Mesenchymal stem cells have the ability to renew and differentiate into various lineages of mesenchymal tissues. We used undifferentiated human mesenchymal-like stem cells from human umbilical cord vein (hUC-MSCs), a cell line which contains several mesenchymal cell markers. We characterized functional ion channels in cultured hUC-MSCs with whole-cell patch clamp and reverse transcription-polymerase chain reaction (RT-PCR). Three types of outward current were found in these cells: the Ca2+-activated K+ channel (IKCa), a transient outward K+ current (Ito), and a delayed rectifier K+ current (IKDR). IKCa and IKDR were totally suppressed by tetraethylammonium, and IKCa was sensitive to a specific blocker, iberiotoxin. Ito was inhibited by 4-aminopyridine. Another type of inward rectifier K+ current (Kir) was also detected in approximately 5% of hUC-MSCs. Elevation of external potassium ion concentration increased the Kir current amplitude and positively shifted its reversal potential. In addition, inward Na+ current (INa) was found in these cells (∼30%); the current was blocked by tetrodotoxin and verapamil. In the RT-PCR analysis, Kv1.1, Kv4.2, Kv1.4, Kir2.1, heag1, MaxiK, hNE-Na, and TWIK-1 were detected. These results suggested that multiple functional ion channel currents, IKCa, IKDR, Ito, INa, and Kir, are expressed in hUC-MSCs.
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