Electrophysiological and biochemical characterization of a continuous human astrocytoma cell line with many properties of well-differentiated astrocytes.

Astrocytes comprise about 25% of the cellular volume of the brain, and their main function is to maintain homeostasis of the neuronal environment. These cells are commonly identified on the basis of their membrane electrical properties and the presence of specific proteins. We have characterized the human astrocytoma cell line designated UC-11MG and have shown these cells have many of the traits of differentiated astrocytes. Many of the UC-11MG cells have a large resting membrane potential, averaging -74 mV. The slope of the Em vs log [K]o cuve was 58.5 mV per decade [K]o. The cells were inexcitable when exposed to brief depolarizing current pulses. The astrocytoma traits are virtually identical to those previously reported for normal astrocytes. The astrocytoma cells also express glutamine synthetase activity which is considered specific to astrocytes among brain cells. Previous work had also demonstrated the presence of other astrocyte markers glial fibrillary acidic protein and S-100 protein in the UC-11MG cells. The steady-state ion transport properties of Na+, Cl-, and K+ were also characterized in these cells, and the rates of efflux were found to be similar to those in other astrocytes, with the major difference being the presence of a second kinetic compartment in the UC-11MG cells. From this work, we conclude that the UC-11MG cell line displays prominent features associated with differentiated astrocytes, and may provide an excellent model system for the study of human astrocytes.