Telomerase activity and apoptosis as indicators of ageing in placenta with and without intrauterine growth retardation

Disrupted Balance of the Oxidant-Antioxidant System in the Pathophysiology of Female Reproduction: Oxidative Stress and Adverse Pregnancy Outcomes

The significance of oxidative stress in the pathophysiology of male reproductive processes has been closely studied in the last two decades. Recently, it has become clear that oxidative stress can lead to numerous pathological conditions during female reproductive processes as well, contributing to the development of endometriosis, polycystic ovary syndrome and various forms of infertility. During pregnancy, physiological generation of reactive oxygen species (ROS) occurs in association with several developmental processes including oocyte maturation and implantation. An overproduction of ROS can lead to disturbances in fetal development and increases the risk for missed abortion, intrauterine growth restriction, pre-eclampsia, premature delivery and gestational diabetes. Our review focuses on the etiological role of the disrupted oxidant-antioxidant system during human gestation as it relates to adverse pregnancy outcomes.

Pathomechanisms of Prenatally Programmed Adult Diseases

Based on epidemiological observations Barker et al. put forward the hypothesis/concept that an adverse intrauterine environment (involving an insufficient nutrient supply, chronic hypoxia, stress, and toxic substances) is an important risk factor for the development of chronic diseases later in life. The fetus responds to the unfavorable environment with adaptive reactions, which ensure survival in the short run, but at the expense of initiating pathological processes leading to adult diseases. In this review, the major mechanisms (including telomere dysfunction, epigenetic modifications, and cardiovascular-renal-endocrine-metabolic reactions) will be outlined, with a particular emphasis on the role of oxidative stress in the fetal origin of adult diseases.

Evidence of Placental Aging in Late SGA, Fetal Growth Restriction and Stillbirth-A Systematic Review

During pregnancy, the placenta undergoes a natural aging process, which is considered normal. However, it has been hypothesized that an abnormally accelerated and premature aging of the placenta may contribute to placenta-related health issues. Placental senescence has been linked to several obstetric complications, including abnormal fetal growth, preeclampsia, preterm birth, and stillbirth, with stillbirth being the most challenging. A systematic search was conducted on Pubmed, Embase, and Scopus databases. Twenty-two full-text articles were identified for the final synthesis. Of these, 15 presented original research and 7 presented narrative reviews. There is a paucity of evidence in the literature on the role of placental aging in late small for gestational age (SGA), fetal growth restriction (FGR), and stillbirth. For future research, guidelines for both planning and reporting research must be implemented. The inclusion criteria should include clear differentiation between early and late SGA and FGR. As for stillbirths, only those with no other known cause of stillbirth should be included in the studies. This means excluding stillbirths due to congenital defects, infections, placental abruption, and maternal conditions affecting feto-maternal hemodynamics.

Educational Review: The Impact of Perinatal Oxidative Stress on the Developing Kidney

Oxidative stress occurs when there is an imbalance between reactive oxygen species/reactive nitrogen species and antioxidant systems. The interplay between these complex processes is crucial for normal pregnancy and fetal development; however, when oxidative stress predominates, pregnancy related complications and adverse fetal programming such as preterm birth ensues. Understanding how oxidative stress negatively impacts outcomes for the maternal-fetal dyad has allowed for the exploration of antioxidant therapies to prevent and/or mitigate disease progression. In the developing kidney, the negative impact of oxidative stress has also been noted as it relates to the development of hypertension and kidney injury mostly in animal models. Clinical research addressing the implications of oxidative stress in the developing kidney is less developed than that of the neurodevelopmental and respiratory conditions of preterm infants and other vulnerable neonatal groups. Efforts to study the oxidative stress pathway along the continuum of the perinatal period using a team science approach can help to understand the multi-organ dysfunction that the maternal-fetal dyad sustains and guide the investigation of antioxidant therapies to ameliorate the global toxicity. This educational review will provide a comprehensive and multidisciplinary perspective on the impact of oxidative stress during the perinatal period in the development of maternal and fetal/neonatal complications, and implications on developmental programming of accelerated aging and cardiovascular and renal disease for a lifetime.

Effect of Endogenic and Exogenic Oxidative Stress Triggers on Adverse Pregnancy Outcomes: Preeclampsia, Fetal Growth Restriction, Gestational Diabetes Mellitus and Preterm Birth

Oxidative stress is caused by an imbalance between the production of reactive oxygen species (ROS) in cells and tissues and the ability of a biological system to detoxify them. During a normal pregnancy, oxidative stress increases the normal systemic inflammatory response and is usually well-controlled by the balanced body mechanism of the detoxification of anti-oxidative products. However, pregnancy is also a condition in which this adaptation and balance can be easily disrupted. Excessive ROS is detrimental and associated with many pregnancy complications, such as preeclampsia (PE), fetal growth restriction (FGR), gestational diabetes mellitus (GDM), and preterm birth (PTB), by damaging placentation. The placenta is a tissue rich in mitochondria that produces the majority of ROS, so it is important to maintain normal placental function and properly develop its vascular network to ensure a safe and healthy pregnancy. Antioxidants may ameliorate these diseases, and related research is progressing. This review aimed to determine the association between oxidative stress and adverse pregnancy outcomes, especially PE, FGR, GDM, and PTB, and explore how to overcome this oxidative stress in these unfavorable conditions.

Telomere erosion as a placental clock: From placental pathologies to adverse pregnancy outcomes

The placenta provides nutritional and gas exchange between fetus and mother. Early in pregnancy, placental trophoblasts proliferate rapidly and invade aggressively. As pregnancy progresses, placental cells begin to age. Indeed, pregnancy itself has a tightly regulated duration, determined in large part by placental lifespan. Late in pregnancy, placental cells reach a senescent apoptotic state, activated by a number of intrinsic and extrinsic factors, including oxidative stress (OS), and DNA damage. Pregnancy complications, stillbirths and neonatal deaths have been related to OS and abnormal placental aging. Telomeres, the protective nucleoprotein structures at the ends of linear chromosomes, shorten both from cell replication and from exposure to OS. When telomeres become critically short they trigger cell cycle arrest and eventually cell death. Telomere attrition thus provide an intrinsic mechanism to explain tissue senescence and aging. Mounting evidence suggests that senescence of placental and fetal membrane cells results from telomere attrition. We review the studies that have addressed the role of telomere length (TL) in placentas from normal and complicated pregnancies, including pre-eclampsia, intrauterine growth restriction, gestational diabetes, and stillbirth. To date studies have uncovered associations between TL and a number of obstetrical complications. Future research is needed to determine whether these associations are causative, i.e. whether these clinical conditions result from telomere dysfunction, and whether particular features of telomeres, e.g. mean or shortest length, etc. could serve as clinically useful biomarkers of placental health.

Telomere Length and Telomerase Activity in Foetal Membranes from Term and Spontaneous Preterm Births

The reduction of telomere length, the protective cap structures of chromosomes, is one of the biomarkers of senescence (a mechanism of ageing), and ageing of foetal gestational tissues is associated with both term and preterm parturition. A mechanism regulating telomere length is the activity of telomerase, an enzyme that adds telomere fragments during DNA replication and cell division; however, its role in regulating telomere length is not well studied in gestational tissues. The objective of this study is to correlate telomere length and telomerase activity in foetal membranes from term and spontaneous preterm births. Foetal membrane samples were collected from pregnant women experiencing term labour (TL), term not in labour (TNL), preterm premature rupture of membranes (pPROM) and spontaneous preterm labour (PTL) with intact membranes (n = 20/group). Telomere length and telomerase activity were analyzed by relative quantification (T/S), real-time PCR and PCR-based fluorometric detection, respectively. Data were analyzed by ANOVA or the Kruskal-Wallis test. Demographic variables were not statistically different among the groups. Foetal membranes from the TL group showed telomere length reduction compared with those from the others (p < 0.0002). Telomerase activity did not change in foetal membranes irrespective of pregnancy outcome. Telomere shortening in foetal membranes is suggestive of senescence associated with triggering of labour at term; however, this is likely independent of telomerase activity, while prematurity may be associated with senescence, but due to other mechanisms than telomere length reduction in foetal membranes.

Adverse Birth Outcomes and Birth Telomere Length: A Systematic Review and Meta-Analysis

OBJECTIVES

To synthesize previous findings on the difference in birth telomere length between newborns with and without intrauterine growth restriction (IUGR) or with and without preterm birth.

STUDY DESIGN

We systematically searched 3 databases (PubMed, Embase, and Web of Science) for publications that examined the relationships of IUGR or preterm birth with birth telomere length. We conducted meta-analysis to pool the estimated difference in birth telomere length either between IUGR and non-IUGR or between preterm birth and full-term birth. Subgroup analyses were conducted by tissues (newborn blood vs placenta) and techniques used for telomere length measurement (quantitative polymerase chain reaction [qPCR] vs telomere restriction fragment).

RESULTS

We included 11 articles on comparing birth telomere length between IUGR (combined n = 227) and non-IUGR (n = 1897) and 7 articles on comparing birth telomere length between preterm birth (n = 182) and full-term birth (n = 1320). We found IUGR was associated with shorter birth telomere length only when birth telomere length was measured in placenta (pooled standardized mean difference [SMD] = -0.85; 95% CI -1.13 to -0.57; IUGR/non-IUGR n = 87/173), but not in newborn blood (pooled SMD = 0.00, 95% CI -0.18 to 0.19; IUGR/non-IUGR n = 148/1733). Birth telomere length was significantly longer in preterm birth than in full-term birth when birth telomere length was measured by qPCR (pooled SMD = 0.40, 95% CI 0.18-0.63; preterm birth/full-term birth n = 137/682) but not by telomere restriction fragment (pooled SMD = 0.05, 95% CI -0.29 to 0.38; preterm birth/full-term birth n = 44/444).

CONCLUSIONS

IUGR is associated with shorter placental telomere length and preterm birth is associated with longer birth telomere length measured by qPCR.

Is there a role for placental senescence in the genesis of obstetric complications and fetal growth restriction?

The placenta ages as pregnancy advances, yet its continued function is required for a successful pregnancy outcome. Placental aging is a physiological phenomenon; however, there are some placentas that show signs of aging earlier than others. Premature placental senescence and aging are implicated in a number of adverse pregnancy outcomes, including fetal growth restriction, preeclampsia, spontaneous preterm birth, and intrauterine fetal death. Here we discuss cellular senescence, a state of terminal proliferation arrest, and how senescence is regulated. We also explore the role of physiological placental senescence and how aberrant placental senescence alters placental function, contributing to the pathophysiology of fetal growth restriction, preeclampsia, spontaneous preterm labor/birth, and unexplained fetal death.

A role for cellular senescence in birth timing

Senescence contributes to the local and systemic aging of tissues and has been associated with age-related diseases. Recently, roles for this process during pregnancy have come to light, the dysregulation of which has been associated with adverse pregnancy outcomes such as preterm birth. Here, we summarize recent advances that support a role for senescence in birth timing and propose new aspects of study in this emerging field.

Oxidative stress, placental ageing-related pathologies and adverse pregnancy outcomes

Oxidative stress (OS), an imbalance between free radical generation and antioxidant defence, is recognized as a key factor in the pathogenesis of adverse pregnancy outcomes. Although OS is a common future of normal pregnancy, persistent, overwhelming OS leads to consumption and decline of antioxidants, affecting placental antioxidant capacity and reducing systems. The accumulation of OS causes damage to lipids, proteins and DNA in the placental tissue that induces a form of accelerated ageing. Premature ageing of the placenta is associated with placental insufficiency that prevents the organ meeting the needs of the foetus, and as a consequence, the viability of the foetus is compromised. This review summarizes the literature regarding the role of OS and premature placental ageing in the pathophysiology of pregnancy complications.

Telomerase activity in pregnancy complications (Review)

Telomeres are specific DNA regions positioned at the ends of chromosomes and composed of functional non-coding repeats. Upon cell division, the telomeres decrease in length by a preordained amount. When the telomeres become critically short, cells lose the ability to divide and enter a specific functioning mode designated as 'cellular senescence'. However, human tissues express an enzyme that deters the shrinking of the telomeres, the telomerase. Due to its ability to maintain telomere length, the telomerase slows down and possibly suspends the aging of the cells. In regard to this, solid evidence demonstrates that female human fertility decreases with increased maternal age and that various adverse factors, including alterations in telomerase activity, can contribute to age-associated infertility in women. The fact that telomerase activity is regulated in a time- and location-dependent manner in both embryo and placental tissues, highlights it potential importance to the successful completion of pregnancy. Since maternal age is a crucial determining factor for the success of in vitro and in vivo fertilization, numerous studies have focused on telomerase activity and its correlation with mammalian fertilization, as well as the following cleavage and pre-implantation developmental processes. Associations between telomerase activity and pregnancy complications have been previously observed. Our aim in this review was to summarize and critically discuss evidence correlating telomerase activity with pregnancy complications.

Placental aging and oxidation damage in a tissue micro-array model: an immunohistochemistry study

To evaluate the expression of markers correlated with cellular senescence and DNA damage (8-hydroxy-2'-deoxy-guanosine (8-OHdG), p53, p21, APE1/Ref-1 (APE1), interleukin (IL-6 and IL-8) in placentas from healthy and pathologic pregnancies. This retrospective study considered a placental tissue micro-array containing 92 controls from different gestational ages and 158 pathological cases including preeclampsia (PE), HELLP syndrome (hemolysis, elevated liver enzymes, low platelet count), small for gestational age (SGA) fetuses, and intrauterine growth restriction (IUGR) occurring at different gestational ages. In this study, we demonstrated a significant influence of gestational age on the expression in the trophoblast of 8-OHdG, p53, p21, APE1, and IL-6. In placentas of cases affected by PE, HELLP, or IUGR, there was an increased expression of 8-OHdG, p53, APE1, and IL-6 compared to controls (only IL-8 was significantly decreased in cases). In both groups of pathology between 22- and 34-week gestation and after 34-week gestation, APE1 levels were higher in the trophoblast of women affected by hypertensive disorders of pregnancy than women carrying an IUGR fetus. The cytoplasmic expression of 8-OHdG was increased in placentas in IUGR cases compared to PE or HELLP pregnancies. In cases after 34-week gestation, p21 was higher in SGA and IUGR than in controls and late PE. Moreover, p53 was increased after 34-week gestation in IUGR pregnancies. Placentas from pathological pregnancies had an altered expression of 8-OHdG, p53, p21, APE1, IL-6, and IL-8. The alterations of intracellular pathways involving these elements may be the cause or the consequence of placental dysfunction, but in any case reflect an impaired placental function, possibly due to increased aging velocity in pathologic cases.

Placental telomere length decreases with gestational age and is influenced by parity: a study of third trimester live-born twins

BACKGROUND

In contrast to the postnatal period, little is known about telomere length (TL) during prenatal life. The decrease in placental TL remains unknown, although intra uterine growth retardation and preeclampsia are associated with shorter placental TL. The aim of this study is to assess the decrease of placental TL during the third trimester of gestation and to explore the role of potential "growth influencing factors".

METHODS

The study sample consisted of 329 live-born twins from the East Flanders Prospective Twin Survey. TL was determined using a multiplex quantitative PCR method. Gestational age, sex, birth order, placental characteristics, parity, maternal and paternal age, diabetes, hypertension, smoking, alcohol use, and socio economic status (SES) were considered "growth influencing factors". Bivariable multilevel regression analysis with "growth influencing factors" was performed.

RESULTS

Placental TL ranged from 4.3 kbp to 84.4 kbp with a median of 10.8 kbp. Ln(TL) decreased in a linear fashion with an estimated TL decreasing from 13.98 kbp at 28 weeks to 10.56 kbp at 42 weeks. The regression coefficient of gestational age became smaller if considered together with SES (b = -0.017; p = 0.08) or diabetes (b = -0.018; p = 0.07) and bigger if considered together with parity (b = -0.022; p = 0.02), indicating that part of the association between gestational age and telomere length is explained by these three confounding factors.

CONCLUSION

Placental TL decreases during the third trimester of gestation of live-born twins with approximately 25% indicating that telomere shortening may play a role in aging of the placenta.

The long and short of it: the role of telomeres in fetal origins of adult disease

Placental insufficiency, maternal malnutrition, and other causes of intrauterine growth restriction (IUGR) can significantly affect short-term growth and long-term health. Following IUGR, there is an increased risk for cardiovascular disease and Type 2 Diabetes. The etiology of these diseases is beginning to be elucidated, and premature aging or cellular senescence through increased oxidative stress and DNA damage to telomeric ends may be initiators of these disease processes. This paper will explore the areas where telomere and telomerase biology can have significant effects on various tissues in the body in IUGR outcomes.

Reduced expression of survivin, the inhibitor of apoptosis protein correlates with severity of preeclampsia

INTRODUCTION

Preeclampsia is a major complication of pregnancy affecting maternal and fetal health. Although the pathogenesis of preeclampsia is unclear, it is believed that trophoblast apoptosis plays an important role in the pathogenesis of preeclampsia during pregnancy. Survivin is a member of the inhibitor of apoptosis protein family that uniquely promotes trophoblast proliferation. In this study we investigated the alteration of survivin levels during pregnancy and compared the survivin protein and mRNA between preeclampsia and normal pregnancy.

METHODS

The mRNA level of survivin in first, second and third trimester placentae was measured by Real-time PCR. The expression of survivin in preeclamptic placentae (including severe and mild preeclampsia) and in age-matched normal placentae was measured by immunohistochemistry. The mRNA levels of survivin in preeclamptic or normal placentae were measured by Real-time PCR.

RESULTS

The mRNA level of survivin was significantly reduced throughout gestation. The mRNA level of survivin in preeclamptic placentae was significantly reduced compared to that in normal placenta. The mRNA level of survivin in severe preeclamptic placentae was further significantly reduced compared to that in mild preeclamptic placentae. In addition, survivin was expressed on syncytiotrophoblasts and cytotrophoblasts and the expression of survivin was significantly decreased in preeclamptic placenta compared to that in normal placenta (p=0.01). Furthermore the expression of survivin in severe preeclamptic placentae was significantly lower than that in mild preeclamptic placentae.

CONCLUSION

Our current data suggests lower placental expression of survivin may be associated with the severity of preeclampsia.

Cord blood telomere length, telomerase activity and inflammatory markers in pregnancies in women with diabetes or gestational diabetes

AIMS

We tested the hypothesis that diabetes during pregnancy leads to chromosomal DNA damage and telomere attrition in the feto placental unit and cord blood, and provides evidence for intrauterine programming towards a senescent phenotype in the offspring.

METHODS

We obtained cord blood from pregnant women with pregestational Type 1 diabetes (n=26), Type 2 diabetes (n=20) or gestational diabetes (n=71), and control subjects without diabetes (n=45, n=76 and n=81, respectively) matched for maternal and gestational age. We measured cord blood mononuclear cell telomere length, telomerase activity (a reverse transcriptase that limits telomere attrition), and concentrations of insulin, high-sensitivity C-reactive protein (hs-CRP) and soluble intercellular adhesion molecule-1 (sICAM-1).

RESULTS

We found no significant differences between groups in cord blood telomere length in any nucleated cell type, or in hs-CRP or sICAM-1 concentrations, but telomerase activity was higher in cord blood from Type 1 (P<0.05) and gestational diabetes pregnancies (P<0.05), but not in Type 2 diabetes pregnancies. There were no significant relationships between glycaemic control, cord blood telomere length, telomerase activity or inflammatory markers in any group.

CONCLUSIONS

We found no difference in cord blood telomere length in pregnancies of women with diabetes compared with control subjects, but higher cord blood telomerase activity in Type 1 and gestational diabetes. This may reflect upregulated telomere reverse transcriptase in response to in utero oxidative DNA and telomere damage. These observations are relevant to the hypothesis that diabetes during pregnancy leads to in utero preprogramming towards senescence in the offspring.

eNOS, NO, and the activation of ERK and AKT signaling at mid-gestation and near-term in an ovine model of intrauterine growth restriction

Intrauterine growth restriction (IUGR) is a disease responsible for neonatal morbidity and mortality and perinatal death affecting 8% of all pregnancies. In sheep, IUGR that mimics the human IUGR disease closely can be brought on by environmental hyperthermia. Endothelial nitric oxidase synthase (eNOS) and nitric oxide (NO) are important in the regulation of blood flow in the fetal-placental circulation and are modulated by several factors including hypoxia. eNOS activity is also regulated by the phosphorylation of ERK1/2 and AKT proteins in various tissues. In a hyperthermic (HT) ovine model of IUGR with systemic hypertension and increased blood flow resistance, our objective was to determine the relationship between p-ERK, p-AKT, eNOS, and NO concentrations in the placenta, uterine, and umbilical vessels at mid-gestation and near-term. Eight pregnant ewes were exposed to hyperthermic conditions for either 55 or 80 days to induce IUGR. Sheep necropsies were performed at mid-gestation and near-term for collection of placentomes, umbilical vessels, and the uterine artery. Tissues were assessed for eNOS mRNA and protein, and p-ERK and p-AKT protein. Blood was collected for NO determination at the time of necropsy. Placental insufficiency and IUGR (PI-IUGR) pregnancies demonstrated: 1) reduced placental weight at mid-gestation and reduced placental and fetal weight near-term, 2) no changes in eNOS protein concentration in the uterine artery and umbilical vessels, but an increase in NO in umbilical vein blood at both time points, 3) no significant changes in signal transduction makers (ERK/AKT) in placental tissue at mid-gestation but a significant increase near-term in cotyledon tissues, and 4) an increase in p-AKT in the uterine vessels at term. The near-term findings of increased placental p-ERK and p-AKT proteins and umbilical vein NO concentration suggest one mechanism responsible for the increase in placental eNOS previously described in this PI-IUGR model characterized by fetal systemic hypertension and abnormal umbilical artery Doppler velocimetry.

The isolation and characterization of a novel telomerase immortalized first trimester trophoblast cell line, Swan 71

Studies using first trimester trophoblast cells may be limited by the inability to obtain patient samples and/or adequate cell numbers. First trimester trophoblast cell lines have been generated by SV40 transformation or similar methods, however, this approach is known to induce phenotypic and karyotypic abnormalities. The introduction of telomerase has been proposed to be a viable alternative for the immortalization of primary human cells. To investigate whether telomerase-induced immortalization might be a more feasible approach for the generation of first trimester trophoblast cell lines, we isolated primary trophoblast cells from a 7-week normal placenta and infected the cells with human telomerase reverse transcriptase (hTERT), the catalytic subunit of telomerase. Although this hTERT-infected first trimester trophoblast cell line, which we have named Swan 71, has been propagated for more than 100 passages, it still has attributes that are characteristic of primary first trimester trophoblast cells. The Swan 71 cells are positive for the expression of cytokeratin 7, vimentin and HLA-G, but do not express CD45, CD68 or the Fibroblast Specific Antigen (FSA), CD90/Thy-1. In addition, we also demonstrated that the Swan 71 cells secrete fetal fibronectin (FFN) as well as low levels of human Chorionic Gonadotrophin (hCG). Moreover, the Swan 71 cells exhibit a cytokine and growth factor profile that is similar to primary trophoblast cells and are resistant to Fas, but not TNF-alpha-induced apoptosis. This suggests that the Swan 71 cells may represent a valuable model for future in vitro trophoblast studies.

Absence of telomere shortening and oxidative DNA damage in the young adult offspring of women with pre-gestational type 1 diabetes

AIMS/HYPOTHESIS

The offspring of mothers with pre-gestational type 1 diabetes (PGDM) may be at increased risk of glucose intolerance and cardiovascular disease in childhood. The underlying causes of these observations, and whether they persist into adulthood, are unknown. The aim of the present study was to test the hypothesis that fetal chromosomal telomere oxidative DNA damage resulting from maternal PGDM programmes the offspring towards a senescent phenotype that is detectable in young adulthood.

METHODS

We studied 21 young adult offspring (age 16-23 years) with a maternal history of PGDM and 23 age- and weight-matched controls with no maternal history of diabetes. All participants underwent anthropometric assessments, a standard 75 g OGTT, measurement of peripheral blood mononuclear cell and skin fibroblast telomere length, fibroblast senescence, cell DNA damage (by determination of 8-oxoguanine levels using flow cytometry), plasma lipoprotein profiles (determined by nuclear magnetic resonance) and plasma levels of soluble adhesion molecules and inflammatory markers.

RESULTS

The groups did not differ significantly with respect to anthropometric measures, glucose tolerance, fasting and 2 h plasma insulin levels during OGTT, estimated peripheral insulin resistance, peripheral blood mononuclear cell or fibroblast telomere length, DNA damage or senescence in vitro, plasma NMR lipoprotein profiles or levels of high-sensitivity C-reactive protein. Plasma concentrations of soluble intercellular adhesion molecule 1 (sICAM-1; p < 0.05) and IL-6 (p = 0.08) were higher in the PGDM offspring.

CONCLUSIONS/INTERPRETATION

Young adult offspring of mothers with PGDM do not differ in terms of glucose tolerance, DNA damage or telomere length from controls of the same weight and BMI. This does not preclude such abnormalities at an earlier age, but there is no evidence of telomere damage as a pre-programming mechanism in the young adults enrolled in this study.

Telomerase and apoptosis in the placental trophoblasts of growth discordant twins

In an effort to investigate the molecular basis of growth discordance in embryos that experience the same uterine environment, we compared telomerase activity and apoptosis in placental trophoblasts obtained from growth discordant twins. Between January 2003 and February 2005, placental tissue from twenty pairs of twins was obtained within thirty minutes of delivery. Eleven cases were classified as growth discordant, with birth weight discordance greater than 20%. Nine cases comprised the control group, with less than 20% discordance. Telomerase and apoptotic activities in placental trophoblasts were analyzed by ELISA and immunoblot. Statistical significance was analyzed by a paired t-test, chi- squared test, and ANOVA (SPSS ver 11.0). The average growth discordance was 26.8% in the growth discordant group and 14.4% in the control group. There were no significant differences in maternal age, week of gestation at delivery, parity, or chorionisity between the two groups. In the growth discordant group, the larger twin showed significantly higher telomerase activity (p < 0.01), whereas no significant difference was observed in the control group (p = 0.36). In addition, there was no definitive correlation between telomerase activity and the degree of growth discordance in the larger or smaller twins (R = -0.521 and -0.399, p = 0.15 and 0.25, respectively). The apoptosis proteins Bax and Bcl 2 were detected in both the larger and smaller twins in the growth discordant and control groups. There was no statistically significant difference in Bax expression between the larger and smaller twins (p = 0.25 and 0.92, respectively) for either the growth discordant or the control groups. Bcl 2 expression also showed no significant difference between groups. In conclusion, a tendency toward reduced telomerase activity and increased apoptosis was discovered in placental trophoblasts of the smaller growth- discordant twin, possibility resulting in delayed fetal growh.

Chromosomal telomere attrition as a mechanism for the increased risk of epithelial cancers and senescent phenotypes in type 2 diabetes

Telomeres are the repeat DNA sequences at the end of chromosomes necessary for successful DNA replication and chromosomal integrity. Telomeres shorten at cell division at a rate determined by oxidative DNA damage, and cells are triggered into replicative senescence once telomeres shorten to a critical length. Telomere-related chromosomal maintenance also has a role in carcinogenesis. Type 2 diabetes is characterised by increased oxidative stress, increased oxidative DNA damage, senescent retinal and renal phenotypes, and an increased risk of epithelial malignancy. We suggest that increased oxidative DNA damage and telomere attrition in type 2 diabetes leads to: (1) carcinogenic telomere-dependent chromosomal non-reciprocal translocations, genomic instability, and the development of epithelial cancers; (2) senescent retinal and renal phenotypes (expressed as diabetic retinopathy and nephropathy); and (3) senescent vascular endothelial, monocyte-macrophage and vascular smooth muscle cells (expressed as endothelial dysfunction and accelerated atherogenesis). An adverse intrauterine environment leads to increased feto-placental oxidative stress and feto-placental oxidative DNA damage. We also suggest that intrauterine oxidative DNA damage and telomere shortening is another point at which increased oxidative stress could contribute to a pre-programmed increased risk of senescent phenotypes in adult offspring, characterised by type 2 diabetes and epithelial malignancy. These suggestions can be used to understand early glucose intolerance in the young children of type 1 diabetes pregnancies, poor cancer outcomes in type 2 diabetes, beta cell fatigue in type 2 diabetes and the absence of increased epithelial cancer risk in type 1 diabetes.

Long telomeres in the mature human placenta

OBJECTIVE

To investigate whether telomere shortening may play a role in senescence of the placenta.

STUDY DESIGN

Villous tissue was collected from single, random sites of full-term placentas (39-41 weeks of gestation; n=10) as well as multiple, specific sites of the same placenta (39-41 weeks of gestation; n=5). For the latter group of placentas, samples were taken near the umbilical cord and at the periphery on both the maternal and fetal sides (a total of 4 samples per placenta). Cord blood samples were also obtained from all placental donors. Telomerase activity was assessed by the TRAP assay, and telomere length measured by Southern analysis of mean terminal restriction fragment (TRF) length.

RESULTS

We show for the first time that telomeres are longer ( approximately 25% longer; P<0.001) in placenta tissue than in cord blood from the same donor.

CONCLUSION

Telomere shortening is unlikely to have a significant role in senescence or terminal maturation of the placenta.

Evaluation of the maternal and umbilical vein serum sFas/sFasL system in pregnancies complicated by preeclampsia with intrauterine growth retardation

OBJECTIVE

The aim of this study was to determine the maternal and umbilical vein soluble Fas and its ligand (sFasL) serum levels in pregnancies complicated by preeclampsia with intrauterine growth retardation (IUGR).

PATIENTS AND METHODS

The study was carried out on 11 preeclamptic delivering patients in the third trimester of pregnancy with severe preeclampsia complicated by intrauterine growth retardation. The control group consisted of 12 healthy normotensive delivering patients with singleton uncomplicated pregnancies, without any renal, heart and vascular diseases and with normal laboratory tests. Maternal and umbilical serum soluble Fas and FasL concentrations were estimated using a sandwich ELISA assay.

RESULTS AND CONCLUSIONS

Increased maternal and umbilical vein serum sFas and increased umbilical vein serum sFasL levels were found in the study group in comparison with the control group. In our study in both groups of patient higher maternal sFas values were observed in comparison with the umbilical cord blood. Further studies are necessary to evaluate the role of Fas/FasL pathway in pregnancies complicated by preeclampsia and intrauterine growth retardation.

Developmental indices of nutritionally induced placental growth restriction in the adolescent sheep

Most intrauterine growth restriction cases are associated with reduced placental growth. Overfeeding adolescent ewes undergoing singleton pregnancies restricts placental growth and reduces lamb birth weight. We used this sheep model of adolescent pregnancy to investigate whether placental growth restriction is associated with altered placental cell proliferation and/or apoptosis at d 81 of pregnancy, equivalent to the apex in placental growth. Adolescent ewes with singleton pregnancies were offered a high or moderate level of a complete diet designed to induce restricted or normal placental size at term, respectively. Bromodeoxyuridine (Brd-U) was administered to H and M ewes 1 h before slaughter. Placental tissues were examined for a) Brd-U (immunohistochemistry) and b) apoptosis regulatory genes by in situ hybridization, Northern analyses (bax, mcl-1), immunohistochemistry, and Western analyses (bax). Quantification was carried out by image analysis. Total placentome weights were equivalent between groups. Brd-U predominantly localized to the trophectoderm and was significantly lower in the H group. Bax and mcl-1 mRNA were localized to the maternal-fetal interface. Bax protein was significantly increased in the H group and predominant in the uninuclear fetal trophectoderm. These observations indicate that reduced placental size at term may be due to reduced placental cell proliferation and possibly increased apoptosis occurring much earlier in gestation.

Temporal and spatial patterns of expression of inhibitors of apoptosis in human placentas

The apoptosis cascade that plays a central role in normal and pathological processes is strictly controlled, in part by newly described members of the inhibitor of apoptosis (IAP) family (HIAP-1, HIAP-2, XIAP, NAIP, Survivin, and Livin). Here, we report the expression of IAP mRNAs and proteins in early and late gestation human placentas, term cytotrophoblast cells, and two choriocarcinoma cell lines, JEG-3 and Jar. Reverse transcriptase-polymerase chain reaction identified mRNAs derived from all of the currently known IAP genes in all samples. Analysis by immunoblotting revealed that IAP proteins are present in early and late gestation human placentas and that levels of IAPs are not identical in normal and transformed trophoblast cells. Immunohistochemical experiments performed on paraformaldehyde-fixed tissue sections taken from early and late stages of pregnancy demonstrated that expression patterns differed according to cell lineage and stage of cell differentiation. The results of this study are consistent with the postulate that IAP proteins have critical roles in placental cell survival and suggest that specific apoptosis inhibitors may protect normal and transformed trophoblast cells from cell death.

Placental apoptosis in discordant twins

OBJECTIVE

To investigate placental apoptosis in discordant dichorial twins.

METHODS

Placental samples were obtained from 7 third-trimester suitable twins. Discordancy was defined as a >25 per cent difference in newborn birth weight. Light microscopy using hematoxylin and eosin (H&E)-stained paraffin slides and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labelling (TUNEL) methods were used to confirm the incidence of apoptosis. Investigators were blinded to pregnancy outcome.

RESULTS

Both methods revealed that the incidence of apoptosis in the placentas of the smaller fetuses was significantly higher than in placentas of the larger fetuses. The incidence of TUNEL-positive cells in the former was 1.4+/-0.26 per cent: this was significantly higher than the incidence of apoptosis in the placental specimens of the latter (0.9+/-0.07 per cent, P< 0.02 Wilcoxon rank test). The same results were obtained with H&E: the incidence of apoptosis detected in placentas from the former was 1.07+/-0.1 per cent compared to 0.72+/-0.08 per cent in those of the latter (P< 0.02 Wilcoxon rank test).

CONCLUSIONS

Despite similar environment conditions, placental apoptosis is increased in the smaller fetus and thus might play a role in discordancy between twins. Since increased placental apoptosis has also been found in singleton intrauterine growth restriction, this supports the hypothesis that the smaller twin is selectively growth restricted.

Regulation of telomerase during human placental differentiation: a role for TGFbeta1

The transient tumor-like attributes of the first-trimester placenta anchor the developing embryo to the uterine wall thus establishing a vital link between the mother and the fetus. Dysregulation of this invasive behavior and/or controlled proliferation of the placenta is associated with abnormal pregnancies. Several of these diseased states also exhibit aberrant telomerase activity, among other pathophysiological manifestations. Considering the strong correlation between telomerase activity and tumorigenesis, it was of interest to see whether the crucial processes of trophoblast proliferation and differentiation were brought about through the modulation of telomerase. Using two in vitro model systems of trophoblast differentiation, we demonstrate here that telomerase activity is negatively regulated during placental differentiation. We further show that this modulation is at the level of transcription of hTERT. We also propose a role for TGF beta1 in regulating telomerase activity in differentiating trophoblasts by down-regulating the expression of hTERT at the transcriptional level.