• Open Access

Identification of telocytes in skeletal muscle interstitium: implication for muscle regeneration

Authors

  • L. M. Popescu,

    Corresponding author
    1. Department of Cellular and Molecular Medicine, ‘Carol Davila’ University of Medicine and Pharmacy, Bucharest, Romania
    2. ‘Victor Babeş’ National Institute of Pathology, Bucharest, Romania
      Correspondence to: L. M. POPESCU, MD, PhD, 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
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  • Emilia Manole,

    1. ‘Victor Babeş’ National Institute of Pathology, Bucharest, Romania
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  • Crenguţa S. Şerboiu,

    1. Department of Cellular and Molecular Medicine, ‘Carol Davila’ University of Medicine and Pharmacy, Bucharest, 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 Babeş’ National Institute of Pathology, Bucharest, Romania
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  • Laura C. Suciu,

    1. Department of Cellular and Molecular Medicine, ‘Carol Davila’ University of Medicine and Pharmacy, Bucharest, Romania
    2. ‘Victor Babeş’ National Institute of Pathology, Bucharest, Romania
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  • Mihaela Gherghiceanu,

    1. ‘Victor Babeş’ National Institute of Pathology, Bucharest, Romania
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  • B. O. Popescu

    1. ‘Victor Babeş’ National Institute of Pathology, Bucharest, Romania
    2. Department of Neurology, University Hospital, ‘Carol Davila’ University of Medicine and Pharmacy, Bucharest, Romania
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Correspondence to: L. M. POPESCU, MD, PhD, 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

Skeletal muscle interstitium is crucial for regulation of blood flow, passage of substances from capillaries to myocytes and muscle regeneration. We show here, probably, for the first time, the presence of telocytes (TCs), a peculiar type of interstitial (stromal) cells, in rat, mouse and human skeletal muscle. TC features include (as already described in other tissues) a small cell body and very long and thin cell prolongations—telopodes (Tps) with moniliform appearance, dichotomous branching and 3D-network distribution. Transmission electron microscopy (TEM) revealed close vicinity of Tps with nerve endings, capillaries, satellite cells and myocytes, suggesting a TC role in intercellular signalling (via shed vesicles or exosomes). In situ immunolabelling showed that skeletal muscle TCs express c-kit, caveolin-1 and secrete VEGF. The same phenotypic profile was demonstrated in cell cultures. These markers and TEM data differentiate TCs from both satellite cells (e.g. TCs are Pax7 negative) and fibroblasts (which are c-kit negative). We also described non-satellite (resident) progenitor cell niche. In culture, TCs (but not satellite cells) emerge from muscle explants and form networks suggesting a key role in muscle regeneration and repair, at least after trauma.

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