Electrophysiological characterization of a novel human neuroectodermal cell line

Introduction We report the basic electrophysiological features of a novel human cell line, designated as TB, derived from the cerebrospinal fluid (CSF) of a patient with clinical diagnosis of primary leptomeningeal melanomatosis. These cells were previously isolated and characterized with an immunological and ultrastructural analysis [1]. TB cells have neuroectodermal origin, but they are able to morphologically differentiate if treated with retinoic acid (RA). In particular, RA, but not nerve growth factor (NGF), induces morphological differentiation towards a neuronal phenotype [1]. Aims Aim of this work is to verify if TB cells show electrophysiological neuronal-like activity before and after RA treatment [2] and to evaluate if the electrophysiological properties change together with the morphology. Material and method TB cells were seeded in 6-wells plates on 8 mm round cover glasses using DMEM medium supplemented with 15% FBS and 1% pen/strep. After 24 hours, cells were treated with 10 Â?M RA to induce the differentiation. TB cells without RA were also prepared (control). We used whole cell patch clamp to test, on both differentiated and undifferentiated cells, at different time points (1-7 days), the resting potential, the inward and outward currents and the ability to emit spikes if appropriately stimulated. Results Our results show that resting potential (VR) of TB cells, such as other undifferentiated cells [2], is -45+/-5 mV before treatment, which is more positive than expected in a neuronal-type cell. The inward current, responsible for the depolarizing phase of the spike, is very small (50 +/-15 pA) and, consequently, spikes do not occur . Although the outward current is high, it is still lower than the one produced in the hyperpolarizing phase of the neuronal spike. RA treatment up to 7 days is not sufficient to generate a complete neuronal like activity, although it shows a significant increase of both inward and outward currents. Discussion Our preliminary results show that RA-induced transformation prompts functional changes that, although not sufficient to generate neuronal like activity, go in the direction of a neuronal phenotype. Conclusions TB cells do not show neuronal-like basic activity. RA treatment up to 7 days drives the cells morphologically in the direction of the neuronal phenotype but they remain functionally immature.