Liposome/heme as a totally synthetic oxygen carrier

We synthetically derived protoheme (oxygen-binding site of hemoglobin) to an amphiphilic heme compound and embedded it in the phospholipid bilayer of liposomes, not in an aqueous inside region of liposomes. This liposome/heme transports oxygen efficiently under physiological conditions. Characteristics of our totally synthetic liposome/heme as an artificial oxygen carrier, are summarized as follows. (i) Oxygen-binding is reversible and very rapid. (ii) The oxygen volume dissolved in the fluid is similar or superior to that of blood. (iii) The oxygen-binding affinity is close to that of blood. (iv) The particle size is smaller than 0.1 micron. (v) It is physically and mechanically stable under shear stress and storage. (vi) The components are synthetic derivatives of protoheme and phospholipid originated in nature. The advantages (i)-(iii) and brilliant red color of the solution are derived from the fact that our totally synthetic liposome/heme, transports oxygen in the same principle of red blood cells. When the liposome/heme solution was mixed with human blood, the liposome/heme delivered oxygen to blood in the mixture system. The oxygen-exchanging of the liposome/heme with blood was also tested ex-vivo using an artificial lung apparatus. The oxy liposome/heme was circulated through A-V of a dog leg, and the oxygen concentration was kept at a high level. This demonstrates the fact that the synthetic liposome/heme transports and delivers oxygen to the muscle tissue. Application to extracorporeal circulation and transfusion test will also be reported.