Crizanlizumab (ADAKVEO®, Novartis, Switzerland) a monoclonal P-selectin blocking antibody designed to disrupt the blood cells and endothelium interactions in sickle cell disease (SCD) patients, which leads to reduction of vaso-occlusive crises, the major manifestation of the disease. We report the novel microfluidic platform (endothelium-on-a-chip), to test the effects of Crizanlizumab on the adhesion of red blood cells (RBCs) to perfusion-cultured, acutely and chronically activated human endothelial cells (ECs).