Reversing blindness is a challenge for science. It has been investigated for years from different sides. A group of American scientists published a few months ago very promising results after treating patients with hereditary retinal degeneration with an experimental “gene editing” therapy. Most improved their vision after modifying a gene mutation.
Now, researcher Pia Cosma, from the Barcelona Center for Genomic Regulation (CRG), wants to open a new avenue of exploration. He has proposed creating a synthetic retina from stem cells that he will first test in mice. If it works, the idea is to translate it to humans with retinitis pigmentosa, a degenerative and rare disease that causes vision loss little by little. The project, financed by the La Caixa Foundation with almost one million euros, will be carried out in collaboration with biotechnologists from the Do Minho University (Portugal).
For those who have just landed on this pathology: what is retinitis pigmentosa and what does it cause in patients?
It is a rare degenerative pathology – it affects one in every 3,000 to 5,000 people – and patients progressively lose retinal photoreceptors. These are cells that convert light into electrical signals that are transmitted to the brain. That is, it allows images to be created in the brain. The retina is like a small brain that has different strata of neurons, different layers.
Is there any treatment currently to prevent this degeneration from happening?
There are options to make the degeneration slower or progressive but not to stop it. The speed depends on the mutation, but there is a time when it is not seen. Our research is designed for those patients in an advanced stage, if it really turns out as we hope. The only thing being tested now is gene therapy for specific mutations, that is, some solutions for some patients. But only for some.
This is where the core of their project comes into play: creating a synthetic retina. How is this done in the laboratory?
We are going to create a specific type of retina that is a kind of organoid embedded in a biostructure that can create an optic nerve. How? Through the reprogramming of stem cells, which are pluripotent, we create a tissue similar to the retina inserted in a type of scaffold that encapsulates it and favors the formation of an organoid suitable for transplantation. That is, it connects with what still works.
The retina doesn’t die completely, then?
No, the retina does not lose all its functions with this disease because it has different layers of neurons. The most affected are the photoreceptors but they synapse with the interneurons and ganglion cells. When there is strong degeneration, the other neurons are somewhat damaged. However, they still work somehow.
Do they have to test it on mice first?
Yes, when we achieve this we will transplant it into mouse models in that degenerated part, but which still maintains the connection with the brain. There we will see how it works and if it is solved. We will use stem cells from mice and humans as well.
If it works, will it work for more pathologies or just for this one?
This project could solve other types of pathology that involve photoreceptor degeneration. And, furthermore, since we will make an organoid that has an optic nerve, we could study pathologies related to damage in this area, such as glaucoma. For now we have chosen retinitis pigmentosa because we know it well. I hope we succeed.
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