Data from a microdosed recombinant human erythropoietin administration study applying the new biotinylated clone AE7A5 antibody and a further optimized sarcosyl polyacrylamide gel electrophoresis protocol.

Erythropoietin (EPO) is a hormone, which stimulates the production of red blood cells. Due to its performance-enhancing effect, it is prohibited by the World Anti-Doping Agency (WADA). In order to reduce the detection window of EPO doping, athletes have been applying low doses of recombinant EPO (e.g., <10 IU/kg body weight, daily or every second day) instead of larger doses twice or more per week (e.g., 30 IU/kg). Microdoses of Retacrit (epoetin zeta), an EPO biosimilar, were administered intravenously and subcutaneously to human males and females. Urine and serum samples were collected and analysed applying the new biotinylated clone AE7A5 EPO antibody and a further optimized sarcosyl polyacrylamide gel electrophoresis (SAR-PAGE) protocol. With the improved protocol, microdosed Retacrit (7.5 IU/kg body weight [BW]) was detectable for at least 52 h after intravenous administration. Detection windows were approximately the same for serum and urine and doubled after subcutaneous administration (~104 h). Previous studies applying different electrophoretic techniques and the not further optimized SAR-PAGE protocol revealed considerably shorter detection windows for recombinant human erythropoietin (rhEPO) microdoses. Because the new biotinylated antibody performed significantly more sensitive than the nonbiotinylated version, the new protocol will improve the sensitivity and hence detectability of recombinant EPO in doping control.

Defending Dynepo detection.

Doping analysis as the detection of prohibited substances in an athlete's bodily specimen is not solely a scientific task; anti-doping scientists are challenged by the athlete's experts and have to defend their results in front of arbitration panels such as the Court of Arbitration in Sports (CAS). Compliance with the internationally accepted standards issued by the World Anti-Doping Agency (WADA) is commonly the main aspect to prove and demonstrate. Taking the example of four cases of doping with Epoetin delta (Dynepo) in endurance disciplines like marathon, triathlon, and cycling, the challenges and experiences in court and the argumentation lines of the defence experts are discussed. In all cases, doping with Epoetin delta was detected by two methods: isoelectric focusing (IEF) and SDS-PAGE. Epoetin delta is known to be produced in a human fibrosoma cell line. The slightly more abundant bands alpha and beta result in a short detection window using IEF analysis alone. With the additional complementary information obtained by SDS-PAGE analysis, data interpretation and defence in court is facilitated.

The interference of heparin on IEF-PAGE of erythropoietins.

Because of the risk of suffering a stroke or heart attack, some athletes and their medical supervisors admitted having used anticoagulants (e.g. acetylsalicylic acid) in combination with doping with recombinant erythropoietins (rhEPO). Heparin is one of the oldest and cheapest anticoagulants. The anticoagulative effect of heparin is a result of the binding of heparin to the plasma protein antithrombin III and the subsequent inactivation of blood clotting factors (e.g. factor IIa, IXa, Xa, XIa, XIIa). Heparin-a polyanion-is known to interact with carrier ampholytes used in IEF-PAGE. Two different types of heparin pharmaceuticals are used for medical purposes: unfractionated heparins (UFH) and low molecular weight heparins (LMWH). Their influence on IEF- and SDS-PAGE was investigated. Only UFH had a profound impact on IEF-PAGE, leading to excessive smearing or complete abolishment of the EPO IEF-profile and shifting of acidic EPO-isoforms in the endogenous region of the gel. No such effect was observable for SDS-PAGE. Remedies include immunoaffinity purification of EPO before IEF-PAGE or the treatment of the urinary retentate with solid urea. A combined usage of IEF- and SDS-PAGE is recommended for confirming the presence of rhEPO in urine and for further analysis of smearing (and therefore suspicious) samples. This two-method approach is already in accordance with the technical document on EPO-analysis (TD2009EPO) of the World Anti-Doping Agency (WADA).