Using redox potential as a feasible marker for banked blood quality and the state of oxidative stress in stored red blood cells.

BACKGROUND: Stored red blood cells (RBCs) may undergo oxidative stress over time, with functional changes affecting oxygen delivery. Central to these changes are oxidation-reduction (redox) reactions and redox potential (RP) that must be maintained for cell function. RP imbalance can lead to oxidative stress that may contribute to storage lesions. This study's purpose was to identify changes in RP over time in banked RBCs, and among RBCs of similar age. METHODS: Multiple random RBC segments from RBC units were tested (n = 32), ranging in age from 5 to 40 days, at 5-day intervals. RP was recorded by measuring open circuit potential of RBCs using nanoporous gold electrodes with Ag/AgCl reference. RP measures were also performed on peripheral venous blood from 10 healthy volunteers. RP measures were compared between RBC groups, and with volunteer blood. RESULTS: Stored RBCs show time-dependent RP increases. There were significant differences in Day 5 RP compared to all other groups (p ≤ 0.005), Day 10-15 vs. ages ≥ Day 20 (p ≤ 0.025), Day 20-25 vs. Day 40 (p = 0.039), and all groups compared to healthy volunteers. RP became more positive over time suggesting ongoing oxidation as RBCs age; however, storage time alone was not predictive of RP measured in a particular unit/segment. CONCLUSIONS: There are significant differences in RP between freshly stored RBCs and all others, with RP becoming more positive over time. However, storage time alone does not predict RP, indicating RP screening may be an important measure of RBC oxidative stress and serve as an RBC quality marker.

Impact of transfusion on survival in patients with myelodysplastic syndromes: Current knowledge, new insights and transfusion clinical practice.

Red Blood Cell (RBC) transfusion dependence is a prevalent consequence of anaemia in patients with lower risk Myelodysplastic Syndromes (MDS). These patients have shorter survival compared to patients responding to Erythropoiesis-stimulating agents (ESA), raising the question of potential negative effects of chronic RBC transfusions on MDS prognosis, independently of IPSS-R. Besides commonly identified complications of transfusions like iron toxicity or cardiac events, oxidative stress could be a risk factor for ineffective haematopoiesis. Recently, physicochemical changes of RBC during storage have been described. These changes called storage lesions could play a role in immunomodulation in vivo. We review the currently identified sources of potential impact on transfusion-associated effects in MDS patients and we discuss the unexplored potential role of erythrocyte-derived-extracellular vesicles. They could amplify impairment of haematopoiesis in addition to the negative intrinsic effects underlying the pathology in MDS. Thus, chronic RBC transfusions appear to potentially impact the outcome of MDS.