Molecular controls of T-lineage differentiation and thymus engraftment from human induced pluripotent stem cells 2056

Abstract Description The primary cell sources of T cell-based immunotherapies are autologous mature T cells from patients. Mature T cells are expanded in vitro and infused back for treatment after being armed by genes like chimeric antigen receptors. T cell resources limit this strategy. Human induced pluripotent stem cells (iPSC), which can be differentiated into mature T lineage cells in vitro, provide a potential alternative cellular source. We envision a strategy of transplanting iPSC-derived progenitor T cells (Pro-T) that are able to engraft the host thymus and develop into self-tolerant and self-MHC-restricted mature T cells via intrathymic selection steps. However, the successful engraftment of either iPSC-derived hematopoietic stem cells or Pro-T remains a major unresolved challenge. Our research aims to determine the necessary molecular cues required for iPSC-derived Pro-T thymus engraftment to enable the strategy. Our single-cell RNA-seq data shows that iPSC-derived Pro-T are more similar to fetal Pro-T than adult thymus, with a high signature Lin28b RNA expression. We used a fetal thymic organ culture (FTOC) approach to test thymus engraftment and RNA-seq to show that knocking-out LIN28B expression allows iPSC-derived Pro-T to engraft FTOCs, similar to cord blood-derived Pro-T. By further exploring LIN28B’s function during human T cell development, targeted LIN28B pathway inhibition could be used to enhance the iPSC-derived Pro-T engraftment ability for future clinical applications. Funding Sources Funding was provided by Grant 1158417 from the Cancer Research Society and the Leukemia & Lymphoma Society of Canada. Topic Categories Hematopoiesis and Immune System Development (HEM)