Phospholamban as a Crucial Determinant of the Inotropic Response of Human Pluripotent Stem Cell–Derived Ventricular Cardiomyocytes and Engineered 3-Dimensional Tissue Constructs. (February 2015)

• Record Type: Journal Article
• Authors: Chen, Gaopeng; Li, Sen; Karakikes, Ioannis; Ren, Lihuan; Zi-Ying Chow, Maggie; Chopra, Anant; Keung, Wendy; Yan, Bin; Chan, Camie W.Y.; Costa, Kevin D.; Kong, Chi-Wing; Hajjar, Roger J.; Chen, Christopher S.; Li, Ronald A.
• Is Part Of: Circulation. Volume 8:Number 1(2015)
• Publication Date: 2015-02
• Subjects: Arrhythmia -- Periodicals; Heart -- Electric properties -- Periodicals; 616.128
• DOI: 10.1161/CIRCEP.114.002049
• Languages: English
• ISSNs: 1941-3149

Abstract

<abstract> <title> <x xml:space="preserve">Abstract</x> </title> <sec> <title>Background—</title> <p>Human (h) embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) serve as a potential unlimited ex vivo source of cardiomyocytes (CMs). However, a well-accepted roadblock has been their immature phenotype. hESC/iPSC-derived ventricular (v) CMs and their engineered cardiac microtissues (hvCMTs) similarly displayed positive chronotropic but null inotropic responses to β-adrenergic stimulation. Given that phospholamban (PLB) is robustly present in adult but poorly expressed in hESC/iPSC-vCMs and its defined biological role in β-adrenergic signaling, we investigated the functional consequences of PLB expression in hESC/iPSC-vCMs and hvCMTs.</p> </sec> <sec> <title>Methods and Results—</title> <p>First, we confirmed that PLB protein was differentially expressed in hESC (HES2, H9)- and iPSC-derived and adult vCMs. We then transduced hES2-vCMs with the recombinant adenoviruses (Ad) Ad-PLB or Ad-S16E-PLB to overexpress wild-type PLB or the pseudophosphorylated point–mutated variant, respectively. As anticipated from the inhibitory effect of unphosphorylated PLB on sarco/endoplasmic reticulum Ca<sup>2+</sup>-ATPase, Ad-PLB transduction significantly attenuated electrically evoked Ca<sup>2+</sup> transient amplitude and prolonged the 50% decay time. Importantly, Ad-PLB–transduced hES2-vCMs uniquely responded to isoproterenol. Ad-S16E-PLB–transduced hES2-vCMs displayed an intermediate phenotype. The same trends were observed with H9- and iPSC-vCMs. Directionally, similar results were also seen with Ad-PLB–transduced and Ad-S16E–transduced hvCMTs. However, Ad-PLB altered neither the global transcriptome nor I<sub>Ca, L</sub>, implicating a PLB-specific effect.</p> </sec> <sec> <title>Conclusions—</title> <p>Engineered upregulation of PLB expression in hESC/iPSC-vCMs restores a positive inotropic response to β-adrenergic stimulation. These results not only provide a better mechanistic understanding of the immaturity of hESC/iPSC-vCMs but will also lead to improved disease models and transplantable prototypes with adult-like physiological responses.</p> </sec> </abstract>