Endothelial cell monolayers as a model system to investigate dengue shock syndrome.

Monolayers of the human endothelial cell line ECV304 were compared with those from primary endothelial cells from human umbilical cord veins (HUVEC) for potential use as an assay system to investigate vasoactive mediator levels in dengue viral infections. Permeability increases were induced in ECV304 monolayers which were more easily reproduced than in primary cells. The cell line monolayers were considerably more stable which allowed multiple consecutive assays to be undertaken on the same monolayers. Permeability responsiveness was maximal at 2 and 3 days postseeding and declined over a period of 7 days. The cell line formed monolayers which showed time- and concentration-dependent permeability increases in response to thrombin, tumour necrosis factor-alpha (TNF-alpha) or interleukin-1alpha (IL-1alpha) in a manner similar to primary endothelial cells. Permeability increases induced by TNF-alpha were reversible and increased exposure time required a longer recovery period. The cell line, like primary endothelial cells, supported dengue viral replication. Direct infection of confluent monolayers on polycarbonate membranes was not cytolytic and did not increase the permeability of the monolayers over a 15-day period.