Cardiology Division, Department of Medicine, University of Hong Kong, Hong Kong.
Am J Physiol Cell Physiol. 2012 Jul 15;303(2):C115-25. doi: 10.1152/ajpcell.00326.2011. Epub 2012 Feb 22.
The successful generation of a high yield of mesenchymal stem cells (MSCs) from human induced pluripotent stem cells (iPSCs) may represent an unlimited cell source with superior therapeutic benefits for tissue regeneration to bone marrow (BM)-derived MSCs. We investigated whether the differential expression of ion channels in iPSC-MSCs was responsible for their higher proliferation capacity than BM-MSCs. The expression of ion channels for K(+), Na(+), Ca(2+), and Cl(-) was examined by RT-PCR. The electrophysiological properties of iPSC-MSCs and BM-MSCs were then compared by patch-clamp experiments to verify their functional roles. Significant mRNA expression of ion channel genes including KCa1.1, KCa3.1, KCNH1, Kir2.1, SCN9A, CACNA1C, and Clcn3 was observed in both human iPSC-MSCs and BM-MSCs, whereas Kir2.2 and Kir2.3 were only detected in human iPSC-MSCs. Five types of currents [big-conductance Ca(2+)-activated K(+) current (BK(Ca)), delayed rectifier K(+) current (IK(DR)), inwardly rectifying K(+) current (I(Kir)), Ca(2+)-activated K(+) current (IK(Ca)), and chloride current (I(Cl))] were found in iPSC-MSCs (83%, 47%, 11%, 5%, and 4%, respectively) but only four of them (BK(Ca), IK(DR), I(Kir), and IK(Ca)) were identified in BM-MSCs (76%, 25%, 22%, and 11%, respectively). Cell proliferation was examined with MTT or bromodeoxyuridine assay, and doubling times were 2.66 and 3.72 days for iPSC-MSCs and BM-MSCs, respectively, showing a 1.4-fold discrepancy. Blockade of IK(DR) with short hairpin RNA or human ether-à-go-go 1 (hEAG1) channel blockers, 4-AP and astemizole, significantly reduced the rate of proliferation of human iPSC-MSCs. These treatments also decreased the rate of proliferation of human BM-MSCs albeit to a lesser extent. These findings demonstrate that the hEAG1 channel plays a crucial role in controlling the proliferation rate of human iPSC-MSCs and to a lesser extent in BM-MSCs.
从人类诱导多能干细胞（iPSC）中成功产生高产量的间充质干细胞（MSC）可能代表着一种无限的细胞来源，与骨髓（BM）来源的 MSC 相比，具有更好的组织再生治疗益处。我们研究了 iPSC-MSC 中离子通道的差异表达是否与其比 BM-MSC 更高的增殖能力有关。通过 RT-PCR 检查 K(+)、Na(+)、Ca(2+)和 Cl(-)离子通道的表达。然后通过膜片钳实验比较 iPSC-MSC 和 BM-MSC 的电生理特性，以验证它们的功能作用。在人 iPSC-MSC 和 BM-MSC 中均观察到离子通道基因包括 KCa1.1、KCa3.1、KCNH1、Kir2.1、SCN9A、CACNA1C 和 Clcn3 的显著 mRNA 表达，而 Kir2.2 和 Kir2.3 仅在人 iPSC-MSC 中检测到。在 iPSC-MSC 中发现了 5 种电流[大电导钙激活钾电流（BK(Ca)）、延迟整流钾电流（IK(DR)）、内向整流钾电流（I(Kir)）、钙激活钾电流（IK(Ca)）和氯离子电流（I(Cl)）]（分别为 83%、47%、11%、5%和 4%），但在 BM-MSC 中仅鉴定出其中 4 种（BK(Ca)、IK(DR)、I(Kir)和 IK(Ca)）（分别为 76%、25%、22%和 11%）。通过 MTT 或溴脱氧尿苷测定法检查细胞增殖，iPSC-MSC 和 BM-MSC 的倍增时间分别为 2.66 和 3.72 天，相差 1.4 倍。用短发夹 RNA 或人 ether-à-go-go 1（hEAG1）通道阻滞剂 4-AP 和阿替洛尔阻断 IK(DR)，显著降低了人 iPSC-MSC 的增殖率。这些治疗方法也降低了人 BM-MSC 的增殖率，但程度较小。这些发现表明，hEAG1 通道在控制人 iPSC-MSC 的增殖率方面起着至关重要的作用，在 BM-MSC 中也起着一定的作用。
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