Impact of high dose vitamin C on platelet function

Abstract

AIMTo examine the effect of high doses of vitamin C (VitC) on ex vivo human platelets (PLTs).METHODSPlatelet concentrates collected for therapeutic or prophylactic transfusions were exposed to: (1) normal saline (control); (2) 0.3 mmol/L VitC (Lo VitC); or (3) 3 mmol/L VitC (Hi VitC, final concentrations) and stored appropriately. The VitC additive was preservative-free buffered ascorbic acid in water, pH 5.5 to 7.0, adjusted with sodium bicarbonate and sodium hydroxide. The doses of VitC used here correspond to plasma VitC levels reported in recently completed clinical trials. Prior to supplementation, a baseline sample was collected for analysis. PLTs were sampled again on days 2, 5 and 8 and assayed for changes in PLT function by: Thromboelastography (TEG), for changes in viscoelastic properties; aggregometry, for PLT aggregation and adenosine triphosphate (ATP) secretion in response to collagen or adenosine diphosphate (ADP); and flow cytometry, for changes in expression of CD-31, CD41a, CD62p and CD63. In addition, PLT intracellular VitC content was measured using a fluorimetric assay for ascorbic acid and PLT poor plasma was used for plasma coagulation tests [prothrombin time (PT), partial thrombplastin time (PTT), functional fibrinogen] and Lipidomics analysis (UPLC ESI-MS/MS).RESULTSVitC supplementation significantly increased PLTs intracellular ascorbic acid levels from 1.2 mmol/L at baseline to 3.2 mmol/L (Lo VitC) and 15.7 mmol/L (Hi VitC, P < 0.05). VitC supplementation did not significantly change PT and PTT values, or functional fibrinogen levels over the 8 d exposure period (P > 0.05). PLT function assayed by TEG, aggregometry and flow cytometry was not significantly altered by Lo or Hi VitC for up to 5 d. However, PLTs exposed to 3 mmol/L VitC for 8 d demonstrated significantly increased R and K times by TEG and a decrease in the α-angle (P < 0.05). There was also a fall of 20 mm in maximum amplitude associated with the Hi VitC compared to both baseline and day 8 saline controls. Platelet aggregation studies, showed uniform declines in collagen and ADP-induced platelet aggregations over the 8-d study period in all three groups (P > 0.05). Collagen and ADP-induced ATP secretion was also not different between the three groups (P > 0.05). Finally, VitC at the higher dose (3 mmol/L) also induced the release of several eicosanoids including thromboxane B2 and prostaglandin E2, as well as products of arachidonic acid metabolism via the lipoxygenases pathway such as 11-/12-/15-hydroxyicosatetraenoic acid (P < 0.05).CONCLUSIONAlterations in PLT function by exposure to 3 mmol/L VitC for 8 d suggest that caution should be exerted with prolonged use of intravenous high dose VitC.

The Emerging Role of Vitamin C as a Treatment for Sepsis

“…Alters platelet oxidative states by inhibiting CD40 ligand expression on platelet surfaces [109]. Prolonged platelet exposure to HDIVC increases Thromboxane-B2 and Prostagladin-E2 levels [110,111]. HDIVC stabilizes ADAMTS13 levels and its von-Willebrand factor cleavage activity [112].…”

Reductive Stress in Inflammation-Associated Diseases and the Pro-Oxidant Effect of Antioxidant Agents

“…The ascorbic activity of vitamin C lies in its role as an essential cofactor in hydroxylation reactions involved in the biosynthesis of stable cross-linked collagen. Ascorbic acid scavenges O 2 − , H 2 O 2 , OH•, HOCl, and aqueous peroxyl radicals [ 159 ]. Ascorbic acid undergoes two-electron oxidation to dehydroascorbic acid, with intermediate formation of the relatively unreactive ascorbyl radical during its antioxidant action [ 160 ].…”

Investigation of the Opposite Capacities of Erythropoietin and U-74389G on Platelet Crit Levels

“…Patients in the intervention group were achieving 9.85-fold more frequently the platelet count of ≥50,000/mm3 than control group (P = 0.0019) at the end of 48h. Mohammed et al [14] significantly increased PLTs intracellular ascorbic acid levels by 2.66-fold (Lo Vitamin C) and by 13.08-fold (Hi Vitamin C, P<0.05) after Vitamin C supplementation. Also, Vitamin C at the higher dose (3mmol/L) also induced the release of several eicosanoids including thromboxane B 2 and prostaglandin E 2 , as well as products of arachidonic acid metabolism via the lipoxygenases pathway such as 11-/12-/15-hydroxyicosatetraenoic acid (P <0.05).…”