Recently discovered interstitial cells termed telocytes: distinguishing cell-biological and histological facts from fictions

Varga, Ivan; Kyselovič, Ján; Danišovič, Ľuboš; Gálfiová, Paulína; Kachlík, David; Polák, Štefan; Klein, Martin

doi:10.2478/s11756-018-0162-y

Cited by 20 publications

(17 citation statements)

References 66 publications

(65 reference statements)

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“…Both appear as large and degranulating cells. All these observations support recent and consistent evidence for TCs' failure to be categorized as a distinctive cell type [11,24,26].…”

Section: What Are (Sub)epicardial Tcs?supporting

confidence: 88%

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The Telocytes in the Subepicardial Niche

et al. 2019

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A great interest has developed over the last several years in research on interstitial Cajal-like cells (ICLCs), later renamed to telocytes (TCs). Such studies are restricted by diverse limitations. We aimed to critically review (sub)epicardial ICLCs/TCs and to bring forward supplemental immunohistochemical evidence on (sub)epicardial stromal niche inhabitants. We tested the epicardial expressions of CD117/c-kit, CD34, Cytokeratin 7 (CK7), Ki67, Platelet-Derived Growth Factor Receptor (PDGFR)-α and D2-40 in adult human cardiac samples. The mesothelial epicardial cells expressed D2-40, CK7, CD117/c-kit and PDGFR-α. Subepicardial D2-40-positive lymphatic vessels and isolated D2-40-positive and CK7-positive subepicardial cells were also found. Immediate submesothelial spindle-shaped cells expressed Ki-67. Submesothelial stromal cells and endothelial tubes were PDGFR-α-positive and CD34-positive. The expression of CD34 was pan-stromal, so a particular stromal cell type could not be distinguished. The stromal expression of CD117/c-kit was also noted. It seems that epicardial TCs could not be regarded as belonging to a unique cell type until (pre)lymphatic endothelial cells are inadequately excluded. Markers such as CD117/c-kit or CD34 seem to be improper for identifying TCs as a distinctive cell type. Care should be taken when using the immunohistochemical method and histological interpretations, as they may not produce accurate results.

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“…Both appear as large and degranulating cells. All these observations support recent and consistent evidence for TCs' failure to be categorized as a distinctive cell type [11,24,26].…”

Section: What Are (Sub)epicardial Tcs?supporting

confidence: 88%

“…Nevertheless, TCs, as a group, could simply be the result of a lack of uniformity and consensus in the terminology relating to CD34-positive stromal cells used by different research teams [23]. Telocytes do not appear in the Terminologia Histologica [24,25].…”

Section: Introductionmentioning

confidence: 99%

The Telocytes in the Subepicardial Niche

et al. 2019

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“…Some studies claim that some of the CD34+ TCs can also be positive for α-SMA+, serving as the source cells for differentiation into fibroblasts and myofibroblasts. These dual immunophenotype TCs serve in the repair of damaged sites through formation of granulation tissue and fibrosis [67]. There has been a wide debate on TC-specific antigens.…”

Section: Discussionmentioning

confidence: 99%

Identification of Telocytes in the Pancreas of Turtles—A role in Cellular Communication

Gandahi

Ding

Shi

et al. 2020

IJMS

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The existence of telocytes (TCs) has not yet been established in the pancreases of aquatic reptiles. Here, we report TCs in the exocrine pancreas of Pelodiscus sinensis using transmission electron microscope (TEM), immunohistochemistry (IHC), and immunofluorescence (IF) techniques. TCs surrounded the acini and ducts of the connective tissue of the exocrine pancreas and between lobules and gland cells. The cells were located preferably close to the blood vessels, interlobular ducts, and nerve fibers. Ultrastructurally, TCs exhibited small and large bodies with thick and thin portions, podoms, and podomers, and prolongations that form dichotomous branching with hetero-cellular and homo-cellular junctions. The podom (thick) portions showed caveolae, mitochondria, rough endoplasmic reticulum, and vesicles. The nucleus carries heterochromatin and is irregular in shape. The shape of TCs depends on the number of telopodes (Tps) bearing long, short, spindle, triangular, and “beads on a string” shapes with twisted, tortuous prolongations and ramifications. Shed extracellular vesicles and exosomes were found frequently released from projections and Tps within connective tissue in the vicinity of the acini and collagen fibers. IHC and IF results showed CD34+, α-SMA+, and vimentin+, long and triangle-shaped TCs, consistent with the TEM findings. The presence of shaded vesicles from TCs might implicate their possible role in immune surveillance, tissue regeneration as well as regulatory functions in the reptilian pancreas.

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“…However, telocytes are not noted for large intracellular inclusions, phagocytic/endocytic properties, or expression of lymphatic-associated markers as seen in LLECs [8,16]. In addition, the processes of LLECs are not as long and fine as in telocytes, which can be hundreds of µm long [15] and as thin as 0.2 μm [65]. LLECs and telocytes are therefore likely to be distinct classes of cells.…”

Section: Telocytesmentioning

confidence: 97%

Structural and functional conservation of non-lumenized lymphatic endothelial cells in the mammalian leptomeninges

et al. 2019

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The vertebrate CNS is surrounded by the meninges, a protective barrier comprised of the outer dura mater and the inner leptomeninges, which includes the arachnoid and pial layers. While the dura mater contains lymphatic vessels, no conventional lymphatics have been found within the brain or leptomeninges. However, non-lumenized cells called Brain/Mural Lymphatic Endothelial Cells or Fluorescent Granule Perithelial cells (muLECs/BLECs/FGPs) that share a developmental program and gene expression with peripheral lymphatic vessels have been described in the meninges of zebrafish. Here we identify a structurally and functionally similar cell type in the mammalian leptomeninges that we name Leptomeningeal Lymphatic Endothelial Cells (LLEC). As in zebrafish, LLECs express multiple lymphatic markers, containing very large, spherical inclusions, and develop independently from the meningeal macrophage lineage. Mouse LLECs also internalize macromolecules from the cerebrospinal fluid, including Amyloid-β, the toxic driver of Alzheimer's disease progression. Finally, we identify morphologically similar cells co-expressing LLEC markers in human post-mortem leptomeninges. Given that LLECs share molecular, morphological, and functional characteristics with both lymphatics and macrophages, we propose they represent a novel, evolutionary conserved cell type with potential roles in homeostasis and immune organization of the meninges.

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Recently discovered interstitial cells termed telocytes: distinguishing cell-biological and histological facts from fictions

Cited by 20 publications

References 66 publications

The Telocytes in the Subepicardial Niche

The Telocytes in the Subepicardial Niche

Identification of Telocytes in the Pancreas of Turtles—A role in Cellular Communication

Structural and functional conservation of non-lumenized lymphatic endothelial cells in the mammalian leptomeninges

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