Mirages - REDS Explorer: An Online Portal for Longitudinal Metabolomics Data from the REDS-III RBC Omics Study

Over one hundred million units of packed red blood cells (pRBCs) are stored and transfused annually around the world. Storage of pRBCs in the blood bank contributes to a series of biochemical and morphological changes in pRBCs, collectively referred to as the "storage lesion(s)", that ultimately impact RBC capacity to circulate in the bloodstream of recipients, carry and deliver oxygen. A growing body of studies has shown that the metabolism of pRBCs is affected by storage duration, processing strategies, as well as donor exposures ("exposome"). The latter include diet; consumption of alcohol, caffeinated beverages; smoking; and use of medications that do not result in donor deferral. Furthermore donor genetics (e.g., sex, ethnicity, G6PD status and many other genetic traits in RBC proteins) and other biological factors (e.g., age, body mass index [BMI]) impact pRBC storage and transfusion efficacy. Despite significant advances in the characterization of the storage lesion, most omics studies have been limited in scale to tens of pRBC units. These studies thus failed to grasp the extent to which donor biology, processing strategies or other factors (exposures) impact the metabolic age of stored units (as opposed to the chronological age - i.e., days elapsed since donation). As such, it remains unclear whether or to what extent the molecular make up of a unit correlates to its hemolytic propensity and post-transfusion efficacy.

To bridge this gap, we leveraged the Recipient Epidemiology and Donor Evaluation Study-IV-Pediatric (REDS-IV-P), a research program aimed at improving blood donor safety and optimizing transfusion outcomes. Overall, 97% (13,403) of the whole blood donations provided by 13,758 donors age 18+ who provided informed consent at four different blood centers across the US were evaluable for hemolysis parameters, including spontaneous and stress (oxidative and osmotic) hemolysis analysis in ~42-day stored RBC derived from 8,502 whole blood donations. A total of 643 donors scoring in the 5^th and 95^th percentile for hemolysis parameters were invited to donate a second unit of pRBCs, which were assayed at storage days 10, 23 and 42 for hemolytic parameters and mass spectrometry-based high-throughput metabolomics. A pilot study was performed on 599 samples as part of the REDS-III RBC Omics project, while the whole recalled donor cohort was assayed as part of REDS-IV-P, for a total of serial 1,929 samples.

As part of the MIRAGES project (Metabolic Investigation of Red blood cells, as a function of Aging, Genetics, Environment and Storage), we generated the REDS Explorer portal, for real time data processing and visualization. The portal not only serves as the largest online metabolomics data repository in transfusion medicine, but also affords data elaborations, including correlations to biological characteristics (donor sex, age, BMI, blood group, Rh status), processing strategies (additive solutions, blood center, irradiation) and functional readouts (ferritin levels, hemolytic parameters). The user can adjust for relevant covariates, select specific ranges for variables such as age, and filter based on donor sex, additive solution or storage duration - while choosing between the REDS III pilot data or the REDS-IV-P full recalled donor cohort. The portal generates publication quality figures for free, direct download. For example, here we show that L-citrulline is a previously unappreciated marker of blood donor age increasing in pRBCs as a function of donor age (Figure 1.A-B - q=3.84 e-24), with opposite trends observed for hydroxyisovaleryl-carnitine (q = 3.55 e-11 Figure 1.C). The latter was then identified as the top positive correlate to donor ferritin levels at the time of donation (q = 1.47 e-16 - Figure 1.D).

The portal facilitates generation and investigation of new data-driven hypotheses, enabling the rapid dissemination and/or further mechanistic testing, thus maximizing the value of large-scale initiatives such as REDS-III/IV-P. The blood donor population as a window on the larger healthy population, high-throughput metabolomics applications in transfusion medicine, and the MIRAGES: REDS Explorer portal are directly relevant to advances in the fields of epidemiology and hematology.

Nemkov:Omix Technologies: Other: Co-Founder of Omix Technologies Inc.; Altis Biosciences LLC: Other: Co-Founder of Altis Biosciences LLC.