• Open Access

Epicardium: interstitial Cajal-like cells (ICLC) highlighted by immunofluorescence

Authors

  • L. Suciu,

    1. Department of Cellular and Molecular Medicine, ‘Carol Davila’ University of Medicine and Pharmacy, Bucharest, Romania
    2. ‘Victor Babes’ Institute of Pathology, Bucharest, Romania
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  • L. M. Popescu,

    Corresponding author
    1. Department of Cellular and Molecular Medicine, ‘Carol Davila’ University of Medicine and Pharmacy, Bucharest, Romania
    2. ‘Victor Babes’ Institute of Pathology, Bucharest, Romania
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  • T. Regalia,

    1. Department of Cellular and Molecular Medicine, ‘Carol Davila’ University of Medicine and Pharmacy, Bucharest, Romania
    2. ‘Victor Babes’ Institute of Pathology, Bucharest, Romania
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  • A. Ardelean,

    1. Cell Biology Laboratory, ‘Goldish University’, Arad, Romania
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  • C. G. Manole

    1. Department of Cellular and Molecular Medicine, ‘Carol Davila’ University of Medicine and Pharmacy, Bucharest, Romania
    2. ‘Victor Babes’ Institute of Pathology, Bucharest, Romania
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*Correspondence to: L.M. POPESCU, M.D., Ph.D., Department of Cellular and Molecular Medicine, ‘Carol Davila’ University of Medicine and Pharmacy, P.O. Box 35–29, Bucharest 35, Romania. E-mail: lmp@jcmm.org

Abstract

During the last few years, there is an increasing interest in the role of the epicardium in cardiac development, myocardial remodelling or repair and regeneration. Several types of cells were described in the subepicardial loose connective tissue, beneath the epicardial mesothe-lium. We showed previously (repeatedly) the existence of interstitial Cajal-like cells (ICLCs) in human and mammalian myocardium, either in atria or in ventricles. Here, we describe ICLCs in adult mice epicardium and primary culture as well as in situ using frozen sections. The identification of ICLCs was based on phase contrast microscopy and immunophenotyping. We found cells with characteristic morphologic aspects: spindle-shaped, triangular or polygonal cell body and typical very long (tens to hundreds micrometres) and very thin cyto-plasmic processes, with a distinctive ‘beads-on-a-string’ appearance. The dilations contain mitochondria, as demonstrated by MitoTracker Green FM labelling of living cells. Epicardial ICLCs were found positive for c-kit/CD117 and/or CD34. However, we also observed ICLCs positive for c-kit and vimentin. In conclusion, ICLCs represent a distinct cell type in the subendocardium, presumably comprising at least two subpopulations: (i) c-kit/CD34-positive and (ii) only c-kit-positive. ICLCs might be essential as progenitor (or promoter) cells for developing cardiomyocyte lineages in normal and/or injured heart.

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