The U.S. approves for the first time gene-edited pigs that can both be edible and produce drugs on the market
Are allergic to meat only vegetarian? Genetic engineering technology allows you to eat meat with confidence
Our reporter Ma Aiping
The gene-edited pig "GalSafe Pig" developed by the American medical company Revivicor was approved by the U.S. Food and Drug Administration (FDA) on December 14. It is edible and can be used to produce medical products.
Scientists have used genetic engineering methods to knock out the protease that adds alpha-galactose (Alpha-gal) to the surface of pig cells, so that ordinary people who are allergic to meat can safely eat this gene-edited pig.
In addition, "GalSafe pig" can also be used to produce drugs similar to heparin, and its tissues and organs may potentially solve the problem of immune rejection after xenotransplantation of patients.
"'GalSafe pig' was approved for listing, marking the first time that a gene-edited animal has achieved dual use for food and medicine." Jiang Tao, a senior engineer at the Biology Research Center, Institute of Genetics and Development, Chinese Academy of Sciences, said in an interview with a reporter from the Science and Technology Daily.
A variety of gene-edited animals have been approved for marketing
The first approval of a genetically modified animal for both food and potential biomedical use is a huge milestone in scientific innovation.
The FDA currently determines that the meat of this gene-edited pig can be safely consumed by the general population.
This is the first time the FDA has approved genetic changes in animals for human food consumption and potential therapeutic use. It is also the FDA once again approved a gene-edited animal for marketing after it approved gene-edited salmon in 2015.
Which gene-edited animals have been approved by the United States and other countries?
Jiang Tao pointed out that there are several gene-edited animals approved by developed countries in foreign biotechnology.
In 2009, the FDA approved a gene-edited goat worth tens of millions of dollars on the market, but not for food, but as a bioreactor, using its mammary glands to produce a protein drug that prevents blood clots, and then secreting it from the milk to treat humans Hereditary antithrombin deficiency.
In 2014, the FDA approved the marketing of a gene-edited rabbit that can be used to produce drugs for the treatment of hereditary angioedema.
"In 2015, a gene-edited chicken developed by the Rosslyn Institute in Cambridge, UK, which can produce recombinant protein drugs in eggs was approved by the FDA for the treatment of human genetic diseases that cannot degrade cell fat. In the same year, the growth rate and feed rate of return The gene-edited salmon, which is significantly better than ordinary Atlantic salmon, became the first gene-edited animal approved for consumption by the FDA and relevant Canadian authorities.” Jiang Tao said.
Remove the corresponding genes to truly prevent allergies
GalSafe means galactose safe. "GalSafe pig" is named after the lack of "α-galactose" molecules on the surface of body cells.
Alpha-galactose exists only in mammals, but not humans.
In daily life, some people can cause allergies after eating meat containing α-galactose.
"GalSafe pig" does not contain α-galactose, so it can not only provide safe meat for allergy sufferers, but also can be used to produce drugs for allergy sufferers, such as heparin, a blood thinner without α-galactose.
Why can we prevent allergies only by knocking out related genes? Can we avoid allergies through cooking?
In this regard, Jiang Tao explained that some foods cause allergies after human consumption, indicating that allergen molecules or parts of the food in the food bind to the special immune receptors of human intestinal epidermal cells, triggering a type of acute stress response.
"Such allergic conjugates have often been partially digested by various digestive enzymes in the gastrointestinal tract, gastric juice, pancreatic juice, and intestinal juice. They can still maintain the necessary structure and sufficient quantity. This is often also not destroyed or completely eliminated by ordinary cooking. Yes, so the most thorough solution is to completely remove the corresponding gene, which is to use genome editing to knock out this gene so that the corresponding allergen will not appear at all." Jiang Tao said.
Tang Bo, Ph.D. in Molecular Biology, China Agricultural University, explained that α-galactose is called α-1,3-galactose. It is widely found on the surface of mammalian cells such as pigs, cattle, and sheep, but in humans and non-human primates. Not on the cell.
Some people may have mild or severe allergic reactions to red meats such as beef, pork, and lamb that contain α-galactose, which is called α-galactose syndrome.
General cooking methods cannot decompose all α-galactose. People with α-galactose syndrome should try to avoid eating red meat or foods containing red meat.
The breeding conditions of "GalSafe Pigs" are much stricter than those of traditional pigs. In addition, no safety problems of "GalSafe Pigs" have been found.
The FDA also assessed the risk of genomic changes in "GalSafe pigs" of drug-resistant bacteria that endanger human health, and concluded that the risk of eating this type of pork to infect pathogenic bacteria is very low, and "GalSafe pigs" are circulating in the market The number of medium is small, and the related harm can be reduced through continuous monitoring of drug-resistant bacteria.
Medical gene-edited animals cannot be replaced
Since the birth of the first gene-edited mouse in the early 1980s, gene editing technology has developed rapidly, and gene-edited cattle, sheep, fish, and insects have appeared one after another.
Gene-edited animals broke the traditional genetic method of obtaining genes from natural reproduction and became another important turning point in the history of biological development.
Gene editing technology will provide humans with food and medicine with special effects.
The FDA also stated that any institution or research institute must seek further FDA approval before using the "GalSafe pig" for new drugs or human implants.
Although "GalSafe Pig" is not the first gene-edited animal to be approved for marketing, it is the first to be approved to use gene-edited animals for food and medical purposes.
So, which is more important to study gene-edited animals, food or medical use?
"Specific analysis of specific issues cannot simply compare which is more important. At present, there are more researches on medical genetically modified animals, mainly for the production of recombinant protein drugs, human disease models, heterogeneous organ donors, etc. The genetically modified'GalSafe pig' It can be used to produce pork products that are not allergic to people with α-galactose syndrome. The more important use is to produce medical products that are not prone to immune rejection, such as extracting drugs from pigs, xenotransplanted organs, cells and other products "Tang Bo said.
Because it does not contain detectable galactose, "GalSafe pig" may be used as a blood thinner-heparin and other medical products.
The tissues and organs of "GalSafe pigs" may also solve the problem of immune rejection in xenotransplant patients, because α-galactose is considered to be one of the reasons for patient rejection.
Jiang Tao pointed out that gene-edited animals are of great value for both food and medical use, and medical use is an irreplaceable new use.
"Because our food animals have now been intensively reared, and the cost is close to the ceiling. The current genetic modification can improve the feed return rate, lean meat rate, disease resistance, etc.. For medical use, especially the use of special gene-edited pigs as xenogeneic organ transplants The donors of AIDS are an unprecedented new field. Once successfully realized, it is expected to completely reverse the shortage of organs used to treat human organ failure leading to death and save a large number of patients’ lives.” Jiang Tao said.