Autonomous beating rate adaptation in human stem cell-derived cardiomyocytes

Abstract

The therapeutic success of human stem cell-derived cardiomyocytes critically depends on their ability to respond to and integrate with the surrounding electromechanical environment. Currently, the immaturity of human cardiomyocytes derived from stem cells limits their utility for regenerative medicine and biological research. We hypothesize that biomimetic electrical signals regulate the intrinsic beating properties of cardiomyocytes. Here we show that electrical conditioning of human stem cell-derived cardiomyocytes in three-dimensional culture promotes cardiomyocyte maturation, alters their automaticity and enhances connexin expression. Cardiomyocytes adapt their autonomous beating rate to the frequency at which they were stimulated, an effect mediated by the emergence of a rapidly depolarizing cell population, and the expression of hERG. This rate-adaptive behaviour is long lasting and transferable to the surrounding cardiomyocytes. Thus, electrical conditioning may be used to promote cardiomyocyte maturation and establish their automaticity, with implications for cell-based reduction of arrhythmia during heart regeneration.

Inspiration from heart development: Biomimetic development of functional human cardiac organoids

“…This suggested that the developing stage ratio provided a favorable microenvironment for hiPSC-CM development and supported the developmental basis for cardiac organoid fabrication. This finding is consistent with previous engineered findings showing that cardiac constructs containing a majority of cardiomyocytes of the construct supports increased hiPSC-CM functions (15, 17, 22, 48). The developing stage cell ratio for cardiac organoids was used for the remainder of the experiments.…”

Advanced maturation of human cardiac tissue grown from pluripotent stem cells

“…The ultrastructural machinery for contraction/relaxation was confirmed by the positioning of t-tubules in proximity to cardiac calcium pump SERCA2A/ ATP2A2 and sodium-calcium exchanger NCX1/ SLC8A1 . Consistently, transcription of the genes responsible for clearing cytosolic calcium ( ATP2A2 and SLC8A1 17 ) increased over time and the sequestration and extrusion of calcium became faster, enabling the iPS-CMs to relax and respond to contractile triggers. Blocking Ca V 1.2 by nifedipine or verapamil gradually reduced calcium transients in a training-dependent manner, while the response to caffeine indicated that only the early/intensity tissues had functional intracellular calcium stores.…”

“…Human iPS-CMs can be matured by long-term culture, electrical, hydrodynamic and mechanical stimulation 8,9,15–17,31 . Recent studies indicate that the in vitro culture may not follow the developmental paradigm: high stimulation frequencies benefit maturation in vitro 9 , while the native heart beats more slowly following birth 5,13 .…”

Distilling complexity to advance cardiac tissue engineering

“…An alternative strategy for cardiac maturation is electrical stimulation, which was shown to improve calcium handling and electrophysiological properties of iPSC-CMs (10) and to regulate their beating rate (11). However, the evidence that mechanical and/or electrical stimulation can lead to ultrastructural and functional hallmarks of adult heart muscle: sarcomeres with dense mitochondria, T-tubules and M-lines, and a positive force-frequency relationship (Bowditch phenomenon) is yet to be published.…”