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Objective(s): Gallbladder interstitial Cajal-like cells (ICLCs) are known as some of the players in the complex motility mechanisms affecting gallbladder motility. This study aims to explore the mechanism of guinea-pig gallbladder motility disorders during Acute Cholecystitis (AC), focusing on the relationships between neutrophil alterations, gallbladder ICLCs, and smooth muscle contractility.Materials and Methods: Forty-eight guinea pigs were randomly divided into four groups: normal, sham, common bile duct ligation (CBDL), and anti-PMN (anti-polymorphonuclear antibody treated +CBDL). Hematoxylin and eosin-stained slides from each gallbladder sample were examined for inflammation, and myeloperoxidase (MPO) activity was evaluated. The contractile response of gallbladder muscle to Ach, CCK-8, and KCl was registered by a tension transducer, and ultrastructure features of ICLCs were observed.Results: Pretreatment with anti-PMN significantly reduced the circulating neutrophils by 80% and also considerably decreased the gallbladder MPO activity by 52.9% compared with the CBDL group (P

Introduction: Telocytes (TCs), also called interstitial Cajal-like cells (ICLC), CD34+ cells or PDGFRα+ cells (platelet-derived growth factor receptor α positive cells), a new type of cell of mesenchymal origin, were described over one decade ago. The unique nature of these cells still deserves attention from the scientific community. Telocytes make homo- and heterocellular contact with myocytes, immunocytes and nerves, have their own immunohistochemical and secretome profiles and thus might regulate local regenerative processes including angiogenesis and fibrosis. The aim of our study was to observe the missing link between angiogenesis and telocytes in leiomyoma, the most common benign tumors affecting women of reproductive age.Material and methods: We observed uterine tissue samples from leiomyoma, adjacent myometrium and unchanged tissue from patients with leiomyoma and control subjects using routine histology, histochemistry, immunofluorescence (CD117, CD31, CD34, PDGFRα, tryptase, sFlt-1) and image analysis methods.Results: The decline of the telocyte density in the foci of fibroids correlated with poor vascularization inside the leiomyoma. Moreover, the expression of sFlt-1 (anti-angiogenic-related factor) significantly increased inside a fibroid. In leiomyoma the decrease of telocyte and blood micro-vessel density was accompanied by prevalence of collagen deposits, unlike the unchanged myometrium.Conclusions: Our results demonstrate TCs in human uterine fibroids and highlight their possible involvement in the pathogenesis of myometrial pathology in the context of angiogenesis. [ABSTRACT FROM AUTHOR]

Background: Idiopathic or unexplained infertility is a broad subcategory of infertility defined by the absence of obvious or explainable cause, but accounts for at least 25% of all causes. Many possible hidden factors have been discussed over the years, but one of the most prominent and controversial players in this area recently, have been telocytes—newly discovered interstitial cells. Telocytes were first described only 15 years ago, but as of today, they have been observed in almost all organs of the human body including the uterine tubes, uterus and other organs of the female reproductive system. Aside from their vast array of physiological functions such as immune regulation, cell-to-cell signalling, cell-nursing and hormone-sensing, they have been also implicated in the pathogenesis of many different diseases, for which we have coined an original term “telocytopathies”. Methods: We have reviewed relevant articles in English on the topic of idiopathic infertility and telocytes mostly from the last 5 years, using PubMed/MEDLINE, Scopus and Web of Science databases. Results: Quantitative loss and functional derangement of telocytes many not cause any obvious pathological changes, but a subtle, yet important loss of crucial functions of telocytes can lead to unexplained infertility. Discussion: In the uterine tubes, possible mechanisms include changes in the structural and functional integrity of the cellular microenvironment. In the uterus, one of the main proposed mechanisms is immune dysregulation of macrophages and other immune cell populations. In the developing placenta, the main focus is placed on the role of telocytes in immune regulation and decidualisation. All these presupposed pathogenetic factors are still highly speculative, but possibly future research will elucidate the role of telocytes in these processes, which may lead to change of the status of idiopathic infertility, but also of many other “idiopathic” diseases regardless of the organ in question.

Interstitial cells of Cajal (ICCs) are a special type of interstitial cells located in the gastrointestinal tract muscles. They are closely related to smooth muscle cells and neurons, participate in gastrointestinal motility and nerve signal transmission, and are pacemaker cells for gastrointestinal electrical activity. Research interest in ICCs has continuously grown since they were first discovered in 1893. Later, researchers discovered that they are also present in other organs, including the biliary tract, urethra, bladder, etc.; these cells were named interstitial Cajal-like cells (ICLCs), and attempts have been made to explain their relationships with certain diseases. This review paper summarizes the morphology, identification, classification, function, and distribution of ICLCs in the biliary tract and their relationship to biliary tract diseases. Based on the function and distribution of ICLCs in the biliary tract system, ICLCs will provide a more reliable theoretical basis for the mechanisms of pathogenesis of and treatments for biliary tract diseases. [ABSTRACT FROM AUTHOR]

Acute cholecystitis is a common disease with gallbladder dysmotility. Disease pathogenesis involves immune cell infiltration as well as changes in gallbladder interstitial Cajal‐like cells (ICLCs). However, it remains unclear if or how the immune cells affect ICLC morphology, density, distribution, and function in gallbladder tissue during acute cholecystitis. In this study, we explored the acute cholecystitis‐related alterations in gallbladder ICLCs in a guinea pig model, focusing on the effects of neighboring neutrophils. Adult guinea pigs were randomly divided into four groups (control, 24 hr common bile duct ligation [CBDL], 48‐hr CBDL, and antipolymorphonuclear neutrophil [PMN] treated) and analyzed using methylene blue staining and immunofluorescence. Gallbladder contractility was also monitored. To culture gallbladder ICLCs, collagenase digestion was performed on tissue from 10‐ to 15‐day‐old guinea pigs. Neutrophils isolated from the peripheral blood of experimental animals 48‐hr postsurgery were also cocultured with the gallbladder ICLCs. Intracellular calcium was detected with Fluo‐4 AM dye. Our results showed that gallbladder ICLC density significantly declined during acute cholecystitis and was accompanied by shortening of the cellular processes and damage to their network‐like structure. However, pretreatment with anti‐PMN partially prevented these changes. Gallbladder contraction was also significantly decreased during acute cholecystitis, and this appeared to be mediated by the neutrophils. Moreover, ICLCs cocultured with neutrophils also had shortened and reduced processes and impaired network‐like structure formation. Intracellular calcium transient was less sensitive to contraction agonists and inhibitors when cocultured with neutrophils. Taken together, neutrophils greatly affect gallbladder ICLCs and dysmotility during acute cholecystitis. In conclusion, we have demonstrated that neutrophils greatly affect ICLC morphology, distribution, and function in a guinea pig model of acute cholecystitis. During disease, ICLCs display multiple impairments both in their prolongations and network‐like structure, with obvious decreases in ICLC number and Ca2+ signaling, all of which appear to be, at least partially, mediated by neutrophils. [ABSTRACT FROM AUTHOR]

Introduction. A reduced number of interstitial Cajal-like cells (ICLCs) in the gallbladder have been proposed to play a role in the pathogenesis of cholelithiasis. Therefore, this prospective study was conducted to investigate the relationship between gallbladder contractility and the number of gallbladder ICLCs in patients with cholelithiasis. Material and methods. Patients admitted to the Department of Hepatobiliary Surgery for cholecystectomy were divided into the cholelithiasis (n = 18) and non-cholelithiasis (n = 8) groups based on their clinical data. Patients' clinical data were collected on admission, and B-mode ultrasonography was performed to assess their gallbladder contractility. The resected gallbladder specimens were fixed, paraffin sections mounted on slides, and the immunofluorescence staining with the anti-human CD-117 and anti-human tryptase antibodies was performed to identify ICLSs and mast cells, respectively. The number of ICLCs was counted in 10 high-power fields (HPFs) randomly. Results. Independent sample t-tests revealed differences between the cholelithiasis and non-cholelithiasis groups in the number of ICLCs (mean ± standard deviation: 88.61 ± 28.22 vs. 115.89 ± 27.87 per HPFs, P = 0.032) and gallbladder contractility (43.94% ± 18.50% vs. 61.00% ± 20.50%, P = 0.046). Pearson and Spearman correlation analyses revealed no significant correlation between the number of ICLCs and gallbladder contractility. Conclusion. The results suggest that the number of gallbladder ICLCs in the wall of the gallbladder of patients with or without cholelithiasis is not a decisive factor affecting gallbladder contractility. [ABSTRACT FROM AUTHOR]

Background: Acute cholecystitis is a common condition in gallbladder motility disorder. Interstitial Cajal-like cells (ICLCs) in the gallbladder are known as one of the players in the complex motility mechanisms affecting gallbladder motility. Aim: This study explored morphological symptoms and molecular mechanisms underlying gallbladder ICLC changes induced by acute cholecystitis. Materials and Methods: Fifteen adult guinea pigs were randomly divided into 3 groups: sham-operated group (healthy controls) and 2 experimental groups wherein these guinea pigs were subjected to common bile duct ligation to induce acute cholecystitis. Neutrophils were isolated from the peripheral blood of sham-operated animals and from the experimental animals at 24 and 48 h after surgery, and co-cultured with gallbladder ICLCs. The morphology of gallbladder ICLCs was examined by laser confocal immunofluorescence microscopy, TUNEL assay was used to detect apoptosis, and western blot and real-time PCR were performed to detect stem cell factor (SCF) and c-kit protein and mRNA expression, respectively. Results: No morphological differences in the gallbladder ICLCs were observed between single-culture and co-culture with healthy control neutrophil groups. However, the ICLCs in all co-culture groups with acute inflammation were impaired. In the co-culture groups, the rate of ICLC apoptosis was significantly higher than that in the single-culture group. SCF and c-kit protein and mRNA expression levels decreased in all co-culture groups as well. Conclusion: We demonstrated that the neutrophils are involved in gallbladder ICLC injury in acute cholecystitis cases and associated with gallbladder motility disorder.

Background: Many studies have shown that interstitial Cajal-like cell (ICLC) abnormalities are closely related to a variety of dynamic gastrointestinal disorders. ICLCs are pacemaker cells for gastrointestinal movement and are involved in the transmission of nerve impulses., Aim: To elucidate the expression profile and significance of cholecystokinin-A (CCK-A) receptors in ICLCs in the common bile duct (CBD), as well as the role of CCK in regulating CBD motility through CCK-A receptors on CBD ICLCs., Methods: The levels of tyrosine kinase receptor (c-kit) and CCK-A receptors in CBD tissues and isolated CBD cells were quantified using the double immunofluorescence labeling technique. The CCK-mediated enhancement of the movement of CBD muscle strips through CBD ICLCs was observed by a muscle strip contraction test., Results: Immunofluorescence showed co-expression of c-kit and CCK-A receptors in the CBD muscularis layer. Observations of isolated CBD cells showed that c-kit was expressed on the surface of ICLCs, the cell body and synapse were colored and polygonal, and some cells presented protrusions and formed networks adjacent to the CBD while others formed filaments at the synaptic terminals of local cells. CCK-A receptors were also expressed on CBD ICLCs. At concentrations ranging from 10 -6 mol/L to 10 -10 mol/L, CCK promoted CBD smooth muscle contractility in a dose-dependent manner. In contrast, after ICLC removal, the contractility mediated by CCK in CBD smooth muscle decreased., Conclusion: CCK-A receptors are highly expressed on CBD ICLCs, and CCK may regulate CBD motility through the CCK-A receptors on ICLCs., Competing Interests: Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article., (©The Author(s) 2023. Published by Baishideng Publishing Group Inc. All rights reserved.)

In recent years, the interstitial cells telocytes, formerly known as interstitial Cajal-like cells, have been described in almost all organs of the human body. Although telocytes were previously thought to be localized predominantly in the organs of the digestive system, as of 2018 they have also been described in the lymphoid tissue, skin, respiratory system, urinary system, meninges and the organs of the male and female genital tracts. Since the time of eminent German pathologist Rudolf Virchow, we have known that many pathological processes originate directly from cellular changes. Even though telocytes are not widely accepted by all scientists as an individual and morphologically and functionally distinct cell population, several articles regarding telocytes have already been published in such prestigious journals as Nature and Annals of the New York Academy of Sciences. The telocyte diversity extends beyond their morphology and functions, as they have a potential role in the etiopathogenesis of different diseases. The most commonly described telocyte-associated diseases (which may be best termed “telocytopathies„ in the future) are summarized in this critical review. It is difficult to imagine that a single cell population could be involved in the pathogenesis of such a wide spectrum of pathological conditions as extragastrointestinal stromal tumors (“telocytomas„), liver fibrosis, preeclampsia during pregnancy, tubal infertility, heart failure and psoriasis. In any case, future functional studies of telocytes in vivo will help to understand the mechanism by which telocytes contribute to tissue homeostasis in health and disease.

Key morphological discoveries in recent years have included the discovery of new cell populations inside the heart called cardiac telocytes. These newly described cells of the connective tissue have extremely long cytoplasmic processes through which they form functionally connected three-dimensional networks that connect cells of the immune system, nerve fibers, cardiac stem cells, and cardiac muscle cells. Based on their functions, telocytes are also referred to as "connecting cells" or "nurse cells" for cardiac progenitor stem cells. In this critical review, we provide a summary of the latest research on cardiac telocytes localized in all layers of the heart -- from the historical background of their discovery, through ultrastructural, immunohistochemical, and functional characterizations, to the application of this knowledge to the fields of cardiology, stem cell research, and regenerative medicine. [ABSTRACT FROM AUTHOR]

Background: Acute cholecystitis is a common condition in gallbladder motility disorder. Interstitial Cajal-like cells (ICLCs) in the gallbladder are known as one of the players in the complex motility mechanisms affecting gallbladder motility. Aim: This study explored morphological symptoms and molecular mechanisms underlying gallbladder ICLC changes induced by acute cholecystitis. Materials and Methods: Fifteen adult guinea pigs were randomly divided into 3 groups: sham-operated group (healthy controls) and 2 experimental groups wherein these guinea pigs were subjected to common bile duct ligation to induce acute cholecystitis. Neutrophils were isolated from the peripheral blood of sham-operated animals and from the experimental animals at 24 and 48 h after surgery, and co-cultured with gallbladder ICLCs. The morphology of gallbladder ICLCs was examined by laser confocal immunofluorescence microscopy, TUNEL assay was used to detect apoptosis, and western blot and real-time PCR were performed to detect stem cell factor (SCF) and c-kit protein and mRNA expression, respectively. Results: No morphological differences in the gallbladder ICLCs were observed between single-culture and co-culture with healthy control neutrophil groups. However, the ICLCs in all co-culture groups with acute inflammation were impaired. In the co-culture groups, the rate of ICLC apoptosis was significantly higher than that in the single-culture group. SCF and c-kit protein and mRNA expression levels decreased in all co-culture groups as well. Conclusion: We demonstrated that the neutrophils are involved in gallbladder ICLC injury in acute cholecystitis cases and associated with gallbladder motility disorder. [ABSTRACT FROM AUTHOR]

Background: Recently, gastrointestinal stromal tumors that have developed outside of the digestive tract have been reported. These tumors are collectively termed extra-gastrointestinal stromal tumors. Extra-gastrointestinal stromal tumors can also develop in the liver. Only eight case reports involving primary GIST of the liver have been published. We report a case and review the literature regarding this disease. Case presentation: A 70-year-old woman with a past history of gastric cancer visited our hospital for regular inspection. With extensive radiological imaging, a computed tomography scan revealed a mass with a size of 6.8 cm in the lateral segment of the liver. F-Fluoro-2-deoxyglucose positron emission tomography revealed no other malignancies except for the liver tumor. Because the lesion was suspected of being a primary malignant hepatic tumor, lateral segmentectomy was performed. The immunohistochemical analysis supported the diagnosis of gastrointestinal stromal tumors in the liver. The patient has had no evidence of recurrence during the 10-month follow-up period; imatinib chemotherapy was not administered. Conclusions: Primary hepatic gastrointestinal stromal tumors had no characteristics that distinguished them from ordinary tumors in imaging examinations. Primary gastrointestinal stromal tumors might have developed from interstitial Cajal-like cells. [ABSTRACT FROM AUTHOR]

Objectives: To investigate the effect of interstitial Cajal-like cells (ICLCs) on contraction of gallbladder muscle strips; and to analyze the changes of ICLCs during cholesterol gallstone formation in guinea pig. Methods: The cholesterol gallstone animal model was made by feeding guinea pig with high cholesterol diet (HCD). In vitro isolated gallbladder muscle strips were prepared. Gallbladder motility was assessed by the contraction frequency and amplitude of slow wave in response to CCK-8. The alteration in ICLC density was estimated by using immunohistochemistry. The expression of c-kit and stem cell factor (SCF) were determined. Results and Conclusions: The amplitude and frequency of slow wave was significantly lower in gallbladder muscle strips with the impaired ICLCs. And it is correlated with the decreased contractile response to CCK-8. In HCD guinea pig, the ICLC density and bile flow in response to CCK-8 were remarkably decreased. The results indicated that gallbladder ICLCs can create slow wave potential, and also get involved in the regulation of CCK-8 induced gallbladder smooth muscle motility. In the process of cholesterol gallstone formation, ICLC density clearly decreased. This further impaired gallbladder motility. The decrease in ICLC density may result from decreased expression of c-kit and SCF during cholesterol gallstone formation. [ABSTRACT FROM AUTHOR]

Gall-stone disease constitutes a serious clinical problem and is the most frequent cause of elective cholecystectomies. There are many etiopatogenic factors however; lithogenic bile and its stasis due to gall-bladder hypomotility seem to be the most important. In recent years discovery of pacemaker function of Interstitial Cells of Cajal changed our understanding of smooth muscle physiology and helped to disclose many gastrointestinal motility disorders. The aim of the study was identification and quantification of interstitial Cajal-like cells (ICLCs) in gall-bladder muscle wall from patients with cholelithiasis and in gall-stone-free controls, as well as determination of the relationship between the number of ICLCs and Cholesterol Saturation Index (CSI) of bile in both analyzed groups. Material and methods. 20 patients operated for symptomatic cholelithiasis were enrolled into the study group. The control group consisted of 20 patients operated for pancreatic head tumors, with no pre- and intraoperative signs of gall-stones. Identification of ICLCs in the gall-bladder was performed by means of double immunofluorescence technique with anti c-Kit and anti-mast cell tryptase antibodies. Quantitative analysis was carried out under fluorescence microscopy conjoined with image analysis software. Bile samples were used for calculation of CSI. Results. ICLCs were detected within gall-bladder muscle wall. Number of ICLCs was statistically significantly lower in patients from the study group as compared to control. The study also revealed statistically significantly higher CSI in the study group. Conclusions. The quantity of ICLCs is diminished in the gall-bladder from patients with cholelithiasis and there is negative correlation between the number of ICLCs and CSI of bile. Regarding the role of ICCs in regulation of GI tract motility, it appears that reduction in their number may be important etiopatogenic factor of cholelithiasis. [ABSTRACT FROM AUTHOR]

The major mechanisms of gallstone formation include biliary cholesterol hypersecretion, supersaturation and crystallization, mucus hypersecretion, gel formation and bile stasis. Gallbladder hypomotility seems to be a key event that triggers the precipitation of cholesterol microcrystals from supersaturated lithogenic bile. Telocytes, a new type of interstitial cells, have been recently identified in many organs, including gallbladder. Considering telocyte functions, it is presumed that these cells might be involved in the signalling processes. The purpose of this study was to correlate the quantity of telocytes in the gallbladder with the lithogenicity of bile. Gallbladder specimens were collected from 24 patients who underwent elective laparoscopic cholecystectomy for symptomatic gallstone disease. The control group consisted of 25 consecutive patients who received elective treatment for pancreatic head tumours. Telocytes were visualized in paraffin sections of gallbladders with double immunofluorescence using primary antibodies against c-Kit (anti- CD117) and anti-mast cell tryptase. Cholesterol, phospholipid and bile acid levels were measured in gallbladder bile. The number of telocytes in the gallbladder wall was significantly lower in the study group than that in the control group (3.03 ± 1.43 versus 6.34 ± 1.66 cell/field of view in the muscularis propria, P < 0.001) and correlated with a significant increase in the cholesterol saturation index. The glycocholic and taurocholic acid levels were significantly elevated in the control subjects compared with the study group. The results suggest that bile composition may play an important role in the reduction in telocytes density in the gallbladder. [ABSTRACT FROM AUTHOR]

Interstitial Cajal-like cells (ICLCs) are speculated to be pacemakers in smooth muscle tissues. While the human thoracic duct (TD) is spontaneously active, the origin of this activity is unknown. We hypothesized that ICLCs could be present in the TD and using histological techniques, immunohistochemistry and immunofluorescence we have investigated the presence of ICLCs, protein markers for ICLCs and the cellular morphology of the human TD. Transmission electron microscopy was employed to investigate ultrastructure. Methylene blue staining, calcium-dependent fluorophores and confocal microscopy were used to identify ICLCs in live tissue. Methylene blue stained cells with morphology suggestive of ICLCs in the TD. Immunoreactivity localized the ICLC protein markers c-kit, CD34 and vimentin to many cells and processes associated with smooth muscle cells (SMCs): coexpression of c-kit with vimentin or CD34 was observed in some cells. Electron microscopy analysis confirmed ICLCs as a major cell type of the human TD. Lymphatic ICLCs possess caveolae, dense bands, a patchy basal lamina, intermediate filaments and specific junctions to SMCs. ICLCs were ultrastructurally differentiable from other interstitial cells observed: fibroblasts, mast cells, macrophages and pericytes. Lymphatic ICLCs were localized to the subendothelial region of the wall as well as in intimate association with smooth muscle bundles throughout the media. ICLCs were morphologically distinct with multiple processes and also spindle shapes. Confocal imaging with calcium-dependent fluorophores corroborated cell morphology and localization observed in fixed tissues. Lymphatic ICLCs thus constitute a significant cell type of the human TD and physically interact with lymphatic SMCs. Copyright © 2012 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the presence of interstitial Cajal-like cells (ICLCs) in the human gallbladder and to determine their distinctive characteristics on the basis of double immunohistochemical staining. Gallbladder specimens were obtained from 30 patients subjected to elective laparoscopic cholecystectomy for symptomatic gallstone disease. Tissue samples were fixed in 4% phosphate-buffered paraformaldehyde, processed, embedded in paraffin, and, after sectioning, routinely stained with HE. Tissue antigens were retrieved using the heat-induced epitope retrieval (HIER) method. For simultaneous visualisation of two antigens, an indirect double immunofluorescence procedure was applied. ICLCs were defined as CD117-immunopositive and tryptase-immunonegative objects. They were predominantly fusiform in shape with sparse branches that were visible in some sections. ICLCs were observed throughout the organ including the gallbladder's fundus, body (corpus) and neck, being most numerous in the corpus. The ICLCs were detected almost exclusively within the muscularis propria and they were arranged parallel to smooth muscle cells. The following subpopulations of ICLCs were observed: ICLC-IM (intramuscular ICLCs) localised between smooth muscle fibres forming one muscle bundle; and ICLC-IB (interbundle ICLCs) localised within the connective tissue separating smooth muscle bundles. Thus, the presence of ICLCs in the human gallbladder was clearly identified, demonstrated by double immunohistochemistry which was found to be a reliable method for differentiating ICLCs from mast cells. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: The presence of c-kit positive neurons in sensory ganglia has been verified in various species but not in humans. Our aim has been to identify whether human primary trigeminal neurons label with c-kit/CD117 and thus, whether data gathered in animal studies can be extrapolated to humans. We also intended to establish whether, and which non-neuronal cells also label with c-kit in the trigeminal ganglion. Methods: Human adult trigeminal ganglia from eight cadavers were processed for immunohistochemistry on paraffin embedded samples using monoclonal antibodies for CD117/c-kit, and three additional trigeminal ganglia were used for transmission electron microscopy (TEM). To evaluate which neuronal type (A or B) was labeled with c-kit, we evaluated the same neurons on adjacent sections labeled with antibodies for neurofilaments (NF). Results: c-kit has labeled trigeminal neurons (TNs), mast cells and interstitial cells (ICs) within the trigeminal ganglion. c-kit+TNs were NF–and thus were strongly presumed to be nociceptive, as such neurons are known to be NF-poor. c-kit+ICs with long and moniliform processes intermingled with the satellite glial cells (SGCs) of the neuronal envelopes. TEM evaluations confirmed this mixed composition of the neuronal envelopes and demonstrated that the perineuronal ICs are in fact interstitial Cajal-like cells (ICLCs) and/or telocytes. Conclusions: c-kit+TNs were objectified in humans and strongly presumed to be nociceptive. TNs envelopes mostly consist of SGCs, but are also combined with ICLCs/telocytes. [Copyright &y& Elsevier]

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. Copyright © 2010 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Cells of the female reproductive tract are subject to hormonal control via sex steroid genomic receptors expressed at nuclear level. We previously showed that interstitial Cajal-like cells (ICLC) of human myometrium expressed estrogen and progesterone receptors (ER/PR). Our aim, based on these results, was to see if ER and/or PR could be found also in tubal ICLC. Indeed, we present here immunohistochemical evidence that ICLC of human Fallopian tube (isthmic region) have such receptors. Stromal ICLC, as well as ICLC among smooth muscle layers, were identified in tissue sections by their morphological features (e.g. several very long, moniliform, prolongations of cell body) as well as by c-kit positivity, vital staining with methylene blue or silver impregnation. Additional evidence was provided by sequential staining for c-kit and for PR on the same cell, by ‘sandwich method’. In vitro, the 4th passage cell cultures from Fallopian tube muscularis exhibiting ICLC morphology showed the presence of ER-alpha and/or PR-A by immunofluorescence. In conclusion, our data suggest that ICLC could function as steroid sensors, and might be implicated in Fallopian tube motility (via gap junctions or juxta- and/or paracrine mechanisms). [ABSTRACT FROM AUTHOR]

Recent studies suggested that various cell lineages exist within the subepicardium and we supposed that this area could host cardiac stem cell niches (CSCNs). Using transmission electron microscopy, we have found at least 10 types of cells coexisting in the subepicardium of normal adult mice: adipocytes, fibroblasts, Schwann cells and nerve fibres, isolated smooth muscle cells, mast cells, macrophages, lymphocytes, interstitial Cajal-like cells (ICLCs) and cardiomyocytes progenitors (CMPs). The latter cells, sited in the area of origin of coronary arteries and aorta, showed typical features of either very immature or developing cardiomyocytes. Some of these cells were connected to each other to form columns surrounded by a basal lamina and embedded in a cellular network made by ICLCs. Complex intercellular communication occurs between the ICLCs and CMPs through electron-dense nanostructures or through shed vesicles. We provide here for the first time the ultrastructural description of CSCN in the adult mice myocardium, mainly containing ICLCs and CMPs. The existence of resident CMPs in different developmental stages proves that cardiac renewing is a continuous process. We suggest that ICLCs might act as supporting nurse cells of the cardiac niches and may be responsible for activation, commitment and migration of the stem cells out of the niches. Briefly, not only resident cardiac stem cells but also ICLCs regulate myocyte turnover and contribute to both cardiac cellular homeostasis and endogenous repair/remodelling after injuries. [ABSTRACT FROM AUTHOR]

During the last few years, there is an increasing interest in the role of the epicardium in cardiac development, myocardial remodelling or repair and regeneration. Several types of cells were described in the subepicardial loose connective tissue, beneath the epicardial mesothelium. We showed previously (repeatedly) the existence of interstitial Cajal-like cells (ICLCs) in human and mammalian myocardium, either in atria or in ventricles. Here, we describe ICLCs in adult mice epicardium and primary culture as well as in situ using frozen sections. The identification of ICLCs was based on phase contrast microscopy and immunophenotyping. We found cells with characteristic morphologic aspects: spindle-shaped, triangular or polygonal cell body and typical very long (tens to hundreds micrometres) and very thin cytoplasmic processes, with a distinctive 'beads-on-a-string' appearance. The dilations contain mitochondria, as demonstrated by MitoTracker Green FM labelling of living cells. Epicardial ICLCs were found positive for c-kit/CD117 and/or CD34. However, we also observed ICLCs positive for c-kit and vimentin. In conclusion, ICLCs represent a distinct cell type in the subendocardium, presumably comprising at least two subpopulations: (i ) c-kit/CD34-positive and (ii ) only c-kit-positive. ICLCs might be essential as progenitor (or promoter) cells for developing cardiomyocyte lineages in normal and/or injured heart. [ABSTRACT FROM AUTHOR]

Summary: It has been suggested that interstitial Cajal-like cells (ICLC) may be involved in the spontaneous rhythmic electrical activities of the extrahepatic bile duct system. The present study investigated the distribution and characteristics of ICLC, which are immunopositive for CD117/ Kit receptor tyrosine kinase, using immunohistochemistry employing a monoclonal antibody raised against CD117/Kit on whole-mount preparations. The Kit-positive ICLC were examined using confocal laser scanning microscopy or fluorescence microscopy. ICLC, immunoreactive for Kit, were pleiomorphic and/or spindle-shaped cells with a few bipolar processes and distributed in the smooth muscle layers of the gallbladder and bile duct system. They were scattered in the hepatic duct, cystic duct and gallbladder as well as in the upper part of the common bile duct. The ICLC gradually increased in number and formed a completed cellular network in the lower part of the common bile duct and ampulla. The numbers of ICLC in the ampulla were similar to that of the duodenum and significantly much greater in number than in the gallbladder and bile ducts. The density of the ICLC in the common bile duct was significantly higher than that of other bile ducts. Our results suggested that the ICLC might contribute to the regulation of the spontaneous rhythmic contraction and development of motility disorders of the bile duct system. [Copyright &y& Elsevier]

CD117 (or c-kit) is expressed by the interstitial cells of Cajal (ICC), which are located within the gastrointestinal (GI) muscle coat and directly involved in its motility. CD34 is expressed by several cell types some of which have features and location resembling the ICC; however, a sure identification of these cells is still lacking. In order to establish whether the CD34-positive cells of the human GI tract are to be considered as ICC subpopulation or a novel independent cell type, and to hypothesize their nature and role, we verified CD34 and CD117 receptor expression under light and fluorescence microscope and performed a routine and a CD34-immuno-electron microscopy. CD34-positive cells were seen in the entire human GI tract. In the muscularis propria, shared morphologies similar to the c-kit-positive cells, in the submucosa, resembled fibroblasts. Their ultrastructure resembled that of the fibrocytes/fibroblasts and of the interstitial Cajal-like cells (ICLC). Double labelling and immunoelectro-microscopy demonstrated that they are unequivocally different to the ICC and, due to the similarities with the ICLC, we identified them as ICLC. The novelty of these results is that two types of interstitial cells are present in the GI muscle coat of humans: the ICC and the ICLC. We hypothesize a mechanical role for the septal ICLC, those at the myenteric plexus level and those bordering the muscle layers; a helping role in neurotransmission is proposed for the ICLC intercalated with the intramuscular ICC, possibly in spreading the slow waves generated by the ICC. Furthermore, the possibility that the ICLC represent the adult mesenchymal stromal cells able to guarantee the ICC renewal deserves to be considered. [ABSTRACT FROM AUTHOR]

We present here evidence for the existence of a new type of interstitial cell in human myocardial sleeves of pulmonary veins: interstitial Cajal-like cell (ICLC). This cell fulfils the criteria for positive diagnosis of ICLC, including CD 117/c-kit positivity. Transmission electron microscopy revealed typical ICLC with 2 or 3 very long processes (several tens of mm) suddenly emerging from the cellular body. Also, these processes appear moniliform but extremely thin (0.1-0.4 mm) under the resolving power of the usual microscopy. Cell processes establish close spatial relationships between each other, as well as with capillaries and nerve endings. ICLC appear located among the myocardial cells and particularly at the border between the myocardial sleeve and pulmonary vein wall. [ABSTRACT FROM AUTHOR]

Intercalated discs (ID) are complex junctional units that connect cardiac myocytes mechanically and electrochemically. However, there is limited information concerning the cardiomyocyte interaction with interstitial non-muscle cells. Our previous studies showed that myocardial interstitial Cajal-like cells (ICLC) are located in between cardiomyocytes, blood capillaries and nerve fibres. Typically, ICLC have several very long, moniliform, cytoplasmic processes which establish closed contacts with nerve fibres, as well as each other. We report here ultrastructural evidence concerning the relationships of ICLC processes with ID. The ICLC cytoplasmic prolongations (tens micrometers length) preferentially pass by or stop nearby the ID. Transmission electron microscopy emphasized three distinct connecting features between the tips of ICLC extensions and myocytes at the 'mouth' of ID: free or budding shed vesicles, exocytotic multi-vesicular bodies and direct contacts. In the last case, electron-dense repetitive nanostructures ('pillars') (35-40 nm high and 100-150 nm wide, similar to adhesion molecules) fasten the ICLC to the myocytes. All these features suggest a juxtacrine and/or paracrine intercellular mutual modulation of ICLC and cardiomyocytes in the microenvironment of ID, possibly monitoring the cardiac functions, particularly the electrical activity. [ABSTRACT FROM AUTHOR]

Recently, parallels have been drawn between enteric interstitial cells of Cajal (ICC) and similar cells outside the gut—interstitial Cajal-like cells (ICLC). This article reviews our laboratory findings on ICLC in the female reproductive tract. Since the morphology and function of ICLC are still a subject of debate, our purpose was to investigate whether ICLC are present in the fallopian tube and/or uterus, and if they share ultrastructural and immunohistochemical (IHC) features and/or functional roles. We studied ICLC presence in the human fallopian tube and myometrium primarily by light microscopy, and then by transmission electron microscopy (TEM), in tissue samples and at a single cell level. Taking advantage of our ICLC studies of several organs (pancreas, mammary gland, myocardium), we assembled a set of criteria, derived from ultrastructural features of ICLC, called “platinum standard.” Besides the putative pacemaker function, ICLC might have other physiological roles, depending on tissue type (e.g., intercellular signaling, immune surveillance, steroid sensors). Consequently, there is a great urge for a conceptual framework that could allow a better understanding, from a functional point of view, and more so, as the ICLC processes are the longest cellular prolongations (except neurons). [ABSTRACT FROM AUTHOR]

Cholesterol gallstone (CG) is a common, frequent biliary system disease in China, with a complex and multifactorial etiology. Declined gallbladder motility reportedly contributes to CG pathogenesis. Furthermore, interstitial Cajal-like cells (ICLCs) are reportedly present in human and guinea pig gallbladder tissue. ICLCs potentially contribute to the regulation of gallbladder motility, and aberrant conditions involving the loss of ICLCs and/or a reduction in its pacing potential and reactivity to cholecystokinin may promote CG pathogenesis. This review discusses the association between ICLCs and CG pathogenesis and provides a basis for further studies on the functions of ICLCs and the etiologies of CG., Competing Interests: Conflict-of-interest statement: The authors have no conflicts of interest to disclose., (©The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved.)

Introduction: A reduced number of interstitial Cajal-like cells (ICLCs) in the gallbladder have been proposed to play a role in the pathogenesis of cholelithiasis. Therefore, this prospective study was conducted to investigate the relationship between gallbladder contractility and the number of gallbladder ICLCs in patients with cholelithiasis., Material and Methods: Patients admitted to the Department of Hepatobiliary Surgery for cholecystectomy were divided into the cholelithiasis (n = 18) and non-cholelithiasis (n = 8) groups based on their clinical data. Patients' clinical data were collected on admission, and B-mode ultrasonography was performed to assess their gallbladder contractility. The resected gallbladder specimens were fixed, paraffin sections mounted on slides, and the immunofluorescence staining with the anti-human CD-117 and anti-human tryptase antibodies was performed to identify ICLSs and mast cells, respectively. The number of ICLCs was counted in 10 high-power fields (HPFs) randomly., Results: Independent sample t-tests revealed differences between the cholelithiasis and non-cholelithiasis groups in the number of ICLCs (mean ± standard deviation: 88.61 ± 28.22 vs. 115.89 ± 27.87 per HPFs, P = 0.032) and gallbladder contractility (43.94% ± 18.50% vs. 61.00% ± 20.50%, P = 0.046). Pearson and Spearman cor-relation analyses revealed no significant correlation between the number of ICLCs and gallbladder contractility., Conclusion: The results suggest that the number of gallbladder ICLCs in the wall of the gallbladder of patients with or without cholelithiasis is not a decisive factor affecting gallbladder contractility.