Cellular growth in human placenta. II. Diabetes mellitus

Gestational age, birth weight, and perinatal complications in mothers with diabetes and impaired glucose tolerance: Japan Environment and Children's Study cohort

We aimed to determine the risk of perinatal complications during delivery in mothers with non-normal glucose tolerance in a large Japanese birth cohort. We analysed data of 24,295 neonate–mother pairs in the Japan Environment and Children’s Study cohort between 2011 and 2014. We included 67 mothers with type 1 diabetes, 102 with type 2 diabetes (determined by questionnaire), 2,045 with gestational diabetes (determined by diagnosis), and 2,949 with plasma glucose levels ≥140 mg/dL (shown by a screening test for gestational diabetes). Gestational age, birth weight, placental weight, and proportions of preterm birth, and labour and neonatal complications at delivery in mothers with diabetes were compared with those in mothers with normal glucose tolerance. Mean gestational age was shorter in mothers with any type of diabetes than in mothers without diabetes. Birth weight tended to be heavier in mothers with type 1 diabetes, and placental weight was significantly heavier in mothers with type 1 and gestational diabetes and elevated plasma glucose levels (all p<0.05). The relative risks of any labour complication and any neonatal complication were 1.49 and 2.28 in type 2 diabetes, 1.59 and 1.95 in gestational diabetes, and 1.22 and 1.30 in a positive screening test result (all p<0.05). The relative risks of preterm birth, gestational hypertension, and neonatal jaundice were significantly higher in mothers with types 1 (2.77; 4.07; 2.04) and 2 diabetes (2.65; 5.84; 1.99) and a positive screening test result (1.29; 1.63; 1.12) than in those without diabetes (all p<0.05). In conclusion, placental weight is heavier in mothers with non-normal glucose tolerance. Preterm birth, gestational hypertension, and jaundice are more frequent in mothers with types 1 and 2 diabetes. A positive result in a screening test for gestational diabetes suggests not only a non-normal glucose tolerance, but also a medium (middle-level) risk of perinatal complications.

Expression of ABC Efflux transporters in placenta from women with insulin-managed diabetes

Drug efflux transporters in the placenta can significantly influence the materno-fetal transfer of a diverse array of drugs and other xenobiotics. To determine if clinically important drug efflux transporter expression is altered in pregnancies complicated by gestational diabetes mellitus (GDM-I) or type 1 diabetes mellitus (T1DM-I), we compared the expression of multidrug resistance protein 1 (MDR1), multidrug resistance-associated protein 2 (MRP2) and the breast cancer resistance protein (BCRP) via western blotting and quantitative real-time polymerase chain reaction in samples obtained from insulin-managed diabetic pregnancies to healthy term-matched controls. At the level of mRNA, we found significantly increased expression of MDR1 in the GDM-I group compared to both the T1DM-I (p<0.01) and control groups (p<0.05). Significant changes in the placental protein expression of MDR1, MRP2, and BCRP were not detected (p>0.05). Interestingly, there was a significant, positive correlation observed between plasma hemoglobin A1c levels (a retrospective marker of glycemic control) and both BCRP protein expression (r = 0.45, p<0.05) and BCRP mRNA expression (r = 0.58, p<0.01) in the insulin-managed DM groups. Collectively, the data suggest that the expression of placental efflux transporters is not altered in pregnancies complicated by diabetes when hyperglycemia is managed; however, given the relationship between BCRP expression and plasma hemoglobin A1c levels it is plausible that their expression could change in poorly managed diabetes.

Placental weight and placental weight-to-birth weight ratio are increased in diet- and exercise-treated gestational diabetes mellitus subjects but not in subjects with one abnormal value on 100-g oral glucose tolerance test

The aim of the present study was to determine whether the placental weight and placental weight-to-birth weight ratio (PW/BW) increased in pregnant women with one abnormal value (OAV) on 100-g oral glucose tolerance test (OGTT) and diet- and exercise-treated, non-insulin-requiring gestational diabetes mellitus (GDM) subjects. The 50-g glucose challenge test (GCT) was administered to 324 pregnant women. Women with abnormal 50-g test received a 100-g, 3-h OGTT using National Diabetes Data Group criteria. Women with GDM and OAV were treated with diet and exercise. Twenty subjects who required insulin or met exclusion criteria were excluded from the study. After the exclusion of 20 subjects, the GDM group consisted of 30 (9.7%) pregnant women and the OAV group consisted of 32 (9.9%) pregnant women. The control group consisted of 242 pregnant women. Birth weight (GDM: 3288.3+/-364.2 g; OAV: 3278.1+/-409.9 g; control group: 3270.6+/-346.5 g) did not differ significantly between groups (P>.05). Significantly higher placental weights (GDM: 694.8+/-152.1 g; OAV: 622.2+/-105.3 g; control group: 610.2+/-116.6 g; P<.01) and PW/BW (GDM: 0.21+/-0.03; OAV: 0.193+/-0.04; control group: 0.188+/-0.04; P<.01) were observed in GDM group compared to OAV and control group. No significant difference was found for OAV group in terms of placental weight and PW/BW compared to the control group. Our data indicated that women with OAV delivered infants and placenta of similar weight to those of normal pregnancies.

Mutations in the glucokinase gene of the fetus result in reduced placental weight

OBJECTIVE

In human pregnancy, placental weight is strongly associated with birth weight. It is uncertain whether there is regulation of the placenta by the fetus or vice versa. We aimed to test the hypothesis that placental growth is mediated, either directly or indirectly, by fetal insulin.

RESEARCH DESIGN AND METHODS

Birth weight and placental weight were measured in 43 offspring of 21 parents with mutations in the glucokinase (GCK) gene (25 had inherited the mutation and 18 had not), which results in reduced fetal insulin secretion. Birth weight, placental weight, umbilical cord insulin, and maternal glucose and insulin concentrations were measured in 573 nondiabetic, healthy, term pregnancies.

RESULTS

GCK mutation carriers were lighter and also had smaller placentas (610 vs. 720 g, P = 0.042). This difference was also seen in 17 discordant sibling pairs (600 vs. 720 g, P = 0.003). GCK mRNA was not detected in the placenta by RT-PCR. In the normal pregnancies, placental weight was strongly correlated with birth weight (r = 0.61, P < 0.001). Cord insulin concentrations were directly related to placental weight (r = 0.28) and birth weight (r = 0.36) (P < 0.001 for both).

CONCLUSIONS

These results suggest that insulin, directly or indirectly, plays a role in placental growth, especially as a mutation in the GCK gene, which is known to only alter fetal insulin secretion, results in altered placental weight. This finding is consistent with the preferential localization of the insulin receptors in the fetal endothelium of the placenta in the last trimester of pregnancy.

Altered perlecan expression in placental development and gestational diabetes mellitus

The proteoglycan perlecan is involved in cell signaling, regulation of growth factor activity, and maintenance of basement membranes. This study aims to investigate the expression of perlecan during placental development and whether hyperglycemia of gestational diabetes mellitus induces the alteration of perlecan expression in placenta. Immunohistochemistry, immunoprecipitation/sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and quantitative real-time PCR were carried out to study the placental perlecan expression at different trimesters of pregnancies and in gestational diabetes mellitus. The perlecan protein was mainly immunolocalized in the trophoblast and vessel basement membranes with some staining in the villous stroma of placental villus. Perlecan was also found to co-localize with laminin and collagen IV in the basement membranes of placenta. The protein and mRNA levels of placental perlecan were significantly decreased as the gestational age increased. However, a significant increase in perlecan expression was observed in the third trimester placentas with gestational diabetes mellitus compared to the gestational age-matched controls. Furthermore, trophoblast cells cultured in a high glucose (30 mM) medium and a high osmotic pressure medium (5.6 mM glucose and 24.4 mM mannitol) showed increased perlecan expression compared to cells cultured in the low glucose (5.6 mM) regular medium. These alterations of perlecan expression may be associated with the structural changes of placenta during maturation. The metabolic effect of high glucose and high osmotic pressure of gestational diabetes mellitus may contribute to the increased perlecan expression of diabetic placentas.

Gestational diabetes induces placental genes for chronic stress and inflammatory pathways

A physiological state of insulin resistance is required to preferentially direct maternal nutrients toward the feto-placental unit, allowing adequate growth of the fetus. When women develop gestational diabetes mellitus (GDM), insulin resistance is more severe and disrupts the intrauterine milieu, resulting in accelerated fetal development with increased risk of macrosomia. As a natural interface between mother and fetus, the placenta is the obligatory target of such environmental changes. However, the molecular basis for the imbalance that leads to fetal, neonatal, and adult metabolic compromises is not well understood. We report that GDM elicits major changes in the expression profile of placental genes with a prominent increase in markers and mediators of inflammation. Within the 435 transcripts reproducibly modified, genes for stress-activated and inflammatory responses represented the largest functional cluster (18.5% of regulated genes). Upregulation of interleukins, leptin, and tumor necrosis factor-alpha receptors and their downstream molecular adaptors indicated an activation of pathways recruiting stress-activated protein/c-Jun NH(2)-terminal kinases. Transcriptional activation of extracellular matrix components and angiogenic activators pointed to a major structural reorganization of the placenta. Thus, placental transcriptome emerges as a primary target of the altered environment of diabetic pregnancy. The genes identified provide the basis to elucidate links between inflammatory pathways and GDM-associated insulin resistance.

Effect of diabetes mellitus on rat placenta cellularity

Transcellular placental maternofetal flux of calcium and magnesium is reduced in diabetic pregnancy in the rat which might be due to changes in placental cellularity. In order to investigate this wet and dry weight, DNA and protein content were measured in placentas from untreated diabetic (D(O)), insulin-treated diabetic (D(I)) and control rats (C) on day 21 of gestation (term=23 days). Wet and dry weights (mg; mean+/-S.E.M.) were 418+/-13, 474+/-19, 416+/-14 and 66+/-3, 75+/-3, 67+/-3 in C, D(O) and D(I) groups, respectively. Total DNA and protein content (mg) was 1.8+/-0.2, 1.7+/-0.1, 1.5+/-0.1 and 50.4+/-2.4, 54.9+/-2.6, 51.9+/-3.3 in C, D(O) and D(I) groups, respectively. The data suggest that placental cellularity is unaffected by maternal diabetes mellitus in the rat and is unlikely to directly affect maternofetal flux of calcium and magnesium.

Placental size and large-for-gestational-age infants in women with abnormal glucose tolerance in pregnancy

AIMS

To determine if the placental size is disproportionately increased in the large-for-gestational age infants in pregnancies complicated by impaired glucose tolerance.

METHODS

A retrospective study was performed on 568 consecutive singleton pregnancies complicated by gestational impaired glucose tolerance controlled with diet and who delivered within a 15-month period. The cases were categorized by the infant birthweight percentile into three groups, i.e. small-for-gestational age (< 10th percentile), appropriate-for-gestational age (10th to 90th percentile) and large-for-gestational age (> 90th percentile). Maternal and infant anthropometric data, glycaemic status, and placental weight-to-birthweight ratio were compared among the three groups.

RESULTS

The infant body mass index and placental weight showed a significantly increasing trend from the small-for-gestational age to the large-for-gestational age groups, but there was no significant difference in the placental weight-to-birthweight ratio, values of the oral glucose tolerance test, or haemoglobin A1c among the three groups. On the other hand, the maternal body mass index before pregnancy and at delivery were significantly higher in the large-for-gestational age group. The placental weight, but not the ratio, was significantly correlated with the maternal body mass index before pregnancy and at delivery (P < 0.001).

CONCLUSIONS

The results indicate that the placenta is not disproportionately bigger, and therefore unlikely to be the cause, in large-for-gestational age infants. Maternal size appeared to be the major determinant of birthweight percentile ranking in pregnancies with gestational impaired glucose tolerance.

Placental weight in diabetic pregnancies

The placenta from 30 women with diabetes mellitus were examined and weighed at delivery. Nineteen of these were from women with overt and eleven from women with gestational diabetes. Eleven placentae from normal pregnancies served as controls. There was no difference between the mean +/- s.d. placental weight for the diabetic group and the control group (609 +/- 148 versus 591 +/- 93 g, NS). The mean placental weight ratios for the diabetic group and the control group were also similar (0.98 +/- 0.23 versus 0.89 +/- 0.15, NS). Moreover, there was no difference between the weights and weight ratios of placentae from women with overt (622 +/- 173 g, 1.02 +/- 0.27) and those with gestational diabetes (586 +/- 90 g, versus 0.90 +/- 0.13). Placental weights correlated with birthweights (r = 0.70, P less than 0.01) and with skinfold thickness measurements fo the infants (r = 0.40, P less than 0.05), but neither with gestational ages (r = 0.15, NS) nor with maternal glycosylated haemoglobin levels in the third trimester (r = 0.24, NS). Among the women with overt diabetes, placental weights were greater in those in White's class B and C than those in class D and R (689 +/- 143 versus 530 +/- 177 g; P less than 0.05). In general, placentae from well controlled diabetic patients were not heavier than those from normal pregnant women, although there was an increase in placental weight in White's class B and C, as compared with those in class D and R.

Histomorphometry of the human placenta in Class B diabetes mellitus

Different morphometric parameters have been applied to the study of the morphological differences between a group of normal placentae and a group of placentae collected from Class B diabetic mothers. The placentae of the diabetics were divided in two groups based on the growth characteristics and neonatal outcome of the infants at birth. It has been shown that the placentae of the appropriate for gestational age infants were morphologically very similar to the control group except for a well-developed villous vascularization. In contrast, the placentae of the large for gestational age infants were shown to differ from the controls by having heavier placentae due mainly to a significant accumulation of non-parenchyma and a moderate increase in parenchymal tissue. Consequently, although there was significantly more villous tissue in these placentae, the surface areas of exchange between mother and fetus in terms of capillary and villous surface areas were only moderately enlarged due to a relatively lower number of villi containing non-parenchymal tissue. However, on a functional basis, despite these morphological differences, the results of this study suggest that placental function is not adversely affected in Class B diabetics, and the perinatal morbidity associated with this condition is probably the result of metabolic abnormalities present in the mother and the fetus.

Placental lipid and glycogen content in human and experimental diabetes mellitus

To assess whether placental DNA, glycogen, and fat are affected by diabetes mellitus and whether the changes correlate with the disturbance in maternal fuels, placentas were examined at delivery in women with normal carbohydrate metabolism, gestational diabetes mellitus, and Classes B to F diabetes and in rats rendered diabetic by the administration of streptozotocin 2 weeks before mating. Plasma glucose values during late pregnancy were higher in patients with Classes B to F diabetes than in the patients with gestational diabetes mellitus so that they were judged to have more severe metabolic disturbances; rats were also divided into groups with "mild" or "severe" diabetes on the basis of blood sugar. In rats, as in humans, diabetes tended to increase placental mass, DNA, glycogen, and lipids. However, the relative changes in glycogen and fat exceeded the alterations in mass and DNA, especially in those with more severe diabetes, so that a true increase in glycogen and fat per placental cell may have occurred. Thus, placental glycogen/DNA and placental triglycerides/DNA significantly exceeded control values in patients with Classes B to F diabetes and in rats with severe diabetes but not in women with gestational diabetes mellitus or rats with mild diabetes. Total placental triglycerides and total placental glycogen were significantly correlated (r = 0.952; p less than 0.001) in rats with experimental diabetes, which suggests that these alterations in placental composition during late pregnancy may share communal dependencies.

The fetal arterial vasculature in placentas of insulin-dependent diabetic mothers

Seventeen placentas from insulin-dependent diabetic women and ten placentas from non-diabetics were studied with angiography. The fresh placentas were injected in both umbilical arteries with barium sulphate suspension. After fixation in formaldehyde, the placentas were X-rayed, intact and after being sliced in 0.8 cm slices. There were two clearly distinguishable types of intracotyledonary arteries. Type A is long, narrow and usually runs in the periphery of the cotyledon; type B is wider and usually runs towards the centre of a cotyledon. The cotyledons were classified according to the distribution of these two types of arteries. Type I contained only A-arteries and Type II, both A- and B-arteries or only B-arteries. Twelve per cent of the cotyledons in the control group belonged to Type I, but in the diabetes group 29 per cent. One block of tissue from every placenta was examined histologically to check that the contrast medium filled the stem villus vessels but not the capillaries in the peripheral villi. The histological sections in both groups were compared. Endarteritis appeared to be a feature of the diabetes placenta. The angiographic findings were compared with results of previous direct light microscopical studies. A high percentage of hypovascular villi was found in placentas with a high number of Type I cotyledons.

Histomorphometry of the placenta of the diabetic women: class A diabetes mellitus

Different morphometric parameters have been applied to the study of the morphological differences between a group of normal placentae and a group of placentae collected from Class A diabetic women. It has shown that although fetal weights were significantly higher in the infants of the diabetic mothers, placental weights showed only a tendency to be heavier than the gestationally matched controls, though the difference was not statistically significant. However, the placentae of the Class A diabetic mothers were shown to differ from the control group by having significantly more parenchymal and villous tissues and a higher cellular content. There were also more surface areas of exchange between mother and fetus, in terms of peripheral and villous capillary surface areas and intervillous space volume. On a functional basis, these morphological changes suggest that, in diabetes mellitus Class A, the placenta can efficiently support the growth of a large fetus, and the perinatal associated with this condition is not likely to be related to decreased or insufficient function of the placenta.

Cellular and biochemical aspects of growth retardation in rat fetuses induced by maternal administration of selected anticancer agents

Single ip injections of 600 mg/kg 5-(3,3-dimethyl-1-triazeno)-imidazole-4-carboxamide (DIC) and 900 mg/kg 5-[3,3-bis(2-chlorethyl)-1-triazeno]-imidazole-4-carboxamide (BIC) were given to pregnant Wistar rats at day 12 and the animals were killed 4 h after injection and at days 13-17 of gestation. Fetal tissues were used to determine total DNA, RNA, and protein and the data used to derive cell number and cell weight, RNA, and protein/cell. Both compounds reduced total fetal body weight, DNA, RNA, and protein but reduction of RNA by BIC was not statistically significant. These effects were observed 4 h after injection, increased with age (days 13-17), and were 3-4 times greater for DIC than BIC. By using the value of 6.2 mumug DNA/cell, cell number and per-cell values for weight, RNA, and protein, and weight: DNA, RNA:DNA, and protein:DNA ratios were computed. The per-cell values and ratios in the DIC-exposed animals were 8-44% greater and in BIC-treated animals 0-11% greater than control animals of the same gestational age. Percentage of body water was the same in the experimental and control animals. The differences in DNA, RNA, and protein are believed to be related to drug-induced growth retardation incident to total fetal DNA reduction resulting in diminished cell number.

DNA polymerase activity in normal and malnourished rat placentas

DNA polymerase activity has been measured in placentas of normal and protein-restricted rats and correlated with the mean percent daily increase in DNA. During normal placental growth, increases in DNA fell rapidly from 13 to 19 days and polymerase activity using denatured DNA template showed a similar pattern falling from values of 10,000 mumu mols dAMP incorporated per mg DNA at 12 days of gestation to 3,100 at 19 days. Protein restriction during gestation reduced placental DNA content after 14 days; by 19 days the DNA content was 81% of normal. The increase in DNA between 13 and 19 days in placentas of malnourished animals paralleled the normal but was significantly lower. Malnutrition markedly reduced enzyme activity at 12, 14, and 16 days; at 19 days, when DNA synthesis has normally ceased, values of DNA polymerase were not different in control and malnourished placentas. Thus DNA polymerase activity using denatured DNA as template, as measured in vitro, was an index of proliferative cell growth in both normal and malnourished placentas. Furthermore, the decrease in enzyme activity in malnourished samples preceded by at least two days any measurable decrease in total placenta DNA content. It is suggested that future clinical application of this technique may provide an index of nutritional status in "at risk" pregnancies.