SCIENTISTS have developed a way of assessing the ability of red blood cells to deliver oxygen by measuring their shape. This test could improve the practice of specialist transplantation and transfusion as well as blood banking. The research is now published in open access in eBioMedicine – part of Lancet Discovery Science.
Image credit: NHS Blood and Transplant
FlowScore – a formula developed at the University of Oxford in partnership with NHS Blood and Transplant – predicts how quickly red blood cells release their oxygen. This process is important for oxygenating body tissues, including organs and muscles, especially in people receiving large transfusions.
Healthy fresh red blood cells have a distinctive biconvex shape – or dumbbell – for efficient oxygen release. During refrigerated storage, red blood cells become energetically stressed and become more spherical, which slows down the release of oxygen.
Factors affecting the release of oxygen from red blood cells were described at Oxford’s Department of Physiology, Anatomy and Genetics, but the test method was too laborious for routine use in blood organizations working to improve monitoring of blood stored for transfusion. To adapt the research findings to the blood bank, the NHS Blood and Transplant Component Development Laboratory joined the project, providing blood samples stored in accordance with NHS protocols and measurements by haematological analysers.
During routine blood tests, hematologists use flow cytometry – a method that passes cells through a laser beam to study their characteristics. When light hits a cell, the scattering pattern reveals information about their size and shape. This information was found to accurately predict the release of oxygen from red blood cells, and the predictive formula was named FlowScore. The innovation makes measurements of red blood cell oxygen transport simpler, faster and more affordable for laboratories around the world.
Blood banks can now use FlowScore as a measure of quality control during processing and storage. For example, FlowScore was able to quantify the beneficial effects of resuscitation and detect periods of blood handling outside of blood bank category conditions. The latter may be critical for monitoring stored blood quality in developing countries with higher ambient temperatures. FlowScore could also provide a way to monitor blood quality for specific vulnerable patient groups if future research shows patient benefit.
We find that FlowScore is a powerful surrogate for red blood cell oxygen handling and provides new and important information about oxygen transport through the blood. In addition to its applications in transfusion medicine and blood banking, FlowScore can help identify new genetic, environmental, and lifestyle factors that affect tissue oxygen delivery.”
Pawel Swietach, Professor of Physiology, University of Oxford
Dr Peter Smethurst, from NHSBT’s Blood and Transplant Development Laboratory, said: “FlowScore could become very fundamental to the way blood is tested to ensure its quality. It is a technical breakthrough that will improve the monitoring of stored blood and lead to improvements that will further benefit vulnerable recipients of red blood cell transfusions.”
Dr Rebecca Cardigan, Head of NHSBT’s Blood and Transplant Development Laboratory, said: “FlowScore is an accessible cell performance indicator to complement other quality metrics. It has been very exciting to conduct this cross-disciplinary and interdisciplinary collaboration, translating the excellent basic research at Oxford to provide a basis for better evaluation of stored blood and transfusion practice around the world.”
Source:
Journal Reference:
Rabcuka, J., et al. (2025). Assessment of red blood cell oxygen unloading kinetics using FlowScore, a flow cytometric index of functional blood quality. eBioMedicine. doi.org/10.1016/j.ebiom.2024.105498.
