MIT researchers unveiled lipid nanoparticles that reprogram natural killer cells inside the body into CAR-bearing cancer killers. In mouse models of melanoma, lymphoma, and autoimmune hepatitis, the approach reportedly achieved high-efficiency in vivo cell engineering without viral vectors, aiming to simplify logistics relative to ex vivo cell manufacturing. The strategy positions lipid nanoparticle delivery as a platform for engineering immune effector cells directly in vivo, potentially shortening timelines and reducing manufacturing complexity. That could be especially relevant for indications where rapid immune activation and scalability matter. The next validation step will be translating engineering efficiency and safety from animal models to controlled human dosing studies, with particular focus on on-target activity, persistence, and off-tumor effects.