Glial Cell Derived Neurotrophic Factor Induces Enteric Neurogenesis and Improves Colon Structure and Function in Mouse Models of Hirschsprung Disease

Background & Aims: Hirschsprung disease (HSCR) is a life-threatening birth defect in which the distal colon is devoid of enteric neural ganglia. HSCR is treated by surgical removal of aganglionic bowel, but many children continue to have severe problems after surgery. We studied whether administration of glial cell derived neurotrophic factor (GDNF) induces enteric nervous system regeneration in mouse models of HSCR. Methods: We performed studies with four mouse models of HSCR: Holstein (HolTg/Tg, a model for trisomy 21-associated HSCR), TashT (TashTTg/Tg, a model for male-biased HSCR), Piebald-lethal(Ednrbs-l//s-l, a model for EDNRB mutation-associated HSCR), and Ret9/- (with aganglionosis induced by mycophenolate). Mice were given rectal enemas containing GDNF or saline (control) from postnatal days 4 through 8. We measured survival times of mice, and colon tissues were analyzed by histology, immunofluorescence, and immunoblots. Neural ganglia regeneration and structure, bowel motility, epithelial permeability, muscle thickness, and neutrophil infiltration were studied in colon tissues and in mice. Stool samples were collected, and microbiomes were analyzed by 16S rRNA gene sequencing. Time-lapse imaging and genetic cell-lineage tracing were used to identify a source of GDNF-targeted neural progenitors. Human aganglionic colon explants from children with HSCR were cultured with GDNF and evaluated for neurogenesis. Results: GDNF significantly prolonged mean survival times of HolTg/Tgmice, Ednrbs-l//s-l mice, and male TashTTg/Tg mice, compared with control mice, but not Ret9/- mice (which had mycophenolate toxicity). Mice given GDNF developed neurons and glia in distal bowel tissues that were aganglionic incontrol mice, had a significant increase in colon motility, and had significant decreases in epithelial permeability, muscle thickness, and neutrophil density. We observed dysbiosis in fecal samples from HolTg/Tg mice compared with feces from wild-type mice; fecal