A team of researchers from the Guangzhou Medical University has used the CRISPR gene editing technique to edit human embryos in an attempt to immune them from the HIV virus.
Researchers try to alter or make a mutation into non-viable human embryos, that were lately destroyed after three days. The team emphasized the attempt of modification was made in embryos that couldn’t result in a live birth.
Yong Fam, author, and worker at the Medical University in China, with his team of scientists, collected a total of 213 fertilized human eggs between the months of April and September of 2014.
The eggs were donated by 87 patients who ended up being unsuitable for an in vitro treatment in a fertility therapy, because of the extra set of chromosomes they contained.
CRISPR Technique
Clustered regularly interspaced short palindromic repeats or CRISPR are segments of prokaryotic DNA. The set contains short repetitions based in sequence, each one of the repetitions in the DNA is followed by “Spacer DNA” from different exposures to viruses or plasmid.
This technique provides researchers the opportunity to create an immune system that resists a foreign genetic element, such as plasmids or viruses.
The CRISPR technique through its spacers recognizes and cuts the endogenous genetic elements. Allowing its application in the altering of human, animal and other organism’s germline.
Since the discovery of the technique, numerous ethical concerns have been issued in the modification of human germline.
The attempt in the study
According to the study first published in the journal Nature, the team tried to evaluate the precise methods in the modification of human embryos. Trying to introduce a mutation that could have prevented people from suffering HIV virus.
The mutation was attempted in an immune cell called CCR5, this protein is found on the surface of white blood cells involved in the immune system.
CCR5 cells are the first cells that HIV attempts to enter and infect, certain humans carry a mutation of the CCR5 denominated CCR5Δ32. That protects them from the HIV Virus.
The researchers team was trying to modify the CCR5 cell into the CCR5Δ32 mutation, to create human embryos naturally resistant to HIV.
The study didn’t reach any conclusions, since the human embryos tested had been rejected by in vitro clinics because of their extra set of chromosomes, making it a little more difficult to determine if this procedure will result in healthy human embryos.
The results of the study
In the attempt of modification, the 45 embryos at the one-cell stage were treated with the CRISPR technique, containing instructions to develop the CCR5 mutation.
Of the 45 injected embryos, only 26 developed into eight- cell embryos and only four had the CCR5 mutation. Nonetheless, these had only one copy of the CCR5 gene, it wasn’t enough to resist the HIV virus.
Although the genes didn’t develop the desire correct mutation, the team didn’t find any mutations in other parts of the embryos while using the CRISPR technique.
A stem-cell biologist in Massachusetts Children’s Hospital, George Daley told Scientific American his thoughts on the paper.
“ This paper doesn’t look like it offers much more than anecdotal evidence that it works on human embryos, which we already knew. It’s certainly a long way from realizing the intended potential” Said Daley in a statement.
Previous Embryo Studies
A number of placed researches have been made in the attempt to modify a human embryo or a human gene. Mostly to make them HIV-resistant.
Four clinics in the USA recruited patients suffering from the HIV virus to treat them with a gene editing technique in which they tried to destroy the CCR5 gene in which the HIV assembles.
Another Chinese research team had announced previously in April 2015, an attempt to modify a human gene linked to a blood disease. The study was also dismissed because of the non-valid human embryos.
Moral and Ethic Disputes
A lot of ethical statements and opinions have been made in the gene-editing business, even though local committees have approved the experiments as well as the patients who donated their embryos.
A bioethicist in Hokkaido University at Sapporo Japan tells Scientific American “ Introducing CCR5 modification and trying to repair, even in non-viable embryos is just playing with human embryos” Said Tetsuya Ishii to the website.
Although all of these experiments are only being made in a preliminary way, it opens wide the door for human gene-editing and possible, yet futuristic, cures for the diseases humans suffer today.
Source: Scientific American