Whole blood platelet aggregation failed to detect differences between preeclampsia and normal pregnancy

Platelets in Fetal Growth Restriction: Role of Reactive Oxygen Species, Oxygen Metabolism, and Aggregation

Fetal growth restriction (FGR) is mainly caused by failure of the uteroplacental unit. The exact pathogenesis remains unclear. The cause is thought to be related to abnormal platelet activation, which may result in microthrombus formation in the small vessels of the placenta. Reactive oxygen species (ROS) may initiate the pathological process of platelet activation. This study aimed to evaluate selected platelet parameters in pregnancy complicated by FGR and relate them to the severity of hemodynamic abnormalities. A total of 135 women (pregnant with FGR, with an uncomplicated pregnancy, and non-pregnant) were enrolled to study different platelet parameters: count (PLT), mean volume (MPV), ROS levels, intracellular oxygen level, oxygen consumption, and aggregation indices. No abnormalities in PLT and MPV were found in the FGR group, although it revealed increased ROS levels in platelets, lower platelet oxygen consumption, and intraplatelet deprivation. Aggregation parameters were similar as in uncomplicated pregnancy. No significant relationships were observed between hemodynamic abnormalities and the studied parameters. Platelets in pregnancies complicated by FGR may reveal an impaired oxidative metabolism, which may, in turn, lead to oxidative stress and, consequently, to an impaired platelet function. This study adds to the understanding of the role of platelets in the etiology of FGR.

Platelet function in preeclampsia - a systematic review and meta-analysis

Preeclampsia is a serious pregnancy-related complication. Platelets are potentially important in the pathogenesis of preeclampsia, and platelet function analyses may prove as sensitive preeclampsia biomarkers. This study aimed to systematically review and summarise the literature on platelet function markers in preeclampsia. This systematic review was conducted according to PRISMA and registered in PROSPERO. Relevant studies were identified through PubMed and Embase on 15/08/17. As platelet function markers platelet activation, platelet aggregation and platelet adhesion markers were included. If possible, relevant data were extracted for each marker to perform a meta-analysis of the mean difference between women with and without preeclampsia. All 69 included articles underwent quality rating. Some platelet activation markers, especially p-selectin and mean platelet volume (MPV), were significantly increased comparing the two groups of women, while others were not. The meta-analysis demonstrated that, overall, women with preeclampsia had significantly higher MPV than in women without preeclampsia. No significant difference was found regarding platelet aggreg`ation comparing the two groups. Platelet adhesion was investigated in noneof the included studies. In conclusion, further studies are warranted to investigate platelet activation markers future role as predictive markers in preeclampsia. MPV is suggested as the most promising biomarker for evaluating platelet function in preeclampsia.

Platelet behaviour on von Willebrand Factor changes in pregnancy: Consequences of haemodilution and intrinsic changes in platelet function

Platelet function in pregnancy is poorly understood. Previous studies of platelet function in pregnancy have used non-physiological assays of platelet function with conflicting results. This study using a physiological assay of platelet function investigated platelet interactions with von Willebrand Factor (VWF) in blood from healthy pregnant women and healthy non-pregnant controls. Blood samples (200 µl) from third-trimester pregnancies (n = 21) and non-pregnant controls (n = 21) were perfused through custom-made parallel-plate flow chambers coated with VWF under arterial shear (1,500 s⁻¹). Multi-parameter measurements of platelet interactions with the immobilized VWF surface were recorded by digital-image microscopy and analysed using custom-designed platelet-tracking software. Platelet interactions with VWF decreased in healthy third-trimester pregnant participants relative to controls. This effect is most likely due to haemodilution which occurs physiologically during pregnancy. Interestingly, platelets in blood from pregnant participants translocated more slowly on VWF under arterial-shear conditions. These decreases in platelet translocation speed were independent of haemodilution, suggesting intrinsic changes in platelet function with pregnancy.

Polymorphisms of Platelet Glycoprotein Receptors and Cell Adhesion Molecules in Fetuses with Fetal Growth Restriction and Their Mothers As Detected with Pyrosequencing

BACKGROUND

Vascular thrombotic tendency may lead to fetal growth restriction (FGR). Altered platelet function and genetic heterogeneity may play a role in this procedure. We investigated whether maternal or fetal genotypic frequencies of genes polymorphisms for certain platelet receptor and cell adhesion molecules are altered in FGR.

MATERIALS AND METHODS

We compared the maternal and fetal genotypic frequencies of single nucleotide polymorphisms (SNPs) in four genes coding for platelet receptors and cell adhesion molecules [integrin alpha subunit 2 (ITGA2)C807T, integrin subunit beta 3(ITGB3) T1565C, platelet cell adhesion protein 1 (PECAM1) CTG-GTG and selectin P(SELP)A/C]. A total of 32 fetuses with fetal growth restriction and their mothers were matched with 18 normal controls. Using maternal venous blood and umbilical cord blood samples, nucleotide sequences were determined from pyrograms. Genotypic frequencies were calculated and analyzed using appropriate tests and logistic regression.

RESULTS

There was no statistical difference in the proportion of heterozygotes or homozygotes for any of the genotypic frequencies between FGR and control groups in mothers or fetuses.

CONCLUSION

Our study demonstrated no association of maternal or fetal ITGA2 C807T SNP, ITGB3 T1565C SNP, PECAM1 CTG - GTG and SELP A/C polymorphisms with FGR.