Deng Hongkui Group reported their recent work on Cell Stem Cell with the title “Directed Differentiation of Human Embryonic Stem Cells into Thymic Epithelial Progenitor-like Cells Reconstitutes the Thymic Microenvironment In Vivo”. Thymus transplantation has great clinical potential for treating immunological disorders, but the shortage of transplant donors limits the progress of this therapy. In this study, the researchers demonstrated that human thymic epithelial progenitor-like cells could be generated from human embryonic stem cells in a stepwise manner, mimicking in vivo thymus organogenesis. When transplanted into nude mice, the thymic epithelial progenitor-like cells further matured into thymic epithelium and supported mouse T cell development. Moreover, the thymic epithelium could also enhance human T cell generation in NOD/SCID mice engrafted with human hematopoietic stem cells. These findings could facilitate human embryonic stem cells -based replacement therapy and provide a valuable in vitro platform for studying human thymus organogenesis and regeneration.