Background/aims: Ventricular septal defects (VSDs) are one of the most common types of congenital heart malformations. Volume overload resulting from large VSDs can lead to heart failure (HF) and constitutes a major cause of pediatric HF with a series of often-fatal consequences. The etiology of VSD with HF is complex, and increasing evidence points toward a genetic basis. Indeed, we identified an L2483R mutation in the ryanodine receptor type 2 (RyR2) in a 2-month-old male patient with VSD with HF.
Methods: We generated integration-free induced pluripotent stem cells from urine samples (UiPSCs) of this patient using Sendai virus containing the Yamanaka factors and characterized these cells based on alkaline phosphatase activity, pluripotency marker expression, and teratoma formation. Then, we induced the derived UiPSCs to rapidly and efficiently differentiate into functional cardiomyocytes through temporal modulation of canonical Wnt signaling with small molecules. Real-time PCR and immunofluorescence were used to verify the expression of myocardium-specific markers in the differentiated cardiomyocytes. The ultrastructure of the derived myocardial cells was further analyzed by using transmission electron microscopy.
Results: The established UiPSC lines were positive for alkaline phosphatase activity, retained the RyR2 mutation, expressed pluripotency markers, and displayed differentiation potential to three germ layers in vivo. The UiPSC-derived cells showed hallmarks of cardiomyocytes, including spontaneous contraction and strong expression of cardiac-specific proteins and genes. However, compared with cardiomyocytes derived from H9 cells, they had a higher level of autophagy, implying that autophagy may play an important role in the development of VSD with HF.
Conclusion: The protocol described here yields abundant myocardial cells and provides a solid platform for further investigation of the pathogenesis, pharmacotherapy, and gene therapy of VSD with HF.
Keywords: Autophagy; Cardiomyocytes; Differentiation; Heart failure; Induced pluripotent stem cells; Small molecules; Urine-derived cells; Ventricular septal defect.
© 2018 The Author(s). Published by S. Karger AG, Basel.