Stem cells have slowly emerged as the answer to diseases concerning loss of cells and weakening of organs. Now, stem cells are being used to restore vision in patients with severely impaired vision.
Four people received the stem cell treatment, three of whom experienced improved vision, which lasted for over a year. The four patients are the first to receive corneal transplants from reprogrammed stem cells.
How the cornea can be damaged?
The cornea is the outermost, transparent layer of the eye. It is maintained by a group of stem cells found in the limbal ring— a dark ring just outside the iris. Autoimmune disorders, genetic diseases, or trauma to the eye can deplete the reservoir of stem cells, leading to a condition called limbal stem cell deficiency or LSCD. This leads to the formation of scar tissue over the cornea, often leading to blindness.
The treatment typically involves corneal transplants from donors with healthy eyes. However, the process is both invasive, and the outcomes are uncertain. Transplants are also often rejected by the body’s immune system.
How reprogrammed stem cells restore vision?
What makes this specific stem cell therapy special is the fact that it doesn’t induce a hostile immune response or formation of tumors, making the procedure safe. Kohji Nishida, an ophthalmologist at Osaka University in Japan, and his colleagues reprogrammed blood cells taken from a healthy donor into an embryonic-like state, forming induced pluripotent stem cells or iPS cells, which were then further transformed into thin, transparent sheets of corneal epithelial cells. The team worked with two men and two women with LSCD in both eyes. As a part of the surgery, the team removed the scar tissue that had accumulated over the cornea in one eye. Next, the team stitched epithelial corneal cells derived from a donor and placed a soft contact lens on top for protection.
Two years after the transplant, the patients have not faced any severe side effects. They experienced immediate improvement in vision. Reduction in the area of cornea damaged by LSCD was also observed. However, slight reversals toward LSCD were noted in one person.
It is still not clear as to what improved the vision of these four patients. The transplanted cells might have rejuvenated the cornea or might have proliferated in the corneal region itself. Removal of the scar tissue during surgery aided in the cure as well.
The promising results of this novel method are cause for excitement. Nishida says that he plans to initiate clinical trials in March. There are multiple other iPS-based trials underway to treat eye diseases. Kapil Bharti, a translational stem-cell researcher at the US National Eye Institute, National Institutes of Health, in Bethesda, Maryland, says, “These success stories suggest we are headed in the right direction.”
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