iPS technology as a tool to investigate atrial fibrillation

Atrial fibrillation (AF) is the most common arrhythmic disorder in adults, characterized by rapid and irregular activation of the atria and loss of coordinated contraction thus resulting in reduced ventricular filling and blood stasis in the atria, and finally leading to heart failure and thromboembolic stroke. AF has traditionally been described as a multifactorial sporadic disease; however some hints about AF hereditability have recently been issued from epidemiological and population-based GWAS. Therefore in vitro AF models to identify the genetic basis and to characterize interactions of cells belonging to cardiovascular lineage are urgently needed. We began to characterize a familial group with continuous AF who were scheduled to undergo surgical ablation following failed pharmacological treatment. Screening for mutation of the most common genes associated to AF (KCNQ1, KCNH2, KCNE1, KCNE2, and SCN5A) did not show any modification. We are now in process of sequencing some other putative candidate (MiRP1, CAV3, and HCN4), but a more extensive analysis needs to be carried out. In order to provide a platform to model AF disease, primary cultures of dermal fibroblasts were established from all individuals. Cells were induced to pluripotency by retroviral infection with the classical set of factors OSKM. Then, 2-4 independent clones per individual of AF-specific induced pluripotent stem cells (iPSC) were isolated. We have begun to characterize their pluripotency by morphology and growth dynamics, alkaline phosphatase staining, expression of pluripotency associated transcription factors (OCT4, SOX2, NANOG, REX1), surface markers (SSEA3, SSEA4, TRA1-60, TRA1-81), and silencing of retroviral transgenes. Following the assessment of pluripotency, we aim to differentiate AF-derived iPSC into cells of the cardiovascular lineage, such as cardiomyocytes and endothelial cells. We believe that the model we are developing will help us in clarifying the molecular basis of AF