Two-photon microscopy of healthy, infarcted and stem-cell treated regenerating heart

Authors

  • Marika A. Wallenburg,

    1. Ontario Cancer Institute, Division of Biophysics and Bioimaging, University Health Network and University of Toronto, Department of Medical Biophysics, 610 University Avenue, Toronto, ON, M5G 2M9, CANADA
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  • Jun Wu,

    1. Toronto General Research Institute, Division of Cardiovascular Surgery, University Health Network and University of Toronto, Toronto, Ontario, Canada, 610 University Avenue, Toronto, ON, M5G 2M9, CANADA
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  • Ren-Ke Li,

    1. Toronto General Research Institute, Division of Cardiovascular Surgery, University Health Network and University of Toronto, Toronto, Ontario, Canada, 610 University Avenue, Toronto, ON, M5G 2M9, CANADA
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  • I. Alex Vitkin

    Corresponding author
    1. Ontario Cancer Institute, Division of Biophysics and Bioimaging, University Health Network and University of Toronto, Departments of Medical Biophysics and Radiation Oncology, 610 University Avenue, Toronto, ON, M5G 2M9, CANADA
    • Phone: (416) 946-2990, Fax: (416) 946-6566
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Abstract

Two-photon excitation autofluorescence (produced in myocytes) and second-harmonic generation (produced mainly by collagen) allow label-free visualization of these two important components of myocardium. Because of their different emission wavelengths, these two signals can be separated spectrally. Here, we examine two-photon microscopy images of healthy, infarcted and stem-cell treated rat hearts. We find that in infarcted heart, regions distant from the site of infarct are similar to healthy tissue in composition (mostly myocytes, very little collagen) and organization (densely packed myocytes), but infarct regions are characterized by sparse myocytes and high collagen content indicative of scar tissue formation. Stem cell treated hearts, in contrast, show regions of intertwined myocytes and collagen throughout the infarct, suggesting reduced tissue damage. Finally, these results offer interesting insights into our ongoing polarized light studies of cardiac tissue anisotropy, and reveal that both tissue composition and tissue micro-organization are reflected in polarization-measured linear retardance values. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

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