July 22, 2013
A new study published in the journal Nature Biotechnology represents a major step forward in curing certain types of blindness.
Described to the BBC News as a significant breakthrough, the UK-based study outlined a groundbreaking technique developed by doctors at Moorfields Eye Hospital and University College London that uses stem cell therapy to replace photoreceptors that may have died as a result of Stargardts disease or age-related macular degeneration.
While previous efforts have successfully focused on keeping the photoreceptors support cells alive, the new treatment aims to replace the retinas key cells directly. These cells sense light and are connected to other cells that relay the visual information to the brain.
The new technique expands on work done by Japanese researchers who used mice stem cells to fashion new retinas. The London team created photoreceptor cells and placed them in the eyes of blind mice.
After being injected, the new cells were able to connect with the mices existing framework albeit at a relatively low level of effectiveness. Approximately 1,000 of the 200,000 transplanted cells were able to connect with the rest of the eye.
This is a real proof of concept that photoreceptors can be transplanted from an embryonic stem cells source and it give us a route map to now do this in humans, said lead researcher Robin Ali, a professor of Human Molecular Genetics at the University College of London. Thats why were so excited, five years is now a realistic aim for starting a clinical trial.
The eye is one of the most promising candidates for stem cell therapy because there is only one type of intermediary cell between photoreceptors and the brain, unlike other organs which require far more connections between newly generated cells. A relatively small number tens of thousands of stem cells could improve vision, a number that would not make much of a difference in the liver or brain.
The eyes relatively weak local immune system also makes it an ideal candidate for stem cell therapy. A weak immune system means a lower chance of transplanted cells being rejected.
While experts described the study as a huge leap forward, some expressed concerns about the stem cells relatively low connection rate.
More here:
Using Stem Cells To Treat Blindness