Telocytes and stem cells in limbus and uvea of mouse eye

Authors

  • María José Luesma,

    1. Department of Human Anatomy and Histology, Faculty of Medicine, University of Zaragoza, Zaragoza, Spain
    2. Aragon Health Research Institute (IIS Aragón), Zaragoza, Spain
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    • These authors contributed equally to this study.
  • Mihaela Gherghiceanu,

    1. Laboratory of Electron Microscopy, ‘Victor Babeş’ National Institute of Pathology, Bucharest, Romania
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    • These authors contributed equally to this study.
  • Laurenţiu M. Popescu

    Corresponding author
    1. Department of Cellular and Molecular Medicine, ‘Carol Davila’ University of Medicine, Bucharest, Romania
    2. Division of Advanced Studies, ‘Victor Babeş’ National Institute of Pathology, Bucharest, Romania
    • Department of Human Anatomy and Histology, Faculty of Medicine, University of Zaragoza, Zaragoza, Spain
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Correspondence to: Prof. Laurenţiu M. POPESCU, Division of Advanced Studies, ‘Victor Babeş’ National Institute of Pathology, Bucharest, Romania.

Tel.: +40213194530

Fax: +40213194528

E-mail: lpopescu@jcmm.org

Abstract

The potential of stem cell (SC) therapies for eye diseases is well-recognized. However, the results remain only encouraging as little is known about the mechanisms responsible for eye renewal, regeneration and/or repair. Therefore, it is critical to gain knowledge about the specific tissue environment (niches) where the stem/progenitor cells reside in eye. A new type of interstitial cell–telocyte (TC) (www.telocytes.com) was recently identified by electron microscopy (EM). TCs have very long (tens of micrometres) and thin (below 200 nm) prolongations named telopodes (Tp) that form heterocellular networks in which SCs are embedded. We found TCs by EM and electron tomography in sclera, limbus and uvea of the mouse eye. Furthermore, EM showed that SCs were present in the anterior layer of the iris and limbus. Adhaerens and gap junctions were found to connect TCs within a network in uvea and sclera. Nanocontacts (electron-dense structures) were observed between TCs and other cells: SCs, melanocytes, nerve endings and macrophages. These intercellular ‘feet’ bridged the intercellular clefts (about 10 nm wide). Moreover, exosomes (extracellular vesicles with a diameter up to 100 nm) were delivered by TCs to other cells of the iris stroma. The ultrastructural nanocontacts of TCs with SCs and the TCs paracrine influence via exosomes in the epithelial and stromal SC niches suggest an important participation of TCs in eye regeneration.

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