Researchers Are Testing a New Stem Cell Therapy in the Hopes of Saving Millions from Blindness

Researchers Are Testing a New Stem Cell Therapy in the Hopes of Saving Millions from Blindness

NIH researchers in Kapil Bharti's lab work toward the development of induced pluripotent stem cells to treat dry age-related macular degeneration.

(Screenshot from video: rb.gy/oz2idg)



Of all the infirmities of old age, failing sight is among the cruelest. It can mean the end not only of independence, but of a whole spectrum of joys—from gazing at a sunset or a grandchild's face to reading a novel or watching TV.

The Phase 1 trial will likely run through 2022, followed by a larger Phase 2 trial that could last another two or three years.

The leading cause of vision loss in people over 55 is age-related macular degeneration, or AMD, which afflicts an estimated 11 million Americans. As photoreceptors in the macula (the central part of the retina) die off, patients experience increasingly severe blurring, dimming, distortions, and blank spots in one or both eyes.

The disorder comes in two varieties, "wet" and "dry," both driven by a complex interaction of genetic, environmental, and lifestyle factors. It begins when deposits of cellular debris accumulate beneath the retinal pigment epithelium (RPE)—a layer of cells that nourish and remove waste products from the photoreceptors above them. In wet AMD, this process triggers the growth of abnormal, leaky blood vessels that damage the photoreceptors. In dry AMD, which accounts for 80 to 90 percent of cases, RPE cells atrophy, causing photoreceptors to wither away. Wet AMD can be controlled in about a quarter of patients, usually by injections of medication into the eye. For dry AMD, no effective remedy exists.

Stem Cells: Promise and Perils

Over the past decade, stem cell therapy has been widely touted as a potential treatment for AMD. The idea is to augment a patient's ailing RPE cells with healthy ones grown in the lab. A few small clinical trials have shown promising results. In a study published in 2018, for example, a University of Southern California team cultivated RPE tissue from embryonic stem cells on a plastic matrix and transplanted it into the retinas of four patients with advanced dry AMD. Because the trial was designed to test safety rather than efficacy, lead researcher Amir Kashani told a reporter, "we didn't expect that replacing RPE cells would return a significant amount of vision." Yet acuity improved substantially in one recipient, and the others regained their lost ability to focus on an object.

Therapies based on embryonic stem cells, however, have two serious drawbacks: Using fetal cell lines raises ethical issues, and such treatments require the patient to take immunosuppressant drugs (which can cause health problems of their own) to prevent rejection. That's why some experts favor a different approach—one based on induced pluripotent stem cells (iPSCs). Such cells, first produced in 2006, are made by returning adult cells to an undifferentiated state, and then using chemicals to reprogram them as desired. Treatments grown from a patient's own tissues could sidestep both hurdles associated with embryonic cells.

At least hypothetically. Today, the only stem cell therapies approved by the U.S. Food and Drug Administration (FDA) are umbilical cord-derived products for various blood and immune disorders. Although scientists are probing the use of embryonic stem cells or iPSCs for conditions ranging from diabetes to Parkinson's disease, such applications remain experimental—or fraudulent, as a growing number of patients treated at unlicensed "stem cell clinics" have painfully learned. (Some have gone blind after receiving bogus AMD therapies at those facilities.)

Last December, researchers at the National Eye Institute in Bethesda, Maryland, began enrolling patients with dry AMD in the country's first clinical trial using tissue grown from the patients' own stem cells. Led by biologist Kapil Bharti, the team intends to implant custom-made RPE cells in 12 recipients. If the effort pans out, it could someday save the sight of countless oldsters.

That, however, is what's technically referred to as a very big "if."

The First Steps

Bharti's trial is not the first in the world to use patient-derived iPSCs to treat age-related macular degeneration. In 2013, Japanese researchers implanted such cells into the eyes of a 77-year-old woman with wet AMD; after a year, her vision had stabilized, and she no longer needed injections to keep abnormal blood vessels from forming. A second patient was scheduled for surgery—but the procedure was canceled after the lab-grown RPE cells showed signs of worrisome mutations. That incident illustrates one potential problem with using stem cells: Under some circumstances, the cells or the tissue they form could turn cancerous.

"The knowledge and expertise we're gaining can be applied to many other iPSC-based therapies."

Bharti and his colleagues have gone to great lengths to avoid such outcomes. "Our process is significantly different," he told me in a phone interview. His team begins with patients' blood stem cells, which appear to be more genomically stable than the skin cells that the Japanese group used. After converting the blood cells to RPE stem cells, his team cultures them in a single layer on a biodegradable scaffold, which helps them grow in an orderly manner. "We think this material gives us a big advantage," Bharti says. The team uses a machine-learning algorithm to identify optimal cell structure and ensure quality control.

It takes about six months for a patch of iPSCs to become viable RPE cells. When they're ready, a surgeon uses a specially-designed tool to insert the tiny structure into the retina. Within days, the scaffold melts away, enabling the transplanted RPE cells to integrate fully into their new environment. Bharti's team initially tested their method on rats and pigs with eye damage mimicking AMD. The study, published in January 2019 in Science Translational Medicine, found that at ten weeks, the implanted RPE cells continued to function normally and protected neighboring photoreceptors from further deterioration. No trace of mutagenesis appeared.

Encouraged by these results, Bharti began recruiting human subjects. The Phase 1 trial will likely run through 2022, followed by a larger Phase 2 trial that could last another two or three years. FDA approval would require an even larger Phase 3 trial, with a decision expected sometime between 2025 and 2028—that is, if nothing untoward happens before then. One unknown (among many) is whether implanted cells can thrive indefinitely under the biochemically hostile conditions of an eye with AMD.

"Most people don't have a sense of just how long it takes to get something like this to work, and how many failures—even disasters—there are along the way," says Marco Zarbin, professor and chair of Ophthalmology and visual science at Rutgers New Jersey Medical School and co-editor of the book Cell-Based Therapy for Degenerative Retinal Diseases. "The first kidney transplant was done in 1933. But the first successful kidney transplant was in 1954. That gives you a sense of the time frame. We're really taking the very first steps in this direction."

Looking Ahead

Even if Bharti's method proves safe and effective, there's the question of its practicality. "My sense is that using induced pluripotent stem cells to treat the patient from whom they're derived is a very expensive undertaking," Zarbin observes. "So you'd have to have a very dramatic clinical benefit to justify that cost."

Bharti concedes that the price of iPSC therapy is likely to be high, given that each "dose" is formulated for a single individual, requires months to manufacture, and must be administered via microsurgery. Still, he expects economies of scale and production to emerge with time. "We're working on automating several steps of the process," he explains. "When that kicks in, a technician will be able to make products for 10 or 20 people at once, so the cost will drop proportionately."

Meanwhile, other researchers are pressing ahead with therapies for AMD using embryonic stem cells, which could be mass-produced to treat any patient who needs them. But should that approach eventually win FDA approval, Bharti believes there will still be room for a technique that requires neither fetal cell lines nor immunosuppression.

And not only for eye ailments. "The knowledge and expertise we're gaining can be applied to many other iPSC-based therapies," says the scientist, who is currently consulting with several companies that are developing such treatments. "I'm hopeful that we can leverage these approaches for a wide range of applications, whether it's for vision or across the body."

NEI launches iPS cell therapy trial for dry AMD

Kenneth Miller
Kenneth Miller is a freelance writer based in Los Angeles. He is a contributing editor at Discover, and has reported from four continents for publications including Time, Life, Rolling Stone, Mother Jones, and Aeon. His honors include The ASJA Award for Best Science Writing and the June Roth Memorial Award for Medical Writing. Visit his website at www.kennethmiller.net.
Study Shows “Living Drug” Can Provide a Lasting Cure for Cancer

A recent study by researchers at the University of Pennsylvania examined how CAR-T therapy helped Doug Olson beat a cancer death sentence for over a decade - and how it could work for more people.

Penn Medicine

Doug Olson was 49 when he was diagnosed with chronic lymphocytic leukemia, a blood cancer that strikes 21,000 Americans annually. Although the disease kills most patients within a decade, Olson’s case progressed more slowly, and courses of mild chemotherapy kept him healthy for 13 years. Then, when he was 62, the medication stopped working. The cancer had mutated, his doctor explained, becoming resistant to standard remedies. Harsher forms of chemo might buy him a few months, but their side effects would be debilitating. It was time to consider the treatment of last resort: a bone-marrow transplant.

Olson, a scientist who developed blood-testing instruments, knew the odds. There was only a 50 percent chance that a transplant would cure him. There was a 20 percent chance that the agonizing procedure—which involves destroying the patient’s marrow with chemo and radiation, then infusing his blood with donated stem cells—would kill him. If he survived, he would face the danger of graft-versus-host disease, in which the donor’s cells attack the recipient’s tissues. To prevent it, he would have to take immunosuppressant drugs, increasing the risk of infections. He could end up with pneumonia if one of his three grandchildren caught a sniffle. “I was being pushed into a corner,” Olson recalls, “with very little room to move.”

Keep Reading Keep Reading
Kenneth Miller
Kenneth Miller is a freelance writer based in Los Angeles. He is a contributing editor at Discover, and has reported from four continents for publications including Time, Life, Rolling Stone, Mother Jones, and Aeon. His honors include The ASJA Award for Best Science Writing and the June Roth Memorial Award for Medical Writing. Visit his website at www.kennethmiller.net.
A Stomach Implant Saved Me. When Your Organs Fail, You Could Become a Cyborg, Too

Ordinary people are living better with chronic conditions thanks to a recent explosion of developments in medical implants.

Adobe Stock

Beware, cyborgs walk among us. They’re mostly indistinguishable from regular humans and are infiltrating every nook and cranny of society. For full disclosure, I’m one myself. No, we’re not deadly intergalactic conquerors like the Borg race of Star Trek fame, just ordinary people living better with chronic conditions thanks to medical implants.

In recent years there has been an explosion of developments in implantable devices that merge multiple technologies into gadgets that work in concert with human physiology for the treatment of serious diseases. Pacemakers for the heart are the best-known implants, as well as other cardiac devices like LVADs (left-ventricular assist devices) and implanted defibrillators. Next-generation devices address an array of organ failures, and many are intended as permanent. The driving need behind this technology: a critical, persistent shortage of implantable biological organs.

Keep Reading Keep Reading
Eve Herold
Eve Herold is an award-winning science writer and consultant in the scientific and medical nonprofit space. A longtime communications and policy executive for scientific organizations, she currently serves as Director of Policy Research and Education for the Healthspan Action Coalition. She has written extensively about issues at the crossroads of science and society, including regenerative medicine, aging and longevity, medical implants, transhumanism, robotics and AI, and bioethical issues in leading-edge medicine. Her books include Stem Cell Wars and Beyond Human, and her latest book, Robots and the People Who Love Them, will be released in January 2024. Her work has appeared in Vice, Medium, The Washington Post and the Boston Globe, among others. She’s a frequent contributor to Leaps.org and is the recipient of the 2019 Arlene Eisenberg Award from the American Society of Journalists and Authors.