On the trail of blood doping-microRNA fingerprints to monitor autologous blood transfusions in vivo

A pipeline for the development and analysis of extracellular vesicle-based transcriptomic biomarkers in molecular diagnostics

Extracellular vesicles are shed by every cell type and can be found in any biofluid. They contain different molecules that can be utilized as biomarkers, including several RNA species which they protect from degradation. Here, we present a pipeline for the development and analysis of extracellular vesicle-associated transcriptomic biomarkers that our group has successfully applied multiple times. We highlight the key steps of the pipeline and give particular emphasis to the necessary quality control checkpoints, which are linked to numerous available guidelines that should be considered along the workflow. Our pipeline starts with patient recruitment and continues with blood sampling and processing. The purification and characterization of extracellular vesicles is explained in detail, as well as the isolation and quality control of extracellular vesicle-associated RNA. We point out the possible pitfalls during library preparation and RNA sequencing and present multiple bioinformatic tools to pinpoint biomarker signature candidates from the sequencing data. Finally, considerations and pitfalls during the validation of the biomarker signature using RT-qPCR will be elaborated.

Use of RNA biomarkers in the antidoping field

There is growing evidence that various RNA molecules can serve as biomarkers for clinical diagnoses. Over the last decade, the high specificities and sensitivities of RNA biomarkers have led to proposals that they could be used to detect prohibited substances and practices in sports. mRNAs and circulating miRNAs have the potential to improve the detection of doping and expand the performance of the Athlete Biological Passport. This review provides a summary of the use of RNA biomarkers to detect human and equine doping practices, including a discussion of the use of dried blood spots as a stable matrix that supports and improves the general process of RNA biomarker detection. The advantages of RNA biomarkers over protein biomarkers are also discussed.

Athlete biological passport: longitudinal biomarkers and statistics in the fight against doping

As novel substances, short time windows, and limits of detection increasingly challenge direct methods of doping detection in sports, indirect tools inevitably take a greater role in the fight against it. One such tool is the athlete biological passport (ABP) - a longitudinal profiling of the measured haematological and biochemical biomarkers, combined with calculated scores, against the background of epidemiological data crucial for doping detection. In both of its modules, haematological and steroidal, ABP parameters are analysed with the Bayesian adaptive model, which individualises reference and cut-off values to improve its sensitivity. It takes into account the confounding factors with proven and potential influence on the biomarkers, such as race and altitude exposure. The ABP has already changed the fight against doping, but its importance will further grow with the new modules (e.g., endocrinological), parameters (e.g., plasma volume-independent parameters), and complementing indirect methods (e.g., transcriptomic).

Indirect biomarkers of blood doping: A systematic review

The detection of blood doping represents a current major issue in sports and an ongoing challenge for antidoping research. Initially focusing on direct detection methods to identify a banned substance or its metabolites, the antidoping effort has been progressively complemented by indirect approaches. The longitudinal and individual monitoring of specific biomarkers aims to identify nonphysiological variations that may be related to doping practices. From this perspective, the identification of markers sensitive to erythropoiesis alteration is key in the screening of blood doping. The current Athlete Biological Passport implemented since 2009 is composed of 14 variables (including two primary markers, i.e., hemoglobin concentration and OFF score) for the hematological module to be used for indirect detection of blood doping. Nevertheless, research has continually proposed and investigated new markers sensitive to an alteration of the erythropoietic cascade and specific to blood doping. If multiple early markers have been identified (at the transcriptomic level) or developed directly in a diagnostics' kit (at a proteomic level), other target variables at the end of the erythropoietic process (linked with the red blood cell functions) may strengthen the hematological module in the future. Therefore, this review aims to provide a global systematic overview of the biomarkers considered to date in the indirect investigation of blood doping.

Whispers in the Blood: Leveraging MicroRNAs for Unveiling Autologous Blood Doping in Athletes

The prevalence of autologous blood transfusions (ABTs) presents a formidable challenge in maintaining fair competition in sports, as it significantly enhances hemoglobin mass and oxygen capacity. In recognizing ABT as a prohibited form of doping, the World Anti-Doping Agency (WADA) mandates stringent detection methodologies. While current methods effectively identify homologous erythrocyte transfusions, a critical gap persists in detecting autologous transfusions. The gold standard practice of longitudinally monitoring hematological markers exhibits promise but is encumbered by limitations. Despite its potential, instances of blood doping often go undetected due to the absence of definitive verification processes. Moreover, some cases remain unpenalized due to conservative athlete-sanctioning approaches. This gap underscores the imperative need for a more reliable and comprehensive detection method capable of unequivocally differentiating autologous transfusions, addressing the challenges faced in accurately identifying such prohibited practices. The development of an advanced detection methodology is crucial to uphold the integrity of anti-doping measures, effectively identifying and penalizing instances of autologous blood transfusion. This, in turn, safeguards the fairness and equality essential to competitive sports. Our review tackles this critical gap by harnessing the potential of microRNAs in ABT doping detection. We aim to summarize alterations in the total microRNA profiles of erythrocyte concentrates during storage and explore the viability of observing these changes post-transfusion. This innovative approach opens avenues for anti-doping technologies and commercialization, positioning it as a cornerstone in the ongoing fight against doping in sports and beyond. The significance of developing a robust detection method cannot be overstated, as it ensures the credibility of anti-doping efforts and promotes a level playing field for all athletes.

A panel of blood-derived miRNAs with a stable expression pattern as a potential pan-cancer detection signature

Introduction: MicroRNAs have a significant role in the regulation of the transcriptome. Several miRNAs have been proposed as potential biomarkers in different malignancies. However, contradictory results have been reported on the capability of miRNA biomarkers in cancer detection. The human biological clock involves molecular mechanisms that regulate several genes over time. Therefore, the sampling time becomes one of the significant factors in gene expression studies. Method: In the present study, we have tried to find miRNAs with minimum fluctuation in expression levels at different time points that could be more accurate candidates as diagnostic biomarkers. The small RNA-seq raw data of ten healthy individuals across nine-time points were analyzed to identify miRNAs with stable expression. Results: We have found five oscillation patterns. The stable miRNAs were investigated in 779 small-RNA-seq datasets of eleven cancer types. All miRNAs with the highest differential expression were selected for further analysis. The selected miRNAs were explored for functional pathways. The predominantly enriched pathways were miRNA in cancer and the P53-signaling pathway. Finally, we have found seven miRNAs, including miR-142-3p, miR-199a-5p, miR-223-5p, let-7d-5p, miR-148b-3p, miR-340-5p, and miR-421. These miRNAs showed minimum fluctuation in healthy blood and were dysregulated in the blood of eleven cancer types. Conclusion: We have found a signature of seven stable miRNAs which dysregulate in several cancer types and may serve as potential pan-cancer biomarkers.

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.

Autologous Blood Doping Induced Changes in Red Blood Cell Rheologic Parameters, RBC Age Distribution, and Performance

Simple Summary

Autologous blood doping (ABD) refers to the artificial increase in circulating red blood cell (RBC) mass by sampling, storage, and transfusion of one’s own blood. It is assumed that some athletes apply this prohibited technique to improve oxygen transport capacity and thus exercise performance. The primary aim of this study was to test whether RBC rheological and associated parameters significantly change due to ABD with the consideration of whether this type of measurement might be suitable for detecting ABD. Further, it was assessed whether those changes are translated into indices of endurance performance. Eight males underwent an ABD protocol combined with several blood parameter measurements and two exercise tests (pre and post transfusion). Results of this investigation suggest a change in the distribution of age-related RBC sub-populations and altered deformability of total RBC as well as of the respective sub-populations. Further, the identified changes in RBC also appear to improve sports performance. In conclusion, these data demonstrate significant changes in hematological and hemorheological parameters, which could be of interest in the context of new methods for ABD detection. However, additional research is needed with larger and more diverse study groups to widen the knowledge gained by this study.

Abstract

Autologous blood doping (ABD) refers to the transfusion of one’s own blood after it has been stored. Although its application is prohibited in sports, it is assumed that ABD is applied by a variety of athletes because of its benefits on exercise performance and the fact that it is not detectable so far. Therefore, this study aims at identifying changes in hematological and hemorheological parameters during the whole course of ABD procedure and to relate those changes to exercise performance. Eight healthy men conducted a 31-week ABD protocol including two blood donations and the transfusion of their own stored RBC volume corresponding to 7.7% of total blood volume. Longitudinal blood and rheological parameter measurements and analyses of RBC membrane proteins and electrolyte levels were performed. Thereby, responses of RBC sub-populations—young to old RBC—were detected. Finally, exercise tests were carried out before and after transfusion. Results indicate a higher percentage of young RBC, altered RBC deformability and electrolyte concentration due to ABD. In contrast, RBC membrane proteins remained unaffected. Running economy improved after blood transfusion. Thus, close analysis of RBC variables related to ABD detection seems feasible but should be verified in further more-detailed studies.

Circulating MicroRNAs as a New Class of Biomarkers of Physiological Reactions of the Organism to the Intake of Dietary Supplements and Drugs

BACKGROUND

The analysis of individual microRNAs (miRNAs) as a diagnostic and prognostic tool for the effective treatment of various diseases has aroused particular interest in the scientific community. The determination of circulating miRNAs makes it possible to assess biological changes associated with nutritional processes, the intake of dietary supplements and drugs, etc. The profile of circulating miRNAs reflects the individual adaptation of the organism to the effect of specific environmental conditions.

OBJECTIVE

The objective of this study is to systematize the data and show the importance of circulating miRNAs as new potential biomarkers of the organism's response to the intake of various dietary supplements, drugs, and consider the possibility of their use in doping control.

METHODS

A systematic analysis of scientific publications (ncbi.nlm.nih.gov) on the miRNA expression profile in response to the intake of dietary supplements and drugs most often used by athletes, and supposed their role as potential markers in modern doping control was carried out.

RESULTS

The profile of circulating miRNAs is highly dependent on the intake of a particular drug, and, therefore, may be used as a marker of the effects of biologically active supplements and drugs including the substances from the Prohibited List of the World Anti-Doping Agency (WADA).

CONCLUSION

Monitoring of circulating miRNAs can serve as a high-precision marker for detecting doping abuse in elite sports. However, it is necessary to conduct additional studies on the effect of complex drugs on the profile of circulating miRNAs and individual circulating miRNAs on a particular biological process.

Annual banned-substance review: Analytical approaches in human sports drug testing 2020/2021

Most core areas of anti-doping research exploit and rely on analytical chemistry, applied to studies aiming at further improving the test methods' analytical sensitivity, the assays' comprehensiveness, the interpretation of metabolic profiles and patterns, but also at facilitating the differentiation of natural/endogenous substances from structurally identical but synthetically derived compounds and comprehending the athlete's exposome. Further, a continuously growing number of advantages of complementary matrices such as dried blood spots have been identified and transferred from research to sports drug testing routine applications, with an overall gain of valuable additions to the anti-doping field. In this edition of the annual banned-substance review, literature on recent developments in anti-doping published between October 2020 and September 2021 is summarized and discussed, particularly focusing on human doping controls and potential applications of new testing strategies to substances and methods of doping specified in the World Anti-Doping Agency's 2021 Prohibited List.