Human Study to Begin for Stem-Cell Therapy Designed to Preserve Retina
A clinical trial for a retinitis pigmentosa (RP) stem-cell therapy developed at the University of California, Irvine (UCI) has received authorization to launch from the U.S. Food and Drug Administration (FDA). Sixteen people will be enrolled in the safety-focused study, which will also monitor changes in visual acuity and retinal sensitivity. Trial participants will receive injections of 500,000 or one million cells.
UCI researchers Henry Klassen, M.D., Ph.D., and Jing Yang, M.D., Ph.D., developed the emerging treatment, which is aimed at preserving vision in people with RP and, potentially, other retinal conditions. They also co-founded the company jCyte, Inc. to advance it toward commercialization. Baruch Kuppermann, M.D., Ph.D., chief of UCI’s Retina Service, will inject the cells into patients.
Known as human retinal progenitor cells (hRPCs), the therapeutic stem cells are similar to those developed by ReNeuron, which recently received FDA authorization to launch a clinical trial for its RP treatment. Both jCyte’s and ReNeuron’s hRPCs are more mature than embryonic stem cells, but haven’t completely developed into photoreceptors, the cells in the retina that make vision possible. However, there are two key differences between the two therapies.
First, UCI’s hRPCs are used to release neuroprotective proteins, also known as growth factors, to preserve cones, the retinal cells that enable people to read, perceive colors and see in lighted conditions. While the ReNeuron hRPCs are also designed to preserve cones, they may also develop into new photoreceptors and integrate into the patient’s retina to restore vision.
Second, the UCI treatment will be injected into the patient’s vitreous, the gel-like substance that fills the middle of the eye. The ReNeuron therapy will be injected underneath the retina, a delicate procedure that carries more risk for damage or complications.
Dr. Klassen says that his team’s approach isn’t as complex as ReNeuron’s, which provides them some advantages. “Delivery is simple and easy on the patient. The cells don’t have to integrate into the host tissue to be effective, which also means we can potentially re-dose patients at a later time,” he explains. “Because the cells will be floating in the clear vitreous gel, we can directly visualize them inside the eye using a standard slit lamp or indirect ophthalmoscope and easily monitor their status, much as we could in a Petri dish.”
Though vision preservation is the primary goal of the UCI therapy, Dr. Klassen believes there’s potential for resurrection of cones that have stopped processing light, but haven’t fully degenerated. “Cone restoration would be a great thing,” he says. “We’re hoping to observe that if it occurs.”
Dr. Klassen became interested in cellular therapies for the retina in the late 1980s while doing graduate studies in the lab of Ray Lund, Ph.D., a stem-cell pioneer previously funded by the Foundation. “At first, I was attracted to the CNS [central nervous system] because it was a huge area of unmet medical need. Within the CNS, retina came up early and often, because it’s a simpler, more accessible structure than the brain,” says Dr. Klassen. “I focused on RP because the vision loss is so severe, but the area of degeneration is often well-defined. Given the severity of the condition, there’s a good risk-benefit profile for the patients.”
The success of Matt LaVail, Ph.D., a Foundation-funded scientist from the University of California, San Francisco, inspired Dr. Klassen to investigate neuroprotection as a treatment approach. “Matt’s work provided a ray of hope for making a difference in RP. Neuroprotection looked promising based on his rodent studies,” he says.
Dr. Klassen and his team received $21 million in funding from the California Institute for Regenerative Medicine (CIRM) for preclinical research and the early-stage human study of their therapy. CIRM was established by California voters in 2004, when they passed a proposition authorizing $3 billion for stem-cell research and therapy development in California.
You can learn more about Dr. Klassen and his research by visiting Eye on the Cure, the Foundation’s blog.