Ionic Channels in Human Stem Cells Derived from Pulp of Deciduous Teeth

Abstract

Pulp of deciduous teeth contains mesenchymal stem cells originated from neural crest. These cells can be differentiated into several phenotypes (neuronal cells, adipocytes and odontoblasts). Functional expression of voltage-dependent channels (Na+ and K+) by these cells was investigated with special interest on the role of channels for the phenotype and differentiation.Cells were obtained from deciduous teeth of children (5 to 8 year's old, protocol approved by local ethical committee). Harvested cells were maintained in DMEM:F12 medium, supplemented with fetal bovine serum. Currents were recorded in voltage clamp mode of patch-clamp technique, whole cell configuration. Amplitude and kinetics of currents induced by depolarizing pulses were analyzed. Expression of genes coding for channel proteins were identified by amplifying cDNAs, obtained by RT-PCR, with specific primers.In the cell population half showed current through Nav, TTX-sensitive isoforms. The most conspicuous gene expressed was SCN1A (Nav1.1). Less but significant was the expression of SCN3A (Nav1.3) and SCN5A (Nav1.5). The expression of Kv is more variable in cell population. In some cells Kv channels activate rapidly with noisy currents. Probably currents pass through KCa. In fact, the expression of the gene MaxiK is strong. Some cells show K+ current with fast activation and inactivation, resembling transient outward current. cDNA for isoform Kv4.3 was unequivocally detected.Although functional channels were not detected, RNA transcript of gene HCN2 was found.Regarding ion channels mesenchymal cells show phenotypic variability. The notorious regularity is the expression of Nav, associated to action potential firing. These cells seem committed to neuronal differentiation.