Retinas made from embryonic stem cells implanted into mice for the first time

U.K. researchers have performed a successful retina transplant in blind mice using light-detecting cells grown from embryonic stem cells.

The team of scientists, from University College London's Institute of Ophthalmology and Moorfields Eye Hospital in London, believe the transplant technique could be refined with human cells to eventually be used in clinical trials as a treatment for degenerative eye diseases.

Using a new process developed in Japan that involves 3D culture and differentiation of mouse embryonic stem cells, researchers grew retinal precursor cells that closely resembled ones that develop normally. They then extracted the light-sensitive photoreceptor cells--those that line the back of the eyes--and transplanted them into night-blind mice. Researchers observed that the cells seemed to develop normally, integrating into the existing retina and forming the nerve connections needed to transmit visual information to the brain.

Photoreceptor cells are key to restoring eyesight because these cells are lost in degenerative eye diseases such as age-related macular degeneration, retinitis pigmentosa and diabetes-related blindness.

Researchers injected about 200,000 artificially grown cells into the retinas of night-blind mice and observed that after three weeks, the artificial cells integrated into the mouse retinas. After 6 weeks, the cells were still present, and researchers observed synapse formation, suggesting that the new cells were able to connect with the existing retinal circuitry. The study, funded by the U.K.'s Medical Research Council, appears in Nature Biotechnology.

Embryonic stem cells' ability to differentiate into virtually any kind of human cell gives them great potential for treating disease, yet embryonic stem cell-based therapies have moved slowly to the clinic. So far, there are no FDA-approved treatments that use such cells, but the U.K. team believes their new technique could provide healthy photoreceptors for retinal cell transplantations to treat blindness in humans.

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- here's the Nature Biotechnology abstract
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