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.
A Mother-and-Daughter Team Have Developed What May Be the World’s First Alzheimer’s Vaccine
Alzheimer's is a terrible disease that robs a person of their personality and memory before eventually leading to death. It's the sixth-largest killer in the U.S. and, currently, there are 5.8 million Americans living with the disease.
Wang's vaccine is a significant improvement over previous attempts because it can attack the Alzheimer's protein without creating any adverse side effects.
It devastates people and families and it's estimated that Alzheimer's and other forms of dementia will cost the U.S. $290 billion dollars this year alone. It's estimated that it will become a trillion-dollar-a-year disease by 2050.
There have been over 200 unsuccessful attempts to find a cure for the disease and the clinical trial termination rate is 98 percent.
Alzheimer's is caused by plaque deposits that develop in brain tissue that become toxic to brain cells. One of the major hurdles to finding a cure for the disease is that it's impossible to clear out the deposits from the tissue. So scientists have turned their attention to early detection and prevention.
One very encouraging development has come out of the work done by Dr. Chang Yi Wang, PhD. Wang is a prolific bio-inventor; one of her biggest successes is developing a foot-and-mouth vaccine for pigs that has been administered more than three billion times.
Mei Mei Hu
Brainstorm Health / Flickr.
In January, United Neuroscience, a biotech company founded by Yi, her daughter Mei Mei Hu, and son-in-law, Louis Reese, announced the first results from a phase IIa clinical trial on UB-311, an Alzheimer's vaccine.
The vaccine has synthetic versions of amino acid chains that trigger antibodies to attack Alzheimer's protein the blood. Wang's vaccine is a significant improvement over previous attempts because it can attack the Alzheimer's protein without creating any adverse side effects.
"We were able to generate some antibodies in all patients, which is unusual for vaccines," Yi told Wired. "We're talking about almost a 100 percent response rate. So far, we have seen an improvement in three out of three measurements of cognitive performance for patients with mild Alzheimer's disease."
The researchers also claim it can delay the onset of the disease by five years. While this would be a godsend for people with the disease and their families, according to Elle, it could also save Medicare and Medicaid more than $220 billion.
"You'd want to see larger numbers, but this looks like a beneficial treatment," James Brown, director of the Aston University Research Centre for Healthy Ageing, told Wired. "This looks like a silver bullet that can arrest or improve symptoms and, if it passes the next phase, it could be the best chance we've got."
"A word of caution is that it's a small study," says Drew Holzapfel, acting president of the nonprofit UsAgainstAlzheimer's, said according to Elle. "But the initial data is compelling."
The company is now working on its next clinical trial of the vaccine and while hopes are high, so is the pressure. The company has already invested $100 million developing its vaccine platform. According to Reese, the company's ultimate goal is to create a host of vaccines that will be administered to protect people from chronic illness.
"We have a 50-year vision -- to immuno-sculpt people against chronic illness and chronic aging with vaccines as prolific as vaccines for infectious diseases," he told Elle.
[Editor's Note: This article was originally published by Upworthy here and has been republished with permission.]
Turning Algae Into Environmentally Friendly Fuel Just Got Faster and Smarter
Was your favorite beach closed this summer? Algae blooms are becoming increasingly the reason to blame and, as the climate heats up, scientists say we can expect more of the warm water-loving blue-green algae to grow.
"We have removed a significant development barrier to make algal biofuel production more efficient and smarter."
Oddly enough, the pesky growth could help fuel our carbon-friendly options.
This year, the University of Utah scientists discovered a faster way to turn algae into fuel. Algae is filled with lipids that we can feed our energy-hungry diesel engines. The problem is extracting the lipids, which usually requires more energy to transform than the actual energy we'd get – not achieving what scientists call "energy parity."
But now, the University of Utah team has discovered a new mix that is more efficient and much faster. We can now extract more power from algae with less waste materials after the fact. Paper co-author Dr. Leonard Pease says, "We have removed a significant development barrier to make algal biofuel production more efficient and smarter. Our method puts us much closer to creating biofuels energy parity than we were before."
Next Up
Algae has a lot going for it as an alternative fuel source. It grows fast and easily, absorbs carbon dioxide, does not compete with food crops for land, and could produce up to 60 times more oil than standard land-based energy crops, according to the U.S. Department of Energy. Yet the costs of algal biofuel production are still expensive for now.
According to Science Daily, only about five percent of total primary energy use in the United States came from algae and other biomass forms. By making the process more efficient, America and other nations could potentially begin relying on more plentiful resources – which, ironically, are more common now because of climate change.
Algae fuel efficiency is already a proven concept. A decade ago, Continental Airlines completed a 90-minute Boeing 737-800 flight with one engine split between biofuel and aircraft fuel. The biofuel was straight from algae. (Other flights were done based on nut fuel and other alternative sources.) The commercial airplane required no modification to the engine and the biofuel itself exceeded the standards of traditional jet fuel.
The problem, as noted at the time, is that biofuels derived from algae had yet to be proven as "commercially competitive."
The University of Utah's discovery could mean cheaper processing. At this point, it is less about if it works and more about if it is a practical alternative.
However, it's unclear how long it will take for algae to become more mainstream, if ever.
Open Questions
Higher efficiency and simpler transformations could mean lower prices and more business access. However, it's unclear how long it will take for algae to become more mainstream, if ever. The algae biofuel worked great for a relatively sophisticated Boeing 737 engine, but your family car, the cross-country delivery trucks and other less powerful machines may need to be modified – and that means the industry-at-large would have to revise their products in order to support the change.
Future-focused groups are already looking at how algae can fuel our space programs, especially if it is more renewable, safe and, potentially, cheaper than our traditional fuel choices. But first, it is worth waiting and seeing if corporations and, later, citizens are willing to take the plunge.