Blood-brain barrier and cell-cell interactions: methods for establishing in vitro models of the blood-brain barrier and transport measurements.

This chapter describes in vitro methods for studying the blood-brain barrier. These methods include a cell line and isolated brain microvessels. The rat brain endothelial cell line 4 (RBE4) express many properties that are expressed by brain endothelial cells in vivo. Tissue culture methods allow the investigator to design experiments for studying transporters and permeability that would be much more difficult in vivo. A method for making preparations of isolated brain microvessels also is described. These preparations are highly enriched and also can be used for studying transport in vitro, but their short life span is a limitation. Two methods are discussed for measuring transport in cell culture. In one method, permeability is measured across a cell mono-layer. This method is useful for measuring luminal and abluminal transport. The second method is especially designed for measuring the families of efflux transporters. These in vitro methods will complement many of the in vivo techniques, and they may be used as screening for more timely and expensive experiments, and also reducing the need for experimental animals.