Mar 06, 2014 7:06 PM GMT
Engineering a patient’s own immune cells to resist HIV could eliminate the need for lifelong antiretroviral therapies.
The immune cells of HIV patients can be genetically engineered to resist infection, say researchers. In a small study in humans, scientists report that by creating a beneficial mutation in T cells, they may be able to nearly cure patients of HIV.
In a study published in the New England Journal of Medicine on Wednesday, researchers report that they can use genome editing to re-create the rare mutations responsible for protecting about 1 percent of the population from the virus in infected patients. They report that some of the patients receiving the genome-modifying treatment showed decreased viral loads during a temporary halt of their antiretroviral drugs. In one patient, the virus could no longer be detected in his blood.
Zinc-finger nucleases are one of a few genome-editing tools that researchers use to create specific changes to the genomes of living organisms and cells (see “Genome Surgery”). Scientists have previously used genome-editing techniques to modify DNA in human cells and nonhuman animals, including monkeys (see “Monkeys Modified with Genome Editing”). Now, the NEJM study suggests the method can also be safely used in humans.
From each participating patient, the team harvested immune cells from the blood of the patients. They then used a zinc finger nuclease to “break” copies of the CCR5 gene that encodes for proteins on the surface of immune cells that are a critical entry point of HIV. The cells were then infused back into each patient’s bloodstream. The modification process isn’t perfect, so only some of the cells end up carrying the modification. “About 25 percent of the cells have at least one of the CCR5 genes interrupted,” says Edward Lanphier, CEO of Sangamo Biosciences, the Richmond, California, biotech company that manufactures zinc finger nucleases.
Because the cells are a patient’s own, there is no risk of tissue rejection. The modified T cells are more resistant to infection by HIV, say the researchers.