<scp>FIB</scp>‐<scp>SEM</scp> tomography of human skin telocytes and their extracellular vesicles

<jats:title>Abstract</jats:title><jats:p>We have shown in 2012 the existence of telocytes (<jats:styled-content style="fixed-case">TC</jats:styled-content>s) in human dermis. <jats:styled-content style="fixed-case">TC</jats:styled-content>s were described by transmission electron microscopy (<jats:styled-content style="fixed-case">TEM</jats:styled-content>) as interstitial cells located in non‐epithelial spaces (stroma) of many organs (see <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.telocytes.com">www.telocytes.com</jats:ext-link>). <jats:styled-content style="fixed-case">TC</jats:styled-content>s have very long prolongations (tens to hundreds micrometers) named Telopodes (Tps). These Tps have a special conformation with dilated portions named podoms (containing mitochondria, endoplasmic reticulum and caveolae) and very thin segments (below resolving power of light microscopy), called podomers. To show the real 3D architecture of <jats:styled-content style="fixed-case">TC</jats:styled-content> network, we used the most advanced available electron microscope technology: focused ion beam scanning electron microscopy (<jats:styled-content style="fixed-case">FIB</jats:styled-content>‐<jats:styled-content style="fixed-case">SEM</jats:styled-content>) tomography. Generally, 3D reconstruction of dermal <jats:styled-content style="fixed-case">TC</jats:styled-content>s by <jats:styled-content style="fixed-case">FIB</jats:styled-content>‐<jats:styled-content style="fixed-case">SEM</jats:styled-content> tomography revealed the existence of Tps with various conformations: (<jats:italic>i</jats:italic>) long, flattened irregular veils (ribbon‐like segments) with knobs, corresponding to podoms, and (<jats:italic>ii</jats:italic>) tubular structures (podomers) with uneven calibre because of irregular dilations (knobs) – the podoms. <jats:styled-content style="fixed-case">FIB</jats:styled-content>‐<jats:styled-content style="fixed-case">SEM</jats:styled-content> tomography also showed numerous extracellular vesicles (diameter 438.6 ± 149.1 nm, <jats:italic>n</jats:italic> = 30) released by a human dermal <jats:styled-content style="fixed-case">TC</jats:styled-content>. Our data might be useful for understanding the role(s) of <jats:styled-content style="fixed-case">TC</jats:styled-content>s in intercellular signalling and communication, as well as for comprehension of pathologies like scleroderma, multiple sclerosis, psoriasis, <jats:italic>etc</jats:italic>.</jats:p>