De novo construction of T cell compartment in humanized mice engrafted with iPSC-derived thymus organoids

Hematopoietic humanized (hu) mice are powerful tools for modeling the action of human immune system and are widely used for preclinical studies and drug discovery. However, generating a functional human T cell compartment in hu mice remains challenging, primarily due to the species-related differences between human and mouse thymus. While engrafting human fetal thymic tissues can support robust T cell development in hu mice, tissue scarcity and ethical concerns limit their wide use. Here, we describe the tissue engineering of human thymus organoids from inducible pluripotent stem cells (iPSC-thymus) that can support the de novo generation of a diverse population of functional human T cells. T cells of iPSC-thymus engrafted hu mice could mediate both cellular and humoral immune responses, including mounting robust proinflammatory responses upon TCR engagement, inhibiting the growth of allogeneic tumor grafts and facilitating efficient Ig class switching. Our findings suggest that hu mice engrafted with iPSC-thymus can serve as a novel animal model to study human T cell-mediated immunity and accelerate the translation of animal studies into the clinic. Cells used in this study were thymic epithelial cells (TECs) derived from iPSCs and then grown in different culture conditions. One set of samples is TECs grown in a 2-dimensional cell culture environment, while the other is a set of TECs grown in a 3-dimensional alginate capsule. No replicates or controls were used. Reference samples were taken from the publically available datasets generated by Campinoti et al. (2020) and Zeng et al. (2019).