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.