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.
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
From Crap to Cure: The Story of Fecal Transplants
Meg Newman, who suffered from C. difficile, underwent a fecal transplant that helped restore her to health.
C. difficile had Meg Newman's number; it had struck her 18 different times beginning in 1985. The bacterial infection takes over the gut bringing explosive diarrhea, dehydration, weight loss, and at its worst depletes blood platelets. It causes nearly 30,000 deaths each year in the U.S. alone.
"I was one sick puppy as that point and literally three days after the transplant I was doing pretty well, day four even better."
Meg knew these statistics not just from personal experience but also because she was a doctor at San Francisco General Hospital. Antibiotics had sometimes helped to treat the infection, but it never quite seemed to go away. Now, "It felt like part of my colon was sort of sliding off as I had the bowel movement." On her worst day she counted 33 bowel movements. It was 2005 and she knew she was at the end of her rope.
Medical training had taught Meg to look at the data. So when antibiotics failed, she searched the literature for other options. One was a seemingly off-the-wall treatment called fecal transplants, which essentially gives poop from a healthy person to one who is sick.
Its roots stretch back to "yellow soup" used to treat dysentery in China nearly two thousand years ago, in which ancient Chinese treaters would combine stool with liquid, mash it up, and administer it. The approach also is commonly used in veterinary medicine today. However, there were only about three papers on its use in humans in the medical literature at that time, she recalls. Still, the logic of the intervention appealed to her.
The gut microbiome as a concept and even a word were not widely known fifteen years ago. But the idea that the microbial community in her gut was in disarray, and a transplant of organisms from a healthy gut might help restore a more normal ecology made sense. And besides, the failure of standard medicine left her few options.
Meg spoke with a colleague, gastroenterologist Neil Stollman, about a possible fecal microbial transplant (FMT). Only a handful of doctors in the U.S. had ever done the procedure; Stollman had tried it just once before. After conversation with Newman, he agreed to do it.
They decided on Meg's partner Sherry as the donor. "I try very hard to use intimate sexual partners as the donor," explains Stollman. The reason is to reduce disease risk: "The logic there is pretty straightforward. If you have unprotected sex with this individual, in a monogamous way for a period of time, you have assumed pretty much any infectious risk," like hepatitis, HIV, and syphilis, he says. Other donors would be screened using the same criteria used to screen blood donations, plus screening for parasites that can live in stool but not blood.
The procedure
Martini aficionados fall into two camps, fans of shaken or stirred. In the early days the options for producing of fecal transplants were a blender or hand shaken. Stollman took the hands-on approach, mixing Sherry's fecal donation with saline to create "a milkshake in essence." He filtered it several times through gauze to get out the lumps.
Then he inserted a colonoscope, a long flexible tube, through the anus into Meg's colon. Generally a camera goes through the tube to look for polyps and cancers, while other tools can snip off polyps and retrieve tissue samples. Today he used it to insert the fecal "milkshake" as high up the colon as he could go. Imodium and bed rest were the final pieces. It works about 90 percent of the time today.
Meg went home with fingers crossed. "And within about two weeks things just slowed down; the diarrhea just stopped. I felt better so my appetite was better." The tide had turned, though it would take months to slowly repair the toll taken on her body from disease and antibiotics.
Then in 2011 another serious medical challenge required heavy use of antibiotics and Meg's C. difficile came roaring back; she needed a second FMT. Sherry had a bad sinus infection and had been on antibiotics, so that ruled her out as a donor. Red, Meg's godson, volunteered. He was twenty-one and had little or no exposure to antibiotics, which can harm friendly bacteria living in the gut.
"I was one sick puppy as that point," Meg recalls, "and literally three days after the transplant [from Red] I was doing pretty well, day four even better. It was unbelievable." It illustrated that donors are not the same, and that while an intimate partner may be the safest option, it also may not be the most efficacious donation in terms of providing missing parts of the microbial ecosystem.
Going mainstream
By then, FMTs were starting to come out of the shadows as more than just a medical oddity. One gigantic milestone in changing perceptions was a Dutch study on using the procedure to treat C. difficile that was published in January 2013 in the New England Journal of Medicine. "That was the first trial where people said, look this isn't voodoo. This wasn't made up; it really worked," says Colleen Kelly, another pioneer in using FMTs to treat C. difficile and a researcher at Brown University. A single dose was successful more than 80 percent of the time in resolving disease in patients who had failed multiple regimens of antibiotics.
Charlatans pounced on the growing interest in the microbiome, promoting FMT as a cure for all sorts of ailments for which there was no scientific evidence. The FDA stepped in, announcing it would regulate the procedure as a drug, and essentially banned use of FMTs until it wrote regulations. But the outcry from physicians and patients was so great it was forced to retreat and has allowed continued use in treating C. difficile albeit on an interim regulatory basis that has continued since 2013.
Another major change was the emergence of stool banks, modeled on blood banks. The most widely know is OpenBiome, established in 2012 as a nonprofit by young researchers at Harvard and MIT. It aimed to standardize donation of stool and screening for disease, and package them in frozen form for colonoscopic delivery, or pill form. It greatly simplified the process and more doctors became willing to use FMTs to treat C. difficile. Today, some gastroenterologists specialize in administering the transplants as a feature of their practice.
To be sure, there have been some setbacks, including a transplant between family members where the recipient became obese, likely in part because of bacteria in the material she received. The same thing has occurred in studies in mice. And last year, an elderly man died from a toxic strain of E. coli that was in material provided by a stool bank. That caused the FDA to add that pathogen to the list of those one must screen for in products designed for use as fecal transplants.
Cost remains an issue. OpenBiome charges $1500-$2000 per transplant dose, depending on whether a frozen or pill form of the product is used. And that is likely to go up as the FDA increases the number of diseases that must be screened for, such as the virus that causes COVID-19, which is present in feces and likely can be transmitted through feces. Most insurance companies do not cover FMTs because no product has been formally approved for use by the FDA.
One of the greatest treatment challenges is making the correct diagnosis, says physician Robin Patel, who initially treated patients at the Mayo Clinic in Rochester, Minnesota but now spends most of her time there developing new diagnostics. Many things can cause diarrhea and the simple presence of the organism does not mean that C. difficile is causing it. In addition, many people are colonized with the bug but never develop symptoms of the disease.
Patel used the expensive tool of whole genome sequencing to look in great detail at C. difficile in patients who were treated with antibiotics for the infection and had recurrent diarrhea. "Some of them, as you might predict, were getting their symptoms with the same exact strain [of C. difficile] but others were not, it was a different strain," suggesting that they had been reinfected.
If it is a different strain, you might want to try antibiotics, she says, but if the same strain is present, then you might want to try a different approach such as FMT. Whole genome sequencing is still too slow and expensive to use in regularly treating patients today, but Patel hopes to develop a rapid, cost-effective test to help doctors make those types of decisions.
Biotech companies are trying to develop alternatives to poop as a source for transplant to treat C. difficile. They are picking and choosing different bacteria that they can grow and then combine into a product, to varying degrees of success, but none have yet crossed the finish line of FDA approval.
"I think [the future of FMTs] is going to be targeted, even custom-made."
The FDA would like such a product because it is used to dealing with small molecule drugs that are standardized and produced in batches. Companies are pursing it because, as Kelly says, they are like sharks "smelling money in the water." Approval of such a product might cause the FDA to shut down existing stool banks that now exist in a regulatory limbo, leaving the company with a monopoly of exclusive rights to the treatment.
Back when Meg received her first fecal transplant, the procedure was so obscure that the guidelines for treating C. difficile put out by the American College of Gastroenterology didn't even mention FMT. The procedure crept into the 2013 revision of those guidelines as a treatment of last resort. Guidance under review for release later this year or early next year will ease use further but stop short of making it a first option.
Stollman imagines a future holy grail in treating C. difficile: "You give me a stool specimen and I run it through a scanner that tells me you have too much of this and too little of that. I have a sense of what normal [microbial composition of the gut] should be and add some of this and subtract some of that. Maybe I even give you some antibiotics to get rid of some of the bad guys, give you some probiotics. I think it is going to be targeted, even custom-made."
His complete vision for treating C. difficile won't arrive tomorrow, but given how rapidly FMTs have become part of medicine, it is likely to arrive in pieces and more quickly than one might think.
About five years ago Meg discovered she had an antibody deficiency that contributed to her health problems, including vulnerability to C. difficile. She began supplementation with immunoglobulin and "that has made a huge difference in my health. It is just unbelievable how much better I am." She is grateful that fecal transplants gave her the time to figure that out. She believes "there's every reason to consider it [FMT] as a first-line treatment and do the studies, ASAP."
“You First”: Who Will Be Front in Line to Get a COVID Vaccine?
A small subset of hospitals and institutions in high-risk areas are likely to go first, according to bioethicist Arthur Caplan.
There is a huge amount riding on the discovery of a vaccine effective against the Covid-19 virus.
Making 660 million of anything without a glitch is—to put it mildly—a tall order in a nation that remains short on masks, gowns, and diagnostic tests despite months of trying to meet demand.
The world is waiting for a vaccine that can liberate everyone from the constraints on liberty required by existing efforts to fight the virus with public health measures such as masks, isolation, and quarantining. President Trump, for the most part, has rejected tough public health measures. Instead he has staked his political future and those of the governors and Congressional Republicans who have followed his lead on delivering a vaccine before Election Day as the solution to the COVID-19 pandemic in the USA. Many scientific experts have been sounding encouraging notes about having a vaccine by the end of this year or early next, as have many CEOs among the more than 160 companies chasing various strategies to identify a safe and effective vaccine.
But the reality is that no matter how fast a vaccine appears, those who might benefit will face a significant period of time before they could receive one. This is due to a variety of realities. Any vaccine faces various regulatory hurdles to insure safety and efficacy. This means completing large-scale studies in tens of thousands of subjects hoping for enough cases of blunted natural infection versus a large placebo control group to determine that a vaccine works. And that takes time--plus adding in delays in manufacturing and delivery, which will create logjams for most prospective recipients.
Shipping is not going to be easy with cold chain storage requirements from -20 to -70 degrees Celsius, from factory to a doctor's office, depending on the vaccine. In addition, many of the vaccines under development require two doses--that is 660 million shots to cover just those in the United States. Making 660 million of anything without a glitch is—to put it mildly—a tall order in a nation that remains short on masks, gowns, and diagnostic tests, despite months of trying to meet demand.
There are three scenarios under which a vaccine can appear but without being in any way available to all Americans.
The first is a vaccine under development in the USA or with some USA financing begins to show promise before a full clinical trial is completed. Current vaccine trials are supervised by Data Safety and Monitoring Boards and those committees could tell a CEO eager to be first to market that their vaccine is looking good at the study's half-way point.
The CEO and vaccine manufacturing company's board then let the White House know that a magic bullet which can ensure the President's reelection is in hand. The President, as he has done many times with other COVID treatments, most recently convalescent plasma, intervenes with the FDA and demands approval using an Emergency Use Authorization, or invoking the Federal Right to Try law he and Mike Pence are constantly touting. FDA Commissioner Steve Hahn folds and an extremely limited supply of vaccine, maybe only 100,000 doses, is available just before Election Day.
The second scenario is that another nation discovers a vaccine that looks safe and effective and the USA is able to buy some supply of it. But again, we are likely, initially, to get an extremely limited amount.
Lastly, the vaccine is approved in a standard manner. A full randomized trial is done, the endpoints are met, and no serious adverse events are identified. It is a USA-funded vaccine so most of it is coming here first. Still the vials and needles and plugs need to be quality-controlled and shipped and stored at the right temperatures. Information sheets and consent forms need to be readied, offered, and signed. Odds are you won't see any of this vaccine until late next year. So, who is going to get the first shots?
Some people under all of these scenarios are going to say, "Count me out." They don't trust vaccines or they don't trust the government to provide a safe one. Others may say, "The first one out of the box may be OK, but I am going to wait for the 'best' one before I take one." Even if those numbers are large, it is still certain that there will be more takers than can be vaccinated.
If you look at the discussion of vaccine rationing, almost everybody — including government officials, FDA officials, advisory panelists and ethicists — says the first group that should get vaccinated are at-risk healthcare workers. They say it, although they're not always clear about why.
One reason is that you need to give it to health care workers first because they will keep the healthcare system going. Another is that you need to give it to them first because they face more risk and they should get rewarded for having done and continuing to do that -- their bravery ought to be rewarded and their risk reduced.
A subset of hospitals and institutions in high risk areas will [go first] and that will be it for a significant period of time.
Both of these arguments for health care worker priority are not completely convincing. Food and power and vaccine manufacturing are arguably as important as health care, but workers in those areas don't get priority attention in most guidelines. And many Americans face risks from COVID comparable to health care workers, especially those who are not on the front lines in ERs and ICUs. Prisoners, military personnel who work on warships, the elderly, nursing home residents, and poor minorities are disproportionately affected by COVID. However, none of them are going first, nor is it clear how to weigh their claims in competing against one another for a scarce vaccine.
But, there's something else that's interesting in deciding who goes first. When people all agree, as they almost always do, that it's health care workers who must go first, a huge problem remains. What is the definition of who's a healthcare worker? You could easily get millions and millions of people designated as healthcare workers who would have a claim to go first.
We normally think that health care worker means doctors and nurses. But, if we go beyond those who work in ERs and ICUs, the number is big. And we must, because no ER or ICU can run without huge numbers of supporting individuals.
If you don't vaccinate lab technicians, people who clean the rooms, make food, transport patients, provide security, do the laundry, run the IT, students, volunteers and so on, you're not going to have a functioning hospital. If you don't include those working in nursing homes, home care and hospices along with those making and supplying vital equipment and bringing in patients via ambulances, police cars, and fire trucks, you don't have a functioning ICU, much less a health care system.
The total number involved could easily exceed tens of millions depending on how broadly the definition is set.
So, what is likely to happen is that health care workers will not go first. A subset of hospitals and institutions in high risk areas will and that will be it for a significant period of time. Health care institutions in hot spots, plus the supporting services they need will go first and then vaccine availability will slowly expand to other health care institutions and the essential workers needed to keep them functioning. Then consideration will also be given to how best to control the spread of the virus in selecting hot spots versus saving prisoners or the poor. And you can be sure, whatever the guidelines are, that the military and security folks will demand their share.
For many, many months if not a year or more, most people will not have to face a choice about vaccinating. The supply just won't be there for the general public. It is a small sample of high-risk health care workers including vaccine manufacturing employees and shippers, plus essential workers to keep hospitals and nursing homes going, who will be first in line. Odds are you and your family will still be wearing masks and social distancing well into next year.