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In a big bracket update, CRISPR can now edit several genes at once

We have already seen many different uses for CRISPR gene editing – precise cutting and pasting of certain genes into DNA. Now the researchers have come up with a process improvement that could allow dozens or even hundreds of genes to be edited at the same time.

According to the team, this could open up any new possibilities, enabling scientists to reprogram cells in a larger scale and in more sophisticated ways: studying complicated genetic disorders, for example, or trying to replace damaged cells with healthy ones.

For the most part, CRISPR techniques modify only one gene at a time, although at least seven genes are edited together. According to this latest study, the new method can reach 25 targets within the genes simultaneously.

"Our method allows us, for the first time, to systematically change the entire gene network in one step," says biochemist Randall Platt, of ETF Zurich in Switzerland. "Thanks to this new tool, we and other scientists can now achieve what we could only dream of doing in the past."

The key to the new multi-targeting system is the stabilized RNA structure in plasmid or circular DNA molecule, capable of retaining and processing additional RNA molecules. These RNA molecules act as address labels for targeting genes, so the more the plasmid can carry, the more parts of the cells can be targeted to scientists.

Like the RNA molecules, the plasmid carries the Cas enzyme, which does the right job of binding and cleaving. Cas9 is the most commonly used enzyme, but here scientists have switched to Cas12a, an enzyme that has previously been shown to improve the accuracy of CRISPR editing.

In their experiments, the scientists were able to successfully insert their new plasmid into human cells in the laboratory.

These changes to the CRISPR standard process may mean that scientists will be able to do more extensive gene editing. Genes and proteins in cells interact in incredibly complex ways, and sometimes just doing one piece or changing at a time can be limiting.

For example, the new technique may mean that the activity of certain genes can be increased at the same time as the activity of other genes is reduced – and all these operations can be scheduled with greater precision.

However, there is a catch here. We do not know exactly how more changes can occur in the body being regulated. As we've seen in the past, there can be unexpected secondary changes, and the more genes you change, the greater the risk.

"Direct sequences of repetition and distances containing complementary sequences [..] could generate complex secondary RNA structures that affect the maturation of CRISPPR RNA in cells, "the team wrote in their paper.

"As a result, complementary regions in the pre-CRISPR RNA must be considered to improve the maturation of CRISPR RNA. Future work to overcome these limitations will open numerous applications for high-multiplex genome generation."

We have already seen that CRISPR is used to reduce the genes responsible for the diseases and to destroy the superbugs. Scientists say there is still much to come, and they now have an even more versatile and comprehensive tool available.

"Our method provides a powerful platform for researching and orchestrating sophisticated genetic programs that address complex cell behavior," the team wrote.

The research is published in Natural methods.

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