Artificial virus from China will help cure cancer
Chinese scientists have developed a new way to deliver DNA to animal and human cells for genetic modification. To do this, they use nanoparticles called artificial viruses by the authors of the study. They help the genes to penetrate into the cell nucleus, after which the genome editing mechanisms are activated. The biologists' article was published in the journal ACS Nano (Mout et al., Direct Cytosolic Delivery of CRISPR/Cas9-Ribonucleoprotein for Efficient Gene Editing – VM). It is briefly described on the EurekAlert website! (Overcoming hurdles in CRISPR gene editing to improve treatment).
To edit genes in cells, scientists use various approaches, including CRISPR/Cas9 technology. It allows you to precisely cut any selected sections of DNA, thus disabling certain genes. Viral vectors (created from modified and neutralized viruses) or plasmids – ring DNA molecules present in bacteria are usually used for delivery to eukaryotic cells. Since plasmids do not know how to penetrate eukaryotic cells themselves, in the latter they create pores using an electric field (electroporation), or use particles (liposomes) that merge with the outer membrane.
However, these methods have limitations, since viral vectors cannot carry large fragments of DNA and penetrate into all types of cells, and electroporation and liposomes are effective against cell cultures, but not tissues of living organisms.
To solve this problem, scientists have created an artificial RRPHC virus. It consists of a fluoropolymer core connected to the CRISPR/Cas9 system, as well as a shell formed by a hyaluronic biopolymer, polyethylene glycol and peptides R8-RGD. It has been shown that the hyaluronic biopolymer can bind to proteins located on the surface of cancer cells and specific to them.
After the introduction of RRPHC into the cell, the shell is cleaved by enzymes and the fluoropolymer core is released. In the CRISPR/Cas9 experiment, with the help of an artificial virus, it got inside the nucleus of cancer cells of naked mice, after which it attacked the MTH1 gene, which is active in many types of malignant tumors. It was found that the concentration of the protein encoded by MTH1 decreased after the introduction of nanoparticles.
According to scientists, their method will also be useful in editing the human genome. For example, it will be possible to extract defective cells from a patient, fix them with CRISPR/Cas9 and transplant them back. Similar experiments have already been conducted in China with T-lymphocytes of a cancer patient who had the gene suppressing immunity turned off. RRPHC is expected to increase the efficiency of such operations.
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09.02.2017