Molecular characterization and functional properties of cardiomyocytes derived from human inducible pluripotent stem cells

Abstract

In view of the therapeutic potential of cardiomyocytes derived from induced pluripotent stem (iPS) cells (iPS-derived cardiomyocytes), in the present study we investigated in iPS-derived cardiomyocytes, the functional properties related to [Ca2+]i handling and contraction, the contribution of the sarcoplasmic reticulum (SR) Ca2+ release to contraction and the b-adrenergic inotropic responsiveness. The two iPS clones investigated here were generated through infection of human foreskin fibroblasts (HFF) with retroviruses containing the four human genes: OCT4, Sox2, Klf4 and C-Myc. Our major findings showed that iPS-derived cardiomyocytes: (i) express cardiac specific RNA and proteins; (ii) exhibit negative force–frequency relations and mild (compared to adult) post-rest potentiation; (iii) respond to ryanodine and caffeine, albeit less than adult cardiomyocytes, and express the SR-Ca2+ handling proteins ryanodine receptor and calsequestrin. Hence, this study demonstrates that in our cardiomyocytes clones differentiated from HFF-derived iPS, the functional properties related to excitation–contraction coupling, resemble in part those of adult cardiomyocytes.

Screening of human pluripotent stem cells using CGH and FISH reveals low-grade mosaic aneuploidy and a recurrent amplification of chromosome 1q

“…The cells were cultured with inactivated MEF as previously described. 20 HESCs and hiPSCs were passaged every 4-6 days using 1.5 mg/ml type IV collagenase (Worthington Biochemical Corporation, Lakewood, NJ, USA). We used previously defined criteria for characterization of hES and hiPS cells by examining their morphology, surface markers, growth rates, karyotype and pluripotency.…”

We heart cultured hearts. A comparative review of methodologies for targeted differentiation and maintenance of cardiomyocytes derived from pluripotent and multipotent stem cells

“…Cardiomyocytes derived by targeted differentiation from iPSC also exhibit the basic properties of cardiac muscle cells, namely: propensity for spontaneous rhythmic pulsation; expression of cardio-specific RNA and proteins and capacity for response to caffeine and ryanodine [71]. However, the same authors have reported that cardiomyocytes derived from iPSC exhibited negative force-frequency relationship and lower postrest potentiation than adult cardiac cells [71].…”

“…Diminished post-rest potentiation of the cardiac muscle is commonly seen in various cardiovascular conditions, including progressive heart hypertrophy and dilated cardiomyopathy; as well as in normal ageing. The responses to caffeine and ryanodine of iPSC-derived cardiomyocytes were also weaker than the response of adult cardiomyocytes [71]. Caffeine normally triggers an increase in cytosolic Ca 2+ whereas ryanodine decreases the levels of Ca 2+ , therefore, the maintenance of the balance of Ca 2+ levels in cardiomyocytes derived from pluripotent stem cells may not be identical to the balance in normal adult cardiomyocytes.…”

“…However, the same authors have reported that cardiomyocytes derived from iPSC exhibited negative force-frequency relationship and lower postrest potentiation than adult cardiac cells [71]. The force-frequency relationship is termed 'positive' when contractility increases as stimulation frequencies are stepped up and 'negative' when increased frequency of stimulation is associated with reduced contraction force [72,73].…”

“…Two years later, cardiomyocytelike cells were derived from human foreskin fibroblasts preprogrammed to pluripotency by infection with retroviral vectors carrying the human pluripotency genes OCT4, SOX2, KLF4 and C-MYC (the 4-gene protocol) [71].…”