Scientists in the US and China have provided tantalising evidence of the potential for an eye drop treatment for cataracts, which could advance to clinical trials in as little as a year.
The research, published in the journal Nature, shows that treating cataractous lenses with lanosterol, a molecular building block of steroids, was found to reduce the cloudy protein build up in the tissue. The findings identify the molecule as a key component in cataract formation and highlight its potential as a non-surgical treatment.
Led by researchers at the University of California, San Diego (UCSD), the team sequenced the DNA of a number of children with congenital cataracts, finding that mutations in genes related to the production of lanosterol.
Additional experiments with modified cells unable to produce the molecule resulted in misfolded proteins and aggregates, like those in cataracts.
Using cataractous lenses taken from rabbits, the team found that incubating the lens with lanosterol solution for a number of days reduced the opacity of the tissue. Lanosterol eye drops were also found to increase clarity of the lens in dogs with age-related cataracts.
Cataracts are estimated to be responsible for more than half of all blindness in the world, affecting 20 million people, with surgical removal of the lens the only treatment. While a class of crystallin proteins are known to play a role in cataracts through the formation of clumps, or aggregates, the exact mechanism remains unclear.
The production of lanosterol is itself a key step in the synthesis of cholesterol, steroid hormones and vitamin D. The researchers suggest that the molecule may penetrate the protein clumps, enabling them to become water soluble.
Professor Kang Zhang, from UCSD, told Nature: “Our study is the first one to show that lanosterol and [its] related compounds may be a new class of drugs that is evolving; dissolving protein aggregates and then treating misfolded protein complexes, restoring lens clarity and preventing cataract formation.”
He added: “Since lanosterol is a molecule produced by...our own body, the toxicity issue of a drug will be minimal, if any. So I anticipate that we will be going to clinical trials for treating cataract within a year.”
Professor Zhang confirmed that there are also experiments to see if the molecule could be used to treat other conditions involving protein aggregates, such as Alzheimer’s and Parkinson’s.
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