The enteric neural crest progressively loses capacity to form enteric nervous system

Updates and Challenges in ENS Cell Therapy for the Treatment of Neurointestinal Diseases

Neurointestinal diseases represent a significant challenge in clinical management with current palliative approaches failing to overcome disease and treatment-related morbidity. The recent progress with cell therapy to restore missing or defective components of the gut neuromusculature offers new hope for potential cures. This review discusses the progress that has been made in the sourcing of putative stem cells and the studies into their biology and therapeutic potential. We also explore some of the practical challenges that must be overcome before cell-based therapies can be applied in the clinical setting. Although a number of obstacles remain, the rapid advances made in the enteric neural stem cell field suggest that such therapies are on the near horizon.

hPSC-derived sacral neural crest enables rescue in a severe model of Hirschsprung's disease

The enteric nervous system (ENS) is derived from both the vagal and sacral component of the neural crest (NC). Here, we present the derivation of sacral ENS precursors from human PSCs via timed exposure to FGF, WNT, and GDF11, which enables posterior patterning and transition from posterior trunk to sacral NC identity, respectively. Using a SOX2::H2B-tdTomato/T::H2B-GFP dual reporter hPSC line, we demonstrate that both trunk and sacral NC emerge from a double-positive neuro-mesodermal progenitor (NMP). Vagal and sacral NC precursors yield distinct neuronal subtypes and migratory behaviors in vitro and in vivo. Remarkably, xenografting of both vagal and sacral NC lineages is required to rescue a mouse model of total aganglionosis, suggesting opportunities in the treatment of severe forms of Hirschsprung's disease.

Opportunities for novel diagnostic and cell-based therapies for Hirschsprung disease

Despite significant progress in our understanding of the etiology and pathophysiology of Hirschsprung disease (HSCR), early and accurate diagnosis and operative management can be challenging. Moreover, long-term morbidity following surgery, including fecal incontinence, constipation, and Hirschsprung-associated enterocolitis (HAEC), remains problematic. Recent advances applying state-of-the art imaging for visualization of the enteric nervous system and utilizing neuronal stem cells to replace the missing enteric neurons and glial cells offer the possibility of a promising new future for patients with HSCR. In this review, we summarize recent research advances that may one day offer novel approaches for the diagnosis and management of this disease.

Dynamic integration of enteric neural stem cells in ex vivo organotypic colon cultures

Enteric neural stem cells (ENSC) have been identified as a possible treatment for enteric neuropathies. After in vivo transplantation, ENSC and their derivatives have been shown to engraft within colonic tissue, migrate and populate endogenous ganglia, and functionally integrate with the enteric nervous system. However, the mechanisms underlying the integration of donor ENSC, in recipient tissues, remain unclear. Therefore, we aimed to examine ENSC integration using an adapted ex vivo organotypic culture system. Donor ENSC were obtained from Wnt1^cre/+;R26R^YFP/YFP mice allowing specific labelling, selection and fate-mapping of cells. YFP⁺ neurospheres were transplanted to C57BL6/J (6–8-week-old) colonic tissue and maintained in organotypic culture for up to 21 days. We analysed and quantified donor cell integration within recipient tissues at 7, 14 and 21 days, along with assessing the structural and molecular consequences of ENSC integration. We found that organotypically cultured tissues were well preserved up to 21-days in ex vivo culture, which allowed for assessment of donor cell integration after transplantation. Donor ENSC-derived cells integrated across the colonic wall in a dynamic fashion, across a three-week period. Following transplantation, donor cells displayed two integrative patterns; longitudinal migration and medial invasion which allowed donor cells to populate colonic tissue. Moreover, significant remodelling of the intestinal ECM and musculature occurred upon transplantation, to facilitate donor cell integration within endogenous enteric ganglia. These results provide critical evidence on the timescale and mechanisms, which regulate donor ENSC integration, within recipient gut tissue, which are important considerations in the future clinical translation of stem cell therapies for enteric disease.

Microstructure of the nerve plexus of the muscular membrane of the gut of domestic ducks (Anas platyrhynchos domesticus) of different ages

As evidenced by the publications of recent years, contrary to the existing dogma about the immutability of the state of the enteric nervous system during the postnatal period of ontogenesis, the population of intestinal neurons is a dynamic formation, decreasing with age and changing due to the action of environmental factors. The current article presents the results of study of the microscopic structure of the nerve plexus of the muscular membrane of the enteric nervous system of domestic ducks (Anas platyrhynchos domesticus) of the black white–breasted breed, of nine age groups of 1–365 days of age. The topography, number, area of nerve nodes, as well as the density of neurons in them were determined on transverse sections of the duodenum, jejunum, ileum, caecum and rectum. For the purpose of a generalized assessment of the morphofunctional state of the nerve plexuses, two parameters were determined: the average age indicator of the gut and intestines. The average age indicator of a certain structure of each intestine was determined as the arithmetical average of its nine age indicators. The average age indicator of a certain gut structure was determined as the arithmetic average of the average age indicator of the structure of all five intestines. It has been established that the nerve plexus of the muscular membrane (myenteric, plexus Auerbachi) of the gut of domestic ducks, in contrast to mammals, is not located between the layers of the muscular membrane, but in its outer layer. On a transverse section of the gut wall, the myenteric ganglia and cords that connect have a predominantly elliptical shape. Despite a significant increase with age in the diameter and thickness of the gut wall, the total number of myenteric ganglia changed little, increasing or decreasing with varying degrees of reliability relative to the previous age. In the gut of ducks, during the first year of the postnatal period of ontogenesis, the smallest number of myenteric ganglia was found in the cecum, and the largest – in the ileum. The general pattern of the dynamics of the size of the myenteric ganglia of the gut of ducks was an increase in their area with age. Moreover, this indicator reached the greatest value at different ages of ducks: at 30 days of age in the ileum and cecum, at 180 days of age – in the rectum and at 365 days of age – in the duodenum. The smallest area of the myenteric ganglia was found in the jejunum, and the largest – in the duodenum and ileum. The smallest number of neurons in the ganglion was found in the cecum, and the largest – in the rectum, the lowest density of neurons in the ganglion was found in the cecum, and the largest – in the jejunum. The general quantitative pattern of neurons in the ganglion was the decrease in their density with age. Changes in the morphometric parameters of the ganglia of the nerve plexus of the muscular membrane of the ducks’ gut indicate the plasticity of the enteric nervous system, its ability to dynamically respond to the action of factors of the internal and external environment. It is promising to study the state of the submucous nerve plexus, as well as the cellular composition of the population of neurons of the enteric nervous system of domestic and wild poultry.

Neuron-Glia Interaction in the Developing and Adult Enteric Nervous System

The enteric nervous system (ENS) constitutes the largest part of the peripheral nervous system. In recent years, ENS development and its neurogenetic capacity in homeostasis and allostasishave gained increasing attention. Developmentally, the neural precursors of the ENS are mainly derived from vagal and sacral neural crest cell portions. Furthermore, Schwann cell precursors, as well as endodermal pancreatic progenitors, participate in ENS formation. Neural precursorsenherite three subpopulations: a bipotent neuron-glia, a neuronal-fated and a glial-fated subpopulation. Typically, enteric neural precursors migrate along the entire bowel to the anal end, chemoattracted by glial cell-derived neurotrophic factor (GDNF) and endothelin 3 (EDN3) molecules. During migration, a fraction undergoes differentiation into neurons and glial cells. Differentiation is regulated by bone morphogenetic proteins (BMP), Hedgehog and Notch signalling. The fully formed adult ENS may react to injury and damage with neurogenesis and gliogenesis. Nevertheless, the origin of differentiating cells is currently under debate. Putative candidates are an embryonic-like enteric neural progenitor population, Schwann cell precursors and transdifferentiating glial cells. These cells can be isolated and propagated in culture as adult ENS progenitors and may be used for cell transplantation therapies for treating enteric aganglionosis in Chagas and Hirschsprung's diseases.

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.