Encapsulation of Concentrated Protein Into Erythrocyte Porated by Continuous-Wave Ultrasound

A procedure of continuous-wave ultrasound (US)-induced hemolysis and reseal in solution containing water soluble protein was applied to a method for encapsulating concentrated protein solutions into resealed rat erythrocyte ghosts. To find a condition yielding a higher mean corpuscular concentration of encapsulated protein (MCC), we investigated the value of MCCs for various conditions. Additions of a small amount of plasma, Ca2+ and Mg2+ significantly increased MCC, whereas these additives did not alter the degree of hemolysis. It was suggested that plasma protect the molecular damages by the US, and that Ca2+ and Mg2+ physically stabilized the lipids of the erythrocyte membrane to fuse and reseal the pore induced by US. A maximal MCC of ∼50 mg/mL, which is 2.5 times the reported maximum amount encapsulated by the osmotic dialysis method, was obtained without a blood-washing procedure. (E-mail: masaaki.iino@it-chiba.ac.jp)