FROM Sweden comes an artificial cornea made from pig collagen molecules which, implanted with an innovative surgery, promises to become a valid alternative to human cornea transplantation. As explained by the researchers of the University of Linköping on the pages of Nature Biotechnologythe small experimentation on 20 people has shown how the new implant is well tolerated and is able to restore (in some cases perfectly) the visual acuity of patients with blindness due to corneal damage.
Corneal damage and transplant
The cornea is that thin transparent membrane, consisting of epithelium and a dense network of collagen fibers, which covers the front of the eye and which acts as the first lens of the visual system: it allows the passage of light and contributes to focus of images on the retina. For this reason, damage to the cornea – whether it is accidental or a consequence of a pathology – compromises vision and in some cases can lead to blindness. As in the case of keratoconus, a disease with hereditary bases that leads the cornea to thin and deform and which in the most serious cases requires a cornea transplant from a deceased donor.
According to estimates, however, human donor corneas are not sufficient to meet the demand: about 12.7 million people worldwide are waiting for a transplant, but the availability is 1 in 70. A chronic shortage, which is it worsens in low- and middle-income countries, to which are added the criticalities of surgery, which in fact is performed in specialized centers.
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From pigskin to cornea
Precisely because of the limitations of human cornea transplantation, research is working to find alternative solutions. Like the one proposed by Mehrdad Rafat and Neil Lagali of the University of Linköping. Scientists, with the support of LinkoCare Life Sciences AB, used porcine collagen, highly purified and processed to be compatible with the human body and to constitute a robust and stable transparent material, to be used as an implant. This artificial cornea – the researchers explained – has the advantage of being made of an easily available material (collagen of porcine origin is also a product of the food industry) and already approved for other medical uses; moreover, the bioengineering has made it stable and resistant, so it can be stored for more than two years, while a human cornea can be implanted within two weeks of collection.
Experimentation
To test whether the new implant could be a safe and effective alternative to corneal transplantation, the Swedish team undertook a small pilot study on 20 patients (Indian and Israeli) with advanced keratoconus. Rafat and Lagali have also developed a new minimally invasive surgical method to implant the artificial cornea in these patients, a technique that does not require the removal of the diseased cornea and the suturing of the new one, but which allows the implant to be inserted into the existing cornea. through a small incision with the laser or even by hand with simple surgical instruments. “A non-invasive method – Lagali specifies – can be used in more hospitals and therefore can help more people”.
The primary purpose of the pilot study was to verify that the implant and the new technique were safe for patients, but the results amazed the researchers themselves. Two years after the operation, the patients’ corneas regained normal thickness and curvature and today all the participants, although 14 were blind at the start of the trial, have regained their sight, three of them even see perfectly.
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The data collected so far, in short, are very promising, but will have to be confirmed by large-scale trials also in Europe and the United States in order to apply for approval to the regulatory authorities as a treatment for keratoconus. In addition, the researchers plan to verify whether the technology can also be used for other corneal diseases and whether, by adapting it to each individual, it can be even more effective.