New stem cell technique restores sight to blind mice
Oxford University researchers have transplanted developing cells into the eyes of completely blind mice to re-form the entire light-sensitive layer of the retina.
The mice, which once didn't notice the difference between light and dark at all, now prefer to be in the dark, like mice with normal vision.
The research has exciting implications for treating patients with retinitis pigmentosa, in which the light-sensing cells in the retina gradually die.
The researchers worked with mice that are blind due to complete loss of the light-sensing photoreceptor cells in their retinas. However, they say, it took just two weeks for the transplanted precursor cells to re-form a full light-detecting layer on the retina - and allow the mice to see.
A pupil constriction test showed that, of the 12 mice that received the cell transplant, 10 showed improved pupil constriction in response to light. This shows that the retinas of the mice were sensing the light once more, and that this was being transmitted along the optic nerve to the brain.
"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," says Dr Mandeep Singh, an eye surgeon from the National University Hospital of Singapore who is currently undertaking PhD studies in Oxford.
Next, the team hopes to try a similar experiment with induced pluripotent stem cells, or iPS cells. These are stem cells that have been generated from the patient's own cells, such as skin or blood cells, and which can then be directed to form precursors of the retina cells.
"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," says Professor Robert MacLaren of the Nuffield Department of Clinical Neurosciences at the University of Oxford.
"We have shown the transplanted cells survive, they become light-sensitive, and they connect and reform the wiring to the rest of the retina to restore vision."