Properties of enteric nervous system stem cells and their potential for clinical transplantation

The enteric nervous system (ENS), the intrinsic innervations of the gastrointestinal tract, consists of multiple neuronal and glial cells. However, during embryonic development, abnormalities in the colonization of the gut by ENS progenitors can result in lack of neurons in the colon and subsequent defective bowel function, a phenotype which characterizes the congenital disorder Hirschsprung's disease (HSCR). The current treatment of HSCR is surgery but chronic post-operative complications have stimulated research aimed at developing the use of ENS progenitor cell transplants as an adjunct therapy. During the last two decades ENS progenitor cells and their neuronal and glial derivatives have been cultured in vitro as aggregates called neurospheres. Upon transplantation into explants of aganglionic embryonic colon, neurospheres have been shown to restore a normal pattern of contractility. However, the behaviour of neurosphere cells and the mechanisms controlling them either in the neurosphere or after transplantation still need to be established. Consequently, the aim of this study was to investigate the proliferation, differentiation and migratory behaviour of ENS progenitors in vitro. Results showed that although neurospheres are a mixture of cells expressing different markers, dividing cells follow a pattern. It was demonstrated that cells with high proliferation rate were localized at the periphery of the neurosphere. Upon division some of these cells moved towards the centre and slowed down or stopped proliferating, whereas the rest remained at the periphery and divided further. In both cases, their phenotype changed and they started expressing markers of differentiation. The phenotypic change and the proliferation rate were found to be regulated by the Notch signalling pathway. In addition, transplantation experiments in bowel explants showed that these cells were able to migrate into the gut in the presence or absence of an intrinsic ENS. Migration was also observed when neurospheres were transplanted to different tissues indicating the high migratory potential of these cells. In conclusion the results of the present thesis give more light in understanding the properties and behaviour of neurosphere cells and represent one step closer to the treatment of bowel disorders such as HSCR.EThOS - Electronic Theses Online ServiceGBUnited Kingdo