Simultaneous recordings of action potentials and calcium transients from human induced pluripotent stem cell derived cardiomyocytes.

Chandra Prajapati,Risto-Pekka Pölönen,Katriina Aalto-Setälä

doi:10.1242/bio.035030

Chandra Prajapati, Risto-Pekka Pölönen + Show 1 more

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https://doi.org/10.1242/bio.035030

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Journal: Biology open	Publication Date: Jan 1, 2018
Citations: 18	License type: CC BY 3.0

Affiliation: Tampere University, Tampere University Hospital

Abstract

ABSTRACTHuman induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) offer a unique in vitro platform to study cardiac diseases, as they recapitulate many disease phenotypes. The membrane potential (Vm) and intracellular calcium (Ca2+) transient (CaT) are usually investigated separately, because incorporating different techniques to acquire both aspects concurrently is challenging. In this study, we recorded Vm and CaT simultaneously to understand the interrelation between these parameters in hiPSC-CMs. For this, we used a conventional patch clamp technique to record Vm, and synchronized this with a Ca2+ imaging system to acquire CaT from same hiPSC-CMs. Our results revealed that the CaT at 90% decay (CaT90) was longer than action potential (AP) duration at 90% repolarization (APD90). In addition, there was also a strong positive correlation between the different parameters of CaT and AP. The majority of delayed after depolarizations (DADs) observed in the Vm recording were also characterized by elevations in the intracellular Ca2+ level, but in some cases no abnormalities were observed in CaT. However, simultaneous fluctuations in CaT were always observed during early after depolarizations (EADs) in Vm. In summary, simultaneous recording of Vm and CaT broadens the understanding of the interrelation between Vm and CaT and could be used to elucidate the mechanisms underlying arrhythmia in cardiac disease condition.

Highlights

Immunostaining experiments were performed to confirm the presence of different cardiac proteins in human induced pluripotent stem cells (hiPSCs)-CMs
Immunostainings of hiPSC-CMs showed the positive staining of cardiac troponin T, CaV1.2 and cardiac ryanodine receptor (RyR2) (Fig. 1)
These immunostaining images show the homogenous distribution of ICa,L and RyR2 in hiPSC-CMs

Summary

Introduction

The discovery of human induced pluripotent stem cells (hiPSCs) (Takahashi et al, 2007) from somatic cells and their ability to differentiate into cardiomyocytes (CMs) (hiPSC-CMs) provides a robust platform to study genetic cardiac diseases (Kujala et al, 2012; Lahti et al, 2012; Kiviaho et al, 2015; Penttinen et al, 2015; Ojala et al, 2016; Kuusela et al, 2017; Prajapati et al, 2018; Itzhaki et al, 2012; Ma et al, 2015; Spencer et al, 2014) and for drug screening (Liang et al, 2013). Received 16 April 2018; Accepted 13 June 2018 cardiac ion channels (Lee et al, 2016), Ca2+ cycling components (Itzhaki et al, 2011) and adrenergic receptors (Földes et al, 2014) These hiPSC-CMs closely mimic cardiac functionality and have already recapitulated many genetic cardiac diseases such as LQT1 (Kiviaho et al, 2015; Kuusela et al, 2017; Ma et al, 2015), LQT2 (Lahti et al, 2012; Spencer et al, 2014), CPVT (Kujala et al, 2012; Itzhaki et al, 2012; Penttinen et al, 2015; Pölönen et al, 2018; Ahola et al, 2017) and HCM (Ojala et al, 2016; Prajapati et al, 2018; Földes et al, 2014; Lan et al, 2013; Han et al, 2014). The cell membrane is repolarized by several repolarizing potassium currents and Ca2+ is reloaded into SR via SR Ca2+ ATPase. (Kane et al, 2015)

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