Telocytes in Human Term Placenta: Morphology and Phenotype

Abstract

In the last few years, a new cell type – interstitial Cajal-like cell (ICLC) – has been described in digestive and extra-digestive organs. The name has recently been changed to telocytes (TC) and their typical thin, long processes have been named telopodes (TP). To support the hypothesis that TC may also be present in human placenta and add to the information already available, we provide evidence on the ultrastructure, immunophenotype, distribution, and interactions with the surrounding stromal cells of TC in the villous core of human term placenta. We used phase-contrast microscopy, light microscopy of semithin sections, transmission electron microscopy, immunohistochemistry, and immunofluorescence of tissue sections or cell cultures, following a pre-established diagnostic algorithm. Transmission electron microscopy showed cells resembling TC, most (∼76%) having 2–3 very thin, longprocesses (tens to hundreds of micrometers), with an uneven calibre(≤0.5 µm thick) and typical branching pattern. The dilations of processes accommodate caveolae, endoplasmic reticulum cisternae, and mitochondria. These TC have close contacts with perivascular SMC in stem villi. In situ, similar cells are positive for c-kit, CD34, vimentin, caveolin-1, vascular endothelial growth factor (VEGF), and inducible nitric oxide synathase (iNOS). The c-kit-positive cells inconsistently co-express CD34, CD44, αSMA, S100, neuron-specific enolase, and nestin. Among cells with a morphologic TC profile in cell cultures, about 13% co-express c-kit, vimentin, and caveolin-1; 70% of the c-kit-positive cells co-express CD34 and 12% co-express iNOS or VEGF. In conclusion, this study confirms the presence of TC in human term placenta and provides their ultrastructural and immunophenotypic characterization.

Telocytes of the mammary gland stroma

“…They were not searched then for the CD34 expression. It was documented that, in human chorial villi, some TCs are CD34-positive, some are c-kit-positive [15,41]. Here a CD34-positive but c-kit-negative phenotype was found.…”

Ultrastructural identification of telocytes in the muscularis of chicken ileum

“…F, fibroblast; N, nucleus; Nf, nerve fiber; Pd, podomer; Pm, podom; SMC, smooth muscle cell; Tc, telocyte; Tp, telopode. reporting the presence of TCs in other organs, including the epicardium (20), myocardium (21), endocardium (26), placenta (27) and skin (28). The role of TCs is unclear; however, based on the available data, numerous potential and relevant roles have been proposed.…”

“…Manole et al (36) demonstrated that TCs are involved in neo-angiogenesis in experimental acute myocardial infarction. TCs may further be involved in tissue regeneration and reparation (28,18); it is suggested that TCs are involved in angiogenesis, as it has been demonstrated that TCs express CD34 and VEGF (27).…”

A comprehensive guide to telocytes and their great potential in cardiovascular system

“…They are connected with each other through gap junctions or desmosomes (45,47,49). TCs accompanying capillaries frequently establish heterocellular contacts with pericytes and endothelial cells.…”

“…Such phenomenon was observed in human term placenta, where TCs form a network around myofi broblasts and VSMCs. This regulatory mechanism may include NO signalisation, since some of the network-forming TCs expressed iNOS (49).…”