Cultured in a dish, stem cells spontaneously assembled themselves into a complex structure resembling an eye – a retina, to be exact.
The discovery may help the development of eye disease treatments, such as stem cell-derived transplants for repair of the retina, which is lined with the light-sensing cells we need for vision.
It could one day provide an endless supply of cells for ‘the next generation of generative medicine in retinal degeneration therapeutics,’ according to the authors.
The optic cup is brandy-snifter-shaped organ that has two distinct cell layers. The outer layer – that nearest to the brain – is made up of pigmented retinal cells that provide nutrients and support the retina. The inner layer is the retina itself, and contains several types of light-sensitive neuron, ganglion cells that conduct light information to the brain, and supporting glial cells.
The ‘retina in a dish’ is by far and away the most complex biological tissue engineered yet.
What's so surprising about the self-directed organization of the stem cells is how the culture started as a patternless collection of cells that weren’t pushed or pressured to become any particular thing. The optic cup's formation depends on some intrinsic, self-organizing program directing the fate and position of cells.
Though the optic cups may look and develop like the real thing, there may be differences between what's synthetic and what happens normally. The team hasn’t shown if the optic cups can sense light or transmit impulses to the brain.
If the technique can be adapted to human retinas (which develop similarly to mouse ones) and proved safe for transplantation, it could offer an unlimited well of tissue to replace damaged retinas.
Retinitis pigmentosa and age-related macular degeneration are the most common causes of blindness in old age, and involve the gradual and normally irreversible destruction of retinal cells.
For now, retinas created from reprogrammed stem cells from patients with eye diseases could be used to screen drugs or test gene therapies.
The study was published today in Nature.
Image: optic cup in a test tube / M. Eiraku and Y. Sasai at RIKEN
This post was originally published on Smartplanet.com