Tuesday, 8 January 2013

Blind mice regain vision after stem cell transplant

A new study on retinitis pigmentosa was published yesterday by researchers at Oxford University. The study is very promising and reveals the great potential in using stem cells for treating the condition. Another study on the condition, involving gene therapy and iPSCs, was also published a few days ago, you can check it here.

During the study the researchers, led by Professor Robert MacLaren,  experimented on mice that had lost their vision due to complete loss of photoreceptors. Photoreceptors are specialised neurons, capable of visual phototransduction, a process by which light is converted into electrical signals.

Normal vision on the left , retinitis pigmentosa vision on the right

The researchers began the study by transplanting precursors cells into the eyes of twelve mice. These precursor cells were derived from stem cells and had already started the path of differentiating into retinal cells. Two weeks later, the mice had their pupilary light reflex tested and 10 of them showed greatly improved pupil constriction. What this means, is that the transplanted stem cells had developed into photoreceptors and as a result the mice partially regained their vision. In another the same mice were running to the dark and away from the light, classic behaviour of nocturnal mice.

Image showing the pupilary light reflex

Singh says:

"We found that if enough cells are transplanted together, they not only become light sensing but they also regenerate the connections required for meaningful vision."

And MacLaren adds:

"Stem cells have been trialled in patients to replace the pigmented lining of the retina, but this new research shows that the light-sensing layer might also be replaced in a similar way. The light-sensing cells have a highly complex structure and we observed that they can resume function as a layer and restore connections after transplantation into the completely blind retina."

According to the researchers their next step is to try induced pluripotent stem cells and study their efficacy in treating the condition.

-Robert MacLaren is a Professor in the Nuffield Department of Clinical Neurosciences at the University of Oxford

-Dr Mandeep Singh is an eye surgeon at the National University Hospital of Singapore

Singh MS, Charbel Issa P, Butler R, Martin C, Lipinski DM, Sekaran S, Barnard AR, & Maclaren RE (2013). Reversal of end-stage retinal degeneration and restoration of visual function by photoreceptor transplantation. Proceedings of the National Academy of Sciences of the United States of America, 110 (3), 1101-6 PMID: 23288902

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