New concept in gastroenterology

Neural Stem Cell Therapy and Gastrointestinal Biology

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.

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.

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.

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.

Currently available therapies for gastrointestinal motility conditions are often inadequate. Recent scientific advances, however, have facilitated the identification of neural stem cells as novel tools for cellular replenishment. Such cells can be generated from a number of tissue sources including the gut itself. Neural stem cells can readily be harvested from postnatal human gut including by conventional endoscopy, and in experimental transplantation studies appear capable of generating a neo-Enteric Nervous System. Current initiatives are addressing pre-clinical proof of concept studies in vivo utilising animal models of disease. Although definitive cell replenishment therapies for gut motility disorders appear to be an exciting and realistic prospect, even in the short-term, a number of challenges remain to be addressed before definitive clinical application.

Midbrain, hindbrain and vagal neural crest (NC) produced abundant enteric nervous system (ENS) in co-grafted aneural hindgut and midgut, using chick–quail chorio-allantoic membrane grafts, forming complete myenteric and submucosal plexuses. This ability dropped suddenly in cervical and thoracic NC levels, furnishing an incomplete ENS in one or both plexuses. Typically, one plexus was favoured over the other. This deficiency was not caused by lower initial trunk NC number, yet overloading the initial number decreased the deficiency. No qualitative difference in neuronal and glial differentiation between cranial and trunk levels was observed. All levels formed HuC/D+ve, NOS+ve, ChAT+ve, and TH-ve enteric neurons with SoxE+ve, GFAP+ve, and BFABP+ve glial cells. We mathematically modelled a proliferative difference between NC populations, with a plexus preference hierarchy, in the context of intestinal growth. High proliferation achieved an outcome similar to cranial NC, while low proliferation described the trunk NC outcome of incomplete primary plexus and even more deficient secondary plexus. We conclude that cranial NC, relative to trunk NC, has a positionally-determined proliferation advantage favouring ENS formation. This has important implications for proposed NC stem cell therapy for Hirschsprung's disease, since such cells may need to be optimised for positional identity.

Gut motility disorders represent a significant challenge in clinical management with current palliative approaches failing to overcome disease and treatment-related morbidity. The recent progress with stem cells to restore missing or defective elements of the gut neuromusculature offers new hope for potential cure. Focusing on enteric neuropathies such as Hirschsprung's disease, the review discusses the progress that has been made in the sourcing of putative stem cells and the studies into their biology and therapeutic potential. It also explores the practical challenges that must be overcome before stem cell-based therapies can be applied in the clinical arena. Although many obstacles remain, the speed of advancement of the enteric stem cell field suggests that such therapies are on the horizon.

Motility patterns in the mature intestine require the coordinated interaction of enteric neurons, gastrointestinal smooth muscle, and interstitial cells of Cajal. In Hirschsprung's disease, the aganglionic segment causes functional obstruction, and thus the enteric nervous system (ENS) is essential for gastrointestinal motility after birth. Here we review the development of the ENS. We then focus on motility patterns in the small intestine and colon of fetal mice and larval zebrafish, where recent studies have shown that the first intestinal motility patterns are not neurally mediated. Finally, we review the development of gastrointestinal motility in humans.