Development of a Cell Line from the American Eel Brain Expressing Endothelial Cell Properties

A cell line (eelB) was developed from the outgrowth of adherent cells from brain explants of the American eel, Anguilla rostrata (Lesueur). EelB cells have been grown routinely in L-15 with 10% fetal bovine serum (FBS), undergone over 100 passages, and cryopreserved successfully. The cells from late-passage cultures (>45) were polygonal, formed capillary-like structures (CLS) on Matrigel, and stained immunocytochemically for von Willebrand factor (vWF) and for three tight junction proteins, zonula occludens-1 (ZO-1), claudin 3, and claudin 5. These results suggest that eelB is an endothelial cell line, one of the few from fish and the first from the brain. Despite this, eelB did not respond to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) with the induction of CYP1A protein. The cells from early-passage cultures (<20) had more varied shapes and did not form CLS on Matrigel. Only cells from early-passage cultures formed in suspension three-dimensional aggregates that had some cells expressing alkaline phosphatase and nestin. These cells are thought to be neural stem cells and the aggregates neurospheres. The emergence of endothelial-like cells upon the continued subcultivation of cells from early-passage cultures that had neural stem cells has been described previously for mammals, but this is a first for teleosts. Remarkably, cells from all passage levels were stained strongly for senescence-associated β-galactosidase (SA β-Gal) activity.