The pathogenesis of congenital malformations in diabetic pregnancy

Risk for fetal malformations and unfavorable neonatal outcomes in early-onset gestational diabetes mellitus

BACKGROUND

Early-onset gestational diabetes mellitus (GDM) is diagnosed before the 24th gestational week. Since early GDM is associated with first trimester hyperglycemia, many clinicians treat these women as having pre-GDM. However, whether early GDM increases the risk for unfavorable pregnancy outcomes and particularly for fetal malformations to a greater extent than late-onset GDM were not studied sufficiently. We aimed to examine the effect of early-onset GDM on unfavorable pregnancy outcomes.

METHODS

A retrospective cohort study of women with GDM delivering singletons during 2005-2018 was conducted. Women were divided into GDM diagnosed at the first (Trimester1; up to 13.6 weeks; N = 117), the second (Trimester2; up to 23.6 weeks; N = 126), and the third trimester (Trimester3; N = 2334). The primary outcomes were neonatal malformations and a composite of large-for-age newborns, hypoglycemia and hyperbilirubinemia treated with phototherapy. Comparisons were made between early- (Trimester1 + Trimester2-groups) and late-onset GDM (Trimester3-group), and between the three trimesters.

RESULTS

Fetal malformations were low and comparable between the trimester1, trimester2, trimester3 groups (2 (1.7%), 3 (2.4%), and 110 (4.7%), respectively). The composite neonatal complications was similar between the groups (68 (58%), 58 (46%), and 1087 (47%), respectively). In early-onset, the rates of neonatal hypoglycemia and shoulder dystocia were higher than in the late-onset GDM group (OR 95% CI 3.5 [2.0-6.1] and 10.3 [2.4-44.6], respectively). Macrosomia was higher in trimester1 compared with trimester2 and trimester3 cohorts (OR 95% CI 5.3 [1.7-16.9] and 2.8 [1.5-5.2], respectively).

CONCLUSIONS

The risk for fetal malformations was low and comparable between the first, second and third trimester GDM. Since the risks for macrosomia, shoulder dystocia, and neonatal hypoglycemia are higher in early-onset GDM, these women should undergo strict glycemic control, intensive monitoring, and careful neonatal evaluation.

Maternal Hyperglycemia Induces Autonomic Dysfunction and Heart Failure in Older Adult Offspring

AIMS

Offspring exposed to an adverse fetal environment, such as gestational diabetes, may manifest increased susceptibility to several chronic diseases later in life. In the present study, the cardiovascular function of three different ages of offspring from diabetic rats was evaluated.

METHODS AND RESULTS

Diabetes mellitus was induced in pregnant rats by a single dose of streptozotocin (50 mg/kg). The offspring from diabetic (OD) and control rats (OC) were evaluated at three different ages: 6, 12 or 18 months. In the corresponding OC groups, fasting glycemia, baseline mean arterial pressure, and sympathetic tonus increased in the OD rats at 12 (OD12) and 18 (OD18) months of age, while cardiac hypertrophy was observed in all OD groups. Cardiac function evaluation in vivo showed low left ventricular systolic pressure and+dP/dt in the OD18 rats, suggesting a systolic dysfunction. OD12 and OD18 groups showed high left ventricle end-diastolic pressure, suggesting a diastolic dysfunction. OD groups showed an age-related impairment of both baroreflex-mediated tachycardia and baroreflex-mediated bradycardia in OD12 and OD18 rats. In isolated hearts from OD18 rats, both inotropic and tachycardiac responses to increasing isoproterenol were significantly reduced compared to the corresponding OC group.

CONCLUSION

These results suggest that gestational diabetes triggers the onset of hyperglycemia hypertension with impaired baroreflex sensitivity and heart failure in older age of offspring, representing important risk factors for death. Therefore, ensuring optimal glycemic control in diabetic pregnancy is important and serves as a key to preventing cardiovascular disease in the offspring in their older age.

Global Transcriptional Profiling of Granulosa Cells from Polycystic Ovary Syndrome Patients: Comparative Analyses of Patients with or without History of Ovarian Hyperstimulation Syndrome Reveals Distinct Biomarkers and Pathways

Ovarian hyperstimulation syndrome (OHSS) is often a complication of polycystic ovarian syndrome (PCOS), the most frequent disorder of the endocrine system, which affects women in their reproductive years. The etiology of OHSS is multifactorial, though the factors involved are not apparent. In an attempt to unveil the molecular basis of OHSS, we conducted transcriptome analysis of total RNA extracted from granulosa cells from PCOS patients with a history of OHSS (n = 6) and compared them to those with no history of OHSS (n = 18). We identified 59 significantly dysregulated genes (48 down-regulated, 11 up-regulated) in the PCOS with OHSS group compared to the PCOS without OHSS group (p-value < 0.01, fold change >1.5). Functional, pathway and network analyses revealed genes involved in cellular development, inflammatory and immune response, cellular growth and proliferation (including DCN, VIM, LIFR, GRN, IL33, INSR, KLF2, FOXO1, VEGF, RDX, PLCL1, PAPPA, and ZFP36), and significant alterations in the PPAR, IL6, IL10, JAK/STAT and NF-κB signaling pathways. Array findings were validated using quantitative RT-PCR. To the best of our knowledge, this is the largest cohort of Saudi PCOS cases (with or without OHSS) to date that was analyzed using a transcriptomic approach. Our data demonstrate alterations in various gene networks and pathways that may be involved in the pathophysiology of OHSS. Further studies are warranted to confirm the findings.

Environmental health influences in pregnancy and risk of gestational diabetes mellitus: a systematic review

Background

Gestational diabetes mellitus (GDM) is one of the most common pregnancy complications globally. Environmental risk factors may lead to increased glucose levels and GDM, which in turn may affect not only the health of the mother but assuming hypotheses of "fetal programming", also the health of the offspring. In addition to traditional GDM risk factors, the evidence is growing that environmental influences might affect the development of GDM. We conducted a systematic review analyzing the association between several environmental health risk factors in pregnancy, including climate factors, chemicals and metals, and GDM.

Methods

We performed a systematic literature search in Medline (PubMed), EMBASE, CINAHL, Cochrane Library and Web of Science Core Collection databases for research articles published until March 2021. Epidemiological human and animal model studies that examined GDM as an outcome and / or glycemic outcomes and at least one environmental risk factor for GDM were included.

Results

Of n = 91 studies, we classified n = 28 air pollution, n = 18 persistent organic pollutants (POP), n = 11 arsenic, n = 9 phthalate n = 8 bisphenol A (BPA), n = 8 seasonality, n = 6 cadmium and n = 5 ambient temperature studies. In total, we identified two animal model studies. Whilst we found clear evidence for an association between GDM and air pollution, ambient temperature, season, cadmium, arsenic, POPs and phthalates, the findings regarding phenols were rather inconsistent. There were clear associations between adverse glycemic outcomes and air pollution, ambient temperature, season, POPs, phenols, and phthalates. Findings regarding cadmium and arsenic were heterogeneous (n = 2 publications in each case).

Conclusions

Environmental risk factors are important to consider in the management and prevention of GDM. In view of mechanisms of fetal programming, the environmental risk factors investigated may impair the health of mother and offspring in the short and long term. Further research is needed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-13965-5.

Managing asthma in expectant mothers

Pregnancy does not appear to have a consistent effect on the frequency or severity of asthma. The most common cause of worsening asthma in pregnancy is likely to be noncompliance with medication. Emphasizing to the patient in advance that fetal well-being is dependent on maternal well-being may help prevent this.In general, well controlled asthma is not associated with a higher risk of adverse pregnancy outcomes. Essential to successful asthma management is patient education that helps to ensure effective medication use, avoidance of triggers, and prompt treatment. This education should include measurement of peak expiratory flow rate and a written asthma action plan. Most of the medications that are used to control asthma in the general population can be safely used in pregnant women. Inhaled beta-adrenoceptor agonists (beta-agonists), cromolyn sodium (sodium cromoglycate), and inhaled and systemic corticosteroids all appear to be very well tolerated by the fetus. Budesonide and beclomethasone should be considered as the preferred inhaled corticosteroids for the treatment of asthma in pregnancy. Use of the leukotriene receptor antagonists zafirlukast and montelukast in pregnancy is probably safe but should be limited to special circumstances, where they are viewed essential for asthma control. Zileuton should not be used in pregnancy.Acute asthma exacerbations in pregnant women should be treated in a similar manner to that in non-pregnant patients. Maternal blood glucose levels should be monitored periodically in pregnant women receiving systemic corticosteroids because of the deleterious effects of hyperglycemia upon embryos and fetuses. During pregnancy, maternal arterial oxygen saturations should be kept above 95% if possible for fetal well-being. Ambulatory oxygenation should be checked prior to discharge to ensure that women do not desaturate with their daily activities.Acute exacerbations of asthma during labor and delivery are rare. Dinoprost, ergometrine, and other ergot derivatives can cause severe bronchospasm, especially when used in combination with general anesthesia, and should be avoided in asthmatic patients. Pregnant women who have been treated with corticosteroids in the past year may require stress-dose corticosteroids during labor and delivery. Most asthma medications, including oral prednisone, are considered compatible with breast-feeding.

Analysis of epigenetic factors in mouse embryonic neural stem cells exposed to hyperglycemia

BACKGROUND

Maternal diabetes alters gene expression leading to neural tube defects (NTDs) in the developing brain. The mechanistic pathways that deregulate the gene expression remain unknown. It is hypothesized that exposure of neural stem cells (NSCs) to high glucose/hyperglycemia results in activation of epigenetic mechanisms which alter gene expression and cell fate during brain development.

METHODS AND FINDINGS

NSCs were isolated from normal pregnancy and streptozotocin induced-diabetic pregnancy and cultured in physiological glucose. In order to examine hyperglycemia induced epigenetic changes in NSCs, chromatin reorganization, global histone status at lysine 9 residue of histone H3 (acetylation and trimethylation) and global DNA methylation were examined and found to be altered by hyperglycemia. In NSCs, hyperglycemia increased the expression of Dcx (Doublecortin) and Pafah1b1 (Platelet activating factor acetyl hydrolase, isoform 1b, subunit 1) proteins concomitant with decreased expression of four microRNAs (mmu-miR-200a, mmu-miR-200b, mmu-miR-466a-3p and mmu-miR-466 d-3p) predicted to target these genes. Knockdown of specific microRNAs in NSCs resulted in increased expression of Dcx and Pafah1b1 proteins confirming target prediction and altered NSC fate by increasing the expression of neuronal and glial lineage markers.

CONCLUSION/INTERPRETATION

This study revealed that hyperglycemia alters the epigenetic mechanisms in NSCs, resulting in altered expression of some development control genes which may form the basis for the NTDs. Since epigenetic changes are reversible, they may be valuable therapeutic targets in order to improve fetal outcomes in diabetic pregnancy.

Hyperglycemia: GDNF-EGR1 pathway target renal epithelial cell migration and apoptosis in diabetic renal embryopathy

Maternal hyperglycemia can inhibit morphogenesis of ureteric bud branching, Glial cell line-derived neurotrophilic factor (GDNF) is a key regulator of the initiation of ureteric branching. Early growth response gene-1 (EGR-1) is an immediate early gene. Preliminary study found EGR-1 persistently expressed with GDNF in hyperglycemic environment. To evaluate the potential relationship of hyperglycemia-GDNF-EGR-1 pathway, in vitro human renal proximal tubular epithelial (HRPTE) cells as target and in vivo streptozotocin-induced mice model were used. Our in vivo microarray, real time-PCR and confocal morphological observation confirmed apoptosis in hyperglycemia-induced fetal nephropathy via activation of the GDNF/MAPK/EGR-1 pathway at E12-E15. Detachment between ureteric branch and metanephrons, coupled with decreasing number and collapse of nephrons on Day 1 newborn mice indicate hyperglycemic environment suppress ureteric bud to invade metanephric rudiment. In vitro evidence proved that high glucose suppressed HRPTE cell migration and enhanced GDNF-EGR-1 pathway, inducing HRPTE cell apoptosis. Knockdown of EGR-1 by siRNA negated hyperglycemic suppressed GDNF-induced HRPTE cells. EGR-1 siRNA also reduced GDNF/EGR-1-induced cRaf/MEK/ERK phosphorylation by 80%. Our findings reveal a novel mechanism of GDNF/MAPK/EGR-1 activation playing a critical role in HRPTE cell migration, apoptosis and fetal hyperglycemic nephropathy.

Diabetic and metabolic programming: mechanisms altering the intrauterine milieu

A wealth of epidemiological, clinical, and experimental studies have been linked to poor intrauterine conditions as well as metabolic and associated cardiovascular changes postnatal. These are novel perspectives connecting the altered intrauterine milieu to a rising number of metabolic diseases, such as diabetes, obesity, and hypercholesterolemia as well as the Metabolic Syndrome (Met S). Moreover, metabolic associated atherosclerotic diseases are connected to perigestational maternal health. The "Thrifty Phenotype Hypothesis" introduced cross-generational links between poor conditions during gestation and metabolic as well as cardiovascular alterations postnatal. Still, mechanisms altering the intrauterine milieu causing metabolic and associated atherosclerotic diseases are currently poorly understood. This paper will give novel insights in fundamental concepts connected to specific molecular mechanisms "programming" diabetes and associated metabolic as well as cardiovascular diseases.

The effect of insulin signaling on female reproductive function independent of adiposity and hyperglycemia

Physiological states of insulin resistance such as obesity and diabetes have been linked to abnormalities in female reproductive function. However, it is difficult to distinguish the direct effects of impaired insulin signaling from those of adiposity or hyperglycemia because these conditions often coexist in human syndromes and animal models of insulin resistance. In this study, we used lean, normoglycemic mouse lines with differing degrees of hyperinsulinemia and insulin receptor (Insr) expression to dissect the effects of altered insulin signaling on female reproduction. All three mouse lines [Ttr-Insr(-/-), Insr(+/-), and Insr(+/+) (wild type)] are able to maintain fertility. However, the insulin-resistant and hyperinsulinemic mice demonstrate altered duration of estrous cycles as well as aberrant distribution and morphology of ovarian follicles. These effects appear to be independent of hyperandrogenism in the mice. Pregnancy studies indicate decreased success in early progression of gestation. In successful pregnancies, decreased embryo weights and increased placental calcification also implicate altered insulin signaling in later gestational effects. Thus, abnormal insulin signaling, independent of adipose tissue mass, adipokine expression levels, and hyperglycemia, can affect parameters of the female hypothalamic-pituitary-gonadal axis and pregnancy outcomes.

Activities of cyclooxygenases, and levels of prostaglandins E2 and F2alpha, in fetopathy associated with experimental diabetic gestation

AIM

The present study investigated the cyclooxygenase (COX) pathway to elucidate any changes that may be involved in the mechanism(s) underlying diabetic fetopathy.

METHODS

Diabetes was induced in female rats (n=12) by two successive daily injections of 55 mg/kg streptozotocin, while control animals (n=10) were injected with a buffer solution; hyperglycaemia was confirmed by blood glucose levels greater than 11 mmol/L. The study female rats were made pregnant and, on day 15 of gestation, the rats were sacrificed, and the fetuses, placentas and membranes dissected out of the uterine horns. Following morphological examination, the fetuses, placentas and membranes were homogenized, and used to measure COX activities and prostaglandin (PG) E(2) and PGF(2alpha) levels.

RESULTS

Fetuses from diabetic mothers exhibited significantly (P<0.05) shorter crown-to-rump lengths, lower body weights and heavier placental weights. The activity of COX-1 in the fetuses, placentas and membranes from diabetic mothers represented a small percentage of total COX activity compared with that of COX-2. The presence of a COX-1 inhibitor in the control and diabetic rats was investigated and found to be negative. The activity of COX-2 in malformed fetuses from diabetic mothers was significantly lower (P<0.05) compared with non-malformed fetuses from control and diabetic mothers. The mean level of PGE(2) in fetuses from diabetic mothers was significantly (P<0.05) lower than that in controls. In contrast, the biggest increases in PGF(2alpha) were observed in the malformed diabetic fetuses, placentas and membranes.

CONCLUSION

The increased production of PGF(2alpha) probably proceeds, at least in part, independently of the COX pathway and via the isoprostane route. However, it is unclear whether the relatively high levels of PGF(2alpha) are causally related to, or simply coincidental with, fetal malformation.

The levels of vascular endothelial growth factor-A and placental growth factor-2 in embryopathy associated with experimental diabetic gestation

The objective of this study was to investigate the role of vascular endothelial growth factor-A (VEGF-A) and placental growth factor-2 (PlGF-2) in fetal malformations associated with maternal diabetes. Diabetes was induced in female rats. Diabetic and control female rats were made pregnant. On Day 15 of gestation, rats were sacrificed and embryos and their placentas and membranes were dissected out of the uterine horns. Following morphological examination, embryos and their placentas and membranes were homogenized and used for assayed of VEGF-A and PlGF-2 levels. Embryos of diabetic mothers, exhibited significantly (P < 0.05) shorter crown-to-rump lengths, smaller weights, and heavier placental weights. Experimentally induced maternal diabetes was accompanied by decreased VEGF-A in embryos and associated structures. The levels of PlGF-2 in non-malformed embryos of diabetic gestation and their placentas were significantly (P < 0.05) lower than the average of controls. These results might indicate defective vascularization with a consequent morphological or anatomical anomalies or more subtle biochemical or metabolic changes. In diabetic mothers, a statistically significant (P < 0.05) decrease was noted in the level of VEGF-A in plasma of diabetic rats with a small non-significant decrease in PlGF-2. Like many other diabetic complications, diabetes-induced embryopathies might have vascular origin and correcting the disturbances in these angiogenic factors might help decrease the incidence of malformation in diabetic gestation.

Pregnancy in women with diabetes--after the CEMACH report, what now?

The second of three studies being undertaken by the Confidential Enquiry into Maternal and Child Health (CEMACH) has recently reported its findings and recommendations. The standards of diabetes and maternal care and the outcomes of 3808 pregnancies in England, Wales and Northern Ireland are described. Pre-pregnancy planning and care before conception is poor. Stillbirth rate (26.8 per thousand) and perinatal mortality (41.8 per thousand) were 4-5 times higher than the background population, and congenital anomaly (41.8 per thousand) double the background rate. Type 2 diabetes now represents 27.3% of pre-gestational diabetes and more often of ethnic minority and deprived background than Type 1 diabetes. The ideals of the Diabetes National Service Framework and the target of the Saint Vincent declaration are far from being achieved. Much can be done to improve the outcomes of pregnancy within existing resources with better systems and organization of care. However, if significant progress is to be made, it is incumbent upon health-care professionals and health-care commissioners to direct resources specifically at improving pre-pregnancy and maternity services. Research is needed firstly to analyse in greater detail the wealth of data collected in the CEMACH survey and consider the implications of health-care costs. Further research to discover ways of reducing the adverse outcomes is urgently required. The need to educate, motivate and bring about improved pre-pregnancy care in women with diabetes is a priority.

Experimental mechanisms of diabetic embryopathy and strategies for developing therapeutic interventions

A high frequency of birth defects is seen in infants born to diabetic mothers. The mechanisms by which maternal hyperglycemia, the major teratogenic factor, induces embryonic malformations remain to be addressed. It has been shown that increases in programmed cell death are one of the factors causing embryonic malformations. Hyperglycemia-induced apoptosis is associated with oxidative stress, lipid peroxidation, and decreased antioxidant defense capacity in the embryos. Recent studies have revealed that mitogen-activated protein kinases as intracellular signaling factors are involved in hyperglycemia-induced embryopathy. Based on the findings, interventions to prevent embryonic malformations have been explored. Strategies include supplementation of molecules that are deficient in the embryos under hyperglycemic conditions and antioxidants to alleviate the adverse effects of oxidative stress. The ultimate goal is to develop multi-nutrient dietary supplements to eliminate embryonic abnormalities induced by maternal diabetes.

Altered gene expression with abnormal patterning of the telencephalon in embryos of diabetic Albino Swiss mice

AIMS/HYPOTHESIS

Several studies have shown that maternal diabetes increases the risk of congenital malformations in various organ systems including the neural tube. The present study analysed molecular and morphological changes in the forebrain of embryos from diabetic Albino Swiss mice.

METHODS

Maternal diabetes-induced morphological changes in the forebrain were examined histologically. Cell proliferation index was assayed by BrdU labelling. In situ hybridisation and quantitative real-time PCR were used to analyse the expression of genes coding for sonic hedgehog ( Shh), Nkx2.1, brain factor-1 ( BF-1) and bone morphogenetic protein-4 ( Bmp4) that control forebrain patterning.

RESULTS

There were no distinguishable abnormalities in the forebrain of embryos from diabetic pregnancies on embryonic day 0.5. At embryonic day 11.5, embryos of diabetic pregnancies displayed a fusion and thickening of the ventral telencephalic neuroepithelium and a partial absence of the dorsal telencephalon, indicating a severe patterning defect in the dorsoventral axis of the telencephalon. The cell proliferation index was also higher in the ventral telencephalon of these embryos. Molecular analyses indicated that expression of Shh, Nkx2.1 and BF-1 was increased and their expression domains expanded dorsally in the ventral telencephalon in embryos of diabetic mice at embryonic day 11.5. The expression of Bmp4 was reduced in the dorsal forebrain of these embryos. At embryonic day 8.5, only Shh expression was increased.

CONCLUSIONS/INTERPRETATION

Altered expression of various genes involved in dorsoventral patterning of the forebrain is associated with forebrain malformations in embryos of diabetic mice.

In human gestational diabetes mellitus congenital malformations are related to pre-pregnancy body mass index and to severity of diabetes

AIMS/HYPOTHESIS

This study analysed the relationship between congenital malformations (CM) and severity of gestational diabetes mellitus.

METHODS

A cohort of 2060 infants of mothers with gestational diabetes was studied. Universal screening and 3(rd) Workshop-Conference criteria were used to diagnose gestational diabetes. The severity of diabetes was assessed on the basis of previous hyperglycaemia, blood glucose values in diagnostic OGTT, area under the glucose curve, gestational age and HbA(1)c at diagnosis, insulin requirements during pregnancy, and OGTT after delivery. Potentially confounding variables (age, pre-pregnancy BMI, smoking) were considered. The relationship of potential predictors with CM was analysed with several multivariate logistic regression analyses.

RESULTS

The rate of CM was 6% for minor and 3.8% for major malformations (1.4% heart, 0.8% renal/urinary, 0.7% skeletal, 0.3% hypospadias, 0.2% central nervous system, 0.2% cleft lip/palate, 0.1% digestive tract, 0.3% other). In the final models, forward logistic regression analysis identified pre-pregnancy BMI as the predictor of CM (area under receiver operating characteristic curve 0.616); in the backward analysis additional predictors were 1-h blood glucose in diagnostic OGTT and gestational age at diagnosis (area under receiver operating characteristic curve 0.646). Both BMI and severity of gestational diabetes were predictors of heart and minor CM, whereas BMI predicted renal/urinary CM and severity of diabetes predicted skeletal CM.

CONCLUSIONS/INTERPRETATION

In these infants of mothers with gestational diabetes, severity of diabetes and pre-pregnancy BMI were predictors of CM, in accordance with the well-documented pathogenic role of BMI (in the general population) and hyperglycaemia (in diabetic pregnancy). BMI was the main predictor of more prevalent CM.

Iron and oxidative stress in pregnancy

Pregnancy, mostly because of the mitochondria-rich placenta, is a condition that favors oxidative stress. Transitional metals, especially iron, which is particularly abundant in the placenta, are important in the production of free radicals. Protective mechanisms against free radical generation and damage increase throughout pregnancy and protect the fetus, which, however, is subjected to a degree of oxidative stress. Oxidative stress peaks by the second trimester of pregnancy, ending what appears to be a vulnerable period for fetal health and gestational progress. Conditions restricted to pregnancy, such as gestational hypertension, insulin resistance and diabetes, exhibit exaggerated indications of free radical damage. Antioxidants as well as avoidance of iron excess ameliorate maternal and early fetal damage. In rats both iron deficiency and excess result in free radical mitochondrial damage. Estimates of gestational iron requirements and of the proportion of iron absorbed from different iron supplemental doses suggest that with present supplementation schemes the intestinal mucosal cells are constantly exposed to unabsorbed iron excess and oxidative stress. Unpublished work carried out in Mexico City with nonanemic women at midpregnancy indicates that 60 mg/d of iron increases the risk of hemoconcentration, low birth weight and premature birth and produces a progressive decline in plasma copper. These risks are not observed in women supplemented with 120 mg iron once or twice per week. Studies on the influence of iron supplementation schemes on oxidative stress are needed.

Diabetic embryopathy in C57BL/6J mice. Altered fetal sex ratio and impact of the splotch allele

Maternal diabetes (types 1 and 2) induces a broad array of congenital malformations, including neural tube defects (NTDs), in humans. One of the difficulties associated with studying diabetic embryopathy is the rarity of individual malformations. In an attempt to develop a sensitive animal model for maternal diabetes-induced NTDs, the present study uses chemically induced diabetes in an inbred mouse model with or without the splotch (Sp) mutation, a putatively nonfunctional allele of Pax3. Pax3 deficiency has been associated with an increase in NTDs. Female C57BL/6J mice, either with or without the Sp allele, were injected intravenously with alloxan (100 mg/kg), and plasma glucose was measured 3 days later. A wide range of hyperglycemia was induced, and these diabetic mice were bred to C57BL/6J males, some carrying the Sp allele. Gestational-day-18 fetuses were examined for developmental malformations. Fetuses from matings in which either parent carried the Sp allele were genotyped by polymerase chain reaction. Maternal diabetes significantly decreased fetal weight and increased the number of resorptions and malformations, including NTDs. A significant correlation was found between the level of maternal hyperglycemia and the malformation rate. The sex ratio for live fetuses in diabetic litters was significantly skewed toward male fetuses. Matings involving the Sp allele yielded litters with significantly higher percentages of maternal diabetes-induced spina bifida aperta but not exencephaly, and this increase was shown to be associated with the presence of a single copy of the Sp allele in affected fetuses. Thus, Pax3 haploinsufficiency in this murine model of diabetic embryopathy is associated with caudal but not cranial NTDs.

Present and future perspectives on the use of free or encapsulated pancreatic islet cell transplantation as a treatment of pregnancy complicated by type 1 diabetes

Pregnancies complicated by insulin-dependent diabetes mellitus (IDDM) pose significant health risks to both the mother and her developing fetus. Congenital malformations in the offspring of diabetic mothers have an incidence which is 2-5 times that seen in the background. Euglycemia in the first trimester of pregnancy can reduce this incidence, but achieving euglycemia with conventional exogenous insulin therapy is both costly and difficult. Even with intense insulin dosage adjustments, the blood glucose profile of the diabetic pregnant patient does not mimic that seen in nondiabetic patients. Both the difficulties and inadequacies of conventional therapy for IDDM-complicated pregnancy provide a stimulus for research to develop improved therapeutic modalities. Islet transplantation holds great promise as a treatment for pregnancies complicated by IDDM. This article reviews the current status of islet transplantation including the use of immunomodulation and immunoisolation techniques and their potential use for the treatment of IDDM pregnancies.

The expanding clinical phenotype of the tRNA(Leu(UUR)) A-->G mutation at np 3243 of mitochondrial DNA: diabetic embryopathy associated with mitochondrial cytopathy

We describe a family which demonstrates and expands the extreme clinical variability now known to be associated with the A-->G transition at nucleotide position 3243 of the mitochondrial DNA. The propositus presented at birth with clinical manifestations consistent with diabetic embryopathy including anal atresia, caudal dysgenesis, and multicystic dysplastic kidneys. His co-twin was normal at birth, but at 3 months of life, presented with intractable seizures later associated with developmental delay. The twins' mother developed diabetes mellitus type I at the age of 20 years and gastrointestinal problems at 22 years. Since age 19 years, the maternal aunt has had recurrent strokes, seizures, mental deterioration and deafness, later diagnosed as MELAS syndrome due to the tRNA(Leu(UUR)) A-->G mutation. A maternal uncle had diabetes mellitus type I, deafness, and normal intellect, and died at 35 years after recurrent strokes. This pedigree expands the known clinical phenotype associated with tRNA(Leu(UUR)) A-->G mutation and raises the possibility that, in some cases, diabetic embryopathy may be due to a mitochondrial cytopathy that affects both the mother's pancreas (and results in diabetes mellitus and the metabolic dysfunction associated with it) and the embryonic/fetal and placental tissues which make the embryo more vulnerable to this insult.

High glucose concentration inhibits migration of rat cranial neural crest cells in vitro

Cranial neural crest cells give rise to a large part of the facial structures, and disturbed development of these cells may therefore cause congenital malformations affecting the head and face. We studied the effects of increased glucose concentration on the migration and development of cranial neural crest cells, maintained in vitro for 48 h. Pre-migratory cranial neural crest cells were removed from embryos of normal and diabetic rats on gestational day 9. After 24 h in 10 mmol/l glucose the cells were exposed to glucose concentrations of 10, 30, or 50 mmol/l for another 24 h. The cultures were photographed at 24 h and 48 h in a phase-contrast microscope to evaluate cell morphology, cell number, and cell migration. Exposure to 50 mmol/l glucose reduced the total number of neural crest cells, their mean migratory distance and migratory area expansion compared to cells cultured in 10 mmol/l glucose. To investigate the effect of antioxidant agents, high glucose cultures were studied after addition of N-acetylcysteine (NAC), or superoxide dismutase (SOD). Addition of NAC diminished the inhibitory effect of high glucose, whereas SOD did not offer any improvement in cell development. Neural crest cell culture from embryos of diabetic rats showed reduced cell migration in vitro at all glucose concentrations compared to normal cells. In addition, the cells from embryos of diabetic rats showed reduced migratory area expansion after culture in the basal 10 mmol/l glucose concentration, indicating that maternal diabetes permanently influences the future development of premigratory cranial neural crest cells. These findings indicate that high glucose concentration inhibits cranial neural crest development in vitro, and that antioxidant therapy may diminish this inhibition. Free radical oxygen species may be involved in the induction of malformations and antioxidants may therefore have a role in future attempts to block the teratogenic effects of diabetic pregnancy.