History Made: Regenerated Optic Nerve Cells in Mice
Updated: Apr 17, 2021
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“What we’ve seen is the strongest regeneration of any technique we’ve used before,” Keith Martin, University of Melbourne.
Image: Gene therapy has now taken a new approach on ophthalmology. A student at Cambridge University has successfully regenerated optic nerve cells in mice.
Have you ever wondered when the day would come when scientists would be able to regenerate optic nerve cells? Wonder no longer! In early November, Veselina Petrova, a student at Cambridge University, has successfully conducted experiments using gene therapy to regenerate damaged optic nerve cells.
There have been many past attempts to achieve what used to be considered the “impossible”. Back in 2012, a study conducted by Silmara de Lima et. al. managed to restore limited vision to mice after regenerating the axons of optic nerves. Four years later in 2016, a study conducted by Jung-Hwan A Lim et. al. also used gene therapy in order to regrow sections of retinal ganglion cells, neurons located near the retina.
Even though the research is still in its early stages, this latest study questions whether protrudin, a molecule present in sprouting neurons, can protect cells from damage, and additionally, continue to be produced in damaged eye cells. The approach starts off by culturing optic nerve cells in a dish to increase protrudin production. This experiment showed that cultured nerve cells were able to generate long axons than those that were uncultured. A second experiment was conducted by administering gene therapy with an injection on mice, which also codes for an increase in protrudin production. During experiments, observations were made showing many mice had many surviving nerve cells. Two weeks after the protrudin injection, Petrova’s team also removed whole retinas from the mice. Oddly enough, they exhibited a behaviour called “neuroprotection”, in which the retinas were virtually free from any signs of damage. This was unexpected as retinas removed in such a way often results in them dying in a couple days.
As of now, hypothetically, eye injections are safe for humans, but there are concerns regarding the gene therapy being human-friendly. In addition, the treatment may not be as simple as pumping in more protrudin to regenerate eyesight. In the future, Petrova hopes to observe whether protrudin has the same effect with cultured human retinal cells.
Many cells in the human body can regenerate and divide over and over, but some nerve cells actually do not have this ability. This characteristic of nerve cells is what makes neurodegenerative diseases so complex. In the past, damage to fully-matured nerve cells was virtually irreversible and often resulted in a drastic change of living conditions, such as blindness. However, this discovery has great potential to prevent or help patients recover from a wide range of eye diseases, including glaucoma. If successful, this innovation could even lead to the recovery of other types of nerve cells!