Functionalizing Hydrogel Nanovials with Vesicles Mimicking Antigen-Presenting Vesicles and Cancer Exosomes Improves T Cell Capture and Activation.

Recent advances have demonstrated the application of microcavity-containing hydrogel microparticles, known as nanovials, for massively parallel and high-throughput screening of therapeutic T cell populations for adoptive cell therapies. Nanovial cavities coated with peptide-MHC (pMHC) or antigen tetramers selectively bind to their cognate T cell receptor (TCR) or chimeric antigen receptor (CAR) to activate T cells and capture secreted cytokines. However, binding of tetramers or recombinantly expressed antigen by T cells may not reflect physiological T cell activation or cytotoxicity, as the binding interface is not fully representative of the natural immunological synapse formed between T cells and professional antigen-presenting cells (APCs). Here, we leverage the recent discovery of an ESCRT- and ALIX-binding region (EABR) sequence to generate antigen-presenting vesicles and cancer-mimicking exosomes from standard HEK293T and Expi293F cell cultures. EABR-mediated vesicles present natural, full-length oncologically relevant membrane proteins embedded in lipid bilayers to functionalize the nanovial cavity with cell-like membranes. Hydrogel nanovials functionalized with the EABR-mediated vesicles show improved T cell capture of 1G4 T cells and enhanced induction of secretion in HER2 CAR-T cells compared to hydrogel surfaces functionalized with recombinantly expressed soluble proteins.