Platelet aggregation in healthy women during normal pregnancy - a longitudinal study

The Association Between the Maternal Pre-pregnancy Platelet Count and Fecundability in Mainland China: A Population-based Cohort Study

BACKGROUND

Currently, awareness about platelet count (PC) and its consequences for perinatal outcome have increased, but there is little reliable evidence on fecundability.

METHODS

Based on the National Free Pre-conception Check-up Projects supported by the Chinese government, 5,524,886 couples met the inclusion criteria and were included in this cohort study. Cox regression models were adopted to estimate fecundability ratios (FRs) and their 95% confidence intervals (CIs) for pre-pregnancy PC quintiles. Restricted cubic splines were used to flexibly model and visualize the relationship of PC with FRs. Microsoft SQL server and R software were used for data management and analysis.

RESULTS

The median of pre-pregnancy PC among women was 221.00 × 109/L. The first (<177.00 × 109/L) and second quintile (177.00-207.99 × 109/L) of PC showed slightly increased fecundability (Q1: adjusted FR 1.05; 95% CI, 1.04-1.06; Q2: adjusted FR 1.04; 95% CI, 1.03-1.05), while higher quintals (Q4: 236.00-271.99 × 109/L; Q5: ≥272.00 × 109/L) were related to reduction of fecundability, when compared with the third quintile of PC (208.00-235.99 × 109/L) (Q4: adjusted FR 0.96; 95% CI, 0.95-0.97; Q5: adjusted FR 0.88; 95% CI, 0.87-0.89). In the first quintiles (<177.00 × 109/L), only 20.93% women had PC below 129.94 × 109/L. An inverse-U-shaped association was consistently observed among women such that the lower PC within the normal range (<118.03 × 109/L) and higher PC (>223.06 × 109/L) were associated with the risk of reduced female fecundability (P for non-linearity < 0.01).

CONCLUSION

PC is associated with female fecundability. Further classification of PC levels may deepen our understanding of the early warnings and significance of female fecundability.

Gestational diabetes mellitus is associated with in vivo platelet activation and platelet hyperreactivity

BACKGROUND

Gestational diabetes mellitus is associated with obstetrical and long-term cardiovascular complications. Although platelet hyperresponsiveness in type-2 diabetes mellitus has been well characterized and has been shown to play a crucial role in cardiovascular complications, this aspect has been little studied in gestational diabetes mellitus.

OBJECTIVE

We aimed to evaluate platelet reactivity, in vivo platelet activation, and endothelial function in gestational diabetes mellitus in comparison with normal pregnancy.

STUDY DESIGN

This was a prospective, case-control study of 23 women with gestational diabetes mellitus and 23 healthy pregnant women who were studied at 26 to 28 and 34 to 36 weeks of gestation and at 8 weeks postpartum. Platelet reactivity and in vivo platelet activation, including light transmission aggregometry, PFA-100, platelet activation antigen expression, platelet adhesion under flow, platelet nitric oxide and reactive oxygen species production, and endothelial dysfunction markers, were assessed.

RESULTS

The study of platelet function showed a condition of platelet hyperreactivity in cases with gestational diabetes mellitus when compared with healthy pregnant women at enrollment, which was further enhanced at the end of pregnancy and tended to decrease 2 months after delivery, although it still remained higher in gestational diabetes mellitus. In vivo platelet activation was also evident in gestational diabetes mellitus, especially at the end of pregnancy, in part persisting up to 8 weeks after delivery. Finally, women with gestational diabetes mellitus showed defective platelet nitric oxide production and endothelial dysfunction when compared with healthy pregnancies.

CONCLUSION

Our data showed that gestational diabetes mellitus generates a condition of platelet hyperreactivity that in part persists up to 2 months after delivery. Impaired platelet sensitivity to nitric oxide and reduced platelet and endothelial nitric oxide production may contribute to the platelet hyperreactivity condition. Platelet hyperreactivity may play a role in the long-term cardiovascular complications of gestational diabetes mellitus women.

Pregnancy as a susceptible state for thrombotic microangiopathies

Pregnancy and the postpartum period represent phases of heightened vulnerability to thrombotic microangiopathies (TMAs), as evidenced by distinct patterns of pregnancy-specific TMAs (e.g., preeclampsia, HELLP syndrome), as well as a higher incidence of nonspecific TMAs, such as thrombotic thrombocytopenic purpura or hemolytic uremic syndrome, during pregnancy. Significant strides have been taken in understanding the underlying mechanisms of these disorders in the past 40 years. This progress has involved the identification of pivotal factors contributing to TMAs, such as the complement system, ADAMTS13, and the soluble VEGF receptor Flt1. Regardless of the specific causal factor (which is not generally unique in relation to the usual multifactorial origin of TMAs), the endothelial cell stands as a central player in the pathophysiology of TMAs. Pregnancy has a major impact on the physiology of the endothelium. Besides to the development of placenta and its vascular consequences, pregnancy modifies the characteristics of the women's microvascular endothelium and tends to render it more prone to thrombosis. This review aims to delineate the distinct features of pregnancy-related TMAs and explore the contributing mechanisms that lead to this increased susceptibility, particularly influenced by the "gravid endothelium." Furthermore, we will discuss the potential contribution of histopathological studies in facilitating the etiological diagnosis of pregnancy-related TMAs.

Overexpression of facilitative glucose transporter-3 and membrane procoagulation in maternal platelets of preeclamptic pregnancy

BACKGROUND

Preeclampsia (PE) is a hypertensive disorder during pregnancy that results in significant adverse maternal and neonatal outcomes. Platelet activation is present in PE and contributes to the thrombo-hemorrhagic states of the disorder. However, the mechanisms that initiate and/or sustain platelet activation in PE are ill-defined.

OBJECTIVES

We aimed to characterise this mechanism and the procoagulant potentials of platelets in PE.

METHODS

In this quantitative observational study, we analyzed platelet procoagulant membrane dynamics in patients with PE (n = 21) compared with age-matched normotensive pregnancies (n = 20), gestational hypertension (n = 10), and non-pregnant female controls (n = 19). We analyzed fluorescently labeled indicators of platelet activation, bioenergetics, and procoagulation (phosphatidylserine exposure and thrombin generation), coupled with high-resolution imaging and thrombelastography. We then validated our findings using flow cytometry, immunoassays, classical pharmacology, and convolutional neural network analysis.

RESULTS

PE platelets showed significant ultra-structural remodeling, are more extensively preactivated than in healthy pregnancies and can circulate as microaggregates. Preactivated platelets of PE externalized phosphatidylserine and thrombin formed on the platelet membranes. Platelets' expression of facilitative glucose transporter-1 increased in all pregnant groups. However, PE platelets additionally overexpress glucose transporter-3 to enhance glucose uptake and sustain activation and secretion events. Although preeclampsia platelets exposed to subendothelial collagen showed incremental activation, the absolute hemostatic response to collagen was diminished, and likely contributed to greater blood loss perioperatively.

CONCLUSIONS

We revealed 2 bioenergetic mediators in the mechanism of sustained platelet procoagulation in preeclampsia. Although glucose transporter-1 and glucose transporter-3 remain elusive antiprocoagulant targets, they may be sensitive monitors of PE onset and progression.

Platelets and endothelial dysfunction in gestational diabetes mellitus

The prevalence of gestational diabetes mellitus (GDM) has increased in recent years, along with the higher prevalence of obesity in women of reproductive age. GDM is a pathology associated with vascular dysfunction in the fetoplacental unit. GDM-associated endothelial dysfunction alters the transfer of nutrients to the foetus affecting newborns and pregnant women. Various mechanisms for this vascular dysfunction have been proposed, of which the most studied are metabolic alterations of the vascular endothelium. However, different cell types are involved in GDM-associated endothelial dysfunction, including platelets. Platelets are small, enucleated cell fragments that actively take part in blood haemostasis and thrombus formation. Thus, they play crucial roles in pathologies coursing with endothelial dysfunction, such as atherosclerosis, cardiovascular diseases, and diabetes mellitus. Nevertheless, platelet function in GDM is understudied. Several reports show a potential relationship between platelet volume and mass with GDM; however, platelet roles and signaling mechanisms in GDM-associated endothelial dysfunction are unclear. This review summarizes the reported findings and proposes a link among altered amount, volume, mass, reactivity, and function of platelets and placenta development, resulting in fetoplacental vascular dysfunction in GDM.

Platelet aggregation in normal pregnancy

It was recently shown that abnormal platelet aggregation (PA) had played a critical role in some adverse pregnancies. Till now reference range for PA in normal pregnancy has not been determined. Furthermore, few study has been conducted to explore the factors related to PA. Our study was performed to assess the reference range of PA in normal pregnancy (150 participants in the second trimester), and to determine whether it differs from that of the controls (38 nonpregnant participants). In addition, this study explored the factors related to PA. The results showed that PA was significantly higher in normal pregnancy than that in the controls (84.40% vs. 80.7%, respectively, P = 0.013). The reference interval for PA in normal pregnancy was 74.75%-94.77%. Hemoglobin (Hb), platelet counts (PLT) and albumin (Alb) were significant lower in normal pregnancy than those in the control group. Moreover, it was found that PA was positively correlated with PLT (r = 0.263, P < 0.001), and negatively correlated with platelet distribution width (PDW) (r = -0.342, P < 0.001) and mean platelet volume (r = -0.296, P < 0.001). Linear correlations between PA and Alb, PDW were proved by linear regression model (LRM). In conclusion, PA was enhanced in normal pregnancy, and Alb and PDW might be the possible contributing factors to PA.

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.

A new decade awaits sticky platelet syndrome: where are we now, how do we manage and what are the complications?

INTRODUCTION

Sticky platelet syndrome is a less known platelet function disorder with a familiar occurrence and likely genetic background. Clinically, it is characterized by an increased risk of venous and arterial thromboembolic events and obstetric placenta-mediated complications. The increased aggregation after low-dose ADP and/or epinephrine is its distinctive laboratory feature. Though described for almost 40 years, several issues regarding its etiology, involved pathomechanisms, genetic background, optimal diagnostic and treatment approach remain controversial.

AREAS COVERED

The work aims to summarize published studies, the actual definition of the syndrome, and point out its drawbacks. A literature search on Medline, Embase, and archives from EHA congresses was performed (terms: 'sticky platelet syndrome' - 'platelet hyperreactivity' - 'platelet hyperaggregability'). The authors added in their unpublished data. The introductory overview of the present understanding is followed by the discussion of the pathophysiologic, diagnostic, and therapeutic problems.

EXPERT OPINION

Despite the growing evidence provided by case reports and series, the lack of robust studies limits the decision-making on diagnostics and management. The diagnostic issues, particularly the standardization of light transmission aggregometry, represent the crucial problem for the broader acceptance of the syndrome.

Arachidonic acid-induced platelet aggregation and acetylsalicylic acid treatment during pregnancy in women with recurrent miscarriage, a post hoc study

In this post hoc study, arachidonic acid (AA)-induced platelet aggregation during pregnancy with and without acetylsalicylic acid (ASA) treatment was studied in 323 women with unexplained recurrent first-trimester miscarriage and in 59 healthy women with normal pregnancies. All women had normal AA-induced platelet aggregation in the non-pregnant state. Women with recurrent miscarriage were treated with 75 mg ASA or placebo daily. AA-induced platelet aggregation was measured with multiple electrode impedance aggregometry and presented in units (U), where 1 U = 10 aggregation units x minutes. There were no significant differences in platelet aggregation between placebo-treated women with recurrent miscarriage and healthy women. The mean differences were-0.7 (95%CI; -7.0; 5.6) U in the non-pregnant state, 3.8 (95%CI; -4.6; 12.2) U during the late first trimester and 1.7 (95%CI; -6.7; 10.3) U and 4.1 (95%CI; -3.9; 12.0) U during the early and late third trimester, respectively. ASA reduced platelet aggregation by median -84.0% (Q1; Q3; -89.8; -76.3), -79.9% (-84.7; -69.2) and -75.7% (-83.5; -49.5), respectively, during pregnancy. The degree of inhibition by ASA decreased during the third trimester (p < .0001). There were two (1.9%) complete non-responders to ASA and 32.1% with a partial response. The rate of subsequent miscarriage was not affected by ASA, which did not seem to influence the rate of early miscarriage if treatment was initiated when a viable pregnancy was detectable by ultrasound.

Study of the effect of selective inhibitor of Arginase II KUD 975 and of low doses of Acetylsalicylic acid on the functional parameters of the cardiovascular system In experimental preeclampsia

Introduction: Over the past decade, preeclampsia has been the subject of an increased attention, as this complication is the most common cause of maternal mortality, triggering every third case of obstetric morbidity and taking lives of up to 50.000 young women worldwide each year. Despite a large number of ongoing studies, no clear algorithm for monitoring pregnant women with this pathology has been developed yet.

Materials and methods: The study was conducted on 220 female Wistar rats weighing 250–300 g. In the experiment, ADMA-like preeclampsia model was used.

Results and discussion: The introduction of L-NAME to the animals from the 14th till the 20th day of pregnancy causes the following disturbances: a rise in systolic and diastolic blood pressure in 1.4 and 1.5 times, an increase in proteinuria in 3.3 times and an increase in the content of fluid in the greater omentum from 44.39 ± 1.62% to 55.02 ± 1.74%, all of which correspond to the disorders in pregnant women in case of preeclampsia.

The use of the selective inhibitor of arginase II KUD 975 (3mg/kg/day) in combination with acetylsalicylic acid (10mg/kg/day) leads to a pronounced correction in the emerging changes: a decrease in systolic and diastolic blood pressure in 1.2 and 1.3 times, a decrease in proteinuria in 1.9 times and a decrease in the fluid content in the greater omentum.

Conclusion: Selective inhibitor of arginase II KUD 975 and small doses of acetylsalicylic acid have a pronounced positive effect in the correction of morphofunctional disorders in animals with ADMA-like preeclampsia.

L-NAME-induced Preeclampsia: correction of functional disorders of the hemostasis system with Resveratrol and Nicorandil

Introduction. Preeclampsia is a formidable disease of the second half of pregnancy, leading to severe complications, including disability and even death. Many authors have recognized the correlation between the severity of preeclampsia and the degree of disturbances in the hemostasis system. In this regard, the objective of this study was to assess inhibition of platelet aggregation and the possibility of its correction with resverаtrol and nicorandil.

Materials and methods. The study was performed on 250 mature white Wistar female rats weighing 250–300 g. The platelet aggregation induced by ADP, collagen, ristomycin, adrenaline was determined, as well as PTT, TT, aPTT, fibrinogen, and the clotting time.

Results and discussion. Introduction of resverаtrol and nicorandil resulted in a decrease in thrombocyte aggregation capacity from 53.8 ± 2.60% to 22.1 ± 1.25% and 37.1 ± 1.79%, respectively, when using ADP as an inducer. The clotting time was from 841 ± 42 s up to 1135 ± 33 s and 1034 ± 26 s, respectively. In addition, there was an increase in temporal parameters of plasma-coagulation hemostasis and a decrease in plasma fibrinogen content. The use of glibenclamide resulted in partial cancellation of the positive effects of resverаtrol and nicorandil, with an increase in platelet aggregation to 28.9 ± 1.8% and 43.9 ± 1.2% when using ADP as an inducer and a decrease in the thrombosis time to 988 ± 26 s and 950 ± 22 s, respectively.

Conclusion. In animals with experimental preeclampsia, there were disturbances in the hemostasis system, comparable to those in the clinical situation. The use of resverаtrol and nicorandil leads to a pronounced correction of hemostasis parameters. The positive effects of the studied pharmacological agents are mediated by several mechanisms, including K+ATP channels.