On the same rake

The Chinese tried to get HIV-resistant embryos using genome editing

Roman Fishman, N+1

Chinese biologists have made a new attempt to use the CRISPR/Cas9 system to edit the genome of human embryos, trying to make changes to it that make T-lymphocytes resistant to HIV infection. Despite the low percentage of successful mutations, the authors consider the experiment successful, the results of which are published in the Journal of Assisted Reproduction and Genetics (Kang et al., Introducing precise genetic modifications into human 3PN embryos by CRISPR/Cas-mediated genome editing).

Yong Fan and his colleagues at Guangzhou Medical University used zygotes that were prepared by doctors for IVF procedures, but were rejected due to a serious violation of the karyotype (the number and characteristics of their chromosomes). Such anomalies often occur during artificial insemination and can lead to the appearance in zygotes of three "protonuclei", pronuclei, each containing one haploid set of chromosomes. Trypronuclear (3PN) zygotes develop into embryos with a triploid genotype, and implantation of such embryos always develops pathologically, so doctors do not use them.

Having received 3PN zygotes, scientists used CRISPR/Cas9 authors to make changes to the genes located on the third chromosome and encoding the CCR5 receptor. This protein is located in the membrane of T-lymphocytes and some other cells of the immune system and is used by HIV to penetrate them. There are cases of the natural occurrence of such mutations (CCR5Δ32): a heterozygous state dramatically reduces the likelihood of HIV infection of the cell, and a homozygous one may completely exclude such a possibility.

Of the 26 3PN zygotes subjected to the procedure, the altered CCR5Δ32 allele appeared in only four, and even then not in all copies of their third chromosome: they remained either of the original "wild" type, or received accidental changes made by mistake. American biologist George Daley, commenting on these results for Nature, noted: "It seems that the work contains nothing but anecdotal evidence that the technology also works on human embryos – which we knew perfectly well before."

Almost exactly a year ago, another team of researchers from China published the results of the first attempts of such editing of the globin beta chain gene in living human embryos. And although the procedure went wrong in the vast majority of embryos, this work stimulated a broad discussion about ethics and the need for further experiments in this area. In February 2016, such studies were officially allowed in the UK.

Portal "Eternal youth" http://vechnayamolodost.ru  11.04.2016