Characterization of ionic currents in human mesenchymal stem cells from bone marrow.

This study characterized functional ion channels in cultured undifferentiated human mesenchymal stem cells (hMSCs) from bone marrow with whole-cell patch clamp and reverse transcription polymerase chain reaction (RT-PCR) techniques. Three types of outward currents were found in hMSCs, including a noise-like rapidly activating outward current inhibited by the large conductance Ca(2+)-activated K(+) channel (I(KCa)) blocker iberiotoxin, a transient outward K(+) current (I(to)) suppressed by 4-aminopyridine (4-AP), and a delayed rectifier K(+) current (IK(DR))-like ether-à-go-go (eag) K(+) channel. In addition, tetrodotoxin-sensitive sodium current (I(Na.TTX)) and nifedipine-sensitive L-type Ca(2+) current (I(Ca.L)) were also detected in 29% and 15% hMSCs, respectively. Moreover, RT-PCR revealed the molecular evidence of high levels of mRNA for the functional ionic currents, including human MaxiK for I(KCa), Kv4.2 and Kv1.4 for I(to), heag1 for IK(DR), hNE-Na for I(Na.TTX), and CACNAIC for I(Ca.L). These results demonstrate that multiple functional ion channel currents--that is, I(KCa), I(to), heag1, I(Na.TTX), and I(Ca.L)--are expressed in hMSCs from bone marrow.