Doctors are reversing blindness for the first time

Will there be a cure for blindness soon?

For the first time, researchers have managed to restore vision in blind mice. To do this, they converted maintenance neurons into rods and cones, which represent the light-sensitive structures of the eyes.

In their current study, the scientists at the National Institutes of Health converted so-called maintenance neurons in the eyes so that blind mice could see again.

Many people in the world are blind

Blindness is a condition that affects many people around the world. Almost three million Americans see poorly, and another 1.3 million Americans are completely blind, the experts say. The number of people who suffer from macular degeneration in old age and thereby go blind will double by 2050 and reach around 22 million, the scientists suspect.

Mice regained their eyesight

However, if the newly developed treatment proves successful in humans, many of those affected could regain their eyesight. The scientists used gene injection to transform cells that help transform the shape of the retina into photoreceptors that restore vision in blind mice.

Why do we see worse and worse in old age?

Cells are constantly dying and then being replaced by new cells, but as people age, the rate at which cells die and the rate of exchange slows down, the experts explain. Neurons are not particularly good at regeneration, and this includes light-sensitive photoreceptor cells. This group of highly specialized neurons in the retina that wraps around the back of the eye mainly consists of rods and cones.

What is the role of chopsticks and cones?

Chopsticks take pictures in low light, while cones are sensitive to fine details and colors. Chopsticks allow you to see in low light, but they can also help to preserve the photoreceptors that are important for color vision and high visual acuity, explains study author Dr. Thomas Greenwell of the National Institutes of Health in a press release. Cones tend to die of late stage eye diseases. If rods could be regenerated from inside the eye, this would represent a strategy for treating eye diseases that affects the photoreceptors.

Strengths and weaknesses of the human eye

The human eye is very good at seeing fairly large distances in detail and in a wide range of colors, but our peripheral vision and night vision are nowhere near as good as a cat, for example. In addition, our eyes cannot regenerate as well as, for example, the eyes of zebra fish. Even if the eye is severely injured several times, a zebra fish remains in view, while the rods and cones of people die off as they age. The zebra fish has the advantage here that the so-called Müller glial cells in its eyes, which normally do not react to light, can actually be converted into photoreceptors when they are needed.

Mammals cannot convert glial cells into photoreceptors

However, mammalian glial cells do not have the same malleability, and even if they had the same mechanism that triggers transformation in the eye of the fish, it would only be triggered by injury, which would make treatment difficult for humans. Attempts to regenerate the retina to restore a person's eyesight are counterproductive from a practical point of view. Injuring the retina first to activate the Müller glial cells does not seem to be a perfect solution, explains study author Dr. Bo Chen from the Icahn School of Medicine at Mount Sinai in New York.

Gene injection directed glial cells to divide

The scientists tried to use gene therapy to program the so-called switch function in the glial cells of blind mice without first injuring them. The gene injection instructed the glial cells to divide, the beginning of the regenerative process, the researchers explain. After a few weeks, they gave the mice another eye injection, which caused the new cells to become rods instead of glial cells. The new, converted cells looked like rods, they also communicated with other cells in the retina like rods, the authors explain.

Trying on people in the near future?

Although the mice were born without chopsticks, they could see through the procedure. But just because the chopsticks work doesn't mean that the mice have a fully functional view, the scientists say. Further research by the researchers is now to determine how the mice behave in a labyrinth in order to analyze whether all correct cognitive connections of the seeing mice are working. If this is the case, the scientists want to start transforming human glial cells into rods in the laboratory. (as)

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