Personalized in vitro models reveal functional impact of a KCNH2 mutation and enable drug screening in LQTS2

Background Long QT syndrome (LQTS) is clinically associated with recurrent ventricular tachycardia and sudden cardiac death. Mutations in KCNH2 , which encodes the pore-forming potassium channel subunit hERG (Kv11.1), are associated with LQTS type 2. Objective We aimed to investigate the pathogenicity and personalized therapy for a patient with LQTS2 carrying a novel KCNH2 heterozygous mutation F431L. Methods To evaluate the expression and function of the channel protein, we conducted immunoblotting and whole-cell patch-clamp recordings. Additionally, patient-specific human-induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) were combined with a heart-on-chip platform to validate the pathogenicity of this heterozygous variant and to investigate the pharmacological candidates for phenotypic rescue. Results In HEK293 cells overexpressing the mutant KCNH2 , a significant reduction in hERG membrane abundance was observed. The heterozygous variant led to decreased current density and alterations in voltage-dependent activation (positively shifted) and inactivation (negatively shifted) compared to wild-type. Correspondingly, patient-specific iPSC-CMs harboring the heterozygous KCNH2 F431L mutation displayed reduced current density and prolonged action potential duration. Moreover, LQTS2 patient-specific engineered cardiac tissues replicated the disease phenotype with extended field potential duration. Drug screening on the heart-on-chip platform indicated the potential therapeutic efficacy of IKs channel agonists ML277 and the proteasome inhibitor MG101. Conclusion The F431L mutation in KCNH2 was pathogenic, characterized by both channel instability and functional impairments. Our study also highlighted the feasibility of using a patient-specific micro-physiological system for individualized treatment in ion-channel diseases.