Combinatorial Treatment of Human Cardiac Engineered Tissues With Biomimetic Cues Induces Functional Maturation as Revealed by Optical Mapping of Action Potentials and Calcium Transients

Andy On-Tik Wong; Nicodemus Wong; Lin Geng; Maggie Zi-Ying Chow; Eugene K Lee; Hongkai Wu; Michelle Khine; Chi-Wing Kong; Kevin D Costa; Wendy Keung; Yiu-Fai Cheung; Ronald A Li

doi:10.3389/fphys.2020.00165

Combinatorial Treatment of Human Cardiac Engineered Tissues With Biomimetic Cues Induces Functional Maturation as Revealed by Optical Mapping of Action Potentials and Calcium Transients

Front Physiol. 2020 Mar 12:11:165. doi: 10.3389/fphys.2020.00165. eCollection 2020.

Authors

Andy On-Tik Wong^{1

2}, Nicodemus Wong^{2

3}, Lin Geng^{2

3}, Maggie Zi-Ying Chow², Eugene K Lee⁴, Hongkai Wu⁵, Michelle Khine⁴, Chi-Wing Kong², Kevin D Costa⁶, Wendy Keung^{2

3}, Yiu-Fai Cheung¹, Ronald A Li^{1

3

7}

Affiliations

¹ Department of Paediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pok Fu Lam, Hong Kong.
² Stem Cell and Regenerative Medicine Consortium, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pok Fu Lam, Hong Kong.
³ Dr. Li Dak-Sum Research Centre, The University of Hong Kong - Karolinska Institutet Collaboration in Regenerative Medicine, The University of Hong Kong, Pok Fu Lam, Hong Kong.
⁴ Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, United States.
⁵ Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Kowloon, Hong Kong.
⁶ Icahn School of Medicine at Mount Sinai, Manhattan, NY, United States.
⁷ Ming-Wai Lau Centre for Reparative Medicine, Karolinska Institutet, Stockholm, Sweden.

Abstract

Although biomimetic stimuli, such as microgroove-induced alignment (μ), triiodothyronine (T3) induction, and electrical conditioning (EC), have been reported to promote maturation of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs), a systematic examination of their combinatorial effects on engineered cardiac tissue constructs and the underlying molecular pathways has not been reported. Herein, human embryonic stem cell-derived ventricular cardiomyocytes (hESC-VCMs) were used to generate a micro-patterned human ventricular cardiac anisotropic sheets (hvCAS) for studying the physiological effects of combinatorial treatments by a range of functional, calcium (Ca²⁺)-handling, and molecular analyses. High-resolution optical mapping showed that combined μ-T3-EC treatment of hvCAS increased the conduction velocity, anisotropic ratio, and proportion of mature quiescent-yet-excitable preparations by 2. 3-, 1. 8-, and 5-fold (>70%), respectively. Such electrophysiological changes could be attributed to an increase in inward sodium current density and a decrease in funny current densities, which is consistent with the observed up- and downregulated SCN1B and HCN2/4 transcripts, respectively. Furthermore, Ca²⁺-handling transcripts encoding for phospholamban (PLN) and sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA) were upregulated, and this led to faster upstroke and decay kinetics of Ca²⁺-transients. RNA-sequencing and pathway mapping of T3-EC-treated hvCAS revealed that the TGF-β signaling was downregulated; the TGF-β receptor agonist and antagonist TGF-β1 and SB431542 partially reversed T3-EC induced quiescence and reduced spontaneous contractions, respectively. Taken together, we concluded that topographical cues alone primed cardiac tissue constructs for augmented electrophysiological and calcium handling by T3-EC. Not only do these studies improve our understanding of hPSC-CM biology, but the orchestration of these pro-maturational factors also improves the use of engineered cardiac tissues for in vitro drug screening and disease modeling.

Keywords: action potential; calcium handling; electrical conditioning; maturation; tissue engineering; triiodothyronine.