Skin telocytes versus fibroblasts: two distinct dermal cell populations

Abstract

It is already accepted that telocytes (TCs) represent a new type of interstitial cells in human dermis. In normal skin, TCs have particular spatial relations with different dermal structures such as blood vessels, hair follicles, arrector pili muscles or segments of sebaceous and/or eccrine sweat glands. The distribution and the density of TCs is affected in various skin pathological conditions. Previous studies mentioned the particular (ultra)structure of TCs and also their immunophenotype, miR imprint or proteome, genome or secretome features. As fibroblast is the most common intersitital cell (also in human dermis), a dedicated comparison between human skin TCs and fibroblasts (Fbs) was required to be performed. In this study, using different techniques, we document several points of difference between human dermis TCs and Fbs. By transmission electron microscopy (TEM) and scanning electron microscopy (SEM), we demonstrated TCs with their hallmark cellular prolongations – telopodes. Thus, we showed their ultrastructural distinctiveness from Fbs. By RayBio Human Cytokine Antibody Array V analyses performed on the supernatant from separately cultured TCs and Fbs, we detected the cytokine profile of both cell types, individually. Two of 79 detected cytokines – epithelial-derived neutrophil-activating peptide 78 and granulocyte chemotactic protein-2 – were 1.5 times higher in the supernatant of TCs (comparing with Fbs). On the other hand, 37 cytokines were at least 1.5 higher in Fbs supernatant (comparing with TCs), and among them six cytokines – interleukin 5, monocyte chemotactic protein-3 (MCP-3), MCP-4, macrophage inflammatory protein-3, angiogenin, thrombopoietin – being 9.5 times higher (results also confirmed by ELISA testing). In summary, using different techniques, we showed that human dermal TCs and Fbs are different in terms of ultrastructure and cytokine profile.

Telocytes in normal and keratoconic human cornea: an immunohistochemical and transmission electron microscopy study

“…In the last years, numerous studies have shown the existence of a novel and peculiar stromal cell type, the TC, in many different organs and tissues of vertebrates including laboratory mammals and humans [10][11][12][13][14][15][16][17][18][19][20][21][22]. As far as the ocular system is concerned, a recent report described the presence of TC in the limbus, sclera and uvea of the mouse eye [50].…”

“…A new type of interstitial cells, named telocytes (TC), has been recently described in the stromal compartment of many organs in vertebrates including humans [10][11][12][13][14][15][16][17][18][19][20][21][22]. Moreover, this peculiar stromal cell type is being increasingly implicated in a wide range of pathologies with potential applications in regenerative medicine [23][24][25][26][27][28][29][30][31][32][33][34][35][36].…”

How hormones may modulate human skin pigmentation in melasma: An in vitro perspective

“…These cells are probably telocytes (interstitial Cajal‐like cell (ICLC), CD34 + stromal cells or CD34 + fibrocytes). Telocytes are localized in the papillary dermis just beneath the basement membrane, around blood vessels and surrounding sebaceous glands, expressed oestrogen and progesterone receptors in vitro and seemed to play a role in angiogenesis and tissue homeostasis . Indeed, they secrete extracellular vesicles which allow communication with neighbouring cells such as fibroblasts, immune cells nerve endings and endothelial cells .…”

Ultrastructural and immunohistochemical characteristics of telocytes in human scalp tissue

“…In recent years, researchers have used focused ion beam scanning electron microscopy to investigate the 3D imaging of TCs in human dermis, and have revealed the existence of Tps with various conformations: (i) long, flattened irregular veils (ribbon-like segments) with knobs, corresponding to podoms, and (ii) tubular structures (podomers) with uneven calibre because of irregular dilations (knobs) -the podoms 10 . So far, TCs have been detected in many tissues and organs, including the heart 11,12 , lung 13,14 , skeletal muscle 15 , skin 16,17 , eye 18,19 , liver 20 , uterus 21 and urinary system 22,23 .…”