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Treating and Restoring Vision Loss

Alanis Acosta

October 5, 2020          

 

          Elders are constantly reminding us to enjoy our youth while we can, and this is for a reason. Even though most of us do not like to fathom the idea of being old, age eventually catches up to everyone. Along with it comes many diseases and vulnerabilities, such as vision degeneration.

          The evolution of blurred eyesight due to aging occurs in the retina, which is a thin layer of tissue at the back of the eye responsible for translating light information to signals that are then processed by the brain into sight. Researchers from the Harvard Stem Cell Institute have developed strategies and therapies to treat vision loss, already proven successful in the experimental stage. In one experiment, they were able to transplant retina stem cells derived from an adult mouse skin cell to another mouse with retina deterioration. The stem cells instantly traveled to the mouse’s brain correctly, significantly improving its vision. Scientists’ explanation is that they have discovered a protein that breaks down the outer surface of the impaired retina and allow the new and healthy cells to incorporate. In addition to transplantation, the Harvard Institute has also been researching the natural healing effect that fish can have on the retina. Müller cells in fish, which are one of the dominant glial cell types in the retina, have the capability to regress to its original stem cells form and repair damaged eye tissue. Mice and humans have Müller cells as well, except that these lack the regenerative skill. Investigators at the university are still studying the chemical compounds to make this possible.

          Just like there is successful ongoing research about the restoration of retinas, there is a stem cell therapy for the cornea as well. As the protector of the eye’s outer surface, the cornea also requires constant regeneration in order to preserve a clear surface. Surrounding the cornea, there is a dark rim of tissue known as the limbus, which contains cornea-restoring stem cells. If an eye is injured, a transplant can occur using the healthy stem cells from the other eye, but this process has extensive limitations. First off, a small number of cells can be actually used for the transplant, since the healthy eye could be compromised. Second, if there is a genetic disease, both eyes are affected by stem cell deficiency and the transplant would have to be from another donor, risking rejection.

          Moreover, the goal of these scientists is to purify the stem cells so that they can be transplanted without any mix with other cells. In 2014, researchers were able to identify the protein ABCB5 which helped in the process as this molecule was solely expressed on the surface of the stem cells. In the study, they discovered that the mice without ABCB5, did not develop accordingly; while the ones that received the transplant with the protein, generated clear corneas. “We were able to prospectively isolate the cells and demonstrate that they possess a stem cell functionality”, states Markus Frank (“Restoring Vision”). Currently, the doctors are working on implementing this therapy on patients with a clinical trial. “This could be an enormous opportunity to create an off-the-shelf cell product. If you have stem cells ready in a tube that you could transplant without having to match the donor and patient’s immune systems, the treatment would be quicker and more universally accessible,” said Natasha Frank (“Restoring Vision”).

 

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