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Pig collagen can treat human blindness, study finds

Pigs provide an abundant and inexpensive way to return sight to the sightless.

(CN) — When finding a way to treat blindness, Neil Lagali and Mehrdad Rafat wanted to find an abundant and inexpensive source of collagen, the main component of the human cornea. Pigs proved a reliable source to create cornea implants.

“Our goal was that these implants could one day be mass produced to meet the enormous demand for cornea tissue for transplantation,” wrote Lagali via email. The professor from Linköping University added, “Collagen from pig skin is a byproduct of the food industry and is very abundant and has already been used in FDA-approved products such as dermal fillers. So, it seemed an ideal material for a corneal implant.”

Lagali and co-author Rafat worked on how to produce the collagen molecules from pig skin. Lagali explained that it currently takes three to four weeks to produce enough collagen for 5,000 bioengineered corneal implants. Once the process is complete, the bioengineered corneas are storable for up to two years before use. By contrast, donated corneas have a storage life of two weeks, according to the study published Thursday in Nature Biotechnology.

“This is because the bioengineered corneas do not contain any cells, whereas the donated corneas contain human cells, which die after too long in storage,” explained Lagali.

The endothelial cells, or specialized cells on the back of the cornea, maintain the water balance in the cornea. Once removed from the eye, most of those cells die, then the cornea swells and loses transparency.

Per Lagali, he and Rafat created the corneas with the idea of allowing the patient to keep their own endothelial cells. After all, in the specific disease they were treating, endothelial cells function normally despite the patient losing their sight.

Keratoconus, says the study, is a disease that causes the cornea becomes so thin that it can lead to blindness. In its advanced stage, the patient’s cornea is surgically removed and replaced by a donated cornea sewn into place using surgical sutures.

For the pilot clinical study's 20 keratoconus patients, originally from Iran and India, this invasive surgery isn't always accessible.

“Because there are millions of people with advanced keratoconus who are severely visually impaired or blind, and because of the lack of donor corneas, they cannot get a transplant,” wrote Lagali. “It is also a question of equity, because the majority of people needing a transplant due to advanced keratoconus live in countries where the ability to receive a corneal transplant is severely limited.”

Many people suffer from corneal blindness and low vision in Iran and India, and the 20 people the researchers treated were either blind or on the verge of blindness due to their advanced keratoconus.

The operations were free from complications. According to the study, the patients received the biomaterial implant, their tissue healed fast. Additionally, they only needed an eight-week treatment with immunosuppressive eye drops to prevent implant rejection.

“By contrast,” wrote Lagali, “with standard corneal transplantation using donor tissue, patients receive immune suppression for at least one year, and in many cases even longer.”

As for the eyes, says the study, the cornea’s thickness and curvature restored to normal. After two years, the researchers reported no noted complications. Furthermore, none of the participants were blind, including three Indian participants who gained perfect (20/20) vision.

Thanks to this success, Lagali hopes to obtain funding for larger-scale clinical trials to demonstrate this method can improve a patient’s vision with minimal risk.

“Once we can show that,” wrote Lagali, “we will be able to obtain approvals to market the bioengineered cornea as a product.”

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