Ultrastructural and immunohistochemical characteristics of telocytes in the skin and skeletal muscle of newborn rats

Arafat, Eetmad A.

doi:10.1016/j.acthis.2016.06.001

Cited by 13 publications

(15 citation statements)

References 57 publications

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“…In the present study we have described for the first time the distribution of TCs in murine skeletal muscles damaged by forced EC and provided novel experimental evidence supporting their morpho-functional interaction with activated SCs. In particular, confocal immunofluorescence analysis of intact control muscle sections revealed the presence of CD34 + CD31 − elongated, thin and varicose processes organized in an interstitial network alongside the striated myofibers and around blood vessels, consistent with the previous description of telopodes of TCs in the endomysial and perimysial sheaths of skeletal muscle 10,13–15,17 . Notably, in EC-damaged muscles this CD34 + CD31 − telopode network appeared particularly extended and was preferentially arranged around activated SCs that displayed Pax7 and MyoD nuclear positivity and were located in their distinctive site at the periphery of striated myofibers.…”

Section: Discussionsupporting

confidence: 88%

“…Only recently, TCs entered this scenario as a new distinctive type of interstitial cells that may potentially behave as nursing cells for SC-mediated skeletal muscle regeneration. However, it must be frankly recognized that such supporting role for TCs has only been supposed on the basis of their in situ identification in the close vicinity of SCs in healthy skeletal muscles 10,13–15,17 , their possible role during early myogenesis 28 , and their well-documented interaction and/or cross-talk with stem/progenitor cells in other organs 3,10,29–34 . Indeed, at present, the effective occurrence of a morpho-functional interplay between TCs and SCs in injured skeletal muscles has yet to be demonstrated with certainty.…”

Section: Discussionmentioning

confidence: 99%

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Morphological evidence for telocytes as stromal cells supporting satellite cell activation in eccentric contraction-induced skeletal muscle injury

Manetti

Tani

Rosa

et al. 2019

Sci Rep

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Although telocytes (TCs) have been proposed to play a “nursing” role in resident satellite cell (SC)-mediated skeletal muscle regeneration, currently there is no evidence of TC-SC morpho-functional interaction following tissue injury. Hence, we explored the presence of TCs and their relationship with SCs in an ex vivo model of eccentric contraction (EC)-induced muscle damage. EC-injured muscles showed structural/ultrastructural alterations and changes in electrophysiological sarcolemnic properties. TCs were identified in control and EC-injured muscles by either confocal immunofluorescence (i.e. CD34+CD31− TCs) or transmission electron microscopy (TEM). In EC-injured muscles, an extended interstitial network of CD34+ TCs/telopodes was detected around activated SCs displaying Pax7+ and MyoD+ nuclei. TEM revealed that TCs invaded the SC niche passing with their telopodes through a fragmented basal lamina and contacting the underlying activated SCs. TC-SC interaction after injury was confirmed in vitro by culturing single endomysial sheath-covered myofibers and sprouting TCs and SCs. EC-damaged muscle-derived TCs showed increased expression of the recognized pro-myogenic vascular endothelial growth factor-A, and SCs from the same samples exhibited increased MyoD expression and greater tendency to fuse into myotubes. Here, we provide the essential groundwork for further investigation of TC-SC interactions in the setting of skeletal muscle injury and regenerative medicine.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Morphological evidence for telocytes as stromal cells supporting satellite cell activation in eccentric contraction-induced skeletal muscle injury

Manetti

Tani

Rosa

et al. 2019

Sci Rep

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“…We also observed that the peritubular CD34-negative/α-SMA-positive myoid cells/myofibroblasts coexpress PDGFRα, which further strengthen the evidence that single immunohistochemistry is not enough and can lead to misleading results when studying TCs by light microscopy. Since the expression of the stemness-related marker c-kit/CD117 has been reported in TCs from some tissues and organs, such as in the heart, skeletal muscles and female reproductive system 6 , 7 , 12 , 14 , 16 , 59 , we also double immunolabeled our human testicular sections for CD34/c-kit. Hence, we found that human testicular TCs are c-kit/CD117-negative, as previously documented in other human organs including the gastrointestinal tract and the skin 36 , 52 .…”

Section: Discussionmentioning

confidence: 99%

Reappraising the microscopic anatomy of human testis: identification of telocyte networks in the peritubular and intertubular stromal space

Marini

Rosa

Guasti

et al. 2018

Sci Rep

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Telocytes are a recently described stromal cell type widely distributed in various organs including the female and male reproductive systems. This study was aimed to investigate for the first time the existence, distribution and characteristics of telocytes in normal human testis by an integrated morphological approach (immunohistochemistry, immunofluorescence and transmission electron microscopy). We found that telocytes displaying typical long and moniliform prolongations and coexpressing CD34 and PDGFRα formed networks in the outer layer of peritubular tissue and around Leydig cells and vessels in the intertubular stroma. Testicular telocytes were immunophenotypically negative for CD31, c-kit/CD117 as well as α-SMA, thus making them clearly distinguishable from myoid cells/myofibroblasts located in the inner layer of peritubular tissue. Transmission electron microscopy confirmed the presence of cells ultrastructurally identifiable as telocytes (i.e. cells with telopodes alternating podomers and podoms) in the aforementioned locations. Intercellular contacts between neighboring telocytes and telopodes were observed throughout the testicular stromal compartment. Telopodes intimately surrounded and often established close contacts with peritubular myoid cells/myofibroblasts, Leydig cells and vessels. Extracellular vesicles were also frequently detected near telopodes. In summary, we demonstrated that telocytes are a previously neglected stromal component of human testis with potential implications in tissue homeostasis deserving further investigation.

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“…In addition, several tumors can have their origin in CD34+SCs/TCs [ 32 , 33 , 34 ]. In the skin, the suggested roles of CD34+SCs/TCs include mechanical support, regeneration (tandem between TCs and stem cells), communication (intercellular contacts and extracellular vesicles) and endocytosis, immune regulation, modulation of fibroblasts, mast cells and macrophages, reduction of inflammatory response, participation in metabolism, homeostasis, (neo) angiogenesis and in the interaction between collagen and elastic fibers [ 3 , 4 , 13 , 14 , 15 , 18 , 22 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ].…”

Section: Introductionmentioning

confidence: 99%

Cd34+ Stromal Cells/Telocytes in Normal and Pathological Skin

Gutiérrez

García

González‐Gómez

et al. 2021

IJMS

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We studied CD34+ stromal cells/telocytes (CD34+SCs/TCs) in pathologic skin, after briefly examining them in normal conditions. We confirm previous studies by other authors in the normal dermis regarding CD34+SC/TC characteristics and distribution around vessels, nerves and cutaneous annexes, highlighting their practical absence in the papillary dermis and presence in the bulge region of perifollicular groups of very small CD34+ stromal cells. In non-tumoral skin pathology, we studied examples of the principal histologic patterns in which CD34+SCs/TCs have (1) a fundamental pathophysiological role, including (a) fibrosing/sclerosing diseases, such as systemic sclerosis, with loss of CD34+SCs/TCs and presence of stromal cells co-expressing CD34 and αSMA, and (b) metabolic degenerative processes, including basophilic degeneration of collagen, with stromal cells/telocytes in close association with degenerative fibrils, and cutaneous myxoid cysts with spindle-shaped, stellate and bulky vacuolated CD34+ stromal cells, and (2) a secondary reactive role, encompassing dermatitis—e.g., interface (erythema multiforme), acantholytic (pemphigus, Hailey–Hailey disease), lichenoid (lichen planus), subepidermal vesicular (bullous pemphigoid), psoriasiform (psoriasis), granulomatous (granuloma annulare)—vasculitis (leukocytoclastic and lymphocytic vasculitis), folliculitis, perifolliculitis and inflammation of the sweat and sebaceous glands (perifolliculitis and rosacea) and infectious dermatitis (verruca vulgaris). In skin tumor and tumor-like conditions, we studied examples of those in which CD34+ stromal cells are (1) the neoplastic component (dermatofibrosarcoma protuberans, sclerotic fibroma and solitary fibrous tumor), (2) a neoplastic component with varying presentation (fibroepithelial polyp and superficial myxofibrosarcoma) and (3) a reactive component in other tumor/tumor-like cell lines, such as those deriving from vessel periendothelial cells (myopericytoma), epithelial cells (trichoepithelioma, nevus sebaceous of Jadassohn and seborrheic keratosis), Merkel cells (Merkel cell carcinoma), melanocytes (dermal melanocytic nevi) and Schwann cells (neurofibroma and granular cell tumor).

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Ultrastructural and immunohistochemical characteristics of telocytes in the skin and skeletal muscle of newborn rats

Cited by 13 publications

References 57 publications

Morphological evidence for telocytes as stromal cells supporting satellite cell activation in eccentric contraction-induced skeletal muscle injury

Morphological evidence for telocytes as stromal cells supporting satellite cell activation in eccentric contraction-induced skeletal muscle injury

Reappraising the microscopic anatomy of human testis: identification of telocyte networks in the peritubular and intertubular stromal space

Cd34+ Stromal Cells/Telocytes in Normal and Pathological Skin

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