Characterization of Ionic Currents in Human Mesenchymal Stem Cells from Bone Marrow

Abstract

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 Ca2+-activated K+ channel (IKCa) blocker iberiotoxin, a transient outward K+ current (Ito) suppressed by 4-aminopyridine (4-AP), and a delayed rectifier K+ current (IKDR)-like ether-à-go-go (eag) K+ channel. In addition, tetrodotoxin-sensitive sodium current (INa.TTX) and nifedipine-sensitive L-type Ca2+ current (ICa.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 IKCa, Kv4.2 and Kv1.4 for Ito, heag1 for IKDR, hNE-Na for INa.TTX, and CACNAIC for I Ca.L. These results demonstrate that multiple functional ion channel currents-that is, IKca, Ito heag1, INa.TTX, and ICa.L-are expressed in hMSCs from bone marrow.