Defects in long-distance neuronal wiring in the large intestine and in Hirschsprung’s Disease
This joint PhD project will be based at KU Leuven with a minimum 12 month stay at The University of Melbourne.
Project title: Stem cell therapy for the treatment of gastrointestinal motility disorders: targeting defects in neuronal wiring
The gastrointestinal (GI) tract is a complex organ that plays essential roles in the propulsion of food and waste products, nutrient and energy uptake, as well as host defense. The enteric nervous system (ENS), a meshed network of neurons and glia, controls most of these functions. During development, progenitor cells migrate down the gut and colonize the entire intestinal tube to form the ENS. However, in 1 out of 5000 live births, these progenitors do not reach the terminal end, causing the debilitating Hirschsprung’s disease, a condition in which innervation is absent from short or longer segments of large intestine. The underlying reasons are still largely unknown. Apart from this severe disorder, also subtler ENS defects can cause gut malfunction and discomfort. This is not surprising, as progenitors have the daunting task to travel long distances and bridge important junctions (esophagus to stomach, pylorus to the duodenum or distal ileum to colon).
In this project we will investigate how long-distance connections in the ENS operate and study how transplanted stem cells can repair specific lesions in the mouse ENS. Last, we will use biopsies and resection specimen from Hirschsprung’s patients to study how cellular environment affects hosting transplanted induced pluripotent stem cell (iPSC) derived precursors.
To investigate enteric neurocircuitry we will use advanced live imaging and dedicated microscopy equipment. Imaging techniques have the important advantage that activity in entire cellular networks can be visualized simultaneously. With the advent of genetically encoded optical tools, a number of older microscopy techniques have regained importance as the contrast does not have to be generated by the optical approach but arises from the expression system itself. In combination with advanced (e.g. 2-photon) microscopy, it is possible to leave tissues intact and study cellular activity in situ, even at high spatiotemporal resolution. Some of the work will rely on the measurements performed on a newly developed microscope, which has an upright and inverted part that can move independently from each other (see below).
This project is subdivided in three work packages that aim at addressing the objectives and test specific hypotheses:
Objective 1: To elucidate the ENS circuitry in the mouse ileo-colonic junction and mid-distal colon transition.
Hypothesis: The enteric neurons in the colon receive input from local and distant mucosa and send output to the terminal ileum as well as the proximal colon neurons to coordinate mixing, propulsion or storage of luminal contents.
Objective 2: To use mouse precursors and iPSC technology for targeted repair of subtle or more severe defects in ENS wiring.
Hypothesis: Small (induced) lesions can be repaired with minimal amounts of (mouse or iPSC derived) progenitors depending on differentiation state and injection site.
Objective 3: Investigate whether Hirschsprung’s disease tissue is permissive to (iPSC) induced progenitor implantation.
Hypothesis: In Hirschsprung’s disease, progenitors might fail to colonize the large intestine because local cellular environment is not receptive.
The exchange between both institutes guarantees exposure to both expert imaging as well as specific enteric stem cell technology.
The project will be complemented by the project on Stem cell therapy for the treatment of achalasia and gastroparesis and the collaboration will ensure a successful completion of the project.
Principal Investigators (PIs)
Co-Principal Investigators (co-PIs)