Assessment of the oxygen transport capacity of NRCs with a 70% blood exchange in rats.

Neo red cells (NRCs) are a blood substitute representing stroma free hemolysate (SFHL) encapsulated in liposomes and containing NAD, glucose, adenine, and inosine, etc. as substrates or coenzymes of the Embden-Meyerhof pathway in RBCs and inositol hexaphosphate (IHP) as an allosteric effector. The oxygen transport efficiency (OTE) of NRCs was increased to > 45% when the oxygen partial pressure in arterial blood increased. We carried out exchange transfusion with NRCs in rats, monitored their functioning as a blood substitute in vivo, and demonstrated that NRCs worked sufficiently. First, we confirmed that the OTE of NRCs was augmented by increasing the oxygen supply to the rats by using oxygen masks. Second, we carried out 70% blood exchange with NRCs (with hemoglobin concentrations of 4, 5, 6, or 7 g/dl), and compared these experimental groups with control groups (RBC and saline). Each sample was contained bovine albumin (final volume of 5% (w/v)). As a result, the NRC groups with hemoglobin concentrations of 5, 6, and 7 g/dl showed stability after the exchange transfusion. On the other hand, the NRC group with hemoglobin concentration of 4 g/dl and the saline group showed respiratory acidosis and a drop of blood pressure and heart rate, and thus did not maintain an adequate oxygen supply. We concluded that a hemoglobin concentration of > 5 g/dl was sufficient in the NRC solution, and demonstrated in an experiment on animals that the OTE of NRCs was increased by using oxygen masks.