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The Eyes Have It: Lab-Made Corneas Restore Vision

August 26th, 2010 08:57 admin Leave a comment Go to comments

biosyntheticSix patients’ eyes have connected with “biosynthetic” replacement corneas, growing nerves and cells into the fakes as if they were real human tissue. With more trials and improvements in implant technique, researchers say the biosynthetic corneas might replace the expensive, rejection-prone, and scarce cadaver corneas that are currently used in transplants. This is good news for people who have lost vision due to inflamed or scarred corneas, and who are hoping to bring the world back into focus.

The findings appeared yesterday in Science Translational Medicine. The corneas allowed six out of a total of ten trial patients with advanced keratoconus, a condition which causes corneal scarring, to see just as well as if they had a traditional cadaver cornea replacement. Natural corneas, which refract light coming into the eye and help it to focus, consist of parallel strands of collagen; the biosynthetic corneas used collagen made in a lab by the biotech company Fibrogen.

“This study … is the first to show that an artificially fabricated cornea can integrate with the human eye and stimulate regeneration,” said May Griffith of the Ottawa Hospital Research Institute, who led the study. “With further research, this approach could help restore sight to millions of people who are waiting for a donated human cornea for transplantation.” [Reuters]

artificial-corneaThe biosynthetic cornea, which mimicked typical tissue’s appearance,  integrated with natural cells and nerves to allow tear production and touch sensitivity. As shown in this (somewhat graphic) New Scientist video, doctors first sutured the corneas in place. After two years, the neighboring cells’ natural growth anchored the biosynthetics down.

[The collagen is] moulded to the shape and size of a natural human cornea. “It looks like a contact lens,” says Griffith. The difference is that this “biosynthetic” cornea encourages the person’s own cells to grow into its matrix, since it is made out of a similar substance to a natural one. [New Scientist]

Although the lenses helped six of the patients see normally, the sutures’ scarring left four with “haze”–a problem that the researchers hope to overcome in stage 2 and 3 clinical trials. They also hope to extend testing of the biosynthetic corneas to people suffering from other corneal conditions.

Cadaver transplants can cost $2,500 each before surgery and are scarce in countries other than the United States. Testing for viruses and other contaminants adds to that cost, ScienceNOW reports, so mass produced biosynthetic corneas that would require much less testing might provide a cheaper and more plentiful alternative for restoring vision to people worldwide.

The new results are “very impressive,” said Shukti Chakravarti, a professor at Johns Hopkins Medical Institute who was not involved in the study. “There is always a dearth of donor tissue, and this would help bypass that.” [Discovery News]

Images: Ottawa Hospital Research Institute, May Griffith et al. / Science Translational Medicine

Even better, by integrating the cornea recipients own cells into the synthetic cornea, the patients should fight off infections more easily, and be more comfortable. “Once those cells grow back they can help contribute to better protection of the cornea,” said Chakravarti.

Source: The Eyes Have It: Lab-Made Corneas Restore Vision

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