In a project spearheaded by investigators at the University of California (UC) San Francisco (UCSF), scientists and collaborators have devised a new strategy to precisely modify human T cells using the genome-editing system known as CRISPR/Cas9. Because these immune-system cells play important roles in a wide range of diseases, from diabetes to AIDS to cancer, the achievement provides a versatile new tool for research on T cell function, as well as a path toward CRISPR/Cas9-based therapies for many serious health problems. Using their novel approach, the scientists were able to disable a protein on the T-cell surface called CXCR4, which can be exploited by HIV when the virus infects T cells and causes AIDS. The group also successfully shut down PD-1, a protein that has attracted intense interest in the burgeoning field of cancer immunotherapy, as scientists have shown that using drugs to block PD-1 coaxes T cells to attack tumors. The CRISPR/Cas9 system has captured the imagination of both scientists and the general public, because it makes it possible to easily and inexpensively edit genetic information in virtually any organism. T cells, which circulate in the blood, are an obvious candidate for medical applications of the technology, as these cells not only stand at the center of many disease processes, but could be easily gathered from patients, edited with CRISPR/Cas9, then returned to the body to exert therapeutic effects. But in practice, editing T cell genomes with CRISPR/Cas9 has proved surprisingly difficult, said Alexander Marson, Ph.D., a UCSF Sandler Fellow, and senior and co-corresponding author of the new study. "Genome editing in human T cells has been a notable challenge for the field," Dr. Marson said.
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