Serum levels of angiogenic factors indicate a pro-angiogenic state in adults with sickle cell disease

Hypoxia-induced angiogenesis may play an important role in the pathophysiology of sickle cell disease (SCD). Serum levels of angiopoietin (Ang)-1, Ang-2, vascular endothelial growth factor, placenta growth factor (PlGF), soluble tunica intima endothelial kinase 2 (sTIE2), erythropoietin (EPO) and endothelial activation markers (soluble vascular adhesion molecule-1, soluble intercellular adhesion molecule-1) were determined in controls, HbSS (n = 35) and HbSC (n = 23) patients. In the asymptomatic phase, serum Ang-2 (P < 0.001), EPO (P < 0.001) and sTIE2 (P = 0.03) were elevated in patients. During painful crises, increased Ang-2 (P < 0.001) and PlGF (P = 0.04) occurred in HbSS and Ang-2 (P = 0.05) in HbSC patients. These results indicate a pro-angiogenic state in SCD, mainly because of elevated Ang-2 levels.