Stem cells regrow the lens and repair the front of the eye

Big news today for research to repair the eye with stem cells. A team of scientists in the USA has demonstrated for the first time that lens cells themselves can re-grow a working lens in babies born with cataract in both eyes by changing the current surgical technique. And another team in Japan has shown that tissue grown from stem cells can mimic whole eye development and could make it possible to transplant the front of the eye to restore vision. Both studies were published in the journal Nature.

Cataract is the number one cause of blindness worldwide. If affects the lens that sits just behind the coloured part of the eye. We use the lens to help focus light for clear vision. It needs to be clear to let light pass through, but in cataract the lens becomes cloudy. Cataracts are most common in older people but can happen at any age, and in rare cases, some babies are born with cataracts or develop them at an early age.

Millions have artificial lens implants

Until now the only treatment for cataract has been to replace the cloudy tissue with an artificial implant into the eye. It’s the most common surgical procedure done by the NHS and each year around 20 million people worldwide have the operation.

Surgery on babies with congenital cataract can mean long and difficult recovery times. It can also lead to complications such as glaucoma and all children who have the operation need corrective glasses afterwards.

Less invasive surgery

But now a team of researchers at the University of California San Diego has developed a new, less invasive way to restore sight, by keeping the front layer of the natural lens (the lens epithelium) and letting it regrow. The lens epithelium contains stem cells that are there to help protect the lens from injury. They can grow into cells that can repair the lens.

In this study, the team removed cloudy lens tissue through a small cut, keeping the outer-layer intact and then let the lens epithelial stem cells regrow. They first tried the technique in rabbits and macaque monkeys, and, when it was successful, in 12 children in China under the age of 2, with inherited cataracts. The authors report that the children recovered from the surgery within a month and had better outcomes than children who had standard treatment.

Wake up and smell the coffee

Fight for Sight researcher Professor Roy Quinlan is working on stem cell regeneration to repair the lens in the School of Biological and Biomedical Science at Durham University. He said: “The innate regenerative potential of the lens has been known for nearly two centuries since the observations of Cocteau and Leroy-d’Etoille in 1825, but Liu/Zhang groups are the first to bring this observation to clinical trial. Hopefully, others will ‘wake up and smell the coffee’ and map the boundaries of this approach for the treatment of cataract in humans.

“We don't know whether it will work in adults, we don't know how visual perception might be affected in the treated infants and we don't know whether this can be adapted for congenital cataract. The same group published last year that the natural product, lanosterol can reverse age-related cataract and so surgical intervention might not always be needed. Nevertheless, it would seem that the group have both ends of the age spectrum covered and it is most encouraging to see new therapies and treatment for cataract”.

Mimicking eye development

The second team of researchers have been working at Osaka University in Japan. They have used a type of stem cell that comes from skin to grow several important types of eye tissue in a way that mimics eye development. It is tempting to think of a parts list for the eye, but there is much more to be understand about the underlying biology before this becomes a reality. Nevertheless, the team has already demonstrated the potential by transplanting corneal tissue onto the front of the eye in blind rabbits, repairing the eye and restoring vision and this is a very important first step.

Dr Dolores M Conroy is Director of Research at Fight for Sight. She said “These are two very important studies that show the great potential of stem cells to repair the eye and give sight back in certain forms of blindness. There are many questions that still need to be address, for example, how tissue grown outside the body for the back of the eye could be integrated into the visual system as a whole. This is an area of intense research activity around the world and we look forward to seeing the next steps develop.”

Fight for Sight research

Take a look at Fight for Sight’s research into cataract and stem cells, including a new NHS test to help children with inherited cataract get the right care.