The microenvironment in the Hirschsprung's disease gut supports myenteric plexus growth

Cutting-edge regenerative therapy for Hirschsprung disease and its allied disorders

Hirschsprung disease (HSCR) and its associated disorders (AD-HSCR) often result in severe hypoperistalsis caused by enteric neuropathy, mesenchymopathy, and myopathy. Notably, HSCR involving the small intestine, isolated hypoganglionosis, chronic idiopathic intestinal pseudo-obstruction, and megacystis-microcolon-intestinal hypoperistalsis syndrome carry a poor prognosis. Ultimately, small-bowel transplantation (SBTx) is necessary for refractory cases, but it is highly invasive and outcomes are less than optimal, despite advances in surgical techniques and management. Thus, regenerative therapy has come to light as a potential form of treatment involving regeneration of the enteric nervous system, mesenchyme, and smooth muscle in affected areas. We review the cutting-edge regenerative therapeutic approaches for managing HSCR and AD-HSCR, including the use of enteric nervous system progenitor cells, embryonic stem cells, induced pluripotent stem cells, and mesenchymal stem cells as cell sources, the recipient intestine's microenvironment, and transplantation methods. Perspectives on the future of these treatments are also discussed.

Establishment and identification of an animal model of Hirschsprung disease in suckling mice

BACKGROUND

Hirschsprung disease (HSCR) is a congenital intestinal malformation. Previous HSCR animal model needs invasive operation on adult animal. The aim of this study is to establish an early-onset animal model which is consistent with the clinical manifestation of HSCR patients.

METHODS

The neonatal mice were randomly divided into the benzalkonium chloride (BAC) group, treated with BAC via enema, and the control group, treated with saline. Weight changes, excretion time of carmine, CT scan, hematoxylin-eosin staining and immunofluorescence staining were used to evaluate the effect of the model. Differentially expressed genes (DEGs) in the HSCR mice were analyzed by using DAVID 6.8 database and compared with DEGs from HSCR patients.

RESULTS

The weight of mice was lower and the excretion time of carmine was longer in the BAC group. Moreover, distal colon stenosis and proximal colon enlargement appeared in the BAC group. Neurons in the distal colon decreased significantly after 4 weeks of BAC treatment and almost disappeared completely after 12 weeks. Transcriptome profiling of the mouse model and HSCR patients is similar in terms of altered gene expression.

CONCLUSIONS

An economical and reliable HSCR animal model which has similar clinical characteristics to HSCR patients was successfully established.

IMPACT

The animal model of Hirschsprung disease was first established in BALB/c mice. This model is an animal model of early-onset HSCR that is easy to operate and consistent with clinical manifestations. Transcriptome profiling of the mouse model and HSCR patients is similar in terms of altered gene expression.

Differentiation of enteric neural crest cells transplanted from SOX10-Venus mouse embryonic stem cells into the gut of the endothelin receptor B null mouse model

PURPOSE

Failure of enteric neural crest-derived cells (ENCCs) to correctly colonize the embryonic gut results in Hirschsprung's disease (HD). Embryonic stem cells (ESCs) have the potential to differentiate into all tissue-specific cells and lineages, including ENCCs. We investigated the cellular differentiation of ESCs from Sox10-Venus ⁺ mice into both control and endothelin receptor-B knockout (Ednrb KO) mouse gut to assess each region.

METHODS

We established ESCs from Sox10-Venus ⁺ mice. These cells were cultured for 2 days, then selected and co-cultured with either a dissociated control or Sox10-Venus ^- Ednrb KO mouse gut (both small intestine and colon) on embryonic day (E) 13.5. Four days later, cells were immunolabeled for Tuj1 and visualized using confocal microscopy.

RESULTS

Confocal microscopy revealed that transplanted Sox10-Venu ⁺ cells from ESCs migrated extensively within the host gut. Moreover, Tuj1-positive neurites were detected in the transplanted ESCs. Tuj1 expression was significantly decreased in aganglionic HD colon compared to controls (p < 0.05) and the HD small intestine (p < 0.05).

CONCLUSIONS

This study demonstrated that an appropriate host environment is crucial for normal and complete colonization of the gut. Further investigations are required to confirm whether modifying this environment can improve the results of this model.

In vitro investigation of the differentiation of enteric neural crest-derived cells following transplantation of aganglionic gut in a mouse model

PURPOSE

Cell therapy is a promising approach to treat enteric neuropathies such as Hirschsprung disease (HD). Recent studies have reported that enteric neurons derived from stem cells (ENCCs) can be grafted into the HD colon. Thus, we investigated the migration and generation of enteric neurospheres from SOX10-VENUS⁺ mice after transplantation into control or Ednrb KO mice, which are a model of HD.

METHODS

Single-cell suspensions were isolated from the fetal guts of SOX10-VENUS⁺ mice E13.5 and dissociated. These cells were cultured for 7 days under non-adherent conditions to generate neurospheres, which were co-cultured with dissociated control or SOX10-VENUS^- Ednrb KO mouse gut on E13.5. 4 days later, these cells were fixed and the expression of the neuronal marker, Tuj1, was evaluated.

RESULTS

Transplanted neurospheres had undergone abundant neuronal migration and differentiation of ENCCs in the control gut compared with the HD gut. The average length and intersections were significantly decreased in HD colon compared with controls (p < 0.05), and a similar pattern was observed in the HD small intestine (p < 0.05).

CONCLUSIONS

We demonstrated that transplanted ENCCs did not differentiate properly in HD gut. These results highlight the importance of the neuronal environment in the recipient gut for enteric nervous system development.

Human skin-derived precursor cells xenografted in aganglionic bowel

PURPOSE

One in 5000 newborns is diagnosed with Hirschsprung disease each year in the United States. The potential of employing neural crest stem cells to restore the enteric nervous system has been investigated. Skin-derived precursor cells (SKPs) are multipotent progenitor cells that can differentiate into neurons and gliocytes in vitro and generate enteric ganglion-like structures in rodents. Here we examined the behavior of human SKPs (hSKPs) after their transplantation into a large animal model of colonic aganglionosis.

METHODS

Juvenile minipigs underwent a chemical denervation of the colon to establish an aganglionosis model. The hSKPs were generated from human foreskin and were cultured in neuroglial-selective medium. Cells were labeled with a fluorescent dye and were injected into the porcine aganglionic colon. After one week, transplanted hSKPs were assessed by immunofluorescence for markers of multipotency and neuroglial differentiation.

RESULTS

In culture, hSKPs expressed nestin and S100b indicative of neuroglial precursors. After xenografting in pigs, hSKPs were identified in the myenteric and submucosal plexuses of the colons. The hSKPs expressed nestin and early neuroglial differentiation markers.

CONCLUSIONS

Human SKPs transplanted into aganglionic colon demonstrated immunophenotypes of neuroglial progenitors, suggesting their potential use for Hirschsprung disease.

Inhibition of ROCK signaling pathway accelerates enteric neural crest cell-based therapy after transplantation in a rat hypoganglionic model

BACKGROUND

Hirschsprung's disease (HSCR) is a congenital gastrointestinal disorder, characterized by enteric ganglia absence in part or entire of the colon, due to abnormal colonization and migration of enteric neural crest cells (ENCCs) during development. Currently, besides surgery which is the main therapy for HSCR, the potential of stem cell-based transplantation was investigated as an alternative option. Although promising, it has limitations, including poor survival, differentiation, and migration of the grafted cells. We hypothesized that modulation of extracellular factors during transplantation could promote ENCCs proliferation and migration, leading to increased transplantation efficiency. Considering that the RhoA/ROCK pathway is highly involved in cytoskeletal dynamics and neurite growth, our study explored the effect of inhibition of this pathway to improve the success of ENCCs transplantation.

METHODS

Enteric neural crest cells were isolated from rat embryos and labeled with a GFP-tag. Cell viability, apoptosis, differentiation, and migration assays were performed with and without RhoA/ROCK inhibition. Labeled ENCCs were transplanted into the muscle layer of an induced hypoganglionic rat model followed by intraperitoneal injections of ROCK inhibitor. The transplanted segments were collected 3 weeks after for histological analysis.

KEY RESULTS

Our results showed that inhibition of ROCK increased viable cell number, differentiation, and migration of ENCCs in vitro. Moreover, transplantation of labeled ENCCs into the hypoganglionic model showed enhanced distribution of grafted ENCCs, upon treatment with ROCK inhibitor.

CONCLUSIONS AND INFERENCES

ROCK inhibitors influence ENCCs growth and migration in vitro and in vivo, and should be considered to improve the efficiency of ENCCs transplantation.

Autologous Transplantation of Skin-Derived Precursor Cells in a Porcine Model

BACKGROUND

Hirschprung's disease is characterized by aganglionic bowel and often requires surgical resection. Cell-based therapies have been investigated as potential alternatives to restore functioning neurons. Skin-derived precursor cells (SKPs) differentiate into neural and glial cells in vitro and generate ganglion-like structures in rodents. In this report, we aimed to translate this approach into a large animal model of aganglionosis using autologous transplantation of SKPs.

METHODS

Juvenile pigs underwent skin procurement from the shoulder and simultaneous chemical denervation of an isolated colonic segment. Skin cells were cultured in neuroglial-selective medium and labeled with fluorescent dye for later identification. The cultured SKPs were then injected into the aganglionic segments of colon, and the specimens were retrieved within seven days after transplantation. SKPs in vitro and in vivo were assessed with histologic samples for various immunofluorescent markers of multipotency and differentiation. SKPs from the time of harvest were compared to those at the time of injection using PCR.

RESULTS

Prior to transplantation, 72% of SKPs stained positive for nestin and S100b, markers of neural and glial precursor cells of neural crest origin, respectively. Markers of differentiated neurons and gliocytes, TUJ1 and GFAP, were detected in 47% of cultured SKPs. After transplantation, SKPs were identified in both myenteric and submucosal plexuses of the treated colon. Nestin co-expression was detected in the SKPs within the aganglionic colon in vivo. Injected SKPs appeared to migrate and express early neuroglial differentiation markers.

CONCLUSIONS

Autologous SKPs implanted into aganglionic bowel demonstrated immunophenotypes of neuroglial progenitors. Our results suggest that autologous SKPs may be potentially useful for cell-based therapy for patients with enteric nervous system disorders.

TYPE OF STUDY

Basic science.

Apoptotic neuron-secreted HN12 inhibits cell apoptosis in Hirschsprung's disease

Perturbation in apoptosis can lead to Hirschsprung's disease (HSCR), which is a genetic disorder of neural crest development. It is believed that long noncoding RNAs (lncRNAs) play a role in the progression of HSCR. This study shows that apoptotic neurons can suppress apoptosis of nonapoptotic cells by secreting exosomes that contain high levels of HN12 lncRNA. Elevated exogenous HN12 in nonapoptotic cells effectively inhibited cell apoptosis by maintaining the function of mitochondria, including the production of ATP and the release of cytochrome C. These results demonstrate that secreted lncRNAs may serve as signaling molecules mediating intercellular communication in HSCR. In addition, high HN12 levels in the circulation worked as a biomarker for predicting HSCR, providing a potential, novel, noninvasive diagnostic approach for early screening of HSCR.

A population-based, complete follow-up of 146 consecutive patients after transanal mucosectomy for Hirschsprung disease

OBJECTIVE

The objective of the study is to define the population-based bowel functional outcomes and enterocolitis following transanal endorectal pull-through (TEPT) in patients with Hirschsprung disease (HD) treated at our institution between 1986 and 2011.

METHODS

146 consecutive patients who had undergone primary surgical treatment for HD were included. The median follow-up time was 15 (3-33) years. The clinical details and prevalence of enterocolitis were evaluated in all patients, and bowel function in patients >3 years of age with functional intestino-anal continuity.

RESULTS

No patients were lost to follow-up. Overall survival was 98%. The level of disease was rectosigmoid in 83%, long segment in 7%, total colonic in 4%, and extending up to the small bowel in 6%. 29% had an associated syndrome. 22% had a preoperative stoma. Operations included TEPT (89%), proctocolectomy with ileoanal anastomosis in 9%, and 3% had a permanent endostomy owing to small intestinal aganglionosis. One patient underwent intestinal transplantation. At the latest follow-up, 42% had occasional soiling, 12% had frequent soiling and 46% had no soiling. Constipation occurred in 9%. An associated syndrome was the only predictor for soiling or constipation (OR 4.3, 95% CI 1.5-12). 44% developed recurrent postoperative enterocolitis, which was predicted by extended aganglionosis (OR 6.9, 95% CI 2.4-20) and syndromatic disease (OR 2.4, 95% CI 1.2-5.0).

CONCLUSION

The major functional sequelae following TEPT were recurrent enterocolitis and fecal soiling, which was mostly occasional. An associated syndrome was a predictor of a reduced bowel functional outcome, and alongside extended aganglionosis were significant risk factors for recurrent postoperative enterocolitis.

Stem cell therapy for GI neuromuscular disorders

The enteric nervous system is the intrinsic innervation of the gut. Several neuromuscular disorders affect the neurons and glia of the enteric nervous system adversely, resulting in disruptions in gastrointestinal motility and function. Pharmacological interventions to remedy gastrointestinal function do not address the underlying cause of dysmotility arising from lost, absent, or damaged enteric neuroglial circuitry. Cell-based therapies have gained traction in the past decade, following the discovery of several adult stem cell niches in the human body. Adult neural stem cells can be isolated from the postnatal and adult intestine using minimally invasive biopsies. These stem cells retain the ability to differentiate into several functional classes of enteric neurons and enteric glia. Upon identification of these cells, several groups have also established that transplantation of these cells into aganglionic or dysganglionic intestine rescues gastrointestinal motility and function. This chapter highlights key studies performed in the field of stem cell transplantation therapies that are targeted towards the remedy of gastrointestinal motility and function.

Transplanted skin-derived precursor stem cells generate enteric ganglion-like structures in vivo

INTRODUCTION

Hirschsprung's disease is characterized by a developmental arrest of neural crest cell migration, causing distal aganglionosis. Transplanted cells derived from the neural crest may regenerate enteric ganglia in this condition. We investigated the potential of skin-derived precursor cells (SKPs) to engraft and to differentiate into enteric ganglia in aganglionic rat intestine in vivo.

METHODS

Adult Lewis rat jejunal segments were separated from intestinal continuity and treated with benzalkonium chloride to induce aganglionosis. Ganglia were identified via immunohistochemical stains for S100 and β-III tubulin (TUJ1). SKPs were procured from neonatal Lewis rats expressing enhanced green fluorescent protein (GFP) and cultured in neuroglial-selective media. SKP cell line expansion was quantified, and immunophenotypes were assessed by immunocytochemistry. Aganglionic segments underwent SKP transplantation 21-79days after benzalkonium chloride treatment. The presence of GFP+cells, mature neurons, and mature glia was evaluated at posttransplant days 1, 6, and 9.

RESULTS

Benzalkonium chloride-induced aganglionosis persisted for at least 85days. Prior to differentiation, SKPs expressed S100, denoting neural crest lineage, and nestin, a marker of neuronal precursors. Differentiated SKPs in vitro expressed GFAP, a marker of glial differentiation, as well as TUJ1 and several enteric neurotransmitters. After transplantation, GFP+structures resembling ganglia were identified between longitudinal and circular smooth muscle layers.

CONCLUSION

SKPs are capable of engraftment, migration, and differentiation within aganglionic rodent intestine in vivo. Differentiated SKPs generate structures that resemble enteric ganglia. Our observations suggest that SKPs represent a potential gangliogenic therapeutic agent for Hirschsprung's disease.

The influence of extracellular matrix composition on the differentiation of neuronal subtypes in tissue engineered innervated intestinal smooth muscle sheets

Differentiation of enteric neural stem cells into several appropriate neural phenotypes is crucial while considering transplantation as a cellular therapy to treat enteric neuropathies. We describe the formation of tissue engineered innervated sheets, where intestinal smooth muscle and enteric neuronal progenitor cells are brought into close association in extracellular matrix (ECM) based microenvironments. Uniaxial alignment of constituent smooth muscle cells was achieved by substrate microtopography. The smooth muscle component of the tissue engineered sheets maintained a contractile phenotype irrespective of the ECM composition, and generated equivalent contractions in response to potassium chloride stimulation, similar to native intestinal tissue. We provided enteric neuronal progenitor cells with permissive ECM-based compositional and viscoelastic cues to generate excitatory and inhibitory neuronal subtypes. In the presence of the smooth muscle cells, the enteric neuronal progenitor cells differentiated to functionally innervate the smooth muscle. The differentiation of specific neuronal subtypes was influenced by the ECM microenvironment, namely combinations of collagen I, collagen IV, laminin and/or heparan sulfate. The physiology of differentiated neurons within tissue engineered sheets was evaluated. Sheets with composite collagen and laminin had the most similar patterns of Acetylcholine-induced contraction to native intestinal tissue, corresponding to an increased protein expression of choline acetyltransferase. An enriched nitrergic neuronal population, evidenced by an increased expression of neuronal nitric oxide synthase, was obtained in tissue engineered sheets that included collagen IV. These sheets had a significantly increased magnitude of electrical field stimulated relaxation, sensitive maximally to nitric oxide synthase inhibition. Tissue engineered sheets containing laminin and/or heparan sulfate had a balanced expression of contractile and relaxant motor neurons. Our studies demonstrated that neuronal subtype was modulated by varying ECM composition. This observation could be utilized to derive enriched populations of specific enteric neurons in vitro prior to transplantation.

Neural stem cell therapies for enteric nervous system disorders

The enteric nervous system is vulnerable to a range of congenital and acquired disorders that disrupt the function of its neurons or lead to their loss. The resulting enteric neuropathies are some of the most challenging clinical conditions to manage. Neural stem cells offer the prospect of a cure given their potential ability to replenish missing or dysfunctional neurons. This article discusses diseases that might be targets for stem cell therapies and the barriers that could limit treatment application. We explore various sources of stem cells and the proof of concept for their use. The critical steps that remain to be addressed before these therapies can be used in patients are also discussed. Key milestones include the harvesting of neural stem cells from the human gut and the latest in vivo transplantation studies in animals. The tremendous progress in the field has brought experimental studies exploring the potential of stem cell therapies for the management of enteric neuropathies to the cusp of clinical application.

Maintenance of the enteric stem cell niche by bacterial lipopolysaccharides? Evidence and perspectives

The enteric nervous system (ENS) has to respond to continuously changing microenvironmental challenges within the gut and is therefore dependent on a neural stem cell niche to keep the ENS functional throughout life. In this study, we hypothesize that this stem cell niche is also affected during inflammation and therefore investigated lipopolysaccharides (LPS) effects on enteric neural stem/progenitor cells (NSPCs). NSPCs were derived from the ENS and cultured under the influence of different LPS concentrations. LPS effects upon proliferation and differentiation of enteric NSPC cultures were assessed using immunochemistry, flow cytometry, western blot, Multiplex ELISA and real-time PCR. LPS enhances the proliferation of enteric NSPCs in a dose-dependent manner. It delays and modifies the differentiation of these cells. The expression of the LPS receptor toll-like receptor 4 on NSPCs could be demonstrated. Moreover, LPS induces the secretion of several cytokines. Flow cytometry data gives evidence for individual subgroups within the NSPC population. ENS-derived NSPCs respond to LPS in maintaining at least partially their stem cell character. In the case of inflammatory disease or trauma where the liberation and exposure to LPS will be increased, the expansion of NSPCs could be a first step towards regeneration of the ENS. The reduced and altered differentiation, as well as the induction of cytokine signalling, demonstrates that the stem cell niche may take part in the LPS-transmitted inflammatory processes in a direct and defined way.

Granulocyte-colony stimulating factor: a new player for the enteric nervous system

The enteric nervous system (ENS) controls and modulates gut motility and responds to food intake and to internal and external stimuli such as toxins or inflammation. Its plasticity is maintained throughout life by neural progenitor cells within the enteric stem cell niche. Granulocyte-colony stimulating factor (G-CSF) is known to act not only on cells of the immune system but also on neurons and neural progenitors in the central nervous system (CNS). Here, we demonstrate, for the first time, that G-CSF receptor is present on enteric neurons and progenitors and that G-CSF plays a role in the expansion and differentiation of enteric neural progenitor cells. Cultured mouse ENS-neurospheres show increased expansion with increased G-CSF concentrations, in contrast to CNS-derived spheres. In cultures from differentiated ENS- and CNS-neurospheres, neurite outgrowth density is enhanced depending on the amount of G-CSF in the culture. G-CSF might be an important factor in the regeneration and differentiation of the ENS and might be a useful tool for the investigation and treatment of ENS disorders.

Expression and function of the Transforming Growth Factor-b system in the human and rat enteric nervous system

BACKGROUND

Transforming growth factor-betas (TGF-bs) are pleiotropic growth factors exerting neurotrophic functions upon various neuronal populations of the central nervous system. In contrast, the role of TGF-b isoforms in the enteric nervous system (ENS) is largely unknown. We therefore analyzed the gene expression pattern of the TGF-b system in the human colon and in rat myenteric plexus, and smooth muscle cell cultures and determined the effect of TGF-b isoforms on neuronal differentiation.

METHODS

Human colonic samples as well as cultured rat myenteric plexus, and smooth muscle cells were assessed for mRNA expression levels of the TGF-b system (TGF-b1-3, TbR-1-3) by qPCR. The colonic wall was separated into mucosa and tunica muscularis and enteric ganglia were isolated by laser microdissection (LMD) to allow site-specific gene expression analysis. Effects of TGF-b isoforms on neurite outgrowth and branching pattern of cultured myenteric neurons were monitored.

KEY RESULTS

mRNA expression of the TGF-b system was detected in all compartments of the human colonic wall as well as in LMD-isolated myenteric ganglia. Cultured myenteric neurons and smooth muscle cells of rat intestine also showed mRNA expression of all ligands and receptors. Transforming growth factor-b2 treatment increased neurite length and branching pattern in cultured myenteric neurons.

CONCLUSIONS & INFERENCES

The TGF-b system is abundantly expressed in the human and rat ENS arguing for an auto-/paracrine function of this system on enteric neurons. Transforming growth factor-b2 promotes neuronal differentiation and plasticity characterizing this molecule as a relevant neurotrophic factor for the ENS.

Recent achievements in stem cell therapy for pediatric gastrointestinal tract disease

The field of stem cell research has been rapidly expanding. Although the clinical usefulness of research remains to be ascertained through human trials, the use of stem cells as a therapeutic option for currently disabling diseases holds fascinating potential. Many pediatric gastrointestinal tract diseases have defect in enterocytes, enteric nervous system cells, smooth muscles, and interstitial cells of Cajal. Various kinds of therapeutic trials using stem cells could be applied to these diseases. This review article focuses on the recent achievements in stem cell applications for pediatric gastrointestinal tract diseases.