Interstitial Cells Of Cajal Networks Research Articles

Perivascular Interstitial Cells of Cajal in Human Colon

Background & AimsInterstitial cells of Cajal (ICC) closely associate with nerves and smooth muscles to modulate gut motility. In the ICC microenvironment, although the circulating hormones/factors have been shown to influence ICC activities, the association between ICC and microvessels in the gut wall has not been described. We applied three-dimensional (3D) vascular histology with c-kit staining to identify the perivascular ICC and characterize their morphologic and population features in the human colon wall.MethodsFull-thickness colons were obtained from colectomies performed for colorectal cancer. We targeted the colon wall away from the tumor site. Confocal microscopy with optical clearing (use of immersion solution to reduce scattering in optical imaging) was performed to simultaneously reveal the ICC and vascular networks in space. 3D image rendering and projection were digitally conducted to illustrate the ICC–vessel contact patterns.ResultsPerivascular ICC were identified in the submucosal border, myenteric plexus, and circular and longitudinal muscles via high-definition 3D microscopy. Through in-depth image projection, we specified two contact patterns—the intimate cell body-to-vessel contact (type I, 18% of ICC in circular muscle) and the long-distance process-to-vessel contact (type II, 16%)—to classify perivascular ICC. Particularly, type I perivascular ICC were detected with elevated c-kit staining levels and were routinely found in clusters, making them readily distinguishable from other ICC in the network.ConclusionsWe propose a new subclass of ICC that closely associates with microvessels in the human colon. Our finding suggests a functional relationship between these mural ICC and microvessels based on the morphologic proximity.

Therapeutic effect and mechanism of electroacupuncture at Zusanli on plasticity of interstitial cells of Cajal: a study of rat ileum.

BackgroundElectroacupuncture (EA) is one of the techniques of acupuncture and is believed to be an effective alternative and complementary treatment in many disorders. The aims of this study were to investigate the effects and mechanisms of EA at acupoint Zusanli (ST36) on the plasticity of interstitial cells of Cajal (ICCs) in partial bowel obstruction.MethodsA Sprague Dawley rat model of partial bowel obstruction was established and EA was conducted at Zusanli (ST36) and Yinglingquan (SP9) in test and control groups, respectively. Experiments were performed to study the effects and mechanisms of EA at Zusanli on intestinal myoelectric activity, distribution and alteration of ICCs, expression of inflammatory mediators, and c-Kit expression.Results1) EA at Zusanli somewhat improved slow wave amplitude and frequency in the partial obstruction rats. 2) EA at Zusanli significantly stimulated the recovery of ICC networks and numbers. 3) the pro-inflammatory mediator TNF-α and NO activity were significantly reduced after EA at Zusanli, However, no significant changes were observed in the anti-inflammatory mediator IL-10 activity. 4) EA at Zusanli re-expressed c-Kit protein. However, EA at the control acupoint, SP9, significantly improved slow wave frequency and amplitude, but had no effect on ICC or inflammatory mediators.ConclusionsWe concluded that EA at Zusanli might have a therapeutic effect on ICC plasticity, and that this effect might be mediated via a decrease in pro-inflammatory mediators and through the c-Kit signaling pathway, but that the relationship between EA at different acupoints and myoelectric activity needs further study.

Developmental changes in postnatal murine intestinal interstitial cell of Cajal network structure and function.

The mammalian gastrointestinal (GI) tract undergoes rapid development during early postnatal life in order to transition from a milk to solid diet. Interstitial cells of Cajal (ICC) are the pacemaker cells that coordinate smooth muscle contractility within the GI tract, and hence we hypothesized that ICC networks undergo significant developmental changes during this early postnatal period. Numerical metrics for quantifying ICC network structural properties were applied on confocal ICC network imaging data obtained from the murine small intestine at various postnatal ages spanning birth to weaning. These imaging data were also coupled to a biophysically-based computational model to simulate pacemaker activity in the networks, to quantify how changes in structure may alter function. The results showed a pruning-like mechanism which occurs during postnatal development, and the temporal course of this phenomenon was defined. There was an initial ICC process overgrowth to optimize network efficiency and increase functional output volume. This was followed by a selective retaining and strengthening of processes, while others were discarded to further elevate functional output volume. Subsequently, new ICC processes were formed and the network was adjusted to its adult morphology. These postnatal ICC network developmental events may be critical in facilitating mature digestive function.

Bone Marrow Derived Kit-positive Cells Colonize the Gut but Fail to Restore Pacemaker Function in Intestines Lacking Interstitial Cells of Cajal.

Background/AimsSeveral motility disorders are associated with disruption of interstitial cells of Cajal (ICC), which provide important functions, such as pacemaker activity, mediation of neural inputs and responses to stretch in the gastrointestinal (GI) tract. Restoration of ICC networks may be therapeutic for GI motor disorders. Recent reports have suggested that Kit+ cells can be restored to the GI tract via bone marrow (BM) transplantation. We tested whether BM derived cells can lead to generation of functional activity in intestines naturally lacking ICC.MethodsBM cells from Kit+/copGFP mice, in which ICC are labeled with a green fluorescent protein, were transplanted into W/WV intestines, lacking ICC. After 12 weeks the presence of ICC was analyzed by immunohistochemistry and functional analysis of electrical behavior and contractile properties.ResultsAfter 12 weeks copGFP+ BM derived cells were found within the myenteric region of intestines from W/WV mice, typically populated by ICC. Kit+ cells failed to develop interconnections typical of ICC in the myenteric plexus. The presence of Kit+ cells was verified with Western analysis. BM cells failed to populate the region of the deep muscular plexus where normal ICC density, associated with the deep muscular plexus, is found in W/WV mice. Engraftment of Kit+-BM cells resulted in the development of unitary potentials in transplanted muscles, but slow wave activity failed to develop. Motility analysis showed that intestinal movements in transplanted animals were abnormal and similar to untransplanted W/WV intestines.ConclusionsBM derived Kit+ cells colonized the gut after BM transplantation, however these cells failed to develop the morphology and function of mature ICC.

Expression and function of a T-type Ca2+ conductance in interstitial cells of Cajal of the murine small intestine

Interstitial cells of Cajal (ICC) generate slow waves in gastrointestinal (GI) muscles. Previous studies have suggested that slow wave generation and propagation depends on a voltage-dependent Ca(2+) entry mechanism with the signature of a T-type Ca(2+) conductance. We studied voltage-dependent inward currents in isolated ICC. ICC displayed two phases of inward current upon depolarization: a low voltage-activated inward current and a high voltage-activated current. The latter was of smaller current density and blocked by nicardipine. Ni(2+) (30 μM) or mibefradil (1 μM) blocked the low voltage-activated current. Replacement of extracellular Ca(2+) with Ba(2+) did not affect the current, suggesting that either charge carrier was equally permeable. Half-activation and half-inactivation occurred at -36 and -59 mV, respectively. Temperature sensitivity of the Ca(2+) current was also characterized. Increasing temperature (20-30°C) augmented peak current from -7 to -19 pA and decreased the activation time from 20.6 to 7.5 ms [temperature coefficient (Q10) = 3.0]. Molecular studies showed expression of Cacna1g (Cav3.1) and Cacna1h (Cav3.2) in ICC. The temperature dependence of slow waves in intact jejunal muscles of wild-type and Cacna1h(-/-) mice was tested. Reducing temperature decreased the upstroke velocity significantly. Upstroke velocity was also reduced in muscles of Cacna1h(-/-) mice, and Ni(2+) or reduced temperature had little effect on these muscles. Our data show that a T-type conductance is expressed and functional in ICC. With previous studies our data suggest that T-type current is required for entrainment of pacemaker activity within ICC and for active propagation of slow waves in ICC networks.

Extensive projections of myenteric serotonergic neurons suggest they comprise the central processing unit in the colon

5-Hydroxytryptamine (5-HT, serotonin) is an important regulator of colonic motility and secretion; yet the role of serotonergic neurons in the colon is controversial. We used immunohistochemical techniques to examine their projections throughout the enteric nervous system and interstitial cells of Cajal (ICC) networks in the murine proximal to mid colon. Serotonergic neurons, which were mainly calbindin positive, occurred only in myenteric ganglia (1 per 3 ganglia). They were larger than nNOS neurons but similar in size to Dogiel Type II (AH) neurons. 5-HT neurons, appeared to make numerous varicose contacts with each other, most nNOS neurons, Dogiel Type II/AH neurons and glial cells. 5-HT, calbindin and nNOS nerve fibers also formed a thin perimuscular nerve plexus that was associated with ganglia, which contained both nNOS positive and negative neurons, which lay directly upon the submucosal pacemaker ICC network. Neurons in perimuscular ganglia were surrounded by 5-HT varicosities. Submucous ganglia contained nNOS positive and negative neurons, and calbindin positive neurons, which also appeared richly supplied by serotonergic nerve varicosities. Serotonergic nerve fibers ran along submucosal arterioles, but not veins. Varicosities of serotonergic nerve fibers were closely associated with pacemaker ICC networks and with intramuscular ICC (ICC-IM). 5-HT2B receptors were found on a subpopulation of non-5-HT containing myenteric neurons and their varicosities, pacemaker ICC-MY and ICC-IM. Myenteric serotonergic neurons, whose axons exhibit considerable divergence, regulate the entire enteric nervous system and are important in coordinating motility with secretion. They are not just interneurons, as regularly assumed, but possibly also motor neurons to ICC and blood vessels, and some may even be sensory neurons.

Mast Cells Play No Role in the Pathogenesis of Postoperative Ileus Induced by Intestinal Manipulation

IntroductionIntestinal manipulation (IM) during abdominal surgery results in intestinal inflammation leading to hypomotility or ileus. Mast cell activation is thought to play a crucial role in the pathophysiology of postoperative ileus (POI). However, this conclusion was mainly drawn using mast cell-deficient mouse models with abnormal Kit signaling. These mice also lack interstitial cells of Cajal (ICC) resulting in aberrant gastrointestinal motility even prior to surgery, compromising their use as model to study POI. To avoid these experimental weaknesses we took advantage of a newly developed knock-in mouse model, Cpa3Cre/+, devoid of mast cells but with intact Kit signaling.DesignThe role of mast cells in the development of POI and intestinal inflammation was evaluated assessing gastrointestinal transit and muscularis externa inflammation after IM in two strains of mice lacking mast cells, i.e. KitW-sh/W-sh and Cpa3Cre/+ mice, and by use of the mast cell stabilizer cromolyn.Results KitW-sh/W-sh mice lack ICC networks and already revealed significantly delayed gastrointestinal transit even before surgery. IM did not further delay intestinal transit, but induced infiltration of myeloperoxidase positive cells, expression of inflammatory cytokines and recruitment of monocytes and neutrophils into the muscularis externa. On the contrary, Cpa3Cre/+ mice have a normal network of ICC and normal gastrointestinal. Surprisingly, IM in Cpa3Cre/+ mice caused delay in gut motility and intestinal inflammation as in wild type littermates mice (Cpa3+/+). Furthermore, treatment with the mast cell inhibitor cromolyn resulted in an inhibition of mast cells without preventing POI.ConclusionsHere, we confirm that IM induced mast cell degranulation. However, our data demonstrate that mast cells are not required for the pathogenesis of POI in mice. Although there might be species differences between mouse and human, our results argue against mast cell inhibitors as a therapeutic approach to shorten POI.

A loss of telocytes accompanies fibrotic remodelling of the colonic wall in ulcerative colitis

Crohn’s disease (CD) and ulcerative colitis (UC) are complex diseases in which the interaction of genetic, environmental and microbial factors drives chronic relapsing and remitting intestinal inflammation that finally leads to extensive tissue fibrosis. In UC, this results in a stiff, fibrotic colon unable to carry out peristalsis or to resorb fluids. Colonic dysmotility is often observed in UC patients and has been linked to severe damages of the enteric neural structures and a reduced density of interstitial cells of Cajal (ICC). Telocytes (TC), a peculiar type of stromal cells, have been recently identified in a variety of human tissues and organs, including the gastrointestinal tract. Several roles have been proposed for TC, including mechanical support, spatial relationships with different cell types, intercellular signalling and modulation of intestinal motility by spreading the slow waves generated by the pacemaker ICC. We have recently demonstrated that a loss of TC accompanies the fibrotic remodelling of the intestinal wall in CD patients. The aim of the present work was to investigate the presence and distribution of TC in colonic specimens from UC patients compared with controls. Archival paraffin-embedded full-thickness samples of the left colon from UC patients who underwent elective bowel resection and controls were collected. Tissue sections were stained with Masson’s trichrome to detect fibrosis. TC were identified by CD34 immunohistochemistry. Double immunofluorescence for CD34 and CD31 (vascular endothelial cells), alpha-SMA (smooth muscle cells, myofibroblasts) and c-kit (ICC) was also performed. In early fibrotic UC cases, fibrosis affected the muscularis mucosae and submucosa, while the muscularis propria was spared. In advanced fibrotic UC cases, fibrosis extended to affect the muscle layers and the myenteric plexus. Few TC were found in the muscularis mucosae and submucosa of both early and advanced fibrotic UC colonic wall. Conversely, numerous myofibroblasts were observed in the submucosa of all UC cases. In the muscle layers and at the myenteric plexus of early fibrotic UC, TC were preserved in their distribution. In the muscularis propria of advanced fibrotic UC, the network of TC was reduced or even completely absent around smooth muscle cells and myenteric plexus ganglia, paralleling the loss of the ICC network. In UC, the loss of TC accompanies the fibrotic remodelling of the colonic wall and might contribute to colonic dysmotility.

Electroacupuncture at ST36 Ameliorates Gastric Emptying and Rescues Networks of Interstitial Cells of Cajal in the Stomach of Diabetic Rats

Depletion of interstitial cells of Cajal (ICC) is certified in the stomach of diabetic patients. Though electroacupuncture (EA) at ST36 is an effective therapy to regulate gastric motility, the mechanisms of EA at ST36 on gastric emptying and networks of ICC remain to be elucidated. The aims of this study were to investigate the effects of EA on gastric emptying and on the alterations of ICC networks. Rats were randomized into the control, diabetic rats (DM), diabetic rats with sham EA (DM+SEA), diabetic rats with low frequency EA (DM+LEA) and diabetic rats with high frequency EA groups (DM+HEA). The expression of c-kit in each layer of gastric wall was assessed by western blotting. The proliferation of ICC was identified by immunolabeling of c-kit and Ki67 as the apoptosis of ICC was examined by TUNEL staining. The results were as follows: (1) Gastric emptying was severely delayed in the DM group, but accelerated in the LEA and HEA group, especially in the LEA group. (2) The expression of c-kit in each layer was reduced apparently in the DM group, but also up-regulated in the LEA and HEA group. (3) Plentiful proliferated ICC (c-kit+/Ki67+) forming bushy networks with c-kit+ cells were observed in the LEA and HEA group, while the apoptotic cells (c-kit+/TUNEL+) were hardly captured in the LEA and HEA group. Collectively, low and high frequency EA at ST36 rescue the damaged networks of ICC by inhibiting the apoptosis and enhancing the proliferation in the stomach of diabetic rats, resulting in an improved gastric emptying.

A Biophysically Based Finite-State Machine Model for Analyzing Gastric Experimental Entrainment and Pacing Recordings

Gastrointestinal motility is coordinated by slow waves (SWs) generated by the interstitial cells of Cajal (ICC). Experimental studies have shown that SWs spontaneously activate at different intrinsic frequencies in isolated tissue, whereas in intact tissues they are entrained to a single frequency. Gastric pacing has been used in an attempt to improve motility in disorders such as gastroparesis by modulating entrainment, but the optimal methods of pacing are currently unknown. Computational models can aid in the interpretation of complex in vivo recordings and help to determine optimal pacing strategies. However, previous computational models of SW entrainment are limited to the intrinsic pacing frequency as the primary determinant of the conduction velocity, and are not able to accurately represent the effects of external stimuli and electrical anisotropies. In this paper, we present a novel computationally efficient method for modeling SW propagation through the ICC network while accounting for conductivity parameters and fiber orientations. The method successfully reproduced experimental recordings of entrainment following gastric transection and the effects of gastric pacing on SW activity. It provides a reliable new tool for investigating gastric electrophysiology in normal and diseased states, and to guide and focus future experimental studies.

Telocytes in Crohn's disease

Crohn’s disease (CD) is a relapsing chronic inflammatory disorder that may involve all the gastrointestinal tract with a prevalence of terminal ileum. Intestinal lesions have a characteristic discontinuous and segmental distribution and may affect all layers of the gut wall. Telocytes (TC), a peculiar type of stromal cells, have been recently identified in a variety of tissues and organs, including gastrointestinal tract of humans and mammals. Several roles have been proposed for TC, including mechanical support, spatial relationships with different cell types, intercellular signalling and modulation of intestinal motility. The aim of our study was to investigate the presence and distribution of TC in disease-affected and -unaffected ileal specimens from CD patients compared with controls. TC were identified by CD34/PDGFRα immunohistochemistry. In affected CD specimens TC disappeared, particularly where fibrosis and architectural derangement of the intestinal wall were observed. In the thickened muscularis mucosae and submucosa, few TC entrapped in the fibrotic extracellular matrix were found. A discontinuous network of TC was present around smooth muscle bundles, ganglia and enteric strands in the altered muscularis propria. At the myenteric plexus, the loss of TC network was paralleled by the loss of interstitial cells of Cajal network. In the unaffected CD specimens, TC were preserved in their distribution. Our results suggest that in CD the loss of TC might have important pathophysiological implications contributing to the architectural derangement of the intestinal wall and gut dysmotility. Further functional studies are necessary to better clarify the role of TC loss in CD pathophysiology.

Are Interstitial Cells of Cajal Involved in Mechanical Stress-Induced Gene Expression and Impairment of Smooth Muscle Contractility in Bowel Obstruction?

Background and AimsThe network of interstitial cells of Cajal (ICC) is altered in obstructive bowel disorders (OBD). However, whether alteration in ICC network is a cause or consequence of OBD remains unknown. This study tested the hypothesis that mechanical dilation in obstruction disrupts the ICC network and that ICC do not mediate mechanotranscription of COX-2 and impairment of smooth muscle contractility in obstruction.MethodsMedical-grade silicon bands were wrapped around the distal colon to induce partial obstruction in wild-type and ICC deficient (W/Wv) mice.ResultsIn wild-type mice, colon obstruction led to time-dependent alterations of the ICC network in the proximal colon segment. Although unaffected on days 1 and 3, the ICC density decreased markedly and the network was disrupted on day 7 of obstruction. COX-2 expression increased, and circular muscle contractility decreased significantly in the segment proximal to obstruction. In W/Wv control mice, COX-2 mRNA level was 4.0 (±1.1)-fold higher (n=4) and circular muscle contractility was lower than in wild-type control mice. Obstruction further increased COX-2 mRNA level in W/Wv mice to 7.2 (±1.0)-fold vs. W/Wv controls [28.8 (±4.1)-fold vs. wild-type controls] on day 3. Obstruction further suppressed smooth muscle contractility in W/Wv mice. However, daily administration of COX-2 inhibitor NS-398 significantly improved muscle contractility in both W/Wv sham and obstruction mice.ConclusionsLumen dilation disrupts the ICC network. ICC deficiency has limited effect on stretch-induced expression of COX-2 and suppression of smooth muscle contractility in obstruction. Rather, stretch-induced COX-2 plays a critical role in motility dysfunction in partial colon obstruction.

Numerical metrics for automated quantification of interstitial cell of Cajal network structural properties

Depletion of interstitial cells of Cajal (ICC) networks is known to occur in several gastrointestinal motility disorders. Although confocal microscopy can effectively image and visualize the spatial distribution of ICC networks, current descriptors of ICC depletion are limited to cell numbers and volume computations. Spatial changes in ICC network structural properties have not been quantified. Given that ICC generate electrical signals, the organization of a network may also affect physiology. In this study, six numerical metrics were formulated to automatically determine complex ICC network structural properties from confocal images: density, thickness, hole size, contact ratio, connectivity and anisotropy. These metrics were validated and applied in proof-of-concept studies to quantitatively determine jejunal ICC network changes in mouse models with decreased (5-HT2B receptor knockout (KO)) and normal (Ano1 KO) ICC numbers, and during post-natal network maturation. Results revealed a novel remodelling phenomenon occurring during ICC depletion, namely a spatial rearrangement of ICC and the preferential longitudinal alignment. In the post-natal networks, an apparent pruning of the ICC network was demonstrated. The metrics developed here enabled the first detailed quantitative analyses of structural changes that may occur in ICC networks during depletion and development.

Interstitial cells of Cajal plasticity rather than regeneration restores slow-wave activity and enteric neurotransmission upon acute damage

Background The enteric nervous system contains excitatory and inhibitory neurons which control contraction and relaxation of smooth muscle cells and gastrointestinal (GI) motor activity. Nitric oxide (NO) plays an important role as a nonadrenergic non-cholinergic inhibitory neurotransmitter in the enteric nervous system, which activates the NO-GC/ cGMP/PKG signalling pathway and thus relaxation of the smooth musclulature in the GI tract. Interstitial cells of Cajal (ICC) act as pacemaker cells in the GI tract by generating slow waves of depolarisation to induce rhythmic smooth muscle contractions. In addition, our previous work established a surprising role of ICCs in excitatory and inhibitory nitrergic neurotransmission. The aim of the present study was to investigate molecular and cellular mechanisms, which mediate regeneration of intestinal slow-waves and inhibitory nitrergic neurotransmission upon acute damage of the ICC network.

Distribution of interstitial cells of Cajal in Meriones unguiculatus and alterations in the development of incomplete intestinal obstruction.

The interstitial cells of Cajal (ICCs) act as pacemaker cells that are involved in gastrointestinal (GI) motility disorders, although the pathogenesis of these disorders is still unclear. The GI tract of Mongolian gerbils shares similar anatomical features with that of humans, but no investigation of ICCs has been reported in the GI tracts of this animal. In the present study, we first observed the distribution and morphological features of ICCs in the Mongolian gerbil GI tract. The ICCs were mainly distributed within the smooth muscle layers (ICC-IM), the myenteric plexus (ICC-MY), the deep muscular plexus in the small intestine (ICC-DMP) and the submucosal surface of the circular muscle layer in the colon (ICC-SM). The density of the ICC-IM gradually decreased from the stomach to the colon, whereas the density of the ICC-MY gradually increased. Second, we compared differences in the ICCs between the control and obstructed intestines, and no significant difference was observed in the number of ICCs after 7 days of obstruction. However, the numbers were reduced by approximately day 14 of obstruction. The pattern of immunoreactivity also partly differed from that of the control group, i.e., a scattered and interrupted network of ICCs was often observed. Western blotting revealed that p-Kit and SCF were significantly reduced in the dilated intestines by day 14. Our results indicate that the Mongolian gerbil may be a good animal model for studying changes in ICCs that may contribute to the pathogenesis of GI motility disorders.

Establishment of pacemaker activity in tissues allotransplanted with interstitial cells of Cajal

Loss or disruption of Kit(+) -interstitial cells of Cajal (ICC) capable of generating pacemaker activity has been implicated in the development of numerous gastrointestinal motility disorders. We sought to develop a model where ICC could be allotransplanted into intestines naturally devoid of these cells. Enzymatically dispersed cells from the intestinal tunica muscularis of Kit(+/copGFP) and Kit(V558Δ) /+ gain-of-function mice were allotransplanted into myenteric plexus regions of W/W(V) mutant intestines that lack ICC at the level of the myenteric plexus (ICC-MY) and pacemaker activity. Immunohistochemical analysis fate mapped the development of ICC-MY networks and intracellular microelectrode recordings provided evidence for the development of functional pacemaker activity. Kit(+) -ICC developed into distinct networks at the level of the myenteric plexus in organotypic cultures over 28days and displayed robust rhythmic pacemaker activity. This study demonstrates the feasibility of allotransplantation of ICC into the myenteric region of the small intestine and the establishment of functional pacemaker activity into tissues normally devoid of ICC-MY and slow waves, thus providing a possible basis for the therapeutic treatment of patients where ICC networks have been disrupted due to a variety of pathophysiological conditions.

Impaired heme oxygenase‐1 induction in the gastric antrum induces disruption of the interstitial cells of Cajal network in a rat model of streptozotocin‐induced diabetes

Streptozotocin (STZ) is known to induce type I diabetes and the loss of the interstitial cells of Cajal (ICC). However, the regulation of heme oxygenase-1 (HO-1) expression, which is reported to protect ICC, has not yet been elucidated in this model. The aim of this study was to investigate the alterations of HO-1 expression and clarify the mechanism of ICC loss in the stomach using the rat model of STZ-induced diabetes. Streptozotocin (65mgkg(-1) ) was intraperitoneally administered to 8-week-old female Wistar rats. Cobalt protoporphyrin (CoPP), an HO-1 inducer, was administered subcutaneously once a week after the STZ injection. The expressions of HO-1 and the receptor tyrosine kinase c-Kit (a marker for ICC) proteins were investigated by western blot analysis and immunofluorescence staining. Expression of c-Kit, particularly in the gastric antrum, was significantly decreased at 8weeks, not at 1week, compared to those of the control group. Significantly increased induction of HO-1 expression, especially in the gastric corpus but not in the antrum, was observed in the STZ group at 8weeks after the STZ injection relative to control. CoPP administration significantly up-regulated HO-1 expression in the STZ diabetic group and significantly restored the previously reduced ICC in the gastric antrum. Up-regulation of HO-1 expression in the STZ diabetic model was limited to the gastric corpus and impaired up-regulation of HO-1 expression in the gastric antrum likely induced the disruption of the ICC network.

Kit Signaling Is Required for Development of Coordinated Motility Patterns in Zebrafish Gastrointestinal Tract

Interstitial cells of Cajal (ICC) provide a pacemaker signal for coordinated motility patterns in the mammalian gastrointestinal (GI) tract. Kit signaling is required for development and maintenance of ICC, and these cells can be identified by Kit-like immunoreactivity. The zebrafish GI tract has two distinct ICC networks similar to mammals, suggesting a similar role in the generation of GI motility; however, a functional role for Kit-positive cells in zebrafish has not been determined. Analysis of GI motility in intact zebrafish larvae was performed during development and after disruption of Kit signaling. Development of coordinated motility patterns occurred after 5 days post-fertilization (dpf) and correlated with appearance of Kit-positive cells. Disruptions of Kit signaling using the Kit antagonist imatinib mesylate, and in Sparse, a null kita mutant, also disrupted development of coordinated motility patterns. These data suggest that Kit signaling is necessary for development of coordinated motility patterns and that Kit-positive cells in zebrafish are necessary for coordinated motility patterns.

On the origin of rhythmic contractile activity of the esophagus in early achalasia, a clinical case study

A patient with early achalasia presented spontaneous strong rhythmic non-propulsive contractions at ~7/min, independent of swallows. Our aim was to evaluate characteristics of the rhythmic contractions, provide data on the structure of pacemaker cells in the esophagus and discuss a potential role for interstitial cells of Cajal (ICC) in the origin of rhythmicity. We hypothesize that intramuscular ICC (ICC-IM) are the primary pacemaker cells. The frequency but not the amplitude of the rhythmic contractions was inhibited by the phosphodiesterase inhibitor drotaverine consistent with cAMP inhibiting pacemaker currents in ICC-IM. The frequency increased by wet swallows but not dry swallows, consistent with stretch causing increase in slow wave frequency in ICC-IM. New studies on archival material showed that ICC-IM were present throughout the human esophageal musculature and were not diminished in early achalasia. Although ICC-IM exhibited a low density, they were connected to PDGFRα-positive fibroblast-like cells with whom they formed a dense gap junction coupled network. Nitrergic innervation of ICC was strongly diminished in early achalasia because of the loss of nitrergic nerves. It therefore appears possibly that ICC-IM function as pacemaker cells in the esophagus and that the network of ICC and PDGFRα-positive cells allows for coupling and propagation of the pacemaker activity. Loss of nitrergic innervation to ICC in achalasia may render them more excitable such that its pacemaker activity is more easily expressed. Loss of propagation in achalasia may be due to loss of contraction-induced aboral nitrergic inhibition.

Disruption of interstitial cells of Cajal networks after massive small bowel resection

To investigate the disruptions of interstitial cells of Cajal (ICC) in the remaining bowel in rats after massive small bowel resection (mSBR). Thirty male Sprague-Dawley rats fitting entry criteria were divided randomly into three experimental groups (n = 10 each): Group A rats underwent bowel transection and re-anastomosis (sham) and tissue samples were harvested at day 7 post-surgery. Group B and C rats underwent 80% small bowel resection with tissue harvested from Group B rats at day 7 post-surgery, and from Group C rats at day 14 post-surgery. The distribution of ICC at the site of the residual small bowel was evaluated by immunohistochemical analysis of small intestine samples. The ultrastructural changes of ICC in the remnant ileum of model rats 7 and 14 d after mSBR were analyzed by transmission electron microscopy. Intracellular recordings of slow wave oscillations were used to evaluate electrical pacemaking. The protein expression of c-kit, ICC phenotypic markers, and membrane-bound stem cell factor (mSCF) in intestinal smooth muscle of each group were detected by Western blotting. After mSBR, immunohistochemical analysis indicated that the number of c-kit-positive cells was dramatically decreased in Group B rats compared with sham tissues. Significant ultrastructural changes in ICC with associated smooth muscle hypertrophy were also observed. Disordered spontaneous rhythmic contractions with reduced amplitude (8.5 ± 1.4 mV vs 24.8 ± 1.3 mV, P = 0.037) and increased slow wave frequency (39.5 ± 2.1 cycles/min vs 33.0 ± 1.3 cycles/min, P = 0.044) were found in the residual intestinal smooth muscle 7 d post mSBR. The contractile function and electrical activity of intestinal circular smooth muscle returned to normal levels at 14 d post mSBR (amplitude, 14.9 ± 1.6 mV vs 24.8 ± 1.3 mV; frequency, 30.7 ± 1.7 cycles/min vs 33.0 ± 1.3 cycles/min). The expression of Mscf and c-kit protein was decreased at 7 d (P = 0.026), but gradually returned to normal levels at 14 d. The ICC and associated neural networks were disrupted, which was associated with the phenotype alterations of ICC. Massive small bowel resection in rats triggered damage to ICC networks and decreased the number of ICC leading to disordered intestinal rhythmicity. The mSCF/c-kit signaling pathway plays a role in the regulation and maintenance of ICC phenotypes.