Sickle erythrocytes adhere to endothelial cell monolayers (ECM's) exposed to flowing blood.
In order to determine whether the phenomenon of sickle erythrocyte adherence to cultured vascular endothelium exists under conditions of blood flow, we exposed monolayers of bovine aortic endothelial cells to flowing sickle cell blood under controlled conditions in a specially designed flow chamber. Individual red cells were imaged by means of epifluorescent videomicroscopy, five percent of the total number of red cells in an aliquot of blood having been labelled by the passive uptake of sodium fluorescein isothiocyanate. At a shear rate of 270 sec-1 at the blood-monolayer interface, red cells from sickle cell blood frequently adhered to the monolayer for periods ranging from 100's of m sec to greater than 30 sec. With adhesion defined as the average number of adherent red cells during the sixth minute of blood flow (corrected upward to account for unlabelled erythrocytes), adhesion with sickle cell blood was of the order of 10(4) erythrocytes/cm2 ECM and exceeded (p less than 0.001) that for normal blood by a factor of 5.6. Further studies utilizing in situ displacement of blood with culture medium followed by brightfield microscopy indicate that the adherent cells were predominantly discocytes having single points of tethering to unknown sites on the monolayer. Adhesion of sickle cell erythrocytes to endothelium, therefore, is a very real phenomenon under physiologic conditions of blood flow; this phenomenon may contribute to the pathophysiology of vaso-occlusive events seen in sickle cell disease.
D000755:Anemia, Sickle Cell / Q000097:blood*; D001696:Biomechanical Phenomena; D002448:Cell Adhesion; D002478:Cells, Cultured; D004727:Endothelium / Q000502:physiology; D004912:Erythrocytes / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D066298:In Vitro Techniques; D008856:Microscopy, Fluorescence