Abstract 3227: Molecular Characterization of Induced Pluripotent Stem (iPS) Cell-Derived Cardiomyocytes
[Background] We recently reported that mouse and human iPS cells could be generated from somatic cells by gene transfer of Oct3/4, Sox2, c-Myc and Klf4. Although the morphology, growth characteristics and pluripotency of iPS cells are believed to be similar to those of ES cells, there are several versions such as Fbx-iPS, Nanog-iPS cells, and it remains unknown whether which type of iPS cell could be appropriate for heart regenerative therapy. This study investigated the cardiomyocyte differentiation potential of mouse iPS cells and molecular characterization of iPS-induced cardiomyocytes.
[Methods and Results]
We used several lines of Fbx-iPS and Nanog-iPS cells and induced cardiomyocyte differentiation using the hanging drop culture method. Mouse ES cells were used as control. Both Fbx-iPS and Nanog-iPS cells could differentiate into cardiomyocytes, however, the beating incidence of Nanog-iPS derived embryoid bodies was higher than that of Fbx-iPS derived embryoid bodies.
RT-PCR analyses and immunohistochemistry revealed that both iPS cells expressed typical cardiomyocyte marker genes including Nkx2.5, GATA4, MEF2C, myosin light chain-2v, α-myosin heavy chain, atrial natriuretic peptide, and α-sarcomeric actinin, and they showed normal structures.
Electrical physiological study showed that iPS cell derived cardiomyocytes had sinus node-like, atrial-like or fetal ventricular type action potentials.
iPS cell derived cardiomyocytes were purified and analyzed for exogenous transgene expression which revealed that Fbx-iPS cells remained higher expression level of exogenous transgene compared with Nanog-iPS.
Higher expression level of exogenous trangene may have contributed to lower incidence of beating colonies, preventing differentiation to cardiomyocyte.
[Conclusions] Nanog-iPS cells seem to be more feasible than Fbx-iPS cells as source of regeneration therapy in terms of higher cardiomyocyte differentiation potential and lower expression level of exogenous transgene. The iPS cells proved to be an attractive cell source for the regeneration of cardiomyocytes, however safety and careful characterization is necessary before clinical application.