CRISPR 'Kill' Switch Could Make Gene Editing In Humans Safer [STUDY]

A weapon that viruses use in fighting against bacteria could be used to turn off the world's most powerful gene-editing tool. This new technique could reduce the risk that the bacterial "cut and paste" system, called CRISPR-Cas9 poses.

A teem of scientists discovered that a tiny protein shuts off the system in a petri dish, but they added that the protein also works in human cells. This new technique is not as simple as the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR), but it is less likely to miss its target which makes it safer than CRISPR for gene therapy in human patients.

Researchers at Yale and Carnegie Mellon Universities conducted a study that revealed a totally different method of editing genes and targeting mutations which cause diseases.

The CRISPR-Cas9 complex is a powerful tool in the bacterial immune defense against viruses. When a virus gains access to a bacterial cell, the bacteria mobilizes a sequence of DNA, known as CRISPR. The DNA consists of short blocks of repeating base pairs separated by spacer DNA.

It copies and inserts the viral DNA sequence into the CRISPR region and then produce two strands of RNA. The RNA works with an enzyme called Cas9, which acts as a snipping tool that goes into the target viral DNA and cuts it out.

The cell then repairs the DNA and replaces the deleted DNA snippet with another piece. The CRISPR system can be used as a genetic "find and replace," according to Live Science.

Genetic manipulation has been around for decades, but CRISPR has exploded in the last few years as a favored technique because it is versatile, inexpensive and relatively easy. Most of the key ingredients for this kind of gene editing can be ordered online and delivered by express mail.

The CRISPR system was invented by bacteria in the distant past. The Cells have their own complex systems for repairing the genome. CRISPR uses a natural enzyme called Cas-9 that can target a section of a genetic code and snip out mutated or damaged segments.

The only problem is that this is not yet a perfect science. CRISPR's genome-snipping is not always in the right place. Researchers claim progress in limiting off-target effects, but CRISPR to this point has not matured enough as a technique to be used in human therapies.

"It is so good at cutting the genome, it tends to make cuts at the wrong place, too. I think our technology is much harder to make, but we believe it is much more specific, with less off-target effects,"  Yale University geneticist and the co-author of the study, Peter Glazer says.

Glazer Teamed up with other scientists, including a professor of chemistry at Carnegie Mellon, Danith Ly, to develop a technique that takes synthetic genetic material - peptide nucleic acids (PNAs) and injects it directly into the bloodstream of a mouse that has a blood disease.

The report of the new study is based on the results of experiments on mice that have the blood disease - thalassemia, which is also common in humans. Thalassemia inhibits the levels of hemoglobin and is caused by a single mutation in the genetic code.

The synthetic PNAs injected into the mice, are designed to bind with their DNA to form a kind of bump on the genome that will cause the stretch of modified DNA to have a triple helix instead of the usual double helix.

The laboratory technique developed by Glazer and his colleagues requires a second maneuver, the deployment of a DNA patch that contains a normal and non mutant version of hemoglobin gene. The DNA strand will repair itself by plugging in the non mutant genetic patch.

However, it only works on a small percentage of cells, but the researchers noted that the level of efficiency is enough to suppress the diseases studied so far. Ly added that the goal is to try to replicate the mouse model in humans, according to Washington Post.

But Glazer said that fundamental truth about the human genome that it is really complicated and there is usually not a single genetic marker for physical traits or diseases. The researchers published their findings in Nature Communications.