Rosalinda Barrero has often been mistaken for a rude snob. She has the habit of not saying hello or even acknowledging the presence of acquaintances that she passes around town. But in fact this kind, loving mom of three has been steadily losing her vision over a lifetime. And she doesn’t seem blind because people are still vaguely visible as shadowy ghosts but their faces are unrecognizable.
Barrero is stricken with retinitis pigmentosa (RP) an incurable genetic disease that gradually destroys the light sensing nerve cells, called photoreceptors, located in the retina at the back of the eye. In October, Rosalinda and her husband German spoke to the CIRM governing Board about the devastating impact of RP on their lives and their excitement about a soon to begin CIRM-funded stem cell-based clinical trial for the treatment of RP. The project is headed by UC-Irvine associate professor Henry Klassen, MD, PhD, who also spoke to the Board. Videos of their presentations are now available on our website and below:
Over 3000 known genetic mutations can give rise to RP. These mutations lead to the gradual deterioration of the so-called rod photoreceptors. These rod cells specifically provide our night vision — like on a moonless night. Rosalinda clearly remembers her childhood struggles with night blindness on Halloween:
“I didn’t like trick-or-treating because I couldn’t see in the dark. I ‘d say ‘this is not fun! I’m tripping! I’m losing all my candy!’ I wanted to stay home and hand out candy”
Unfortunately the disease doesn’t stop there. As the rods continue to die off another type of photoreceptor, the cone cells, become innocent bystanders and also gradually deteriorate later in life. As Dr. Klassen explained, it’s the cone cells that are critical for our sight:
“The cones are what humans use for almost all of their vision. Even at night when you’re driving a car with headlights you’re using mainly your cones. So if we could preserve the cones we can really help the patient.”
With the support of a $17 million CIRM Disease Team grant, Klassen and his team anticipates starting a stem-call based clinical trial in early 2015 with the ultimate aim of healing those cone cells in RP patients. The therapy uses a type of immature stem cell of the retina called retinal progenitor cells. The proposed approach relies on the injection of the cells into the jelly of the eye near the retina to promote indirect healing. Klassen explained the project rationale to the Board:
“So we’re talking about little clusters of cells that could fit on the head of a pin in the jelly of the eye and they’re just floating there. And what are they going to do? Well they just sit there and secrete all the factors they normally secrete during retinal development and diffuse into the retina. Once in the retina we believe [based on animal studies] those factors are going to reprogram the photoreceptors into becoming functional again instead of going down that road where they’re going to commit suicide.”
Rosalinda is beyond thrilled with the prospect of being a recipient of this candidate therapy. Her husband German echoed her hopefulness to the Board:
“Even though it’s not a deadly disease, [the therapy] would be life-changing not only for Rosie it would be for everyone around her. “
To learn more about CIRM-funded research related to blindness, visit our fact sheet.