However, limited experience is available on the application of CRISPR/Cas9 electroporation in cryopreserved T cells collected during clinical trials. To address this, we aimed to optimise a CRISPR/Cas9-mediated gene editing protocol compatible with peripheral blood mononuclear cells (PBMCs) samples routinely produced during clinical trials. PBMCs from healthy donors were used to generate knockout T-cell models for interferon-γ, Cbl proto-oncogene B (CBLB), Fas cell surface death receptor (Fas) and T-cell receptor (TCRαβ) genes.

The effect of CRISPR/Cas9-mediated gene editing on T cells was evaluated using apoptosis assays, cytokine bead arrays and ex vivo and in vitro stimulation assays.

Results

Our results demonstrate that CRISPR/Cas9-mediated gene editing of ex vivo T cells is efficient and does not overtly affect T-cell viability. Cytokine release and T-cell proliferation were not affected in gene-edited T cells. Interestingly, memory T cells were more susceptible to CRISPR/Cas9 gene editing than naïve T cells. Ex vivo and in vitro stimulation with antigens resulted in equivalent antigen-specific T-cell responses in gene-edited and untouched control cells, making CRISPR/Cas9-mediated gene editing compatible with clinical antigen-specific T-cell activation and expansion assays. Here, we report an optimised protocol for rapid, viable and highly efficient genetic modification in ex vivo human antigen-specific T cells, for subsequent functional evaluation and/or expansion.

Our platform extends CRISPR/Cas9-mediated gene editing for use in gold-standard clinically used immune-monitoring pipelines and serves as a starting point for development of analogous approaches, such as those including transcriptional activators and/or epigenetic modifiers.