Swine hemoglobin as a potential source of artificial oxygen carriers, hemoglobin-vesicles

Hemoglobin-based oxygen carriers (HBOCs) have been developed as a transfusion alternative and oxygen therapy. The Hb source is usually outdated donated human blood or cow blood obtained from cattle industries because of its abundance. This study examined the feasibility of using swine Hb ((S)Hb) for preparation of cellular-type HBOCs, hemoglobin-vesicles (HbV). Purification of (S)Hb from fresh swine whole blood was conducted with processes including carbonylation ((S)HbO(2) --> (S)HbCO), pasteurization (60 °C, 15 hours) and tangential flow ultrafiltration, with yield of 90%. Actually, differential scanning calorimetric analysis showed a denaturation temperature of (S)HbCO at 83 °C and assures its stability during pasteurization. Concentrated (S)HbCO together with pyridoxal 5'-phosphate (PLP) as an allosteric effector was encapsulated in phospholipid vesicles to prepare (S)HbV. After decarbonylation ((S)HbCO --> (S)HbO(2)), the oxygen affinity (P(50)) of (S)Hb changes mainly by PLP, and the influence of Cl(-) was small, in a manner similar to that of human Hb ((H)Hb). However, after encapsulation, vesicles of (S)HbV showed much lower oxygen affinity (higher P(50)) than (H)HbV did. Autoxidation of (S)HbV was slightly faster than (H)HbV. Although some differences are apparent in oxygen affinity and autoxidation rates, results clarified that (S)Hb is useful as a starting material for HbV production.