A revolutionary technique to grow eye cells from scratch offers fresh hope for millions at risk of blindness.
Scientists at Duke University have discovered a way of coaxing adult cells to transform into specialised blood vessels that are key for eye health.
When injected into the eyes of mice with retinal diseases, the lab-grown ‘retinal endothelial’ cells integrated into damaged tissues and restored their function.
The researchers say these cells could be the basis of new breakthroughs in treatments for vision loss and eye disease.
These specialised blood vessel tissues keep the eye healthy, but their degeneration leads to diabetic retinopathy – a complication of diabetes and the leading cause of vision loss in the UK.
Labs currently rely on cells harvested and grown from real patients – making samples for research expensive and hard to come by.
However, the researchers’ innovative technique could change everything by allowing scientists to make their own retinal tissue on demand.
Co-first-author Parker Esswein says: ‘While there are sources of retinal endothelial cells, being able to grow a continuous supply from scratch could offer many advantages for those working in the field.’
Scientists have developed a way of growing the specialised blood cells found in our eyes from scratch. When these cells are healthy (right), they support healthy eye function, but their deterioration (left) leads to vision loss
Just like the brain, the eye is protected by a blood barrier that controls how much fluid, oxygen, sugar, and other chemicals can reach the sensitive tissues beyond.
This barrier is made up of retinal endothelial cells, specialised cells that form the inner layer of blood vessels.
If these cells degenerate or the barrier weakens, it can lead to lots of different diseases that ultimately culminate in vision loss.
Since these cells don’t grow anywhere else in the body, scientists’ understanding remains limited, and their ability to develop new treatments is hindered.
But now, in a paper published in the journal Nature Biomedical Engineering, the researchers describe a new way of making these cells in the lab.
The researchers tested the lab-grown cells on mice that had retinal diseases but had not yet started to lose their vision.
The cells quickly integrated into the damaged tissues and helped form strong blood vessels and a healthy blood barrier.
Mr Esswein says: ‘The tests showed that these lab-grown cells have promise for preventative treatments, especially since they should be easier and cheaper to obtain using our technique.’
When injected into the eyes of mice with retinal diseases, the lab-grown ‘retinal endothelial’ cells integrated into damaged tissues and restored their function. Pictured: A mouse retina before treatment (right) and after treatment (left)
Instead of starting with retinal endothelial cells taken from patients, their method begins with special cells called induced pluripotent stem cells (iPSCs).
These are mature adult cells that have been chemically reprogrammed into primal versions of themselves, capable of transforming into any type of cell in the body.
The hard part is finding the right combination of chemical treatments to coax these shapeshifters into the exact form you want.
Mr Esswein and Dr Ying-Yu Lin, now at Johnson & Johnson Innovative Medicine, took commercially available stem cells and used a well-established procedure to turn them into standard endothelial cells.
They then concocted a unique cocktail of chemicals called ‘growth factors’ that told the cells to turn themselves into the specific type of endothelial cells found in the eye.
Incredibly, in the lab, these cells were able to form the exact same type of cell networks that they do in the body.
And when the researchers created the low-oxygen, high-glucose environments that damage the real blood barrier, their lab-grown versions degraded in the same way a real patient’s would.
That is a hugely important finding, because it means scientists will be able to use these cells to investigate the mechanisms behind eye disease and even test potential cures.
Mr Esswein says: ‘While our benchtop experiments did not attempt to model a wide variety of specific eye diseases in these studies, we’re confident we can create excellent human tissue models in the lab to help better understand these diseases and uncover therapies.’
More excitingly, these stem cells could also be the basis of a new preventative treatment themselves.
Moving forward, the researchers are planning to explore these potential uses for their retinal endothelial cells both in their laboratory and through emerging industry partnerships.
This could ultimately lead to the development of new treatments for retinal diseases that might save millions from vision loss.
