Monday, 22 July 2013

Embryonic stem cells restore sight to blind mice

In a new study that was published in Nature Biotechnology, a research team from the University College London's Institute of Ophthalmology and Moorfield's Eye Hospital has successfully restored vision in mice with impaired photoreceptors using embryonic mouse stem cells. There are two types of photoreceptors, which are essentially neuron cells, The two classic photoreceptor cells are rods and cones, the light-sensitive retinal rods and the cones that enable us to see.

The research team, led by Dr. Robin Ali,  was able to integrate into the retina of mice artificial photoreceptor cells that were grown in a laboratory from embryonic stem cells — a breakthrough that built on an earlier study in which the team showed that immature rods obtained from young mice can be implanted into adult mice to restore their sight.


An artificial growth medium eliminates the need for a donor, thus providing the framework for a viable treatment method for humans suffering from similar impairments. Today, the loss of photoreceptors is one of the leading causes of blindness in a wide variety of conditions, including age-related macular degeneration, blindness due to diabetes, and retinitis pigmentosa.

Although the researchers were successful in establishing nerve connections between the artificial photoreceptors and the subject's brain, they say it will take at least five years before any human trials commence.

"Now that we have proved the proof-of-concept, the road is clear to the first set of clinical trials just to see whether it'll work. It certainly isn't a case of rolling out treatments in five years' time and providing therapies. It's taken us 10 years to get here and it'll take us five years to get started in people." said Ali to the guardian.

During the past 10 years, Ali and his colleagues have slowly but steadily progressed to the transplant success rate displayed in the study. Since 2006, it has risen from 0.5 percent to about 20 percent; for every 200,000 transplanted cells, 40,000 are now integrated into the subject's retina.

"If we can transplant 20,000 cones in macular degeneration, I think there's potential for tremendous clinical benefit because humans don't need very many functioning cones for a really useful function. The foveola, in the centre of the fovea  which is responsible for really high visual acuity — things like reading — has only 20,000 cones. That gives you an idea just how few cells you might need." said Ali.

While some express concern that the mouse model is not an adequate approximation of the human retina's complexity, few are denying the significance of the new method.

"Restoring the sight for the 'three blind mice' may be far easier than for the 'farmer's wife,'" said Professor Chris Mason, a stem cell biologist at University College London.

"Before human clinical trials can commence, the mouse model will require significant optimization, for example increasing the efficiency of new photoreceptors to connect with the damaged retina. However, there is no doubt that this breakthrough, either directly as the basis of a future cell therapy, or indirectly by expanding our knowledge, will significantly contribute to the fight against blindness," he said.

Reference
1) Anai Gonzalez-Cordero, Emma L West, Rachael A Pearson, Yanai Duran, Livia S Carvalho, Colin J Chu, Arifa Naeem, Samuel J I Blackford, Anastasios Georgiadis, Jorn Lakowski, Mike Hubank, Alexander J Smith, James W B Bainbridge, Jane C Sowden & R (2013). Photoreceptor precursors derived from three-dimensional embryonic stem cell cultures integrate and mature within adult degenerate retina Nature DOI: 10.1038/nbt.2643

2 comments:

  1. This is a huge stem in the world of regenerative medicine!

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  2. My name is Sharon McKinney. Your research is promising. I had a stroke to my right eye in 2010. Total lost. If ever you need to use a human subject, I would be pleased to be that person.Please keep up the good work. God bless you. sharonmc211@msn.com

    ReplyDelete

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