Lectins as Tools for the Purification of Liver Endothelial Cells

Successful procedures for the isolation and culture of large-vessel endothelial cells (EC), were first reported in the earlyseventies (
1
,
2
). Since then, microvascular EC have been isolated from various organs, such as adrenal gland (
3
), brain (
4
), skin (
5
), retina (
6
), and myocardium (
7
). The initial steps of the conventional methods for EC isolation involve mechanical and/or enzymatic dissociation of thetissues, followed by filtration and pelleting of cells. A number of special techniques have been developed to eliminate contaminatingcell types and enrich endothelial cells in mixed cell populations. These include: manual removal of nonendothelial cell types;use of selective media; plating cells on gelatin or fibronectin-coated dishes, and Percoll gradient centrifugation (
8
,
9
). The main problem with the conventional methods is that they are labor intensive and often do not produce pure EC populations. A more advanced approach is to use fluorescent-activated cell sorting (FACS) which allows sorting based on specific surfaceantigens or metabolic differences. Auerbach et al. used FACS for EC isolation, using an antibody against angiotensin convertingenzyme (
10
). Later, Voyta et al. sorted EC, based on their uptake of acetylated low-density lipoprotein (
11
). Cell separation techniques using magnetic affinity are based on similar principles as the FACS, but do not involve expensiveequipment. In this chapter, we describe liver endothelial cell isolation, using lectin-coated magnetic beads (
12
).