Open AccessAdvancing physiological maturation in human induced pluripotent stem cell‐derived cardiac muscle by gene editing an inducible adult troponin isoform switch
Author(s) -
Wheelwright Matthew,
Mikkila Jennifer,
Bedada Fikru B.,
Mandegar Mohammad A.,
Thompson Brian R.,
Metzger Joseph M.
Publication year - 2020
Publication title -
stem cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.159
H-Index - 229
eISSN - 1549-4918
pISSN - 1066-5099
DOI - 10.1002/stem.3235
Subject(s) - induced pluripotent stem cell , biology , sarcomere , troponin i , microbiology and biotechnology , gene isoform , myosin , myocyte , cardiac muscle , embryonic stem cell , medicine , anatomy , gene , biochemistry , myocardial infarction
Advancing maturation of stem cell‐derived cardiac muscle represents a major barrier to progress in cardiac regenerative medicine. Cardiac muscle maturation involves a myriad of gene, protein, and cell‐based transitions, spanning across all aspects of cardiac muscle form and function. We focused here on a key developmentally controlled transition in the cardiac sarcomere, the functional unit of the heart. Using a gene‐editing platform, human induced pluripotent stem cell (hiPSCs) were engineered with a drug‐inducible expression cassette driving the adult cardiac troponin I (cTnI) regulatory isoform, a transition shown to be a rate‐limiting step in advancing sarcomeric maturation of hiPSC cardiac muscle (hiPSC‐CM) toward the adult state. Findings show that induction of the adult cTnI isoform resulted in the physiological acquisition of adult‐like cardiac contractile function in hiPSC‐CMs in vitro. Specifically, cTnI induction accelerated relaxation kinetics at baseline conditions, a result independent of alterations in the kinetics of the intracellular Ca 2+ transient. In comparison, isogenic unedited hiPSC‐CMs had no cTnI induction and no change in relaxation function. Temporal control of adult cTnI isoform induction did not alter other developmentally regulated sarcomere transitions, including myosin heavy chain isoform expression, nor did it affect expression of SERCA2a or phospholamban. Taken together, precision genetic targeting of sarcomere maturation via inducible TnI isoform switching enables physiologically relevant adult myocardium‐like contractile adaptations that are essential for beat‐to‐beat modulation of adult human heart performance. These findings have relevance to hiPSC‐CM structure‐function and drug‐discovery studies in vitro, as well as for potential future clinical applications of physiologically optimized hiPSC‐CM in cardiac regeneration/repair.