Research:Sickle Cell Disease is an autosomal recessive genetic disease caused by a single point mutation in the β-globin gene of hemoglobin, which leads to sickling and lysis of red blood cells (RBCs) under deoxygenated condition. Sickle RBCs (sRBCs) are not only less deformable, but also express enhanced levels of major adhesion molecules compared to RBCs of healthy patients. In addition to RBC sickling, SCD is also associated with a hyper-inflammatory state, which accounts for enhanced adherence of blood cells to vascular endothelium (monolayer of cells covering the blood vessel wall). All these factors synergistically lead to vaso-occlusion (blockage of blood vessels), which is the leading cause of morbidity in SCD patients. Although neutrophils (most abundant white blood cells in human blood) have been shown to play a role in the onset of vaso-occlusion by interacting with sRBCs in systemic venules of SCD mice, the cellular and molecular mechanism that enables systemic vaso-occlusion in human patients is not completely understood. The goal of my research is to determine the molecular and cellular mechanism of vaso-occlusion in SCD patient blood. Heparinized blood collected from race matched control and SCD patients is allowed to flow in custom-designed in vitro microfluidic channels These channels mimic the flow environment present in the human blood vessels and have a glass bottom either coated with major adhesion molecules expressed on endothelium or covered with endothelial cells derived from coronary artery of human volunteers. Interaction of blood cells with the bottom of the channels is studied using either total internal reflection fluorescence (TIRF) or epifluorescence microscopy and role of different adhesion molecules is tested using function-blocking antibodies. Understanding the role of different adhesion molecules in precipitating vaso-occlusion will be useful in designing therapeutic interventions for SCD patients.
McGowan Institute for Regenerative Medicine Scientific Retreat, Nemacolin, PA. United States of America. 3/2014