A small study has seen success in using genetically modified immune cells to destroy HIV-infected cells over a long stretch of time. Researchers created genetically engineered stem cells that produce the CD4 cells that HIV targets and studied their effects in both cell cultures and macaque monkeys. The stem cells were tooled to produce HIV-specific versions of molecules known as chimeric antigen receptors (CARs), which supercharged the cells to combat the virus more effectively. The researchers found that the genetically modified stem cells safely engrafted in the primates’ bone marrow and became functional immune cells that flourished throughout the body. The result was a stable production of CAR-expressing immune cells that persisted for more than two years and were not apparently associated with any harmful effects.