Release date: 2017-08-14
Today, Science publishes a heavyweight study online. The team from Zhejiang University, Yunnan Agricultural University, Chongqing Third Military Medical University, Harvard University and other research institutions and companies used the CRISPR-Cas9 gene editing technology to solve the key problem of transplanting pig organs into the human body. The author of the study was 2017 Global Youth Leader, and Dr. Yang Wei, a post-80s scientist.
Organ transplants affect the lives of millions of people around the world. Take the United States as an example. At this moment, the number of patients waiting in line for organ transplantation is as high as 120,000. However, the number of organs that can be used for transplantation each year is very limited, and there are only 30,000 successful organ transplants. It is estimated that in 2016, 22 patients die every day while waiting for an organ transplant.
We are delighted to see that many researchers from China have participated in this heavy research (Source: Science)
In the 1990s, medical researchers tried to solve this problem. The strategy they give is xenotransplantation, which is transplanted into animal organs in humans. In these animals, the organs of pigs are similar in size and function to human organs, and thus have attracted the attention of researchers. However, the pig's genome contains sequences of endogenous retroviruses (PERV) that pose potential health risks to humans. Direct transplantation of pig organs into the human body may lead to the spread of new diseases. Scientists have been trying to solve this problem for decades.
CRISPR-Cas9 technology is expected to solve the challenges faced by pig organs for xenotransplantation (Source: eGenesis official website)
The emergence of the CRISPR-Cas9 gene editing technology has allowed scientists to see the dawn. On the one hand, it can accurately remove the PERV sequence in the pig genome and reduce the risk of infection in humans; on the other hand, it can even reduce the body's strong immune response to pig organs. “In the past, these obstacles were insurmountable,†said Dr. Yang Wei. “But now, with gene editing technology, we are expected to solve these two problems at the same time.â€
The strategy adopted in this study (Source: eGenesis official website)
In today's "Science" paper, the researchers confirmed the feasibility of this idea. Using CRISPR-Cas9 technology, this multinational team succeeded in inactivating all PERV sequences in the porcine primary cell line! Subsequently, they used "cloning technology" (somatic cell nuclear transfer technology) to breed pig embryos and transplanted them into surrogate sows. Subsequently, they examined genomic DNA and mRNA levels in the born piglets, confirming that the PERV sequence continued to be inactive. In other words, the key safety hazards of transplanting these pig organs into the human body have been successfully solved.
“Before our research, the survival of these genetically modified pigs is very uncertain in science,†said Dr. Yang Wei. Today, we no longer need to worry about this.
Piglets with inactive PERV sequences have been successfully born (Source: eGenesis official website)
Limited by the cloning technology itself, the probability of a successful piglet being born is only about 1%. But the good news is that gene editing does not reduce the success rate of cloning technology. The 1% probability is also operative in application. At present, 37 piglets have been born using this method. In all piglets, PERV is inactive.
“If the transplant of pig organs is safe and effective, this will greatly change the face of organ transplants,†Dr. David Klassen said. He is the chief medical officer of a non-profit organization that manages the entire US organ transplant system.
After solving the security risks caused by PERV, the researchers plan to challenge the next challenge. As planned, they will knock out genes in pig organs that cause a strong immune response in humans and insert genes that prevent potential toxicity.
Professor George Church, a well-known geneticist at Harvard University, believes that within two years, we can see the practical application of this breakthrough (Source: Evolution News)
Dr. Yang Wei’s mentor, Professor George Church, a well-known geneticist at Harvard University, also participated in the study. He is optimistic that this breakthrough is expected to achieve the transplant of pig organs to the human body within two years. In the future, we are expected to provide liver, kidney, lung, heart and other organs to a large number of patients, and even provide new pancreas for diabetic patients. Every day, 22 patients die while waiting for an organ transplant. Being able to save these patients is a matter of merit.
Reference material
[1] Inactivation of porcine endogenous retrovirus in pigs using CRISPR-Cas9
[2] CRISPR slices virus genes out of pigs, but will it make organ transplants to humans safer?
[3] Gene Editing Spurs Hope for Transplanting Pig Organs Into Humans
Source: Academic Jingwei
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