Human Thymus Engineering

About This Grant

Abstract Recent advancements in immunotherapies have demonstrated the potential of antigen-specific patient-derived T cells to combat various diseases, notably cancer. Concurrently, induced pluripotent stem cell (iPSC)-derived technology offers a customizable, potentially limitless source of human T cells for immunotherapies. However, current efforts to generate functional T cells from iPSCs via in vitro selection fall short in achieving efficient T cell production and often produce aberrant T cell phenotypes compared to those educated in the native thymus. While thymic epithelium derived from iPSCs can support T cell differentiation after in vivo transplantation, there has not been success in identifying suitable mesenchymal cells from iPSCs to support thymic epithelium development ex vivo. Additionally, critical T cell education events involve trafficking from thymic cortical to medullary zones during differentiation but reproducing these zones or trafficking dynamics in vitro has not yet been demonstrated. The patterning of cell assemblies in space and time is crucial to tissue and organ development and is likely key to replicating the cortical and medullary thymic tissue sub-architecture in vitro. While the importance of chemical morphogen gradients has long been appreciated, it is increasingly clear that both the specific ECM molecules to which the cells adhere and the dynamic interaction between cell behavior and the matrix, with its time-varying mechanical properties, are important players in morphogenesis. Thus, tissue organization is impacted by the viscoelastic properties of the matrix, which vary from an elastic solid-like response to a liquid-like viscous response, in addition to ECM stiffness and composition. Our long-term goal is to combine iPSC-derived progenitors at the appropriate developmental stage with biomaterials that mimic thymic niches to scale the production of antigen-specific iPSC-derived human T cells for possible future clinical applications. We hypothesize that combining (1) developmentally matched, isogenic iPSC-derived thymic epithelium and mesenchyme with (2) instructive biomaterials that specify thymic zonal identity and allow for trafficking of differentiating iPSC-lymphoid progenitors between these zones will recreate thymic education in an in vitro platform and address the limitations observed in current iPSC-T cell derivations. We will explore this hypothesis through the following: (Aim 1) Developmentally match iPSC-derived mesenchyme and epithelial progenitors for thymic potential, (Aim 2) Engineer biomaterials and culture systems that mimic cortical and medullary thymic niches, and (Aim 3) Evaluate the impact of thymic mimicking niches on iPSC-derived T cell development and TCR repertoire. Success in this project will provide a robust platform for generating patient-specific T cells with functional competency comparable to thymus-educated T cells, generate insights that will have broad implications for cellular and molecular immunology as well as significantly advance the field of T cell immunotherapy using iPSCs.