Three people with severely impaired vision who underwent stem cell transplantation experienced significant vision improvement that lasted for more than a year. A fourth patient also experienced an improvement in vision, but the result was not stable. These four people were the first patients to receive stem cell transplants to treat damaged corneas — the transparent outer surface of the eye.
«The results justify expanding the treatment to more patients,» says stem cell researcher Jeanne Loring of the Scripps Research Institute in California.
The outer layer of the cornea is supported by a supply of stem cells in the limbal ring around the iris. When these cells are depleted — a condition known as limbal stem cell deficiency (LSCD) — scarring forms in the cornea, which can lead to blindness. This can be caused by trauma to the eye or by autoimmune and genetic diseases.
Existing treatments for LSCD are limited: they usually involve transplanting corneal cells from the patient’s healthy eye, which is a complex procedure with uncertain outcomes. If both eyes are affected, corneal transplants from deceased donors can be used, but they can be rejected by the immune system.
Ophthalmologist Koji Nishida from Osaka University in Japan and his colleagues took a different approach, using induced pluripotent stem cells (iPS). They took blood cells from a healthy donor, reprogrammed them into an embryonic-like state, and transformed them into a thin, transparent layer of corneal epithelial cells.
From June 2019 to November 2020, the team recruited two women and two men aged 39 to 72 with LSCD in both eyes. During the surgery, the team removed scar tissue from the affected cornea of one eye, applied donor epithelial cells, and covered the area with a soft contact lens.
Two years after the transplantation, none of the patients had any serious side effects. The transplants did not form tumors — a known risk when using iPS cells — and were not attacked by the patients’ immune systems, even in those who did not take immunosuppressive drugs. Importantly, the transplants were not rejected by the body, but more procedures are needed to confirm their safety.
After the transplantation, all four participants had improved vision and reduced corneal damage. Three of them maintained the improvement, while the fourth experienced some deterioration over the course of a year.
The reason for the improvement in vision is still unclear. It may be the result of the multiplication of the transplanted cells or the promotion of the patient’s own cells to regenerate the cornea.
Clinical trials are planned to begin in March to evaluate the effectiveness of the method.
Source: nature