A corneal implant created from pig skin has successfully restored sight in 20 blind or visually impaired people as part of a promising trial.
The implant is made from the animal’s collagen protein and resembles the human cornea, the transparent part of the eye that covers the iris and pupil.
Scientists from Linkoping University and LinkoCare Life Sciences AB have developed the implant as an alternative to donated human corneas, as well as a less invasive surgery for implantation.
The results of the pilot study are expected to bring hope to those living with corneal blindness and low vision.
Professor Neil Lagali, who led the project, said: “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 and , therefore reaching even more people with vision problems.
“This brings us to the problem of the shortage of donated corneal tissue and access to other treatments for eye diseases.”
The corneal implant is made of collagen protein from pigs and resembles the human cornea, the transparent part of the eye that covers the iris and pupil.
Scientists have developed the implant as an alternative to donated human corneas, as well as a less invasive surgery for its implementation that can be done by laser.
Pig skin is economically viable and readily available worldwide as it is the byproduct of the food industry (stock image)
WHAT ARE THE BENEFITS OF THE NEW CORNEAL IMPLANT?
- Made with an inexpensive and easily accessible material – Corneal transplants are usually done with donated human corneas, which are not readily available.
- Less invasive implantation surgery – Implantation requires only a small incision in the eye to allow placement of the cornea, which can be done with a laser. Surgical removal of the patient’s tissue is not necessary.
- Post-operative eye drops are only needed for eight weeks – Current corneal transplants require years of follow-up medication.
An estimated 12.7 million people worldwide are blind due to damaged or diseased corneas, which restrict the amount of light that enters the eye.
However, only one in 70 patients receives a cornea transplant, and those who need it tend to live in low- and middle-income countries where access to treatments is very limited.
Mehrdad Rafat, the researcher and entrepreneur behind the implants, said: “We have made significant efforts to ensure that our invention is widely available and affordable for everyone and not just the rich.
“That’s why this technology can be used in every part of the world.”
In a study, published yesterday in Nature Biotechnology, researchers describe how they created the cornea using collagen molecules from pig skin.
The material is economically viable and easily accessible worldwide, as it is a by-product of the food industry.
The researchers first stabilized the loose collagen molecules to create a robust material that could withstand implementation in the eye.
Although donated corneas must be used within two weeks, bioengineered corneas can be stored for up to two years before use.
The paper also describes how the new implant can make surgery to implement the new cornea less invasive.
Left: Photo of the corneal implant made of pig skin collagen (BPCDX), indicating its transparency and refractive nature. Right: Light transmission through 550 µm-thick samples of BPCDX, a unique cross-linked version of the implant (BPC), and the human cornea
The researchers first stabilized the loose collagen molecules to create a robust material that could withstand implementation in the eye. Pictured: Electron microscope images of the surface and cross-section of porcine (porcine) cornea compared to corneal implant (BPCDX).
The standard procedure is to surgically remove the patient’s damaged cornea before the new one is sewn into place.
However, the installation of the bioengineered cornea does not require the removal of the patient’s tissue and no stitches are required.
Professor Lagali explained: “Instead, a small incision is made, through which the implant is inserted into the existing cornea.”
This can be done with an advanced laser or by hand with simple surgical instruments, as has been tried in the past in pigs.
“A less invasive method could be used in more hospitals, thus helping more people,” the professor added.
The patients were followed for two years after the operations and, according to the study, had no complications. Pictured: Photographs of two subjects’ eyes with the corneal implant four months after the operation, showing that it retained transparency
A: Photographs of a patient’s cornea before surgery (left) and one day after surgery (right) with arrows indicating a change in thickness and curvature in the central cornea. B: Ocular scans showing sustained thickening and corneal curvature after implantation of a 280-µm-thick corneal implant. The front and back surfaces of the implant are indicated by white arrows
Twenty people with advanced keratoconus participated in the pioneering trial of the biomaterial implant.
Keratoconus is a condition that occurs when the cornea thins and gradually bulges outwards in a cone shape, and can lead to blindness.
The surgeries were performed in Iran and India, countries where there is a significant lack of treatment options for those with corneal blindness and low vision.
The patients were followed for two years after the operations and, according to the study, had no complications.
His eye tissue healed quickly and his cornea healed thickness and curvature were restored to normal.
With conventional corneal transplants, the drug must be taken for several years after surgery, but just an eight-week course of immunosuppressive eye drops was enough to prevent rejection of the new implant.
Before the procedure, 14 of the 20 participants were blind, but after two years all had regained their sight.
Three of the Indian patients who had been blind before the study had perfect, 20/20 vision after the operation.
Further clinical study followed by regulatory approval is still required before the implant can be used in healthcare.
The researchers also want to study whether it can be used to treat other eye diseases and whether it can be tailored to the individual patient for even better results.
Surgeons successfully transplant two PIG KIDNEYS into brain-dead Alabama man
Surgeons at the University of Alabama at Birmingham successfully transplanted two pig kidneys into a brain-dead human in January.
Jim Parsons, 57, of Huntsville, Alabama, was brain dead and thus officially pronounced dead in September after suffering a traumatic head injury during a dirt bike race.
With the blessing of his family, researchers performed the pioneering transplant just four days later, where his kidneys were removed while his blood was still circulating.
He was then given two organs taken from a genetically modified pig, which filtered blood, produced urine and were not immediately rejected by his body.
Both organs remained viable for three days after transplantation, demonstrating how xenotransplantation, the transplantation of living cells, tissues or organs from one species to another, could address the organ shortage crisis in all the world.
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