技术资料

AIMS Current treatment for congenital long QT syndrome Type 2 (cLQTS2),an electrical disorder that increases the risk of life-threatening cardiac arrhythmias,is aimed at reducing the incidence of arrhythmia triggers (beta-blockers) or terminating the arrhythmia after onset (implantable cardioverter-defibrillator). An alternative strategy is to target the underlying disease mechanism,which is reduced rapid delayed rectifier current (IKr) passed by Kv11.1 channels. Small molecule activators of Kv11.1 have been identified but the extent to which these can restore normal cardiac signalling in cLQTS2 backgrounds remains unclear. Here,we examined the ability of ICA-105574,an activator of Kv11.1 that impairs transition to the inactivated state,to restore function to heterozygous Kv11.1 channels containing either inactivation enhanced (T618S,N633S) or expression deficient (A422T) mutations. METHODS AND RESULTS ICA-105574 effectively restored Kv11.1 current from heterozygous inactivation enhanced or expression defective mutant channels in heterologous expression systems. In a human-induced pluripotent stem cell-derived cardiomyocyte (hiPSC-CM) model of cLQTS2 containing the expression defective Kv11.1 mutant A422T,cardiac repolarization,estimated from the duration of calcium transients in isolated cells and the rate corrected field potential duration (FPDc) in culture monolayers of cells,was significantly prolonged. The Kv11.1 activator ICA-105574 was able to reverse the prolonged repolarization in a concentration-dependent manner. However,at higher doses,ICA-105574 produced a shortening of the FPDc compared to controls. In vitro and in silico analysis suggests that this overcorrection occurs as a result of a temporal redistribution of the peak IKr to much earlier in the plateau phase of the action potential,which results in early repolarization. CONCLUSION Kv11.1 activators,which target the primary disease mechanism,provide a possible treatment option for cLQTS2,with the caveat that there may be a risk of overcorrection that could itself be pro-arrhythmic. View Publication

Induced pluripotent stem cells (iPSC) derived from healthy individuals are important controls for disease-modeling studies. Here we apply precision health to create a high-quality resource of control iPSCs. Footprint-free lines were reprogrammed from four volunteers of the Personal Genome Project Canada (PGPC). Multilineage-directed differentiation efficiently produced functional cortical neurons,cardiomyocytes and hepatocytes. Pilot users demonstrated versatility by generating kidney organoids,T lymphocytes,and sensory neurons. A frameshift knockout was introduced into MYBPC3 and these cardiomyocytes exhibited the expected hypertrophic phenotype. Whole-genome sequencing-based annotation of PGPC lines revealed on average 20 coding variants. Importantly,nearly all annotated PGPC and HipSci lines harbored at least one pre-existing or acquired variant with cardiac,neurological,or other disease associations. Overall,PGPC lines were efficiently differentiated by multiple users into cells from six tissues for disease modeling,and variant-preferred healthy control lines were identified for specific disease settings. View Publication