In vivo visualization of hemodialysis-induced alterations in leukocyte- endothelial interactions

Abstract

Background. The aim of this study was to develop a model for hemodialysis (HD) in small animals using conventional dialysis equipment that would allow the intravital microscopic observation of leukocyte-endothelial interactions in vivo. Methods. Cuprophan dialyzers were adapted to obtain a similar ratio of membrane area to blood volume as in clinical HD. A silicone ring was inserted into the dialyzer's inlet to limit the number of blood- perfused capillaries. Rabbits were dialyzed for one hour without a dialysate flow. Results. Extracorporeal circulation with the cuprophan dialyzer resulted in a transient leukopenia and complement activation. At the nadir of leukopenia, leukocytes that rolled along the venular wall were scarcely observed, whereas rolling was abundant (54 ± 9 per min) prior to extracorporeal circulation. The adhesion of leukocytes to the vascular endothelium was not induced. After 60 minutes rolling of leukocytes was still reduced by 73 ± 5.5%, despite the full recovery of circulating leukocyte counts. Extracorporeal circulation without a dialyzer also tended to reduce leukocyte rolling, although systemic leukocyte counts were not affected. Conclusions. The use of adapted conventional cuprophan hemodialyzers in rabbits yielded a transient leukopenia similar to that in clinical HD. Using intravital microscopy, we demonstrated impairment of leukocyte-endothelial interactions. In addition, our data indicate that tissues, in which leukocytes can roll and adhere, are not automatically sites of leukocyte sequestration during HD-induced leukopenia.