Endothelial Cell Activity in Sickle Cell Anemia
Vaso-occlusive phenomena in-duce acute painful crises in sickle cell anemia. It is felt that endothelial cell activity may play a central role in producing vascular effects. A variety of disorders in which vascular injury occurs (e.g., cytomegalovirus infection, rickettsial infection, intravascular instrumentation) are associated with increased numbers of circulating endothelial cells. The authors of this trial examined aspects of endothelial cell function in patients with sickle cell anemia, comparing patients at times of acute painful crisis with stable patients.
Sickle cell anemia patients in crisis had almost double the level of circulating endothelial cells than when not in crisis, and comparative measurements detected a trend toward a rising number at the onset of the acute painful crisis. Baseline levels of circulating endothelial cells were five times as high in sickle cell anemia patients as in normal controls or non-sickle cell anemias.
Endothelial cells in sickle cell anemia patients were found not only to be more plentiful, but also more often in the activated state. Unfortunately, the activated state in this disorder appears to be aberrant, in that there is an imbalanced pro-coagulant and pro-adhesive activity, promoting vasoconstriction, abnormal red and white cell adhesion to the vascular wall, and coagulation.
As our knowledge of the functions and alteration of endothelial cells advances, tools that modulate endothelial cell activity may prove clinically useful.
Solovey A, et al. N Engl J Med 1997; 337:1584-1590.