Hydatidiform mole: an ultrastructural analysis of syncytiotrophoblast surface organization

Epigenetic Dysregulation of Trophoblastic Gene Expression in Gestational Trophoblastic Disease

Gestational trophoblastic diseases (GTDs) have not been investigated for their epigenetic marks and consequent transcriptomic changes. Here, we analyzed genome-wide DNA methylation and transcriptome data to reveal the epigenetic basis of disease pathways that may lead to benign or malignant GTDs. RNA-Seq, mRNA microarray, and Human Methylation 450 BeadChip data from complete moles and choriocarcinoma cells were bioinformatically analyzed. Paraffin-embedded tissues from complete moles and control placentas were used for tissue microarray construction, DNMT3B immunostaining and immunoscoring. We found that DNA methylation increases with disease severity in GTDs. Differentially expressed genes are mainly upregulated in moles while predominantly downregulated in choriocarcinoma. DNA methylation principally influences the gene expression of villous trophoblast differentiation-related or predominantly placenta-expressed genes in moles and choriocarcinoma cells. Affected genes in these subsets shared focal adhesion and actin cytoskeleton pathways in moles and choriocarcinoma. In moles, cell cycle and differentiation regulatory pathways, essential for trophoblast/placental development, were enriched. In choriocarcinoma cells, hormone biosynthetic, extracellular matrix-related, hypoxic gene regulatory, and differentiation-related signaling pathways were enriched. In moles, we found slight upregulation of DNMT3B protein, a developmentally important de novo DNA methylase, which is strongly overexpressed in choriocarcinoma cells that may partly be responsible for the large DNA methylation differences. Our findings provide new insights into the shared and disparate molecular pathways of disease in GTDs and may help in designing new diagnostic and therapeutic tools.

Pre-eclampsia is associated with an increase in trophoblast glycogen content and glycogen synthase activity, similar to that found in hydatidiform moles

Pre-eclampsia is a placental disorder, but until now, biochemical details of dysfunction have been lacking. During an analysis of the oligosaccharide content of syncytiotrophoblast microvesicles purified from the placental chorionic villi of 10 primigravid women with proteinuric pre-eclampsia, we found an excess of glycogen breakdown products. Further investigation revealed a 10-fold increase in glycogen content (223 +/- 117 micrograms glycogen/mg protein), when compared with controls matched for gestational age at delivery (23 +/- 18 micrograms glycogen/mg protein) (P < 0.01). This was confirmed by examination of electron micrographs of chorionic villous tissue stained for glycogen. The increase in glycogen content was associated with 16 times more glycogen synthase (1,323 +/- 1,013 relative to 83 +/- 96 pmol glucose/mg protein per min) (P < 0.001), and a threefold increase in glycogen phosphorylase activity (2,280 +/- 1,360 relative to 700 +/- 540 pmol glucose/mg protein per min; P < 0.05). Similar changes in glycogen metabolism were found in trophoblast microvesicles derived from hydatidiform moles. Glycogen accumulation in villous syncytiotrophoblast may be a metabolic marker of immaturity of this cell which is unable to divide. The implications of these findings with regard to the pathogenesis of pre-eclampsia are discussed.

Partial hydatidiform moles have impaired differentiated function (human chorionic gonadotropin and human placental lactogen secretion) in response to epidermal growth factor and 8-bromo-cyclic adenosine monophosphate

OBJECTIVE

The null hypothesis is that partial hydatidiform moles have normal differentiated function (human chorionic gonadotropin and human placental lactogen secretion) in response to epidermal growth factor and 8-bromo-cyclic adenosine monophosphate.

STUDY DESIGN

Two complete moles, 10 partial hydatidiform moles, and 19 normal first-trimester placentas in monolayer culture were exposed to 10 ng/ml epidermal growth factor, 1 mmol/L 8-bromo-cyclic adenosine monophosphate plus 1 mmol/L theophylline, or control. Human chorionic gonadotropin and human placental lactogen secretion was measured. Frequency of response to stimuli was compared by chi 2 analysis, and hormone secretion was compared by analysis of variance.

RESULTS

Partial moles demonstrated reduced frequencies of response of human chorionic gonadotropin and human placental lactogen to epidermal growth factor (partial moles 2/8 and 2/8, respectively; normal placentas 16/19 and 7/18, respectively; p less than 0.025) and of human chorionic gonadotropin to 8-bromo-cyclic adenosine monophosphate (partial moles 3/5, normal placentas 13/16; p less than 0.005).

CONCLUSION

Partial hydatidiform moles demonstrate impaired human chorionic gonadotropin and human placental lactogen secretory responsiveness to epidermal growth factor and cyclic nucleotides in comparison with normal first-trimester trophoblast.

Confocal and conventional immunofluorescent and immunogold electron microscopic localization of collagen types III and IV in human placenta

Confocal and conventional indirect immunofluorescence and immunogold electron microscopic methods were applied to examine the distribution of extracellular matrix constituents (collagens types III and IV) in the villi of immature and term human placentae. The immunofluorescence study revealed that collagen type III is more distinct in the villous stroma of term placenta as compared with that of the first trimester. Collagen type IV was detected mainly in endothelial and epithelial basement membranes and interestingly also to a certain extent in the stroma. Results obtained using immunoelectron microscopy support the proposal that collagen types III and IV are characteristic of stromal and basement membranes, respectively. Stromal collagen type IV is apparently localized in association with the interstitial types of collagen (I and III), in the villous stroma of term placenta.

Surface and branching of placental villi in early abortion: relationship to karyotype. Scanning electron microscopic study

The placental villi of 61 early abortions with known karyotype and 7 legally induced abortions were investigated by scanning electron microscopy and documented in standardised enlargements. Five groups were established from the findings: uniformly branched villi with a velvety surface (group A) were found in 4 of the 7 induced abortions, abundant syncytial sprouts (group B) in 4 of the 6 cases with monosomy X; all 5 cases of triploidy were classified in the group bulbous or spherical villi (group C); 13 out of 25 cases of trisomy were found to have little branching and a surface densely covered with microvilli (group D), while 14 out of the 25 cases of euploidy belonged in the group with slender villi and surface with focal areas of denudation (group E). Forty of the 68 cases were properly assignable to the correct groups (58.8%). The non-uniformity of the villous morphology in the case of induced abortions shows that there is no uniform development of the (early) placenta. The variable morphology seen in abortions with euploidy reflects the various mechanisms of abortion applicable to this group.