In Focus
From Donor to recipient
What we learn from vein-to-vein databases

Every red blood cell (RBC) unit has a story. From the moment it is drawn from a volunteer donor until it circulates in a transfusion recipient, the unit is shaped by a complex web of biological, genetic, manufacturing, and clinical factors.
For decades we have known that transfusion outcomes vary widely between patients, even when they receive the same volume of blood. Some RBC units seem to produce robust hemoglobin increments, while others provide only modest benefit. Until recently, we lacked the tools to fully understand why. The advent of large-scale “vein-to-vein” databases has begun to change that. By linking donor information, product manufacturing details, and recipient outcomes across tens of thousands of transfusion episodes, we are able to trace the journey of each RBC unit from donor vein to recipient vein and ask: which traits of donors and products consistently predict better transfusion outcomes, and how might this knowledge shape the future of transfusion medicine? The Recipient Epidemiology and Donor Evaluation Study (REDS-III) has been central to this effort. Through this United States National Institutes of Health funded initiative, we have been able to link comprehensive data from more than 13,000 blood donors with outcomes in thousands of transfusion recipients. The resulting vein-to-vein database includes donor demographics, genetics, metabolomics, and environmental exposures, as well as product information such as storage duration, irradiation, and additive solutions. Critically, these donor and product variables are directly linked to transfusion recipient outcomes, including hemoglobin levels measured before and after transfusion. This infrastructure has allowed us to move beyond anecdotal observations and more rigorously evaluate the variability in transfusion effectiveness.
Early analyses confirmed that conventional factors such as donor age, sex, and race or ethnicity, along with product features like irradiation or prolonged storage, influence how much a patient’s hemoglobin rises after transfusion. But these features accounted for only part of the variability. The real breakthrough came from incorporating molecular data. By combining metabolomic profiling with genome-wide association analyses, we identified metabolic signatures that predict transfusion effectiveness and linked them to specific genetic variants in blood donors. For example, elevated levels of hypoxanthine, a purine breakdown product, correlate with reduced hemoglobin increments, while kynurenine metabolism—regulated by variants in the transporter SLC7A5—affects osmotic fragility and transfusion outcomes. Similarly, urate and lipid peroxidation products such as HETE are tied to variation in genes like ABCG2 and P53, and each independently reduces post-transfusion hemoglobin increments.
When we examined more than 6,000 single-unit transfusion episodes, these molecular and genetic markers proved to be independent predictors of transfusion effectiveness, even after accounting for traditional donor and product characteristics. Units from donors carrying certain high-risk alleles reduced hemoglobin increments by about 0.05 to 0.15 g/dL on average. While these numbers may sound modest, the broader clinical implications are not. Patients who depend on chronic transfusion—such as those with sickle cell disease, thalassemia, or myelodysplastic syndromes—experience these differences repeatedly.
Over time, the result is a measurable increase in transfusion burden, exposing patients to more donor units, more iron overload, and greater risk of alloimmunization or transfusion reactions. Even in acute care settings, recipients of units from high-risk donors were more likely to require additional transfusions during their hospital stay, underscoring the real-world consequences of these biological differences.
The vision that emerges from this work is a new model of precision transfusion medicine. Just as oncology now considers tumor genomics when choosing a treatment, we can begin to imagine a transfusion service that considers donor genomics and metabolomics when selecting blood units for patients. A possible framework might involve genetic characterization of donors at first donation, coupled with periodic metabolomic profiling at subsequent donations. This information could then be integrated into blood inventory management systems, guiding allocation of units. Instead of “first-in, first-out,” units could be issued based on predicted effectiveness, with high-yield units reserved for patients most in need. Over time, this could reduce the number of transfusions required, lower costs, and improve patient quality of life and other outcomes, while also reducing stress on the blood supply. Of course, challenges remain. Most of the studies to date, including our own, are observational, which means we cannot fully prove causality. Prospective studies are needed to validate whether directing specific units to specific patients based on molecular signatures truly improves clinical outcomes. There are also questions of feasibility and cost. Genetic and metabolic screening of all donors may sound daunting, though the falling cost of sequencing and high-throughput assays makes it increasingly plausible. Equity must also be carefully considered: ensuring that personalized transfusion approaches do not inadvertently create disparities in access to optimal units is essential. Despite these challenges, the scientific signal is clear. Transfusion effectiveness is not random. It is, at least in part, predictable—and if it is predictable, it can be managed. The broader implications of vein-to-vein databases extend beyond RBCs. They offer a template for how transfusion medicine can evolve into a more data-driven and patient-centered practice. By linking molecular traits of donors with real-world outcomes in recipients, we can not only improve transfusion effectiveness but also shed light on fundamental aspects of human biology, from red cell metabolism to genetic determinants of oxidative stress. These insights feed back into donor health, recipient outcomes, and the overall stewardship of our precious blood supply. In the end, what is most exciting is the possibility that every transfusion might someday be tailored to maximize benefit for the patient. The blood system has always depended on the generosity of donors and the skill of laboratory professionals. With the addition of advanced analytics and molecular profiling, we now have the opportunity to honor that generosity by ensuring that each unit of blood is used as effectively as possible. From donor vein to recipient vein, the path of a RBC unit can now be mapped with unprecedented detail, providing both a scientific roadmap and a moral imperative: to deliver the right unit to the right patient at the right time.
References
- Nareg H Roubinian, Colleen Plimier, Jennifer P Woo, Catherine Lee, Roberta Bruhn, Vincent X Liu, Gabriel J Escobar, Steven H Kleinman, Darrell J Triulzi, Edward L Murphy, Michael P Busch Effect of donor, component, and recipient characteristics on hemoglobin increments following red blood cell transfusion Blood 2019; PMC6764268
- Nareg H. Roubinian, Sarah E. Reese, Hannah Qiao, Colleen Plimier, Fang Fang, Grier P. Page, Ritchard G. Cable, Brian Custer, Mark T. Gladwin, Ruchika Goel, Bob Harris, Jeanne E. Hendrickson, Tamir Kanias, Steve Kleinman, Alan E. Mast, Steven R. Sloan, Bryan R. Spencer, Steven L. Spitalnik, Michael P. Busch, Eldad A. Hod on behalf of the National Heart Lung and Blood Institute (NHLBI) Recipient Epidemiology and Donor Evaluation Study IV Pediatrics (REDS-IV-P). Donor genetic and nongenetic factors affecting red blood cell transfusion effectiveness JCI Insight 2021; PMC8765041
- Nareg H Roubinian, Colleen Plimier, Fang Fang, Grier P Page, Travis Nemkov, Tamir Kanias, Brian Custer, Steven Kleinman, Philip J Norris, Michael P Busch, Angelo D’Alessandro Integrated analysis of blood donor metabolic phenotypes and genetic traits on red blood cell transfusion effectiveness Blood RCI 2025
