A new technique using stem cells could restore vision in mice who have end-stage eye disease, a condition that is believed to bring irreversible loss of vision.
Researchers used stem cells to grow new retinal tissue in a lab, and then transplanted that tissue in mice that had late-stage retinal degeneration. More than 40 percent of the mice had the opportunity to see the light as the result of the procedure, the researchers said.
This is the first time that researchers have successfully transplanted cells that sense light, the retina light receptors, so these cells connect with the host of the nervous system and send signals to the host of the brain, the researchers said.
“We were initially very excited to see that the transplants do robust respond to light,” Dr. Michiko Mandai, the first author of the paper and a deputy project leader of the RIKEN Center for Developmental Biology in Japan, told live Science.
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The researchers hope to eventually increase the number of connections between the cells in the host degenerated retina and stem cell transplants, Mandai said. This can allow the mice not only light, but also a major figure or movement, Mandai said.
The retina is the layer of tissue at the back of the eye that actually senses light and gives signals to the brain, where the information is processed and an image is observed . In individuals with retinal degeneration, the light sensitive cells are gradually lost, ultimately leading to total blindness, Mandai said. Age-related macular degeneration , the most common type of retinal degeneration, affects approximately 15 million people in the US and 170 million people worldwide.
In the study, researchers converted skin cells from an adult mouse in the mouse induced pluripotent stem cells (iPSCs). The scientists then converted these stem cells into the retina of the tissue and the transplanted tissue in mice that had late-stage retinal degeneration.
The researchers used a so-called shuttle avoidance test to determine whether the mice could see the light. The test includes a sound – and light-insulated box with two compartments, separated by a wall with an opening that allows the mice to move between the two compartments.
A mouse is placed in the box and trained to recognize that a simultaneous beep and light signal is a danger of electric shock. The mouse can avoid the shock by moving to the other room. In the study, when the mice were trained to avoid the shock, only the light (and not the beep) was used as a warning, to test whether the mouse could see the light.
In the experiment, after retina transplantation , four of the 10 mice with transplants in both eyes, and five of the 11 mice with a transplant in only one eye may respond to the light signal, according to the findings, published Jan. 10 in the journal Stem Cell Reports.
It is unclear whether the new technique can be applied in humans, and testing it is probably a long way to go, the researchers said. One aspect of the health of the human being to consider is that, while the mice in this experiment were able to respond to light, a month after the retina and the transplant of the human retina takes a longer time to mature, the researchers said in a statement . So, it may take up to five or six months for a transplanted retina in people to start to respond to light, they said.
In addition, the researchers still need to test whether the same procedure would work in humans, the scientists said.
“From a clinical point of view, although we think that these results are promising, the human eye may have a different environment of mice, and [the questions of] whether they accept the retina transplants and making connections with transplants are yet to be tested,” Mandai told Live Science. “We would have the answers only in [a] man study.”
Originally published on Live Science .