SMOOTH-MUSCLE FROM AGANGLIONIC BOWEL IN HIRSCHSPRUNGS-DISEASE IMPAIRSNEURONAL DEVELOPMENT IN-VITRO

Hirschsprung's disease results from the congenital absence of enteric neurons in human distal colon. The reason for aganglionosis is unknown but may reflect an unfavourable microenvironment for neuronal develop ment. We asked if smooth muscle cells from the aganglionic region coul d affect neuronal development in vitro. Neurons from neonatal mouse su perior cervical ganglia were added to cultures of smooth muscle obtain ed from normal or aganglionic regions of five patients with Hirschspru ng's disease. Although neurons initially showed more rapid attachment to aganglionic smooth muscle, this was equal by 60 min and thereafter. Progressive increase in the diameter of the nerve cell body was chara cteristic of normal maturation in vitro. This was consistently inhibit ed by 15-22% in neurons grown on aganglionic muscle compared with norm al controls over the 6-day test period (P<0.05). This phenomenon was p reserved when the smooth muscle cells were lysed by brief exposure to distilled water before initiation of coculture (16-18% inhibition; P<0 .05). These data imply that smooth muscle of the aganglionic colon is less favourable for neuronal development than the normally innervated region and suggest a membrane-linked factor. Clearly, this persists in postnatal life and in vitro and may reflect an abnormality of cellula r interaction causing Hirschsprung's disease.