Swine Of The Times: Pig-to-Human Organ Transplants On Track For 2021

Every day in the US, seventeen people die because they couldn’t get a organ transplant in time. An American biotech company called United Therapeutics is looking to pick up the lifesaving slack by producing a line of genetically-modified pigs for the purpose of harvesting their organs, among other therapeutic uses. United Therapeutics’ pig-farming subsidiary Revivicor is a spin-off of PPL Therapeutics, the company that gave us Dolly the cloned sheep back in 1996. They intend to start transplanting pig organs into humans as early as this year.

Baby Fae after transplant surgery. Image by Duane Miller-AP via Time Magazine

Although it sounds like science fiction, the idea of transplanting animal cells, organs, and tissue into humans has been around for over a hundred years. The main problem with xenotransplantation is that it usually triggers severe immune system reactions in the recipient’s body. In one of the more noteworthy cases, a baby girl received a baboon heart in 1984, but died a few weeks later because her body rejected the organ.

The leading cause of xenotransplant rejection is a sugar called alpha-gal. This sugar appears on the cell surfaces of all non-primate mammals. Alpha-gal is problematic for other reasons, too: a condition called alpha-gal syndrome usually begins when a Lone Star tick bites a person and transmits alpha-gal cells from the blood of animals they have bitten. From that point on, the person will experience an allergic reaction when eating red meat such as beef, pork, and lamb.

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Spider Silk, Spider Silk, Made Using A Strain Of Yeast

Companies spend thousands developing a project for the market, hoping their investment will return big. Investing like this happens every day and won’t shock anyone. What may surprise you is someone who spends more than a decade and thousands of their own dollars to make an open-source version of a highly-marketable product. In this case, we’re talking about genetically modified yeast that produces spider silk. If that sounds like a lead-in to some Spiderman jokes and sci-fi references, you are correct on both accounts. [Justin Atkin] had some geneticist work under his belt when he started, so he planned to follow familiar procedures like extracting black widow DNA, isolating and copying the silk genes, and pasting them into a yeast strain. Easy peasy, right? Naturally, good science doesn’t happen overnight.

There are a few contenders for the strongest spider silk among which the golden silk orb-weaver gets the most attention, but the black widow’s webbing is nearly as strong, and [Justin] is happy to wear black widow inspired bling, whereas the golden orb-weaver looks like it crawled out of Starship Troopers. His first attempt to extract DNA starts with a vial of preserved nightmare fuel spider specimens because that is a thing you can just go online and buy. Sadly, they were candied in alcohol, and that obliterates DNA, so he moved to dried specimens from breeders, which also failed to produce results, and those were just the landmark hangups.

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