Patient-derived induced pluripotent stem cells differentiated cardiomyocytes as platform for disease modeling for X-linked dilated cardiomyopathy

Abstract

X-linked dilated cardiomyopathy (XLDCM) is a serious condition caused by abnormalities in the DMD gene (dystrophin gene). The affected patients did not have major skeletal weakness but presented with early signs of heart failure, and deteriorated quickly despite medical treatment resulting in early death. Currently there is no curative treatment and heart transplantation is often required. We study the pathomechanism of the DMD-associated XLDCM with mutation in the first exon-intron boundary, through examination of dystrophin isoforms expression and the functional characterization of the manifested cardiomyocytes generated from patient-derived induced pluripotent stem cells (IPSCs) compared to normal control. We generated integration-free IPSCs derived from the peripheral blood mononuclear cells (PBMCs) of our XLDCM patient with DMD c.31+1G>A intron 1 splice site mutation. A healthy donor was recruited as normal control. Pluripotency of iPSC clones was confirmed by immunofluorescent staining, RT-PCR and teratoma formation. Patient and control IPSC cell lines were maintained and differentiated into cardiomyocytes (CM) with in-house protocol. The CMs generated were pathologically and functionally characterized. The patient-derived iPSCs pluripotency was confirmed. Cardiomyocytes differentiated from the iPSCs of the patient and the normal control expressed cardiac-specific markers and displayed electrically induced calcium transients. Decreased expression of dystrophin isoforms is associated with high osmotic fragility to hypotonic stress and abnormal calcium handling in the patient-derived iPSCs differentiated CM, as compared with that from normal control. This XLDCM patient-derived IPSCs model serves as an effective disease platform to study disease mechanisms.