Cells exist along a spectrum from viable to dead. Yet most cell engineering has focused primarily on the live state. This review explores how controlled manipulation of cell death or arrest can be used to build effective, safer, and more predictable therapies. By engineering apoptosis, irreversible growth arrest, or synthetic gene circuits, cells can be programmed for functional outputs without relying on full viability. These approaches reduce heterogeneity, improve stability, and extend the therapeutic window. We introduce a framework for understanding engineered living, dying, and dead cell therapies on the basis of their activity, functions, and applications. Across this spectrum, engineered cells show promise for applications in immune modulation, drug delivery, and tissue regeneration. We also examine key methods that enable these designs, including genetic, physical, and materials-based tools. This perspective offers a path toward programmable and consistent cell-based therapies across diverse biomedical domains.
Lee-Kin et al. (Tue,) studied this question.