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Abstract P445: A Combinatorial Approach Comprehensively Improves The Maturation Of Human Induced Pluripotent Stem Cell Derived Atrial Cardiomyocytes


 Introduction:
 The limited success of pharmacological approaches to atrial fibrillation (
 AF
 ) is due to limitations of
 in vitro
 and
 in vivo
 models and inaccessibility of human atrial tissue. Patient-specific induced pluripotent stem cell-derived atrial cardiomyocytes (iPSC-aCMs) are a robust platform to model the heterogeneous myocardial substrate of AF, but their immaturity limits their fidelity.
 
 
 Objective:
 We hypothesized that a combinatorial approach of biochemical (triiodothyronine [
 T3
 ], insulin-like growth factor-1 [
 IGF-1
 ], and dexamethasone; collectively
 TID
 ), bioenergetic (fatty acids [
 FA
 ]), and electrical stimulation (
 ES
 ) will enhance electrophysiological (
 EP
 ), structural, and metabolic maturity of iPSC-
 a
 CMs.
 
 
 Methods:
 We assessed maturation with whole cell patch clamping, calcium transients, immunofluorescence (IF), Seahorse Analyzer, contractility assay, RT-PCR, Western Blotting, and RNA sequencing (RNAseq). Using a time series with RNAseq we identified signaling pathways and transcriptional regulation that drive EP, structural, and metabolic atrial development and compared iPSC-aCM maturity with human aCMs (haCMs) obtained from the same patient.
 
 
 Results:
 TID+FA+ES significantly improved structural organization and cell morphology (
 Fig. 1a
 ), enhanced membrane potential stability and improved depolarization (
 Fig. 1b
 ), improved Ca
 2+
 kinetics with faster and increased Ca
 2+
 release from sarcoplasmic reticulum (
 Fig. 1c
 ), and increased expression of Na
 +
 , Ca
 2+
 , and K
 +
 channels, markers of structural maturity, FA metabolism, and oxidative phosphorylation (
 Fig. 1d
 ). There was no difference in each parameter between TID+FA+ES iPSC-aCMs and haCMs from the same patient.
 
 
 Conclusion:
 Our optimized, combinatorial TID+FA+ES approach markedly enhanced EP, structural, and metabolic maturity of human iPSC-aCMs, which will be useful for elucidating the genetic basis of AF developing precision drug therapies.
 
 
 
