Future therapies for Hirschsprung's disease

Literature review: enteric nervous system development, genetic and epigenetic regulation in the etiology of Hirschsprung's disease

Hirschsprung's disease (HSCR) is a developmental disorder of the enteric nervous system (ENS) derived from neural crest cells (NCCs), which affects their migration, proliferation, differentiation, or preservation in the digestive tract, resulting in aganglionosis in the distal intestine. The regulation of both NCCs and the surrounding environment involves various genes, signaling pathways, transcription factors, and morphogens. Therefore, changes in gene expression during the development of the ENS may contribute to the pathogenesis of HSCR.

This review discusses several mechanisms involved in the development of ENS, confirming that deviant genetic and epigenetic patterns, such as DNA methylation, histone modification, and microRNA (miRNA) regulation, can contribute to the development of neurocristopathy. Specifically, the epigenetic regulation of miRNA expression and its relationship to cellular interactions and gene activation through various major pathways in Hirschsprung's disease will be discussed.

Surgical Correction of Hirschsprung's Disease in Children Using the Soave-Boley Technique with Manual Colorectal Anastomosis

Introduction. Current trends in surgical treatment of Hirschsprung's disease are aimed at minimally invasive interventions. However, the experience of using Soave-Boley procedure in surgical treatment of Hirschsprung's disease in children of different ages is valuable in the arsenal of differentiated approach to the treatment of this pathology. The objective of the research was to evaluate the results of surgical correction of Hirschsprung's disease in children using the Soave-Boley technique with manual colorectal anastomosis. Materials and Methods. The analysis of surgical treatment of 1,187 children with different forms of Hirschsprung’s disease aged from birth to 18 years over the period 1980-2020 was conducted in the National Children's Specialized Hospital“ Okhmatdyt”. Surgical correction of Hirschsprung's disease using the Soave-Boley technique was performed in 597 children. Before surgery, 156 patients underwent the first stage of treatment that consisted in the creation of a protective colostomy; in 441 cases, this intervention was performed without an intestinal stoma; the benefits of the Soave-Boley technique were evaluated. Results. All the patients survived. In 15 (2.51%) out of 597 children, in the early postoperative period, there were observed: retrocolic hematoma (n = 2), retrocolic abscess (n = 7), anastomotic leak (n = 2), adhesive intestinal obstruction (n = 3), intussusception (n = 1). Fourteen (2.36%) patients developed surgical complications in the long-term period: residual aganglionosis (n = 9), anastomotic stenosis (n = 4) and coloptosis. Repeated Soave-Boley operation with manual colorectal anastomosis was successfully performed in 26 (4.362%) patients after primary correction of Hirschsprung's disease using different methods. Periodic episodes of fecal smearing in the remote period in 45 (7.53%) children were eliminated by conservative treatment. The success of this technique is confirmed by a much lower number of early (2.51%) and late (2.36%) postoperative surgical complications, as compared to those after using other methods of open surgical correction - 17.52% and 16.35%, respectively. Conclusions. Surgical correction of Hirschsprung's disease in children using the Soave-Boley technique with manual colorectal anastomosis allows better control over applying each suture, anatomical joining the edges of the bowel, and reducing trauma to the rectal mucosa, which ensures the high reliability of colorectal anastomosis; it is the most effective way of radical correcting Hirschsprung' s disease in children in an open way in one-stage or two-stage interventions, and this technique is the operation of choice for secondary surgical correction of Hirschsprung's disease.

Involvement of the lncRNA AFAP1-AS1/microRNA-195/E2F3 axis in proliferation and migration of enteric neural crest stem cells of Hirschsprung's disease

NEW FINDINGS

What is the central question of this study? Long non-coding RNAs (lncRNAs) are widely involved in the progression of Hirschsprung's disease (HSCR), but the role of actin filament associated protein 1 antisense RNA1 (AFAP1-AS1), an lncRNA, in HSCR has not been explored before. What is the main finding and its importance? Downregulation of AFAP1-AS1 blocks enteric neural crest stem cell proliferation, differentiation, migration and invasion and promotes the occurrence of HSCR via the miR-195/E2F3 axis, indicating thatAFAP1-AS might be a potential biomarker for HSCR patients.

ABSTRACT

Long non-coding RNAs (lncRNAs) are involved in several human disorders. Nevertheless, it remains unclear whether they are implicated in the phenotypes of enteric neural crest stem cells (ENCSCs) in Hirschsprung's disease (HSCR). Therefore, we designed this study to explore the pathogenicity of AFAP1-AS1 for HSCR. Microarray analysis and bioinformatic tools were used to screen out the differentially lncRNAs and microRNAs (miRNAs) in patients with HSCR. Small interference RNA transfection was applied to carry out functional experiments in ENCSCs. Cellular activities were detected by cell counting kit-8, 5-ethynyl-2'-deoxyuridine, Transwell assays and flow cytometry. Finally, rescue experiments were performed to examine the cofunction of AFAP1-AS1 and miR-195 and of miR-195 and E2F transcription factor 3 (E2F3). AFAP1-AS1 was reduced in HSCR patients. Meanwhile, knockdown of AFAP1-AS1 reduced the cell migratory and proliferative capacities and facilitated cell apoptosis along with G0/G1 phase arrest. E2F3 was diminished when miR-195 was upregulated, and AFAP1-AS1 inhibition reduced its ability to bind to miR-195. Altogether, AFAP1-AS1 silencing acts as an endogenous RNA by interacting with miR-195 to alter E2F3 expression, thus conferring repressive effects on ENCSC activity and promoting HSCR progression.

"Too much guts and not enough brains": (epi)genetic mechanisms and future therapies of Hirschsprung disease - a review

Hirschsprung disease is a neurocristopathy, characterized by aganglionosis in the distal bowel. It is caused by failure of the enteric nervous system progenitors to migrate, proliferate, and differentiate in the gut. Development of an enteric nervous system is a tightly regulated process. Both the neural crest cells and the surrounding environment are regulated by different genes, signaling pathways, and morphogens. For this process to be successful, the timing of gene expression is crucial. Hence, alterations in expression of genes specific for the enteric nervous system may contribute to the pathogenesis of Hirschsprung’s disease. Several epigenetic mechanisms contribute to regulate gene expression, such as modifications of DNA and RNA, histone modifications, and microRNAs. Here, we review the current knowledge of epigenetic and epitranscriptomic regulation in the development of the enteric nervous system and its potential significance for the pathogenesis of Hirschsprung’s disease. We also discuss possible future therapies and how targeting epigenetic and epitranscriptomic mechanisms may open new avenues for novel treatment.

Postnatal human enteric neuronal progenitors can migrate, differentiate, and proliferate in embryonic and postnatal aganglionic gut environments

BACKGROUND

Enteric neural stem/progenitor cells (ENSCs) offer an innovative approach to treating Hirschsprung disease (HSCR) and other enteric neuropathies. However, postnatal-derived human ENSCs have not been thoroughly characterized and their behavior in the embryonic and postnatal intestinal environment is unknown.

METHODS

ENSCs were isolated from the intestines of 25 patients undergoing bowel resection, including 7 children with HSCR. Neuronal differentiation and proliferation of ENSCs from submucosal and myenteric plexuses from patients with and without HSCR were characterized. ENSC migration and differentiation were studied following transplantation into embryonic chick neural crest, embryonic chick hindgut, and postnatal mouse aganglionic colon.

RESULTS

The proliferative and neurogenic potential of ENSCs from HSCR intestine is equivalent to that of non-HSCR controls. Similarly, no difference was observed between myenteric- and submucosal-derived ENSCs. Postnatal ENSCs transplanted to embryonic neural crest pathways and to aneural hindgut migrate normally and differentiate into appropriate neural crest-derived cell types. ENSCs in postnatal mouse aganglionic colon differentiate into neurons and glia both ex vivo and in vivo.

CONCLUSIONS

ENSCs isolated from the postnatal intestine of patients with and without HSCR can behave like embryonic neural crest-derived cells. These results support the feasibility of cell-based therapy for future treatment of neurointestinal disease.

Exposure to GDNF Enhances the Ability of Enteric Neural Progenitors to Generate an Enteric Nervous System

Cell therapy is a promising approach to generate an enteric nervous system (ENS) and treat enteric neuropathies. However, for translation to the clinic, it is highly likely that enteric neural progenitors will require manipulation prior to transplantation to enhance their ability to migrate and generate an ENS. In this study, we examine the effects of exposure to several factors on the ability of ENS progenitors, grown as enteric neurospheres, to migrate and generate an ENS. Exposure to glial-cell-line-derived neurotrophic factor (GDNF) resulted in a 14-fold increase in neurosphere volume and a 12-fold increase in cell number. Following co-culture with embryonic gut or transplantation into the colon of postnatal mice in vivo, cells derived from GDNF-treated neurospheres showed a 2-fold increase in the distance migrated compared with controls. Our data show that the ability of enteric neurospheres to generate an ENS can be enhanced by exposure to appropriate factors.

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Enteric neurospheres are likely to require manipulation for clinical applications

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Exposure to GDNF increased the size and cell number in enteric neurospheres

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GDNF-treated neurospheres showed enhanced migration after transplantation in vivo

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Manipulation of enteric neurospheres can enhance the generation of enteric neurons

Enteric nervous system stem cells associated with thickened extrinsic fibers in short segment aganglionic Hirschsprung's disease gut are absent in the total colonic and intestinal variants of disease

BACKGROUND/PURPOSE

Despite current treatments patients with Hirschsprung's disease (HSCR) suffer significant long-term morbidity. Therefore, there is increasing interest in adjunctive therapies, such as using enteric nervous system stem cells (ENSSC), isolated from typical aganglionic bowel. The source of these cells is unclear however it is hypothesized that they are present in the thickened nerve trunks in aganglionic short and long segment HSCR gut. These cells should therefore be absent in total colonic and pan intestinal HSCR where these thickened fibers are absent.

METHODS

Cells were isolated from samples of short segment HSCR gut (n=18) and total colonic and total intestinal HSCR gut (n=2). Acetylcholinesterase histochemistry confirmed the presence/absence of thickened nerve trunks. P75 immunofluorescence highlighted ENSSC at isolation and after 10days in culture in both groups.

RESULTS

ENSSC were not isolated or cultured from total colonic and total intestinal HSCR gut where thickened nerve trunks were absent. In contrast 10.0% (+/-1.9 SEM) of cells from short segment HSCR gut were ENSSC at isolation rising to 22.7% (+/-2.9 SEM) after 10days in culture.

CONCLUSIONS

These results associate ENSCC with thickened nerve trunks and also suggest that the aganglionic bowel segment in total colonic and intestinal HSCR cannot be used as a source of ENSCC for adjunctive therapy.

Isogenic enteric neural progenitor cells can replace missing neurons and glia in mice with Hirschsprung disease

BACKGROUND

Transplanting autologous patient-derived enteric neuronal stem/progenitor cells (ENSCs) is an innovative approach to replacing missing enteric neurons in patients with Hirschsprung disease (HSCR). Using autologous cells eliminates immunologic and ethical concerns raised by other cell sources. However, whether postnatal aganglionic bowel is permissive for transplanted ENSCs and whether ENSCs from HSCR patients can be successfully isolated, cultured, and transplanted in vivo remains unknown.

METHODS

ENSCs isolated from the ganglionic intestine of Ednrb(-/-) mice (HSCR-ENSCs) were characterized immunohistochemically and evaluated for their capacity to proliferate and differentiate in vitro. Fluorescently labeled ENSCs were co-cultured ex vivo with aganglionic Ednrb(-/-) colon. For in vivo transplantation, HSCR-ENSCs were labeled with lentivirus expressing green fluorescent protein (GFP) and implanted into aganglionic embryonic chick gut in ovo and postnatal aganglionic Ednrb(-/-) rectum in vivo.

KEY RESULTS

HSCR-ENSCs maintain normal capacity self-renewal and neuronal differentiation. Moreover, the Ednrb(-/-) aganglionic environment is permissive to engraftment by wild-type ENSCs ex vivo and supports migratrion and neuroglial differentiation of these cells following transplantation in vivo. Lentiviral GFP-labeled HSCR-ENSCs populated embryonic chick hindgut and postnatal colon of Ednrb(-/-) HSCR, with cells populating the intermuscular layer and forming enteric neurons and glia.

CONCLUSIONS & INFERENCES

ENSCs can be isolated and cultured from mice with HSCR, and transplanted into the aganglionic bowel of HSCR littermates to generate enteric neuronal networks. These results in an isogenic model establish the potential of using autologous-derived stem cells to treat HSCR and other intestinal neuropathies.

Transplantation of amniotic fluid-derived neural stem cells as a potential novel therapy for Hirschsprung's disease

BACKGROUND/PURPOSE

We have previously shown that embryonic enteric neural stem cells (NSCs) isolated from the intestine colonize aganglionic intestine upon transplantation, but posttransplantation cell survival limits efficacy. The aims of this study were to investigate whether transplantation of amniotic fluid (AF)-derived NSCs could improve survival of the engrafted cells and promote functional recovery of the diseased colon.

METHODS

AF cells were induced into NSCs with neurogenic medium, and further differentiated into neurons and glial cells. Ednrb knockout mice received an intestinal intramuscular injection of 20,000 AF-derived NSCs into the aganglionic colon. Engrafted cells were visualized and characterized by immunohistochemistry for GFP, neuronal, and glial cell markers. Colonic motility was quantified by colonic bead expulsion time.

RESULTS

AF-derived NSCs had increased expression levels of the NSC marker Nestin and the glial cell marker GFAP compared to enteric NSCs. Transplanted AF-derived NSCs had decreased apoptosis and increased survival compared to enteric NSCs. Colonic motility was significantly improved in Ednrb knockout mice transplanted with AF-derived NSCs, as demonstrated by significantly decreased colonic bead expulsion time.

CONCLUSION

AF-derived NSCs have enhanced survival upon transplantation into a defective enteric nervous system. Transplantation of AF-derived NSCs may represent a potential novel future therapy for the treatment of Hirschsprung's disease.

Building a second brain in the bowel

The enteric nervous system (ENS) is sometimes called the "second brain" because of the diversity of neuronal cell types and complex, integrated circuits that permit the ENS to autonomously regulate many processes in the bowel. Mechanisms supporting ENS development are intricate, with numerous proteins, small molecules, and nutrients that affect ENS morphogenesis and mature function. Damage to the ENS or developmental defects cause vomiting, abdominal pain, constipation, growth failure, and early death. Here, we review molecular mechanisms and cellular processes that govern ENS development, identify areas in which more investigation is needed, and discuss the clinical implications of new basic research.

Analysis of a parent-initiated social media campaign for Hirschsprung's disease

Background

Social media can be particularly useful for patients or families affected by rare conditions by allowing individuals to form online communities across the world.

Objective

Our aim in this study was to conduct a descriptive and quantitative analysis of the use of a social media community for Hirschsprung’s Disease (HD).

Methods

In July 2011, a mother of a child with HD launched the “Shit Happens” campaign. The campaign uses social media (blogs, Twitter, and Facebook) to engage other families affected by HD. Internet analytics including Google Analytics and Facebook Insights were used to evaluate the reach and responsiveness of this campaign.

Results

On the day the HD campaign was launched, 387 people viewed the blog “Roo’s Journey”. Blog views have now exceeded 5400 views from 37 countries. The Facebook page extends to 46 countries, has an average post reach of 298 users, 1414 “likes”, and an overall reach of 131,032 users. The campaign has 135 Twitter followers and 344 tweets at the time of writing. The most common question posted on the Facebook page is related to treatment for extreme diaper rash. Responsiveness assessment demonstrated that within 2 hours of posting, a question could receive 143 views and 20 responses, increasing to 30 responses after 5 hours.

Conclusions

Social media networks are well suited to discussion, support, and advocacy for health-related conditions and can be especially important in connecting families affected by rare conditions. The HD campaign demonstrates the reach and responsiveness of a community that primarily relies on social media to connect families affected by HD. Although responsive, this community is currently lacking consistent access to evidence-based guidance for their common concerns. We will explore innovative consumer-researcher partnerships to offer a solution in future research.

Enteric neural progenitors are more efficient than brain-derived progenitors at generating neurons in the colon

Gut motility disorders can result from an absent, damaged, or dysfunctional enteric nervous system (ENS). Cell therapy is an exciting prospect to treat these enteric neuropathies and restore gut motility. Previous studies have examined a variety of sources of stem/progenitor cells, but the ability of different sources of cells to generate enteric neurons has not been directly compared. It is important to identify the source of stem/progenitor cells that is best at colonizing the bowel and generating neurons following transplantation. The aim of this study was to compare the ability of central nervous system (CNS) progenitors and ENS progenitors to colonize the colon and differentiate into neurons. Genetically labeled CNS- and ENS-derived progenitors were cocultured with aneural explants of embryonic mouse colon for 1 or 2.5 wk to assess their migratory, proliferative, and differentiation capacities, and survival, in the embryonic gut environment. Both progenitor cell populations were transplanted in the postnatal colon of mice in vivo for 4 wk before they were analyzed for migration and differentiation using immunohistochemistry. ENS-derived progenitors migrated further than CNS-derived cells in both embryonic and postnatal gut environments. ENS-derived progenitors also gave rise to more neurons than their CNS-derived counterparts. Furthermore, neurons derived from ENS progenitors clustered together in ganglia, whereas CNS-derived neurons were mostly solitary. We conclude that, within the gut environment, ENS-derived progenitors show superior migration, proliferation, and neuronal differentiation compared with CNS progenitors.

Regulation of progenitor cell proliferation and neuronal differentiation in enteric nervous system neurospheres

Enteric nervous system (ENS) progenitor cells isolated from mouse and human bowel can be cultured in vitro as neurospheres which are aggregates of the proliferating progenitor cells, together with neurons and glial cells derived from them. To investigate the factors regulating progenitor cell proliferation and differentiation, we first characterised cell proliferation in mouse ENS neurospheres by pulse chase experiments using thymidine analogs. We demonstrate rapid and continuous cell proliferation near the neurosphere periphery, after which postmitotic cells move away from the periphery to become distributed throughout the neurosphere. While many proliferating cells expressed glial markers, expression of the neuronal markers β-tubulin III (Tuj1) and nitric oxide synthase was detected in increasing numbers of post-mitotic cells after a delay of several days. Treatment of both mouse and human neurospheres with the γ-secretase inhibitor N-[N-(3,5-Difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT) reduced expression of the transcription factors Hes1 and Hes5, demonstrating inhibition of Notch signaling. DAPT treatment also inhibited progenitor cell proliferation and increased the numbers of differentiating neurons expressing Tuj1 and nitric oxide synthase. To confirm that the cellular effects of DAPT treatment were due to inhibition of Notch signaling, siRNA knockdown of RBPjκ, a key component of the canonical Notch signaling pathway, was demonstrated both to reduce proliferation and to increase neuronal differentiation in neurosphere cells. These observations indicate that Notch signaling promotes progenitor cell proliferation and inhibits neuronal differentiation in ENS neurospheres.