Allogeneic hematopoietic stem cell transplantation(allo-SCT)is curative therapy for various hematological diseases. Graft-versus-host disease(GVHD)and infection remain the main problems in allo-SCT. Gastrointestinal tract is targeted by GVHD. In intestinal GVHD, intestinal stem cells and Paneth cells reside at the base of crypts are damaged by donor T cells. These damage leads to disruption of intestinal mucosal barrier and intestinal dysbiosis, resulting in more exaggerated GVHD. Recently, we and others have reported that R-Spondin1 and interleukin-22 as factors regenerated intestinal tissue homeostasis in murine model of bone marrow transplantation. It is important to understand biology of various cells targeted by intestinal GVHD and develop novel methods to protect them from GVHD damage.