Scientists at the University of Pittsburgh working with mice showed how stem cells harvested from teeth extracted during routine dental procedures can potentially be used to restore sight in those suffering from corneal blindness. They published their study (“Dental Pulp Stem Cells: a New Cellular Resource for Corneal Stoma Regeneration”) in Stem Cells Translational Medicine.
Corneal blindness afflicts millions of individuals worldwide. It occurs when the cornea becomes scarred and cloudy, and light cannot penetrate the eye to reach the light-sensitive retina. Since corneal scarring is largely irreversible, the most common method of treatment is to graft a new cornea using tissue taken from cadavers.
Given that there is a worldwide donor shortage and that many grafts are eventually rejected because they are not the patient’s own tissue, researchers have been looking for a new source for such tissue or a new way to regenerate the patient’s own cornea. (The current failure rate of corneal grafts is about 38% after 10 years, primarily due to tissue rejection.)
The University of Pittsburgh team, led by James L. Funder burgh, Ph.D., and Fatima Styled-Picard, Ph.D., both in the department of ophthalmology, decided to focus on adult dental pulp stem cells (DSC) as a possible solution.
“If we could generate an engineered cornea using tautologies cells, which are the patient’s own cells, and then use that to replace scarred tissue, we could bypass the limitations of current treatments,” Dr. Funder burgh explained. “We thought dental pulp might be the answer, as other studies have proven that DSC can differentiate into various other cells and they already have a similarity to cornea tissue as they both develop in the embryo stage from the cranial neural crest. That led us to believe that we might induce DSC to become corneal cells, too.”
The team began by collecting DSC from molar teeth discarded after routine extractions at the university’s dental school and then treated the cells in a special solution that caused them to differentiate into corneal cells (nematocysts). When they tested the DSC-generated nematocysts they found they had the same properties as those grown naturally in the human eye.
They then seeded the cells onto a corneal-shaped magnifier substrate to see if they could engineer corneal tissue. Four weeks later, the cells had grown into a structure that mimicked the complex organization of an actual cornea.
Their final task was to evaluate how the DSC-generated nematocysts would perform by labeling them with a dye (for tracking purposes) and then injecting them into the right eyes of mice. (The left eye of each animal was injected with medium only, as a control.) When they tested the mice’s eyes five weeks later, they found that the DSC-generated nematocysts had remained in the corneas and behaved similar to natural nematocysts. Their corneas were clear, and there were no signs of rejection.
“These findings demonstrate a potential for the clinical application of PCs in cellular or tissue engineering therapies for corneal stoma blindness,” wrote the investigators.