Retinal Pigment Epithelial Transplant Geographic Atrophy

05/23/2017

Healthy Living, May 23, 2017
Michael Johnson, MD – Eastern Maine Medical Center

Johnson.jpgFor years, people were throwing away cells that could bring eyesight to the blind. These dark, blackened cells looked like spots of contamination in the petri dishes in which researchers around the world were carefully nurturing highly purified colonies of human stem cells.

Now we realize that what appeared to be specks of dirt were actually some of the key cells that enable people to see.

In those seemingly contaminated petri dishes, stem cells had transformed themselves into the specialized cells that support the health of the retina — known as retinal pigment epithelial, or RPE cells. The death of RPE cells is one of the primary contributors to age-related macular degeneration, the leading cause of blindness in the elderly in the Western world.

Delivering these RPE cells into the eyes of patients with the most common form of the disease —the atrophic, or dry type of age-related macular degeneration — in a phase 1 clinical trial, scheduled to begin in early 2015 with funding from the California Institute for Regenerative Medicine (CIRM).

The University of California, Santa Barbara, is helping with the differentiation of RPE cells, Caltech is assisting with the development of the synthetic membrane, and City of Hope is manufacturing the actual product that will be implanted into patients in the clinical trials.

Sheet transplants restore lost visual responses in several retinal degeneration models in the superior colliculus (SC) corresponding to the location of the transplant in the retina. They do not simply preserve visual performance – they increase visual responsiveness to light. Retinal progenitor sheet transplantation provides an excellent model to answer questions about how to repair and restore function of a degenerating retina.

In total, more than two million Americans, or about two percent of the population, suffer from the advanced form of age-related macular degeneration. Each year, nearly 300,000 of these patients in the U.S. alone watch their worlds vanish as the disease blinds them. Macular degeneration destroys their central vision, leaving them unable to recognize faces, drive, read, and lead independent lives.

Currently, there is no treatment for the atrophic form of the disease, which the new RPE implants will target.