Culture and Characterization of Epithelial Cells from Bovine Choroid Plexus

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Abstract
Epithelial cells were isolated from choroid plexus, which plays a major role in cerebrospinal fluid production and regulation. Incubation of bovine choroid plexuses with pronase released cells which attached to plastic dishes with a plating efficiency of 5%. The cells were predominantly polygonal as judged by phase‐contrast microscopy. These polygonal cells undergo limited cell division and survive for 1 – 2 weeks in culture before being overgrown by fibroblasts. The fibroblastic cells could be selectively removed from the cultures by the addition of 100 μg/ml cis‐hydroxyproline to the medium for several days. The specific activities of three membrane‐bound enzymes, γ‐glutamyl transpeptidase, alkaline phosphatase, and leucine aminopeptidase were compared in selective cultures of polygonal cells and fibroblasts. Polygonal cells were found to have 4–5 times the γ‐glutamyl transpeptidase of fibroblasts, whereas fibroblasts have 2–3 times the alkaline phosphatase of polygonal cells. Leucine aminopeptidase levels in the two cultures were roughly equivalent. The polygonal cells rapidly lost γ‐glutamyl transpeptidase activity over a 4‐day period in culture but acquired increased levels of leucine aminopeptidase. Alkaline phosphatase remained roughly constant. Under similar conditions fibroblasts showed a 3‐ to 4‐fold increase in the specific activities of all three enzymes; these changes coincided with a substantial increase in cell density. Based on morphology, resistance to cis‐hydroxyproline, absence of antihemophilic factor antigen, and enzymatic characteristics, we believe the polygonal cells to be of epithelial origin.