Oxygen-transport and solution property of polylipid/Hb

Hemoglobin entrapped with polylipid (polylipid/Hb) is one of the promising candidates as an artificial red cell based on stroma-free Hb. Stabilization of liposomes both in vitro and in vivo is achieved by the use of partially crosslinked phospholipid membranes. In this paper, the oxygen-transporting ability and solution characteristics of polylipid/Hb are described to show the possibility of using polylipid/Hb as a red cell substitute. The oxygen affinity (P₅₀) and the Hill's coefficient of polylipid/Hb were 30-40 mmHg and approximately 2 at 37°C and pH 7.4, respectively, and the oxygen transporting efficiency was 40% between 110-40 mmHg. A polylipid/Hb suspension bound oxygen completely within 5 msec as red cells do. The Hb concentration was approximately 10 g/dl. The solution property of the polylipid/Hb suspension was clarified from a viscoelastic analysis. An aqueous suspension satisfied the solution properties (osmotic pressure, pH, viscosity, etc.) in vitro as artificial blood. The colloidal osmotic pressure of polylipid/Hb was low (0.1 mmHg/g particle/dl) and could be controlled by the addition of human albumin, because the particles showed less interaction with albumin. The high oxygen-transporting ability and the good solution properties reveal high performances of polylipid/Hb as a red cell substitute.