Vascular Obstruction in Sickle Cell Disease

Initially, the pathophysiology of sickle cell anemia was attributed to deoxygenation-induced polymerization of a mutant form of hemoglobin, hemoglobin S, as well as sickling of red blood cells that plug blood vessels causing the onset of a painful vasoocclusive crisis. Although hemoglobin S polymerization is central to the pathophysiology of this disease, the initiation of a vasoocclusive episode may involve multiple factors that disrupt the steady state and promote intravascular red blood cell sickling. Reversible sickling, red blood cell abnormalities, and transient ischemic events in this disease may cause endothelial injury resulting in abnormal erythrocyte-endothelium interactions, induction of inflammatory cytokines, leukocyte recruitment, and altered vascular tone. These factors can promote intravascular sickling by delaying red blood cell transit times in the microcirculation. This review briefly describes the role of these factors and some novel therapeutic approaches based on anti-adhesive and anti-inflammatory agents.