Many hopes were and still are associated with the gene scissors CRISPR / Cas9 in medicine: Cut out the faulty gene, insert a functioning gene, the disease cured. The first CRISPR therapies for patients with sickle cell anemia and cancer have already made it into clinical studies. Cells are removed from the sick, treated with gene scissors and the repaired cells are returned. For many good reasons, medicine still shies away from changing the genome of cells directly in the body.
This article is from issue 5/2021 of the Technology Review. The magazine will be available from July 8th, 2021 in stores and directly in the heise shop. Highlights from the magazine:
“DNA editing is basically like surgery. They change the genome and have to live with what comes out of it, ”says Thorsten Stafforst, working group leader at the Interfaculty Institute for Biochemistry at the University of Tübingen. This is where RNA comes in. As messenger RNA, or mRNA for short, it transports the information in the DNA as a copy from the well-shielded cell nucleus to the part of the cell where it is produced. There the copy is translated into proteins that are currently needed as enzymes, messenger substances, building materials – or whatever. If the DNA has a defect, the mRNA has it too, which then leads to defective end products that cannot do their job in the body. The idea now is not to manipulate the well-shielded and sensitive original, but to correct the copy.
Small but powerful mutations could be temporarily corrected via RNA editing, the production of proteins could be stopped for a certain period of time or their function could be changed in individual organs or tissues. Since mRNA is produced on demand and the cell quickly breaks down unused RNA into its components in order to be able to build new ones, errors in treatment are not written into the genes for life. Somehow it is gene therapy anyway – only from the second row.
Cancer therapies, pain relievers, diagnostics
But RNA could not only play an important role in the treatment of hereditary diseases in the future. Researchers want to use modified RNA to support the immune system, for example in cancer therapies, or to develop effective pain relievers without the risk of addiction.
When it comes to diagnosis rather than cure, CRISPR / Cas and RNA are already a successful pair: The little sibling of CRISPRS / Cas9, the Cas13 system does not specialize in DNA, but in RNA and is an elegant tool for RNA Proof: Both SARS-Cov-2 and influenza, for example, are RNA viruses. Your genetic material does not consist of DNA but of RNA. When testing for RNA viruses, there are currently two options: fast, but unsafe with a rapid antigen test, or slowly but very reliably with a PCR test. The latter detects the viral RNA directly; the rapid tests that we use for Covid-19 rapid tests only recognize the surface structure of the virus.
New test systems necessary
The corona pandemic has made it clear that we need test systems that are as safe as PCR tests, but significantly faster. At MIT, researchers have developed a test system that closes this gap. It bears the name “Sherlock” and the virus detection can be seen with the naked eye – the sample lights up with a colored marker that is only released if the appropriate virus is in the sample. The is based on the principle, for example Covid-19 test offered by the US company IDT.
You can find out more about the many possibilities that RNA opens up for medicine – and which technologies are behind it – in the current issue 5/2021 of MIT Technology Review (in well-stocked newsagents and available in the heise shop).