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Studies of human T cell development require robust model systems that recapitulate the full span of thymopoiesis, from hematopoietic stem and progenitor cells (HSPCs) through to mature T cells. Existing in vitro models induce T cell commitment from human HSPCs; however, differentiation into mature CD3+TCRab+ single positive (SP) CD8+ or CD4+ cells is limited. We describe here a serum-free, artificial thymic organoid (ATO) system that supports highly efficient and reproducible in vitro differentiation and positive selection of conventional human T cells from all sources of HSPCs. ATO-derived T cells exhibited mature naïve phenotypes, a diverse TCR repertoire, and TCR-dependent function. ATOs initiated with TCR-engineered HSPCs produced T cells with antigen specific cytotoxicity and near complete lack of endogenous TCR Vβ expression, consistent with allelic exclusion of Vβ loci. ATOs provide a robust tool for studying human T cell development and stem cell based approaches to engineered T cell therapies.

Summary The ability to generate T cells from self-renewing pluripotent stem cells (PSC) has the potential to transform the current practice of autologous T cell immunotherapy into universal off-the-shelf products. However, differentiation of human PSCs into mature, conventional T cells has been challenging with existing methods. We report that a 3D artificial thymic organoid (PSC-ATO) system induced efficient differentiation of human embryonic stem cell and induced pluripotent stem cell-derived mesoderm progenitors to mature, functional T cells with a diverse T cell receptor (TCR) repertoire. This continuous culture system supported both hematopoietic specification and terminal differentiation to naïve CD3+CD8αβ+ and CD3+CD4+ conventional T cells. Introduction of an MHC class I-restricted TCR in PSCs produced naïve, antigen-specific cytotoxic CD8αβ+ T cells which lacked endogenous TCR Vβ expression. Functional assays and RNA sequencing aligned PSC-derived T cells with primary naïve CD8+ T cells. The PSC-ATO system presented here is an efficient platform for generating functional, mature T cells from human PSCs.

Background Childhood cancer survivors are at increased risk of morbidity and mortality. To further characterize this risk, this study aimed to compare the prevalence of diabetes mellitus (DM) in childhood cancer survivors and their siblings. Methods Participants included 8599 survivors in the Childhood Cancer Survivor Study (CCSS), a retrospectively ascertained North American cohort of long-term survivors who were diagnosed 1970–1986, and 2936 randomly selected siblings of CCSS survivors. The main outcome was self-reported DM. Results Survivors and siblings had mean ages of 31.5 years (range, 17.0–54.1) and 33.4 years (range, 9.6–58.4), respectively. DM was reported in 2.5% of survivors and 1.7% of siblings. Adjusting for body mass index (BMI), age, sex, race/ethnicity, household income, and insurance, survivors were 1.8 times more likely to report DM (95% confidence interval [CI], 1.3–2.5; P<0.001) than siblings, with survivors who received total body irradiation (odds ratio [OR], 12.6; 95% CI, 6.2–25.3; P<0.001), abdominal irradiation (OR, 3.4; 95% CI, 2.3–5.0; P<0.001) and cranial irradiation (OR, 1.6; 95% CI 1.0–2.3; P=0.03) at increased risk. In adjusted models, increased risk of DM was associated with: total body irradiation (OR 7.2; 95% CI, 3.4–15.0; P<0.001); abdominal irradiation (OR 2.7; 95% CI, 1.9–3.8; P<0.001); alkylating agents (OR 1.7; 95% CI, 1.2–2.3; P<0.01); and younger age at diagnosis (0–4 years; OR 2.4; 95% CI 1.3–4.6; P<0.01). Conclusions Childhood cancer survivors treated with total body or abdominal irradiation have an increased risk of diabetes that appears unrelated to BMI or physical inactivity.

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