Neutrophil-endothelial interactions in a cell-column model of the microvasculature: effects of fMLP.
OBJECTIVE
The purpose of this study was to develop an in vitro model which, compared to stagnant two-chamber systems, is more analogous to the rheological conditions found in the vasculature and permits near simultaneous measurement of polymorphonuclear leukocytes (PMN) entrapment and endothelial, monolayer permeability.


METHODS
A previously described cell-column model of the vasculature was perfused with 2 x 10(6) PMN/ml at an average fluid velocity of 0.09 cm/s and an average estimated endothelial surface shear stress of 4.5 dyne/cm2 for a total of 60 min. PMN entrapment was estimated from counts of PMN in this recirculating system. Bovine endothelial permeability was estimated from an indicator dilution analysis of the three co-injected dyes: blue dextran (molecular weight [MW]) 2 x 10(6), sodium fluorescein (MW 342) and cyanocobalamin (MW 1355).


RESULTS
Circulation of PMN through cell-columns did not activate PMN, although the number of circulating PMN decreased at a rate of 14% per 65 cm2 of endothelial surface in the first 15 min. Endothelial cell monolayer permeability did not change within 60 min. Addition of formyl-methionyl-leucyl-phenylalanine (fMLP) (10(-5) M) activated PMN and significantly increased entrapment of circulating PMN to 27% per 65 cm2 in the first 15 min. Although the percentage of circulating PMN entrapped increased, endothelial monolayer permeability was not increased by either the addition of 10(-5)M fMLP or PMN + fMLP to the cell-column perfusate.


CONCLUSIONS
Over the 60-min period studied, entrapment of PMN within a recirculating model of the microvasculature was not associated with an increase in endothelial permeability even after PMN stimulation with fMLP.
Haselton
F R
FR
Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37235, USA.
Woodall
J H
JH
Alexander
J S
JS
D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects; D005434:Flow Cytometry; D019272:Leukocyte Elastase / Q000378:metabolism; D008833:Microcirculation / Q000187:drug effects; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D009504:Neutrophils / Q000166:cytology* / Q000187:drug effects; D010101:Oxygen Consumption; D013481:Superoxides / Q000378:metabolism; D014783:Viscosity
D013481:Superoxides; D009240:N-Formylmethionine Leucyl-Phenylalanine; D019272:Leukocyte Elastase