Bovine brain endothelial cells express tight junctions and monoamine oxidase activity in long-term culture

International audienceThe passage of substances across the blood-brainbamer is regulated by cerebral capillaries which possess certain distinctly different morphological and enzymatic properties compared to capillaries of other organs. Investigations of the functional characteristics of brain capillaries have been facilitated by the use of cultured brain endothelial cells, but in most studies a number of characteristics of the in vivo system are lost. To provide an in vitro system for studies of brain capillary functions, we developed a method of isolating and producing a large number of bovine brain capillary endothelialcells. These cells, absolutely free of pericyte contamination,are subcultured, at the split ratio of 1:20 (20-fold increase of the cultured surface), with no apparent changes in cell morphology up to the fiftieth generation (10 passages). Retention of endothelial-specific characteristics (factor VIII-related antigen, angiotensin-converting enzyme, and nonthrombogenic surface) is shown for brain capillaryderivedendothelial cells up to passage 10, even after frozenstorage at passage 3. Furthermore, we showed that bovinebrain capillary endothelial cells retain, up to the fiftieth generation, some of the characteristics of the blood-brain bamer: occurrence of tight junctions, paucity of pinocytotic vesicles, and monoamine oxidase activity