Imagine a pair of molecular scissors capable of cutting DNA to replace the defective part with a healthy copy. These scissors have a name: Clustered Regularly Interspaced Short Palindromic Repeats, or CRISPR. And it could well become a technique of choice to cure genetic diseases, including several forms of cancer. Here’s all you need to know about it.

The technique

In a didactic video, the INSERM explains, by illustrating the Crispr-Cas9 genetic tool with a pair of scissors, how it can intervene to modify our DNA. It allows to cut any DNA sequence at a specific place, to remove it, and then replace it with a clean copy of the same sequence. This genome modification technique could then be used to cure genetic diseases.

The first trial

Following the approval of the American National Institutes of Health (NIH) in June 2016 to test Crispr-Cas9 biotechnology, the first tests, relayed by Nature, were carried out by a team of researchers from the Sichuan University in Chengdu, China. Scientists injected genetically engineered cells to recognize and attack the tumor cells of a patient with metastatic lung cancer, using the Crispr-Cas9 tool. In March 2017, New Scientist published the results. Less than one in 10 cells has been successfully repaired, a rate too low for the method to be usable on a large scale yet.

Implantation in hospitals?

Between 2016 and 2017, CRISPR has been tested several times to genetically modify embryos and remove HIV-infected cells from organisms. On August 23, 2017, Futurism announced a two-year partnership between researchers at Crispr-Cas9 and Massachusetts General Hospital to develop new cancer treatments based on this technology. “It is increasingly clear that Crispr-Cas9 technology could play an important role. (…) By combining our capabilities to modify the genes and the expertise of physicians, we hope to accelerate our progress in making these therapies a reality for cancer patients”, said Jon Terret, a scientist at CRISPR to GlobeNewswire.

DNA is fragile

One moment. Does that mean it is possible to modify the DNA as we please? The answer is no. In a statement released on May 29, 2017 on EurekAlert, researchers at the Columbia Medical Center warn about the collateral effects of CRISPR. The latter follows an experiment (carried out by themselves) of the technology on a mouse, to cure blindness. After the experiments, the mouse was kept under scientific supervision. Hundreds of unexpected mutations have been found in his genome. “None of these DNA mutations were predicted by computer algorithms widely used by researchers to search for off-target effects”, the team said. Stephen Tsang, one of the researchers, said that “we believe it is essential that the scientific community consider the potential hazards of all off-target mutations caused by CRISPR, including nucleotide mutations and mutations in non-coding regions of the genome”.