A preclinical model of Brugada syndrome using CRISPR Repair in human cardiomyocytes from induced pluripotent stem cells: plattform for drug screening

Aims: Gene variants the calcium channels have been associated with Brugada syndrome (BrS). The investigation of the human cellular phenotype and the use of drugs for BrS is still lacking. Methods and results: This study recruited cells from a BrS patient carrying a missense variant (c.425C>T/p.S142F) in CACNB2 with uncertain significance as well as from three healthy persons. Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) generated from skin biopsies of healthy persons and the BrS patient (BrS-hiPSC-CMs) as well as CRISPR/Cas9 corrected cells (isogenic control, site-variant corrected) were used. HiPSC-CMs from the BrS patient showed a significantly reduced L-type calcium channel current (ICa-L). The inactivation curve was shifted to a more positive potential and the recovery from inactivation was accelerated. The protein expression of CACNB2 from the BrS-patient was significantly decreased. Moreover, the correction of the CACNB2 site-variant rescued the changes. In addition, the peak sodium current was significantly reduced as compared with the controls consistent with the reduction of the amplitude and upstroke velocity of action potentials in BrS-hiPSC-CMs. Arrhythmia events were more frequently detected in BrS-hiPSC-CMs. In cells without arrhythmic events, carbachol induced the occurrence of arrhythmias with a higher chance in BrS-hiPSC-CMs than in healthy cells. Whereas ajmaline (sodium channel blocker) did not increase arrhythmic events, bisoprolol (beta-blocker) at low concentration and quinidine decreased arrhythmic events. Conclusions: The CACNB2 variant (c.425C>T/p.S142F) causes a loss-of-function of L-type calcium channels and is pathogenic for this type of BrS. Bisoprolol and quinidine may be effective for treating BrS with this variant.