Introduction:
Human somatic cells can be reprogrammed into primitive stem cells, termed induced pluripotent stem cells (iPSCs). These iPSCs can be extensively expanded in vitro and differentiated into multiple functional cell types, enabling faithful preservation of individual’s genotype and large scale production of disease targeted cellular components. These unique cellular reagents thus hold tremendous potential in disease mechanism study, drugs screening and cell replacement therapy. Due to the genetic mutation of the protein dystrophin, many DMD patients develop fatal cardiomyopathy with no effective treatment. The underlying pathogenesis has not been fully elucidated.
Hypothesis:
We tested the hypothesis that iPSCs could be generated from DMD patients’ urine samples and differentiated into cardiomyocytes, recapitulating the dystrophic phenotype.
Methods:
iPSCs generation was achieved by introducing a lentiviral vector expressing Oct4, Sox2, c-Myc and Klf4 into cells derived from patient’s (n=1) and healthy volunteers’ (n=3) urine. Cardiomyocytes were derived by sequentially treating iPSCs with GSK3 inhibitor CHIR99021 and Wnt inhibitor IWP4. Differentiated cardiomyocytes were subjected to calcium imaging, electrophysiology recording, Polymerase Chain Reaction (PCR) analysis, and immunostaining.
Results:
iPSCs were efficiently generated from human urine samples and further forced to differentiate into contracting cardiomyocytes. PCR analysis and immunostaining confirmed the expression of a panel of cardiac markers. Both normal and patient iPSC derived cardiomyocytes exhibited spontaneous and field stimulated calcium transients (up to 2Hz), as well as action potentials with ventricular-like and nodal-like characteristics. Anti-dystrophin antibodies stained normal iPSC-derived cardiomyocyte membranes but did not react against DMD iPSC-derived cardiomyocytes.
Conclusions:
Cardiomyocytes can be efficiently generated from human urine, through the cellular reprogramming technology. DMD cardiomyocytes retained the patient’s genetic information and manifested a dystrophin-null phenotype. Functional assessments are underway to determine differences that may exist between genotypes.
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