Carrying oxygen from our lungs and releasing it to the rest of our body tissues is the primary and most vitally important function of red blood cells. With over 2 billion cases globally, anaemia is the single most prevalent impairment to human health. The biological process that is most profoundly affected in many types of anaemia is oxygen delivery. To correct this, a very common hospital intervention is a transfusion of red blood cells. According to the European Medicines Authority, 35 units of blood are transfused annually per 1,000 inhabitants in the EU (2016), using donations from 2.3% of the population. To support this demand for blood, elaborate storage facilities and logistics have been implemented in healthcare systems, such as the NHS Blood and Transplant.
DPAG scientists from the Swietach Group, working in collaboration with NHS Blood and Transplant, have shown how the process of storing blood for transfusion can have a detrimental effect on oxygen handling by red blood cells. It has been acknowledged that storage affects the biochemistry of red cells, but the impact of this on gas handling has not so far been investigated. This new study is the first demonstration that blood storage can profoundly reduce the rate of oxygen release from red cells, and potentially compromise the effectiveness of blood transfusions. Critically, the effect of storage on gas handling was found to vary substantially between blood units from different donors, and only weakly correlated to storage duration, which is currently the primary index used for quality-control in blood banks. The study also showed how rejuvenation with specially designed chemical additives can fully restore gas exchange kinetics.
According to lead author Professor Pawel Swietach, a case has been made for blood banks to implement methods for measuring gas exchange kinetics as part of quality-control and for clinical trials assessing transfusion efficacy to consider kinetics: “Transfusing red cells that are unable to release oxygen within a few seconds is clearly problematic for patients who need an immediate improvement to their oxygenation status. However, the system currently in place takes no account of the physiological quality of stored blood. Technology developed at DPAG can be implemented to assign precious blood units with a proxy for physiological quality. This would streamline resources; for example, by prioritising highest quality units for those patients who are in danger of irreversible tissue damage due to hypoxia. It will also define the expiry date of specific units in storage. Finally, our work on rejuvenation also shows how blood units can be rescued by a simple treatment at the end of storage.”
The team will continue working with the NHS and other blood bank systems to implement the technology in screening, and develop better guidelines for optimal use of blood units held for transfusion.
The full study, “Stored blood has compromised oxygen unloading kinetics that can be normalized with rejuvenation and predicted from corpuscular side-scatter” is available to read in Haematologica.