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: 4.75). 12/2011; 16(4):701-7. DOI: 10.1111/j.1582-4934.2011.01505.x
Source: PubMed

ABSTRACT 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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    ABSTRACT: Telocytes (TCs) are a novel type of interstitial cell of whom presence has been recently documented in many tissues and organs. However, whether TCs exists in bone marrow is still not reported. This study aims to find out TCs in mice bone marrow by using scanning electron microscope (SEM) and transmission electron microscope (TEM). SEM images showed that in mice bone marrow most of TCs have small spherical cell body (usually 4–6 μm diameter) with thin long telopodes (Tps; usually one to three). The longest Tp observed was about 70 μm, with an uneven calibre. Direct intercellular contacts exist between TCs. TEM shows mitochondria within dilations of Tps. Also, by TEM, we show the close spatial relations of Tps with blood vessels. In conclusion, this study provides ultrastructural evidence regarding the existence of TCs in mice bone marrow, in situ.
    Journal of Cellular and Molecular Medicine 06/2014; 18(6). · 4.75 Impact Factor
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    ABSTRACT: Valve interstitial cells (VICs) are responsible for maintaining the structural integrity and dynamic behaviour of the valve. Telocytes (TCs), a peculiar type of interstitial cells, have been recently identified by Popescu's group in epicardium, myocardium and endocardium (visit The presence of TCs has been identified in atria, ventricles and many other tissues and organ, but not yet in heart valves. We used transmission electron microscopy and immunofluorescence methods (double labelling for CD34 and c-kit, or vimentin, or PDGF Receptor-β) to provide evidence for the existence of TCs in human heart valves, including mitral valve, tricuspid valve and aortic valve. TCs are found in both apex and base of heart valves, with a similar density of 27–28 cells/mm2 in mitral valve, tricuspid valve and aortic valve. Since TCs are known for the participation in regeneration or repair biological processes, it remains to be determined how TCs contributes to the valve attempts to re-establish normal structure and function following injury, especially a complex junction was found between TCs and a putative stem (progenitor) cell.
    Journal of Cellular and Molecular Medicine 03/2014; · 4.75 Impact Factor
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    ABSTRACT: Telocytes (TCs) are a unique type of interstitial cells with specific, extremely long prolongations named telopodes (Tps). Our previous study showed that TCs are distinct from fibroblasts (Fbs) and mesenchymal stem cells (MSCs) as concerns gene expression and proteomics. The present study explores patterns of mouse TC-specific gene profiles on chromosome 1. We investigated the network of main genes and the potential functional correlations. We compared gene expression profiles of mouse pulmonary TCs, MSCs, Fbs, alveolar type II cells (ATII), airway basal cells (ABCs), proximal airway cells (PACs), CD8+ T cells from bronchial lymph nodes (T-BL) and CD8+ T cells from lungs (T-LL). The functional and feature networks were identified and compared by bioinformatics tools. Our data showed that on TC chromosome 1, there are about 25% up-regulated and 70% down-regulated genes (more than onefold) as compared with the other cells respectively. Capn2, Fhl2 and Qsox1 were over-expressed in TCs compared to the other cells, indicating that biological functions of TCs are mainly associated with morphogenesis and local tissue homoeostasis. TCs seem to have important roles in the prevention of tissue inflammation and fibrogenesis development in lung inflammatory diseases and as modulators of immune cell response. In conclusion, TCs are distinct from the other cell types.
    Journal of Cellular and Molecular Medicine 05/2014; 18(5). · 4.75 Impact Factor

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