More than 15 million Americans suffer from age-related macular degeneration, a disease that can rob patients of their sight. It starts slowly. Over the course of months or years, lumps of cellular debris and new blood vessels can form in the retina, damaging tissue and causing progressive blindness—and in many cases, the effects of the disease are irreversible.
Researchers at Tufts are trying to improve those odds. They are exploring new ways to replace damaged retinal tissue using cells from an unlikely source: a patient's own dental pulp. "[Dental] pulp cells and retinal cells share a common progenitor in the body," says stem cell biologist Behzad Gerami-Naini, an assistant professor at the School of Dental Medicine, who is leading the research. "As an embryo develops, certain stem cells differentiate into retinal tissue, fat cells, bone cells or tooth pulp—so all those cell types are actually related on some level." Because the cells share the same origin, Gerami-Naini says that it may be possible to "reprogram" them in the lab, gently coaxing them into becoming retinal cells.
The key to this cellular transformation, he adds, lies in manipulating a set of genetic instructions that tell stem cells which genes should be turned on or off at any given time. These instructions, called the "epigenome," effectively act like a series of molecular bookmarks, flagging snippets of DNA that contain the recipe to make a nerve cell, retina, tooth pulp or other specialized tissue. By rearranging those bookmarks, he says, it's possible to alter which "recipe" a cell uses to determine its final form.