[Culture and application of thymic organoids: a review]

The thymus is a pivotal immune organ of the human body, and it is the place where T cells differentiate and mature. The damage of thymus would easily induce autoimmune diseases and even malignant tumors. For years, researchers have been exploring the process of T cell development and revealing the mechanism of thymic injury and regeneration generally through the monolayer culture system of T cells in vitro. However, the classic monolayer culture system could neither reproduce the unique three-dimensional epithelial reticular structure of the thymus, nor provide the cytokines and growth factors required for the directed differentiation of hematopoietic stem cells into T cells. Thymic organoid technology utilizes cells with stem cell potential to simulate the anatomical structure of the thymus and the signaling pathway mediated by thymic epithelial cells in vitro through three-dimensional culture, which is particularly close to the microenvironment of the thymus in vivo. Thymic organoids show great potential in the study of T cell differentiation and development, thymus-related diseases, reconstruction of immune function, and cell therapy. This paper summarizes the methods for culturing thymic organoids, followed by comparing the advantages and disadvantages of the scaffolds used for culturing. The applications of thymic organoids in the disease model, tumor-targeting therapy, regenerative medicine, and organ transplantation were also discussed, with possible future research directions prospected.