Retinal Pigment Layer Implantation Stopped Patients’ Vision Loss

Scientists at the Mount Sinai Medical Complex in New York and their colleagues at the National University of Singapore have proposed the use of cadaver retinal stem cells to treat blindness caused by damage to the retinal pigment epithelium. They talked about their discovery in more detail in an article in the journal Stem Cell Reports.

Pigment epithelium is a layer of the retina that provides photoreceptors with nutrients and helps to get rid of waste membrane discs with visual pigment. As we age, and for other reasons, its damage leads to visual impairment and loss in the future.

Macular degeneration, a type of epithelial dysfunction, affects about 200 million people worldwide.

Earlier studies have shown that retinal transplantation can be quite effective against it, but due to the complexity of the operation, this procedure has rarely been used. As cell therapy has developed, scientists have suggested that its methods may be useful in the treatment of blindness.

The researchers used retinal stem cells obtained from two deceased elderly people. They transplanted them into the macaque macaque – the place of the greatest visual acuity in the retina – nine macaques. The experiment has so far been carried out on healthy animals in order to understand whether such a transplant is possible at all. The cells successfully engrafted and no serious side effects were observed for three months.

Moreover, the transplanted cells were able to take over the functions of the pigment epithelium of the retina of monkeys, which makes it possible to use this method in the future to combat blindness.

“We have demonstrated that retinal pigment epithelium derived from human cadavers is capable of at least partially taking over macular function in primates,” says paper author and cell biologist Timothy Blenkinsop. “Cells obtained from a dead donor can be safely transplanted under the retina and compensated for its function in the host, so their use to combat vision loss in patients with retinal diseases looks very promising.”

Scientists warn that clinical trials on humans are still a long way off – first you need to find out what the procedure has long-term consequences and how safe it is for humans. The next step on the way will be an experiment to treat monkeys with blindness due to dysfunction of the pigment epithelium.

It is relatively easy to obtain stem cells from the eyes of the dead – many people sign consent to posthumous eye donation. If the new technique turns out to be effective, doctors will be able to help millions of people around the world, the authors of the work hope.

“The results of this study suggest that such a transplant is safe, and this is a strong argument in favor of clinical trials of the approach in humans, – notes Blenkinsop. “But more research is needed first. Future work should first examine whether stem cells obtained from corpse eyes can restore vision in non-human primates, and only then move on to humans.

Several years ago, Japanese scientists managed to partially restore the patient’s vision with the help of skin stem cells. A 70-year-old woman was diagnosed with age-related macular degeneration. The patient underwent treatment in 2014, but the results of the work were presented only two years later, when scientists were convinced of the success of the operation.

To restore the woman’s vision, scientists used a piece of skin from the patient’s hand and reprogrammed its cells into induced pluripotent stem cells that can turn into almost any type of tissue.

And in the United States, ophthalmologists have suggested using Viagra to combat blindness. Macular degeneration in 90% of cases is associated with vascular pathologies, and Viagra, as it turned out, can improve blood flow in the eyes.

For two years, five elderly participants in the experiment received two tablets of the drug per day. During this time, one of them has improved vision, while the rest have stopped degenerative processes.

There are other drugs available to slow retinal degeneration, but they must be injected into the eye.