Intramuscular enteric glia persist in Hirschsprung disease and undergo neurogenesis in response to GDNF-NCAM1 signaling

Hirschsprung disease (HSCR) is a neurocristopathy, yet paradoxically, neural crest-derived EGCs are present within the muscle of the affected region. This study investigates the molecular identity, origins, and neurogenic potential of EGCs in the aganglionic mouse and human colon. We utilized single-cell RNA sequencing (scRNA-seq), immunohistochemistry, and in vitro culture of EGCs from aganglionic and ganglionated segments of Ednrb-null mice (Plp1-GFP;Baf-tdT;Ednrb^-/-) and human HSCR tissues. Neurogenic potential and network formation were assessed, and the effects of glial cell line-derived neurotrophic factor (GDNF) on neurogenesis were evaluated. scRNA-seq and immunohistochemistry revealed the absence of GFAP+ intraganglionic (IG) glia in aganglionic colon, while CAMK2b+ extraganglionic (EG) glia and Schwann-like cells (SLCs) were present. EG glia exhibited a transcriptional profile similar to SLCs, suggesting a possible shared embryonic origin. EGCs in the aganglionic segment (comprising EGs and SLCs) exhibited reduced neurogenic potential and network complexity compared to EGCs from the ganglionated region (comprising EGs and IGs). GDNF partially restored neurogenic capacity and enhanced network complexity of EGCs isolated from the aganglionic segment, acting through a non-canonical NCAM1-dependent pathway independent of RET signaling.