Influence of Maternal Diabetes on Placental Fibroblast Growth Factor-2 Expression, Proliferation, and Apoptosis

Association of hyperglycaemia with the placenta of GDM-induced macrosomia with normal pre-pregnancy BMI and the proliferation of trophoblast cells

The aim of this study was to identify the effect of hyperglycaemia on placentas of gestational diabetes mellitus (GDM) women with macrosomia and normal pre-pregnancy body mass index (BMI), and uncover the molecular mechanism of hyperglycaemia on trophoblast cells in vitro. GDM women with normal pre-pregnancy BMI were divided into GM group (macrosomia, n = 30) and GN group (normal birth weight, n = 35). The study showed GM group had more adverse pregnancy outcomes and higher levels of gestational weight gain, blood glucose and triglyceride. After adjustment for confounding factors, just the fasting plasma glucose level and HbA1c percentage were related to the incidence of GDM-induced macrosomia with normal pre-pregnancy BMI. Meanwhile, the fasting blood glucose was closely related to the placental weight and placental PCNA expression. Furthermore, the in vitro model for placenta showed that hyperglycaemia significantly promoted trophoblast cell proliferation and activated ERK1/2 phosphorylation. ERK1/2 inhibitor markedly suppressed hyperglycaemia-induced trophoblastic proliferation. The fasting plasma glucose and placenta are closely related with the development of GDM-induced macrosomia with normal pre-pregnancy BMI. The mechanism may be hyperglycaemia promotes trophoblast cell proliferation via ERK1/2 signalling. It provides scientific evidence for optimising outcomes of GDM women with normal pre-pregnancy BMI.IMPACT STATEMENTWhat is already known on this subject? Gestational diabetes mellitus (GDM) is one of the strongest risk factors correlated with macrosomia. The hyperglycaemic intrauterine environment affects not only the foetus but also the placental development and function in humans and experimental rodents. However, placental abnormalities associated with maternal diabetes have been inconsistently reported, possibly because of population differences in pre-pregnancy weight, diabetes types, glycemic control or pregnancy complication, and the molecular mechanism of hyperglycaemia on trophoblast cells in vitro was not clearly stated.What do the results of this study add? This is the first study to identify the effect of hyperglycaemia on placentas of gestational diabetes mellitus (GDM) women with macrosomia and normal pre-pregnancy body mass index (BMI), and uncover the molecular mechanism of hyperglycaemia on trophoblast cells in vitro.What are the implications of these findings for clinical practice and/or further research? Understanding placental changes in the environment of abnormal glucose metabolism which can establish the maternal-placental-foetal interface dysfunction as a potential source of adverse pregnancy outcomes is very necessary. Our study found the fasting plasma glucose and placenta are closely related with the development of GDM-induced macrosomia with normal pre-pregnancy BMI. The mechanism may be hyperglycaemia promotes trophoblast cell proliferation via ERK1/2 signalling. It provides scientific evidence for optimising outcomes of GDM women with normal pre-pregnancy BMI, and could be used for the following studies of relationship between placenta and childhood complications.

Cell death mechanisms and their roles in pregnancy related disorders

Autophagy and apoptosis are catabolic pathways essential for homeostasis. They play a crucial role for normal placental and fetal development. These cell death mechanisms are exaggerated in placental disorders such as preeclampsia, intrauterine growth restriction (IUGR) and gestational diabetes mellitus (GDM). Apoptosis is widely studied, highly controlled and regulated whereas; autophagy is an orderly degradation and recycling of the cellular components. Cellular senescence may be initiated by a variety of stimuli, including hypoxia, oxidative stress, reduction in survival signals and nutrition deprivation. Apoptosis is regulated by two types of pathways intrinsic and extrinsic. Extrinsic pathway is initiated by apoptosis inducing cells such as macrophages, natural killer cells whereas; intrinsic pathway is initiated in response to DNA damage, cell injury and lack of oxygen. In autophagy, the cell or organelles undergo lysosomal degradation. Placental apoptosis increases as the gestation progresses while autophagy plays a role in trophoblast differentiation and invasion. In pregnancy disorders like preeclampsia and IUGR, proapoptotic markers such as caspase 3, 8, BAX are higher and antiapoptotic markers like Bcl-2 are lower. In GDM, apoptotic markers are reduced resulting in increased placental mass and fetal macrosomia. Apoptosis in the pathological pregnancies is also influenced by the reduced levels of micronutrients and long chain polyunsaturated fatty acids resulting in disturbed placental biology. This chapter describes the role of various key molecular events involved in cellular senescence and the various factors influencing them. This will help identify future therapeutic strategies for better management of these processes.

Placental Morphology and Cellular Characteristics in Stillbirths in Women With Diabetes and Unexplained Stillbirths

CONTEXT.—

Women with diabetes have increased stillbirth risk. Although the underlying pathophysiological processes are poorly understood, stillbirth is frequently related to abnormal placental structure and function.

OBJECTIVE.—

To investigate placental morphology and cellular characteristics in the placentas of women with diabetes who had stillbirths and stillbirths of unexplained cause.

DESIGN.—

Placentas from women with uncomplicated live births, live births in women with diabetes, unexplained stillbirths, and stillbirths related to diabetes (n = 10/group) underwent clinical histopathologic assessment and were also investigated using immunohistochemical staining to quantify syncytial nuclear aggregates, proliferation, trophoblast area, vascularization, T cells, placental macrophages (Hofbauer cells), and the receptor for advanced glycation end products.

RESULTS.—

Ki67+ cells were decreased in unexplained stillbirths compared with live births in women with diabetes. Both stillbirth groups had increased cytokeratin 7+/nuclear area compared with controls. Blood vessels/villi were decreased in unexplained stillbirth compared with live births from women with diabetes. Compared with uncomplicated controls, CD163+ macrophages were increased in live births in women with diabetes and unexplained stillbirths, and further increased in stillbirths related to diabetes. There was no change in CD3+ T cells or syncytial nuclear aggregates. Receptor for advanced glycation end products-positive cells were decreased in both stillbirth groups compared with diabetes-related live births. Co-localization of receptor for advanced glycation end products in macrophages was increased in both stillbirth groups compared with live birth groups.

CONCLUSIONS.—

Stillbirths related to diabetes exhibit placental phenotypic differences compared with live births. Further investigation of these parameters may provide understanding of the pathologic mechanisms of stillbirth and aid the development of stillbirth prevention strategies.

Sex hormone-binding globulin regulates the activity of the ERK pathway in the placentas of patients with gestational diabetes mellitus

The sex hormone-binding globulin (SHBG) is involved in the onset and progression of insulin resistance and metabolic syndromes, with its expression downregulated in the placental tissues of patients with gestational diabetes mellitus (GDM). However, the underlying mechanisms for these effects remain unclear. In this study, we enrolled an equal number (30) of GDM and non-GDM puerperae who underwent cesarean section at Shengjing Hospital. After due approval by the ethics committee, the expression levels of SHBG and extracellular-signal-regulated kinase (ERK) pathway markers in the placental tissues of these individuals were measured via reverse transcription-polymerase chain reaction (RT-PCR) and Western blot assays. The correlation analysis of these genes revealed that the expression of SHBG in placental tissues was downregulated and negatively correlated with the expression of ERK pathway markers, which were upregulated in placental tissues. Further investigations using the HTR-8/SVneo trophoblast cell line revealed that the trophoblasts with small interfering RNA (siRNA)-silenced SHBG expression displayed increased mRNA and protein expression levels of ERK pathway markers, as well as reduced apoptosis and enhanced proliferation. In contrast, trophoblasts with high SHBG expression showed a downregulated expression of ERK pathway markers, increased apoptosis, reduced proliferation, and a shorter S phase. Therefore, we believe that SHBG may participate in the onset of insulin resistance and GDM by regulating the activity of the ERK pathway.

Are there any relationships between umbilical artery Pulsatility Index and macrosomia in fetuses of type I diabetic mothers?

OBJECTIVE

To establish whether there are relationships between umbilical artery Pulsatility Index (PI) and fetal macrosomia in pregnancies complicated by type I diabetes.

METHODS

In a retrospective observational study, 102 singleton pregnant women with type I diabetes were considered. Umbilical artery PI was measured by Doppler ultrasonography within one week from delivery and related to neonatal weight. Pregnancies were grouped according to birtweight in macrosomic group (≥4000 g) and normal growth group (<4000 g). Relationships between umbilical artery PI and birth weight and birth weight centile were tested by Pearson's correlation analysis. Further umbilical artery PI values were compared between macrosomic and normally grown fetuses.

RESULTS

Birth weight was ≥4000 g in 24 pregnancies (23.5%). A significant relationship was found between umbilical artery PI and neonatal weight (r = 0.512; p < 0.01) and neonatal weight centile (r = 0.400; p < 0.01). Umbilical artery PI were significantly lower (t = -6.013; p < 0.001) in the macrosomic group (0.78; 95% confidence interval (CI) 0.73-0.84) than in the normal growth group (1.00; 95% CI 0.97-1.04).

CONCLUSIONS

In pregnancies complicated by type I diabetes there is a significant relationship between umbilical artery PI value before delivery and absolute birth weight and birth weight centile. Macrosomic fetuses show a significant reduction in umbilical artery PI when compared with diabetic pregnancies without fetal overgrowth.

Glucose, insulin, and oxygen interplay in placental hypervascularisation in diabetes mellitus

The placental vasculature rapidly expands during the course of pregnancy in order to sustain the growing needs of the fetus. Angiogenesis and vascular growth are stimulated and regulated by a variety of growth factors expressed in the placenta or present in the fetal circulation. Like in tumors, hypoxia is a major regulator of angiogenesis because of its ability to stimulate expression of various proangiogenic factors. Chronic fetal hypoxia is often found in pregnancies complicated by maternal diabetes as a result of fetal hyperglycaemia and hyperinsulinemia. Both are associated with altered levels of hormones, growth factors, and proinflammatory cytokines, which may act in a proangiogenic manner and, hence, affect placental angiogenesis and vascular development. Indeed, the placenta in diabetes is characterized by hypervascularisation, demonstrating high placental plasticity in response to diabetic metabolic derangements. This review describes the major regulators of placental angiogenesis and how the diabetic environment in utero alters their expression. In the light of hypervascularized diabetic placenta, the focus was placed on proangiogenic factors.

Reduced apoptosis in term placentas from gestational diabetic pregnancies

Gestational diabetic mellitus (GDM) pregnancies have an increased risk of macrosomic infants and large placental mass, though the mechanisms explaining each of these is uncertain. We sought to evaluate the contribution of apoptosis to placental size and the expression of glucose transporters (SLC2A) in GDM pregnancies. Maternal age and pre-pregnancy body weight were documented. Newborn weights were recorded after delivery. Placentas 37-40-week gestation from control patients (no pregnancy complication) (n = 5), or with GDM (n = 5) were weighed immediately after delivery. Villous samples (4 mm diameter) were collected and divided into specimens; one was fixed in 4% paraformaldehyde for immunostaining using terminal deoxynucleotidyl transferase dUTP-mediated nick-end labeling (TUNEL) and activated caspase-3. The other specimen was snap frozen in liquid nitrogen and stored at -80°C for active caspase-3, poly(ADP-ribose) polymerase (PARP), SLC2A1 and SLC2A3 gene expression analysis. Our results showed that maternal age and pre-pregnancy body weight were significantly higher in the GDM group when compared with those from the controls (P < 0.05). The mean neonatal birth weight and placenta weight were significantly higher in the GDM group compared with that from the controls (P < 0.05). The apoptotic index of placentas (0.05 ± 0.01 v. 0.17 ± 0.04, P < 0.04), active caspase-3 polypeptide fragments and PARP protein were significantly decreased in GDM placentas as compared with controls. Further, the level of placental SLC2A1 protein expression was ∼3-fold higher in GDM placentas. Our results suggest that reduced apoptosis in GDM placentas may contribute to increased placental tissue, which together with enhanced SLC2A1 expression, could play a role in fetal macrosomia.

Gestational diabetes mellitus alters apoptotic and inflammatory gene expression of trophobasts from human term placenta

AIM

Increased placental growth secondary to reduced apoptosis may contribute to the development of macrosomia in GDM pregnancies. We hypothesize that reduced apoptosis in GDM placentas is caused by dysregulation of apoptosis related genes from death receptors or mitochondrial pathway or both to enhance placental growth in GDM pregnancies.

METHODS

Newborn and placental weights from women with no pregnancy complications (controls; N=5), or with GDM (N=5) were recorded. Placental villi from both groups were either fixed for TUNEL assay, or snap frozen for gene expression analysis by apoptosis PCR microarrays and qPCR.

RESULTS

Maternal, placental and newborn weights were significantly higher in the GDM group vs. Controls. Apoptotic index of placentas from the GDM group was markedly lower than the Controls. At a significant threshold of 1.5, seven genes (BCL10, BIRC6, BIRC7, CASP5, CASP8P2, CFLAR, and FAS) were down regulated, and 13 genes (BCL2, BCL2L1, BCL2L11, CASP4, DAPK1, IκBκE, MCL1, NFκBIZ, NOD1, PEA15, TNF, TNFRSF25, and XIAP) were unregulated in the GDM placentas. qPCR confirmed the consistency of the PCR microarray. Using Western blotting we found significantly decreased placental pro-apoptotic FAS receptor and FAS ligand (FASL), and increased mitochondrial anti-apoptotic BCL2 post GDM insult. Notably, caspase-3, which plays a central role in the execution-phase of apoptosis, and its substrate poly (ADP-ribose) polymerase (PARP) were significantly down regulated in GDM placentas, as compared to non-diabetic Control placentas.

CONCLUSION

Maternal GDM results in heavier placentas with aberrant placental apoptotic and inflammatory gene expression that may account, at least partially, for macrosomia in newborns.

Modulation of wolframin expression in human placenta during pregnancy: comparison among physiological and pathological states

The WFS1 gene, encoding a transmembrane glycoprotein of the endoplasmic reticulum called wolframin, is mutated in Wolfram syndrome, an autosomal recessive disorder defined by the association of diabetes mellitus, optic atrophy, and further organ abnormalities. Disruption of the WFS1 gene in mice causes progressive β-cell loss in the pancreas and impaired stimulus-secretion coupling in insulin secretion. However, little is known about the physiological functions of this protein. We investigated the immunohistochemical expression of wolframin in human placenta throughout pregnancy in normal women and diabetic pregnant women. In normal placenta, there was a modulation of wolframin throughout pregnancy with a strong level of expression during the first trimester and a moderate level in the third trimester of gestation. In diabetic women, wolframin expression was strongly reduced in the third trimester of gestation. The pattern of expression of wolframin in normal placenta suggests that this protein may be required to sustain normal rates of cytotrophoblast cell proliferation during the first trimester of gestation. The decrease in wolframin expression in diabetic placenta suggests that this protein may participate in maintaining the physiologic glucose homeostasis in this organ.

Placental development during early pregnancy in sheep: effects of embryo origin on fetal and placental growth and global methylation

The origin of embryos including those created through assisted reproductive technologies might have profound effects on placental and fetal development, possibly leading to compromised pregnancies associated with poor placental development. To determine the effects of embryo origin on fetal size, and maternal and fetal placental cellular proliferation and global methylation, pregnancies were achieved through natural mating (NAT), or transfer of embryos generated through in vivo (NAT-ET), IVF, or in vitro activation (IVA). On Day 22 of pregnancy, fetuses were measured and placental tissues were collected to immunologically detect Ki67 (a marker of proliferating cells) and 5-methyl cytosine followed by image analysis, and determine mRNA expression for three DNA methyltransferases. Fetal length and labeling index (proportion of proliferating cells) in maternal caruncles (maternal placenta) and fetal membranes (fetal placenta) were less (P < 0.001) in NAT-ET, IVF, and IVA than in NAT. In fetal membranes, expression of 5-methyl cytosine was greater (P < 0.02) in IVF and IVA than in NAT. In maternal caruncles, mRNA expression for DNMT1 was greater (P < 0.01) in IVA compared with the other groups, but DNMT3A expression was less (P < 0.04) in NAT-ET and IVA than in NAT. In fetal membranes, expression of mRNA for DNMT3A was greater (P < 0.01) in IVA compared with the other groups, and was similar in NAT, NAT-ET, and IVF groups. Thus, embryo origin might have specific effects on growth and function of ovine uteroplacental and fetal tissues through regulation of tissue growth, DNA methylation, and likely other mechanisms. These data provide a foundation for determining expression of specific factors regulating placental and fetal tissue growth and function in normal and compromised pregnancies, including those achieved with assisted reproductive technologies.

Perinatal outcomes after sonographic detection of isolated short femur in the second trimester

PURPOSE

To determine the association of fetal isolated short femur in the second-trimester ultrasound (US) examination with perinatal outcomes such as small-for-gestational age (SGA) and low-birth weight (LBW) neonates.

METHODS

This is a retrospective cohort study in fetuses routinely assessed by US examination at 18 to 24 weeks during 2006-2009. A fetal isolated short femur was defined as femur length below the 5th percentile and with no chromosomal or structural abnormalities. Fetuses with abdominal circumference below the 5th percentile at the time of US examination were excluded. Each case of short femur was matched with three controls according to gestational age at the time of the US examination.

RESULTS

Sixty-one fetuses met the inclusion criteria. Both the group of women carrying a fetus with isolated short femur and that of women carrying a fetus with normal femur length had similar general and obstetric characteristics. Women carrying a fetus with isolated short femur were significantly more likely to deliver a SGA neonate (19.7% versus 8.7%, p < 0.05) and a LBW neonate (19.7% versus 7.1%, p < 0.05) than women carrying a fetus with normal femur length. Logistic regression analysis found odds ratios for SGA and LBW of 2.6 (95% confidence interval, 1.1-5.9) and 2.9 (95% confidence interval, 1.2-7.1), respectively.

CONCLUSIONS

Isolated short femur in the second-trimester US examination is associated with a subsequent delivery of SGA and LBW neonates.

The characterization of fibrocyte-like cells: a novel fibroblastic cell of the placenta

The placenta is a highly vascularized organ thus angiogenesis is a key process in placental development. The contribution that different cells in the villous stroma play in placental angiogenesis is largely unknown. In this study we identified a novel stromal cell type in sections of term placenta which is morphologically fibroblastic and expressing the fibroblast marker TE-7 but also positive for the monocytic markers CD115 and CD14 and designated these cells as fibrocyte-like cells. Populations of fibrocyte-like cells from the placenta were isolated by two methods: culture of adherence-selected placental cells and, for higher purity, by CD45 fluorescence activated cell sorting (FACS). Fibrocyte-like cell conditioned medium increased endothelial tubule-like structure formation 2-fold versus control medium. Both pro-angiogenic growth factors vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (b-FGF) and the anti-angiogenic factor soluble-Flt were found in the conditioned medium. Neutralizing antibodies against VEGF and b-FGF reduced endothelial cell tubule-like structures to control levels. These data suggests that fibrocyte-like cells, a previously unidentified cell of the villous stroma, may play an important role in the regulation of placental angiogenesis.

Placental development during early pregnancy in sheep: cell proliferation, global methylation, and angiogenesis in the fetal placenta

To characterize early fetal placental development, gravid uterine tissues were collected from pregnant ewes every other day from day 16 to 30 after mating. Determination of 1) cell proliferation was based on Ki67 protein immunodetection; 2) global methylation was based on 5-methyl-cytosine (5mC) expression and mRNA expression for DNA methyltransferases (DNMTs)1,3a, and3b; and 3) vascular development was based on smooth muscle cell actin immunolocalization and on mRNA expression of several factors involved in the regulation of angiogenesis in fetal membranes (FMs). Throughout early pregnancy, the labeling index (proportion of proliferating cells) was very high (21%) and did not change. Expression of 5mC and mRNA forDNMT3bdecreased, but mRNA forDNMT1and3aincreased. Blood vessels were detected in FM on days 18–30 of pregnancy, and their number per tissue area did not change. The patterns of mRNA expression for placental growth factor, vascular endothelial growth factor, and their receptorsFLT1andKDR; angiopoietins 1 and 2 and their receptorTEK; endothelial nitric oxide synthase and the NO receptorGUCY13B; and hypoxia inducing factor 1 α changed in FM during early pregnancy. These data demonstrate high cellular proliferation rates, and changes in global methylation and mRNA expression of factors involved in the regulation of DNA methylation and angiogenesis in FM during early pregnancy. This description of cellular and molecular changes in FM during early pregnancy will provide the foundation for determining the basis of altered placental development in pregnancies compromised by environmental, genetic, or other factors.

Placental gene transfer: transgene screening in mice for trophic effects on the placenta

OBJECTIVE

We hypothesized that gene transfer of select growth factors to the placenta may enhance placental and fetal growth. Thus, we examined the effect of 8 growth factor transgenes on murine placenta.

STUDY DESIGN

Adenoviral-mediated site-specific intraplacental gene transfer of 8 different growth factor transgenes at embryonic day (e) 14 was performed. Transgenes included angiopoietin-1, angiopoietin-2 (Ang-2), basic fibroblast growth factor, hepatocyte growth factor, insulin-like growth factor-1 (IGF-1), placenta growth hormone, platelet-derived growth factor-B (PDGF-B), and vascular endothelial growth factor(121). Fetuses and placentas were harvested at e17 and assessed for survival, gene transfer efficiency, placenta area, and fetal and placental weights.

RESULTS

Efficient gene transfer to the placenta was detected with minimal dissemination to the fetus. Overexpression of IGF-1, PDGF-B, and Ang-2 resulted in an increase in placenta cross-sectional area. Only Ang-2 gene transfer resulted in increased fetal weight, and only Ang-2 and basic fibroblast growth factor resulted in a change in placental weight.

CONCLUSION

Site-specific placental gene transfer results in efficient gene transfer with minimal dissemination to the fetus. Adenoviral-mediated IGF-1, adenoviral-mediated PDGF-B, and adenoviral-mediated Ang-2 significantly increase placenta growth.

Glycaemic control throughout pregnancy and risk of pre-eclampsia in women with type I diabetes

The aim of this study was to examine the influence of pre-pregnancy care and its effect on early glycaemic control and also the effect of glycaemic control in later pregnancy on risk of pre-eclampsia in women with type I diabetes. A prospective cohort study of 290 consecutive nonselected pregnancies in women with type I diabetes was performed from 1991 to 2002. We examined the relationship of monthly glycosylated haemoglobin (HbA1c) level, pre-pregnancy care, parity, diabetes duration, microvascular complications, maternal age, weight and smoking with risk of pre-eclampsia. Pre-eclampsia developed in 31/243 singleton births (12.8%). HbA1c level at 24 weeks was significantly increased in women with pre-eclampsia compared with women without pre-eclampsia (6.0 versus 5.6%, P= 0.017) and was, after nulliparity, the strongest independent predictor of increased risk (OR 1.65 for each 1% increase in HbA1c; P= 0.01). In contrast, there was no relationship between pre-pregnancy care or HbA1c level at booking and risk of pre-eclampsia.

Changes in apoptosis and Bcl-2 expression in human hyperglycemic, term placental trophoblast

Apoptosis and its associated regulatory mechanisms are physiological events crucial to the maintenance of placental homeostasis; imbalance of these processes, however, such as occurs under various pathological conditions, may compromise placenta function and, consequently, pregnancy success. Increased apoptosis occurs in the placentas of pregnant women with several developmental disabilities, while increased Bcl-2 expression is generally associated with pregnancy-associated tumors. Herein, we tested the hypothesis that apoptosis-associated disturbs might be involved in the placental physiopathology subjected to different maternal hyperglycemic conditions. Thus, in the present study we investigated and compared the incidence of apoptosis using TUNEL reaction and Bcl-2 expression, in term-placentas of normoglycemic, diabetic and daily hyperglycemic patients. Tissue samples were collected from 37 placentas, being 15 from healthy mothers with normally delivered healthy babies, and 22 from mothers with glucose disturbances. From these latter 22 patients, 10 showed maternal daily hyperglycemia and 12 were clinically diabetics. Both Bcl-2 expression and apoptotic DNA fragmentation were established and quantified in the trophoblasts of healthy mothers. Compared to these reference values, a higher apoptosis index and lower Bcl-2 expression were disclosed in the placentas of the diabetic women, while in the daily hyperglycemic group, values were intermediate between the diabetic and normoglycemic patients. The TUNEL/Bcl-2 index ratio in the placentas varied from 0.02 to 0.09 for pregnant normoglycemic and diabetic women, respectively, revealing a predominance of apoptosis in the diabetic group. Our findings suggest that hyperglycemia may be a key factor evoking apoptosis in the placental trophoblast, and therefore, is relevant to diabetic placenta function.

Expression of Bcl-2 and p53 at the fetal-maternal interface of rhesus monkey

To study the apoptosis and its mechanism at the fetal-maternal interface of early gestation, localization of apoptotic cells in the implantation sites of the rhesus monkey on day 17, 19, 28 and 34 of pregnancy were first examine by using the TUNEL technique. The expression of Ki67, a molecular marker of proliferating cells, and two apoptotic proteins, B cell lymphoma/leukaemia-2 (Bcl-2) and P53, were then studied by immunohistochemistry. Apoptotic nuclei were observed mainly in the syncytiotrophoblast. Ki67 was confined almost exclusively to cytotrophoblasts. The localization of Bcl-2 protein follows that of the apoptotic nuclei and its expression level increased as the development of the placenta progressed on. P53 was detected to some extent in cytotrophoblasts and syncytiotrophoblast covering the basal feet of the anchoring villi during the late stage of placentation. Based on these observations, it might be suggested that Bcl-2 could be possible to play an interesting role in limiting degree of nuclear degradation and sustaining cell survival in the multi-nucleated syncytiotrophoblast cells during early pregnancy, and P53 could also be essential in regulating the trophoblastic homeostasis by controlling its proliferation or apoptosis.