Summary
A model has been developed to study the transport of fluid and macromolecules through
human arterial umbilical cord endothelial cell monolayers in vitro. Cells were cultured
on fibronectin- coated polycarbonate filters and formed within a few days a tight
monolayer, with an electrical resistance of 17 ± 4 Ohm · cm2. The cells were connected by close cell contacts with tight junctions. The passáge-rate
of horse radish peroxidase (HRP) through these filters was 20-40 fold lower than through
filters without an endothelial monolayer. The continuous presence of 10% human serum
was needed to maintain the electrical resistance of the monolayer and its barrier
function towards macromolecules. Chelation of extracellular calcium resulted in an
increased permeability and a decreased electrical resistance of the monolayer. This
process was reversible by re-addition of calcium ions to the cells. The permeation
rate of dextrans of various molecular weights (9-480 kD) was inversely related to
the molecular mass of the molecule. No difference was measured between the passage
rate of dextran of 480 kD and dextran of 2,000 kD. Incubation of the endothelial cell
monolayer with 2-deoxy-D-glucose resulted in a decreased permeability but it had no
effect on electrical resistance. This suggests that the passage-process is energy-
dependent.
Fluid permeation through the endothelial cell monolayer on filters was measured in
a perfusion chamber under 20 mmHg hydrostatic pressure. It was decreased by the presence
of serum proteins and responded reversibly on the chelation and readdition of extracellular
calcium ions.
Keywords
Endothelial cell monolayer - Passage of macromolecules
