Effect of phenylalanine- or tryptophan-loaded liposomes on the rheological properties of AA and SS erythrocytes.

Phenylalanine or tryptophan was incorporated into AA and SS red blood cells by a liposomal transport system which was previously shown by Kumpati to inhibit and reverse sickling of intact SS red blood cells in vitro. In the present study, the effect of phenylalanine or tryptophan incorporation on the rheological properties was evaluated. The incorporation of phenylalanine or tryptophan into red blood cells decreased the viscosity of deoxy SS red blood cells which reached a level close to that for normal red blood cells due to the antisickling effect. These results demonstrate that this liposomal transport system which transferred phenylalanine or tryptophan into intact red cells and did not have any adverse effect on red cell metabolism or function did correct the viscosity of deoxy SS red cells by its antisickling effect. This method may have significant therapeutic implications in the treatment of sickle cell disease.