Efficient non-viral CAR-T cell generation via silicon-nanotube-mediated transfection

Cell-based immunotherapy such as chimeric antigen receptor (CAR)-T therapy holds great promise in treating cancer and other diseases; but the current viral-based method represents a significant cost and safety hurdle. Here, we show for the first time successful CAR transfection into primary T cells via vertically aligned silicon nanotube (SiNT) arrays. SiNT-mediated transfection achieves comparable or even higher delivery efficiency (20-37%) and expression efficiency (18-24%) to that achieved by electroporation. Scanning electron microscopy imaging after focused ion beam milling demonstrated the tight T cell-SiNT interface. The induced membrane invaginations and the proximity between individual SiNTs and the nucleus might enhance endocytic pathways, and enable direct delivery of CAR construct into the nucleus, thus resulting in higher CAR expression efficiency. SiNT-interfacing also results in faster proliferation of T cells compared to cells transfected by electroporation; non-activated T (N_SiNT) cells undergo higher numbers of cell division than pre-activated ones (A_SiNT). By co-culturing with target lymphoma Raji cells, we prove that SiNT-transfected CAR-T cells can suppress Raji cell growth, indicated by significant increase in effector:target (E:T) ratio (by up to 30.7-fold). While SiNTs induce an overall upregulation of cytokine production in T cells, N_SiNT T cells exhibited high increase in secretion of IFNc and IL-6, and relatively high in TNFa, which could contribute to their enhanced killing ability (-96% cytotoxicity), demonstrated by their stronger inhibition on target Raji cells through luciferase assay. The results demonstrate the capacity of SiNT-mediated transfection of generating effective anti-lymphoma CAR-T cells. Considering the growing potential of cell-based therapies, we expect that a non-viral nanoinjection platform such as ours will facilitate the full realization of their therapeutic promise.