Designing drug delivery systems for cell therapy

Cell therapies, such as immune cell and stem cell therapies, are being preclinically and clinically explored for the treatment of various diseases, but are often limited by low efficacy and safety concerns. Drug delivery systems at the nanoscale, microscale and macroscale can be designed to improve cell therapies by optimizing pharmacokinetics, cell function and cell viability, and by preventing cell exhaustion and immunogenicity. In this Review, we discuss the engineering of drug delivery systems at various scales to improve the biological functions of therapeutic cells, modulate tissue environments to promote the survival and efficacy of therapeutic cells, enable targeted delivery of therapeutic agents by transferred cells and provide protective barriers for cells in vivo. We further outline crucial milestones for the clinical translation of cell therapies integrated with drug delivery systems and highlight manufacturing challenges.