Platelet-derived growth factor receptor-β-positive telocytes in skeletal muscle interstitium

Department of Cellular and Molecular Medicine, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania.
Journal of Cellular and Molecular Medicine (Impact Factor: 4.01). 12/2011; 16(4):701-7. DOI: 10.1111/j.1582-4934.2011.01505.x
Source: PubMed


Telocytes (TCs) represent a new cell type recently described in mammalian skeletal muscle interstitium as well as in other organs. These have a specific morphology and phenotype, both in situ and in vitro. Telocytes are cells with long and slender cell prolongations, in contact with other interstitial cells, nerve fibres, blood capillaries and resident stem cells in niches. Our aim was to investigate the potential contribution of TCs to micro-vascular networks by immunofluorescent labelling of specific angiogenic growth factors and receptors. We found that in human skeletal muscle TCs were constantly located around intermediate and small blood vessels and endomysial capillaries. Epi-fluorescence and laser confocal microscopy showed that TCs express c-kit, platelet-derived growth factor receptor (PDGFR)-β and VEGF, both in situ and in vitro. Telocytes were constantly located in the perivascular or pericapillary space, as confirmed by double staining of c-kit/CD31, PDGFR-β/CD31 and PDGFR-β/α-smooth muscle actin, respectively. Electron microscopy (EM) differentiated between pericytes and other cell types. Laminin labelling showed that TCs are not enclosed or surrounded by a basal lamina in contrast to mural cells. In conclusion, a) PDGFR-β could be used as a marker for TCs and b) TCs are presumably a transitional population in the complex process of mural cell recruitment during angiogenesis and vascular remodelling.

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Available from: Bogdan O Popescu, Sep 09, 2014
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    • "heart (Faussone-Pellegrini & Bani 2010, Gherghiceanu & Popescu 2010, 2012, Gherghiceanu et al. 2010, Kostin 2010, Mandache et al. 2010, Suciu et al. 2010a, Cismasiu et al. 2011, Manole et al. 2011, Rusu et al. 2012c), trachea (Zheng et al. 2011, Rusu et al. 2012a), lungs (Popescu et al. 2011a), blood vessels (Cantarero et al. 2011, Rusu et al. 2011), pancreas (Nicolescu & Popescu 2012), parotid gland (El-Bassouny 2012, Nicolescu et al. 2012), placenta (Suciu et al. 2010b), urinary tract (Gevaert et al. 2011, Koh et al. 2012), oesophagus (Rusu et al. 2012d), small intestine (Cantarero Carmona et al. 2011, Cretoiu et al. 2012b, 2012c) and endometrium (Hatta et al. 2012). TCs were also identified in: pleura (Hinescu et al. 2011), epicardium (Popescu et al. 2010), skeletal muscle (Bojin et al. 2011, Popescu et al. 2011b, Suciu et al. 2012), skin (Ceafalan et al. 2012, Rusu et al. 2012b) and neuromuscular spindles (Díaz-Flores et al. 2013). "
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    ABSTRACT: Telocytes (TCs) have been described in various organs and species ( as cells with telopodes (Tps) — very long cellular extensions with an alternation of thin segments (podomers) and dilated portions (podoms). We examined TCs using electron microscopy (EM), immunohistochemistry (IHC), immunofluorescence (IF), time-lapse videomicroscopy and whole-cell patch voltage-clamp. EM showed a three-dimensional network of dichotomous-branching Tps, a labyrinthine system with homo- and hetero-cellular junctions. Tps release extracellular vesicles (mean diameter of 160.6±6.9 nm in non-pregnant myometrium and 171.6±4.6 nm in pregnant myometrium), sending macromolecular signals to neighbouring cells. Comparative measurements (non-pregnant and pregnant myometrium) of podomer thickness revealed values of 81.94±1.77 nm vs. 75.53±1.81 nm, while the podoms diameters were 268.6±8.27 nm vs. 316.38±17.56 nm. IHC as well as IF revealed double c-kit and CD34 positive results. Time-lapse videomicroscopy of cell culture showed dynamic interactions between Tps and myocytes. In non-pregnant myometrium, patch-clamp recordings of TCs revealed a hyperpolarization-activated chloride inward current with calcium dependence and the absence of L-type calcium channels. TCs seems to have no excitable properties as the surrounding smooth muscle cells. In conclusion, this study shows the presence of TCs as a distinct cell type in human non-pregnant and pregnant myometrium and describes morphometric differences between the two physiological states. In addition, we provide a preliminary in vitro electrophysiological evaluation of the non-pregnant state suggesting that TCs could influence timing of the contractile activity of smooth muscle cells.
    Reproduction (Cambridge, England) 02/2013; 145(4):357-370. DOI:10.1530/REP-12-0369 · 3.17 Impact Factor
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    • "distinctive types of pericytes, or are TCs to be recruited as pericytes (Goritz et al., 2011, Suciu et al., 2012). Various research was performed before the TC definition in 2010 (Popescu and Faussone-Pellegrini, 2010), and several reports identified esophageal ICCs (Faussone-Pellegrini and Cortesini, 1985a, 1985b, 1986; Faussone-Pellegrini, 1987; Berezin et al., 1994; Burns et al., 1997; Rumessen et al., 2001; Zarate et al., 2006; Huizinga et al., 2008; Radenkovic et al., 2010), but not esophageal cells to be later considered TCs. "
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    ABSTRACT: Telocytes (TCs) are actually defined as being stromal cells with specific long and thin prolongations, called telopodes (Tp). They were positively identified in various tissues up to now. We report here for the first time the presence of TCs in the structure of esophagus. Such cells were identified under transmission electron microscopy (TEM) in esophageal samples of Wistar rats (N=5) and were found beneath the basal epithelial layer, in submucosa, closely related to smooth as well as striated muscular fibers, and also in adventitia. They were closely related to mast cells, macrophages, and microvessels. Hybrid morphologies of stromal cells processes were found: cytoplasmic processes continued distally in a telopodial fashion. Telopodes alone may not be enough for a safe diagnostic of TCs in TEM; a larger set of specific standards (such as the telopodial emergence, and the sizes of the cell body and telopodes) should be considered to differentiate TCs to various species of fibroblasts. The morphological and ultrastructural specific features should make the difference between TCs and interstitial cells of Cajal in the digestive tract.
    Cell Biology International 08/2012; 36(12). DOI:10.1042/CBI20120007 · 1.93 Impact Factor
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    ABSTRACT: Telocytes (TCs) form a cardiac network of interstitial cells. Our previous studies have shown that TCs are involved in heterocellular contacts with cardiomyocytes and cardiac stem/progenitor cells. In addition, TCs frequently establish 'stromal synapses' with several types of immunoreactive cells in various organs ( ). Using electron microscopy (EM) and electron microscope tomography (ET), we further investigated the interstitial cell network of TCs and found that TCs form 'atypical' junctions with virtually all types of cells in the human heart. EM and ET showed different junction types connecting TCs in a network (puncta adhaerentia minima, processus adhaerentes and manubria adhaerentia). The connections between TCs and cardiomyocytes are 'dot' junctions with nanocontacts or asymmetric junctions. Junctions between stem cells and TCs are either 'stromal synapses' or adhaerens junctions. An unexpected finding was that TCs have direct cell-cell (nano)contacts with Schwann cells, endothelial cells and pericytes. Therefore, ultrastructural analysis proved that the cardiac TC network could integrate the overall 'information' from vascular system (endothelial cells and pericytes), nervous system (Schwann cells), immune system (macrophages, mast cells), interstitium (fibroblasts, extracellular matrix), stem cells/progenitors and working cardiomyocytes. Generally, heterocellular contacts occur by means of minute junctions (point contacts, nanocontacts and planar contacts) and the mean intermembrane distance is within the macromolecular interaction range (10-30 nm). In conclusion, TCs make a network in the myocardial interstitium, which is involved in the long-distance intercellular signaling coordination. This integrated interstitial system appears to be composed of large homotropic zones (TC-TC junctions) and limited (distinct) heterotropic zones (heterocellular junctions of TCs).
    Cell and Tissue Research 02/2012; 348(2):265-79. DOI:10.1007/s00441-012-1333-8 · 3.57 Impact Factor
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