Cardiovascular research and regenerative strategies have been significantly limited by the lack of relevant human cell types. Human embryonic stem cells (hESCs) differentiated into cardiomyocytes have potential to address these shortcomings but ethical concerns have hampered their widespread use. The recent breakthrough in somatic cell reprogramming to generate induced pluripotent stem (iPS) cells offers new opportunities to use patient specific cells for regeneration, research and pharmacological testing. Like cardiomyocytes generated from hESCs, iPS cell derived cardiomyocytes (iPS-CMs) express many morphological and functional markers of adult cardiomyocytes, however, they remain embryonic in phenotype due to incomplete differentiation and residual epigenetic memory. Not surprisingly, the most significant challenge in the use of iPS-CMs has been generating phenotypically mature cardiomyocytes in culture. The heart is a highly adaptive organ and during development, coordinated delivery of mechanical stresses like pressure, flow and stretch direct transformation of a monolayer of cells into a complex 4-chambered organ. While iPS-CMs have been genetically reprogrammed and differentiated, they are cultured in static culture environments. We hypothesize that complete transformation of iPS-CMs into functional adult cardiomyocytes requires differentiation and maturation in an environment where mechanical stresses can be gradually increased from embryonic levels to adult levels followed by imposition of 'work'. To accomplish this we will use our cardiac cell culture model (CCCM) which was developed as a left-ventricle mimic to enable culture of cardiac cells in a physiologically relevan environment. This model represents the state-of-the-art in cardiac cell culture and is the only model currently available that can accurately mimic mechanical stresses associated with embryonic levels to adult levels with the ability to impose 'work' on cultured cells. In this proposal we seek to establish an appropriate conditioning regime to phenotypically mature iPS-CMs that are still embryonic in phenotype and transform them into adult cardiomyocytes via appropriate mechanical conditioning and work imposition. iPS-CMs differentiated and matured within the CCCM will be extensively evaluated and characterized to quantify morphological and functional differences in comparison to both unstimulated iPS-CMs and published data from adult myocytes. Adult iPS-CMs generated via mechanical conditioning and work imposition has great potential for cardiovascular research, cardiac tissue regeneration without the risk of immune rejection, and patient specific drug testing and therapeutics.
iPS-CMs have shown great potential as a patient specific source of cardiomyocytes for cardiac tissue generation and drug testing. This project will focus on transformation of iPS-CMs from an embryonic cardiomyocyte phenotype into an adult phenotype via gradual mechanical conditioning and imposition of work to mimic the in vivo cardiac environment.
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