Abstract 12102: TNNI3-K183del Mutation in Dilated Cardiomyopathy Patient-Specific iPSC-Derived Cardiomyocytes Affects Structural Proteins and Ion Channels, Leading to Impair the Function of Cardiomyocytes

Background: One of the causes for Dilated cardiomyopathy (DCM) are thought to be genetic defect. One mutation, Lys183 del mutation of the TNNI3, is suggested to be associated with left ventricular systolic dysfunction and transition from hypertrophic cardiomyopathy to DCM. However, the precise disease mechanism is not fully understood. Because cardiomyocytes derived from induced pluripotent stem cells (hiPSC-CMs) possess many of the same characteristics as primary human CMs and can be generated in unlimited quantities from pluripotent cell sources, they are thought to be a promising research tools to model genetic cardiomyopathies. Therefore, we hypothesized that iPS-CMs with mutations in TNNI3 is useful for elucidating the pathological mechanism of DCM and examined the phenotype of iPS-CMs with mutations in TNNI3. Methods and Results: We generated iPSCs from the patient with Lys183 del mutation of the TNNI3, and simultaneously induced iPS-CMs. By immunofluorescence stain analysis, we identified well-formed parallel arrays of repeating sarcomeres in myofibrils from WT iPS-CMs. On the other hand, iPS-CMs with Lys183 del mutation of the TNNI3 had fewer myofibrils and abnormal, irregular sarcomeres. In addition, sarcomere length was shorter in iPS-CMs with mutation in TNNI3 than in WT iPS-CMs. By gene expression analysis, we identified that iPS-CMs with mutation in TNNI3 had lower expression of some molecules including structural proteins or ion channels than WT iPS-CM. Cell motion analysis revealed that WT iPS-CMs were synchronously beating in multi wells, whereas iPS-CMs with mutation in TNNI3 were not. In addition, contraction velocity (CV) and relaxation velocity (RV) were significantly lower in iPS-CMs with mutation in TNNI3 (CV; 4.98±0.05 μm/sec, RV; 4.01±0.01 μm/sec) compared with WT iPS-CM (CV; 14.25±0.03 μm/sec, RV; 7.04±0.03 μm/sec). Moreover, significant decrease in contraction deformation distance and relaxation deformation distance were observed in iPS-CMs with mutation in TNNI3 (0.96±0.004 μm, 0.91±0.01 μm, respectively), compared to WT iPS-CMs (2.56±0.004 μm, 2.18±0.008 μm, respectively). Conclusion: iPS-CMs with Lys183 del mutation of the TNNI3 showed the morphological and functional phenotypes of DCM at a cellular level.