Generation of enzyme-converted type O whole blood from type A whole blood: A translational study using swine whole...

Low-titer O whole blood (LTOWB) is increasingly used to improve trauma outcomes, but maintaining supplies remains challenging, particularly in austere environments. This study evaluated EnzAO1 (FpGalNAcDeAc) and EnzAO2 (FpGalNase) to generate enzyme-converted O type whole blood (ECO-WB) from A type swine whole blood (WB).

WB from 16 A type and 4 O type swine were collected in Citrate Phosphate Dextrose Adenine-1 (CPDA-1). Type A WB was randomized to enzymatic conversion at either room temperature or 4°C. Each unit was divided into 45 mL aliquots and treated with no enzyme or one of four enzyme concentrations (1.75-17.5 μg/mL). Samples were analyzed at 15, 30, 60, and 120 min. A-antigen reduction was measured by flow cytometry. Blood counts, blood gases, rotational thromboelastometry, osmotic fragility, and free hemoglobin were used to assess blood post-conversion.

Enzymatic treatment converted A type swine WB to ECO-WB in a concentration- and time-dependent manner. At the highest enzyme concentration (17.5 μg/mL), A antigen expression was reduced to 0.6% ± 0.2% by 15 min, comparable to the signal observed in type O controls (0.45% ± 0.45%). No significant differences in antigen conversion were observed between temperature conditions. ECO-WB demonstrated stable hematologic profiles compared to controls.

This study demonstrates enzymatic conversion of type A swine WB into ECO-WB, reducing A antigen expression comparable to type O WB without compromising blood quality. The process is compatible with refrigerated and room temperature storage, supporting its application in diverse clinical and operational settings.