Feinberg, Adam W.Ripplinger, Crystal M.van der Meer, PeterSheehy, Sean P.Domian, IbrahimChien, Kenneth R.Parker, Kevin Kit2014-03-112013Feinberg, Adam W., Crystal M. Ripplinger, Peter van der Meer, Sean P. Sheehy, Ibrahim Domian, Kenneth R. Chien, and Kevin Kit Parker. 2013. “Functional Differences in Engineered Myocardium from Embryonic Stem Cell-Derived versus Neonatal Cardiomyocytes.” Stem Cell Reports 1 (5): 387-396. doi:10.1016/j.stemcr.2013.10.004. http://dx.doi.org/10.1016/j.stemcr.2013.10.004.2213-6711http://nrs.harvard.edu/urn-3:HUL.InstRepos:11879140Summary Stem cell-derived cardiomyocytes represent unique tools for cell- and tissue-based regenerative therapies, drug discovery and safety, and studies of fundamental heart-failure mechanisms. However, the degree to which stem cell-derived cardiomyocytes compare to mature cardiomyocytes is often debated. We reasoned that physiological metrics of engineered cardiac tissues offer a means of comparison. We built laminar myocardium engineered from cardiomyocytes that were differentiated from mouse embryonic stem cell-derived cardiac progenitors or harvested directly from neonatal mouse ventricles, and compared their anatomy and physiology in vitro. Tissues assembled from progenitor-derived myocytes and neonate myocytes demonstrated similar cytoskeletal architectures but different gap junction organization and electromechanical properties. Progenitor-derived myocardium had significantly less contractile stress and slower longitudinal conduction velocity than neonate-derived myocardium, indicating that the developmental state of the cardiomyocytes affects the electromechanical function of the resultant engineered tissue. These data suggest a need to establish performance metrics for future stem cell applications.en-USJournal Article2014-03-1110.1016/j.stemcr.2013.10.004