Electrophysiological properties of human induced pluripotent stem cells

Abstract

Human embryonic stem cells (hESCs) can self-renew while maintaining their pluripotency. Direct reprogramming of adult somatic cells to induced pluripotent stem cells (iPSCs) has been reported. Although hESCs and human iPSCs have been shown to share a number of similarities, such basic properties as the electrophysiology of iPSCs have not been explored. Previously, we reported that several specialized ion channels are functionally expressed in hESCs. Using transcriptomic analyses as a guide, we observed tetraethylammonium (TEA)-sensitive (IC50 = 3.3 ± 2.7 mM) delayed rectifier K+ currents ( IKDR) in 105 of 110 single iPSCs (15.4 ± 0.9 pF). IKDR in iPSCs displayed a current density of 7.6 ± 3.8 pA/pF at +40 mV. The voltage for 50% activation ( V1/2) was −7.9 ± 2.0 mV, slope factor k = 9.1 ± 1.5. However, Ca2+-activated K+ current ( IKCa), hyperpolarization-activated pacemaker current ( If), and voltage-gated sodium channel (NaV) and voltage-gated calcium channel (CaV) currents could not be measured. TEA inhibited iPSC proliferation (EC50 = 7.8 ± 1.2 mM) and viability (EC50 = 5.5 ± 1.0 mM). By contrast, 4-aminopyridine (4-AP) inhibited viability (EC50 = 4.5 ± 0.5 mM) but had less effect on proliferation (EC50 = 0.9 ± 0.5 mM). Cell cycle analysis further revealed that K+ channel blockers inhibited proliferation primarily by arresting the mitotic phase. TEA and 4-AP had no effect on iPSC differentiation as gauged by ability to form embryoid bodies and expression of germ layer markers after induction of differentiation. Neither iberiotoxin nor apamin had any function effects, consistent with the lack of IKCa in iPSCs. Our results reveal further differences and similarities between human iPSCs and hESCs. A better understanding of the basic biology of iPSCs may facilitate their ultimate clinical application.

SK4 Ca 2+ activated K + channel is a critical player in cardiac pacemaker derived from human embryonic stem cells

“…Embryonic stem cells differentiate in vitro into spontaneously beating multicellular cardiomyocyte clusters within embryoid bodies (EBs), while recapitulating developmental stages of embryonic cardiomyogenesis (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27). Thus, human embryonic stem cell-derived cardiomyocytes (hESC-CMs) may provide insights into the pacemaker mechanisms of embryonic cardiac development.…”

Single Mechanosensitive and Ca2+-Sensitive Channel Currents Recorded from Mouse and Human Embryonic Stem Cells

“…In particular, several voltagegated currents, including depolarization-activated K + (Kv), hyperpolarization-activated cation (HCN), and T-type Ca 2+ currents, have been measured in one or both species of ESCs (Wang et al, 2005;Sartiani et al, 2007;Jiang et al, 2010Kleger et al, 2010Lau et al, 2011;Ng et al, 2010;Rodriguez-Gomez et al, 2012). In comparative studies, significantly larger (5 fold)…”

“…Kv currents were recorded in hESC compared with mESC (Wang et al, 2005; but see also Jiang et al, 2010) but for HCN currents, they were detected in mESCs but not in hESCs. Our 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 4...…”

“…By transducing membrane stretch into changes in membrane potential and/or changes in intracellular [Ca 2+ ], MS channel activity can influence a variety of downstream signaling pathways that regulate cell proliferation and differentiation (Machaca et al, 2007;Kapur et al, 2007;Sundelacruz et al, 2009;Apati et al, 20 12). However, although previous studies using whole cell patch clamp and/or Ca 2+ imaging techniques have identified voltage-gated and receptor-gated channels in ESCs (Yangagida et al, 2004;Wang et al, 2005;Jiang et al, 2010;Ng et al, 2010;Rodriguez-Gomez et al, 2012) there have been no 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 reports regarding the expression of MS channels. To address this deficiency we use cellattached and inside-our patch clamp recording to determine if mouse and human ESCs express MS channels.…”

Maintaining Embryonic Stem Cells and Induced Pluripotent Stem Cells

“…Patient-specific pluripotent cell lines may provide a limitless source for human cell therapeutic application. However, although human ES cells and human iPS cells have been shown to share a number of similarities, there are still differences electrophysiology properties between human ES cells and human iPS cells (Jiang et al, 2010). It has been showed that foreign genes were silenced or removed after reprogramming, but those approaches have low reprogramming efficiency, and either leave residual vector sequences, or require tedious steps.…”