Telocytes

AbstractHere, we review the history, morphology, immunohistochemical phenotype, and presumptive roles of a new type of interstitial tissue cells, formerly called interstitial Cajal-like cells (ICLC) and by 2010 named 'telocytes' (TC). Many different techniques have been used to characterize TC and provide their unequivocal identification: (i) in vitro, cultures and isolated cells; (ii) in situ, fixed specimens examined by light and fluorescence microscopy, transmission (TEM) and scanning electron microscopy, and electron tomography. TEM allowed sure identification and characterization of the most peculiar feature of TC: the long, thin, and convoluted prolongations named 'telopodes'. An enormous variety of antibodies have been tested, but presently none are reliable to specifically label TC. TC have a mesenchymal origin and are resident connective tissue (stromal) cells. Possible identification with 'already identified' stromal cell types (fibroblasts, fibrocytes, fibroblast-like cells, and mesenchymal stromal cells) is discussed. We conclude that in adulthood, most of the TC have the morphology of fibrocytes. Apparently, immunocytochemistry suggests that a variety of TC populations showing different, likely organ-specific, immunophenotypes might exist. Several roles have been hypothesized for TC: mechanical roles, intercellular signaling, guiding and nursing of immature cells during organogenesis, and being themselves a pool of precursors for many of the mesenchyme-derived cells in adulthood; however, none of these roles have been proven yet. On the basis of the available data, we propose TC may be key players in organ regeneration and repair

NK-receptors, Substance P, Ano1 expression and the ultrastructural features of the muscle coat are modified in the Cav-1-/- mouse ileum

Caveolin (Cav)-1 is an integral membrane protein of caveolae playing a crucial role in various signal transduction pathways. Caveolae represent the sites for calcium entry and storage especially in smooth muscle cells (SMC) and interstitial cells of Cajal (ICC). Cav-1-/- mice lack caveolae and show abnormalities in pacing and contractile activity of the small intestine. In particular, the absence of caveolae in ICC compromised their ability to maintain frequencies of contraction. Presently, we investigated, by transmission electron microscopy (TEM) and immunohistochemistry, whether the absence of Cav-1 in Cav-1-/- mouse small intestine affects ICC, SMC and neuronal morphology, the expression of NK1 and NK2 receptors, and of Ano1 (also called Dog1 or TMEM16A) an essential molecule for slow wave activity in gastrointestinal muscles. ICC were also labeled with c-Kit and tachykinergic neurons with Substance P (SP). Immunohistochemical results showed that in Cav-1-/- mice: i) ICC were Ano1-negative but maintained c-Kit expression, ii) NK1 and NK2 receptor immunoreactivity was increased and, in the SMC, mainly intracytoplasmatic, iii) SP-immunoreactivity was significantly reduced. Under TEM: i) ICC and SMC lacked typical caveolae but had few and large flask-shaped vesicles we called large-sized caveolae; ii) SMC and ICC contained an extraordinary high number of mitochondria; iii) neurons were unchanged. In conclusion, the present study shows important changes in SMC, ICC and neurons of the Cav-1-/- mice. Loss of Ano1 expression in the ICC and rearrangement of NK receptors in the SMC are interpretable as consequence of Cav-1/caveolae loss and possibly responsible for the impaired contractile activity. However, the impressive richness in mitochondria and the decrease in SP content might represent the ways to compensate the reduced calcium availability and the increased expression of NKr, allowing the maintenance of a certain cell function

From conception to birth: ancient library sources of embryology and women anatomy kept in the Biblioteca Biomedica of the Università degli Studi di Firenze (Biomedical Library of Florence University)

The Biomedical Library of the University of Florence boasts a prestigious group of books collected at first in 1679 at the hospital “Santa Maria Nuova” and then continuously enriched in the course of time up today. The “Antique Collection” consists of 13 incunabola, hundreds of 16th-century books, more than one thousand books on medical subject from the 1600’s, about six thousand 18th-century volumes and several large, valuable anatomical atlases. In this paper the most important, curious and fascinating books dealing with human ontogeny (from embryo generation to birth) and with female anatomy (mostly concerning pregnancy and childbirth) are reported in chronological order starting from the work of Hippocrates. Among the ancient sources useful for the reconstruction of the opinions about obstetrics there are also outstanding handbooks specifically edited for midwives. Many of these antique books are especially precious because they embed a great number of didactic pictures, some of which may compete against any modern book of anatomy, embryology and obstetric. Selected images from these books are shown

The wrap partial restrain stress, an animal model of the irritable bowel syndrome: immunohistochemical and functional characterization

Several animal models have been proposed to mimic the human irritable bowel syndrome (IBS) all based on two etio-pathogenic hypotheses: infection and stress, both responsible for the development of a local inflammation. We investigated the wrap partial restrain stress (WRS) animal model with the aim to evaluate its validity in understanding the human IBS. Male Wistar rats were used and WRS was maintained for 2h. Abdominal contractions (AC) were recorded by a distension balloon in the colon-rectum. The number of faecal pellets and their total weight were determined. Colonic specimens from both groups were examined by routine histology, immunohistochemistry and western blot (WB). WRS animals were characterized by: 1) a statistically significant increase in the number of AC and in the mean number and mean weight of faecal pellets; 2) the presence of large clusters of mononucleated cells and a significant increase in eosinophilic granulocytes and mast cells in the mucosa; 3) reduction of GLP1r-immunoreactivity (IR) located at the basolat- eral periphery and the Golgi level of the cells of the glandular funds; 4) an increase in CGRP-IR in the lamina propria; 5) no significant difference in the muscle wall for Cav1, L- type Ca+2-channels, Mr2, NK1r and NK2r; 6) a significant decrease in the myenteric and a significant increase in the submucous NK1-IR neuron number; 7) a significant decrease in Substance P-IR in the myenteric plexus and muscle coat; 8) a significant decrease in myenteric and submucous nNOS-IR neuron number; 9) no difference in ChAT-IR neurons of both enteric plexuses; 10) a reduction in S-100-IR in the entire colonic wall; 11) no difference in the total number of neurons evaluated by the pan-neuronal marker PGP 9.5; 12) no change of all the ICC populations. The functional data are in favor of a lowering in the colonic wall distention threshold; the morphological results obtained in the lamina propria demonstrate the presence of a local inflammation, particularly intense at the level of the mucosa. Both of these findings agree with the hypothesis that inflammation might have a main role in the insurgence and maintenance of the typical IBS symptoms and support the validity of our WRS model. Moreover, while the smooth muscle cells do not show any significant variation, numerous and consistent changes in the excitatory, inhibitory and NK1r-IR neurons are detected

Telocytes: New Connecting Devices in the Stromal Space of Organs

Telocytes (TCs) represent a new type of interstitial cells, and were discovered by Prof. Popescu and his collaborators from Bucharest in 2005, and described as Interstitial Cajal-Like Cells (ICLCs). In 2010, Prof. Popescu and Prof. Faussone-Pellegrini from Florence, based on their expertise in morphology, agreed that in fact ICLCs were a brand-new entity and they renamed them telocytes. TCs are characterized by specific veil- or ribbon-like extensions called telopodes. Telopodes aid TCs in forming homo- or hetero-cellular contacts; thus, assembling three-dimensional networks that organizes the stromal and the parenchymal components of the organs. TCs can transfer information to neighbor cells ensuring a short-distance communication, and remotely by the release a wide variety of extracellular vesicles: exosomes, ectosomes, and multivesicular bodies. Here, we reviewed the evolution of the interest regarding TCs in different organs, in normal and pathological conditions. The main focus was on the role of TCs in gastrointestinal tract, urinary bladder, reproductive tract, and heart. This chapter sums up information about the possibilities that TCs are capable to behave as sensors/mediators in nervous activity, to represent mesenchymal stem cell precursors in adulthood, and to control and determine the differentiation/maturation of other cell types either during development or in postnatal life

Adaptive changes of telocytes in the urinary bladder of patients affected by neurogenic detrusor overactivity

Urinary bladder activity involves central and autonomic nervous systems and bladder wall. Studies on the pathogenesis of voiding disorders such as the neurogenic detrusor overactivity (NDO) due to supra-sacral spinal cord lesions have emphasized the importance of an abnormal handling of the afferent signals from urothelium and lamina propria (LP). In the LP (and detrusor) three types of telocytes (TC) are present and form a 3D-network. TC are stromal cells able to form the scaffold that contains and organizes the connective components, to serve as guide for tissue (re)-modeling, to produce trophic and/or regulatory molecules, to share privileged contacts with the immune cells. Specimens of full thickness bladder wall from NDO patients were collected with the aim to investigate possible changes of the three TC types by using histology, immunohistochemistry and transmission electron microscopy. The results show that NDO causes several morphological TC changes without cell loss or network interruption. With the exception of those underlying the urothelium, all the TC display signs of activation (increase in Caveolin1 and caveolae, SMA and thin filaments, Calreticulin and amount of cisternae of the rough endoplasmic reticulum, CD34, euchromatic nuclei and large nucleoli). In all the specimens a cell infiltrate, mainly consisting in plasma cells located in the vicinity or taking contacts with the TC, is present. In conclusion, our findings show that NDO causes significant changes of all the TC. Notably, these changes can be interpreted as TC adaptability to the pathological condition likely preserving each of their peculiar functions

Chronic treatment with otilonium bromide affects the tachykinergic and nitrergic systems in the rat colon

Otilonium bromide (OB), a quaternary ammonium derivative used for the treatment of intestinal motility disorders such as the irritable bowel syndrome (IBS). It exerts several actions, among which the ability to bind to the neurokin-2 receptor (NK2r) inhibiting NK2r mediated contraction and, in the human colon, NK2r internalization in the smooth muscle cells (SMC) (Cipriani et al., 2011). Substance P (SP) is an excitatory neurotransmitter that, interacting mainly with the neurokinin-1 receptor (NK1r), can stimulate bowel motility by SMC direct activation or inhibit it by an indirect action through enteric neural circuits. In an IBS rat model, the increase in NK1rmediated colonic motor response was associated to a decrease in the nitrergic activity. On these basis, we tested whether OB modifies NK1r, NK2r, SP and neuronal nitric oxide synthase (nNOS) expression in rat colon after chronical administration of the drug (2 or 20mg/Kg/daily) for 10 or 30 days. At the end of the treatments, specimens of proximal colon were collected and the expression of NK1r, NK2r, SP and neurogenic and myogenic nNOS were evaluated by immunohistochemistry and Western blot. Our data show that SP expression was significantly decreased in 10 and 30 days treated rats in myenteric ganglia and, in 30 days treated rats, also in the intramuscular nerve fibres. No quantitative change of the two NKr was observed, whereas, after 30 days, the NK1r was concentrated in the SMC cytoplasm. In parallel, the neurogenic nNOS expression increased and reached the significance after 30 days of treatment; the myogenic nNOS expression increased, but these increase reached the significance only at 10 days. Our findings suggest that the main target of the OB chronically administered is the NO-mediated system that is stimulated earlier at the muscular level, later at the neuronal level. We interpret the systemic decrease in the SP expression as consequence of the potentiated NO availability in the ganglia and muscle coat. If true, the late concentration of NK1r in the cytoplasm could represent an attempt of the SMC to overcome the deficit of its main ligand SP

Inner and outer portions of colonic circular muscle: ultrastructural and immunohistochemical changes in rat chronically treated with Otilonium Bromide

Rat colonic circular muscle layer (cml), main target of otilonium bromide (OB) spasmolytic activity [1], is subdivided in an inner (icl) and an outer (icl) portion. The icl is particularly rich in organelles such as caveolae, smooth endoplasmic reticulum, mitochondria [2]. The expression of specific markers in comparison with the ocl was investigated. The possible changes of these organelles and related markers, and of muscarinic receptors (Mr2) were studied after OB chronic exposition (2-20mg/kg for 10 or 30 days). Colon specimens were processed for electron microscopy, immunohistochemistry and western blot. In colonic strips the contractility response to Mr2 agonist was investigated. The results show that in controls the icl displays a higher expression of Caveolin-1 and Mr2, but not of eNOS, calreticulin and calsequestrin, compared to ocl. Chronic OB treatment caused similar ultrastructural and immunohistochemical changes in both portions. Organelles, Caveolin-1 and eNOS were increased at 10 days; Mr2 expression and muscle contractility induced by metacholine were increased at 30 days. Our findings 1) provide new information on the immunohistochemical properties of the icl suggesting a distinct role for this portion in colonic motility; 2) demonstrate that chronically administered OB interferes with cell structures and molecules responsible for calcium handling and storage, and modifies cholinergic transmission