Approximately 12.7 million people around the world are blind due to corneal stromal disease. Although a transplanted cornea from a human donor is the only way of regaining vision, only 1 in 70 patients receives a cornea transplant. Now, researchers describe a cell-free engineered corneal tissue implant, made of collagen protein from pig’s skin, and a minimally invasive surgical method for its implantation.
A pilot study was conducted in India and Iran, with all 20 patients who received the implants having vision restored. The study is published in Nature Biotechnology, in the article, “Bioengineered corneal tissue for minimally invasive vision restoration in advanced keratoconus in two clinical cohorts.”
“The results show that it is possible to develop a biomaterial that meets all the criteria for being used as human implants, which can be mass-produced and stored up to two years and thereby reach even more people with vision problems,” said Neil Lagali, PhD, professor at the department of biomedical and clinical sciences at Linköping University (LiU) in Sweden. “This gets us around the problem of shortage of donated corneal tissue and access to other treatments for eye diseases.”
In the clinical trial study, twenty people who were either blind, or on the verge of losing sight participated and received the biomaterial implant. The operations proceeded without complications; the tissue healed fast; and an eight-week treatment with immunosuppressive eye drops was enough to prevent rejection of the implant. No complications were noted for the two years that the patients were followed- with conventional cornea transplants, medicine must be taken for several years.
The patients’ cornea’s thickness was improved as well as the curvature restored to normal. The participants’ sight improved as much as it would have after a cornea transplant with donated tissue. Prior to the operation, 14 of the 20 participants were blind; three of the Indian participants who had been blind before the study had perfect (20/20) vision after the operation.
The new cornea consists mainly of collagen molecules derived from pig skin that is a byproduct of the food industry—making it easy to access and economically advantageous. In the process of constructing the implant, the researchers stabilized the loose collagen molecules forming a robust and transparent material that could withstand handling and implantation in the eye. The bioengineered corneas can be stored for up to two years before use, while donated corneas must be used within two weeks.
“A less invasive method could be used in more hospitals, thereby helping more people. With our method, the surgeon doesn’t need to remove the patient’s own tissue. Instead, a small incision is made, through which the implant is inserted into the existing cornea,” said Lagali.
The new, minimally invasive method requires no stitches, and the incision in the cornea can be made with high precision thanks to an advanced laser, but also, when needed, by hand with simple surgical instruments. The method was first tested on pigs and turned out to be simpler and potentially safer than a conventional cornea transplant.
Although a larger clinical study followed by market approval by regulatory authorities is needed before the implant can be used in healthcare, the researchers also want to study whether the technology can be used to treat more eye diseases, and whether the implant can be adapted to the individual for even greater efficacy.
“Safety and effectiveness of the bioengineered implants have been the core of our work,” said Mehrdad Rafat, PhD, adjunct associate professor at LiU’s department of biomedical engineering and founder and CEO of LinkoCare Life Sciences, which manufactures the bioengineered corneas used in the study. “We’ve made significant efforts to ensure that our invention will be widely available and affordable by all and not just by the wealthy. That’s why this technology can be used in all parts of the world.”