta in WT mice fed ad libitium or 80% of the ad libitium intake. We observed that deletion of Igf2P0 prevented up-regulation of amino acid transfer normally seen in UN WT placenta. This was associated with a reduction in the proportion of the placenta dedicated to nutrient transport, the labyrinthine zone, and its constituent volume of trophoblast in Igf2P0-deficient placentas exposed to UN on d 16 of pregnancy. Additionally, Igf2P0-deficient placentas failed to up-regulate their expression of the amino acid transporter gene, Slc38a2, and down-regulate phosphoinositide 3-kinase-protein kinase B signaling in response to nutrient restriction on d 19. Furthermore, deleting Igf2P0 altered maternal concentrations of hormones (insulin and corticosterone) and metabolites (glucose) in both nutritional states. Therefore, Igf2P0 plays important roles in adapting placental nutrient transfer capacity during UN, via actions directly on the placenta and/or indirectly through the mother.

Ontogeny of Placental Structural Development and Expression of the Renin–Angiotensin System and 11β-HSD 2 Genes in the Rabbit

Common pregnancy complications are associated with impaired placental development. This study aimed to characterise the ontogeny of structural correlates of rabbit placental function, its expression of genes encoding components of the renin–angiotensin system (RAS), as well as 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD 2) mRNA since these are known to be expressed by the placenta and are associated with pregnancy complications, including preeclampsia and intrauterine programming. Placentae were collected at gestational age (GA) 14, 21 and 28 (term = 32 days). Gene expression was analysed using real time PCR and placental structures were quantified via image analyses. The volume densities and volumes of trophoblast, fetal capillaries, maternal blood space, surface density and surface area of trophoblast all progressively increased, while the arithmetic mean barrier thickness of trophoblast decreased across gestation. Maternal plasma renin activity (PRA) was positively correlated with volumes of trophoblast and maternal blood space, surface density and surface area of trophoblast. Placental renin mRNA declined (↓62%; P < 0.01) across gestation and was negatively correlated with maternal PRA (GA0), fetal and placental weights, placental angiotensin type 1 and 2 receptors (AT 1R and AT 2R) mRNA and volume of trophoblast. AT 1R mRNA expression was increased by 92% ( P < 0.001) across gestation. AT 2R mRNA expression was ∼81% ( P < 0.01) greater at GA14 compared to GA21. Placental 11β-HSD 2 mRNA expression was ∼74% greater ( P < 0.01) at GA21 than GA14, but by GA28 was similar to that at GA14. These data show that changes in placental gene expression are associated with key events in placental and fetal development, indicating that the rabbit provides a good model for investigations of pregnancy perturbations that alter the RAS or programme the fetus.

Maternal Insulin-like Growth Factor-II Promotes Placental Functional Development Via the Type 2 IGF Receptor in the Guinea Pig

In guinea pigs, maternal insulin-like growth factor (IGF) infusion in early-pregnancy enhances placental transport near-term, increasing fetal growth and survival. The effects of IGF-II, but not IGF-I, appear due to enhanced placental labyrinthine (exchange) development. To determine if the type-2 IGF receptor (IGF2R) mediates these distinct actions of exogenous IGF-II in the mother, we compared the impact of IGF-II with an IGF-II analogue, Leu 27-IGF-II, which only binds the IGF2R. IGF-II, Leu 27-IGF-II (1 mg/kg per day.sc) or vehicle were infused from days 20–38 of pregnancy (term = 67 days) and placental structure and uptake and transfer of [ 3H]-methyl- d-glucose (MG) and [ 14C]-amino-isobutyric acid (AIB) and fetal growth and plasma metabolites, were measured on day 62. Both IGF-II and Leu 27-IGF-II increased the volume of placental labyrinth, trophoblast and maternal blood space within the labyrinth and total surface area of trophoblast for exchange, compared to vehicle. Leu 27-IGF-II also reduced the barrier to diffusion (trophoblast thickness) compared to vehicle and IGF-II. Both IGF-II and Leu 27-IGF-II increased fetal plasma amino acid concentrations and placental transfer of MG to the fetus compared to vehicle, with Leu 27-IGF-II also increasing AIB transport compared with vehicle and IGF-II. In addition, Leu 27-IGF-II increased fetal weight compared to vehicle. In conclusion, maternal treatment with IGF-II or Leu 27-IGF-II in early gestation, induce similar placental and fetal outcomes near term. This suggests that maternal IGF-II in early gestation acts in part via the IGF2R to persistently enhance placental functional development and nutrient delivery and promote fetal growth.

Somatic cell nuclear transfer in the sheep induces placental defects that likely precede fetal demise

The efficiency of cloning by somatic cell nuclear transfer (SCNT) is poor in livestock with approximately 5% of transferred cloned embryos developing to term. SCNT is associated with gross placental structural abnormalities. We aimed to identify defects in placental histology and gene expression in failing ovine cloned pregnancies to better understand why so many clones generated by SCNT die in utero. Placentomes from SCNT pregnancies (n = 9) and age matched, naturally mated controls (n = 20) were collected at two gestational age ranges (105-134 days and 135-154 days; term = 147 days). There was no effect of cloning on total placental weight. However, cloning reduced the number of placentomes at both gestational ages (105-134 days: control 55.0 +/- 4.2, clone 44.7 +/- 8.0 and 135-154 days: control 72.2 +/- 5.1, clone 36.6 +/- 5.1; P < 0.001) and increased the mean individual placentome weight (105-134 days: control 10.6 +/- 1.3 g, clone 18.6 +/- 2.8 g and 135-154 days: control 6.6 +/- 0.6 g, clone 7.0 +/- 2.0 g; P < 0.02). Placentomes from cloned pregnancies had a significant volume of shed trophoblast and fetal villous hemorrhage, absent in controls, at both gestational age ranges (P < 0.001) that was shown to be apoptotic by activated caspase-3 immunoreactivity. Consequently, the volume of intact trophoblast was reduced and the arithmetic mean barrier thickness of trophoblast through which exchange occurs was altered (P < 0.001) at both gestational age ranges in clones. In addition, cloning reduced placental expression of key genes in placental differentiation and function. Thus, cloning by SCNT results in both gross and microscopic placental abnormalities. We speculate that trophoblast apoptosis, shedding, and hemorrhage may be causal in fetal death in ovine clones.

Maternal Insulin-Like Growth Factors-I and -II Act via Different Pathways to Promote Fetal Growth

The placenta transports substrates and wastes between the maternal and fetal circulations. In mice, placental IGF-II is essential for normal placental development and function but, in other mammalian species, maternal circulating IGF-II is substantial and may contribute. Maternal circulating IGFs increase in early pregnancy, and early treatment of guinea pigs with either IGF-I or IGF-II increases placental and fetal weights by mid-gestation. We now show that these effects persist to enhance placental development and fetal growth and survival near term. Pregnant guinea pigs were infused with IGF-I, IGF-II (both 1 mg/kg.d), or vehicle sc from d 20-38 of pregnancy and killed on d 62 (term = 69 d). IGF-II, but not IGF-I, increased the mid-sagittal area and volume of placenta devoted to exchange by approximately 30%, the total volume of trophoblast and maternal blood spaces within the placental exchange region (+29% and +46%, respectively), and the total surface area of placenta for exchange by 39%. Both IGFs reduced resorptions, and IGF-II increased the number of viable fetuses by 26%. Both IGFs increased fetal weight by 11-17% and fetal circulating amino acid concentrations. IGF-I, but not IGF-II, reduced maternal adipose depot weights by approximately 30%. In conclusion, increased maternal IGF-II abundance in early pregnancy promotes fetal growth and viability near term by increasing placental structural and functional capacity, whereas IGF-I appears to divert nutrients from the mother to the conceptus. This suggests major and complementary roles in placental and fetal growth for increased circulating IGFs in early to mid-pregnancy.