PROJECT SUMMARY Dendritic cells (DC) are responsible for initiating the most antigen-specific immune responses. In particular, DCs form an immunological synapse with T cells, orchestrated by three main signals, which forms the basis for antigen-specific immune responses. For high-throughput production of T cells specific to sub-dominant tumor- associated antigens, DC-like biological and mechanical properties should be emulated in culture platforms used for T cell expansion. The existing culture platforms with DC-like properties are made of rigid materials, which disable the movement of effector molecules required for T cell receptor clustering and thus remain inefficient in activating T cells. The central goal of this proposal is to fabricate synthetic DCs out of matrices whose mechanical properties are optimized for maximal expansion of antigen-specific central memory T cells. This research is organized around two key goals: (1) to develop mechanically optimized synthetic DCs providing three signals for efficient T cell expansion, and (2) to fabricate the stiffness-optimized synthetic micro-DCs for T cell growth in the form of 3D microcapsules. Successful completion of the proposed aims will provide a new paradigm for expanding T cells against individualized tumor-specific mutational antigens through interaction with novel mechanically optimized synthetic DCs. While this project is `high-risk', given the novel integration of biological and mechanical signals through synthetics DCs, it will launch a new direction for T cell manufacturing and may lead to `high-payoff' outcomes in the fields of immunoengineering and immunotherapy.