Blockade of kit signaling induces transdifferentiation of interstitial cells of cajal to a smooth muscle phenotype

A spatiotemporal and machine-learning platform facilitates the manufacturing of hPSC-derived esophageal mucosa

Human pluripotent stem cell-derived tissue engineering offers great promise for designer cell-based personalized therapeutics, but harnessing such potential requires a deeper understanding of tissue-level interactions. We previously developed a cell replacement manufacturing method for ectoderm-derived skin epithelium. However, it remains challenging to manufacture the endoderm-derived esophageal epithelium despite possessing a similar stratified epithelial structure. Here, we employ single-cell and spatial technologies to generate a spatiotemporal multi-omics cell census for human esophageal development. We identify the cellular diversity, dynamics, and signal communications for the developing esophageal epithelium and stroma. Using Manatee, a machine-learning algorithm, we prioritize the combinations of candidate human developmental signals for in vitro derivation of esophageal basal cells. Functional validation of Manatee predictions leads to a clinically compatible system for manufacturing human esophageal mucosa.

Revealing a coherent cell state landscape across single cell datasets with CONCORD

Batch integration, denoising, and dimensionality reduction remain fundamental challenges in single-cell data analysis. While many machine learning tools aim to overcome these challenges by engineering model architectures, we use a different strategy, building on the insight that optimized mini-batch sampling during training can profoundly influence learning outcomes. We present CONCORD, a self-supervised learning approach that implements a unified, probabilistic data sampling scheme combining neighborhood-aware and dataset-aware sampling: the former enhancing resolution while the latter removing batch effects. Using only a minimalist one-hidden-layer neural network and contrastive learning, CONCORD achieves state-of-the-art performance without relying on deep architectures, auxiliary losses, or supervision. It generates high-resolution cell atlases that seamlessly integrate data across batches, technologies, and species, without relying on prior assumptions about data structure. The resulting latent representations are denoised, interpretable, and biologically meaningful-capturing gene co-expression programs, resolving subtle cellular states, and preserving both local geometric relationships and global topological organization. We demonstrate CONCORD's broad applicability across diverse datasets, establishing it as a general-purpose framework for learning unified, high-fidelity representations of cellular identity and dynamics.

Effect and mechanism of Lycium barbarum polysaccharide on gastrointestinal motility in slow transit constipation

Slow transit constipation (STC) seriously affects the physical and mental health of patients. While the active ingredients of traditional Chinese medicine (TCM) are widely used in the treatment of STC due to their low toxicity and side effects, the aim of this study was to investigate the effect of Lycium barbarum polysaccharide (LBP) on STC. The STC mouse model was induced by the compound diphenoxylate. Defecation, fecal moisture, and weight loss of the STC models were monitored. Gastrointestinal (GI) motility was assessed by intestinal propulsive rate, and enzyme-linked immunosorbent assay (ELISA) kits were used to analyze the levels of substance P (SP) and vasoactive intestinal peptide (VIP). The expression levels of inflammatory cytokines (Tnf-α, Il-6, and Il-1β), stem cell factor receptor (C-kit), stem cell factor (Scf), Bcl-2, Bax, and Caspase-3 were evaluated by qRT-PCR. The defecation, fecal moisture, and body weight of mice with STC were significantly improved by LBP, and LBP increased the intestinal propulsive rate of STC, increased the secretion of SP, and decreased the secretion of VIP. The intervention of LBP further suppressed the expression levels of Tnf-α, Il-6, and Il-1β in STC. LBP promoted the expression of the C-kit, Scf, and Bcl-2 and inhibited the expression of Bax and Caspase-3. LBP may alleviate symptoms of slow transit constipation (STC) and enhance gastrointestinal motility by modulating gastrointestinal hormone levels, promoting proliferation, and inhibiting the apoptosis of interstitial cells of Cajal (ICCs).

Causes and consequences: development and pathophysiology of Hirschsprung disease

Hirschsprung disease (HSCR) is a congenital enteric neuropathy in which the enteric nervous system (ENS) fails to develop along variable lengths of the distal gastrointestinal (GI) tract. This aganglionosis results in a functional bowel obstruction and requires surgical resection of the aganglionic segment. Despite surgery, however, long-term bowel dysfunction affects many patients. Understanding the embryologic causes and pathophysiologic consequences of HSCR is critical to improving its diagnosis and treatment. During normal gut development, the ENS arises from neural crest cells (NCCs) that delaminate from the neural tube to populate the entire GI tract with enteric neurons and glia. This process requires NCCs to undergo proliferation, migration and differentiation to form the complex neuroglial network that regulates gut motility and other intestinal functions. This review discusses the cellular and molecular processes that control normal ENS formation and what goes awry to give rise to HSCR. The complex pathophysiologic consequences of aganglionosis are discussed, including recent observations that describe novel aspects of HSCR beyond the absence of ganglion cells. This review aims to expand the understanding of HSCR and to stimulate new ideas on how to improve current management of the disease.

A bibliometric analysis of diabetic gastroparesis from 1979 to 2024

Objective

Gastroparesis is one of the complications of diabetes mellitus, which has a major impact on the quality of life of patients, and the limited therapeutic options currently available make it a public health problem. No bibliometric studies on diabetic gastroparesis have been published to date. Therefore, the aim of this paper is to summarize and analyze the research hotspots for researchers.

Methods

Research articles related to Diabetic gastroparesis were searched in Web of Science Core Collection (WOSCC), and relevant information was extracted after screening. A comprehensive bibliometric analysis of 699 publications was conducted using Microsoft Excel 2019, Citespace and VOSviewers.

Result

A total of 699 papers from 738 institutions in 41 countries were retrieved. Publications in this field have increased rapidly since 1979. USA (n = 370) and Mayo Clinical (n = 69) were the most productive country and institution, respectively. Neurogastroenterology and Motility (n = 67) was the most published journal with Parkman, Henry P. (n = 40) having the highest number of articles; Gastroenterology and Mccallum, Richard W. were the most influential journals and authors.

Conclusions

The research hotspots of Diabetic gastroparesis are mainly focused on treatment modalities and pathological mechanisms. Future research in diabetic gastroparesis will focus on exploring the pathomechanisms, finding long-term effective treatments, and improving patients' quality of life.

Hyper-Dependence on NHEJ Enables Synergy between DNA-PK Inhibitors and Low-Dose Doxorubicin in Leiomyosarcoma

PURPOSE

Leiomyosarcoma (LMS) is an aggressive sarcoma for which standard chemotherapies achieve response rates under 30%. There are no effective targeted therapies against LMS. Most LMS are characterized by chromosomal instability (CIN), resulting in part from TP53 and RB1 co-inactivation and DNA damage repair defects. We sought to identify therapeutic targets that could exacerbate intrinsic CIN and DNA damage in LMS, inducing lethal genotoxicity.

EXPERIMENTAL DESIGN

We performed clinical targeted sequencing in 287 LMS and genome-wide loss-of-function screens in 3 patient-derived LMS cell lines, to identify LMS-specific dependencies. We validated candidate targets by biochemical and cell-response assays in vitro and in seven mouse models.

RESULTS

Clinical targeted sequencing revealed a high burden of somatic copy-number alterations (median fraction of the genome altered =0.62) and demonstrated homologous recombination deficiency signatures in 35% of LMS. Genome-wide short hairpin RNA screens demonstrated PRKDC (DNA-PKcs) and RPA2 essentiality, consistent with compensatory nonhomologous end joining (NHEJ) hyper-dependence. DNA-PK inhibitor combinations with unconventionally low-dose doxorubicin had synergistic activity in LMS in vitro models. Combination therapy with peposertib and low-dose doxorubicin (standard or liposomal formulations) inhibited growth of 5 of 7 LMS mouse models without toxicity.

CONCLUSIONS

Combinations of DNA-PK inhibitors with unconventionally low, sensitizing, doxorubicin dosing showed synergistic effects in LMS in vitro and in vivo models, without discernable toxicity. These findings underscore the relevance of DNA damage repair alterations in LMS pathogenesis and identify dependence on NHEJ as a clinically actionable vulnerability in LMS.

A Spatiotemporal and Machine-Learning Platform Accelerates the Manufacturing of hPSC-derived Esophageal Mucosa

Human pluripotent stem cell-derived tissue engineering offers great promise in designer cell-based personalized therapeutics. To harness such potential, a broader approach requires a deeper understanding of tissue-level interactions. We previously developed a manufacturing system for the ectoderm-derived skin epithelium for cell replacement therapy. However, it remains challenging to manufacture the endoderm-derived esophageal epithelium, despite both possessing similar stratified structure. Here we employ single cell and spatial technologies to generate a spatiotemporal multi-omics cell atlas for human esophageal development. We illuminate the cellular diversity, dynamics and signal communications for the developing esophageal epithelium and stroma. Using the machine-learning based Manatee, we prioritize the combinations of candidate human developmental signals for in vitro derivation of esophageal basal cells. Functional validation of the Manatee predictions leads to a clinically-compatible system for manufacturing human esophageal mucosa. Our approach creates a versatile platform to accelerate human tissue manufacturing for future cell replacement therapies to treat human genetic defects and wounds.

Chemotherapy-induced gastrointestinal toxicity: Pathogenesis and current management

Chemotherapy is the most common treatment for malignant tumors. However, chemotherapy-induced gastrointestinal toxicity (CIGT) has been a major concern for cancer patients, which reduces their quality of life and leads to treatment intolerance and even cessation. Nevertheless, prevention and treatment for CIGT are challenging, due to the prevalence and complexity of the condition. Chemotherapeutic drugs directly damage gastrointestinal mucosa to induce CIGT, including nausea, vomiting, anorexia, gastrointestinal mucositis, and diarrhea, etc. The pathogenesis of CIGT involves multiple factors, such as gut microbiota disorders, inflammatory responses and abnormal neurotransmitter levels, that synergistically contribute to its occurrence and development. In particular, the dysbiosis of gut microbiota is usually linked to abnormal immune responses that increases inflammatory cytokines' expression, which is a common characteristic of many types of CIGT. Chemotherapy-induced intestinal neurotoxicity is also a vital concern in CIGT. Currently, modern medicine is the dominant treatment of CIGT, however, traditional Chinese medicine (TCM) has attracted interest as a complementary and alternative therapy that can greatly alleviate CIGT. Accordingly, this review aimed to comprehensively summarize the pathogenesis and current management of CIGT using PubMed and Google Scholar databases, and proposed that future research for CIGT should focus on the gut microbiota, intestinal neurotoxicity, and promising TCM therapies, which may help to develop more effective interventions and optimize managements of CIGT.

Multi-disciplinary Insights from the First European Forum on Visceral Myopathy 2022 Meeting

Visceral myopathy is a rare, life-threatening disease linked to identified genetic mutations in 60% of cases. Mostly due to the dearth of knowledge regarding its pathogenesis, effective treatments are lacking. The disease is most commonly diagnosed in children with recurrent or persistent disabling episodes of functional intestinal obstruction, which can be life threatening, often requiring long-term parenteral or specialized enteral nutritional support. Although these interventions are undisputedly life-saving as they allow affected individuals to avoid malnutrition and related complications, they also seriously compromise their quality of life and can carry the risk of sepsis and thrombosis. Animal models for visceral myopathy, which could be crucial for advancing the scientific knowledge of this condition, are scarce. Clearly, a collaborative network is needed to develop research plans to clarify genotype-phenotype correlations and unravel molecular mechanisms to provide targeted therapeutic strategies. This paper represents a summary report of the first 'European Forum on Visceral Myopathy'. This forum was attended by an international interdisciplinary working group that met to better understand visceral myopathy and foster interaction among scientists actively involved in the field and clinicians who specialize in care of people with visceral myopathy.

Constipation in DM are associated with both poor glycemic control and diabetic complications: Current status and future directions

Constipation is a major complications of diabetes mellitus. With the accelerating prevalence of diabetes worldwide and an aging population, there is considerable research interest regarding the altered function and structure of the gastrointestinal tract in diabetic patients. Despite current advances in hyperglycemic treatment strategies, the specific pathogenesis of diabetic constipation remains unknown. Patients with constipation, may be reluctant to eat regularly, which may worsen glycemic control and thus worsen symptoms associated with underlying diabetic bowel disease. This paper presents a review of the complex relationship between diabetes and constipation, exploring the morphological alterations and biomechanical remodeling associated with intestinal motility dysfunction, as well as alterations in intestinal neurons, cellular signaling pathways, and oxidative stress. Further studies focusing on new targets that may play a role in the pathogenesis of diabetic constipation may, provide new ideas for the development of novel therapies to treat or even prevent diabetic constipation.

Gastroparesis and Gastroparesis Syndromes as Neuromuscular Disorders

Gastroparesis syndromes (GpS) are a spectrum of disorders presenting with characteristic symptoms increasingly recognized as being gastrointestinal (GI) neuromuscular disorders (NMDs). This review focuses on GpS as a manifestation of neurologic disorders of GI NMD. GpS can be associated with systemic abnormalities, including inflammatory, metabolic, and serologic disorders, as well as autoimmune antibodies via nerve and muscle targets in the GI tract, which can be treated with immunotherapy, such as intravenous immunoglobulin. GpS are associated with autonomic (ANS) and enteric (ENS) dysfunction. Disorders of ANS may interact with the ENS and are the subject of continued investigation. ENS disorders have been recognized for a century but have only recently begun to be fully quantified. Anatomic structural changes in the GI tract are increasingly recognized in GpS. Detailed descriptions of anatomic changes in GpS, and their correlation with physiologic findings, have opened a new era of investigation. The management of GpS, when viewed as GI NMD, has shifted the paradigms of both diagnosis and treatment. This article concludes with current approaches to GpS directed at underlying neuromuscular pathology.

LIX1 Controls MAPK Signaling Reactivation and Contributes to GIST-T1 Cell Resistance to Imatinib

Gastrointestinal stromal tumor (GIST), the most common sarcoma, is mainly caused by an oncogenic mutation in the KIT receptor tyrosine kinase. Targeting KIT using tyrosine kinase inhibitors, such as imatinib and sunitinib, provides substantial benefit; however, in most patients, the disease will eventually progress due to KIT secondary mutations leading to treatment failure. Understanding how GIST cells initially adapt to KIT inhibition should guide the selection of appropriate therapies to overcome the emergence of resistance. Several mechanisms have been broadly implicated in the resistance to imatinib anti-tumoral effects, including the reactivation of MAPK signaling upon KIT/PDGFRA targeted inhibition. This study provides evidence that LImb eXpression 1 (LIX1), a protein we identified as a regulator of the Hippo transducers YAP1 and TAZ, is upregulated upon imatinib or sunitinib treatment. LIX1 silencing in GIST-T1 cells impaired imatinib-induced MAPK signaling reactivation and enhanced imatinib anti-tumor effect. Our findings identified LIX1 as a key regulator of the early adaptative response of GIST cells to targeted therapies.

Yunvjian Improves Glucose and Insulin Function in Diabetic Rats by Regulating Gastric Emptying Function

BACKGROUND

Diet acts on the human body through digestion in the stomach and absorption in the intestines. Thus, the emptying of the stomach should be the focus of the research mechanism of the combined medicine and food treatment of diabetes. The emptying function of the stomach and the secretion of related hormones may be the key points of traditional Chinese medicine. In the clinic, Yunvjian is a famous traditional Chinese formula for preventing and curing diabetes. However, the pharmacological action and mechanism of Yunvjian are also need to be probe.

OBJECTIVE

To assess the effect of Yunvjian on glucose, insulin level and gastric emptying function and related hormones on high-fat diet combined with STZ-induced diabetic rats.

METHODS

High-fat diet combined with STZ was used to construct type 2 diabetes mellitus (T2DM) rats model and received a 4-week Yunvjian administration. The animals were divided into 6 groups, respectively, as the Control group, the DM group, the DM + Acarbose group, the DM + YNH group, and the DM + YNL group. Radionuclide single-photon emission computed tomography (SPECT) technology was used to observe the gastric emptying rate and half-empty time; blood was took to test fasting insulin, and then the insulin resistance index (HOMA-IR) was calculated; HE staining was performed to detect islets and gastric antrum, immunohistochemical staining was performed to detect the number and morphology of pancreatic β cells and gastric antrum Cajal cells, and the average optical density was calculated; the expression of ghrelin hormone in gastric antrum and serum was detected by ELISA and immunofluorescence; the expression of GHRS mRNA in gastric antrum was detected by RT-PCR method.

RESULTS

Yunvjian could significantly improve the glucose level and insulin function of rats. Compared with the DM group, Yunvjian was beneficial to low fasting blood glucose (FBG) (P < 0.01), increased glucose tolerance, and improved islet function at the same time (P < 0.05). At the same time, compared with the DM group (25.02 ± 0.05, 44 ± 12.33), the emptying rate of the DM + YNH group was significantly faster (64.98 ± 0.12), and the half row time was shortened (26 ± 8.29, P < 0.05). The gastric ghrelin levels in each group of Yunvjian increased with different degrees compared with the DM group (616.2 ± 26.23), especially in the DM + YNH group (863.51 ± 23.76, P < 0.01). Correspondingly, the expression of gastric GHSR mRNA in the DM + YNH and DM + YNL groups increased significantly compared with the DM group (P < 0.01).

CONCLUSIONS

Yunvjian can effectively control glucose and improve islet function, which may be closely related to its influence on gastric emptying function and related hormone secretion regulation.

Single Nucleus Sequencing of Human Colon Myenteric Plexus-Associated Visceral Smooth Muscle Cells, Platelet Derived Growth Factor Receptor Alpha Cells, and Interstitial Cells of Cajal

BACKGROUND AND AIMS

Smooth muscle cells (SMCs), interstitial cells of Cajal (ICCs), and platelet-derived growth factor receptor alpha (PDGFRα+) cells (PαCs) form a functional syncytium in the bowel known as the "SIP syncytium." The SIP syncytium works in concert with the enteric nervous system (ENS) to coordinate bowel motility. However, our understanding of individual cell types that form this syncytium and how they interact with each other remains limited, with no prior single-cell RNAseq analyses focused on human SIP syncytium cells.

METHODS

We analyzed single-nucleus RNA sequencing data from 10,749 human colon SIP syncytium cells (5572 SMC, 372 ICC, and 4805 PαC nuclei) derived from 15 individuals.

RESULTS

Consistent with critical contractile and pacemaker functions and with known enteric nervous system interactions, SIP syncytium cell types express many ion channels, including mechanosensitive channels in ICCs and PαCs. PαCs also prominently express extracellular matrix-associated genes and the inhibitory neurotransmitter receptor for vasoactive intestinal peptide (VIPR2), a novel finding. We identified 2 PαC clusters that differ in the expression of many ion channels and transcriptional regulators. Interestingly, SIP syncytium cells co-express 6 transcription factors (FOS, MEIS1, MEIS2, PBX1, SCMH1, and ZBTB16) that may be part of a combinatorial signature that specifies these cells. Bowel region-specific differences in SIP syncytium gene expression may correlate with regional differences in function, with right (ascending) colon SMCs and PαCs expressing more transcriptional regulators and ion channels than SMCs and PαCs in left (sigmoid) colon.

CONCLUSION

These studies provide new insights into SIP syncytium biology that may be valuable for understanding bowel motility disorders and lead to future investigation of highlighted genes and pathways.

Histiocytic Sarcoma Secondary to Gastrointestinal Stromal Tumors: A Literature Review

Histiocytic sarcoma (HS) is a rare tumor that may result from the transdifferentiation of preexisting hematolymphoid neoplasms in a subset of patients. There are instances of correlation or concurrence between HS and a number of cancers, particularly B-cell-associated hematopoietic tumors. Only three cases of HS occurring subsequent to or concurrently with gastrointestinal stromal tumors (GIST) have been recorded. Our main objective was to give an overview of demographics, clinical signs and symptoms, histopathological findings, and immunohistochemical and molecular analysis when HS develops secondary to or concurrently with GIST. A search of PubMed, Google Scholar, and ScienceDirect was undertaken using Medical Subject Headings (MeSH) keywords. According to the findings of our review, there were two males (66.6%) and one female (33.3%). The average age of patients at presentation was 59.6 years. On the immunohistochemistry, three patients were positive for cluster of differentiation (CD) 68 (100%), two patients were positive for CD 163 (67%), one patient was positive for leukocyte common antigen (LCA) (33%), and only one patient was positive for CD 4, CD 10, CD 31, CD 45, human leukocyte antigen (HLA)-DR, lysozyme, and vimentin (33%). On molecular investigation, the gastric mass of only one patient (33.33%) contained a KIT mutation on exon 11. Emperipolesis was observed in one patient (33.33%) on histological examination. Our study provides an important overview of the available literature and gives insight into important diagnostic markers of HS when it occurs secondary to or concurrently with GIST.

LIX1-mediated changes in mitochondrial metabolism control the fate of digestive mesenchyme-derived cells

YAP1 and TAZ are transcriptional co-activator proteins that play fundamental roles in many biological processes, from cell proliferation and cell lineage fate determination to tumorigenesis. We previously demonstrated that Limb Expression 1 (LIX1) regulates YAP1 and TAZ activity and controls digestive mesenchymal progenitor proliferation. However, LIX1 mode of action remains elusive. Here, we found that endogenous LIX1 is localized in mitochondria and is anchored to the outer mitochondrial membrane through S-palmitoylation of cysteine 84, a residue conserved in all LIX1 orthologs. LIX1 downregulation altered the mitochondrial ultrastructure, resulting in a significantly decreased respiration and attenuated production of mitochondrial reactive oxygen species (mtROS). Mechanistically, LIX1 knock-down impaired the stability of the mitochondrial proteins PHB2 and OPA1 that are found in complexes with mitochondrial-specific phospholipids and are required for cristae organization. Supplementation with unsaturated fatty acids counteracted the effects of LIX1 knock-down on mitochondrial morphology and ultrastructure and restored YAP1/TAZ signaling. Collectively, our data demonstrate that LIX1 is a key regulator of cristae organization, modulating mtROS level and subsequently regulating the signaling cascades that control fate commitment of digestive mesenchyme-derived cells.

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LIX1 is tightly anchored to the outer membrane of mitochondria.

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LIX1 mitochondrial localization is mediated by S-palmitoylation on cysteine 84.

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LIX1 knock-down reduces the stability of the mitochondrial proteins PHB2 and OPA1 and impairs cristae organization.

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Redox signaling modulations regulate YAP1/TAZ activity and control fate commitment of digestive mesenchyme-derived cells.

Relationship between gallstones and interstitial cells of Cajal in the gallbladder

INTRODUCTION

A high percentage of patients with gallstones exhibit abnormalities in gallbladder emptying, and gallstones are often associated with gallbladder contraction. Interstitial cells of Cajal (ICC) in the gallbladder are involved in the generation and spreading of spontaneous contractions of the gallbladder. This study examined the relationship among the number of gallbladder ICC, gallbladder contractility, and gallstones.

MATERIALS AND METHODS

Forty-six patients, who underwent cholecystectomy within 3 months of enduring a gallbladder ejection fraction scan, were enrolled in this study. ICC were identified using a microscope after immunohistochemical staining for CD117/c-kit. Five high-power field (magnification 400×) units were randomly assigned, and the number of ICC in the mucosal and muscular layers was counted. These counts were compared according to the sex, age, reason for cholecystectomy, presence of gallstone, presence of gallbladder polyp, gallbladder ejection fraction, and gallbladder size for each patient.

RESULTS

The number of ICC in the mucosal layer was increased in the male participants (154.4 ± 73.9) compared with the female participants (107.3 ± 75.2); however, the ICC in the muscular layer was not different between the 2 groups. Additionally, the ICC in the mucosal and muscular layers did not differ according to age, cause of cholecystectomy, number of stones, stone character, stone diameter, or the presence of polyps. A larger gallbladder size was correlated with a decreased number of ICC in the muscular layer of the gallbladder. Additionally, when the number of gallbladder stones was increased, the number of ICC in the muscular layer of the gallbladder was decreased; however, there was no significant correlation between the number of ICC in the mucosal layer of the gallbladder and any of the following factors: age, GBEF, gallbladder size, stone number, or diameter. Furthermore, there was no significant correlation between the number of ICC in the muscular layer of the gallbladder, regardless of age, GBEF, and stone diameter.

CONCLUSION

Although we were unable to achieve significant results regarding the relationship between GBEF and ICC, this is the first human study to reveal the relationship among ICC, gallbladder size, and the number of gallstones.

Single-cell RNA sequencing predicts motility networks in purified human gastric interstitial cells of Cajal

BACKGROUND

Gastrointestinal (GI) motility disorders affect millions of people worldwide, yet they remain poorly treated in part due to insufficient knowledge of the molecular networks controlling GI motility. Interstitial cells of Cajal (ICC) are critical GI pacemaker cells, and abnormalities in ICC are implicated in GI motility disorders. Two cell surface proteins, KIT and ANO1, are used for identifying ICC. However, difficulties accessing human tissue and the low frequency of ICC in GI tissues have meant human ICC are insufficiently characterized. Here, a range of characterization assays including single-cell RNA sequencing (scRNA-seq) was performed using KIT⁺ CD45^- CD11B^- primary human gastric ICC to better understand networks controlling human ICC biology.

METHODS

Excess sleeve gastrectomy tissues were dissected; ICC were analyzed by immunofluorescence, fluorescence-activated cell sorting (FACSorting), real-time PCR, mass spectrometry, and scRNA-seq.

KEY RESULTS

Immunofluorescence identified ANO1⁺ /KIT⁺ cells throughout the gastric muscle. Compared to the FACSorted negative cells, PCR showed the KIT⁺ CD45^- CD11B^- ICC were enriched 28-fold in ANO1 expression (p < 0.01). scRNA-seq analysis of the KIT^- CD45⁺ CD11B⁺ and KIT⁺ CD45^- CD11B^- ICC revealed separate clusters of immune cells and ICC (respectively); cells in the ICC cluster expressed critical GI motility genes (eg, CAV1 and PRKG1). The scRNA-seq data for these two cell clusters predicted protein interaction networks consistent with immune cell and ICC biology, respectively.

CONCLUSIONS & INFERENCES

The single-cell transcriptome of purified KIT⁺ CD45^- CD11B^- human gastric ICC presented here provides new molecular insights and hypotheses into evolving models of GI motility. This knowledge will provide an improved framework to investigate targeted therapies for GI motility disorders.

Interstitial cells of Cajal and human colon motility in health and disease

Our understanding of human colonic motility, and autonomic reflexes that generate motor patterns, has increased markedly through high-resolution manometry. Details of the motor patterns are emerging related to frequency and propagation characteristics that allow linkage to interstitial cells of Cajal (ICC) networks. In studies on colonic motor dysfunction requiring surgery, ICC are almost always abnormal or significantly reduced. However, there are still gaps in our knowledge about the role of ICC in the control of colonic motility and there is little understanding of a mechanistic link between ICC abnormalities and colonic motor dysfunction. This review will outline the various ICC networks in the human colon and their proven and likely associations with the enteric and extrinsic autonomic nervous systems. Based on our extensive knowledge of the role of ICC in the control of gastrointestinal motility of animal models and the human stomach and small intestine, we propose how ICC networks are underlying the motor patterns of the human colon. The role of ICC will be reviewed in the autonomic neural reflexes that evoke essential motor patterns for transit and defecation. Mechanisms underlying ICC injury, maintenance, and repair will be discussed. Hypotheses are formulated as to how ICC dysfunction can lead to motor abnormalities in slow transit constipation, chronic idiopathic pseudo-obstruction, Hirschsprung's disease, fecal incontinence, diverticular disease, and inflammatory conditions. Recent studies on ICC repair after injury hold promise for future therapies.

Circulating miRNAs as Biomarkers for Mitochondrial Neuro-Gastrointestinal Encephalomyopathy

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an ultra-rare disease for which there are currently no validated outcome measures for assessing therapeutic intervention efficacy. The aim of this study was to identify a plasma and/or serum microRNA (miRNA) biomarker panel for MNGIE. Sixty-five patients and 65 age and sex matched healthy controls were recruited and assigned to one of four study phases: (i) discovery for sample size determination; (ii) candidate screening; (iii) candidate validation; and (iv) verifying the performance of the validated miRNA panel in four patients treated with erythrocyte-encapsulated thymidine phosphorylase (EE-TP), an enzyme replacement under development for MNGIE. Quantitative PCR (qPCR) was used to profile miRNAs in serum and/or plasma samples collected for the discovery, validation and performance phases, and next generation sequencing (NGS) analysis was applied to serum samples assigned to the candidate screening phase. Forty-one differentially expressed candidate miRNAs were identified in the sera of patients (p < 0.05, log2 fold change > 1). The validation cohort revealed that of those, 27 miRNAs were upregulated in plasma and three miRNAs were upregulated in sera (p < 0.05). Through binary logistic regression analyses, five plasma miRNAs (miR-192-5p, miR-193a-5p, miR-194-5p, miR-215-5p and miR-34a-5p) and three serum miRNAs (miR-192-5p, miR-194-5p and miR-34a-5p) were shown to robustly distinguish MNGIE from healthy controls. Reduced longitudinal miRNA expression of miR-34a-5p was observed in all four patients treated with EE-TP and coincided with biochemical and clinical improvements. We recommend the inclusion of the plasma exploratory miRNA biomarker panel in future clinical trials of investigational therapies for MNGIE; it may have prognostic value for assessing clinical status.

Identification of CD44 as a Cell-Surface Marker for Kit Negative Interstitial Cells of Cajal in Adult Mouse Colon

Loss of Kit protein expression is proven to influence the plasticity of interstitial cells of Cajal (ICCs) and may contribute to gastrointestinal (GI) dysfunctions. The role and fate of Kit negative ICCs are unclear, and cell-specific markers for the Kit ICCs are unknown. In this study, we treated adult mice with imatinib (a Kit signaling blocker) for 8 or 16 days and investigated whether CD44 is a specific marker for the Kit negative ICCs in the adult mouse colon. We aimed at examining the protein and mRNA level of CD44 and Kit by using Western blot and real-time RT-PCR, respectively. Our results indicated that Kit expression was downregulated for both protein and mRNA levels after imatinib treatment for 8 or 16 days as compared to the vehicle-treated mice. Interestingly, CD44 expression remained unchanged throughout the treatment. Immunostaining on whole-mount preparations for Kit and CD44 showed that CD44 was exclusively co-localized with Kit in the ICCs of the vehicle-treated mouse colon. After imatinib treatment, a number of CD44+/Kit- cells with elaborated processes were observed with an evident decrease of Kit+ cell number within the muscular layers (ICC-IM) and around the myenteric nerve plexus (ICC-MY) as compared to vehicle-treated mice. After discontinuing imatinib for 16 days, Kit+ ICC-MY and ICC-IM were completely co-localized with normalization of CD44 and Kit+ cell numbers. Overall, our results identify CD44 as a cell-specific surface marker for Kit-ICCs and may be useful to understand the role and fate of Kit- ICCs in GI disorders.

A Rare Case of Histiocytic Sarcoma Secondary to Gastrointestinal Stromal Tumor in the Stomach: Transdifferentiation or Synchronicity?

Histiocytic sarcoma is a rare malignant histiocytic neoplasm composed of cells with morphologic and immunophenotypic features of mature tissue histiocytes. It occurs anywhere in the body and behaves aggressively. However, its etiology is unknown. Here, we report a 68-year-old female who developed histiocytic sarcoma following chemotherapy with imatinib (Gleevec) for gastrointestinal stromal tumor. Possible mechanisms of transdifferentiation from gastrointestinal stromal tumor to histiocytic sarcoma are discussed based on the features of our case and other two similar cases in the literature.

Phenotypic switch of smooth muscle cells in paediatric chronic intestinal pseudo-obstruction syndrome

Smooth Muscle Cells (SMC) are unique amongst all muscle cells in their capacity to modulate their phenotype. Indeed, SMCs do not terminally differentiate but instead harbour a remarkable capacity to dedifferentiate, switching between a quiescent contractile state and a highly proliferative and migratory phenotype, a quality often associated to SMC dysfunction. However, phenotypic plasticity remains poorly examined in the field of gastroenterology in particular in pathologies in which gut motor activity is impaired. Here, we assessed SMC status in biopsies of infants with chronic intestinal pseudo-obstruction (CIPO) syndrome, a life-threatening intestinal motility disorder. We showed that CIPO-SMCs harbour a decreased level of contractile markers. This phenotype is accompanied by an increase in Platelet-Derived Growth Factor Receptor-alpha (PDGFRA) expression. We showed that this modulation occurs without origin-related differences in CIPO circular and longitudinal-derived SMCs. As we characterized PDGFRA as a marker of digestive mesenchymal progenitors during embryogenesis, our results suggest a phenotypic switch of the CIPO-SMC towards an undifferentiated stage. The development of CIPO-SMC culture and the characterization of SMC phenotypic switch should enable us to design therapeutic approaches to promote SMC differentiation in CIPO.

A Close Relationship Between Networks of Interstitial Cells of Cajal and Gastrointestinal Transit In Vivo

The interstitial cells of Cajal associated with the myenteric plexus (ICC-MP) are located in the same area as the myenteric plexus. ICC-MP networks are linked to the generation of electrical pacemaker activity that causes spontaneous gastrointestinal (GI) contractions; however, its role in GI transit is not clear. The aim of this study was to comprehensively investigate the effect of ICC-MP disruption on GI transit in vivo using W/W^v mice, partially ICC-deficient model mice. In this study, we measured GI transit using a ¹³C-octanoic acid breath test, an orally administered dye and a bead expulsion assay. ICC were detected by immunohistochemical staining for c-Kit, a specific marker for ICC. Interestingly, we found that gastric emptying in W/W^v mice was normal. We also found that the ability of small intestinal and colonic transit was significantly reduced in W/W^v mice. Immunohistochemical staining using whole-mount muscularis samples revealed that c-Kit-positive ICC-MP networks were formed in wild-type mice. In contrast, ICC-MP networks in W/W^v mice were maintained only in the gastric antrum and were significantly reduced in the ileum and colon. No significant changes were observed in the nerve structures of the myenteric plexus in W/W^v mice. These findings suggest that ICC-MP contribute to GI transit as a powerful driving function in vivo.

The impact of acute stress disorder on gallbladder interstitial cells of Cajal

Physical and psychological stress exerts a substantial effect on gastrointestinal motility disorders, where trauma enhances symptoms of digestive dysfunction. Interstitial cells of Cajal (ICCs) act as pacemakers for gastrointestinal motility regulation and are likely important in stress-associated gastrointestinal motility disorders. This study explored the mechanisms underlying gallbladder ICCs function under acute stress conditions using a rabbit chest puncture and cholecystectomy model. The stem cell factor (SCF)/c-kit pathway is essential for the development of ICCs, and gene expression was investigated to identify stress-induced transcriptional alterations. Immunohistochemistry, terminal deoxynucleotidyl transferase dUTP nick end labeling assays were used to determine ICCs apoptosis, whereas western blot analysis and reverse-transcription polymerase chain reaction were used to detect changes in the SCF/c-kit signaling pathway. These methods revealed a reduction in ICCs via apoptosis following stress, and ICCs increased over time after stressor removal. Therefore, this study demonstrates the impact of stress on ICCs development and survival and further confirms the link between stress and gastrointestinal motility.

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.

LIX1 regulates YAP activity and controls gastrointestinal cancer cell plasticity

Gastrointestinal stromal tumours (GISTs), the most common mesenchymal neoplasm of the gastrointestinal tract, result from deregulated proliferation of transformed KIT‐positive interstitial cells of Cajal that share mesenchymal progenitors with smooth muscle cells. Despite the identification of selective KIT inhibitors, primary resistance and relapse remain a major concern. Moreover, most patients develop resistance partly through reactivation of KIT and its downstream signalling pathways. We previously identified the Limb Expression 1 (LIX1) gene as a unique marker of digestive mesenchyme immaturity. We also demonstrated that LIX1 regulates mesenchymal progenitor proliferation and differentiation by controlling the Hippo effector YAP1, which is constitutively activated in many sarcomas. Therefore, we wanted to determine LIX1 role in GIST development. We found that LIX1 is strongly up‐regulated in GIST samples and this is associated with unfavourable prognosis. Moreover, LIX1 controls GIST cell proliferation in vitro and in vivo. Upon LIX1 inactivation in GIST cells, YAP1/TAZ activity is reduced, KIT (the GIST signature) is down‐regulated, and cells acquire smooth muscle lineage features. Our data highlight LIX1 role in digestive mesenchyme‐derived cell‐fate decisions and identify this novel regulator as a target for drug design for GIST treatment by influencing its differentiation status.

Understanding the Biology of Human Interstitial Cells of Cajal in Gastrointestinal Motility

Millions of patients worldwide suffer from gastrointestinal (GI) motility disorders such as gastroparesis. These disorders typically include debilitating symptoms, such as chronic nausea and vomiting. As no cures are currently available, clinical care is limited to symptom management, while the underlying causes of impaired GI motility remain unaddressed. The efficient movement of contents through the GI tract is facilitated by peristalsis. These rhythmic slow waves of GI muscle contraction are mediated by several cell types, including smooth muscle cells, enteric neurons, telocytes, and specialised gut pacemaker cells called interstitial cells of Cajal (ICC). As ICC dysfunction or loss has been implicated in several GI motility disorders, ICC represent a potentially valuable therapeutic target. Due to their availability, murine ICC have been extensively studied at the molecular level using both normal and diseased GI tissue. In contrast, relatively little is known about the biology of human ICC or their involvement in GI disease pathogenesis. Here, we demonstrate human gastric tissue as a source of primary human cells with ICC phenotype. Further characterisation of these cells will provide new insights into human GI biology, with the potential for developing novel therapies to address the fundamental causes of GI dysmotility.

The roles of PDGFRα signaling in the postnatal development and functional maintenance of the SMC-ICC-PDGFRα+ cell (SIP) syncytium in the colon

BACKGROUND

The SIP syncytium in the gut consists of smooth muscle cells, interstitial cells of Cajal, and PDGFRα+ cells. We studied the fate of SIP cells after blocking PDGFRα receptor to explore the roles of PDGFRα signaling in the postnatal development and functional maintenance of the SIP syncytium.

METHODS

Crenolanib was administered to mice from P0, P10, or P50. The morphological changes in SIP cells were examined by immunofluorescence. Protein expression in SIP cells was detected by Western blotting. Moreover, colonic transit was analyzed by testing the colonic bead expulsion time.

KEY RESULTS

A dose of 5 mg(kg•day)^-1 crenolanib administered for 10 days beginning on P0 apparently hindered the development of PDGFRα+ cells in the colonic longitudinal muscularis and myenteric plexus without influencing their proliferative activity and apoptosis, but this result was not seen in the colonic circular muscularis. SMCs were also inhibited by crenolanib. A dose of 7.5 mg(kg•day)^-1 crenolanib administered for 15 days beginning on P0 caused reductions in both PDGFRα+ cells and ICC in the longitudinal muscularis, myenteric plexus, and circular muscularis. However, when crenolanib was administered at a dose of 5 mg(kg•day)^-1 beginning on P10 or P50, it only noticeably decreased the number of PDGFRα+ cells in the colonic longitudinal muscularis. Crenolanib also caused PDGFRα+ cells to transdifferentiate into SMC in adult mice. Colonic transit was delayed after administration of crenolanib.

CONCLUSIONS & INFERENCES

Therefore, PDGFRα signaling is essential for the development and functional maintenance of the SIP cells, especially PDGFRα+ cells.

Chick midgut morphogenesis

The gastrointestinal tract is an essential system of organs required for nutrient absorption. As a simple tube early in development, the primitive gut is patterned along its anterior-posterior axis into discrete compartments with unique morphologies relevant to their functions in the digestive process. These morphologies are acquired gradually through development as the gut is patterned by tissue interactions, both molecular and mechanical in nature, involving all three germ layers. With a focus on midgut morphogenesis, we review work in the chick embryo demonstrating how these molecular signals and mechanical forces sculpt the developing gut tube into its mature form. In particular, we highlight two mechanisms by which the midgut increases its absorptive surface area: looping and villification. Additionally, we review the differentiation and patterning of the intestinal mesoderm into the layers of smooth muscle that mechanically drive peristalsis and the villification process itself. Where relevant, we discuss the mechanisms of chick midgut morphogenesis in the context of experimental data from other model systems.

Neutrophils injure gallbladder interstitial Cajal-like cells in a guinea pig model of acute cholecystitis

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.

Acupuncture protects the interstitial cells of Cajal by regulating miR-222 in a rat model of post-operative ileus

BACKGROUND

Recovery of the interstitial cells of Cajal (ICCs) during post-operative ileus (POI) is important for the restoration of gastrointestinal (GI) motility. Acupuncture can protect ICCs, but the underlying mechanisms remain unclear. In this study, we investigated whether miR-222, c-kit and endothelial nitric oxide synthase (eNOS) are involved in the putative effects of acupuncture on ICC recovery.

METHODS

A POI model was established in Sprague-Dawley rats by colo-colic anastomosis, and then acupuncture was performed at bilateral ST36, SP6 and LR3 once daily for 3 consecutive days. C-kit protein expression in the colonic tissue adjacent to the incision site was determined by immunohistochemistry and Western blotting. mRNA levels of c-kit, eNOS and miR-222 were measured by real-time polymerase chain reaction (RT-PCR).

RESULTS

The levels of c-kit mRNA/protein and eNOS mRNA decreased, while miR-222 increased in the colonic tissues of POI model rats. Acupuncture treatment improved GI motility, inhibited the up-regulation of miR-222 and blocked the down-regulation of c-kit mRNA/protein and eNOS mRNA. The levels of miR-222 and c-kit were negatively correlated.

CONCLUSION

Acupuncture at ST36, SP6 and LR3 facilitates ICC recovery and improves post-operative GI motility in part through regulation of miR-222, c-kit and eNOS.

Gastrointestinal Dysmotility in MNGIE: from thymidine phosphorylase enzyme deficiency to altered interstitial cells of Cajal

Background

MNGIE is a rare and fatal disease in which absence of the enzyme thymidine phosphorylase induces systemic accumulation of thymidine and deoxyuridine and secondary mitochondrial DNA alterations. Gastrointestinal (GI) symptoms are frequently reported in MNGIE patients, however, they are not resolved with the current treatment interventions.

Recently, our understanding of the GI pathology has increased, which rationalizes the pursuit of more targeted therapeutic strategies. In particular, interstitial cells of Cajal (ICC) play key roles in GI physiology and are involved in the pathogenesis of the GI dysmotility. However, understanding of the triggers of ICC deficits in MNGIE is lacking. Herein, we review the current knowledge about the pathology of GI dysmotility in MNGIE, discuss potential mechanisms in relation to ICC loss/dysfunction, remark on the limited contribution of the current treatments, and propose intervention strategies to overcome ICC deficits. Finally, we address the advances and new research avenues offered by organoids and tissue engineering technologies, and propose schemes to implement to further our understanding of the GI pathology and utility in regenerative and personalized medicine in MNGIE.

Conclusion

Interstitial cells of Cajal play key roles in the physiology of the gastrointestinal motility. Evaluation of their status in the GI dysmotility related to MNGIE would be valuable for diagnosis of MNGIE. Understanding the underlying pathological and molecular mechanisms affecting ICC is an asset for the development of targeted prevention and treatment strategies for the GI dysmotility related to MNGIE.

Vascular Interstitial Cells in Retinal Arteriolar Annuli Are Altered During Hypertension

Purpose

It has been suggested that arteriolar annuli localized in retinal arterioles regulate retinal blood flow acting as sphincters. Here, the morphology and protein expression profile of arteriolar annuli have been analyzed under physiologic conditions in the retina of wild-type, β-actin-Egfp, and Nestin-gfp transgenic mice. Additionally, to study the effect of hypertension, the KAP transgenic mouse has been used.

Methods

Cellular architecture has been studied using digested whole mount retinas and transmission electron microscopy. The profile of protein expression has been analyzed on paraffin sections and whole mount retinas by immunofluorescence and histochemistry.

Results

The ultrastructural analysis of arteriolar annuli showed a different cell population found between endothelial and muscle cells that matched most of the morphologic criteria established to define interstitial Cajal cells. The profile of protein expression of these vascular interstitial cells (VICs) was similar to that of interstitial Cajal cells and different from the endothelial and smooth muscle cells, because they expressed β-actin, nestin, and CD44, but they did not express CD31 and α-SMA or scarcely express F-actin. Furthermore, VICs share with pericytes the expression of NG2 and platelet-derived growth factor receptor beta (PDGFR-β). The high expression of Ano1 and high activity of nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase observed in VICs was diminished during hypertensive retinopathy suggesting that these cells might play a role on the motility of arteriolar annuli and that this function is altered during hypertension.

Conclusions

A novel type of VICs has been described in the arteriolar annuli of mouse retina. Remarkably, these cells undergo important molecular modifications during hypertensive retinopathy and might thus be a therapeutic target against this disease.

Smooth Muscle Transcriptome Browser: offering genome-wide references and expression profiles of transcripts expressed in intestinal SMC, ICC, and PDGFRα+ cells

Transcriptome data on the quantitative numbers of transcriptional variants expressed in primary cells offer essential clues into specific cellular functions and biological processes. We have previously collected transcriptomes from primary smooth muscle cells (SMC), interstitial cells of Cajal (ICC), and PDGFRα+ cells (fibroblast-like cells) isolated from murine jejunal and colonic smooth muscle and/or mucosal tissues as well as transcriptomes from the associated tissues (jejunal smooth muscle, colonic smooth muscle, and colonic mucosa). In this study, we have built the Smooth Muscle Transcriptome Browser (SMTB), https://med.unr.edu/physio/transcriptome , a web-based, graphical user interface that offers genetic references and expression profiles of all transcripts expressed at both the cellular (SMC, ICC, and PDGFRα+ cells) and tissue level (smooth muscle and mucosal tissue). This browser brings new insights into the cellular and biological functions of the cell types in gastrointestinal smooth muscle biology.

Bioengineering functional smooth muscle with spontaneous rhythmic contraction in vitro

Oriented smooth muscle layers in the intestine contract rhythmically due to the action of interstitial cells of Cajal (ICC) that serve as pacemakers of the intestine. Disruption of ICC networks has been reported in various intestinal motility disorders, which limit the quality and expectancy of life. A significant challenge in intestinal smooth muscle engineering is the rapid loss of function in cultured ICC and smooth muscle cells (SMC). Here we demonstrate a novel approach to maintain the function of both ICC and SMC in vitro. Primary intestinal SMC mixtures cultured on feeder cells seeded electrospun poly(3-caprolactone) scaffolds exhibited rhythmic contractions with directionality for over 10 weeks in vitro. The simplicity of this system should allow for wide usage in research on intestinal motility disorders and tissue engineering, and may prove to be a versatile platform for generating other types of functional SMC in vitro.

Ursodeoxycholic acid protects interstitial Cajal-like cells in the gallbladder from undergoing apoptosis by inhibiting TNF-α expression

Hypomotility is a common symptom of gallstone disease, which is accompanied by a loss of interstitial Cajal-like cells (ICLCs) in the gallbladder. Ursodeoxycholic acid (UDCA) is widely used in treating gallstone disease, and has shown anti-apoptotic and anti-inflammatory effects apart from its ability to dissolve gallstones. In this study, we investigated the anti-apoptotic and anti-inflammatory effects of UDCA on ICLCs in guinea pigs with gallstones. Guinea pigs were fed a high-cholesterol diet for 8 weeks to induce the formation of gallstones. A group of animals was administered UDCA (50 mg·kg^-1·d^-1, ig) simultaneously. At the end of 8 weeks, the animals were euthanized with anesthesia, cholecystectomy was performed immediately and gallbladder was collected for further analysis. We showed that in the model group the contractility of gallbladder muscle strips in response to both acetylcholine (ACh) and CCK-8 was severely impaired, which was significantly improved by UDCA administration. Furthermore, UDCA administration significantly reduced the apoptotic ratio of ICLCs, based on the observation of co-localization imaging of apoptotic cells and c-kit-positive cells. Western blotting analysis and real-time PCR results revealed that the TNF-α/Caspase8/Caspase3 pathway was suppressed in the UDCA-treated animals, confirming the anti-apoptotic effect of UDCA in the gallbladder. The H&E staining showed that UDCA administration significantly attenuated inflammatory cell infiltration in the gallbladder wall. In conclusion, UDCA can protect ICLCs in the gallbladder from undergoing apoptosis by inhibiting the TNF-α/Caspase8/caspase3 pathway.

Uterine EMG activity in the non-pregnant sow during estrous cycle

BACKGROUND

Uterine myoactivity is crucial for successful reproductive performance of the sow. Spontaneous contractions of the uterus are strictly controlled and coordinated. Uterine electromyographic (EMG) activity undergoes hormonal regulation with rapid and long-term effects. What is more, interstitial Cajal-like Cells (ICLC) appear essential for smooth muscle contractility in the reproductive tract where they are suspected to be playing a major role in generating, coordinating, modulating and synchronizing slow triggering waves. The aim of this study was to investigate the myoelectrical activity of sow's uterus during estrus cycle.

RESULTS

Study was conducted on 10 Polish Landrace sows. Propagation mechanisms and their connection with the uterine EMG activity were considered in correlation with expression of c-kit, progesterone and oxytocin receptors of the non-pregnant sow. ICLC were labeled with antibody directed against c-kit receptor and visualized by confocal microscopy and scanning cytometer for positive cells percentage assessment. EMG signal was recorded directly from the myometrium with telemetry transmitters and electrodes located in different topographic regions of reproductive tracts. The stages of estrus cycle were determined by monitoring levels of luteinizing hormone, progesterone and estrogen with radioimmunoassays. Significant differences of the EMG signal parameters between diestrus and estrus and the correlations with density of labelled receptors were demonstrated. Moreover, the electrophysiological studies indicated that ICLC in the myometrium in the tip of uterine horn may participate in the regulation of slow waves duration and frequency.

CONCLUSIONS

The pattern of EMG signal propagation in the wall of the non-pregnant porcine uterus occurs in an orderly, bidirectional fashion and at distinctive speed, with no differences between diestrus and estrus.

Disruption of the pacemaker activity of interstitial cells of Cajal via nitric oxide contributes to postoperative ileus

BACKGROUND

Interstitial cells of Cajal (ICC) serve as intestinal pacemakers. Postoperative ileus (POI) is a gastrointestinal motility disorder that occurs following abdominal surgery, which is caused by inflammation-induced dysfunction of smooth muscles and enteric neurons. However, the participation of ICC in POI is not well understood. In this study, we investigated the functional changes of ICC in a mouse model of POI.

METHODS

Intestinal manipulation (IM) was performed to induce POI. At 24 h or 48 h after IM, the field potential of the intestinal tunica muscularis was investigated. Tissues were also examined by immunohistochemistry and electron microscopic analysis.

KEY RESULTS

Gastrointestinal transit was significantly decreased with intestinal tunica muscularis inflammation at 24 h after IM, which was ameliorated at 48 h after IM. The generation and propagation of pacemaker potentials were disrupted at 24 h after IM and recovered to the control level at 48 h after IM. ICC networks, detected by c-Kit immunoreactivity, were remarkably disrupted at 24 h after IM. Electron microscopic analysis revealed abnormal vacuoles in the ICC cytoplasm. Interestingly, the ICC networks recovered at 48 h after IM. Administration of aminoguanidine, an inducible nitric oxide synthase inhibitor, suppressed the disruption of ICC networks. Ileal smooth muscle tissue cultured in the presence of nitric oxide donor, showed disrupted ICC networks.

CONCLUSIONS AND INFERENCES

The generation and propagation of pacemaker potentials by ICC are disrupted via nitric oxide after IM, and this disruption may contribute to POI. When inflammation is ameliorated, ICC can recover their pacemaker function.

Investigation of autophagy and differentiation of myenteric interstitial cells of Cajal in the pathogenesis of gastric motility disorders in rats with functional dyspepsia

Interstitial cells of Cajal (ICC), especially myenteric interstitial cells of Cajal (ICC-MY), are key to gastrointestinal motility. However, their role in the pathogenesis of functional dyspepsia (FD) is unclear. Therefore, autophagy and differentiation of ICC-MY were investigated to elucidate the pathogenesis of gastric motility disorder in FD. FD model was induced by chronic stress via tail clamping in rats, which was assessed by the vital signs of rats, gastric emptying rate result, and histology. The ultrastructure of ICC-MY was examined using transmission electron microscope. In ICC-MY, changes in autophagic biomarkers (Beclin1 and LC3B) and differentiation biomarkers (c-kit and SCF) were evaluated with in situ hybridization, quantitative real time PCR, immunofluorescence, and Western blot, respectively. The FD model was successfully induced in rats, as evidenced by the abnormal vital signs (such as loss of appetite, liquid excreta, less activity, and slower weight gain), the decrease in gastric emptying rates, and little pathological change in gastric antrum tissue. Compared with the control group, FD caused increased organelle denaturation or reduction and increase in vacuolization. FD also promoted generation of autophagosomes in ICC-MY. Moreover, increased the expression of Beclin1 and LC3B, but decreased expression of c-kit and SCF. Excessive autophagy and abnormal differentiation of ICC-MY may contribute to the pathogenesis of gastric motility disorder in FD.

Development of interstitial cells of Cajal in the human digestive tract as the result of reciprocal induction of mesenchymal and neural crest cells

Neural crest cells (NCC) can migrate into different parts of the body and express their strong inductive potential. In addition, they are multipotent and are able to differentiate into various cell types with diverse functions. In the primitive gut, NCC induce differentiation of muscular structures and interstitial cells of Cajal (ICC), and they themselves differentiate into the elements of the enteric nervous system (ENS), neurons and glial cells. ICC develop by way of mesenchymal cell differentiation in the outer parts of the primitive gut wall around the myenteric plexus (MP) ganglia, with the exception of colon, where they appear simultaneously also at the submucosal border of the circular muscular layer around the submucosal plexus (SMP) ganglia. However, in a complex process of reciprocal induction of NCC and local mesenchyma, c‐kit positive precursors are the first to differentiate, representing probably the common precursors of ICC and smooth muscle cells (SMC). C‐kit positive precursors could represent a key impact factor regarding the final differentiation of NCC into neurons and glial cells with neurons subsequently excreting stem cell factor (SCF) and other signalling molecules. Under the impact of SCF, a portion of c‐kit positive precursors lying immediately around the ganglia differentiate into ICC, while the rest differentiate into SMC.

Surgical Pathology of Gastrointestinal Stromal Tumors: Practical Implications of Morphologic and Molecular Heterogeneity for Precision Medicine

Gastrointestinal stromal tumor (GIST), the most common mesenchymal neoplasm of the gastrointestinal tract, exhibits diverse histologic and clinical manifestations. With its putative origin in the gastrointestinal pacemaker cell of Cajal, GIST can arise in association with any portion of the tubular gastrointestinal tract. Morphologically, GISTs are classified as spindled or epithelioid, though each of these subtypes encompasses a broad spectrum of microscopic appearances, many of which mimic other histologic entities. Despite this morphologic ambiguity, the diagnosis of GIST is aided in many cases by immunohistochemical detection of KIT (CD117) or DOG1 expression. The natural history of GIST ranges from that of a tumor cured by surgical resection to that of a locally advanced or even widely metastatic, and ultimately fatal, disease. This clinicopathologic heterogeneity is paralleled by an underlying molecular diversity: the majority of GISTs are associated with spontaneous activating mutations in KIT, PDGFRA, or BRAF, while additional subsets are driven by genetic lesions-often inherited-of NF1 or components of the succinate dehydrogenase enzymatic complex. Specific gene mutations correlate with particular anatomic or morphologic characteristics and, in turn, with distinct clinical behaviors. Therefore, prognostication and treatment are increasingly dictated not only by morphologic clues, but also by accompanying molecular genetic features. In this review, we provide a comprehensive description of the heterogenous molecular underpinnings of GIST, including implications for the practicing pathologist with regard to morphologic identification, immunohistochemical diagnosis, and clinical management.

The Potential for Gut Organoid Derived Interstitial Cells of Cajal in Replacement Therapy

Effective digestion requires propagation of food along the entire length of the gastrointestinal tract. This process involves coordinated waves of peristalsis produced by enteric neural cell types, including different categories of interstitial cells of Cajal (ICC). Impaired food transport along the gastrointestinal tract, either too fast or too slow, causes a range of gut motility disorders that affect millions of people worldwide. Notably, loss of ICC has been shown to affect gut motility. Patients that suffer from gut motility disorders regularly experience diarrhoea and/or constipation, insomnia, anxiety, attention lapses, irritability, dizziness, and headaches that greatly affect both physical and mental health. Limited treatment options are available for these patients, due to the scarcity of human gut tissue for research and transplantation. Recent advances in stem cell technology suggest that large amounts of rudimentary, yet functional, human gut tissue can be generated in vitro for research applications. Intriguingly, these stem cell-derived gut organoids appear to contain functional ICC, although their frequency and functional properties are yet to be fully characterised. By reviewing methods of gut organoid generation, together with what is known of the molecular and functional characteristics of ICC, this article highlights short- and long-term goals that need to be overcome in order to develop ICC-based therapies for gut motility disorders.

Transcriptome analysis of PDGFRα+ cells identifies T-type Ca2+ channel CACNA1G as a new pathological marker for PDGFRα+ cell hyperplasia

Platelet-derived growth factor receptor alpha (PDGFRα)+ cells are distributed into distinct morphological groups within the serosal, muscular, and submucosal layers as well as the myenteric and deep muscular plexi. PDGFRα+ cells directly interact with interstitial cells of Cajal (ICC) and smooth muscle cells (SMC) in gastrointestinal smooth muscle tissue. These three cell types, SMC, ICC, and PDGFRα+ cells (SIP cells), form an electrical syncytium, which dynamically regulates gastrointestinal motility. We have previously reported the transcriptomes of SMC and ICC. To complete the SIP cell transcriptome project, we obtained transcriptome data from jejunal and colonic PDGFRα+ cells. The PDGFRα+ cell transcriptome data were added to the Smooth Muscle Genome Browser that we previously built for the genome-scale gene expression data of ICC and SMC. This browser provides a comprehensive reference for all transcripts expressed in SIP cells. By analyzing the transcriptomes, we have identified a unique set of PDGFRα+ cell signature genes, growth factors, transcription factors, epigenetic enzymes/regulators, receptors, protein kinases/phosphatases, and ion channels/transporters. We demonstrated that the low voltage-dependent T-type Ca2+ channel Cacna1g gene was particularly expressed in PDGFRα+ cells in the intestinal serosal layer in mice. Expression of this gene was significantly induced in the hyperplasic PDGFRα+ cells of obstructed small intestine in mice. This gene was also over-expressed in colorectal cancer, Crohn's disease, and diverticulitis in human patients. Taken together, our data suggest that Cacna1g exclusively expressed in serosal PDGFRα+ cells is a new pathological marker for gastrointestinal diseases.

Telocytes: New Players in Gallstone Disease

Cholesterol gallstone disease is highly prevalent in Western countries, particularly in women and some specific ethnic groups. The mechanisms behind the formation of gallstones are not clearly understood, but gallbladder dysmotility seems to be a key factor that triggers the precipitation of cholesterol microcrystals from supersaturated lithogenic bile.Given that newly described interstitial cells, telocytes, are present in the gallbladder and they are located in close vicinity of smooth muscle cell and neural fibers possibly interfering with gallbladder motility or contractility, authors are trying to summarize the current knowledge on the role of telocytes with respect to disturbed gallbladder function in gallstone disease.

Role of stem cell factor in the regulation of ICC proliferation and detrusor contraction in rats with an underactive bladder

Stem cell factor (SCF) is critical in regulating the proliferation, differentiation and function of the interstitial cells of Cajal (ICCs), which are closely associated with smooth muscle dysfunction. The present study aimed to examine the effect of SCF on ICC proliferation and detrusor contraction in rats with an underactive bladder. Sprague-Dawley rats were divided into four groups comprising control, control+SCF, detrusor underactivity (DU), and DU+SCF groups. The ICC count was determined using immunofluorescence; serum levels of SCF were determined using an enzyme-linked immunosorbent assay; mRNA and protein levels of c-kit and SCF in tissues were assessed using reverse transcription-quantitative polymerase chain reaction and western blot analyses, respectively. Detrusor contractility was determined using muscle strips, based on the contraction amplitude and frequency determined in each specimen. Significantly fewer ICCs were observed in the DU group, in addition to decreased expression levels of SCF and c-kit, compared with the control group. In addition, the detrusor contraction frequency and amplitude were markedly reduced. However, the administration of SCF significantly increased the number of ICCs, and the levels of SCF and c-kit in animals with DU, and resulted in markedly amplified detrusor contraction frequency and amplitude. Similarly, the number of ICCs and levels of SCF and c-kit were higher in the control+SCF group, compared with the control group. Overall, these findings suggested that exogenous SCF improved the organ dysfunction caused by reduced ICC number, providing a novel approach for organ repair.

Stem Cell Factor/Kit Signal Insufficiency Contributes to Hypoxia-Induced Intestinal Motility Dysfunctions in Neonatal Mice

BACKGROUND

Gastrointestinal (GI) motility disorders represent a group of problems that more constantly encountered in preterm infants. However, whether hypoxia exposure contributes to the GI dysfunctions is still unclear.

METHODS

Newborn mice were exposed to hypoxia (10%) from P1 to P7. Intestinal motilities were examined by a strain gauge transducer. The proliferation of ICCs was detected by using immunostaining for BrdU, Ki67, Kit, Ano1, and insulin-like growth factor 1 receptor (IGF-1R+). Smooth muscle cells and enteric neurons were revealed by immunostaining for α-SMA and NF200, respectively. Apoptosis was assessed by TUNEL assay. Kit signal pathway was examined by western blot and qPCR.

RESULTS

Intestinal motilities were found weakened significantly in the hypoxic small intestines as compared to controls on P8. Kit+ or Ano1+ interstitial cells of Cajal (ICCs) were found obviously decreased in the myenteric ICCs (ICC-MY) of neonatal mice after exposed to hypoxia. A large number of ICC progenitors (IGF-1R+) were found highly mitotic (BrdU+ Ki67+) to populate ICC during early postnatal development in the normoxic mice. We found the ICC proliferation was significantly inhibited upon hypoxia exposure, without increasing apoptosis (TUNEL+). We next identified that Kit phosphorylation was inhibited 3 days after hypoxia exposure. The inhibition of Kit signaling was largely due to decreased the expression of the ligand of Kit receptor, stem cell factor (SCF), in the intestinal walls. Exposure to imatinib, a Kit receptor inhibitor, for 3 days from P4 phenocopied the effect of hypoxia on the neonatal pups that resulted in inhibited intestinal motilities and decreased Kit+ ICC numbers.

CONCLUSION

All together, our findings indicate the SCF/Kit signaling insufficiency may contribute to the underdevelopment of ICCs and intestinal motility dysfunction upon hypoxia exposure. The decease in ICC density is likely due to the cell cycle arrest of ICC progenitor cells.

Transcriptome of interstitial cells of Cajal reveals unique and selective gene signatures

Transcriptome-scale data can reveal essential clues into understanding the underlying molecular mechanisms behind specific cellular functions and biological processes. Transcriptomics is a continually growing field of research utilized in biomarker discovery. The transcriptomic profile of interstitial cells of Cajal (ICC), which serve as slow-wave electrical pacemakers for gastrointestinal (GI) smooth muscle, has yet to be uncovered. Using copGFP-labeled ICC mice and flow cytometry, we isolated ICC populations from the murine small intestine and colon and obtained their transcriptomes. In analyzing the transcriptome, we identified a unique set of ICC-restricted markers including transcription factors, epigenetic enzymes/regulators, growth factors, receptors, protein kinases/phosphatases, and ion channels/transporters. This analysis provides new and unique insights into the cellular and biological functions of ICC in GI physiology. Additionally, we constructed an interactive ICC genome browser (http://med.unr.edu/physio/transcriptome) based on the UCSC genome database. To our knowledge, this is the first online resource that provides a comprehensive library of all known genetic transcripts expressed in primary ICC. Our genome browser offers a new perspective into the alternative expression of genes in ICC and provides a valuable reference for future functional studies.