Abstract 13360: Modeling Pompe and Danon Cardiomyopathies With Human Induced Pluripotent Stem Cells

IntroductionThe glycogen storage diseases Pompe and Danon diseases are skeletal and cardiac myopathies caused by deficiency of the glycogen-degrading lysosomal enzyme acid alpha-glucosidase (GAA) and Lysosomal-Associated Membrane Protein 2, respectively.Aims(1) To test the hypothesis that patient-specific human induced pluripotent stem cells (hiPSCs) can be used to model Pompe and Danon disease mechanisms and treatments. (2) To evaluate the role of abnormal autophagy in Pompe and Danon pathophysiology. (3) To assess Pompe and Danon contractile properties in a hiPSC-based 3D engineered cardiac-tissue model.Methods and ResultsPatient-specific hiPSCs were generated from an infantile Pompe patient and an adolescent Danon patient and differentiated into cardiomyocytes (hiPSC-CMs). Electron microscopy, immunostainings and protein electrophoresis revealed lysosome and autophagosome accumulation in both diseased cell lines. Pompe hiPSC-CMs presented with more progressive lysosomal pathology and intracellular damage compared to Danon cells. Immunostaining analysis demonstrated larger cell area of Danon hiPSC-CMs relative to control. Treatment with recombinant human GAA reversed pathological lysosomal glycogen storage in Pompe hiPSC-CMs but failed to clear the abnormal autophagic buildup. Calcium imaging displayed calcium-handling irregularities in Pompe hiPSC-CMs and slower calcium transient kinetics in Danon cells. Finally, contractile analysis of 3D engineered heart tissues revealed a trend of diminished force in the Pompe specimens relative to controls, whereas Danon tissues produced similar forces as controls.ConclusionsPatient-specific hiPSC-CMs recapitulated the phenotype of Pompe and Danon diseases in-vitro and displayed the underlying lysosomal and autophagosomal pathology. These findings suggest a mechanistic role for abnormal autophagy in Pompe cardiomyopathy. The generated model allowed evaluating patient-specific response to enzyme replacement therapy and demonstrated its benefits and potential limitation. Finally, a 3D tissue model was established which revealed hypertrophy-compatible features of Danon disease and abnormal contractility features of Pompe disease.