Application of DNA-based forensic analysis for the detection of homologous transfusion of whole blood and of red blood cell concentrates in doping control

Homologous blood transfusion and doping: Where are we now?

Homologous blood transfusion (HBT) is used for doping in endurance sports since the 1960s. The blood comes from a compatible donor, that is, someone with a compatible ABO and rhesus blood group. Despite been prohibited by the IOC in 1985, no detection method was available until 2003. Then came the idea to use red blood cells (RBC) minor blood groups antigens that constitute an "identity" card of someone's RBC to detect the presence of a second RBC population. The method validated for doping control samples uses flow cytometry after incubation of isolated RBC with eight to 12 primary antibodies against specific minor blood groups antigens. The presence of double populations of RBC is revealed by a major and a minor peak in a fluorescence histogram. The sensitivity was estimated sufficient to detect HBT for a few weeks. Despite the complexity and cost of the method, right after its application in 2004, several cases of HBT were identified but the number of cases dropped rapidly over the years. In the 2010s, other ways to detect HBT were developed and evaluated: indirect detection using the Athlete Biological Passport approach, and a few years later forensic DNA analysis to establish the presence of two different DNA in a blood sample after HBT. Despite the high specificity of the latter, the sensitivity was recently questioned in vivo. Nowadays, the flow cytometry method remains the method of choice for HBT detection and recent investigations helped to simplify the method and increase its specificity and sensitivity.

A SNP-based genotyping strategy to detect the abuse of homologous blood transfusion from dried blood spots

We performed genotyping analysis of human biallelic polymorphisms (single nucleotide polymorphisms) for the detection of homologous blood transfusion in sports doping. DNA was extracted from dried blood spots and quantified real-time fast PCR. The method was proven to allow the detection of transfusions up to a donor percentage of 1%, with a significant improvement in terms of sensitivity with respect to both the reference cytofluorimetric method and a previously proposed strategy based on the DNA STR-based strategy.

Evaluation of the detection of the homologous transfusion of a red blood cell concentrate in vivo for antidoping

Two doping cases of homologous blood transfusion (HBT) during Tokyo 2020 Summer Olympics have shown that more controls are needed. The method of detection using flow cytometry to evaluate the expression of minor blood group antigens from red blood cells (RBCs) and identify different RBC populations is efficient but still complex to perform with multiple antigens detection. Recently, the interest of using forensic DNA analysis was also highlighted as a potential new method to detect HBT, with possibility to start from dried blood spots (DBS) instead of fresh blood. After a first phase of development, a protocol was validated for HBT detection using DNA analysis after extraction from DBS. Presence of a second DNA was clear down to 2% of donor blood in vitro. A flow cytometry protocol was also developed with preparation and analysis in 96-well plates and detection of two different antigens per well using two secondary antibodies with distinct fluorophores. The objective of the project was to evaluate the window of detection of an HBT performed in vivo with 150 mL of RBC concentrate. Blood samples obtained over 7 weeks post-transfusion were analyzed. DNA profiling from DBS was not sensitive enough to detect the presence of a second DNA even 1 day after transfusion. On the contrary, the flow cytometry protocol was very efficient and allowed identification of several double populations of RBC (expressing/non-expressing several antigens) until day 50 post-transfusion. This protocol can be fully validated for a future application to doping control samples.

Untargeted Metabolomics Identifies a Novel Panel of Markers for Autologous Blood Transfusion

Untargeted metabolomics was used to analyze serum and urine samples for biomarkers of autologous blood transfusion (ABT). Red blood cell concentrates from donated blood were stored for 35−36 days prior to reinfusion into the donors. Participants were sampled at different time points post-donation and up to 7 days post-transfusion. Metabolomic profiling was performed using ACQUITY ultra performance liquid chromatography (UPLC), Q-Exactive high resolution/accurate mass spectrometer interfaced with a heated electrospray ionization (HESI-II) source and Orbitrap mass analyzer operated at 35,000 mass resolution. The markers of ABT were determined by principal component analysis and metabolites that had p < 0.05 and met ≥ 2-fold change from baseline were selected. A total of 11 serum and eight urinary metabolites, including two urinary plasticizer metabolites, were altered during the study. By the seventh day post-transfusion, the plasticizers had returned to baseline, while changes in nine other metabolites (seven serum and two urinary) remained. Five of these metabolites (serum inosine, guanosine and sphinganine and urinary isocitrate and erythronate) were upregulated, while serum glycourdeoxycholate, S-allylcysteine, 17-alphahydroxypregnenalone 3 and Glutamine conjugate of C6H10O2 (2)* were downregulated. This is the first study to identify a panel of metabolites, from serum and urine, as markers of ABT. Once independently validated, it could be universally adopted to detect ABT.

Detection of Homologous Blood Transfusion in Sport Doping by Flow Cytofluorimetry: State of the Art and New Approaches to Reduce the Risk of False-Negative Results

This article presents the results of a study aimed to give new suggestions and strategies for improving the implementation of the flow cytofluorimetry-based method for the detection of homologous blood transfusions in doping control. The method is based on the recognition of the phenotypic mismatch between minority blood group antigens possessed by the donor and the recipient. Two strategies have been followed to reduce the risk of false-negative results: (i) the monitoring of a broader range of erythrocytes surface antigens; and (ii) the application of different surface erythrocyte staining protocols, tailored on the different antigens and the type of antigenic mismatch that had to be detected (whether it is the donor or the recipient who expresses or not the antigen to be detected). Special attention has also been focused on the time factor, to avoid prolonged sample storage, since hemolysis may have a significant impact on the reliability and quality of the results. Our experimental evidence suggests that the risk of false-negative results can be minimized by (i) the expansion of the antigen panel, with the inclusion of four additional targets; (ii) a more accurate selection of the gating area of the red blood cells; (iii) the choice of a better fluorochrome (alexa fluor 488) to be conjugated to the secondary antibody; and (iv) the implementation of different staining protocols depending on the nature of the double population to be detected (donor expressing vs. recipient non-expressing and vice versa). The combination of the above approaches allowed a significant reduction of false-negative results, assessed on samples simulating a homologous blood transfusion between two compatible subjects.

Analytical progresses of the World Anti-Doping Agency Olympic laboratories: a 2016 update from London to Rio

The 2016 Olympic and Paralympic Games, the biggest event in human sports, was held in Rio de Janeiro with more than 10,500 athletes from 206 countries over the world competing for the highest of sports honors, an Olympic medal. With the hope that the Olympic ideal accompanies all aspects of the XXXI Olympiad, WADA accredited antidoping laboratories use the spearhead of analytical technology as a powerful tool in the fight against doping. This review summarizes the main analytical developments applied in antidoping testing methodology combined with the main amendments on the WADA regulations regarding analytical testing starting from the 2012 London Olympics until the 2016 Olympic Games in Rio de Janeiro.