POTASSIUM CHANNEL CURRENTS IN RAT MESENCHYMAL STEM CELLS AND THEIR POSSIBLE ROLES IN CELL PROLIFERATION

SUMMARY 1 Mesenchymal stem cells (MSC) have shown considerable promise for the regeneration and repair of damaged tissue. However, the electrophysiological properties of K+ channels in MSC are not well established and little is known about the role of K+ channels in the regulation of MSC proliferation. 2 We detected three distinct outward currents in MSC: (i) a delayed rectifier current (IKDR); (ii) a Ca2+‐activated K+ current (IKCa); and (iii) a transient outward K+ current (Ito). All three were present either alone or in combination in almost all cells (90%) investigated. However, 10% of cells did not express a functional current within physiological potentials. 3 Reverse transcription–polymerase chain reaction was used to identify mRNA associated with functional ionic currents. Kv1.2 and Kv2.1 were associated with IKDR; Slo and KCNN4 were associated with IKCa; and Kv1.4 and Kv4.3 were associated with Ito. 4 The Kv channel blockers amiodarone, tetraethylammonium and verapamil, as well as increased extracellular K+ levels, inhibited proliferation of cultured MSC. 5 In MSC treated with Kv channel blockers or an increased extracellular concentration of K+, the proportion of cells in the S phase decreased significantly and the proportion of cells in the G0/G1 phase tended to increase, indicating that the cells were prevented from entering the S phase of the cell cycle. 6 Our findings suggest that rat MSC heterogeneously express distinct types of K+ current, of which the voltage‐gated IKDR‐like K+ current is most common. Kv channel activity modulates the progression of the cell cycle, affecting the proliferation of MSC.