Age-related macular degeneration (AMD) is the most common cause of retinal degeneration; it is the leading loss of vision in people over the age of 50. AMD causes the degeneration of the part of the eye responsible for providing sharp, central vision. A layer of cells at the back of the eye, called the retinal pigment epithelium (RPE), provides support, protection, and nutrition to the light sensitive cells of the retina. Dysfunction of these cells plays a critical role in blindness and vision loss in AMD. Initially, the disease causes distortion in central vision; eventually, it can lead to legal blindness.
Vision loss may progress slowly or quickly; however, over time, all victims develop blurred or blank spots in their vision, making it increasingly more difficult to perform daily tasks and recognize faces.
By 2020, over 450,000 Californians will suffer from vision loss or blindness due to AMD. Treatment is extremely expensive, and not altogether effective. Costs continue to skyrocket. The cost of AMD per patient per year can exceed $25,000.
California’s stem cell research agency, the California Institute for Regenerative Medicine (CIRM) has awarded more than $106 million in funding to vision loss-related projects.
One of the leading research projects, which received a $19 million CIRM Disease Team Grant, is taking place at the University of Southern California. This project  suggests that new cells, derived from embryonic stem cells, can be transplanted to overcome the loss of the layer of cells at the back of the eye. Damaged retinal cells could then be regenerated and restored.
This study is led by co-Principal Investigators Mark Humayun, MD, PhD, Professor of Ophthalmology, Biomedical Engineering and Cell and Neurobiology at the Keck School of Medicine of USC, and David Hinton, MD, Professor of Pathology, Neurological Surgery and Ophthalmology at the Keck School of Medicine. The USC team of researchers also includes scientists from University of California at Santa Barbara and City of Hope.
The team proposes to use embryonic stem cells to produce the support cells, or retina pigment epithelium (RPE) cells, needed to replace cells lost in age-related macular degeneration (AMD). Research has shown that the loss of RPE cells, located in a thin sheet at the back of the eye, leads to AMD. To restore the RPE cells, the USC team proposes growing thin sheets of stem cell-derived cells to be surgically implanted into the eye, replacing diseased sheets and restoring the photoreceptors, the light sensitive cells of the retina.
“This research could be a game-changer in AMD,” said Keck School Dean Carmen A. Puliafito, MD, MBA, an ophthalmologist specializing in retinal diseases. “Estimates indicate that by 2020, more than 450,000 people in California alone will suffer vision loss or blindness because of this disease, and the innovative approach by Drs. Humayun and Hinton shows distinct promise.”
With CIRM funding, the team is proceeding with a Phase 1 human clinical trial to test the surgically implanted cell sheets. Hopefully, this work will result in successful restoration of sight in currently untreatable cases of AMD.
Dr. Mark Humayan (University of Southern California) hopes that “…vision loss or blindness due to AMD…can be overcome by transplanting new cells derived from embryonic stem cells.”
“Stem cell research on the eye is moving quite quickly,” says Ingrid Caras, a CIRM science officer. “The eye is an attractive study target — it’s a small, contained area with no immune rejection of implanted cells, and it’s much easier to monitor what’s happening in the eye.”
Selected disease and research progress information provided by the California’s stem cell research funding agency, the California Institute for Regenerative Medicine (CIRM). Visit www.cirm.ca.gov for more updates.
 “Phase 1 Safety Assessment of CPCB-RPE1, hESC-derived RPE Cell Coated Parylene Membrane Implants, in Patients with Advanced Dry Age Related Macular Degeneration.” California Institute for Regenerative Medicine. https://www.cirm.ca.gov/our-progress/awards/phase-1-safety-assessment-cpcb-rpe1-hesc-derived-rpe-cell-coated-parylene