Anti-Aging Pioneer Aubrey de Grey: “People in Middle Age Now Have a Fair Chance”
Kira Peikoff was the editor-in-chief of Leaps.org from 2017 to 2021. As a journalist, her work has appeared in The New York Times, Newsweek, Nautilus, Popular Mechanics, The New York Academy of Sciences, and other outlets. She is also the author of four suspense novels that explore controversial issues arising from scientific innovation: Living Proof, No Time to Die, Die Again Tomorrow, and Mother Knows Best. Peikoff holds a B.A. in Journalism from New York University and an M.S. in Bioethics from Columbia University. She lives in New Jersey with her husband and two young sons. Follow her on Twitter @KiraPeikoff.
Aging is not a mystery, says famed researcher Dr. Aubrey de Grey, perhaps the world's foremost advocate of the provocative view that medical technology will one day allow humans to control the aging process and live healthily into our hundreds—or even thousands.
"The cultural attitudes toward all of this are going to be completely turned upside down by sufficiently promising results in the lab, in mice."
He likens aging to a car wearing down over time; as the body operates normally, it accumulates damage which can be tolerated for a while, but eventually sends us into steep decline. The most promising way to escape this biological reality, he says, is to repair the damage as needed with precise scientific tools.
The bad news is that doing this groundbreaking research takes a long time and a lot of money, which has not always been readily available, in part due to a cultural phenomenon he terms "the pro-aging trance." Cultural attitudes have long been fatalistic about the inevitability of aging; many people balk at the seemingly implausible prospect of indefinite longevity.
But the good news for de Grey—and those who are cheering him on—is that his view is becoming less radical these days. Both the academic and private sectors are racing to tackle aging; his own SENS Research Foundation, for one, has spun out into five different companies. Defeating aging, he says, "is not just a future industry; it's an industry now that will be both profitable and extremely good for your health."
De Grey sat down with Editor-in-Chief Kira Peikoff at the World Stem Cell Summit in Miami to give LeapsMag the latest scoop on his work. Here is an edited and condensed version of our conversation.
Since your book Ending Aging was published a decade ago, scientific breakthroughs in stem cell research, genome editing, and other fields have taken the world by storm. Which of these have most affected your research?
They have all affected it a lot in one way, and hardly at all in another way. They have speeded it up--facilitated short cuts, ways to get where we're already trying to go. What they have not done is identified any fundamental changes to the overall strategy. In the book, we described the seven major types of damage, and particular ways of going about fixing each of them, and that hasn't changed.
"Repair at the microscopic level, one would be able to expect to do without surgery, just by injecting the right kind of stem cells."
Has any breakthrough specifically made the biggest impact?
It's not just the obvious things, like iPS (induced pluripotent stem cells) and CRISPR (a precise tool for editing genes). It's also the more esoteric things that applied specifically to certain of our areas, but most people don't really know about them. For example, the identification of how to control something called co-translational mitochondrial protein import.
How much of the future of anti-aging treatments will involve regeneration of old tissue, or wholesale growth of new organs?
The more large-scale ones, regenerating whole new organs, are probably only going to play a role in the short-term and will be phased out relatively rapidly, simply because, in order to be useful, one has to employ surgery, which is really invasive. We'll want to try to get around that, but it seems quite likely that in the very early stages, the techniques we have for repairing things at the molecular and cellular level in situ will be insufficiently comprehensive, and so we will need to do the more sledgehammer approach of building a whole new organ and sticking it in.
Every time you are in a position where you're replacing an organ, you have the option, in principle, of repairing the organ, without replacing it. And repair at the microscopic level, one would be able to expect to do without surgery, just by injecting the right kind of stem cells or whatever. That would be something one would expect to be able to apply to someone much closer to death's door and much more safely in general, and probably much more cheaply. One would expect that subsequent generations of these therapies would move in that direction.
Your foundation is working on an initiative requiring $50 million in funding—
Well, if we had $50 million per year in funding, we could go about three times faster than we are on $5 million per year.
And you're looking at a 2021 timeframe to start human trials?
That's approximate. Remember, because we accumulate in the body so many different types of damage, that means we have many different types of therapy to repair that damage. And of course, each of those types has to be developed independently. It's very much a divide and conquer therapy. The therapies interact with each other to some extent; the repair of one type of damage may slow down the creation of another type of damage, but still that's how it's going to be.
And some of these therapies are much easier to implement than others. The easier components of what we need to do are already in clinical trials—stem cell therapies especially, and immunotherapy against amyloid in the brain, for example. Even in phase III clinical trials in some cases. So when I talk about a timeframe like 2021, or early 20s shall we say, I'm really talking about the most difficult components.
What recent strides are you most excited about?
Looking back over the past couple of years, I'm particularly proud of the successes we've had in the very most difficult areas. If you go through the 7 components of SENS, there are two that have absolutely been stuck in a rut and have gotten nowhere for 15 to 20 years, and we basically fixed that in both cases. We published two years ago in Science magazine that essentially showed a way forward against the stiffening of the extracellular matrix, which is responsible for things like wrinkles and hypertension. And then a year ago, we published a real breakthrough paper with regard to placing copies of the mitochondria DNA in the nuclear DNA modified in such a way that they still work, which is an idea that had been around for 30 years; everyone had given up on it, some a long time ago, and we basically revived it.
A slide presented by Aubrey de Grey, referencing his collaboration with Mike West at AgeX, showing the 7 types of damage that he believes must be repaired to end aging.
(Courtesy Kira Peikoff)
That's exciting. What do you think are the biggest barriers to defeating aging today: the technological challenges, the regulatory framework, the cost, or the cultural attitude of the "pro-aging" trance?
One can't really address those independently of each other. The technological side is one thing; it's hard, but we know where we're going, we've got a plan. The other ones are very intertwined with each other. A lot of people are inclined to say, the regulatory hurdle will be completely insurmountable, plus people don't recognize aging as a disease, so it's going to be a complete nonstarter. I think that's nonsense. And the reason is because the cultural attitudes toward all of this are going to be completely turned upside down before we have to worry about the regulatory hurdles. In other words, they're going to be turned upside down by sufficiently promising results in the lab, in mice. Once we get to be able to rejuvenate actually old mice really well so they live substantially longer than they otherwise would have done, in a healthy state, everyone's going to know about it and everyone's going to demand – it's not going to be possible to get re-elected unless you have a manifesto commitment to turn the FDA completely upside down and make sure this happens without any kind of regulatory obstacle.
I've been struggling away all these years trying to bring little bits of money in the door, and the reason I have is because of the skepticism as to regards whether this could actually work, combined with the pro-aging trance, which is a product of the skepticism – people not wanting to get their hopes up, so finding excuses about aging being a blessing in disguise, so they don't have to think about it. All of that will literally disintegrate pretty much overnight when we have the right kind of sufficiently impressive progress in the lab. Therefore, the availability of money will also [open up]. It's already cracking: we're already seeing the beginnings of the actual rejuvenation biotechnology industry that I've been talking about with a twinkle in my eye for some years.
"For humans, a 50-50 chance would be twenty years at this point, and there's a 10 percent chance that we won't get there for a hundred years."
Why do you think the culture is starting to shift?
There's no one thing yet. There will be that tipping point I mentioned, perhaps five years from now when we get a real breakthrough, decisive results in mice that make it simply impossible to carry on being fatalistic about all this. Prior to that, what we're already seeing is the impact of sheer old-school repeat advertising—me going out there, banging away and saying the same fucking thing again and again, and nobody saying anything that persuasively knocks me down. … And it's also the fact that we are making incremental amounts of progress, not just ourselves, but the scientific community generally. It has become incrementally more plausible that what I say might be true.
I'm sure you hate getting the timeline question, but if we're five years away from this breakthrough in mice, it's hard to resist asking—how far is that in terms of a human cure?
When I give any kind of timeframes, the only real care I have to take is to emphasize the variance. In this case I think we have got a 50-50 chance of getting to that tipping point in mice within five years from now, certainly it could be 10 or 15 years if we get unlucky. Similarly, for humans, a 50-50 chance would be twenty years at this point, and there's a 10 percent chance that we won't get there for a hundred years.
"I don't get people coming to me saying, well I don't think medicine for the elderly should be done because if it worked it would be a bad thing. People like to ignore this contradiction."
What would you tell skeptical people are the biggest benefits of a very long-lived population?
Any question about the longevity of people is the wrong question. Because the longevity that people fixate about so much will only ever occur as a side effect of health. However long ago you were born or however recently, if you're sick, you're likely to die fairly soon unless we can stop you being sick. Whereas if you're healthy, you're not. So if we do as well as we think we can do in terms of keeping people healthy and youthful however long ago they were born, then the side effect in terms of longevity and life expectancy is likely to be very large. But it's still a side effect, so the way that people actually ought to be—in fact have a requirement to be—thinking, is about whether they want people to be healthy.
Now I don't get people coming to me saying, well I don't think medicine for the elderly should be done because if it worked it would be a bad thing. People like to ignore this contradiction, they like to sweep it under the carpet and say, oh yeah, aging is totally a good thing.
People will never actually admit to the fact that what they are fundamentally saying is medicine for the elderly, if it actually works, would be bad, but still that is what they are saying.
Shifting gears a bit, I'm curious to find out which other radical visionaries in science and tech today you most admire?
Fair question. One is Mike West. I have the great privilege that I now work for him part-time with Age X. I have looked up to him very much for the past ten years, because what he did over the past 20 years starting with Geron is unimaginable today. He was working in an environment where I would not have dreamt of the possibility of getting any private money, any actual investment, in something that far out, that far ahead of its time, and he did it, again and again. It's insane what he managed to do.
What about someone like Elon Musk?
Sure, he's another one. He is totally impervious to the caution and criticism and conservatism that pervades humanity, and he's getting on making these bloody self-driving cars, space tourism, and so on, making them happen. He's thinking just the way I'm thinking really.
"You can just choose how frequently and how thoroughly you repair the damage. And you can make a different choice next time."
You famously said ten years ago that you think the first person to live to 1000 is already alive. Do you think that's still the case?
Definitely, yeah. I can't see how it could not be. Again, it's a probabilistic thing. I said there's at least a 10 percent chance that we won't get to what I call Longevity Escape Velocity for 100 years and if that's true, then the statement about 1000 years being alive already is not going to be the case. But for sure, I believe that the beneficiaries of what we may as well call SENS 1.0, the point where we get to LEV, those people are exceptionally unlikely ever to suffer from any kind of ill health correlated with their age. Because we will never fall below Longevity Escape Velocity once we attain it.
Could someone who was just born today expect—
I would say people in middle age now have a fair chance. Remember – a 50/50 chance of getting to LEV within 20 years, and when you get there, you don't just stay at biologically 70 or 80, you are rejuvenated back to biologically 30 or 40 and you stay there, so your risk of death each year is not related to how long ago you were born, it's the same as a young adult. Today, that's less than 1 in 1000 per year, and that number is going to go down as we get self-driving cars and all that, so actually 1000 is a very conservative number.
So you would be able to choose what age you wanted to go back to?
Oh sure, of course, it's just like a car. What you're doing is you're repairing damage, and the damage is still being created by the body's metabolism, so you can just choose how frequently and how thoroughly you repair the damage. And you can make a different choice next time.
What would be your perfect age?
I have no idea. That's something I don't have an opinion about, because I could change it whenever I like.
Kira Peikoff was the editor-in-chief of Leaps.org from 2017 to 2021. As a journalist, her work has appeared in The New York Times, Newsweek, Nautilus, Popular Mechanics, The New York Academy of Sciences, and other outlets. She is also the author of four suspense novels that explore controversial issues arising from scientific innovation: Living Proof, No Time to Die, Die Again Tomorrow, and Mother Knows Best. Peikoff holds a B.A. in Journalism from New York University and an M.S. in Bioethics from Columbia University. She lives in New Jersey with her husband and two young sons. Follow her on Twitter @KiraPeikoff.
Creamy milk with velvety texture. Dark with sprinkles of sea salt. Crunchy hazelnut-studded chunks. Chocolate is a treat that appeals to billions of people worldwide, no matter the age. And it’s not only the taste, but the feel of a chocolate morsel slowly melting in our mouths—the smoothness and slipperiness—that’s part of the overwhelming satisfaction. Why is it so enjoyable?
That’s what an interdisciplinary research team of chocolate lovers from the University of Leeds School of Food Science and Nutrition and School of Mechanical Engineering in the U.K. resolved to study in 2021. They wanted to know, “What is making chocolate that desirable?” says Siavash Soltanahmadi, one of the lead authors of a new study about chocolates hedonistic quality.
Besides addressing the researchers’ general curiosity, their answers might help chocolate manufacturers make the delicacy even more enjoyable and potentially healthier. After all, chocolate is a billion-dollar industry. Revenue from chocolate sales, whether milk or dark, is forecasted to grow 13 percent by 2027 in the U.K. In the U.S., chocolate and candy sales increased by 11 percent from 2020 to 2021, on track to reach $44.9 billion by 2026. Figuring out how chocolate affects the human palate could up the ante even more.
Building a 3D tongue
The team began by building a 3D tongue to analyze the physical process by which chocolate breaks down inside the mouth.
As part of the effort, reported earlier this year in the scientific journal ACS Applied Materials and Interfaces, the team studied a large variety of human tongues with the intention to build an “average” 3D model, says Soltanahmadi, a lubrication scientist. When it comes to edible substances, lubrication science looks at how food feels in the mouth and can help design foods that taste better and have more satisfying texture or health benefits.
There are variations in how people enjoy chocolate; some chew it while others “lick it” inside their mouths.
Tongue impressions from human participants studied using optical imaging helped the team build a tongue with key characteristics. “Our tongue is not a smooth muscle, it’s got some texture, it has got some roughness,” Soltanahmadi says. From those images, the team came up with a digital design of an average tongue and, using 3D printed molds, built a “mimic tongue.” They also added elastomers—such as silicone or polyurethane—to mimic the roughness, the texture and the mechanical properties of a real tongue. “Wettability" was another key component of the 3D tongue, Soltanahmadi says, referring to whether a surface mixes with water (hydrophilic) or, in the case of oil, resists it (hydrophobic).
Notably, the resulting artificial 3D-tongues looked nothing like the human version, but they were good mimics. The scientists also created “testing kits” that produced data on various physical parameters. One such parameter was viscosity, the measure of how gooey a food or liquid is — honey is more viscous compared to water, for example. Another was tribology, which defines how slippery something is — high fat yogurt is more slippery than low fat yogurt; milk can be more slippery than water. The researchers then mixed chocolate with artificial saliva and spread it on the 3D tongue to measure the tribology and the viscosity. From there they were able to study what happens inside the mouth when we eat chocolate.
The team focused on the stages of lubrication and the location of the fat in the chocolate, a process that has rarely been researched.
The artificial 3D-tongues look nothing like human tongues, but they function well enough to do the job.
Courtesy Anwesha Sarkar and University of Leeds
The oral processing of chocolate
We process food in our mouths in several stages, Soltanahmadi says. And there is variation in these stages depending on the type of food. So, the oral processing of a piece of meat would be different from, say, the processing of jelly or popcorn.
There are variations with chocolate, in particular; some people chew it while others use their tongues to explore it (within their mouths), Soltanahmadi explains. “Usually, from a consumer perspective, what we find is that if you have a luxury kind of a chocolate, then people tend to start with licking the chocolate rather than chewing it.” The researchers used a luxury brand of dark chocolate and focused on the process of licking rather than chewing.
As solid cocoa particles and fat are released, the emulsion envelops the tongue and coats the palette creating a smooth feeling of chocolate all over the mouth. That tactile sensation is part of the chocolate’s hedonistic appeal we crave.
Understanding the make-up of the chocolate was also an important step in the study. “Chocolate is a composite material. So, it has cocoa butter, which is oil, it has some particles in it, which is cocoa solid, and it has sugars," Soltanahmadi says. "Dark chocolate has less oil, for example, and less sugar in it, most of the time."
The researchers determined that the oral processing of chocolate begins as soon as it enters a person’s mouth; it starts melting upon exposure to one’s body temperature, even before the tongue starts moving, Soltanahmadi says. Then, lubrication begins. “[Saliva] mixes with the oily chocolate and it makes an emulsion." An emulsion is a fluid with a watery (or aqueous) phase and an oily phase. As chocolate breaks down in the mouth, that solid piece turns into a smooth emulsion with a fatty film. “The oil from the chocolate becomes droplets in a continuous aqueous phase,” says Soltanahmadi. In other words, as solid cocoa particles and fat are released, the emulsion envelops the tongue and coats the palette, creating a smooth feeling of chocolate all over the mouth. That tactile sensation is part of the chocolate’s hedonistic appeal we crave, says Soltanahmadi.
Finding the sweet spot
After determining how chocolate is orally processed, the research team wanted to find the exact sweet spot of the breakdown of solid cocoa particles and fat as they are released into the mouth. They determined that the epicurean pleasure comes only from the chocolate's outer layer of fat; the secondary fatty layers inside the chocolate don’t add to the sensation. It was this final discovery that helped the team determine that it might be possible to produce healthier chocolate that would contain less oil, says Soltanahmadi. And therefore, less fat.
Rongjia Tao, a physicist at Temple University in Philadelphia, thinks the Leeds study and the concept behind it is “very interesting.” Tao, himself, did a study in 2016 and found he could reduce fat in milk chocolate by 20 percent. He believes that the Leeds researchers’ discovery about the first layer of fat being more important for taste than the other layer can inform future chocolate manufacturing. “As a scientist I consider this significant and an important starting point,” he says.
Chocolate is rich in polyphenols, naturally occurring compounds also found in fruits and vegetables, such as grapes, apples and berries. Research found that plant polyphenols can protect against cancer, diabetes and osteoporosis as well as cardiovascular ad neurodegenerative diseases.
Not everyone thinks it’s a good idea, such as chef Michael Antonorsi, founder and owner of Chuao Chocolatier, one of the leading chocolate makers in the U.S. First, he says, “cacao fat is definitely a good fat.” Second, he’s not thrilled that science is trying to interfere with nature. “Every time we've tried to intervene and change nature, we get things out of balance,” says Antonorsi. “There’s a reason cacao is botanically known as food of the gods. The botanical name is the Theobroma cacao: Theobroma in ancient Greek, Theo is God and Brahma is food. So it's a food of the gods,” Antonorsi explains. He’s doubtful that a chocolate made only with a top layer of fat will produce the same epicurean satisfaction. “You're not going to achieve the same sensation because that surface fat is going to dissipate and there is no fat from behind coming to take over,” he says.
Without layers of fat, Antonorsi fears the deeply satisfying experiential part of savoring chocolate will be lost. The University of Leeds team, however, thinks that it may be possible to make chocolate healthier - when consumed in limited amounts - without sacrificing its taste. They believe the concept of less fatty but no less slick chocolate will resonate with at least some chocolate-makers and consumers, too.
Chocolate already contains some healthful compounds. Its cocoa particles have “loads of health benefits,” says Soltanahmadi. Dark chocolate usually has more cocoa than milk chocolate. Some experts recommend that dark chocolate should contain at least 70 percent cocoa in order for it to offer some health benefit. Research has shown that the cocoa in chocolate is rich in polyphenols, naturally occurring compounds also found in fruits and vegetables, such as grapes, apples and berries. Research has shown that consuming plant polyphenols can be protective against cancer, diabetes and osteoporosis as well as cardiovascular and neurodegenerative diseases.
“So keeping the healthy part of it and reducing the oily part of it, which is not healthy, but is giving you that indulgence of it … that was the final aim,” Soltanahmadi says. He adds that the team has been approached by individuals in the chocolate industry about their research. “Everyone wants to have a healthy chocolate, which at the same time tastes brilliant and gives you that self-indulging experience.”
In 1945, almost two decades after Alexander Fleming discovered penicillin, he warned that as antibiotics use grows, they may lose their efficiency. He was prescient—the first case of penicillin resistance was reported two years later. Back then, not many people paid attention to Fleming’s warning. After all, the “golden era” of the antibiotics age had just began. By the 1950s, three new antibiotics derived from soil bacteria — streptomycin, chloramphenicol, and tetracycline — could cure infectious diseases like tuberculosis, cholera, meningitis and typhoid fever, among others.
Today, these antibiotics and many of their successors developed through the 1980s are gradually losing their effectiveness. The extensive overuse and misuse of antibiotics led to the rise of drug resistance. The livestock sector buys around 80 percent of all antibiotics sold in the U.S. every year. Farmers feed cows and chickens low doses of antibiotics to prevent infections and fatten up the animals, which eventually causes resistant bacterial strains to evolve. If manure from cattle is used on fields, the soil and vegetables can get contaminated with antibiotic-resistant bacteria. Another major factor is doctors overprescribing antibiotics to humans, particularly in low-income countries. Between 2000 to 2018, the global rates of human antibiotic consumption shot up by 46 percent.
In recent years, researchers have been exploring a promising avenue: the use of synthetic biology to engineer new bacteria that may work better than antibiotics. The need continues to grow, as a Lancet study linked antibiotic resistance to over 1.27 million deaths worldwide in 2019, surpassing HIV/AIDS and malaria. The western sub-Saharan Africa region had the highest death rate (27.3 people per 100,000).
Researchers warn that if nothing changes, by 2050, antibiotic resistance could kill 10 million people annually.
To make it worse, our remedy pipelines are drying up. Out of the 18 biggest pharmaceutical companies, 15 abandoned antibiotic development by 2013. According to the AMR Action Fund, venture capital has remained indifferent towards biotech start-ups developing new antibiotics. In 2019, at least two antibiotic start-ups filed for bankruptcy. As of December 2020, there were 43 new antibiotics in clinical development. But because they are based on previously known molecules, scientists say they are inadequate for treating multidrug-resistant bacteria. Researchers warn that if nothing changes, by 2050, antibiotic resistance could kill 10 million people annually.
The rise of synthetic biology
To circumvent this dire future, scientists have been working on alternative solutions using synthetic biology tools, meaning genetically modifying good bacteria to fight the bad ones.
From the time life evolved on earth around 3.8 billion years ago, bacteria have engaged in biological warfare. They constantly strategize new methods to combat each other by synthesizing toxic proteins that kill competition.
For example, Escherichia coli produces bacteriocins or toxins to kill other strains of E.coli that attempt to colonize the same habitat. Microbes like E.coli (which are not all pathogenic) are also naturally present in the human microbiome. The human microbiome harbors up to 100 trillion symbiotic microbial cells. The majority of them are beneficial organisms residing in the gut at different compositions.
The chemicals that these “good bacteria” produce do not pose any health risks to us, but can be toxic to other bacteria, particularly to human pathogens. For the last three decades, scientists have been manipulating bacteria’s biological warfare tactics to our collective advantage.
In the late 1990s, researchers drew inspiration from electrical and computing engineering principles that involve constructing digital circuits to control devices. In certain ways, every cell in living organisms works like a tiny computer. The cell receives messages in the form of biochemical molecules that cling on to its surface. Those messages get processed within the cells through a series of complex molecular interactions.
Synthetic biologists can harness these living cells’ information processing skills and use them to construct genetic circuits that perform specific instructions—for example, secrete a toxin that kills pathogenic bacteria. “Any synthetic genetic circuit is merely a piece of information that hangs around in the bacteria’s cytoplasm,” explains José Rubén Morones-Ramírez, a professor at the Autonomous University of Nuevo León, Mexico. Then the ribosome, which synthesizes proteins in the cell, processes that new information, making the compounds scientists want bacteria to make. “The genetic circuit remains separated from the living cell’s DNA,” Morones-Ramírez explains. When the engineered bacteria replicates, the genetic circuit doesn’t become part of its genome.
Highly intelligent by bacterial standards, some multidrug resistant V. cholerae strains can also “collaborate” with other intestinal bacterial species to gain advantage and take hold of the gut.
In 2000, Boston-based researchers constructed an E.coli with a genetic switch that toggled between turning genes on and off two. Later, they built some safety checks into their bacteria. “To prevent unintentional or deleterious consequences, in 2009, we built a safety switch in the engineered bacteria’s genetic circuit that gets triggered after it gets exposed to a pathogen," says James Collins, a professor of biological engineering at MIT and faculty member at Harvard University’s Wyss Institute. “After getting rid of the pathogen, the engineered bacteria is designed to switch off and leave the patient's body.”
Overuse and misuse of antibiotics causes resistant strains to evolve
Adobe Stock
Seek and destroy
As the field of synthetic biology developed, scientists began using engineered bacteria to tackle superbugs. They first focused on Vibrio cholerae, which in the 19th and 20th century caused cholera pandemics in India, China, the Middle East, Europe, and Americas. Like many other bacteria, V. cholerae communicate with each other via quorum sensing, a process in which the microorganisms release different signaling molecules, to convey messages to its brethren. Highly intelligent by bacterial standards, some multidrug resistant V. cholerae strains can also “collaborate” with other intestinal bacterial species to gain advantage and take hold of the gut. When untreated, cholera has a mortality rate of 25 to 50 percent and outbreaks frequently occur in developing countries, especially during floods and droughts.
Sometimes, however, V. cholerae makes mistakes. In 2008, researchers at Cornell University observed that when quorum sensing V. cholerae accidentally released high concentrations of a signaling molecule called CAI-1, it had a counterproductive effect—the pathogen couldn’t colonize the gut.
So the group, led by John March, professor of biological and environmental engineering, developed a novel strategy to combat V. cholerae. They genetically engineered E.coli to eavesdrop on V. cholerae communication networks and equipped it with the ability to release the CAI-1 molecules. That interfered with V. cholerae progress. Two years later, the Cornell team showed that V. cholerae-infected mice treated with engineered E.coli had a 92 percent survival rate.
These findings inspired researchers to sic the good bacteria present in foods like yogurt and kimchi onto the drug-resistant ones.
Three years later in 2011, Singapore-based scientists engineered E.coli to detect and destroy Pseudomonas aeruginosa, an often drug-resistant pathogen that causes pneumonia, urinary tract infections, and sepsis. Once the genetically engineered E.coli found its target through its quorum sensing molecules, it then released a peptide, that could eradicate 99 percent of P. aeruginosa cells in a test-tube experiment. The team outlined their work in a Molecular Systems Biology study.
“At the time, we knew that we were entering new, uncharted territory,” says lead author Matthew Chang, an associate professor and synthetic biologist at the National University of Singapore and lead author of the study. “To date, we are still in the process of trying to understand how long these microbes stay in our bodies and how they might continue to evolve.”
More teams followed the same path. In a 2013 study, MIT researchers also genetically engineered E.coli to detect P. aeruginosa via the pathogen’s quorum-sensing molecules. It then destroyed the pathogen by secreting a lab-made toxin.
Probiotics that fight
A year later in 2014, a Nature study found that the abundance of Ruminococcus obeum, a probiotic bacteria naturally occurring in the human microbiome, interrupts and reduces V.cholerae’s colonization— by detecting the pathogen’s quorum sensing molecules. The natural accumulation of R. obeum in Bangladeshi adults helped them recover from cholera despite living in an area with frequent outbreaks.
The findings from 2008 to 2014 inspired Collins and his team to delve into how good bacteria present in foods like yogurt and kimchi can attack drug-resistant bacteria. In 2018, Collins and his team developed the engineered probiotic strategy. They tweaked a bacteria commonly found in yogurt called Lactococcus lactis to treat cholera.
Engineered bacteria can be trained to target pathogens when they are at their most vulnerable metabolic stage in the human gut. --José Rubén Morones-Ramírez.
More scientists followed with more experiments. So far, researchers have engineered various probiotic organisms to fight pathogenic bacteria like Staphylococcus aureus (leading cause of skin, tissue, bone, joint and blood infections) and Clostridium perfringens (which causes watery diarrhea) in test-tube and animal experiments. In 2020, Russian scientists engineered a probiotic called Pichia pastoris to produce an enzyme called lysostaphin that eradicated S. aureus in vitro. Another 2020 study from China used an engineered probiotic bacteria Lactobacilli casei as a vaccine to prevent C. perfringens infection in rabbits.
In a study last year, Ramírez’s group at the Autonomous University of Nuevo León, engineered E. coli to detect quorum-sensing molecules from Methicillin-resistant Staphylococcus aureus or MRSA, a notorious superbug. The E. coli then releases a bacteriocin that kills MRSA. “An antibiotic is just a molecule that is not intelligent,” says Ramírez. “On the other hand, engineered bacteria can be trained to target pathogens when they are at their most vulnerable metabolic stage in the human gut.”
Collins and Timothy Lu, an associate professor of biological engineering at MIT, found that engineered E. coli can help treat other conditions—such as phenylketonuria, a rare metabolic disorder, that causes the build-up of an amino acid phenylalanine. Their start-up Synlogic aims to commercialize the technology, and has completed a phase 2 clinical trial.
Circumventing the challenges
The bacteria-engineering technique is not without pitfalls. One major challenge is that beneficial gut bacteria produce their own quorum-sensing molecules that can be similar to those that pathogens secrete. If an engineered bacteria’s biosensor is not specific enough, it will be ineffective.
Another concern is whether engineered bacteria might mutate after entering the gut. “As with any technology, there are risks where bad actors could have the capability to engineer a microbe to act quite nastily,” says Collins of MIT. But Collins and Ramírez both insist that the chances of the engineered bacteria mutating on its own are virtually non-existent. “It is extremely unlikely for the engineered bacteria to mutate,” Ramírez says. “Coaxing a living cell to do anything on command is immensely challenging. Usually, the greater risk is that the engineered bacteria entirely lose its functionality.”
However, the biggest challenge is bringing the curative bacteria to consumers. Pharmaceutical companies aren’t interested in antibiotics or their alternatives because it’s less profitable than developing new medicines for non-infectious diseases. Unlike the more chronic conditions like diabetes or cancer that require long-term medications, infectious diseases are usually treated much quicker. Running clinical trials are expensive and antibiotic-alternatives aren’t lucrative enough.
“Unfortunately, new medications for antibiotic resistant infections have been pushed to the bottom of the field,” says Lu of MIT. “It's not because the technology does not work. This is more of a market issue. Because clinical trials cost hundreds of millions of dollars, the only solution is that governments will need to fund them.” Lu stresses that societies must lobby to change how the modern healthcare industry works. “The whole world needs better treatments for antibiotic resistance.”