When a person’s cornea is burned it’s not necessarily the splashed chemicals or hot liquids that causes blindness, but the eye’s recovery. Scar tissue, formed from cells in the white part of the eye, can cover the cornea in a cloudy haze. But researchers have found that cells drawn from another part of the body can correct the problem.
A paper published yesterday in the New England Journal of Medicine brings news of a regenerative stem cell treatment that has had striking success: It restored sight to 82 of 117 eyes with burnt corneas, and worked partially on 14 others. The treatment also seems to have a long-lasting impact; in one patient, the beneficial effect has lasted for ten years and counting.
The treatment offers hope to those who received little benefit from existing therapies–such as artificial cornea replacements, which can also be overpowered and clouded by white-colored cells, or stem cell or cornea transplants from cadavers, which patients can reject.
“[The patients] were incredibly happy. Some said it was a miracle,” said one of the study leaders, Graziella Pellegrini of the University of Modena’s Center for Regenerative Medicine in Italy. “It was not a miracle. It was simply a technique.” [AP]
That technique, first performed in 1995, requires harvesting healthy “limbal stem cells” from the cornea’s border. Stefano Ferrari in Italy then grew these cells into a sheet and grafted them onto the cornea. Since the cells come from the patient and not from a donor, the procedure does not have the risk of rejection present with transplants.
The treatment “is like putting on a biological contact lens,” said Dr. Stephen Pflugfelder, a practicing corneal specialist and professor of ophthalmology at Baylor College of Medicine in Houston, who says the technique works well. A clear cornea–essential to good vision–“is the clear window on the eye,” like a watchglass on a watch, added Pflugfelder, who was not involved with the Italian study but is familiar with its findings. [HealthDay]
For successfully treated patients, vision improved within months, and of those that did not fully regain their sight the treatment still often helped.
Even when not completely effective, the treatment usually alleviated a patient’s sensitivity to light and eye pain, Pellegrini said in a telephone interview. “In any case, the patient has improvement in symptoms,” she said. The researchers were also able to pinpoint which types of cells were more likely to work well. [ABC]
Unfortunately, the technique requires a healthy population of “donor” stem cells from the patient, so it will not work for those who have severely burnt both their corneas (leaving few healthy limbal stem cells). A benefit of the technique is that it requires fewer total stem cells than previous procedures (as ABC reports, about .002 square inches of tissue) since researchers cultivate these sample cells in the lab to make the graft.
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