Functional expression of ion channels in mesenchymal stem cells derived from umbilical cord vein

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 (I-to), and a delayed rectifier K+ current (IKDr). IKCa and IKDR were totally suppressed by tetraethylammonium, and IKCa was sensitive to a specific blocker, iberiotoxin. I-to was inhibited by 4-aminopyridine. Another type of inward rectifier K+ current (K-ir) was also detected in approximately 5% of hUC-MSCs. Elevation of external potassium ion concentration increased the K-ir current amplitude and positively shifted its reversal potential. In addition, inward Na+ current (I-Na) was found in these cells (similar to 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, I-to, I-Na, and K-ir, are expressed in hUC-MSCs.