Abstract
Here, we describe an assay for intestinal permeability in mouse intestinal organoids, although this may also be adapted for other species. Propidium iodide (PI) does not penetrate intact biological membranes and thus cannot enter the lumen of intact organoids. Passage of PI within the lumen can be induced by tight junction disruption or epithelial cell death. This technique measures PI-stained extruded dead cells within the organoid lumen to analyze the effect of insults, toxins, or treatments on intestinal organoid permeability.