Researchers have developed a gene engineering approach that could be used to combat cocaine addiction. The University of Chicago’s Ming Xu and colleagues hypothesized that skin cells could be take from patients and altered in the lab to have an extra enzyme, butyrylcholinesterase, that quickly breaks cocaine down, it adds. These altered cells could then, as part of an organoid, be implanted under patients’ skin. The approach appears to work in mice. They used a CRISPR-based approach to edit mouse cells to express enhanced form of butyrylcholinesterase before transplanting them back. Mice treated in this way broke down cocaine more quickly and were less likely to seek out cocaine than untreated mice. Treatment also prevented mice given lethal doses of cocaine from dying.