Scientists want the salamander's secret: how they regenerate tissue
All organisms have the capacity to repair or regenerate tissue damage. None can do it better than salamanders or newts, which can regenerate an entire severed limb.
That feat has amazed and delighted man from the dawn of time and led to endless attempts to understand how it happens – and whether we can control it for our own purposes. An exciting new clue toward that understanding has come from a surprising source: research on the decline of cells, called cellular senescence.
Senescence is the last stage in the life of a cell. Whereas some cells simply break up or wither and die off, others transition into a zombie-like state where they can no longer divide. In this liminal phase, the cell still pumps out many different molecules that can affect its neighbors and cause low grade inflammation. Senescence is associated with many of the declining biological functions that characterize aging, such as inflammation and genomic instability.
Oddly enough, newts are one of the few species that do not accumulate senescent cells as they age, according to research over several years by Maximina Yun. A research group leader at the Center for Regenerative Therapies Dresden and the Max Planck Institute of Molecular and Cell Biology and Genetics, in Dresden, Germany, Yun discovered that senescent cells were induced at some stages of regeneration of the salamander limb, “and then, as the regeneration progresses, they disappeared, they were eliminated by the immune system,” she says. “They were present at particular times and then they disappeared.”
Senescent cells added to the edges of the wound helped the healthy muscle cells to “dedifferentiate,” essentially turning back the developmental clock of those cells into more primitive states.
Previous research on senescence in aging had suggested, logically enough, that applying those cells to the stump of a newly severed salamander limb would slow or even stop its regeneration. But Yun stood that idea on its head. She theorized that senescent cells might also play a role in newt limb regeneration, and she tested it by both adding and removing senescent cells from her animals. It turned out she was right, as the newt limbs grew back faster than normal when more senescent cells were included.
Senescent cells added to the edges of the wound helped the healthy muscle cells to “dedifferentiate,” essentially turning back the developmental clock of those cells into more primitive states, which could then be turned into progenitors, a cell type in between stem cells and specialized cells, needed to regrow the muscle tissue of the missing limb. “We think that this ability to dedifferentiate is intrinsically a big part of why salamanders can regenerate all these very complex structures, which other organisms cannot,” she explains.
Yun sees regeneration as a two part problem. First, the cells must be able to sense that their neighbors from the lost limb are not there anymore. Second, they need to be able to produce the intermediary progenitors for regeneration, , to form what is missing. “Molecularly, that must be encoded like a 3D map,” she says, otherwise the new tissue might grow back as a blob, or liver, or fin instead of a limb.
Wound healing
Another recent study, this time at the Mayo Clinic, provides evidence supporting the role of senescent cells in regeneration. Looking closely at molecules that send information between cells in the wound of a mouse, the researchers found that senescent cells appeared near the start of the healing process and then disappeared as healing progressed. In contrast, persistent senescent cells were the hallmark of a chronic wound that did not heal properly. The function and significance of senescence cells depended on both the timing and the context of their environment.
The paper suggests that senescent cells are not all the same. That has become clearer as researchers have been able to identify protein markers on the surface of some senescent cells. The patterns of these proteins differ for some senescent cells compared to others. In biology, such physical differences suggest functional differences, so it is becoming increasingly likely there are subsets of senescent cells with differing functions that have not yet been identified.
There are disagreements within the research community as to whether newts have acquired their regenerative capacity through a unique evolutionary change, or if other animals, including humans, retain this capacity buried somewhere in their genes.
Scientists initially thought that senescent cells couldn’t play a role in regeneration because they could no longer reproduce, says Anthony Atala, a practicing surgeon and bioengineer who leads the Wake Forest Institute for Regenerative Medicine in North Carolina. But Yun’s study points in the other direction. “What this paper shows clearly is that these cells have the potential to be involved in tissue regeneration [in newts]. The question becomes, will these cells be able to do the same in humans.”
As our knowledge of senescent cells increases, Atala thinks we need to embrace a new analogy to help understand them: humans in retirement. They “have acquired a lot of wisdom throughout their whole life and they can help younger people and mentor them to grow to their full potential. We're seeing the same thing with these cells,” he says. They are no longer putting energy into their own reproduction, but the signaling molecules they secrete “can help other cells around them to regenerate.”
There are disagreements within the research community as to whether newts have acquired their regenerative capacity through a unique evolutionary change, or if other animals, including humans, retain this capacity buried somewhere in their genes. If so, it seems that our genes are unable to express this ability, perhaps as part of a tradeoff in acquiring other traits. It is a fertile area of research.
Dedifferentiation is likely to become an important process in the field of regenerative medicine. One extreme example: a lab has been able to turn back the clock and reprogram adult male skin cells into female eggs, a potential milestone in reproductive health. It will be more difficult to control just how far back one wishes to go in the cell's dedifferentiation – part way or all the way back into a stem cell – and then direct it down a different developmental pathway. Yun is optimistic we can learn these tricks from newts.
Senolytics
A growing field of research is using drugs called senolytics to remove senescent cells and slow or even reverse disease of aging.
“Senolytics are great, but senolytics target different types of senescence,” Yun says. “If senescent cells have positive effects in the context of regeneration, of wound healing, then maybe at the beginning of the regeneration process, you may not want to take them out for a little while.”
“If you look at pretty much all biological systems, too little or too much of something can be bad, you have to be in that central zone” and at the proper time, says Atala. “That's true for proteins, sugars, and the drugs that you take. I think the same thing is true for these cells. Why would they be different?”
Our growing understanding that senescence is not a single thing but a variety of things likely means that effective senolytic drugs will not resemble a single sledge hammer but more a carefully manipulated scalpel where some types of senescent cells are removed while others are added. Combinations and timing could be crucial, meaning the difference between regenerating healthy tissue, a scar, or worse.
The Fight Against Air Pollution Gets Personal With Sleek New Masks
Go outside, close your eyes, and inhale. Do your lungs fill with fresh air – or are you taking a big deep breath of nasty fumes?
A new crop of tech startups is emerging to meet a growing demand for individualized clean air.
It depends, of course, on where you live – and for many people, the situation is worsening. According to a recent analysis by two Carnegie Mellon economists, particulate air matter pollution rose 5.5 percent in the U.S. between 2016 and 2018, resulting in almost 10,000 premature deaths.
Despite the urgency of the problem, there seems to be no indication that civic leadership will be protecting our air any time soon. The United States left the Paris Agreement recently, Brazil is still letting the Amazon burn and Australia lacks a national strategy for tackling air pollution, despite its recent catastrophic bushfires. China's deceptive coronavirus communication only underscores the point that safeguarding the public's health can take a backseat to politics and power.
But people still need to breathe, and now a new crop of tech startups is emerging to meet a growing demand for individualized clean air. At the recent Consumer Electronics Show, I saw futuristic masks, smart goggles and self-contained apparatuses promising to filter the bad air away.
Obviously, a dollar store surgical mask wasn't going to cut it anymore.
"We have seen a huge amount of interest and a growing awareness of the issues with masks and respirators," says AO Air co-founder Dan Bowden. "The more regularly someone wears a mask or a respirator, the deeper our Atmos solution resonates with them. Leading markets have been Korea, China and, unexpectedly, Thailand."
Lined up for a Summer 2020 launch, the AO Air filter fits across your mouth from ear to ear – kind of like Geordi LaForge's Star Trek: The Next Generation eye sensors, but across your jaw line. The translucent mask continually pumps cool air for about 5 hours per charge and will cost $350 USD.
"Soon, we'll have private schools selling themselves on the air quality of the building."
"There is a movement towards individuals taking control over their own health, but also we see a great movement towards individuals taking control over the impacts that they have on the wider world," Bowden says. "We believe that the deeper systemic change has always come from humans working together and not being reliant upon high powers."
Bowden says the company wants to help the individual citizen, clean up the public building air ("factories, hospitals, workplaces") and, most interestingly, collect pollution metrics data via the masks. "We are looking forward to hearing how this information can be used in creative ways," Bowden adds. It is yet unclear how the data will be shared and how proprietary the information will be for AO Air and its competitors.
Scientific artist Michael Pinsky is taking a more experiential approach to raise awareness of the problem. In 2017, he launched traveling pollution pods, these giant, interconnected rooms recreating the air quality of several cities from London to Los Angeles. His exhibit has been on near constant tour, hitting the New York Climate Action Summit, the recent COP25 in Madrid, and other major events.
When I visited, I could handle being in the New Delhi air quality pod for only about 20 seconds. It made my eyes water and burn.
"Now you have new, 8 – 10 million British pound houses being built with premium air systems," Pinsky says. "Soon, we'll have private schools selling themselves on the air quality of the building." I mention my own children, whose schools we selected based on ratings and rankings. I could easily see "indoor air quality" being another metric. Perhaps another lever of privilege.
Pinsky gives a wily chuckle.
"The legislators have to get on top of it – or air will be privatized like space or our schools," he says.
"Clean air is a right," he adds. "Everyone should have it."
Americans Fell for a Theranos-Style Scam 100 Years Ago. Will We Ever Learn?
The huckster understands what people want – an easy route to good health -- and figures out just how to provide it as long as no one asks too many questions.
"Americans are very much prone to this sort of thinking: Give me a pill or give me a magical bean that can make me lose weight!"
The keys to success: Hoopla, fancy technology, and gullibility. And oh yes, one more thing: a blood sample. Well, lots and lots of blood samples. Every testing fee counts.
Sound familiar? It could be the story of the preternaturally persuasive Elizabeth Holmes, the disgraced founder of Theranos who stands accused of perpetrating a massive blood-testing fraud. But this is a different story from a different time, one that dates back 100 years but sounds almost like it could unfold on the front page of The Wall Street Journal today.
The main difference: Back then, watchdogs thought they'd be able to vanquish fake medicine and scam science. Fat chance, it turned out. It seems like we're more likely to lose-weight-quick than make much of a dent into quackery and health fraud.
Why? Have we learned anything at all over the past century? As we sweep into a new decade, experts says we're not as advanced as we'd like to think. But the fight against fraud and fakery continues.
Quackery: As American As America Itself
In the 17th century, British healers of questionable reputation got a new name -- "quack," from the Dutch word "quacksalver," which originally referred to someone who treats others with home remedies but developed a new meaning along the lines of "charlatan." And these quacks got a new place to sell their wares: the American colonies.
By 1692, a Boston newspaper advertised a patent medicine that promised to cure "the Griping of the Guts, and the Wind Cholick" and – for good measure – "preventeth that woeful Distemper of the Dry Belly Ach." A couple centuries later, the most famous woman in the United States wasn't a first lady or feminist but a hawker of nostrums named Lydia Estes Pinkham whose "vegetable compound" promised to banish "female complaints." One advertisement suggested that the "sure cure" would have saved the life of a Connecticut clergyman whose wife killed him after suffering from feminine maladies for 16 years.
By the early 20th century, Americans were fascinated by electricity and radiation, and both healers and hucksters embraced the new high-tech era. Men with flagging libidos, for example, could irradiate their private parts with the radioactive Radiendocrinator or buy battery-powered electric belts equipped with dangling bits to supercharge their, um, dangling bits.
The Rise of the Radio Wave 'Cure'
Enter radionics, the (supposed) science of better health via radio waves. The idea was that "healthy people radiate healthy energy," and sickness could be reversed through diagnosis and re-tuning, write Dr. Lydia Kang and Nate Pedersen in their 2017 book "Quackery: A Brief History of the Worst Ways to Cure Everything."
Detecting illness and fixing it required machinery -- Dynamizers, Radioclasts and Oscillocasts – that could cost hundreds of dollars each. Thousands of physicians bought them. Fortunately, they could work remotely, for a fee. The worried-and-potentially-unwell just needed to send a blood sample and, of course, a personal check.
Sting operations revealed radionics to be bogus. A skeptic sent a blood sample to one radionics practitioner in Albuquerque who reported back with news of an infected fallopian tube. In fact, the blood sample came from a male guinea pig. As an American Medical Association leader reported, the guinea pig "had shown no female characteristics up to that time, and a postmortem examination yielded no evidence of ladylike attributes."
When Quackery Refused to Yield
The rise of bogus medical technology in the early 20th century spawned a watchdog industry as organizations like the American Medical Association swept into action, said medical historian Eric Boyle, author of 2012's "Quack Medicine: A History of Combating Health Fraud in Twentieth-Century America."
"When quackery was recognized as a major problem, the people who campaigned for its demise were confident that they could get rid of it," he said. "A lot of people believed that increased education, the truths of science, and laws designed to protect consumers would ultimately drive quackery from the marketplace. And then throughout the century, as modern medicine developed, and more effectively treated one disease after another, many observers remained confident in that prediction."
There's a bid to "flood the information highway with truth to turn the storm of fake promotional stuff into a trickle."
But fake medicine persisted as Americans continued their quest to get- healthy-quick… or get-rich-quick by promising to help others to get- healthy-quick. Even radionics refused to die. It's still around in various forms. And, as the Theranos scandal reveals, we're still hoping our blood can offer the keys to longevity and good health.
Why Do We Still Fall for Scams?
In our own era, the Theranos company rose to prominence when founder and CEO Elizabeth Holmes convinced journalists and investors that she'd found a way to cheaply test drops of blood for hundreds of conditions. Then it all fell apart, famously, when the world learned that the technology didn't work. The company has folded, and Holmes faces a federal trial on fraud charges this year.
"There were a lot of prominent, very smart people who bought into the myth of Elizabeth Holmes," a former employee told "60 Minutes," even though the blood tests never actually worked as advertised.
Shouldn't "prominent, very smart people" know better? "People are gullible," said Dr. Stephen Barrett, a psychiatrist and leading quack-buster who runs the QuackWatch website. But there's more to the story. According to him, we're uniquely vulnerable as individuals to bogus medicine.
Scam artists specifically pinpoint their target audiences, such as "smart people," desperate people and alienated people, he said.
Smart people, for example, might be overconfident about their ability to detect fraud and fall for bogus medicine. Alienated people may distrust the establishment, whether it's the medical field or government watchdogs, and be more receptive to alternative sources of information.
Dr. Barrett also points a finger at magical thinking, which comes in different forms. It could mean a New Age-style belief that our minds can control the world around us. Or, as professional quack-buster Alex Berezow said, it could refer to "our cultural obsession with quick fixes."
"Americans are very much prone to this sort of thinking: Give me a pill or give me a magical bean that can make me lose weight! But complex problems need complex solutions," said Berezow, a microbiologist who debunks junk science in his job as a spokesman for the American Council on Science & Health.
American mistrust of expertise makes matters worse, he said. "When I tell people they need to get vaccinated, I'm called a shill for the pharmaceutical industry," he said. "If I say dietary supplements generally don't work, I'm a shill for doctors who want to keep people sick."
What can ordinary citizens do to protect themselves from fake medicine? "You have to have a healthy skepticism of everything," Berezow said. "When you come across something new, is someone trying to take advantage of you? It's a horrible way to think about the world, but there's some truth to it."
"Like any chronic disease, we will have to live with it while we do our best to fight it."
The government and experts have their own roles to play via regulation and education, respectively. For all the criticism it gets, the Food & Drug Administration does serve as a bulwark against fakery in prescription medicine. And while celebrities like Gwyneth "Goop" Paltrow hawk countless questionable medical products on the Internet, scientists and physicians are fighting back by using social media as a tool to promote the truth. There's a bid to "flood the information highway with truth to turn the storm of fake promotional stuff into a trickle," said Dr. Randi Hutter Epstein, a writer in residence at Yale School of Medicine and author of 2018's "Aroused: The History of Hormones and How They Control Just About Everything."
What's next? Like death, taxes and Cher, charlatans are likely to always be with us. Boyle quoted the late William Jarvis, a pioneering quack-buster in the late 20th century who believed health fraud would never be eradicated: "Like any chronic disease, we will have to live with it while we do our best to fight it."