PB0888 - The effect of polyphenols on platelet procoagulant activity and fibrin clot structure

Background: Plant-derived compounds (polyphenols) have been shown to impact glycaemic response, oxidative stress, and platelet-neutrophil aggregates. Nevertheless, their effect on clot structure and platelet procoagulant response is unknown.

Aims: To investigate the effect of polyphenols on clot structure and platelet procoagulant activity.

Methods: Four polyphenols (resveratrol, hesperetin, epigallocatechin gallate (EGCG) and quercetin) were selected for initial analysis based on their reported effects on glycaemic response in vitro. Procoagulant platelets (PP; annexin-V) and fibrin fiber density (AlexaFluor 488 fibrinogen) were analysed in platelet-rich plasma (PRP) clots by laser scanning confocal microscopy in normo- (5 mM glucose; 20 mins incubation) and hyperglycaemic (25 mM glucose; 20 mins incubation) conditions. Platelets isolated from healthy volunteers (in isolation buffer containing 5 or 25mM glucose) were used to determine platelet ROS following exposure to polyphenols (20µM; 1 hr incubation) using commercially available DCFDA cellular ROS assay kit. Platelet mitochondria density following exposure to polyphenols (20µM; 1 hr incubation) was measured in healthy volunteer platelet lysates using a citrate synthase assay.

Results: Procoagulant platelet number was increased in hyperglycaemic conditions. Resveratrol treatment decreased procoagulant platelet number in normo- (22±3 and 39±7 for resveratrol treated and control, respectively; p< 0.05) and hyperglycaemic conditions (32±5 and 48±5 for resveratrol treated and control, respectively; p< 0.05). No significant effects on fibrin fiber clot density were observed following resveratrol treatment. Resveratrol, quercetin and EGCG reduced platelet ROS in normo- (46±15%, 56±9% and 43±15%, respectively) and hyperglycaemic conditions (67±9%, 68±7% and 56±11%, respectively). Quercetin and EGCG both decreased platelet mitochondrial density by 30% (±12 and 3%, respectively) compared to control.

Conclusion(s): Our data show that polyphenols modulate platelet procoagulant activity and bioenergetics. Furthermore, our results indicate that specific polyphenolic compounds may counteract hyperglycaemia-induced increases in platelet procoagulant activity and cellular ROS. These findings may have important implications for treatments aimed at reducing thromboinflammation.