Porcine gene edits may allow such transplants without rejection.
- A company called Revivicor has received clearance from the FDA to use their genetically modified pigs for medical use or as food.
- The pigs lack genes for alpha-gal sugar, which human bodies reject.
- Revivicor anticipates the first human transplant trials as early as this year.
Waiting lists<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTI2NTc2OC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY3Mjk1Nzk2M30.4ZzZpCgUitKf03AYJeAwIbFCMoaeuEUKnbOexWuar1Q/img.jpg?width=980" id="0349f" class="rm-shortcode" data-rm-shortcode-id="ac2e62bb595a203a6ce81bb646e6e618" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="821" />
Credit: Talaj/Adobe Stock/Big Think<p>The U.S. Health Resources and Services Administration <a href="https://www.organdonor.gov/statistics-stories/statistics.html" target="_blank">says</a> that 109,000 Americans are currently waiting for organ transplants. Seventeen people die each day while waiting, and every nine minutes a new name goes on the waiting list.</p><p>Companies such as Revivicor are hoping to meet this need with <a href="https://web.stanford.edu/dept/HPST/transplant/html/frequently_asked_questions.html" target="_blank">xenotransplants</a>, in which organs from non-human species are transplanted into humans. Scientists have been seeking a way to perform successful xenotransplantation for decades—a newborn referred to publicly as "Baby Fae" rejected a transplanted baboon heart as far back as 1984.</p><p>Ayares says his company is "right on the cusp" of overcoming such rejection issues, anticipating their first transplants may occur in 2021 or 2022.</p><p>Animal tissue may also find use in the formulation of medications.</p>
Rejection<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTI2NTg1OS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYzMzA2Mjc0OH0.pN1W_Vupa5LpYUoq9tHBTQBqRPpdZw6HneRsKmG0vD4/img.jpg?width=980" id="e2d4d" class="rm-shortcode" data-rm-shortcode-id="6675d842b366bec68fc612fbeb380930" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="617" />
Credit: ustas /Adobe Stock<p>The rejection problem stems from the human body's immune system expelling cells from other animals as foreign substances. (Rejection can also be an issue with human-to-human transplants.)</p><p>In 2003, Revivicor began development of GalSafe pigs by removing a gene that appears on the surface of porcine cells, and that produces a sugar called "alpha-gal." It's believed that alpha-gal sugar is the agent that causes the most acute rejections experienced with heart and kidney transplants.</p><p>Alpha-gal is also implicated in a meat food-allergy that occurs after a person is bitten by a Lone Star tick that leaves alpha-gal sugar behind in its victims' skin. Over time, the individual develops an allergy to pork, red meat, and lamb. Revivicor's Gal Pigs may one day be available to such people as non-allergenic pork.</p><p>Revivicor's manipulation of pig genes to support xenotransplantation compatibility doesn't end with eliminating alpha-gal sugar. Today's GalPig carries a total of 10 different genomic modifications—four pig genes have been turned off and six human genes have been introduced.</p>
Tests so far<p>The company, working with the National Institutes of Health, says that they managed to avoid rejection of pig hearts transplanted into baboons for six years, though these didn't replace the animals' own, original hearts. Rather, the pig hearts were transplanted into the abdomens of the baboons simply to assess rejection. Ayares also says GalPig kidneys survived in monkeys for over six months, though it's unclear if they were functioning as kidneys or simply implanted.</p><p>For human trials, Revivicor plans to begin with kidney transplants before attempting heart replacements. They expect to perform these early trials with people awaiting human transplants. XenoTherapeutics of Boston is already testing GalPig skin transplants as a temporary measure for burn victims as their own skin regenerates.</p><p>Other companies are also exploring porcine genetic modifications for xenotransplants, including eGenesis in Boston and its partner Qihan Biotech in Zhejiang, China, who are using CRISPR to perform gene edits.</p>
It's not yet clear why this is happening, but there are plenty of suspects
- A rise in mortality for factory farm pig sows has growers worried.
- There are some obvious possible reasons, but studies are underway.
- Rise in deaths points toward a need for more humane treatment of pigs.
Why are sows dying like this?<p>The cause of the deaths is not altogether clear. The National Pork Board is partnering with Iowa State University on a <a href="https://www.ipic.iastate.edu/news/SowMortalityProject2018.html" target="_blank"><u>multi-year study</u></a> aimed at understanding what's happening. (Iowa's the top pork producer in the U.S.) They intend to collect data on about 13% of food sows on more than 100 farms in 16 states. That's about 400,000 pigs.</p><p>As of now, there are a handful of possible causes that have been suggested:</p> <ul> <li>Vitamin deficiencies</li> <li><a href="http://www.thepigsite.com/pighealth/article/482/mycotoxins/" target="_blank"><u>Mycotoxins</u></a> in feed</li> <li>Overfeeding to promote growth</li> <li>Abdominal issues</li> <li>Overly restrictive confinement systems</li> <li>Overbreeding</li></ul><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8xODY4MTkzMS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYzOTczMzMyNH0.fqaHHJlMjZXXQm8julS9kyhUlY3V-ZWlPkliscJVxwQ/img.jpg?width=1245&coordinates=0%2C138%2C0%2C138&height=700" id="55f71" class="rm-shortcode" data-rm-shortcode-id="ecf4a457f165a4eb3669957bcda2e983" data-rm-shortcode-name="rebelmouse-image" />
A sedentary, crowded existence<p>According to <em>The Guardian</em>, "An estimated 97% of the US's 73 million hogs are raised in closed barns or confined feeding operations." These dense-packed, restrictive environments include gestation and farrowing crates in which sows can barely move, and in which they spend most of their lives. It's a brutal way to exist as pigs have little, if any, opportunity for health-sustaining movement and exercise, and are kept from doing the things pigs like to do.</p><p>Farmer <a href="https://foodtank.com/news/2017/03/paul-willis-interview/" target="_blank"><u>Paul Willis</u></a> tells <em>The Guardian,</em> "I have a neighbor that has been raising pigs [in a confinement system] … and they have a dumpster, and I can go by there almost any time of the day or week and it's full of dead hogs." One company is producing the <a href="https://www.hogslat.com/hercules-arm-pig-hearse" target="_blank"><u>Hercules' Arm Pig Hearse</u></a>, which its website calls "A unique and revolutionary way to effortlessly remove, on your own and in total safety, heavy dead pigs from stalls and haul them away to the designated area." The company adds that the device "has been specifically designed to eliminate any risk of back injury and make work so much easier."</p><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8xODY4MDY3Mi9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyMTgwMzU3Mn0.jKI2IzranQF3WJQ_epUbPWXy8BsFHImJc011qAE9lZs/img.jpg?width=980" id="ac73f" class="rm-shortcode" data-rm-shortcode-id="e75ea22843bb2ce7c21f879094c7dcbd" data-rm-shortcode-name="rebelmouse-image" />
Pigs in gestation crates
Genetic manipulation for more salable pork or more pigs<p>Well-known animal-welfare advocate <a href="https://www.templegrandin.com" target="_blank"><u>Temple Grandin</u></a> of Colorado State University also spoke to <em>The Guardian</em> about this problem, suggesting that shifting pork-industries priorities have wreaked havoc on pigs' bodies.</p><p>In the late 1980s, she points out, pigs were bred for rapid weight gain, more <a href="https://www.thespruceeats.com/what-is-fat-back-fatback-2216903" target="_blank"><u>backfat</u></a>, along with a more lucrative <a href="https://www.thespruceeats.com/pig-diagram-and-pork-chart-995306" target="_blank"><u>loin</u></a>. Later on, though, breeding goals changed as the American diet became more fat conscious.</p><p>Eventually breeding moved to pigs who could produce more piglets. New president of <a href="https://mercyforanimals.org" target="_blank"><u><em>Mercy for Animals</em></u></a> <a href="https://mercyforanimals.org/meet-leah-garcs-mfas-first-woman-president" target="_blank"><u>Leah Garces</u></a> suggests this could be the cause of the prolapse epidemic: "Over the last few decades, sows to have been bred to have less back-fat—because people don't want to eat as much fat—but we also want them to produce more and more babies. And that's not biologically possible; their bones are weak and they don't have enough fat to support the reproductive process. We've bred them to their limit and the animals are telling us that."</p><p>Sows now produce an average of 23.5 piglets a year in litters of ten. After about four litters, they're done. As Grandin puts it, "They're breeding the sows to produce a lot of babies. Well, there's a point where you've gone too far."</p><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8xODY4MDY3Ny9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0OTA2OTg2MH0.3puetrTWfcjP4pa7t8OLaZA1XLch_jvrINteqCQwMPI/img.jpg?width=980" id="64db4" class="rm-shortcode" data-rm-shortcode-id="358f821eb7ef03b185ddbeda1a73ac0b" data-rm-shortcode-name="rebelmouse-image" />
Exhausted Walkato sow