Development of Neo Red Cells(NRC) with the Enyzmatic Reduction System of Methemoglobin

Abstract

To assess the oxygen transport capacity and safety of Neo Red Cells (NRC) with the enzymatic reduction system of methemoglobin in vitro and in experimental animals. Stroma free hemoglobin (SFH) prepared without damage of enzymes from outdated human red blood cells, together with inositol hexaphosphate as an allosteric effector, NAD as a coenzyme and glucose, adenine and inosine as a substrate was encapsulated within liposomes composed of hydrogenated soy phosphatidylcholine, cholesterol, myristic acid and α-tocopherol in the ratio of 7:7:2:0.28 respectively. NRC thus prepared with a mean diameter of 220nm, encapsulation efficiency of 1.3g-Hb:1g-lipid and P₅₀O₂ of 50–60mmHg were then coated with polyethylene glycol bound to hydrogenated soy phosphatidylethanolamine as a surface modifier to prevent aggregation of NRC in plasma. The methemoglobin formation of the NRC with enzymatic reduction system were evaluated by in-vitro examination and exchange transfusion with rats as in-vivo examination, then the methemoglobin formation was reduced from 1%/hr to 0.4%/hr by the addition of methemoglobin reduction system. The generation of the pyruvate and the lactate were observed within the NRC with enzymatic reduction system, then the activation of the Embden-Meyerhof pathway was confirmed. And we concerned about the availability of the NRC as a perfusate for the cardiopulmonary bypass during moderate or profound hypothermia, then we evaluated the oxygen transporting efficiency and capacity of the NRC under the using of the artificial lung system in vitro examination. The present investigation suggest that the effectiveness of the NRC with enzymatic reduction system, they restrained the formation of methemoglobin and they are efficient oxygen carriers as a perfusate of the artificial lung, and we suggest the new extracorporeal circulation system using of the NRC as a perfusate for the cardiopulmonary bypass.

Key Words:

• Blood substitutes
• Liposome encapsulated hemoglobin
• Liposome surface modification
• Anemia
• Oxygen carrier
• methemoglobin reduction system