The effect of erythropoietin on platelet and endothelial activation markers: a prospective trial in healthy volunteers.

Erythropoietin (EPO) enhances formation of red blood cells and also affects thrombopoiesis and platelet function. We hypothesized that the effect of EPO may be reflected by changes in thromboxane B2 (TXB2) and endothelial cell function. Six male and six female subjects received recombinant human epoetin alpha (Erypo®) intravenously (300 U/kg). Biomarker levels were assessed at baseline and 4, 24, 48 and 72 hours after infusion. Epoetin alpha increased TXB2 levels by 140%, which reached significance at 48 hours (6.6 ± 5 ng/ml vs. 15 ± 9 ng/ml; p = 0.044) and remained at that level at 72 hours. In line, epoetin alpha increased E-selectin levels by 25% already at 24 hours (39 ± 21 ng/ml vs. 49 ± 26 ng/ml; p < 0.001) which stayed at this level until 72 hours (p < 0.001). The raise in platelet activation markers corresponded to an 88% increase in reticulocyte count (43 ± 10 × 10(9)/l vs. 81 ± 17 × 10(9)/l; p < 0.001) and a 9% increase in platelet count at 72 hours (224 ± 45 × 10(9)/l vs. 244 ± 52 × 10(9)/l; p = 0.005). Thrombomodulin and von Willebrand factor concentrations were not significantly altered by epoetin alpha. Interestingly, gender differences in the baseline levels of E-selectin and thrombomodulin were observed. E-selectin and thrombomodulin levels were doubled in men compared to women (51 ± 24 and 28 ± 10 ng/ml; p = 0.025 and 30 ± 5 ng/ml vs. 16 ± 5 ng/ml; p = 0.002, respectively). EPO increases TXB2 serum levels and soluble E-selectin. Further studies are needed to investigate whether these markers might be useful for estimation of thromboembolic risk during EPO-therapy and whether inhibition of thromboxane formation may lower thrombotic complications during EPO treatment: NCT01392612.