Light-sensing retina created using stem cells

In a research first, a section of light-sensing tissue, closely resembling the human retina, has been grown in the laboratory from human stem cells.

Dr Maria Canto-Soler, an assistant professor of ophthalmology at John Hopkins University in the USA, and lead author of the study, said: 'We have basically created a miniature human retina in a dish that not only has the architectural organisation of the retina but also has the ability to sense light'.

The retinas were grown using human induced pluripotent stem cells (iPSCs), adult cells that have been genetically reprogrammed to behave similarly to embryonic stem cells.

Using iPSCs, the researchers first generated precursor retinal cells by growing them in a medium containing specific growth factor chemicals. The researchers were surprised to see that the cells assembled into a complex structure, in steps similar to those observed in the eye during fetal  development.

The tissue not only structurally resembled the human retina, but it also contained all major retinal cell types arranged in their proper layers.

Dr Canto-Soler said: 'The stem cells could build up the retinal structure almost autonomously. Somehow the cells knew what to do and we just needed to give them time to do it'.

The scientists were also interested to see whether their model was able to give rise to functional photoreceptors, the light-sensing cells of the retina. Photoreceptor damage is a common cause of blindness.

They found that their artificial retina contained cells that not only resembled photoreceptors structurally, but were also able to respond to light.

Dr Canto-Soler commented that this finding 'advances opportunities for vision-saving research and may ultimately lead to technologies that restore vision in people with retinal diseases'.

She also highlighted, however, that light-sensing only provides a small part of the vision-making process. 'Is our lab retina capable of producing a visual signal that the brain can interpret into an image? Probably not, but this is a good start'.

The lab retina was tested at a stage equivalent to 28 days of fetal development and the scientists will now try to develop their model further.

Dr David Gamm of the University of Wisconsin, a co-author of the study, told The Scientist: 'Knowing the mechanism in greater detail will allow us to improve the retinal differentiation process, making it more safe, reproducible, and user-friendly for both disease modelling and drug testing and for clinical transplantation into patients'.

Talking to The Scientist, Dr Canto-Soler, however, said: 'there is still a long way to go before we can directly apply this to patients'.

The research was published in Nature Communications.