PHYSIOLOGICAL TRANSPORT-PROPERTIES OF CULTURED RETINAL MICROVASCULAR ENDOTHELIAL-CELL MONOLAYERS

Purpose. To characterize baseline transport properties: hydraulic cond uctivity (Lp), albumin permeability (Pe), and transendothelial electri cal resistance (TER) of bovine retinal microvascular endothelial cells (RMEC) in the development of an in vitro model of the blood-retinal b arrier (BRB). Methods. RMEC were grown on porous, polycarbonate filter s for determination of the number of days required to achieve minimal transport rates. Lp, Pe, and TER were measured by utilizing a bubble t racking spectrophotometer, by quantifying the diffusional movement of fluorescein isothiocyanate-labeled albumin, and by utilizing a Millipo re electrical resistance meter, respectively. Results. Lp decreased si gnificantly from 7.82 +/- 0.85 X 10(-7) (mean +/- SEM) cm/sec/cm H2O a t post-plating Day 5 to 1.44 +/- 0.26 X 10(-7) cm/sec/cm H2O at Day 9. Pe of the monolayer also decreased progressively with days post-plati ng from 3.44 +/- 0.53 x 10(-6) cm/sec at Day 7 to a minimum of 1.95 +/ - 0.29 x 10(-6) cm/sec at Day 11. Peak TER fluctuated until Day 7, whe n it began to steadily increase from 17.14 ohm.cm(2) to a peak value o f 25.42 ohm.cm(2) at Day 10, decreasing from then on to 22.24 ohm.cm(2 ) on Day 12. Known disrupters of the BRB, NECA and VEGF elicited signi ficant increase in RMEC Lp showing the sensitivity of this model to ph armacological alterations. Conclusions. Our data indicate that RMEC gr own on polycarbonate filters form a restrictive monolayer of cells, wh ich exhibit dynamic alterations in response to pharmacological agents, thus demonstrating an in vitro model of the BRB. Future studies with the model may offer insights into the pathogenesis of retinal vascular diseases and allow convenient testing of pharmacological intervention s.