Retinal damage in humans is a major cause of blindness that afflicts many people around the world. Unfortunately, the retina is one of the few tissues that humans cannot repair.
However, unlike us, some animals, including Danio-rerio, have the ability to restore tissue that is key to vision. We share 70% of the genes with this tiny animal, which is why scientists began to study them and found that some of these genes are responsible for retinal repair in Danio-Rio.
“Regeneration seems to be a key feature, and humans have lost that ability on the path to evolution,” said Seth Blackshaw, a neuroscientist at Johns Hopkins University.
The retina is the part of our eye that responds to light. It contains sticks and flasks that absorb light, as well as nerve cells and synapses – they transmit information about light to the brain.
During the formation of the human body, the retina is formed from the brain – it is actually the brain tissue that terminates in front of our eyes and forms the central nervous system.
Another constituent of the retina is the Mueller cells (glial cells of the retina) that control the work of the nerve cells in it. They clear the retina of debris, store important molecules, and also seek help from the immune system if needed.
In the case of some fish and reptiles, these Mueller cells provide retinal repair in the event of injury, though not in mammals. The team of researchers looked at genes associated with Mueller cells in Danio-ries, chickens, and mice – they observed cell responses to damage in these three species.
Activated genes were involved in repairing the damage – they called in immune cells to clean the damaged tissue and fight the potential threat. However, after this process, the network that prevents these genes from working is activated only in the case of brains. Consequently, they were unable to transform into the cells that formed the retina.
The researchers also observed that after retinal damage in all three species, Mueller cells stopped producing a specific protein that inhibits these genes. However, it soon appeared in mice, so the researchers artificially stopped the production of the protein, and the retina of the adult mouse began to recover after injury.
This is, of course, a significant achievement, although there is still much work to be done in humans before retinal regeneration. According to the team, this process is very complex and a lot of different mechanisms need to be studied. However, after a lot of research and experimentation, the retinal recovery procedure may become a reality.