Scientists from the University of Michigan Medical School have discovered a signalling system that gives zebrafish the ability to regenerate retinal neurons.
It’s hoped the discovery could one day lead to a technique to encourage human retinas to regenerate. Diseases like macular degeneration, diabetic retinopathy, and glaucoma are all accompanied by the death of neurons in the retina.
It’s hoped the discovery could one day lead to a technique to encourage human retinas to regenerate
While regenerative stem cells have not been identified in the adult human retina, they have been found in zebrafish.
Researchers are investigating how cells called Muller glial cells, responsible for regenerating a damaged zebrafish retina, acquire stem cell properties, the University of Michigan Medical School said in a news release on its website.
Building on their work that identified the cells, a new study reported in Proceedings of the National Academy of Science, led by postdoctoral fellow Dr Sumitra Mitra, and research lab specialist Dr Sulochana Devi investigates whether cells other than dying neurons influence Muller glia’s regenerative response.
Interestingly, these cells are present in both the zebrafish and human retina, and in both species, they contribute to retinal structure and homeostasis; however, only in zebrafish do these cells respond to retinal neurodegeneration by adopting stem cell properties that allow them to regenerate retinal neurons.
With the new study, the University of Michigan discovered a Vegf-Notch signalling system that is activated in the injured retina and connects Muller glia with immune cells and cells lining blood vessels.
Importantly, they found that each of these cell types contributes to the gene expression changes necessary for Muller glial cell reprogramming and acquisition of stem cell properties.
This signalling system is not found in mammals, which might help explain why the human retina does not regenerate.
Soumitra Mitra, Sulochana Devi, Mi-Sun Lee, et.al. Vegf signaling between Müller glia and vascular endothelial cells is regulated by immune cells and stimulates retina regeneration. PNAS. DOI: 10.1073/pnas.2211690119