Shifting into high gear: how interstitial cells of Cajal change the motility pattern of the developing intestine.

The first contractile waves in the developing embryonic gut are purely myogenic; they only involve smooth muscle. Here, we provide evidence for a transition from smooth muscle to interstitial cell of Cajal (ICC)-driven contractile waves in the developing chicken gut. In situ hybridization staining for anoctamin-1 (ANO1), a known ICC marker, shows that ICCs are already present throughout the gut, as from embryonic day (E)7. We devised a protocol to reveal ICC oscillatory and propagative calcium activity in embryonic gut whole mount and found that the first steady calcium oscillations in ICCs occur on (E14). We show that the activation of ICCs leads to an increase in contractile wave frequency, regularity, directionality, and velocity between E12 and E14. We finally demonstrate that application of the c-KIT antagonist imatinib mesylate in organ culture specifically depletes the ICC network and inhibits the transition to a regular rhythmic wave pattern. We compare our findings to existing results in the mouse and predict that a similar transition should take place in the human fetus between 12 and 14 wk of development. Together, our results point to an abrupt physiological transition from smooth muscle mesenchyme self-initiating waves to ICC-driven motility in the fetus and clarify the contribution of ICCs to the contractile wave pattern.NEW & NOTEWORTHY We reveal a sharp transition from smooth muscle to interstitial cell of Cajal (ICC)-driven motility in the chicken embryo, leading to higher-frequency, more rhythmic contractile waves. We predict the transition to happen between 12 and 14 embryonic wk in humans. We image for the first time the onset of ICC activity in an embryonic gut by calcium imaging. We show the first KIT and anoctamin-1 (ANO1) in situ hybridization micrographs in the embryonic chicken gut.

[Gastrointestinal leiomyoma with interstitial cells of Cajal: mimicker of gastrointestinal stromal tumor].

Objective: To study clinical and pathologic characteristics of leiomyomas of the gastrointestinal tract, and to investigate the distribution characteristics of interstitial cells of Cajal ( ICCs ) in gastrointestinal leiomyomas. Methods: One hundred and forty-seven cases of leiomyomas of gastrointestinal tract were collected at the Second Affiliated Hospital of Zhengzhou University from June 2012 to June 2017. Clinical and pathologic findings were analyzed, combined with immunohistochemistry, Alcian blue-osafranin staining and molecular study. Results: The age of patients ranged from 13-82 years with mean age of 52 years. Male to female ratio was about 1∶2. Histologically, all tumors were composed of ovoid to spindle cells arranged in short intersecting fascicles. All tumors were diffusely and strongly positive for smooth muscle antibodies, desmin and h-caldesmon by immunohistochemical staining. A prominent interspersed subpopulation of elongated/dendritic-like cells with CD117 and DOG1 positivity (accounting for 1% to 30% of all tumor cells) and negative for Alcian blue-osafranin staining was identified in all esophageal leiomyomas, 16 of 20 (80%) gastric leiomyomas and 3 of 12 small bowel leiomyomas, but none in colonic/rectal leiomyomas. Mutational analysis in 16 cases showed absence of mutation in exons 9, 11, 13 or 17 of C-KIT and exons 12 or 18 of PDGFRA. Conclusions: ICCs are identified in esophageal and gastric leiomyomas, as well as in small percentage of intestinal leiomyomas. Such findings may bring significant diagnostic pitfalls for misdiagnosis as gastrointestinal stromal tumor. Careful attention to the distribution of CD117 and DOG1 positive cells and molecular mutation analysis of C-KIT and PDGFRA may be necessary to establish the correct diagnosis.

Experience-Dependent Regulation of Cajal-Retzius Cell Networks in the Developing and Adult Mouse Hippocampus.

In contrast to their near-disappearance in the adult neocortex, Cajal-Retzius cells have been suggested to persist longer in the hippocampus. A distinctive feature of the mature hippocampus, not maintained by other cortical areas, is its ability to sustain adult neurogenesis. Here, we have investigated whether environmental manipulations affecting hippocampal postnatal neurogenesis have a parallel impact on Cajal-Retzius cells. We used multiple mouse reporter lines to unequivocally identify Cajal-Retzius cells and quantify their densities during postnatal development. We found that exposure to an enriched environment increased the persistence of Cajal-Retzius cells in the hippocampus, but not in adjacent cortical regions. We did not observe a similar effect for parvalbumin-expressing interneurons, which suggested the occurrence of a cell type-specific process. In addition, we did not detect obvious changes either in Cajal-Retzius cell electrophysiological or morphological features, when compared with what previously reported in animals not exposed to enriched conditions. However, optogenetically triggered synaptic output of Cajal-Retzius cells onto local interneurons was enhanced, consistent with our observation of higher Cajal-Retzius cell densities. In conclusion, our data reveal a novel form of hippocampal, cell type-specific, experience-dependent network plasticity. We propose that this phenomenon may be involved in the regulation of enrichment-dependent enhanced hippocampal postnatal neurogenesis.

Superficial leiomyomas of the gastrointestinal tract with interstitial cells of Cajal.

OBJECTIVE: Some authors suggest common origin of gastrointestinal stromal tumors from stem cells, which may show diverse differentiation. There are reports in which cells morphologically identical to the interstitial cells of Cajal are found in deep leiomyomas. The aim of this study was to demonstrate CD117 positive cells in superficial gastrointestinal (GI) leiomyomas and to find other cells that would suggest diverse differentiation in histologically typical leiomyoma. MATERIALS AND METHODS: We analyzed 8 cases of superficial leiomyomas and one deep leiomyoma, received in our institutions as endoscopically or surgically obtained material. The tumor sections were immunohistochemicaly stained with CD117, CD34, NF, S100, αSMA, desmin, caldesmon and mast cell antigen. RESULTS: All leiomyomas showed diffuse positivity for αSMA, caldesmon and desmin. All of them had CD117 and CD34 positive cells morphologically identical to the interstitial cells of Cajal between smooth muscle fibers, 5 had S-100 and NF positive cells and 2 showed positivity for GFAP. The cells were found in different quantity; they were usually diffusely scattered through the tumors without predilection site, forming small groups in some areas. CONCLUSION: CD177, CD34, S-100 and NF positive cells are present in superficial leiomyomas and they may suggest common origin of GI stromal tumors.

Expression and function of muscarinic subtype receptors in bladder interstitial cells of cajal in rats.

PURPOSE: To locate the muscarinic (M) M2 and M3 receptors in bladder interstitial cells of Cajal (ICCs) and to determine the effects of M2 and M3 agonists on bladder ICCs. MATERIALS AND METHODS: A total of 30 adult male Sprague-Dawley rats weighing 225-250 g were used in this study. Double-labeled fluorescence of muscarinic receptors and c-kit was performed for co-localization. To evaluate the effect of muscarinic agents on the excitation of bladder ICCs, we analyzed the inward current of bladder ICCs using the whole-cell patch clamp. The effect of muscarinic agents on the carbachol-induced inward currents was evaluated with the whole-cell patch clamp. RESULTS: M2 and M3 receptors were confirmed in the stroma ICCs in rats' bladders with double-labeled immunofluorescence. Spontaneous action potential was observed in freshly isolated bladder ICCs. The carbachol-induced inward Ca2+ current in ICCs can be blocked by atropine. The M2 receptor antagonist methoctramine (1 µM) showed a weak inhibitory capability on the inward Ca2+ current [from 74.8 ± 9.6 to 63.3 ± 13.8 Pascal (pA), n = 12, P = .03]. While the M3 receptor antagonist 4-diphenyl-acetoxy-N-methyl-piperidine methiodide (4-DAMP) (1 µM) significantly inhibited the inward Ca2+ current (from 78.4 ± 11.2 to 17.3 ± 7.9 pA, n = 12, P < .001). CONCLUSION: Bladder ICCs express M2 and M3 cholinergic receptors. Most muscarinic cholinergic receptor antagonists, especially the M3 antagonists, can effectively inhibit the carbamylcholine- induced inward current of bladder ICCs.

Calcium responses in subserosal interstitial cells of the guinea-pig proximal colon.

BACKGROUND: In the subserosal layer between the longitudinal muscle layer and mesothelium, heterogeneous populations of interstitial cells are distributed. As the distribution of nerve elements in this layer is sparse as compared with the nerve plexus layer or tunica muscularis, there may be unique communication among subserosal interstitial cells (SSICs). This study aimed to explore functional properties of SSICs. METHODS: In subserosal preparations of the guinea-pig proximal colon, changes in intracellular Ca(2+) ([Ca(2+) ]i ) were visualized using Fluo-4 Ca(2+) imaging. Immunohistochemistry was also performed to identify the SSICs exhibiting Ca(2+) transients. KEY RESULTS: A majority of SSICs responded to adenosine triphosphate (ATP, 10 µM) by increasing [Ca(2+) ]i , but remained quiescent during the application of acetylcholine (10 µM). ATP-induced Ca(2+) responses were mimicked by adenosine 5'-diphosphate (10 µM), MRS2365 (10 nM) but not α, ß-methylene ATP (10 µM) or uridine triphosphate (10 µM), and could be reproduced in Ca(2+) -free solution, suggesting that ATP acts via P2Y receptors, most likely P2Y1 subtype, but not P2X receptors. Live staining of the same preparations after Ca(2+) imaging indicated the ATP-sensitive SSICs were not positive for c-Kit antibody, a specific marker for gastrointestinal interstitial cells of Cajal (ICC). Immunohistochemistry identified vimentin (mesenchymal cell marker)+/Kit- and SK3 (fibroblast-like cell (FLC) marker)+/Kit- cells that had a similar morphology to the ATP-sensitive SSICs in Ca(2+) imaging. CONCLUSIONS & INFERENCES: A majority of the SSICs in the guinea-pig proximal colon, presumably FLC, are capable of responding to ATP and thus may contribute to smooth muscle relaxation upon stimulation with ATP released from non-neuronal cells.

Leiomyoma of the gastrointestinal tract with interstitial cells of Cajal: a mimic of gastrointestinal stromal tumor.

Leiomyomas (LMs) of the gastrointestinal tract arise within the muscularis mucosae (superficial) and muscularis propria (deep). There are isolated reports of KIT-positive cells, presumed interstitial cells of Cajal (ICCs), within gastrointestinal LMs. We have encountered esophageal LMs with a high proportion of KIT-positive and DOG1-positive spindle-shaped cells, an appearance that mimicked gastrointestinal stromal tumor. Our aim was to explore the prevalence of ICCs in LMs of the gastrointestinal tract and the etiopathogenic significance of these cells in this benign neoplasm. We identified 34 esophageal LMs (28 deep, 6 superficial), 8 gastric LMs, and 5 small-bowel LMs (all lesions in muscularis propria). We performed immunohistochemical staining studies for desmin, DOG1, and KIT on these neoplasms. We also evaluated 12 superficial colonic LMs. ICCs were distinguished from mast cells on the basis of morphology (elongated and occasionally branching spindle-shaped cells) and the presence of DOG1 reactivity. Four cases were screened for mutations in PDGFRA exons 12, 14, and 18 and KIT exons 9, 11, 13, and 17. ICCs were identified in all deep esophageal LMs and constituted an average of 20% of the lesional cells; focally, these cells comprised >50% of cells. The density of these cells was significantly higher than the background muscularis propria, and hyperplasia of ICCs was not identified in the adjacent muscle. ICCs were identified in 6 of 8 gastric LMs and 1 of 5 small-bowel LMs and were entirely absent in all superficial esophageal and colonic/rectal LMs. There were no mutations in KIT or PDGFRA. ICCs are universally present in deep esophageal LMs, and thus these neoplasms could be mistaken for gastrointestinal stromal tumors, particularly on biopsy samples, an error associated with adverse clinical consequences. ICCs are also identified in gastric and intestinal LMs, albeit in a smaller proportion of cases. Colonization and hyperplasia by non-neoplastic ICCs likely account for this phenomenon.

Long segmental hyperplasia of interstitial cells of Cajal with giant diverticulum formation.

Sporadic gastrointestinal stromal tumors (GISTs) usually form a well-circumscribed mass. In contrast, diffuse interstitial cell of Cajal (ICC) hyperplasia along the Auerbach plexus without a discrete mass may occur in patients with germline mutations in the NF1, c-KIT or PDGFRA genes. However, sporadic, diffuse ICC hyperplasia without c-KIT or PDGFRA mutations has not been reported. We describe herein one such case, forming a giant diverticulum. A 63-year-old woman with no features of Neurofibromatosis 1 (NF1) presented with increasing abdominal pain for more than 30 years. A large, diverticulum-like mass in the ileum was resected. Microscopically, a diffuse proliferation of bland spindle cells was seen extending for 12 cm, replacing the muscularis propria and lined by intact mucosa. The spindle cells were CD117+/CD34+/DOG1+/SMA+/Desmin-/S100-. Mutation analyses did not reveal any mutations in c-KIT or PDGFRA. The lesion had two silent mutations in the NF1 gene. It is rare of the diffuse form of sporadic ICC hyperplasia showing diffuse longitudinal microscopic growth completely replacing the muscularis propria, mimicking diffuse ICC hyperplasia in hereditary GIST syndromes, but without solid components and no c-KIT or PDGFRA gene mutations. This peculiar form of sporadic ICC hyperplasia may be related to intestinal dysmotility in this ileal segment and giant diverticulum formation.

Interstitial cells of Cajal: crucial for the development of megacolon in human Chagas' disease?

AIM: Megacolon, chronic dilation of a colonic segment,is accompanied by extensive myenteric neuron loss. However, this fails to explain unequivocally the formation of megacolon. We aimed to study further enteric structures that are directly or indirectly involved in colonic motility. METHOD: From surgically removed megacolon segments of seven Chagasic patients, three sets of cryosections from oral, megacolonic and anal zones were immunohistochemically quadruple-stained for smooth-muscle actin (SMA), synaptophysin (SYN, for nerve fibres), S100 (glia) and c-Kit (interstitial cells of Cajal, ICCs). Values of area measurements were related to the appropriate muscle layer areas and these proportions were compared with those of seven non-Chagasic control patients. RESULTS: Whereas nerve and glia profile proportions did not mirror unequivocally the changes of Chagasic colon calibre (nondilation/dilation/nondilation), the proportions of SMA (i.e. muscle tissue density) and c-Kit (i.e. ICC density) did so: they decreased from the oral to the megacolonic segment but increased to the anal zones (muscle tissue density: control 68.3%, oral 54.3%, mega 42.1%, anal 47.6%; ICC-density: control 1.8%, oral 1.1%, mega 0.4, anal 0.8%). CONCLUSION: Of the parameters evaluated, muscle tissue and ICC densities may be involved in the formation of Chagasic megacolon, although the mechanism of destruction cannot be deduced.

Pancreatic extragastrointestinal stromal tumors, interstitial Cajal like cells, and telocytes.

CONTEXT: The discovery and subsequent ultrastructural characterization of the interstitial Cajal like cells (now called telocytes) in virtually every anatomic sites of the human body, by Laurentiu M Popescu and co-workers, have dramatically improved the understanding the function of these cells and pathogenesis of extragastrointestinal stromal tumors (EGIST). Pancreatic extragastrointestinal stromal tumors (pEGIST), phenotypically similar to pancreatic interstitial Cajal like cells, are extremely rare with an unpredictable biological behavior. OBJECTIVE: To review the clinicopathological, radiological, immunohistochemical, and therapeutic outcome data of all reported cases of pEGIST, and highlight the developments in the field of pancreatic interstitial Cajal like cells/telocytes. METHODS: A systematic review of English literature (January 2000 to July 2012) was done by using the search engine of PubMed, PubMed Central, Google Scholar, and the Directory of Open Access Journals. RESULTS: There have been 19 reported cases of pEGIST during the last decade, over an age range of 31 to 84 years (mean: 56 years) with equal gender predilection ((male:female ratio: 9:10). Preoperative radiological characteristics have been mostly nondiagnostic though these were used, in some, for tissue diagnosis. Majority of pEGIST were localized to pancreatic head (8/19, 42.1%), and 15 of 19 patients (78.9%) were symptomatic at first presentation. The mean size ranged from 2.5 to 35cm (mean: 14 cm). Histomorphological features were that of predominantly spindle cell tumor which consistently expressed c-KIT/CD117 and CD34 by immunohistochemistry, making these two as the most sensitive markers at this site. RESULTS: from studies involving discovery on gastrointestinal stromal tumor 1 (DOG-1), the most specific biomarker of GIST/EGIST, has been inconclusive and this was found to be positive in one case only. Neoadjuvant chemotherapy with imatinib mesylate and sunitinib were used in few cases, and genetic analysis of c-KIT proto-oncogene was done in two. By univariate analysis, none of the clinicopathological parameters, except surgical resection with microscopic free margin (R0 resection) (P<0.05), were found to be an important indicators of outcome. CONCLUSION: The biological behavior of pEGIST, at present, seems unpredictable which requires indefinite period of follow-up. Large number of such cases with genetic analysis supplemented with immunohistochemistry studies will hopefully throw more light in these tumors.

The distribution of HCN2-positive cells in the gastrointestinal tract of mice.

HCN2 channels are involved in the spontaneous rhythmic activities of some CNS neurons and act by generating I(f) current. The gastrointestinal (GI) tract is known to be capable of spontaneous rhythmic activity; however, the possible role of HCN2 channels in this organ has not yet been elucidated. This study investigated the distribution of HCN2-positive cells in the mouse GI tract using immunohistochemistry. To identify the nature of these HCN2 cells, anti-ChAT and anti-Kit antibodies were used to co-label neurons and the interstitial cells of Cajal (ICCs), respectively. Additionally, differences in the distribution of HCN2-positive cells within the GI tract were also analyzed. Our results showed that HCN2 channels were mainly located within the myenteric neurons of the enteric nervous system in the GI tract. Double-staining revealed that HCN2-positive neurons were labeled by ChAT, indicating that these HCN2-positive cells are also cholinergic neurons. Although the HCN2-positive cells were not stained by the anti-Kit antibody, their processes were in close proximity to ICCs around the myenteric plexus region. Moreover, several differences in the distribution of HCN2 in the stomach, small intestine and colon were partly consistent with the regional differences in the spontaneous rhythmic activities of these organs. Basing on the role HCN2, we suggested that HCN2 channels facilitate the release of Ach from cholinergic neurons to affect the GI peristalsis by acting on M receptors on the ICCs. However, the HCN2 channels are not directly involved in spontaneous slow-wave initiation by ICCs.

[Effect of electroacupuncture at "Tianshu"(ST 25) on colonic smooth muscle structure and interstitial cells of cajal in slow transit constipation rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) of "Tianshu" (ST 25) on colonic smooth muscle structure and interstitial cells of Cajal (ICC) in slow transit constipation (STC) rats, so as to investigate its mechanism underlying improving STC. METHODS: Wistar rats (n = 56) were randomly allocated to control (n = 20), model and EA groups (n = 18/ group). STC model was established by feeding the rats with forage containing compound Diphenoxylate. EA (0.8 - 1.3 mA, 2 Hz/15 Hz) was applied to bilateral "Tianshu" (ST 25) for 15 min, once daily for 14 days. The treatment was given beginning from the next day on after the rat's first black stool excretion was found. The colonic smooth muscle structure was observed under microscope after sectioning and HE staining. The immunoactivity (average optical density, OD) of intestinal immuno-reaction (IR) po-sitive ICC product was detected by immunohistochemistry. RESULTS: (1) Microscopic observation displayed that after modeling, the rat's intestinal mucosa gland showed atrophy with reduction in the acinar number, being sparse in distribution; and the smooth muscle thickness was obviously thinner compared with the normal control group (P < 0.05). Whereas this situation of the colonic smooth muscle in the EA group was close to that of the normal control group. Compared with the model group, the thickness of the intestinal smooth muscle in the EA group was significantly bigger (P < 0.05). (2) Immunohistochemical results showed that the average OD values and number of IR-positive colonic ICC in the model group were obviously decreased in comparison with the normal control group (P < 0.05). Compared with the model group, the average OD values and the number of IR-positive coIonic ICC in the EA group were upregulated considerably (P < 0.05). CONCLUSION: EA of bilateral "Tianshu"(ST 25) is able to improve STC-induced structural changes of the colonic smooth muscle, and upregulate expression of colonic ICC in STC rats, which may be responsible for its efficacy in improving STC.

Extrahepatic and intrahepatic human portal interstitial Cajal cells.

Portal interstitial cells of Cajal (PICCs), acting as vascular pacemakers, were previously only identified in nonhumans. Moreover, there is no evidence available about the presence of such cells within the liver. The objective of the study is to evaluate whether or not PICCs are identifiable in humans and, if they are, whether or not they are following the scaffold of portal vein (PV) branches within the liver. We obtained extrahepatic PVs and liver samples from six adult human cadavers, negative for liver disease, in accordance with ethical rules. They were stained with hematoxylin-eosin (HE) and Giemsa, and then we performed immunohistochemistry on formalin-fixed paraffin-embedded specimens for CD117/c-kit, a marker of the Cajal's cells. Immune labeling was also performed for S-100 protein, desmin, glial fibrillary acidic protein (GFAP), neurofilaments, α-smooth muscle actin (α-SMA), and CD34. c-kit-Positive PICCs were identified within the extrahepatic PV, in portal spaces, and septa. On adjacent sections, these PICCs were negative for all the other antibodies used. In conclusion, our study confirms the presence of extrahepatic PICCs on humans, which may act as a possible intrinsic pacemaker in the human PV. However, the intrahepatic PICCs, which were evidenced here for the first time, are in need for further experimental studies to evaluate their functional role. A promising further direction of the study is the PICCs role in the idiopathic portal hypertension.

Differential changes in intrinsic innervation and interstitial cells of Cajal in small bowel atresia in newborns.

AIM: To investigate morphological changes of the enteric nervous system (ENS) and the interstitial cells of Cajal (ICCs) in small bowel atresia. METHODS: Resected small bowel specimens from affected patients (n = 7) were divided into three parts (proximal, atretic, distal). Standard histology and enzyme immunohistochemistry anti-S100, anti-protein gene product (PGP) 9.5, anti-neurofilament (NF), anti-c-kit-receptor (CD117) was carried out on conventional paraffin sections of the proximal and distal part. RESULTS: The neuronal and glial markers (PGP 9.5, NF, S-100) were expressed in hypertrophied ganglia and nerve fibres within the myenteric and submucosal plexuses. Furthermore, the submucous plexus contained typical giant ganglia. The innervation pattern of the proximal bowel resembled intestinal neuronal dysplasia. The density of myenteric ICCs was clearly reduced in the proximal bowel, whereas a moderate number of muscular ICCs were found. The anti-CD117 immunoreaction revealed additional numerous mast cells. The distal bowel demonstrated normal morphology and density of the ENS, the ICCs and the mast cells. CONCLUSION: The proximal and distal bowel in small bowel atresia revealed clear changes in morphology and density of the ENS and ICCs.

Interstitial cells of Cajal are present in human extrahepatic bile ducts.

BACKGROUND AND AIMS: Interstitial cells of Cajal (ICC) are distributed with smooth muscle throughout the gastrointestinal tract and are involved in regulating motility. ICC were recently discovered in the wall of the human gallbladder. This study sought to determine whether ICC are present in human bile ducts. METHODS: Biliary tract samples were obtained from several sources: surgical specimens (n = 16, 11 women, mean age 61 years); archival post-mortem specimen (n = 1, 86 years, man); and cadavers (n = 2, 68 and 80 years, men). Paraffin-embedded sections (3 microm) from the gallbladder (fundus, body and neck) and both extrahepatic and intrahepatic bile ducts were investigated. A double immunofluorescence protocol using polyclonal and monoclonal c-kit antibodies and mast cell tryptase was used to distinguish c-kit-positive cells with typical ICC morphology from c-kit-positive mast cells. Small bowel samples were used as positive controls. ICC in the gallbladder were confirmed by ultrastructural study. RESULTS: c-kit-positive cells with characteristic ICC morphology were identified in the subepithelial and muscular layers of the gallbladder and extrahepatic bile ducts. They were most prominent within the muscle layer of the extrahepatic bile ducts where they were organized into loosely arranged laminae running parallel to circular smooth muscle fibers. ICC were not found in intrahepatic bile ducts. CONCLUSION: This study demonstrates for the first time that ICC are present in human extrahepatic bile ducts where they are more densely aggregated than in the gallbladder. This cellular network is likely to be involved in biliary tract motility and its related disorders.