Cornea made of leather
A study jointly conducted by a group from Linkoping University, Sweden, and LinkoCare Life Sciences AB has shown the effectiveness of a bioengineered corneal implant as an alternative to transplantation of donor human corneas.
Affordable
It is estimated that 12.7 million people worldwide are blind due to injuries or diseases of the cornea - the outer transparent shell of the eye. In this case, the only way to restore vision is a corneal transplant from a human donor, but only one out of 70 patients receives it. In addition, most of those who need a corneal transplant live in low- and middle-income countries where access to treatment is limited.
Mehrdad Rafat, the researcher and entrepreneur behind the design and development of implants, and his colleagues have made significant efforts to ensure that the invention is widely available to everyone, regardless of personal income and health development.
The cornea consists mainly of collagen fibers, tightly stacked to each other in even rows. To create an engineered alternative to the human cornea, the researchers used collagen molecules derived from pig skin. Pork skin is a by-product of the food industry, so it is an easily accessible and cost-effective component. In the process of manufacturing the implant, the researchers stabilized free collagen molecules, forming a durable and transparent material capable of withstanding manipulation and implantation into the human eye.
While donor corneas should be used within two weeks, bioengineered corneas can be stored for up to two years before use.
A new surgical method
Researchers have also developed a new minimally invasive method for the treatment of keratoconus, a disease in which the cornea becomes so thin that it loses its transparency, leading to vision loss. Today, the cornea of a patient with keratoconus at a late stage is surgically removed and replaced with a donor cornea, which is fixed with surgical sutures. This operation is invasive and is performed only in large hospitals.
A less invasive method could be used in more hospitals, thereby reaching more people. The new method does not require the removal of the patient's own tissues. Instead, a small incision is made through which the implant is inserted into the existing cornea. Suturing is not required. The incision in the cornea can be performed with high accuracy thanks to a femtosecond laser, as well as, in its absence, manually using conventional surgical instruments. The method was tested on pigs and turned out to be simpler and potentially safer than a conventional corneal transplant.
The new surgical method and pig collagen implants were tested in a pilot clinical trial in Iran and India involving 20 blind and visually impaired volunteers with progressive keratoconus. All operations were performed without complications, the tissues healed quickly, and an eight-week treatment with immunosuppressive eye drops was enough to prevent the rejection of the implant. With a conventional corneal transplant, immunosuppressants must be taken for several years. The patients were followed up for two years, and during this time no complications were noted.
Perfect vision
The main goal of the pilot clinical trial was to find out whether the implant is safe to use. However, the researchers were surprised that after implantation of the bioengineered cornea, the thickness and curvature of the own cornea were restored to normal values. Before the operation, 14 out of 20 participants were blind (visual acuity less than 0.05, or 5% according to WHO criteria). After surgery and after two years, none of them were blind anymore, and three participants who were blind before the study showed perfect vision after surgery (1.0, or 100%).
Before the large-scale use of a bioengineered implant, a larger clinical trial should be conducted with subsequent regulatory approval. The researchers also plan to explore whether this technology can be used to treat other eye diseases and whether the implant can be adapted to a specific patient for even greater effectiveness.
Article by M.Rafat et al. Bioengineered corneal tissue for minimally invasive vision restoration in advanced keratoconus in two clinical cohorts is published in the journal Nature Biotechnology.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru based on the materials of the Linking University: Bioengineered cornea can restore sight to the blind and visually impacted.