Clinical trial restored sight in 20 people with corneas made from an unlikely source: ScienceAlert

Implants made from pig skin have restored vision to 20 people with diseased corneas in an exciting clinical trial study. Many of the patients were blind before receiving the help of this biotech tissue.

Incredibly, after two years, all 14 of those blind had regained their sight and three of them, and three of them now have perfect 20/20 vision.

“This will avoid the problem of [a] shortage of donated corneal tissue and access to other treatments for eye diseases,” said ophthalmology researcher Neil Lagali of Linköping University.

While about 12.7 million people suffer from vision loss due to problems with their cornea, only 1 in 70 manage to have a corneal transplant – the only way to restore their vision.

Because the resources to perform these transplants are costly and donated corneas are scarce, most people in the world do not have access to effective treatments.

“We have made significant efforts to ensure that our invention will be available and affordable to everyone and not just to the wealthy. Therefore, this technology can be used in all parts of the world,” said Mehrdad Rafat, biomedical engineer from Linköping University .

To accomplish this, Rafat and colleagues developed a new technique that does not require sutures, allowing doctors to perform the implant procedure using less specialized conditions and equipment.

“A less invasive method could be used in more hospitals, helping more people. With our method, the surgeon does not have to remove the patient’s own tissue. Instead, a small incision is made, through which the implant is placed in the existing cornea,” explains Lagali.

In addition, the material used to make the implant is a by-product of the food industry and specially developed packaging and sterilization processes allow the final product to be stored for up to two years. In contrast, donated human corneas must be used within two weeks.

Our cornea – the clear screen over the front part of our eye that shields our iris and pupil – is largely made up of different types of collagen. This structure can gradually thin over time, causing it to bulge outward and distort our vision in a condition called keratoconus.

While the exact cause of this thinning is not known, genetics, vigorous rubbing the eyes, and conditions such as hay fever, asthma, Down syndrome, and Ehlers-Danlos syndrome can increase the chances of developing keratoconus.

So the researchers purified collagen from pig skin to create a new corneal layer. They used chemical and photochemical methods to strengthen this mostly soft material, making it more stable, resulting in a hydrogel they call a bioengineered pig construct, double cross-linked (BPCDX).

Changes in corneal thickness with arrows contouring the implant after surgery.
Changes in corneal thickness with arrows indicating implant circumference after surgery (bottom). (Rafat et al, Nature Biotechnology2022)

By refining their techniques in animal models, researchers then developed a simple method to introduce BPCDX into the recipient’s cornea, eliminating the need to remove the existing tissue.

Here, the implant smooths out corneal kinking and provides lost thickness, restoring the eye’s ability to focus.

The minimally invasive surgery leaves the corneal nerves and cell layers intact, allowing the wound to heal quickly.

After implantation through a 2 millimeter incision, the BPCDX successfully remained transparent. There was no scarring or side effect, and no intensive therapy or further surgery was required; just an eight week treatment with immunosuppressive eye drops and a bandage.

The biotech cornea checked all the lockers.

After two years, participants from Iran and India experienced an average increase of more than 200 micrometers in the thickness of their cornea and a decrease in its curvature, improving their vision at least to the extent of traditional corneal transplants.

Previous attempts to place biomaterial implants in the eye eventually thinned out, but the reinforced collagen from pig cells held strong and kept the implant stable even after eight years, the team reported based on their previous studies and unpublished data.

“No previous study, to our knowledge, has achieved complete corneal transparency in vivo with sufficient corneal thickening and flattening, or with significant improvement in visual acuity as reported here,” the researchers wrote in their paper.

A larger clinical trial is now planned, but if the pilot is any indication, the researchers are hopeful of additional promising results that will help the new procedure meet regulatory approvals.

“The results show that it is possible to develop a biomaterial that meets all the criteria for use as human implants, which can be mass-produced and stored for up to two years, thus helping even more people with vision problems.” reach,” concludes Lagali.

This research was published in Nature Biotechnology.

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