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The British join in the fun: What is the debate on human germ cell genetic editing?

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Injecting a gene editing system into the embryo by microinjection


Author | Ye Shui, leaf water to send

Editor | Li Xiaoming

Intellectuals for a better intellectual life ID: The-Intellectual

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Recently, the global use of the gene editing technology CRISPR/Cas9 to study human early embryos has emerged.

On August 3, the research team led by Shoukhrat Mitalipov, director of the Embryonic Cell and Gene Therapy Center at Oregon Health Sciences University (OHSU), successfully repaired a disease-causing gene mutation in human embryos - the MYBPC3 gene mutation - which causes myocardial damage Thickening, which may lead to heart failure or sudden death.

Last week, Kathy Niakan, a researcher at the Francis Crick Institute in London, UK, used the CRISPR/Cas9 gene editing technology for the first time to study OCT4 , a key gene in the early development of human embryos . They found that OCT4 is critical in the early development of embryonic cells and determines the process of differentiation from embryonic 4 cell stage to 8 cell. If this gene is deleted, the embryo will not develop into normal blastocyst (Blastocyst), further development. affected.

These efforts reveal the mystery of early embryonic development and raise questions from peers: developmental and genetic biologists have commented that OCT4 is readily confirmed in mice during early embryonic development, while human embryos are used in science. The meaning is small – although British researchers believe that OCT4 plays a different role in mouse and human embryos – it is striking, mainly because of its ethical shock, not scientific discovery. Nor is it a technical invention.

The broader topic of discussion is: Is it necessary to use human embryos in these studies that are being published? Has the era of human early embryos been studied using the gene editing technology CRISPR/Cas9? How can relevant scientific research be incorporated into a universally agreed human ethical norm?

"Editing work on the genome of the human germ cell will appear (perhaps already, but the article has not yet been published), and researchers are responsible for ensuring that the technology is safe and effective." September 24, at the Frontier Forum on Genetic Editing Science and Technology Dana Carroll, a member of the American Academy of Sciences and a molecular biologist at the University of Utah, said at the inaugural meeting of the Genomics Editing Branch of the Chinese Society of Genetics.

How does CRISPR/Cas9 modify human embryonic genes?

Flow chart of early development of human embryo

In a study by British scientists, the researchers found that 50% of the unmodified OCT4 embryos in the control group were able to form blastocysts normally, while only 19% of the OCT4- deficient embryos developed normally.

The embryos studied were from couples who had had assisted reproduction (IVF) and had 58 embryos. The study was approved by the British Human Fertilization and Embryology Authority (HFEA). Even so, it will still be the focus of hot discussion.

In fact, basic research on genetic editing of human early embryos has been around two years ago. In 2015, Huang Jun, an associate professor at Sun Yat-Sen University, and the collaborators took the lead in genetic editing of 86 discarded human embryos, attempting to transform genes related to thalassemia in fertilized eggs. At that time, it was found that CRISPR/Cas9 technology was off target, and related papers were published. " Protein & Cell " was the only study that edited and published the genome of human embryonic cells at the time, sparking concerns about genetic editing technology to transform embryos, and intense discussions among scientists around the world. .

On September 23 this year, "Protein and Cell" re-released Huang Jun's follow-up study on the team: they used a single-base editing system to repair mutations in the HBB-28 gene associated with thalassemia in the human embryonic genome. The single base editing method consists of a variant of CRISPR-Cas9 and cytosine deaminase, which directs the correct DNA position by targeting RNA and replaces guanine (C) with thymine (T). This method of genetic correction does not cause random DNA deletions and insertions because of the specificity of the repair.

"From the results, this single base editing method can still perform accurate repairs more efficiently." In the frontier forum of genetic editing science and technology, Huang Jun said.

Huang Jun was confirmed to be in compliance with China's laws, regulations and ethical regulations in 2015, but with the wide application of CRISPR technology, the international scientific community has no circumvention of the safety and ethical issues of human genetic editing technology. .

In December 2015, the International Summit on Human Gene Editing, co-organized by the National Academy of Sciences, the National Academy of Medicine, the Chinese Academy of Sciences, and the Royal Society of the United Kingdom, was held in Washington, DC, from scientists in the field of genetic editing. Policy makers and ethicists discuss the research breakthroughs, potential applications, and the social and regulatory issues that may result from genetic editing techniques.

In February 2017, following the international consensus of the Human Genome Editors International Summit, the American Academy of Sciences and the American Medical School published a book entitled " Human Genome Editing: Science, Ethics, and Governance" . Reported a red line on the genetic editing of human germ cells. In this report, we have affirmed the role of gene editing technology in the exploration of basic life processes by scientists, and also set strict conditions for the clinical application of the technology. The report mentions that human germ cells can be genetically manipulated under strict supervision to treat human genetic diseases such as sickle cell anemia and cystic fibrosis, but genetic modification such as height, appearance and even intelligence for non-medical needs. Strictly prohibited.

In China, the regulations, laws and regulations on human germ cell gene editing are still blank. At present, the Ministry of Science and Technology and the Ministry of Health issued the "Ethical Guiding Principles for Human Embryonic Stem Cell Research" in 2003. Zhou Qi, an academician of the Chinese Academy of Sciences, said in an interview with the Science Bulletin in early 2016 that although China is one of the sponsors of the International Summit of Human Genome Editing in Washington, it should also abide by the consensus of the conference, but this international consensus does not have laws. The effect, therefore, the core issue for the supervision of genetic editing technology is to "develop the regulations, laws and regulations of their respective countries as soon as possible".

The aforementioned developmental and genetic biologists commented on this topic: Human germ cells should not be genetically altered, which is considered the red line of scientific research. After the red line was first broken by the Yellow Army, some scientists in the United States and the United Kingdom believed that this red line setting would no longer make sense in the face of fierce international competition, and even rushed to make different genetic modifications and changes to human germ cells. Ignore the significance of research on changing genes. What brings in the scientific world is clear flow or turbidity, which is worthy of observation.

At present, the application of gene editing technology to the treatment of human diseases is the focus of researchers. Ji Weizhi, Distinguished Professor of Kunming University of Science and Technology and Director of the Center for Translational Medicine of the Primate, said at the meeting on the 24th that it is necessary to conduct an assessment of safety and effectiveness. “Like drug development, certain procedures are needed to ensure its safety. Sex and effectiveness."

"Intellectuals" learned at this meeting that relevant discussions are still going on. Scientists from institutions such as the Chinese Academy of Sciences are discussing with relevant government agencies how to formulate appropriate regulations and applications for such technologies. This has become the current genetic editor. One of the focus topics of concern.


Note: This video and some of the images are open to the news media by Kathy Niakan.


Reference materials:

  1. Ma, Hong, et al. "Correction of a pathogenic gene mutation in human embryos." Nature 548.7668 (2017): 413-419.
  2. Fogarty, Norah ME, et al. “Genome editing reveals a role for OCT4 in human embryogenesis” Nature (2017). doi:10.1038/nature24033
  3. engine.scichina.com/pub


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Intellectuals for a better intellectual life ID: The-Intellectual