Established and experimental treatments for sickle cell disease.

Sickle cell disease (SCD) is characterized by the presence of sickle hemoglobin (HbS), which has the unique property of polymerizing when deoxygenated. The sickling process is markedly accelerated when intracellular concentration of HbS is increased. Due to the unique dependence of HbS polymerization on its cell concentration, a slight reduction in HbS concentration is likely to have a beneficial effect on the kinetic of polymerization and on the generation of dense, dehydrated red cells. The pathophysiology of acute and chronic clinical manifestations of SCD is strictly related to the hemoglobin cyclic polymerization, to the generation of dense, dehydrated red cells and to the interaction between sickle red cells and abnormal activated vascular endothelial cells. In the present paper we have reviewed the principal therapeutic strategies and we have explored the future treatment options for sickle cell disease. Therapy of sickle cell disease is based on two major goals. The first one is the decrease in intracellular HbS concentration obtained with agents activating fetal hemoglobin synthesis, such as hydroxyurea (HU) or with erythrocyte-active agents blocking different red cell membrane ion pathways and preventing sickle cell dehydration. The second one is based on therapeutic strategies, which may reduce sickle cell-endothelial adhesive events.