Crispr Can Edit Directly Genes Inside Human Bodies

A decade ago, biologists Jennifer Doudna and Emmanuelle Charpentier published a landmark paper describing a natural immune system found in bacteria and its potential as a tool for editing the genes of living organisms. A year later, in 2013, Feng Zhang and his colleagues at the Broad Institute of MIT and Harvard reported that they’d harnessed that systemknown as Crispr, to edit human and animal cells in the lab. The work by both teams led to an explosion of interest in using Crispr to treat genetic diseases, as well as a 2020 Nobel Prize for Doudna and Charpentier.

Many diseases arise from gene mutations, so if Crispr could just snip out or replace an abnormal gene, it could in theory correct the disease. But one of the challenges of turning test tube Crispr discoveries into cures for patients has been figuring ouhow to get the gene-editing components to the place in the body that needs treatment.

One biotech company, Crispr Therapeutics, has gotten around that issue by editing patients’ cells outside the body. Scientists there have used the tool to treat dozens of people with sickle cell anemia and beta thalassemia—two common blood disorders. In those trials, investigators extract patients’ red blood cells, edit them to correct a disease-causing mutation, then infuse them back into the body.

But this “ex vivo” approach has downsides. It’s complex to administer, expensive, and has limited uses. Most diseases occur in cells and tissues that can’t be easily taken out of the body, treated, and put back in. So the next wave of Crispr research is focused on editingin vivo”—that is, directly inside a patient’s body. Last year, Intellia Therapeutics was the first to demonstrate that this was possible for a disease called transthyretin amyloidosis. And last week, the Cambridge, Massachusetts-based biotech company showed in-the-body editing in a second disease.