Why Blindness Will Be the First Disorder Cured by Futuristic Treatments
A blind man with a cane goes for a walk at sunset. (© Prazis/Fotolia)
Stem cells and gene therapy were supposed to revolutionize biomedicine around the turn of the millennium and provide relief for desperate patients with incurable diseases. But for many, progress has been frustratingly slow. We still cannot, for example, regenerate damaged organs like a salamander regrows its tail, and genome engineering is more complicated than cutting and pasting letters in a word document.
"There are a number of things that make [the eye] ideal for new experimental therapies which are not true necessarily in other organs."
For blind people, however, the future of medicine is one step closer to reality. In December, the FDA approved the first gene therapy for an inherited disease—a mutation in the gene RPE65 that causes a rare form of blindness. Several clinical trials also show promise for treating various forms of retinal degeneration using stem cells.
"It's not surprising that the first gene therapy that was approved by the FDA was a therapy in the eye," says Bruce Conklin, a senior investigator at the San Francisco-based Gladstone Institutes, a nonprofit life science research organization, and a professor in the Medical Genetics and Molecular Pharmacology department at the University of California, San Francisco. "There are a number of things that make it ideal for new experimental therapies which are not true necessarily in other organs."
Physicians can easily see into the eye to check if a procedure worked or if it's causing problems. "The imaging technology within the eye is really unprecedented. You can't do this in someone's spinal cord or someone's brain cells or immune system," says Conklin, who is also deputy director of the Innovative Genomics Institute.
There's also a built-in control: researchers can test an intervention on one eye first. What's more, if something goes wrong, the risk of mortality is low, especially when compared to experimenting on the heart or brain. Most types of blindness are currently incurable, so the risk-to-reward ratio for patients is high. If a problem arises with the treatment their eyesight could get worse, but if they do nothing their vision will likely decline anyway. And if the treatment works, they may be able to see for the first time in years.
Gene Therapy
An additional appeal for testing gene therapy in the eye is the low risk for off-target effects, in which genome edits could result in unintended changes to other genes or in other cell types. There are a number of genes that are solely expressed in the eye and not in any other part of the body. Manipulating those genes will only affect cells in the eye, so concerns about the impact on other organs are minimal.
Ninety-three percent of patients who received the injection had improved vision just one month after treatment.
RPE65 is one such gene. It creates an enzyme that helps the eye convert light into an electrical signal that travels back to the brain. Patients with the mutation don't produce the enzyme, so visual signals are not processed. However, the retinal cells in the eye remain healthy for years; if you can restore the missing enzyme you can restore vision.
The newly approved therapy, developed by Spark Therapeutics, uses a modified virus to deliver RPE65 into the eye. A retinal surgeon injects the virus, which has been specially engineered to remove its disease-causing genes and instead carry the correct RPE65 gene, into the retina. There, it is sucked up by retinal pigment epithelial (RPE) cells. The RPE cells are a particularly good target for injection because their job is to eat up and recycle rogue particles. Once inside the cell, the virus slips into the nucleus and releases the DNA. The RPE65 gene then goes to work, using the cell's normal machinery to produce the needed enzyme.
In the most recent clinical trial, 93 percent of patients who received the injection—who range in age from 4 to 44—had improved vision just one month after treatment. So far, the benefits have lasted at least two years.
"It's an exciting time for this class of diseases, where these people have really not had treatments," says Spark president and co-founder, Katherine High. "[Gene therapy] affords the possibility of treatment for diseases that heretofore other classes of therapeutics really have not been able to help."
Stem Cells
Another benefit of the eye is its immune privilege. In order to let light in, the eye must remain transparent. As a result, its immune system is dampened so that it won't become inflamed if outside particles get in. This means the eye is much less likely to reject cell transplants, so patients do not need to take immunosuppressant drugs.
One study generating buzz is a clinical trial in Japan that is the first and, so far, only test of induced pluripotent stem cells in the eye.
Henry Klassen, an assistant professor at UC Irvine, is taking advantage of the eye's immune privilege to transplant retinal progenitor cells into the eye to treat retinitis pigmentosa, an inherited disease affecting about 1 in 4000 people that eventually causes the retina to degenerate. The disease can stem from dozens of different genetic mutations, but the result is the same: RPE cells die off over the course of a few decades, leaving the patient blind by middle age. It is currently incurable.
Retinal progenitor cells are baby retinal cells that develop naturally from stem cells and will turn into one of several types of adult retinal cells. When transplanted into a patient's eye, the progenitor cells don't replace the lost retinal cells, but they do secrete proteins and enzymes essential for eye health.
"At the stage we get the retinal tissue it's immature," says Klassen. "They still have some flexibility in terms of which mature cells they can turn into. It's that inherent flexibility that gives them a lot of power when they're put in the context of a diseased retina."
Klassen's spin-off company, jCyte, sponsored the clinical trial with support from the California Institute for Regenerative Medicine. The results from the initial study haven't been published yet, but Klassen says he considers it a success. JCyte is now embarking on a phase two trial to assess improvements in vision after the treatment, which will wrap up in 2021.
Another study generating buzz is a clinical trial in Japan that is the first and, so far, only test of induced pluripotent stem cells (iPSC) in the eye. iPSC are created by reprogramming a patient's own skin cells into stem cells, circumventing any controversy around embryonic stem cell sources. In the trial, led by Masayo Takahashi at RIKEN, the scientists transplant retinal pigment epithelial cells created from iPSC into the retinas of patients with age-related macular degeneration. The first woman to receive the treatment is doing well, and her vision is stable. However, the second patient suffered a swollen retina as a result of the surgery. Despite this recent setback, Takahashi said last week that the trial would continue.
Botched Jobs
Although recent studies have provided patients with renewed hope, the field has not been without mishap. Most notably, an article in the New England Journal of Medicine last March described three patients who experienced severe side effects after receiving stem cell injections from a Florida clinic to treat age-related macular degeneration. Following the initial article, other reports came out about similar botched treatments. Lawsuits have been filed against US Stem Cell, the clinic that conducted the procedure, and the FDA sent them a warning letter with a long list of infractions.
"One red flag is that the clinics charge patients to take part in the treatment—something extremely unusual for legitimate clinical trials."
Ajay Kuriyan, an ophthalmologist and retinal specialist at the University of Rochester who wrote the paper, says that because details about the Florida trial are scarce, it's hard to say why the treatment caused the adverse reaction. His guess is that the stem cells were poorly prepared and not up to clinical standards.
Klassen agrees that small clinics like US Stem Cell do not offer the same caliber of therapy as larger clinical trials. "It's not the same cells and it's not the same technique and it's not the same supervision and it's not under FDA auspices. It's just not the same thing," he says. "Unfortunately, to the patient it might sound the same, and that's the tragedy for me."
For patients who are interested in joining a trial, Kuriyan listed a few things to watch out for. "One red flag is that the clinics charge patients to take part in the treatment—something extremely unusual for legitimate clinical trials," he says. "Another big red flag is doing the procedure in both eyes" at the same time. Third, if the only treatment offered is cell therapy. "These clinics tend to be sort of stand-alone clinics, and that's not very common for an actual big research study of this scale."
Despite the recent scandal, Klassen hopes that the success of his trial and others will continue to push the field forward. "It just takes so many decades to move this stuff along, even when you're trying to simplify it as much as possible," he says. "With all the heavy lifting that's been done, I hope the world's got the patience to get this through."
Here's how one doctor overcame extraordinary odds to help create the birth control pill
Dr. Percy Julian had so many personal and professional obstacles throughout his life, it’s amazing he was able to accomplish anything at all. But this hidden figure not only overcame these incredible obstacles, he also laid the foundation for the creation of the birth control pill.
Julian’s first obstacle was growing up in the Jim Crow-era south in the early part of the twentieth century, where racial segregation kept many African-Americans out of schools, libraries, parks, restaurants, and more. Despite limited opportunities and education, Julian was accepted to DePauw University in Indiana, where he majored in chemistry. But in college, Julian encountered another obstacle: he wasn’t allowed to stay in DePauw’s student housing because of segregation. Julian found lodging in an off-campus boarding house that refused to serve him meals. To pay for his room, board, and food, Julian waited tables and fired furnaces while he studied chemistry full-time. Incredibly, he graduated in 1920 as valedictorian of his class.
After graduation, Julian landed a fellowship at Harvard University to study chemistry—but here, Julian ran into yet another obstacle. Harvard thought that white students would resent being taught by Julian, an African-American man, so they withdrew his teaching assistantship. Julian instead decided to complete his PhD at the University of Vienna in Austria. When he did, he became one of the first African Americans to ever receive a PhD in chemistry.
Julian received offers for professorships, fellowships, and jobs throughout the 1930s, due to his impressive qualifications—but these offers were almost always revoked when schools or potential employers found out Julian was black. In one instance, Julian was offered a job at the Institute of Paper Chemistory in Appleton, Wisconsin—but Appleton, like many cities in the United States at the time, was known as a “sundown town,” which meant that black people weren’t allowed to be there after dark. As a result, Julian lost the job.
During this time, Julian became an expert at synthesis, which is the process of turning one substance into another through a series of planned chemical reactions. Julian synthesized a plant compound called physostigmine, which would later become a treatment for an eye disease called glaucoma.
In 1936, Julian was finally able to land—and keep—a job at Glidden, and there he found a way to extract soybean protein. This was used to produce a fire-retardant foam used in fire extinguishers to smother oil and gasoline fires aboard ships and aircraft carriers, and it ended up saving the lives of thousands of soldiers during World War II.
At Glidden, Julian found a way to synthesize human sex hormones such as progesterone, estrogen, and testosterone, from plants. This was a hugely profitable discovery for his company—but it also meant that clinicians now had huge quantities of these hormones, making hormone therapy cheaper and easier to come by. His work also laid the foundation for the creation of hormonal birth control: Without the ability to synthesize these hormones, hormonal birth control would not exist.
Julian left Glidden in the 1950s and formed his own company, called Julian Laboratories, outside of Chicago, where he manufactured steroids and conducted his own research. The company turned profitable within a year, but even so Julian’s obstacles weren’t over. In 1950 and 1951, Julian’s home was firebombed and attacked with dynamite, with his family inside. Julian often had to sit out on the front porch of his home with a shotgun to protect his family from violence.
But despite years of racism and violence, Julian’s story has a happy ending. Julian’s family was eventually welcomed into the neighborhood and protected from future attacks (Julian’s daughter lives there to this day). Julian then became one of the country’s first black millionaires when he sold his company in the 1960s.
When Julian passed away at the age of 76, he had more than 130 chemical patents to his name and left behind a body of work that benefits people to this day.
Therapies for Healthy Aging with Dr. Alexandra Bause
My guest today is Dr. Alexandra Bause, a biologist who has dedicated her career to advancing health, medicine and healthier human lifespans. Dr. Bause co-founded a company called Apollo Health Ventures in 2017. Currently a venture partner at Apollo, she's immersed in the discoveries underway in Apollo’s Venture Lab while the company focuses on assembling a team of investors to support progress. Dr. Bause and Apollo Health Ventures say that biotech is at “an inflection point” and is set to become a driver of important change and economic value.
Previously, Dr. Bause worked at the Boston Consulting Group in its healthcare practice specializing in biopharma strategy, among other priorities
She did her PhD studies at Harvard Medical School focusing on molecular mechanisms that contribute to cellular aging, and she’s also a trained pharmacist
In the episode, we talk about the present and future of therapeutics that could increase people’s spans of health, the benefits of certain lifestyle practice, the best use of electronic wearables for these purposes, and much more.
Dr. Bause is at the forefront of developing interventions that target the aging process with the aim of ensuring that all of us can have healthier, more productive lifespans.
