Use of a flow‐cell system to investigate virucidal dimethylmethylene blue phototreatment in two RBC additive solutions

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Abstract
BACKGROUND: Limited photoinactivation kinetics, use of low‐volume 30 percent Hct RBCs, and hemolysis have restricted the practicality of the use of dimethylmethylene blue (DMMB) and light for RBC decontamination. A flow‐cell system was developed to rapidly treat larger volumes of oxygenated 45 percent Hct RBCs with high‐intensity red light.MATERIALS AND METHODS: CPD‐whole blood was WBC reduced, RBCs were diluted in additive solutions (either Adsol or Erythrosol), and suspensions were subsequently oxygenated by gas overlay. Intracellular or extracellular VSV and DMMB were sequentially added. VSV‐infected RBC suspensions (45% Hct) were passed through 1‐mm‐thick flow cells and illuminated. Samples were titered for VSV, stored for up to 42 days, and assayed for Hb, supernatant potassium, ATP, and MCV.RESULTS: The use of oxygenated RBCs resulted in rapid and reproducible photoinactivaton of ≥6.6 log extracellular and approximately 4.0 log intracellular VSV independent of additive solution. Phototreated Adsol RBCs exhibited more than 10 times greater hemolysis and 30 percent greater MCV during storage than identically treated Erythrosol RBCs. Phototreatment caused RBC potassium leakage from RBCs in both additive solutions. ATP levels were better preserved in Erythrosol than Adsol RBCs.CONCLUSION: A rapid, reproducible, and robust method for photoinactivating model virus in RBC suspensions was developed. Despite improved hemolysis and ATP levels in Erythrosol‐phototreated RBCs, storage properties were not maintained for 42 days.