Smithfield Foods sells bacon, ham, hot dogs, pork chops, and sausages (breakfast, smoked, and dry). It also supplies pharmaceutical companies. Heparin, a molecule extracted from pig guts, is the crucial ingredient in blood-thinning drugs.

It makes sense when you think about it: Meat and organs tend to come in a single package (i.e. a pig), so of course the world’s largest pork processor is also a major U.S. heparin supplier. With that in mind, it also makes sense that Smithfield has a growing interest in pig-to-human organ transplants.

Earlier this month, the company announced a new bioscience unit that will work with medical companies interested in pig parts—perhaps even organs for transplant one day. “We want to signal to the medical-device and science communities that this is an area we’re focused on—that we’re not strictly packers,” Courtney Stanton, Smithfield Bioscience’s vice president, said in an interview with Reuters.

Pig-to-human organ transplants are still many years and a few technical breakthroughs away. But pork byproducts—to use the industry term for the non-meat bits—already turn up in all sorts of drugs and medical devices for humans. It’s not just heparin. Skin, hormonal glands, and heart valves are some of the common pork byproducts in the biomedical industry. Special breeds of pigs are also used to test medical devices. Pigs are similar in size and genetics to humans, and factory farming has made them very widely available.

In an industry that operates on a philosophy of “everything but the oink,” very little of a pig goes to waste. Organs not eaten by humans go into pet food. Bones and other parts usually go to rendering plants, where they’re broken down into ingredients for anything from linoleum to industrial lubricants. Biomedical products present a more lucrative and supposedly high-minded opportunity though.

“Sausage is a wonderful thing,” says Johnsonville Sausage’s vice president, Kevin Ladwig. “But improving human health and quality is a very inspirational goal that we have.” Johnsonville set up a division five years ago focused on finding biomedical uses for pig parts. The company has long sold heart valves, but it’s looking to expand its catalog. Smithfield is now doing the same.

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The idea of using pigs in human medicine has been around for a long time. New Food Economy points out that the first pig-to-human corneal transplant happened in 1838. But insulin was the first product to demonstrate that pork byproducts could save human lives on a massive scale.

(Eli Lilly and Company Archives)

Childhood diabetes used to be a death sentence. The only treatment, if you could call it one, was a starvation diet. Then in 1923, Eli Lilly began selling insulin extracted from pig pancreases, the organ that normally makes the hormone. A diabetic child, starving and frail, could be treated with insulin and miraculously restored to plumpness. It was the wonder drug of its day.

The transformation of slaughterhouse waste into life-saving medication happened at Eli Lilly’s factory in Indianapolis. Trains pulled up bearing piles of pancreases. Workers ground them up. The resulting slurry passed through a series of vats and filters to became increasingly pure insulin, which ultimately came in a sterile, glass bottle.

A photograph shows the 10,000-pound pile of pancreases need to make one pound of concentrated insulin crystals.

(Eli Lilly and Company Archives)

Pancreases aren’t the only organ with useful molecules inside. A 1990 report from Purdue University’s Cooperative Extension Service runs through a long list of organs that can be used in pharmaceutical products: adrenal glands (steroids), pineal gland (melatonin), thyroids (thyroxine for metabolic disorders), parathyroids (hormones for blood calcium content), blood (thrombin for blood clotting), pituitary gland (several hormones including for growth), and on and on. Scientists now have found cheaper ways to make many of these pig-derived drugs synthetically, including insulin. Heparin is a major exception.

Other pig products still used in medicine today tend to be structurally complex or molecularly diverse—difficult to make in a lab compared to a single substance like insulin. Heart valves, for example, often come from pigs. They are the right shape and size for humans. After heart valves go from slaughterhouse to medical-device factory, a detergent solution is used to remove any pig cells that a patient’s immune system could recognize as foreign. (Since heart valves open and close passively, you don’t need any living cells for them to work.) Heart surgeons first implanted the porcine heart valve in 1960s, and thousands of patients now have them.

Another very common product is derived from pig skin. Here, the cells of the dermis are washed away to reveal the protein scaffold on which cells usually grow. This is the extracellular matrix, and it contains all sorts of proteins and molecule that promote healing. Extracellular matrix, once processed, can come as powder, sheets, or mesh. Stephen Badylak, a pioneer in using porcine tissues in regenerative medicine now at the University of Pittsburgh, ticked off a few of the uses for me: “You’ve got hernia repair, topical wound care for diabetics, muscular tendon defects, rotator cuffs, Achilles tendon repair.” He estimates 8 to 10 million patients have been treated with these decellularized porcine materials, which are sometimes also made from other tissues like liver.

The ambitious next step is pig-to-human organ transplants. Miromatrix Medical, which currently offers decellularized matrix for wounds, is also working on growing whole organs. It starts with a similar process. The company takes a pig liver and removes all the cells, leaving only a ghostly, liver-shaped protein scaffold on which it then tries to grow human liver cells.

Keeping the structure of the protein scaffold is important, which is why the company has special partnerships with local farms and slaughterhouses. “We make sure it doesn’t have any nicks and cuts it, which takes a little bit of training,” says CEO Jeff Ross. He says the company is aiming to do the first human implant sometime in 2020 or 2021.

At Harvard, the geneticist George Church and his colleagues have a possibly even more ambitious strategy for pig-to-human transplants: genetically modifying pigs, so their organs can be directly transplanted into humans with no immune reaction. This would probably sever the link between meat and organ production though, as people have shown very little appetite for genetically modified pork.

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Given that pig products go from slaughterhouse (messy, chaotic) to lab (clean, sterile) to the human body, you might wonder about quality control. The FDA largely doesn’t have specific rules that cover pig tissue sourcing in medical devices.

That said, pig heart valves and skin have been used largely without incident in the U.S. Heparin is another story. In 2008, impurities from heparin produced in China killed more than 80 people in the U.S. Newspapers ran grisly photos of Chinese factories where workers handled pig intestines. (Smithfield Foods was acquired by the Chinese company Shuanghui in 2013, and a major sticking point then was concerns about the heparin supply.  The FDA has tightened regulations on heparin as a drug since the 2008 scandal.)

Tissue Source, a company based in West Lafayette, Indiana, has staked its reputation on careful sourcing of pig parts for biomedical use. It works with a farm that grows pigs for breeding stock rather than solely for food, so the farm already takes certain biohazard precautions. “You can’t just drive up to the facility and go in,” says Tissue Source’s CEO, Sherry Ziobro. “There’s a shower in and shower out procedure.” Tissue Source also follows European standards, which tend to be stricter. All of their products can be traced back the exact pig they came from.

Ladwig, the Johnsonville Sausage executive, says he expects traceability and quality control in the industry to go up—not necessarily because of the FDA but because of consumers. The pork industry is already under pressure to abandon practices like widespread antibiotic use and gestation crates. People are demanding more transparency and accountability in their food. You’d expect the same for their drugs and medical devices. And, when it comes to this, you’d expect the same for a heart.