Erythropoietin and Platelet Activation Markers

Introduction: Erythropoietin (EPO) enhances formation of red blood cells and also affects thrombopoiesis and platelet function. We hypothesized that the effect of erythropoietin may be reflected by changes in thromboxane B2 (TXB2) and endothelial cell function.

Methods: Six male and six female subjects received recombinant human epoetin alpha (Erypo®) intravenously (300 Units per kg). Biomarker levels were assessed at baseline and 4, 24, 48 and 72 hours after administration.

Results: Epoetin alpha increased TXB2 levels, which reached significance at 48h (2.5- fold increase: 6.6±5ng/mL vs. 15±9ng/mL; p=0.044) and remained at that level at 72h. In line, epoetin alpha increased E-selectin levels by 25% already at 24h (39±21ng/ml vs. 49±26ng/ml; p<0.001) and stayed at this level until 72h (p<0.001). The raise in platelet activation markers corresponded with a 2-fold increase in reticulocyte count (81±17G/L vs. 43±10G/L; p<0.001) and a 9% increase in platelet count at 72h (224±45G/L vs. 244±52G/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±24ng/mL and 28±10ng/mL; p=0.025 and 30±5ng/mL vs. 16±5ng/mL; p=0.002, respectively).

Conclusion: Epoetin alpha increases levels of platelet activation markers. Further studies are needed to investigate whether measurement of TXB2 or E-selectin levels might be useful for estimation of thromboembolic risk during EPO-therapy.

Inclusion criteria

• Healthy male and female volunteers.
• Age between 18-40 years.
• Body mass index 17-27.
• Normal haemoglobin levels (Hb males 13.5-18g/dL, females 12-16g/dL).
• Reticulocyte count within reference values (32-110G/L).
• S-Iron within reference values (males 60-150µg/dl, females 40-150µg/dL).
• Serum ferritin within reference values (females 10-140µg/L, males 20-280µg/L).
• CRP within reference values (<1,0mg/dL).
• Signed informed consent.
• Normal findings in medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant for this study.
• Woman of child bearing potential must agree to practice effective barrier methods for birth control.

Exclusion criteria

• Smoking.
• Regular use of medication and food supplements containing iron.
• Abuse of alcoholic beverages and drugs.
• Participation in a clinical trial in the 3 weeks preceding the study.
• Foreseen inability to attend to scheduled study visits.
• Deficiency in folate (<3.4nmol/L) or vitamin B12 (<118pmol/L) (reevaluation after supplementation is allowed).
• Evidence of hypertension, pathologic hyperglycemia, hyperlipidemia. AST and/or ALAT > 3xULN (AST males > 105U/L, females >93U/; ALAT males > 135U/L, females >102U/L).
• Symptoms of a clinically relevant illness during 3 weeks prior the first study day.
• History or presence of gastrointestinal, liver or kidney disease, or other conditions known to interfere with distribution, metabolism or excretion of erythropoietin.
• Blood donation during the previous 3 weeks prior to the first study day.
• History of hypersensitivity erythropoietin.
• Pregnancy or lactation period.
• Any medical condition that, in the opinion of the investigator, would interfere with safety of the subject or interference of the objectives of the study.