Graft-versus-Host Disease (GVHD) of the gut is a life-threatening condition that can occur after a donor bone marrow transplantation. Donor immune cells from the bone marrow graft attack and damage the gut of the patient that received the transplantation. The current available treatment for GVHD is not always successful. I try to model intestinal GVHD in the lab using mini-guts, so-called ‘intestinal organoids’, to better understand the interaction between donor immune cells and the gut and the role of gut damage. This way we hope to find new opportunities for therapies that protect the gut from these immune cells and restore transplant-associated damage.