Formalin-fixed Paraffin-embedded Placental Tissues Research Articles

Technical considerations for placental tissue processing and the subsequent impact on genome-wide DNA methylation analysis

To assess the impact of postnatal processing on placental DNA methylation, array data from flash-frozen placental tissue was compared to perfluorocarbon-immersed and formalin-fixed paraffin-embedded placental tissue. We observed that tissue exposed to perfluorocarbon showed no significant DNA methylation differences when compared to unprocessed tissue, while formalin processing altered the quality and reliability of the data produced on the DNA methylation array platform. Placental DNA methylation allows for the study of gene–environment interactions that influence the fetal environment and development. Our study highlights that placental post-processing techniques must be considered in the evaluation and interpretation of epigenetic studies.

Maternal opioid use disorder: Placental transcriptome analysis for neonatal opioid withdrawal syndrome

Excessive prenatal opioid exposure may lead to the development of Neonatal Opioid Withdrawal Syndrome (NOWS). RNA-seq was done on 64 formalin-fixed paraffin-embedded placental tissue samples from 32 mothers with opioid use disorder, with newborns with NOWS that required treatment, and 32 prenatally unexposed controls. We identified 93 differentially expressed genes in the placentas of infants with NOWS compared to unexposed controls. There were 4 up- and 89 downregulated genes. Among these, 7 genes CYP1A1, APOB, RPH3A, NRXN1, LINC01206, AL157396.1, UNC80 achieved an FDR p-value of <0.01. The remaining 87 genes were significant with FDR p-value <0.05. The 4 upregulated, CYP1A1, FP671120.3, RAD1, RN7SL856P, and the 10 most significantly downregulated genes were RNA5SP364, GRIN2A, UNC5D, DMBT1P1, MIR3976HG, LINC02199, LINC02822, PANTR1, AC012178.1, CTNNA2. Ingenuity Pathway Analysis identified the 7 most likely to play an important role in the etiology of NOWS. Our study expands insights into the genetic mechanisms of NOWS development.

MiR-15b-5p promotes expression of proinflammatory cytokines in human placenta by inhibiting Apelin signaling pathway

IntroductionThe timing of parturition at end of human gestation may be controlled by fetal signals. The signaling molecules contributing to activation of human labor may be mediated by fetal exosomes. In this study, we focused on investigation of the role of microRNAs (miRNAs) derived from fetal exosomes in the regulation of human placental gene expression. MethodsUsing immunofluorescent labeling, array-based miRNA profiling assay, target prediction analysis, and conducting a variety of biochemical approaches including miRNA mimics, dual-luciferase, siRNA-mediated gene silencing, and immunohistochemical staining assay in primary trophoblast culture and formalin-fixed paraffin-embedded placental tissues, we examined whether fetal exosomal miRNAs can stimulate expression of proinflammatory mediators in human placenta. ResultsWe showed placental uptake of exosomes derived from the umbilical artery, and found that 9 fetal exosomal miRNAs: let-7i-5p, miR-185-5p, miR-15b-5p, miR-376c-3p, miR-548d-5p, miR-92b-3p, miR-16-5p, and miR-1301-3p were significantly increased in placentas of women delivering following term labor compared to those delivering by Cesarean section in the late preterm period. Target prediction analysis identified miR-15b-5p of particular interest, because one of its predicted targets is Apelin, a potent inhibitor of proinflammatory mediators. We further found that miR-15b-5p repressed Apelin protein levels and activated pro-labor hormones and cytokines including IL-1, IL-6, IL-8, and TNF-α. DiscussionThese data suggest a potential fetal-to-placental signal that could play a role in the length of human gestation and onset of human labor.

GABA receptor A α3 subunit can be involved in the pathophysiology of preeclampsia

GABA receptor A α3 subunit can be involved in the pathophysiology of preeclampsia

Trophoblast calcyclin is elevated in placental tissue from patients with early pre-eclampsia.

The aetiology of pre-eclampsia is thought to originate from aberrant spiral artery remodelling and invasion evoking cellular oxidative stress. Previously, we discovered differentially expressed proteins in trophoblast cells of pre-eclamptic pregnancies. One of these proteins is calcyclin (S100A6); a Ca(2+)-binding protein associated with cellular stress response. By immunohistochemistry on formalin-fixed paraffin-embedded placental tissue, calcyclin expression was compared between women with early pre-eclampsia (n=72) and non-hypertensive control patients (n=66) (χ(2), p=0.006) blindly by two observers. Significantly more intense staining was seen in trophoblast cells of pre-eclamptic pregnancies compared to control placentas suggesting that trophoblast calcyclin is elevated in early pregnancy.

The human placenta from heavy smokers: evaluation of vasoactive peptides by immunohistochemistry

The study aimed to demonstrate the expression of nitric oxide converting enzyme, nitric oxide synthase (e-NOS), and endothelin-1 (Et-1) in formalin-fixed paraffin-embedded placental tissue, and to demonstrate a difference in staining intensity between heavy smokers and non-smokers. Term placentas from pregnancies from otherwise healthy women smoking 15 or more cigarettes per day (heavy smokers) and term placentas from a matching group of non-smokers were included. The antibodies for Et-1 and e-NOS are recommended for cryostat sections. We evaluated the antibodies on paraffin-embedded tissue combined with the streptavidin-biotin-peroxidase technique. Et-1 and e-NOS were demonstrated in the placental vasculature, the trophoblast, and the amnion. A blinded comparative study showed no reproducible significant differences in the staining intensity of the antigen-antibody reaction to Et-1 and e-NOS between the two groups.

Placental Fas and Fas Ligand Expression in Normal Early, Term and Molar Pregnancy

To clarify the Fas and Fas-ligand status of normal and molar trophoblast, the expression of Fas and FasL by placental trophoblast populations in partial and complete hydatidiform moles was compared with that in normal first trimester and term pregnancies using an avidin-biotin peroxidase technique on frozen and formalin-fixed paraffin-embedded placental tissues with both monoclonal and polyclonal antibodies. The TUNEL technique was used to detect apoptotic cells in the same tissues. The immunoreactivity for Fas and Fas-ligand was comparable with both monoclonal and polyclonal antibodies on frozen as well as paraffin-embedded sections. In normal early and molar pregnancy there was strong FasL expression by villous cytotrophoblast and syncytiotrophoblast. However, there were significant differences in FasL expression by trophoblast subpopulations in both early and term normal pregnancy and between the same trophoblast subpopulation at different gestations, with FasL staining generally being weaker at term. Strong FasL staining by cytotrophoblast cells in the distal parts of cell columns contrasted with unstained cytotrophoblast in the proximal part of columns. Distinct trophoblast subpopulations in partial hydatidiform mole also differentially expressed FasL with reduced FasL expression in proliferating syncytiotrophoblast. In contrast there was no differential FasL expression in complete hydatidiform mole, all trophoblast subpopulations strongly expressing FasL. Unlike the differential expression of FasL there were no differences in Fas expression by trophoblast populations in normal early or term placental tissues. Fas expression was reduced in villous cytotrophoblast at term. Differential expression of Fas by different trophoblast subpopulations was noted in partial and complete hydatidiform mole. In complete mole villous cytotrophoblast and syncytiotrophoblast stained strongly compared with proliferating trophoblast. Using TUNEL labelling apoptosis was rarely detected in placental trophoblast. Differential Fas and FasL expression by trophoblast subpopulations in normal and pathological pregnancy does not appear to be related to apoptosis of trophoblast.

Syphilitic placentitis: Demonstration ofTreponema pallidum by immunoperoxidase staining

We report a case of early congenital syphilis in which the placenta showed diffuse proliferative villitis and Treponema pallidum was identified by indirect immunoperoxidase stain in formalin-fixed paraffin-embedded placental tissue. This is the first report demonstrating T. pallidum in placental tissue using an immunohistochemical method.