Stem Cells Slow Retinal Degeneration in Dry AMD Clinical Trial
A clinical trial for a human neural stem-cell therapy for people with dry age-related macular degeneration (AMD) has shown encouraging interim results. The rate of geographic atrophy — the loss of photoreceptors and supportive cells known as retinal pigment epithelium — was reduced by 70 percent in treated eyes versus untreated of the first seven participants. Also, the patients demonstrated stable or improved contrast sensitivity — the ability to distinguish objects of different brightness and/or colors — in treated eyes.
StemCells, Inc., a California-based developer of human neural stem cell therapies, launched its safety-oriented Phase I/II study at the Retina Foundation of the Southwest in 2012. The treatment has had a favorable safety profile thus far. The interim study results are based on follow-up exams of at least six months.
“Our hope and expectation at this early juncture is that the treatment is safe,” says David Birch, Ph.D., the study’s lead investigator who is also funded by the Foundation Fighting Blindness. “But we are very pleased with the vision improvement and slowing of retinal degeneration.”
He notes that the people currently in the trial entered with relatively poor visual acuity, 20/400 or worse, and that the next group of patients to be enrolled, those with 20/320 to 20/100, will hopefully have more comprehensive visual assessments.
The therapeutic stem cells are delivered underneath the retina of the participants’ most affected eye through an injection. Doses of 200,000 and one million cells have been delivered thus far.
Based on prior research, scientists believe that human neural stem cells provide sustained release of proteins that keep the retina healthy and prevent or slow degeneration. Ray Lund, Ph.D., a stem-cell scientist previously funded by the Foundation Fighting Blindness, conducted laboratory research that made this clinical trial possible.
“While these results are preliminary, they are good news for patients with dry AMD and the advancement of stem-cell therapies for other retinal conditions,” says Stephen Rose, Ph.D., chief research officer at the Foundation. “We have no treatments for dry AMD, the far more prevalent form of the condition, so the need to save vision is great.”
AMD affects 10 million people in the United States with approximately 90 percent having the dry form.