Over one hundred thousand people within the United States are on the national transplant waiting list desperately in need of a kidney. With this shortage comes about twelve deaths each day. Scientists and doctors have been trying to find out an ethical and effective way to solve this organ shortage. As of October 22, 2021, surgeons in New York City have successfully attached a pig kidney to a human that wasn’t immediately rejected by the host human. This is a huge step in modern medicine to help those who die waiting for an organ they need. This article was chosen because I signed up to be an organ donor when I got my license and believe that other people should have the chance at a second life.
According to Science News, the article titled, “What does the first successful test of a pig-to-human kidney transplant mean?” walks the reader through the scientific and moral considerations that come with this medical breakthrough (Lambert). The process of xenotransplantation describes any procedure that involves transplantation into a human from a nonhuman source (Center for Biologics Evaluation and Research). Pigs were chosen due to how anatomically similar their organs are to humans as they have all the same thoracic and abdominal organs. They also are able to be bred in a highly controlled manner, which is important if mass production of these organs will be necessary in the near future.
The immediate reaction that occurs following a xenotransplantation is called a hyperacute rejection. It can be described as the most severe and violent immunological reaction that occurs within the first 24 hours that results in loss of function and death of the organ (Hyperacute graft rejection). In recent years, scientists have discovered that this aggressive immune response is brought on by antibodies that detect a specific sugar molecule that dots pig blood vessels, called alpha-galactose or alpha-gal for short. This sugar molecule is also responsible for some allergic reactions to red meat. Scientists figured out how to disable the pig gene that is responsible for producing this sugar in the early 2000s but only recently have produced successful results.
Figure 1: Structure of Alpha-1, 3-galactose
Alpha-1, 3-galactose is a carbohydrate found in most mammalian membranes except for humans and primates. While there have been some known breakthroughs when it comes to Alpha-gal syndrome (AGS), the mechanism of action for alpha-gal is still unclear and requires further research. It has been found that a bacterial alpha-galactosidase efficiently can remove linear alpha-gal ends from target molecules.
Figure 2: Stepwise process of xenotransplantation
The FDA has also recently approved altering the gene that produces alpha-gal for those who can’t eat red meat to produce a new “breed” of GalSafe pigs (Commissioner). These pigs are created by modifying the target gene (GLA) by eliminating gene expression in a pig embryo. This modified embryo is then implanted inside the surrogate sow who will deliver piglets with modified immune systems more compatible with humans. When the pig kidney is removed from the adult swine, the pig’s thymus is also removed with it and attached before attaching to the host human. This is an important step because the thymus gland can help educate the human’s immune system to recognize the kidney as part of the body. Lastly, the thymus-kidney system is surgically connected to the organ recipient on their thigh so that the doctors can oversee the kidney function outside of the body.
The ethical considerations when it comes to operating on humans in this manner is always going to be up for debate. The family of a woman who was pronounced brain dead but kept alive on a ventilator gave consent for this procedure to take place. The woman wanted to be an organ donor but in the state that she was in, was unable to donate her organs. The family believed that she would have approved of possibly giving the gift of humanity to other people in another way. The doctors attached a pig kidney with the absence of the alpha-gal sugar as well as its thymus gland to the woman and monitored normal kidney function. The kidney produced urine and showed other signs of normal functioning for 54 hours before the procedure was terminated due to guidance provided by ethics reviewers.
Sources
Center for Biologics Evaluation and Research. (2021, March 3). Xenotransplantation. U.S. Food and Drug Administration. Retrieved October 26, 2021, from https://www.fda.gov/vaccines-blood-biologics/xenotransplantation#:~:text=Xenotransplantation%2 0is%20any%20procedure%20that,nonhuman%20animal%20cells%2C%20tissues%20or. Commissioner, O. of the. (n.d.). FDA approves first-of-its-kind intentional genomic alteration in line of domestic pigs for both human food, potential therapeutic uses. U.S. Food and Drug Administration. Retrieved October 26, 2021, from https://www.fda.gov/news-events/press-announcements/fda-approves-first-its-kind-intentional-geno mic-alteration-line-domestic-pigs-both-human-food. Hyperacute graft rejection. Hyperacute Graft Rejection - an overview | ScienceDirect Topics. (2014). Retrieved October 26, 2021, from https://www.sciencedirect.com/topics/medicine-and-dentistry/hyperacute-graft-rejection#:~:text=H yperacute%20rejection%20refers%20to%20the,within%20a%20period%20of%20hours. Lambert, J. (2021, October 22). What does the first successful test of a pig-to-human kidney transplant mean? Science News. Retrieved October 26, 2021, from https://www.sciencenews.org/article/xenotransplantation-pig-human-kidney-transplant.
Effective title and opening graphic. Your first paragraph puts the problem and the possible solution right up front making it an effective "lede" paragraph. Your second paragraph appropriately gives your source and justifies your title by explaining why pigs were chosen as an organ source. YOur third paragraphs identifies the primary scientific problem with donation of pig organs to humans helping us understand the development that the news article reports. The last sentence in this paragraph is a little unclear. Does "successful results" mean disabling the gene or producing pigs without the sugar in question. In the next paragraph it is not entirely clear what the AGS is. Is it the red meat allergy mentioned previously? The alpha-gal structure provides some scientific legitimacy to your post even if the general reader would not recognize it as a disaccharide. The explanation of the actual transplant procedure is good and concise. The figure helps. I note that while "Science News" is addressed to the general reader it is not really a general interest site like a newspaper, news magazine or news broadcast network site or other widely read general interest sites. Overall an effective post on an interesting and important topic.
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