Dynamic Changes in the Proximal Gut Neural Crest Stem Cell Population Are Associated with Successful Development of the Distal Enteric Nervous System in Rats

Abstract

Loss of signaling through the endothelin-B receptor (ET B ) leads to failure of vagal neural crest (NC) cell colonization of the developing gut and causes congenital distal intestinal aganglionosis [Hirschsprung disease (HSCR)] in humans and other mammals. Several studies suggest that cell-cell interactions and the number of NC cells behind the wavefront may play an important role in successful gut colonization. We compared the number and progression of enteric nervous system stem cells in the wild-type (WT) and HSCR rat gut using whole-mount immunohistochemistry for p75, culture and isolation of NC stem cells (NCSCs) by flow cytometry. Isolation and culture demonstrates that NCSCs enter the WT cecum between embryonic day (E) 13.5 and E14.5, and the number of NCSC in the colon significantly increases after E15.5. These findings are consistent with the caudal progression of the NC-cell wavefront by wholemount staining. During the period of WT colonic colonization of the proximal colon, we found significant differences in the small bowel NCSC pool between WT and HSCR rats. Whereas the proximal gut NCSC pool in WT rats is increasing behind the colonization wavefront, no such change occurs in the proximal NCSC pool in HSCR rats. Dynamic changes in the NCSC pool occur behind the NC colonization wavefront in the gut of WT rats. The absence of these changes in the HSCR rat may contribute to distal aganglionosis. Hirschsprung disease (HSCR) is a congenital abnormality of the enteric nervous system (ENS) and is the most common cause of congenital intestinal obstruction. HSCR is characterized by distal intestinal aganglionosis, and current treatment involves resection of the aganglionic segment of bowel. HSCR affects 1 in every 5000 children born worldwide and is associated with a variety of other congenital anomalies and syndromes. Persistent problems with enterocolitis, diarrhea, constipation, or encopresis are common after resection. Rarely, the length of aganglionic bowel is so great that resection leaves insufficient bowel for nutrient absorption. Morbidity and mortality from this disease remain high, even in developed countries (1).All of the neurons and glia of the ENS are derived from the neural crest (NC). The majority of enteric ganglia are derived from vagal NC cells that colonize the developing gut in a cranial-to-caudal progression. HSCR occurs when vagal NC cells fail to complete colonization of the distal gut. Several animal models of HSCR exist, and mutations in eight distinct genes are associated with this developmental abnormality in mammals. At least 10% of human HSCR is cause by defective signaling through endothelin-B receptor (ET B ) (2). The ET Bnull rat is a naturally occurring model of total colonic HSCR (3,4). Postnatally, at least 90% of animals have no ganglion cells beyond the ileocecal junction (3).Several

Biology of the adult enteric neural stem cell

“…A faulty expression of the ET‐3/ET‐B system results in an arrested migration of neural precursors, which differentiate before they reach their final destination, thus producing aganglionosis of the distal parts of the gut (Gershon,1998). Migration of NC‐derived cells depends not only on extrinsic regulating factors like GDNF or endothelins, cellular interactions within the front of the migrating wave as well as pressure exerted from the cells behind them are also important (Tsai and Gariepy,2005).…”

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

“…It is essential that the source of stem/progenitor cells can be sufficiently expanded in vitro and subsequently generate mature, functional neurons of the appropriate phenotype. Resident neural progenitor cells have been isolated from fetal and postnatal rodent and human bowel, which can give rise to enteric neurons following coculture with embryonic or postnatal rodent gut explants or human gut muscle, or following transplantation in the postnatal rodent gut (2,8,9,29,34,43,47,66,70). It is well established that, when maintained under optimal conditions, CNS neural progenitors are capable of rapid clonal expansion in vitro, with a population doubling time of around 44 h (42).…”

Recent advances and future research directions in neurogastroenterology and endocrinology recommendations of the National Commission on Digestive Diseases

“…The EDNRB/EDN 3 system provides another critical signalling pathway necessary for ENS development. Its activation enables colonization of the distal hindgut 54 . The EDNRB/EDN 3 signalling system is also important in the maintenance of the neural crest cells in a multipotential undifferentiated progenitor‐like state 55 .…”