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Platelet aggregation is a complicated process mediated by different signaling pathways. As the process is highly complex and apparently redundant, the relationships between these pathways are not yet fully known. The aim of this project was to study the interconnections among seven different aggregation pathways in a group of 53 generally healthy volunteers aged 20 to 66 years. Platelet aggregation was induced with thrombin receptor activating peptide 6 (TRAP), arachidonic acid (AA), platelet activating factor 16 (PAF), ADP, collagen, thromboxane A2 analogue U46619 or ristocetin (platelet agglutination) ex vivo in fasting blood samples according to standardized timetable protocol. Additionally, some samples were pre-treated with known clinically used antiplatelet drugs (vorapaxar, ticagrelor or acetylsalicylic acid (ASA)). Significant correlations among all used inducers were detected (Pearson correlation coefficients (rP): 0.3 to 0.85). Of all the triggers, AA showed to be the best predictor of the response to other inducers with rP ranging from 0.66 to 0.85. Interestingly, the antiplatelet response to ticagrelor strongly predicted the response to unrelated drug vorapaxar (rP = 0.71). Our results indicate that a response to one inducer can predict the response for other triggers or even to an antiplatelet drug. These data are useful for future testing but should be also confirmed in patients. [ABSTRACT FROM AUTHOR]

The process of platelet aggregation is often influenced by several factors including sex and age. A literature review confirmed the existence of sex-related differences in platelet aggregation. Although 68 out of 78 papers found such differences, there are still some controversies regarding these differences, which can be due to multiple factors (age, trigger, concomitant disease, sample handling, etc.). These outcomes are discussed in line with novel results obtained from a local study, in which blood samples from a total of 53 overall healthy women and men with ages ranging from 20 to 66 years were collected. Aggregation was induced with seven different triggers (ristocetin, thrombin receptor activating peptide 6 [TRAP-6], arachidonic acid [AA], platelet-activating factor 16 [PAF-16], ADP, collagen, or thromboxane A 2 analog U-46619) ex vivo. In addition, three FDA-approved antiplatelet drugs (vorapaxar, ticagrelor, or acetylsalicylic acid [ASA]) were also tested. In general, women had higher aggregation responses to some agonists (ADP, TRAP), as well as lower benefit from inhibitors (ASA, vorapaxar). The aggregatory responses to AA and TRAP decreased with age in both sexes, while responses to ADP, U-46619, and PAF were affected by age only in women. In conclusion, more studies are needed to decipher the biological importance of sex-related differences in platelet aggregation in part to enable personalized antiplatelet treatment. [ABSTRACT FROM AUTHOR]

The process of platelet aggregation is often conditioned by personal circumstances such as age, gender, lifestyle, and the presence of concomitant diseases. An additional factor is the resistance to current antiplatelet drugs developed by some patients, although the reason is not always obvious. In this work, we enrolled a total of 53 overall healthy women and men donors with ages ranging from 20 to 66 years for a cross-sectional study. Blood samples were taken, and aggregation was induced with a total of seven different compounds (ristocetin, thrombin receptor activating protein-6 [TRAP], arachidonic acid [AA], platelet activating factor-16 [PAF], ADP, collagen, or thromboxane A2 analogue U46619) ex vivo. In addition, some samples were pretreated with clinically used antiplatelet drugs (vorapaxar, ticagrelor, or acetylsalicylic acid [ASA]). Our results showed a pattern in which increasing age decreased the aggregatory responses to AA and TRAP in both genders, whereas responses to ADP, U-46619, and PAF were affected by age only in women. In addition, women had stronger responses to some aggregation inducers (ADP, TRAP), as well as lower benefit from antiplatelet drugs (ASA, vorapaxar). Physiological levels of blood lipids and glucose, as well as body mass index, had mostly no effect on platelet aggregation in this study. On the contrary, several strong positive correlations between different aggregation triggers were observed. The different responses in women, in relation to age, are of note for future studies. [ABSTRACT FROM AUTHOR]