Reducing Cell-Free Hemoglobin Levels in Freeze-dried Red Blood Cells for Transfusions in Austere Environments.

INTRODUCTION: Current storage methods for red blood cell (RBC) products require refrigeration or freezing, but this can pose significant issues in resource-constrained environments or during national emergencies where there is no access to cold storage equipment. To address this challenge, we are developing a new freeze-dried RBC product that can be stored in a dried state at ambient temperatures for long periods of time. A recently developed freeze-dried RBC product was shown to bind oxygen effectively, but increased hemolysis can occur during the freeze-drying process, which can cause toxicity during transfusion. MATERIALS AND METHODS: To mitigate the risk of adverse effects associated with free hemoglobin in transfusions of freeze-dried blood products, this study explores in-line post-processing methods that utilize chelating resin beads to effectively adsorb cell-free hemoglobin. This approach could avoid the limitations of traditional centrifugation-based free hemoglobin removal procedures, which may not be feasible in some settings where freeze-dried RBC products could be utilized. RESULTS: Non-fluidic and fluidic filtration of RBCs suspended in hemoglobin solutions decreased the amount of cell-free hemoglobin by approximately 80%-90% with no significant decreases in RBC counts. Filtration of freeze-dried and rehydrated RBCs using chelating resin beads as an adsorption matrix reduced free hemoglobin levels by more than 60% compared to freeze-dried and rehydrated RBC solutions without filtration. CONCLUSIONS: The results demonstrate the efficacy of using chelating resin beads as a post-processing technique to reduce the risk of hemolysis-mediated injury from freeze-dried RBC products. These findings are a key step toward developing effective methods to produce freeze-dried red blood cell products that are safe for transfusion in austere, resource-limited environments.