MOSCOW, 12 APR – RIA Novosti. Molecular biology first successfully applied the genomic editor CRISPR/Cas9 to “fix” the DNA in stem cells of people suffering from sickle-cell anaemia, which gives hope for a speedy cure of this genetic disease, said in an article published in the journal Science Translational Medicine.
“We excite the prospects of applying this technology. There is still much to be done before such a therapy is available at clinics, but we hope that our work will pave the way for new treatments for patients with sickle cell anemia,” said Jacob Korn (Jacob Corn) from the University of California at Berkeley (USA).
Genomic editor CRISPR/Cas9, named chief scientific breakthrough 2015, was created by American scientist Feng Zhang (Feng Zhang) and several other molecular biologists about three years ago, and since then it has undergone several upgrades that allow scientists to use it to edit the genome with absolute precision.
Today, scientists are seriously considering the use of this technology for the treatment of congenital or genetically determined diseases – for example, degeneration of muscles, pathologies of the retina, the first experiments on the treatment of which has already been held, and also to clean the genome from HIV and other retroviruses.
Korn and his colleagues have added to the number of such diseases and sickle-cell anaemia – a serious blood disease, resulting from mutations in one of the genes responsible for the synthesis of hemoglobin. As a result of typographical errors in the gene HBB the hemoglobin molecule in red blood cells become deformed, stretching in a sort of “crescents”, and lose their normal ability to carry oxygen.
Such changes lead to a lot of unpleasant consequences – the organism constantly tests oxygen starvation themselves blood cells are rapidly destroyed, which overloads the bone marrow and spleen, and the man is constantly in pain, fatigue and suffering from inflammation and arthritis.
The authors suggested that some of the negative effects of anemia can be neutralized by removing a corrupt version of the HBB gene in stem cells of the bone marrow responsible for red blood cell production, and replace it with a normal copy of the DNA segment.
Using CRISPR/Cas9 and a new “ultra-precision” version of the Cas9 protein, open a Zhang in the past year, scientists have tried to carry out this genetic “surgery” using hematopoietic stem cells extracted from the blood of several volunteers, who suffered from sickle cell anemia.
After the technology on stem cells of healthy people, DNA which they inserted the “wrong” version of the HBB gene, biologists have successfully edited the genomes initially 6-11% of hematopoietic stem cells, and the total number of “fixed” cells in the end, after their transformation into erythrocytes, was 66-72%.
According to scientists, the side effects from this edit, or disappeared, or was vanishingly small. Even this number of cells, as the scientists explain, is enough to suppress most of the negative effects of anemia, because sickle red cells very poorly cope with their tasks.
These cell cultures, the scientists transplanted bone marrow in mice to test their viability. The experiments showed that the cells engrafted and produced red blood cells at least during 16 weeks of observation, which speaks about the clinical applicability of this technology. As I hope Korn and his colleagues, this technology can move to clinical practice in the next five years.