With the Help of Stem Cells, Those Who Were Blind Can Now See
Italian researchers have reported success with a treatment that uses stem cells to grow corneal tissue in dozens of people who were blinded or suffered eye damage due to chemical burns. According to the Bureau of Labor Statistics, there were about 2,850 work-related chemical burns to the eyes in 2008 in the United States, mostly involving heavy duty cleansers or other substances.
In the study, Graziella Pellegrini and colleagues at the University of Modena’s Center for Regenerative Medicine in Italy, 106 patients were treated between 1998 and 2007. Most had extensive damage in one eye and many had been blind for years and had had unsuccessful operations to restore vision.
The doctors first removed scar tissue from the cornea of the damaged eye. They then harvested stem cells taken from the limbus (the rim around the cornea) of the healthy eye and multiplied them in a laboratory setting. The cells were then grafted over the injured cornea. The stem cells were able to grow new corneal tissue to replace what had been damaged. Because the stem cells were taken from the patient’s own eyes, no anti-rejection therapy was required.
The researchers followed the patients for an average of three years, and up to a decade in some cases. Though some patients needed more than one graft, the treatment worked completely in 82 of the patients and partially in 14 others – though their vision had improved, they still had some cloudiness in the cornea. Patients also reported less light sensitivity, itching and pain which are common after chemical or thermal burns.
Pellegrini and colleagues have performed corneal transplants in about 250 patients over the last decade using the stem cell technique, but it remains experimental and is not being done in the U.S.
Corneal injuries and diseases are the leading cause of visits to eye care clinicians, according to the National Eye Institute. Currently, people with eye burns can get an artificial cornea, a procedure that carries complications such as infection and glaucoma. They can also receive stem cells from a cadaver, but the transplant requires taking medications to prevent rejection. About 40,000 people each year undergo cornea transplants according to the American Academy of Ophthalmology.
This technique would not help people with damage to other areas of the eye, such as the optic nerve or retinal macular degeneration. Nor would it work in people who are completely blind in both eyes, because doctors need at least some healthy tissue that they can transplant.
The study is published in the June 23 online issue of the New England Journal of Medicine.