Bio

Professional Education


  • Doctor of Philosophy, Univ of Texas Southwestern Medical Center (2008)

Stanford Advisors


Teaching

Graduate and Fellowship Programs


  • Pediatric Cardiology (Fellowship Program)

Publications

All Publications


  • Time-dependent evolution of functional vs. remodeling signaling in induced pluripotent stem cell-derived cardiomyocytes and induced maturation with biomechanical stimulation FASEB JOURNAL Jung, G., Fajardo, G., Ribeiro, A. J., Kooiker, K. B., Coronado, M., Zhao, M., Hu, D., Reddy, S., Kodo, K., Sriram, K., Insel, P. A., Wu, J. C., Pruitt, B. L., Bernstein, D. 2016; 30 (4): 1464-1479

    Abstract

    Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are a powerful platform for uncovering disease mechanisms and assessing drugs for efficacy/toxicity. However, the accuracy with which hiPSC-CMs recapitulate the contractile and remodeling signaling of adult cardiomyocytes is not fully known. We used β-adrenergic receptor (β-AR) signaling as a prototype to determine the evolution of signaling component expression and function during hiPSC-CM maturation. In "early" hiPSC-CMs (less than or equal to d 30), β2-ARs are a primary source of cAMP/PKA signaling. With longer culture, β1-AR signaling increases: from 0% of cAMP generation at d 30 to 56.8 ± 6.6% by d 60. PKA signaling shows a similar increase: 15.7 ± 5.2% (d 30), 49.8 ± 0.5% (d 60), and 71.0 ± 6.1% (d 90). cAMP generation increases 9-fold from d 30 to 60, with enhanced coupling to remodeling pathways (e.g., Akt and Ca(2+)/calmodulin-dependent protein kinase type II) and development of caveolin-mediated signaling compartmentalization. By contrast, cardiotoxicity induced by chronic β-AR stimulation, a major component of heart failure, develops much later: 5% cell death at d 30 vs. 55% at d 90. Moreover, β-AR maturation can be accelerated by biomechanical stimulation. The differential maturation of β-AR functional vs. remodeling signaling in hiPSC-CMs has important implications for their use in disease modeling and drug testing. We propose that assessment of signaling be added to the indices of phenotypic maturation of hiPSC-CMs.-Jung, G., Fajardo, G., Ribeiro, A. J. S., Kooiker, K. B., Coronado, M., Zhao, M., Hu, D.-Q., Reddy, S., Kodo, K., Sriram, K., Insel, P. A., Wu, J. C., Pruitt, B. L., Bernstein, D. Time-dependent evolution of functional vs. remodeling signaling in induced pluripotent stem cell-derived cardiomyocytes and induced maturation with biomechanical stimulation.

    View details for DOI 10.1096/fj.15-280982

    View details for Web of Science ID 000372629100009

  • hiPSC Modeling of Inherited Cardiomyopathies. Current treatment options in cardiovascular medicine Jung, G., Bernstein, D. 2014; 16 (7): 320-?

    Abstract

    Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) represent a powerful new model system to study the basic mechanisms of inherited cardiomyopathies. hiPSC-CMs have been utilized to model several cardiovascular diseases, achieving the most success in the inherited arrhythmias, including long QT and Timothy syndromes (Moretti et al. N Engl J Med. 363:1397-409, 2010; Yazawa et al. Nature. 471:230-4, 2011) and arrhythmogenic right ventricular dysplasia (ARVD) (Ma et al. Eur Heart J. 34:1122-33, 2013). Recently, studies have applied hiPSC-CMs to the study of both dilated (DCM) (Sun et al. Sci Transl Med. 4:130ra47, 2012) and hypertrophic (HCM) cardiomyopathies (Lan et al. Cell Stem Cell. 12:101-13, 2013; Carvajal-Vergara et al. Nature. 465:808-12, 2010), providing new insights into basic mechanisms of disease. However, hiPSC-CMs do not recapitulate many of the structural and functional aspects of mature human cardiomyocytes, instead mirroring an immature - embryonic or fetal - phenotype. Much work remains in order to better understand these differences, as well as to develop methods to induce hiPSC-CMs into a fully mature phenotype. Despite these limitations, hiPSC-CMs represent the best current in vitro correlate of the human heart and an invaluable tool in the search for mechanisms underlying cardiomyopathy and for screening new pharmacologic therapies.

    View details for DOI 10.1007/s11936-014-0320-7

    View details for PubMedID 24838688