Why Blindness Will Be the First Disorder Cured by Futuristic Treatments
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."
Stronger psychedelics that rewire the brain, with Doug Drysdale
A promising development in science in recent years has been the use technology to optimize something natural. One-upping nature's wisdom isn't easy. In many cases, we haven't - and maybe we can't - figure it out. But today's episode features a fascinating example: using tech to optimize psychedelic mushrooms.
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These mushrooms have been used for religious, spiritual and medicinal purposes for thousands of years, but only in the past several decades have scientists brought psychedelics into the lab to enhance them and maximize their therapeutic value.
Today’s podcast guest, Doug Drysdale, is doing important work to lead this effort. Drysdale is the CEO of a company called Cybin that has figured out how to make psilocybin more potent, so it can be administered in smaller doses without side effects.
The natural form of psilocybin has been studied increasingly in the realm of mental health. Taking doses of these mushrooms appears to help people with anxiety and depression by spurring the development of connections in the brain, an example of neuroplasticity. The process basically shifts the adult brain from being fairly rigid like dried clay into a malleable substance like warm wax - the state of change that's constantly underway in the developing brains of children.
Neuroplasticity in adults seems to unlock some of our default ways of of thinking, the habitual thought patterns that’ve been associated with various mental health problems. Some promising research suggests that psilocybin causes a reset of sorts. It makes way for new, healthier thought patterns.
So what is Drysdale’s secret weapon to bring even more therapeutic value to psilocybin? It’s a process called deuteration. It focuses on the hydrogen atoms in psilocybin. These atoms are very light and don’t stick very well to carbon, which is another atom in psilocybin. As a result, our bodies can easily breaks down the bonds between the hydrogen and carbon atoms. For many people, that means psilocybin gets cleared from the body too quickly, before it can have a therapeutic benefit.
In deuteration, scientists do something simple but ingenious: they replace the hydrogen atoms with a molecule called deuterium. It’s twice as heavy as hydrogen and forms tighter bonds with the carbon. Because these pairs are so rock-steady, they slow down the rate at which psilocybin is metabolized, so it has more sustained effects on our brains.
Cybin isn’t Drysdale’s first go around at this - far from it. He has over 30 years of experience in the healthcare sector. During this time he’s raised around $4 billion of both public and private capital, and has been named Ernst and Young Entrepreneur of the Year. Before Cybin, he was the founding CEO of a pharmaceutical company called Alvogen, leading it from inception to around $500 million in revenues, across 35 countries. Drysdale has also been the head of mergers and acquisitions at Actavis Group, leading 15 corporate acquisitions across three continents.
In this episode, Drysdale walks us through the promising research of his current company, Cybin, and the different therapies he’s developing for anxiety and depression based not just on psilocybin but another psychedelic compound found in plants called DMT. He explains how they seem to have such powerful effects on the brain, as well as the potential for psychedelics to eventually support other use cases, including helping us strive toward higher levels of well-being. He goes on to discuss his views on mindfulness and lifestyle factors - such as optimal nutrition - that could help bring out hte best in psychedelics.
Show links:
Doug Drysdale full bio
Doug Drysdale twitter
Cybin website
Cybin development pipeline
Cybin's promising phase 2 research on depression
Johns Hopkins psychedelics research and psilocybin research
Mets owner Steve Cohen invests in psychedelic therapies
Doug Drysdale, CEO of Cybin
How the body's immune resilience affects our health and lifespan
Story by Big Think
It is a mystery why humans manifest vast differences in lifespan, health, and susceptibility to infectious diseases. However, a team of international scientists has revealed that the capacity to resist or recover from infections and inflammation (a trait they call “immune resilience”) is one of the major contributors to these differences.
Immune resilience involves controlling inflammation and preserving or rapidly restoring immune activity at any age, explained Weijing He, a study co-author. He and his colleagues discovered that people with the highest level of immune resilience were more likely to live longer, resist infection and recurrence of skin cancer, and survive COVID and sepsis.
Measuring immune resilience
The researchers measured immune resilience in two ways. The first is based on the relative quantities of two types of immune cells, CD4+ T cells and CD8+ T cells. CD4+ T cells coordinate the immune system’s response to pathogens and are often used to measure immune health (with higher levels typically suggesting a stronger immune system). However, in 2021, the researchers found that a low level of CD8+ T cells (which are responsible for killing damaged or infected cells) is also an important indicator of immune health. In fact, patients with high levels of CD4+ T cells and low levels of CD8+ T cells during SARS-CoV-2 and HIV infection were the least likely to develop severe COVID and AIDS.
Individuals with optimal levels of immune resilience were more likely to live longer.
In the same 2021 study, the researchers identified a second measure of immune resilience that involves two gene expression signatures correlated with an infected person’s risk of death. One of the signatures was linked to a higher risk of death; it includes genes related to inflammation — an essential process for jumpstarting the immune system but one that can cause considerable damage if left unbridled. The other signature was linked to a greater chance of survival; it includes genes related to keeping inflammation in check. These genes help the immune system mount a balanced immune response during infection and taper down the response after the threat is gone. The researchers found that participants who expressed the optimal combination of genes lived longer.
Immune resilience and longevity
The researchers assessed levels of immune resilience in nearly 50,000 participants of different ages and with various types of challenges to their immune systems, including acute infections, chronic diseases, and cancers. Their evaluation demonstrated that individuals with optimal levels of immune resilience were more likely to live longer, resist HIV and influenza infections, resist recurrence of skin cancer after kidney transplant, survive COVID infection, and survive sepsis.
However, a person’s immune resilience fluctuates all the time. Study participants who had optimal immune resilience before common symptomatic viral infections like a cold or the flu experienced a shift in their gene expression to poor immune resilience within 48 hours of symptom onset. As these people recovered from their infection, many gradually returned to the more favorable gene expression levels they had before. However, nearly 30% who once had optimal immune resilience did not fully regain that survival-associated profile by the end of the cold and flu season, even though they had recovered from their illness.
Intriguingly, some people who are 90+ years old still have optimal immune resilience, suggesting that these individuals’ immune systems have an exceptional capacity to control inflammation and rapidly restore proper immune balance.
This could suggest that the recovery phase varies among people and diseases. For example, young female sex workers who had many clients and did not use condoms — and thus were repeatedly exposed to sexually transmitted pathogens — had very low immune resilience. However, most of the sex workers who began reducing their exposure to sexually transmitted pathogens by using condoms and decreasing their number of sex partners experienced an improvement in immune resilience over the next 10 years.
Immune resilience and aging
The researchers found that the proportion of people with optimal immune resilience tended to be highest among the young and lowest among the elderly. The researchers suggest that, as people age, they are exposed to increasingly more health conditions (acute infections, chronic diseases, cancers, etc.) which challenge their immune systems to undergo a “respond-and-recover” cycle. During the response phase, CD8+ T cells and inflammatory gene expression increase, and during the recovery phase, they go back down.
However, over a lifetime of repeated challenges, the immune system is slower to recover, altering a person’s immune resilience. Intriguingly, some people who are 90+ years old still have optimal immune resilience, suggesting that these individuals’ immune systems have an exceptional capacity to control inflammation and rapidly restore proper immune balance despite the many respond-and-recover cycles that their immune systems have faced.
Public health ramifications could be significant. Immune cell and gene expression profile assessments are relatively simple to conduct, and being able to determine a person’s immune resilience can help identify whether someone is at greater risk for developing diseases, how they will respond to treatment, and whether, as well as to what extent, they will recover.