Evaluation of human hemoglobin vesicle as an oxygen carrier: recovery from hemorrhagic shock in rabbits

Abstract

The Neo Red Cell (NRC), an artificial oxygen carrier, has been developed and evaluated for its oxygen-transporting capacity, hemodynamics and safety in experimental animals. Stroma-free hemoglobin prepared from outdated human red blood cells was encapsulated in liposome capsules together with inositol hexaphosphate as an allosteric effector, coenzyme and substrates for reducing metHb formation. The NRCs were coated with polyethylene glycol bounded to phosphatidylethanolamine (PEG-PE) as a surface modifier to prevent aggregation of NRC in plasma and to prolong the circulation time in the blood stream. The formation of metHb formation was reduced from 1%/hr to 0.5%/hr by incorporating a metHb reduction system into NRC. The efficacy of the NRC in tissue oxygenation and recovery from anemia was examined in rabbits which had been made severely anemic by drawing 85% of their blood and replacing it with NRC. All the animals infused with NRC recovered to pre-anemic conditions within 6–8 hr and survived until they were sacrificed, 6 months after the exchange transfusion. Our observations suggest that NRCs constitute an efficient oxygen carrier not having serious adverse effects and associated with low metHb formation in vivo and during storage. Copyright © 2000 John Wiley & Sons, Ltd.