CRISPR–Cas9基因技术 z-bio 2021-08-04 300

　　Shaanxi Province in western China is famous for its rugged and weathered landforms, coal and wool. When it comes to this province, the first thing you think of is scientific research. However, at the Shaanbei Cashmere Goat Engineering Technology Research Center in Shaanxi Province, scientists have just bred a new goat breed, which has stronger muscles and longer wool than ordinary goats. This kind of goat was not bred, but obtained by directly manipulating animal DNA-which also signifies that China is rapidly joining the genetic modification revolution that is sweeping the world.

　　Geneticist Qu Lei hopes to improve the income of shepherds by increasing goats’ lamb and wool production. Qu Lei’s colleagues said that they have conducted many years of research in the laboratory in Yulin and have not made much progress. Qu Lei’s research assistant Zhu Haijing wrote in an email: “Although we have carried out research for many years, the results are not so remarkable.”

　　When researchers started to use the new gene customization technology CRISPR–Cas9, the situation changed. CRISPR-Cas9 is a genetic modification technology developed in the United States three years ago. It uses enzymes to precisely locate and cut DNA fragments, just like a word processor can search for and delete specified phrases-this process is called " Gene editing". Although CRISPR-Cas9 is not the first tool used by scientists to modify DNA, it is by far the most accurate and cheapest technical method. Now, the ease of use of this powerful technology has brought attractive possibilities for scientific research, but also caused urgent ethical issues.

　　When Qu Lei’s goat research team began to use CRISPR technology, they made rapid progress. In September this year, Qu Lei and 25 other Chinese co-researchers published their research results in Scientific Reports (published by Nature Group). They successfully knocked out two genes that inhibit wool and muscle development in early goat embryos, resulting in 10 baby goats with stronger muscles and longer wool. So far, these custom goats have not shown any abnormalities. "We believe that after the safety and reliability of genetically modified livestock are confirmed, this new breed will be promoted and commercialized breeding will begin," Qu Lei predicted. He believes that this work will be a simple way to increase the sales of mutton and woolen sweaters in Shaanxi.

　　This research is just one of a series of papers recently published by Chinese scientists on CRISPR-modified animals (including goats, sheep, pigs, monkeys, dogs and other mammals). For example, just in October this year, Chinese scientists published a study on breeding beagle dogs with abnormally developed muscles in the Journal of Molecular Cell Biology. This research received financial support from the National Natural Science Foundation of China, the Ministry of Agriculture, the Ministry of Science and Technology and the provincial government.

　　In Beijing and other research centers and other local areas, even if there are not hundreds, there are dozens of Chinese scientific research institutions using CRISPR technology to conduct research in full swing. Hu Minhua, a geneticist at the Guangzhou General Medical Research Institute, said: “This is the research focus of the Chinese Academy of Sciences.” One of his colleagues, Lai Liangxue of the Guangzhou Institute of Biomedicine and Health, added: A lot of funding has been invested in research on genetically modified animals."

　　This has caused many people to worry about ethics and worry about creating new forms of life. Unlike previous gene therapy, the modification of fertilized eggs or embryos using CRISPR technology is "permanent"-that is, what this technology changes is heritable DNA. Scientists usually succeed in transforming a fertilized egg or embryo after tens or hundreds of failures. But technology is advancing rapidly. George Daley, a stem cell biologist at Harvard Medical School, said: "The difference between CRISPR technology lies in its high efficiency, so this technology is more likely to be widely adopted." It was previously used for manipulation. The methods of the genetic code of life are very inefficient, complex, and the results are difficult to predict. He said: "Because CRISPR technology is very effective, so we began to worry about its ethical issues."

　　This kind of ethical problem exists in all experiments that use CRISPR technology to "edit" plant and animal DNA-if scientists like Qu Lei continue to improve this technology, it may appear in humans in the future. "As with any genetic intervention, there is always a trade-off between human welfare and animal welfare, while also considering the impact on the environment." Daley said of the livestock "improvement" that the China Institute of Gene Editing is concerned about. . Regarding the more complex topic of possible human CRISPR experiments, he proposed: "Which medical research and applications are allowed and which should be strictly prohibited? Can we draw a clear line between the two? ?" Finding an answer that the world can generally agree with will be the next problem for geneticists and ethicists.

　　China is not the birthplace of CRISPR technology (there are still patent disputes between scientists at MIT and the University of California, Berkeley). However, thanks to the rapid growth of scientific research funding and the large scale of scientific research institutions (mostly affiliated to the country), Chinese scientists have adopted CRISPR technology extremely quickly. According to the Science, Technology and Industry Outlook 2014 published by the Organization for Economic Cooperation and Development, between 2008 and 2012, China's scientific research expenditures doubled. (The report pointed out that China’s research funding is currently ranked second in the world and will surpass the United States in 2019.) Despite China’s strength, “it is still a rising star in the international scientific community and lacks the same institutions. "Censorship tradition," Daley said. Scientists in the United States and Europe are paying close attention to how Chinese scientists will use such powerful tools.

　　George Church, professor of genetics at Harvard Medical School, said that the current level of difficulty and level of research using CRISPR in China is "comparable to the United States and Europe." An analysis conducted by Thomson Reuters' Thomson Innovation department found that more than 50 Chinese research institutions have applied for gene editing patents.

　　Like the United States and the United Kingdom, some experiments conducted in China are aimed at realizing potential biomedical applications. For example, scientists at the Yunnan Key Laboratory of Primate Biomedicine use CRISPR technology to promote the neurodevelopment of monkeys to test whether it is feasible to build primate disease models. Such animal models can be used to better understand autism and mental health. Human diseases such as schizophrenia and Alzheimer's disease. For cashmere goat research and similar experiments to knock out the muscle growth inhibitor gene in sheep, the purpose of this type of research is to transform the animal husbandry-more muscular livestock can meet the rapidly growing meat demand of the Chinese middle class.

　　But it was the recently released world's first human embryo gene editing experiment that caused China to attract widespread international attention or criticism for the first time. In April of this year, a Chinese research team published a paper online in the Protein & Cell journal. They tried to use CRISPR technology to transform non-viable human embryos (these embryos were obtained from a fertility clinic with permission). Criticism and worry. Their research goal is to delete β-thalassemia-related genes without causing other mutations, but this experiment failed after trying on 85 embryos.

　　China prohibits experiments on human embryos over 14 days old, so this type of research is legal, and it is even supported by some government funds. (Most states in the United States do not prohibit such research, but may not be eligible for federal funding.)

　　Many international observers have made sharp accusations about this, believing that Chinese scientists have bad intentions. Marcy Darnovsky, executive director of the Center for Genetics and Society, a California non-profit organization, commented on this report as follows: “Researchers dare to violate international recognition on the moral level to transform the human germ cell line.” Some are very good. News organizations with the right to speak have adopted negative headlines, such as "Chinese Scientists Editing Human Embryo Genes to Arouse Concern" in The New York Times and "Edit Humans" in The Economist.

　　Daley stated that since China has first joined the international scientific research arena, its institutional norms for approving research projects are not completely transparent. In addition, researchers are not the heads of world-renowned scientific research institutions. For those well-known scientific research institutions, such as the Broad Institute of MIT and Harvard University or the Francis Crick Institute in London, the scientific community understands them and also Understand their research motivation. Daley stated that China's scientific research institutions are "responsibly strengthening discussions on this issue."

　　This kind of argument may be excessive. Chinese scientists say they have never tried to edit human germ cell lines or develop clinical applications. Huang Jun, a geneticist at Sun Yat-sen University and co-author of the human embryo paper, wrote in an e-mail that "it is forbidden to edit germ cell lines in the clinic." But he believes that future CRISPR experiments may help the research of human diseases. "Scientists can use CRISPR-Cas9 technology to learn more about the true function of some key genes in the preimplantation stage of human embryos... We can also clarify the mechanism of gene repair, which will promote the onset of early developmental genetic diseases. The mechanism gains a new understanding."

　　The Church of Harvard University said that subsequent evaluations recognized the rigor of the methods used in human embryo experiments in China, including deliberately choosing to use non-viable embryos that are unlikely to develop into babies. But the uneasiness caused by the experiment reflects the seriousness of such research risks and the public's concern about whether Chinese scientists accept the same ethical principles as the West.

　　In early December, scientists from the United States, the United Kingdom and China will meet at the National Academy of Sciences and reach an international agreement on DNA editing of human germ cell lines. Church participated in preparatory meetings between Chinese and American counterparts. He believes that the focus of these meetings is not to accuse China of ethical derailment, but the urgent need to openly discuss and clarify the guidelines for human germ cell experiments. "I think China has the same sense of responsibility as other countries. I don't think there is a problem in China. The behavior of Chinese scientists is not problematic in the legal systems of most countries, but I think there was no consensus at the time. There may be some Some misunderstandings," he said. "I think it is necessary to talk about it. Everyone wants to have the opportunity to discuss this topic-sometimes you need an opportunity to make this issue more reportable."

　　Although scientists have put forward a series of opinions on what kind of experiment is acceptable, the essential difference is not the difference between the East and the West. In September, according to a statement from the Francis Crick Institute, Kathy Niakan, a researcher at the institution, submitted an application to the British regulatory agency to try to "use the new CRISPR gene editing technology to conduct experiments in human embryos." "The research carried out by the Creek Institute will only be used for scientific research purposes and will not develop clinical applications. However, the results obtained from this research will be of great significance to the understanding of the healthy development mechanism of human embryos."

　　At the same time, Chinese scientists pointed out that there are also disputes over the ethical issues of DNA editing in China.

　　Zhao Yaofeng, a geneticist at the State Key Laboratory of Agricultural Biotechnology at China Agricultural University, said that regardless of the outcome of the discussions held in Washington, there are also fierce debates on ethics and safety regarding CRISPR experiments in agriculture and biomedicine in China. He said: "I think people currently hold different views on the issue of genetic modification, even in China. There are different opinions even in China. Some members of the public are afraid of this, but in the academic world, I think most scientists support this type of research—— We need to think about the future." As an expert on cashmere goats, Zhao Yaofeng does not believe that genetically modified mutton will quickly become a Chinese meal like Qu Lei. "If you want to promote genetically modified animals in the agricultural field, you must consider the opinions of the public-can they accept this kind of food? Even if this technology is very safe, if you want to commercialize this kind of mutton in agriculture, you must also consider A variety of factors.” There are precedents in China before. The Chinese government has invested a lot of money in research on the improvement of genetically modified crops, including corn, wheat, and rice. However, due to the public’s resistance to this, the commercialization has been delayed.

　　Whether it is China or any country, the development of scientific research in certain fields is faster than the formation of laws and regulations, so there may be individual laboratories or scientists who violate consensus to conduct research. At the Shenzhen International Biotechnology Summit held on September 23, private gene company and industry giant BGI announced that it would launch gene-edited miniature pigs for sale as pets; these miniature pigs were originally bred for biomedical research purposes. Li Yong, technical director of BGI's genetic animal science platform, rejected the request of "Scientific American" to interview micro pigs, but he had previously stated in "Nature" that he would "assess the market." (Compared to agriculture, pets are not regulated so strictly and will not be supplied to the domestic market.) Some Chinese researchers explicitly objected. Lai Liangxue, the co-author of the Beagle research paper, said that he believes that scientists “should not use CRISPR technology to create pet breeds with special qualities to meet the special preferences of pet owners”.

　　Lai Liangxue’s own research does not involve human embryos, but he puts forward his own point of view on the upcoming larger controversy: If the safety and efficiency issues can be solved first, he is open to future therapeutic applications, but not Support eugenics application. "CRISPR technology can be used to correct mutations that cause genetic diseases in humans, and should not be used to create special traits that some people seek." Other Chinese scientists who use CRISPR to carry out research expressed similar views on this, but no one is concerned about the future. The CRISPR application makes predictions. Huang Jun said: "Gene editing technology is very popular all over the world."

　　Church said that public debates about all powerful new technologies reflect pre-existing public expectations and fears. The debate on CRISPR technology includes the desire to eliminate genetic diseases, as well as concerns about the commercialization of human reproduction, the exclusive privileges of the rich, and the rise of China.