Fig. 5: Microrobot approaches for overcoming short-range tumour-targeting challenges.
From: Engineering microrobots for targeted cancer therapies from a medical perspective
a Intrinsic tumouritaxis exhibited by some bacteria, such as Clostridia, and higher eukaryotic immune cells. b FDA-approved pipeline for engineering CAR-T cells as a personalised cancer medicine (left). CAR-T cells target cancer cells by recognising tumour antigens on their surface that induce downstream TCR signalling, including cytotoxic perforin and granzyme reactions. c Targeting tumours via specific surface markers on the cells themselves, or on the vessels that supply the tumour. Using chemical/physical engineering methods, targeting moieties can be coupled directly to the microrobot surfaces or as part of non-motile nanoparticles, as illustrated for nanoliposomes as a key example. Analogous approaches can be applied to other nanoparticles (see also Fig. 1B). Particularly for the nanoparticle-coupling approach, care needs to be taken to limit microrobot size to regimes appropriate for the intended application (see main text for details). For most cellular strategies, the underlying cells can be genetically engineered to express targeting moieties on their surface. CAR chimeric antigen receptor, TCR T-cell receptor.
