Scientists from the United States for the first time successfully «repaired» DNA in the human embryo

© Fotolia / Dan RaceУченый with a model DNA in a test tubeScientists from the United States for the first time successfully «repaired» DNA in the human embryo© Fotolia / Dan Race

Sukrat Mitalipov and his colleagues have described the successful correction of mutations in the DNA of a human embryo with a genomic editor CRISPR/Cas9 and published the results of their experiments in the journal Nature.

«Thanks to this therapy, each generation of descendants of that embryo would be spared the health problems of the heart, as we removed the defective gene associated with hypertrophic cardiomyopathy. Using this approach, we can save many families from the disease, and ultimately – to clear of this mutation all of humanity,» said Mitalipov.

Two years ago in the scientific community began to creep rumors that a number of Chinese scientists and their American colleagues have conducted a series of experiments to edit and replace defective genes in human embryos, the editorial office of the news service of the journal Nature said a number of unnamed molecular biologists.

In April 2015, these rumors were confirmed – Chinese scientists published a paper in the journal Protein & Cell, in which they described the results as a whole rather unsuccessful attempts to adapt rapidly gaining popularity system for genome editing CRISPR/Cas9 for the manipulation of human DNA inside the embryo.

Similar to the results of experiments and the fact of editing of the genome of embryos have led many politicians and scientists to think about a moratorium on such experiments in the U.S., Britain and several other countries.

Sukrat Mitalipov known molecular biologist from the University of medicine and health Oregon in Portland (USA) and his colleagues found out why the experiences of Chinese biologists has led to such consequences, and conducted the first successful operation to edit the DNA of a live embryo.

As they say scientists, the first experiments they performed on an already fertilized egg, showing that the editing of their genome has often led not only to the emergence of new errors in DNA, but also to chimerisation the part of cells that shared a mother cell, contained in his edited genes, others are old, mutant version.

Watching the editing process of DNA, scientists came to the conclusion that the error can be avoided if you change the genome of the embryo after the fertilization and during the penetration of the sperm into the egg and merging their genetic material.

100% success and 0% of errors

Following this idea, the scientists collected about six dozen full eggs, which they donated to women volunteers, and attempted to fertilize them with the sperm of men who suffered from hypertrophic cardiomyopathy, a serious hereditary disease that dramatically increases the predisposition to sudden cardiac arrest and instant death.

Hypertrophy of one of ventricles of the heart, as the scientists explain, usually caused by the appearance of small «typos» in the gene MYBPC3, and damage to even one of the two copies of this DNA leads to the development of the disease. To cure this disease is impossible, and only the correction of defective versions of the gene before the birth of the child will help him avoid a similar fate.

Experiments Mitalipov and his colleagues showed that edit the DNA of the embryo during fertilization eliminates virtually all problems associated with the inaccuracy of the work CRISPR/Cas9. Wrong version of the gene MYBPC3 was removed from the DNA of all 58 embryos, and the correct version has been inserted into the genomes of 72% of the embryos.

In any case, scientists have documented the development of chimerism or the occurrence of «typos» in other regions of the DNA that are not related to MYBPC3. All embryos developed normally for several days, after which Mitalipov and his colleagues were forced to stop the experiment for ethical reasons.

The success of this procedure, as scientists believe, will improve the reputation of CRISPR/Cas9 and other methods of editing the genome that is being developed today. It’s not clear whether it is possible to apply this procedure to «fix» other mutations in human DNA, but scientists hope that they can be addressed in a similar way.

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