.

Tiangong included an experiment in which atoms were cooled to 10 picokelvins, which is barely above absolute zero, the coldest theoretical temperature possible in physics. Absolute zero is minus 459.67 degrees Fahrenheit (minus 273.15 degrees Celsius) and the threshold at which all particles in an object are believed to stop moving.

Scientists hit the mark using "optical tweezers," known more formally as an optical-dipole trap (ODT), which hold atoms in a laser beam," the scientists reported Nov. 5 in the journal Science.

The team placed 20,000 rubidium atoms in the trap in order to restrict their motion. This reduced motion, along with the weightlessness induced by the low-gravity environment aboard the space station, caused the cloud of atoms to cool to much lower temperatures than are possible on Earth.

The experiment's results could help improve future space-based research, the team said.

"This record-low temperature could stimulate a new generation of ODT-based experiments in quantum simulation and precision measurements in space," the researchers wrote in the paper.

How low can you go?

Despite this achievement, it's doubtful that scientists could ever hit absolute zero. One interpretation of the third law of thermodynamics, which looks at how systems behave when they approach absolute zero, is that the particles would always have a bit of entropy (disorder) associated with them, making absolute zero unachievable.

"One version of the third law states that it would require an infinite number of steps to reach absolute zero, which means you will never get there," Saibal Mitra, a professor of physics at Missouri State University, told Live Science in a 2024 interview.

The second law of thermodynamics, which states that entropy always increases, would also be violated if scientists could reach absolute zero, he added. "If you had a heat sink at absolute zero, then you could build a machine that was 100% efficient," Mitra said.

That said, space makes it easier to get close to absolute zero because microgravity allows atoms to "float" and become more efficient at cooling, Science News reported. The researchers took their weightless collection of atoms and created a quantum state of matter known as a Bose-Einstein condensate, in which very cold atoms clump and create a "fifth state" of matter as they behave akin to a single atom.

Tiangong's very cold clump follows similar experiments on the International Space Station that reached 52 picokelvins and from a weightless fall induced by a drop from a tall tower, in which atoms hit 38 picokelvins, Science News added.

'> Chinese scientists cool atoms to near absolute zero in record-breaking experiment often used to treat acne, respiratory infections and sexually transmitted infections, such as chlamydia and syphilis. Doctors generally avoid prescribing the drug during the second and third trimesters because it belongs to a class of antibiotics that can bind to calcium in developing bones. Animal studies suggest that this may disrupt fetal bone development.

However, evidence on doxycycline's safety during early pregnancy has been mixed and limited. The new study, published Tuesday (Nov. 10) in the journal Annals of Internal Medicine, provides clearer evidence of a link between doxycycline use in the first trimester and pregnancy loss.

"I would advise physicians to carefully consider the benefit-risk balance when prescribing doxycycline to women who are pregnant or planning a pregnancy," study first author Almut Winterstein, a pharmacist and drug-safety researcher at the University of Florida, told Live Science in an email.

A higher risk than other antibiotics

Using information from two U.S. insurance databases, the researchers analyzed 224,870 pregnancies in people ages 12 to 55. More than 218,230 of these patients were treated for respiratory tract infections, and over 6,630 were treated for acne, between conception and the end of the first trimester. About 4,385 of the women filled a prescription for doxycycline during that time frame, while the others received an alternative antibiotic.

Among women with respiratory infections, those prescribed doxycycline had a 40% to 54% higher risk of pregnancy loss, compared with those prescribed amoxicillin, another broad-spectrum antibiotic in a different class. The exact level of risk varied between the two databases.

The researchers also compared the doxycycline users against women prescribed macrolides, the class of antibiotics that includes azithromycin (or "Z-Pak"). Again, the doxycycline users saw a higher risk — 39% and 36% higher, respectively.

Among the patients treated for acne, doxycycline users had a 49% higher risk of pregnancy loss in one database than those given the antibiotic clindamycin. In the second database, though, the difference wasn't statistically significant. Winterstein said that may be because there were fewer patients included in that analysis.

Overall, doxycycline was associated with seven to 11 additional pregnancy losses per 100 pregnancies, compared with the other antibiotic options assessed, the researchers reported.

What drives the risk?

It is not yet clear how the drug might contribute to pregnancy loss. Because the study was observational, it cannot prove that the antibiotic itself caused those losses, which included miscarriages and stillbirths. (Miscarriage is pregnancy loss before 20 weeks of pregnancy, whereas stillbirth refers to pregnancy loss after the 20th week.)

Animal studies hint that doxycycline could interfere with early placental development, potentially making it harder for the placenta to support a growing pregnancy, Luke Grzeskowiak, an associate professor and clinical pharmacist at Flinders University in Australia who was not involved in the study, said in an email.

The study authors also noted in their report that the drug may have direct effects on the developing embryo. But these explanations remain hypothetical; the researchers have not established that either mechanism occurs in humans.

"Pregnancy loss affects around one in four pregnancies and can happen for many reasons," Grzeskowiak noted. Although doxycycline exposure may add to that risk, taking the antibiotic does not necessarily mean pregnancy loss will occur. The available data suggests that it is just one risk factor among many.

Because doxycycline may be prescribed before a pregnancy is recognized, doctors should consider the possibility of pregnancy when prescribing this drug to women of reproductive age, particularly those who are sexually active, Grzeskowiak suggested. That does not mean doctors should avoid prescribing the antibiotic to these women, he emphasized; rather, clinicians should consider pregnancy plans and medical history when choosing a treatment.

In some cases, doxycycline may still be the best option for a severe infection, Winterstein told Live Science, and that infection could itself put a pregnancy at risk. But for less-serious infections, safer alternatives may be available, she said.

This article is for informational purposes only and is not meant to offer medical advice.

'> A widely used antibiotic for acne and infections is linked to risk of pregnancy loss, new study finds

"At 125,000 years old, these would be substantially older than the poisoned arrowheads recently identified in South Africa, which date to around 60,000 years ago," study co-author Chris Clarkson, an archaeologist at the Max Planck Institute of Geoanthropology in Germany and Griffith University in Australia, told Live Science in an email. "But we haven't demonstrated exactly how the poison was prepared or whether it was effective. So I'd describe these as potentially the oldest evidence for poisoned hunting weapons, rather than an unequivocally established first."

In the new study, published Thursday (Nov. 12) in the journal Science, researchers investigated a 125,000-year-old site in southern Saudi Arabia known as 'Uruq Aljelibah, which means "sand dunes of a watering hole," study co-author Frans van Buchem, a geologist at the King Abdullah University of Science and Technology in Saudi Arabia, told Live Science.

Today, the area is "hot, extremely dry, with extensive sand dunes," Clarkson said, located as it is within the Empty Quarter — one of the hottest, driest deserts on Earth. But the scientists found the site was once home to a freshwater lake measuring about 130 square miles (340 square kilometers) and up to 95 feet (29 meters) deep. Fossils there suggest it once supported a rich diversity of flora and fauna, including hippopotamuses, buffalo, ostriches, camels, gazelles, oryx, palms, reeds, trees and shrubs, which early modern humans likely exploited for food and other resources.

"The idea of hippopotamuses and enormous buffalo living around a lake in what is now the Empty Quarter really brings home just how dramatically these landscapes, and global climates, have changed," Clarkson said.

Astonishing stone tools

The archaeologists discovered more than 5,500 stone artifacts at the site, along with extraordinarily preserved traces of plant materials, such as fibers, resins and wood. Several of these artifacts were stone points that showed impact damage consistent with hunting large animals, and a microscopic analysis revealed traces of animal tissue near the point tips. The distribution of the stone tools closely matched clusters of animal bones, suggesting that the lakeshore was a focal point for hunting and processing game, according to the study.

"At most Paleolithic sites, we're lucky if we get the stone tools and perhaps a few animal bones," Clarkson said. "Here we can actually begin to reconstruct what those tools were doing and what other materials people were combining with them."

The researchers found that people may have hunted animals with poison-tipped tools. Several stone points had chemical residues linked with the arrow poison tree (Acokanthera schimperi), which is known historically for its toxins and is native to eastern and central Africa and southern Arabia. African hunters have coated spear tips and arrowheads with extracts from this plant to paralyze or kill game.

It remains unclear how hunters who poisoned their targets might have avoided poisoning themselves upon eating the game.

"The effects of a poison depend on the substance, the dose and how it enters the body," Clarkson said. "A poison introduced directly into a wound doesn't necessarily behave in the same way when swallowed." Hunters throughout history "are known to sometimes remove the meat around the wound before eating the rest of the animal," he added.

These findings emphasize how researchers have often underestimated the technological complexity of early human populations, because so much of what they made was organic and has simply disappeared," Clarkson said. "These weren't just people knocking stone flakes off cores," Clarkson noted. "They were combining stone with wood, plant fibers, resins and potentially toxic substances to make complex tools and weapons."

To have so much evidence for how people were making and using tools in a site like this "is remarkable," Eleanor Scerri, an archaeologist at the Max Planck Institute of Geoanthropology in Germany who did not take part in this research, told Live Science in an email. "This goes from both the micro-scale, in finding traces of how people hafted spear tips, for instance, up to the bigger scale of the whole site and the very convincing spatial relationship between hunting-related tools and the bones of animals such as hippos."

Sites in Arabia that possess both stone tools and animal bones are rare, Jeffrey Rose, a Paleolithic archaeologist at the University of Algarve in Portugal who did not participate in this study, told Live Science in an email. "This one has thousands of artifacts on an old lakeshore alongside hippo, buffalo and ostrich, and some of the flakes fit back together, so the tools were made on the spot," he said. "It's valuable new data."

Out of Africa

The Arabian Peninsula sits between Africa and the rest of Asia and was a major corridor for humans as they dispersed across the world. Recurring spans of increased rainfall could have made its otherwise hostile landscapes more habitable in the past. However, the hot desert that now covers much of Arabia has made it difficult for scientists to excavate many details about this vital bridge during this critical point in human history.

The researchers did not unearth any human remains. Still, they suspect the site most likely belonged to modern humans (our species, Homo sapiens), as opposed to a different human species.

"We know that H. sapiens had already expanded out of Africa and were present in Southwest Asia during this period," Clarkson said. "The age of the site fits with those early movements."

These findings add to growing evidence that wetter intervals in Arabia created migration corridors between Africa and Asia and supported productive habitats capable of sustaining repeated human occupation.

"What our site shows is that people weren't necessarily just passing through these environments," Clarkson said. "They were exploiting them in quite sophisticated ways, using a range of technologies and resources."

But Rose cautioned that all of the stone artifacts found in this study were collected from the surface. "Not one was excavated from the layers that were dated," he said. "The 125,000-year date belongs to the lake, not to the tools. For the tools, it is only a maximum age." Future research at the site should look for stone artifacts sealed in lake beds. "That's hard in Arabia, where wind has stripped most sites down to surface scatters, but it can be done," Rose said.

Clarkson agrees that further work is needed. "I'd really like to keep going back to this site to find more fossils, both animals as well as hopefully human fossils," Clarkson said. "I'd also really like to push the chemical and functional analyses further, particularly the evidence for toxic plant compounds. It would be fascinating to determine exactly which substances were being used, how they might have been prepared and whether they were deliberately applied to hunting weapons."

Future research focusing on the ancient lake margins may reveal more information. "There must be other places where people were living and carrying out activities, and some may preserve better stratified archaeological deposits," Clarkson said.

But the combination of discoveries at this site is amazing, the researchers said.

"I've spent much of my career studying stone tools, and one of the great frustrations is that we're usually only looking at the small fraction of ancient technology that survives," Clarkson said. "Here we have a chance to see much more of the complete technological system."

'> 125,000-year-old poisoned stone points discovered on shore of ancient lake in Saudi Arabia

Each year, about 10,000 babies in the United States are born with critical heart defects that may require surgery to fix, often fairly soon after birth. In these infants, the two major arteries of the heart could have swapped positions or the left side of the heart may be far too small to pump properly.

Even if their surgeries go well, these babies face perilous recoveries. A complication can arise when blood flows back into the repaired heart, triggering what's known as an ischemia-reperfusion injury. This can stun the organ, triggering extensive damage that requires doctors to place the baby on a life-support machine that pumps and infuses oxygen into blood to sub in for the hampered heart and lungs. Only about 40% of newborns make it off the machine, because often, their tiny hearts don't recover.

Doctors and scientists at Boston Children's Hospital have been working to improve those odds using a creative idea: replacing the fuel source in damaged heart cells to help them bounce back from injury. That fuel source is mitochondria, the "batteries" found in most cells in the body. In this case, the mitochondria are isolated from an abdominal muscle and then injected directly into the heart.

As of April, 17 babies have undergone this procedure, and 80% made it off ECMO. It's too soon to say if the treatment improves overall survival rates, but the early data hints that it might. A clinical trial is currently underway.

"The first one or two for me were pretty nerve-wracking," said James McCully, a research associate at Boston Children's Hospital and associate professor of surgery at Harvard Medical School whose pioneering work paved the way for these procedures. His team isolates and purifies the mitochondria that a surgical team then transplants into patients.

"But you know, the heart comes back — you can actually almost see it coming back" in real time, he told Live Science. A heart deprived of energy looks pallid, while a freshly rejuvenated heart blushes a healthy pink.

Baby heart infusions are just one example of the promise of "mitochondrial transplantation." Following McCully's lead, other scientists have started investigating whether infusions of mitochondria could revitalize donated organs destined for transplantation, help stroke patients recover, and treat kids with devastating diseases. This work is still highly experimental, and its route to regulatory approval remains unclear.

But at its core is a straightforward idea: When a battery dies, you replace it.

Relic of our evolutionary past

The human body contains tens of trillions of cells, most of which contain hundreds to thousands of mitochondria. Following some back-of-the-envelope math, that means the total potential energy in each person "is the equivalent of a lightning bolt," Douglas Wallace, director of the Center for Mitochondrial and Epigenomic Medicine at Children's Hospital of Philadelphia, told attendees last year at a symposium on mitochondrial medicine.

Mitochondria, in a word, are powerful. They produce most of the chemical energy used by complex cells by churning out a molecule called adenosine triphosphate (ATP). The idea of transferring these fuel factories from one cell to another as a medical treatment emerged less than two decades ago — but cells have been doing such swaps on their own for eons.

Dr. Jon Brestoff, an associate professor of pathology and immunology and director of the Immunometabolism Initiative at the Washington University School of Medicine in St. Louis, describes this ability to move from cell to cell as a relic of mitochondria's bacterial past. "It is hypothesized that mitochondria transfer has likely been retained throughout evolution of eukaryotic life," the huge domain of life that includes all plants, fungi, protists and animals, Brestoff told Live Science.

Mitochondria are the powerhouses of nearly all complex cells on Earth, and there are a few theories as to how they adopted that ubiquitous role. A leading idea posits that, some 1.5 billion to 2 billion years ago, one simple cell engulfed another. The bacterial cell that got swallowed carried a circular loop of DNA inside its membrane, and that captured cell later became what we now know as the mitochondrion. The new organelle enabled cells to take advantage of the abundance of oxygen on our planet by converting it into usable fuel.

Mitochondria retained bacteria-like features, such as having their own DNA and membranes. But in 2006, researchers reported that mitochondria can also exit their "host" and survive the journey into a totally different cell — a phenomenon known as mitochondrial transfer.

"That was a complete revolution in thinking," said Dr. Lance Becker, professor and Chair of the Department of Emergency Medicine at Northwell Health and the Feinstein Institutes for Medical Research. "With that notion that mitochondria might be mobile, that they might cross boundaries, that they might go from one cell to another cell, came the possibility that maybe that was something we could use to help people."

The 2006 study showed that cells that had been depleted of their own mitochondrial DNA could obtain healthy mitochondria from neighboring cells. After receiving other cells' powerhouses, the once-depleted cells were able to conduct energetically costly processes, such as cell division.

This research provided the first evidence that one cell can "donate" metabolic properties to its neighbor by sending over a fresh batch of mitochondria. Scientists once thought cells had to make all of their own mitochondria, but now, "I think cells have the ability to 'put their hand up' when they need mitochondria," Becker told Live Science.

Because those first experiments were done in lab dishes, initially, "it was unclear whether or not it was really biologically meaningful or relevant," Brestoff said. But within the past five to six years, improved tools and techniques have enabled scientists to watch mitochondrial transfer unfold within living organisms, he noted. It's been shown that cells of the same type can exchange mitochondria, as can cells of different types.

As scientists' fundamental understanding of mitochondrial transfer grew, the notion of doing the same thing therapeutically gained more traction.

"That procedure," Brestoff said, "is rooted in the biology of mitochondria transfer."

"The heart came back"

Just two years after the landmark 2006 paper, McCully's research group released data that hinted at the medicinal potential of mitochondrial transplantation.

Since then, these complementary lines of research — the foundational biology and the preclinical investigation — have continued in parallel. McCully's preclinical work helped to inspire other labs to explore the use of mitochondrial transplantation for a range of medical applications, including organ transplants and treatments for stroke and genetic disease.

McCully is "the pioneer — the guru of the field," said Dr. Giuseppe Orlando, a professor of surgery and regenerative medicine at Wake Forest University School of Medicine who is exploring mitochondrial transplantation as a way to maintain the integrity of transplant organs.

McCully's road to mitochondrial transplantation started in the 1980s. As a molecular biologist, he wanted to uncover mechanisms that protect the heart from damage, particularly when the organ's oxygen supply is compromised — such as during ischemia, or low blood flow. With an eye on older adults, he wanted to spare patients' heart tissue from the damage and cell death that can occur before and during heart surgery.

McCully and his collaborators initially "didn't care about the mitochondria one iota," he said. They were more focused on the nucleus, the control center that houses most of a cell's DNA, and its influence on cellular pathways that might boost the heart's resilience to ischemia. But "what we found was that everything we did started coming back to the mitochondria," he said.

They found that ischemia triggers damage and dysfunction in mitochondria that persists even after the heart's oxygen supply is restored; this dysfunction ultimately kills cells. The damaged mitochondria swell up, leak their innards, and set off a chain reaction that causes a cell to self-destruct.

McCully and colleagues observed that biological pathways that seemed to reduce this cell death often centered on the mitochondria. "We were looking around at either pathways upstream of the mitochondria or downstream of the mitochondria," he said.

So, logically, they started looking directly at mitochondria, studying what the organelle looks like before, during and after ischemia. One day, while isolating mitochondria from a laboratory pig, the animal developed fibrillation, meaning its heart began beating very quickly, with an uncoordinated and rapid rhythm. The team tried to reset the heart's rhythm with electric shocks and medications, to no avail. But McCully had an idea.

"At that point in time, the heart's kind of [got a] gray pallor, and it looks dead," he said. "And I said, 'Go upstairs; grab some of those mitochondria that we've isolated from the non-ischemic type. Just bring them down.'" They'd previously gathered some healthy mitochondria from the same pig, in hopes of generating a "before-and-after" picture of ischemia. Instead, McCully suspended those healthy mitochondria in a solution and then injected them directly into the pig's fibrillating heart.

"And the heart came back — started beating normally. It changed color, went back to a pink hue, and just kept on going," he said.

That serendipitous experiment led to a formal test of the technique in rabbit hearts, the results of which were published in 2008. In the study, they introduced healthy mitochondria to the rabbits' hearts during ischemia, just before reperfusion — when blood is reintroduced into the oxygen-starved tissue. They found that the mitochondria improved the organs' recovery and reduced tissue death. Further research in animals suggested that mitochondria that originated from one type of tissue, like liver tissue or skeletal muscle, could be introduced to other tissue types, such as cardiac muscle.

After seeing McCully's results in various animal experiments, including more with pigs, Dr. Pedro del Nido, chair of cardiac surgery at Boston Children's and a professor of child surgery at Harvard Medical School, approached him about testing the technique in human patients — namely, in babies on a life-support machine known as ECMO.

"He saw it in the animals; he saw what was going on," McCully said. "And he deemed it as being a possible intervention to save these kids."

They sought permission from the Food and Drug Administration (FDA) to test the procedure and cleared the required regulatory hurdles. The process was made slightly easier because the mitochondria were coming from the patients' own bodies, not from a donor, McCully noted. Once given the go-ahead, they set forth with the help of Dr. Sitaram Emani, a heart surgeon at Boston Children's. The first procedure took place in 2014.

During each procedure, Emani and the surgical team collect a small sample of skeletal muscle from the patient, and McCully then isolates whole mitochondria from the tissue and prepares them in a syringe. He refined the isolation technique so the time from collecting the muscle sample to injecting mitochondria is only 30 minutes. Lately, the team has been developing a technique they can perform in the operating room, rather than in a lab, which could cut the time to 20 minutes. Emani uses various tests, including echocardiography, to see which areas of the heart tissue move the least, and injects mitochondria straight into those areas.

"It's great to be able to see something you've done and worked on for so many years actually provide a benefit," McCully said.

Transplants for transplant organs

While McCully is trying to protect infant hearts, other scientists want to do the same for other organs — including those destined for transplant surgeries.

To Orlando, mitochondria represent a potential way to make donated kidneys work better. "In transplant medicine, one of the major issues is making sure that the organs that are procured are well stored and kept viable until implantation," said Orlando, who is also president of the Cell Transplant and Regenerative Medicine Society.

Maintaining an organ's viability means preserving mitochondrial function as much as possible, but the transplantation process is tough on the organelles. "That energy plant is damaged. So it's pretty obvious that you should start thinking about a way to replace the damaged mitochondria," Orlando said.

Donated organs suffer some damage when they're unplugged from the donors' bloodstream, in part because this cuts off mitochondria's crucial oxygen supply. And then, paradoxically, the donor organs also get damaged when they're plugged into the recipient's bloodstream. That's because the fast flow of blood triggers the production of free radicals — unstable molecules that damage tissues.

While healthy organs normally produce some free radicals, reperfusion unleashes a flood. "It's more than the organ can bear and sustain," Orlando explained. This damage contributes to a phenomenon called delayed graft function, in which a transplanted kidney doesn't work right away so the patient ends up needing dialysis in the first week after surgery.

"You want to make sure that the kidney wakes up faster," Orlando said. That's where mitochondria come in.

Orlando was introduced to the idea of mitochondrial transplantation around 2019 through a collaboration with Dr. Benedetta Bussolati, a nephrologist and full professor of laboratory medicine at the University of Turin in Italy. Her lab had been studying mitochondrial transplantation in isolated kidney cells in lab experiments, and they reached out to Orlando about extending that work to lab animals.

In pigs, the researchers ran experiments in which the animals' kidneys were collected and stored in the same way human kidneys commonly would be prior to being transplanted. One set of kidneys received a placebo treatment, while another got an infusion of mitochondria from the donor pigs' muscle tissue. Upon being reperfused, the treated kidneys produced fewer free radicals and accrued less damage than the untreated kidneys did, the team reported in 2023.

They backed up this finding by analyzing RNA, a molecule that reflects which genes are active in cells. Compared with the untreated kidneys, the treated kidneys showed greater activity in genes involved in mitochondrial metabolism and lower activity in genes involved in repairing injuries.

Some groups are exploring mitochondrial transplantation in other donor organs, like the lungs — specifically, lungs treated with "ex vivo perfusion" (EVP), an emerging approach that helps retain the viability of transplant organs. Rather than placing a donor organ in a cooler of ice, as is generally standard, EVP flushes an organ with nutrient- and oxygen-rich fluid, helping to maintain its function until the transplant surgery. In lab experiments with pig and human lungs, scientists found that introducing fresh mitochondria during EVP further improved the organs' function while reducing inflammation and free radicals.

Across different organ transplants, Orlando sees mitochondria as a potential means to improve patient outcomes and expand the pool of available organs. There are scenarios in which would-be organ donors die unexpectedly of cardiac arrest and their organs are damaged in the process; mitochondrial transplants may help make such organs fit for patients, Orlando has said.

In the near term, Orlando and his colleagues are continuing to study the basic science of mitochondrial transplantation for this clinical purpose; they've also been cleared to run a clinical trial with donor kidneys but need more funds to proceed.

Looking to the more distant future, he and other experts in the field envision a world where transplant organs can be bioengineered and stored in banks, ready and waiting for the patients who need them, Orlando said. If that vision materializes, he suggested, mitochondrial transplants might be useful for preparing banked organs for transplantation "by giving them kind of an energy boost."

Reaching the brain

If infusions of fresh mitochondria could help the heart, kidney and lungs, what about the brain? That's the question Dr. Melanie Walker and colleagues at the University of Washington School of Medicine (UW Medicine) want to answer.

Walker, a clinical professor of neurological surgery, treats patients who have had ischemic strokes, which are caused by blood clots blocking blood flow to the brain. The immediate aim of post-stroke treatment is to clear out the blocked "pipe" and restore circulation to the brain as quickly as possible, she said. But no matter how quickly this is done, some brain cells are damaged. And once the blood clot is removed, the brain may then suffer a reperfusion injury.

Standard treatments can dissolve the clot but don't protect the brain, Walker said. "What about all those cells that are maybe not quite dead — they're on the verge of maybe dying? What can we do to support those guys?" she asked.

The UW Medicine team had heard about McCully's work in Boston and wondered if something similar could be applied in stroke patients. But while heart surgery exposes the tissue in need of new mitochondria, accessing the brain is trickier. "You don't do a craniotomy to give an IV medicine," Walker told Live Science.

But Walker realized that a harmful downstream effect of stroke might provide an opportunity for treatment. Immediately after a stroke, the brain's protective shield — known as the blood-brain barrier — becomes more permeable than usual, allowing more substances to pass from the bloodstream into brain tissue. That might open a door for mitochondrial transplantation.

A 2023 mouse study spearheaded by University of Virginia researchers and co-authored by Walker backed this idea, finding that mitochondria entered the brain after stroke and integrated into brain cells. These mitochondria had been gathered from muscle tissue, as in McCully's studies, and introduced to the brain via an artery. The treatment increased ATP production while reducing cell death caused by the stroke, compared with untreated mice's brains.

This work paved the way to the first trial using mitochondrial transplant in the human brain. The small safety trial included adult patients who'd had ischemic strokes and underwent thrombectomies ‪—‬ surgeries to remove the clots from their blood vessels. Four received mitochondrial transplants during their procedures and 12 did not. Mitochondria were injected near the site of each patient's stroke, into the closest branch of one of the brain's major arteries.

No negative side effects were tied to the transplants, hinting that the procedure is safe in humans. "But the next question is, how do we understand if it helps? And those are harder trials to design," Walker said. That's partly because the transplants are tacked onto the clot-removal procedure, so it's difficult to separate their effects from those of the clot removal itself, she noted.

Future trials will also need to explore exactly where the transplanted mitochondria end up in the human brain, how well they function once inside brain cells, and how the dose and timing of the transplant affect patients' outcomes, the trial runners wrote in their report. For the moment, Walker said her team is focused on exploring the safety aspects of the approach and have no further trials planned at this time.

Mitochondrial diseases — and what's next

Beyond heart defects, transplant organs and stroke, researchers are looking to mitochondrial transplantation as a solution for genetic conditions that harm mitochondria directly. Brestoff and colleagues are investigating the therapy's potential for treating Leigh syndrome, a rare neurological condition caused by genetic mutations that disrupt the fuel-producing machinery in mitochondria.

"Those kids have a terrible prognosis," Brestoff said. Most children with the most common form of the syndrome, whose symptoms show up by age 2, die by age 3. There is no cure for the syndrome, and treatments to relieve its symptoms are limited. So if it works, mitochondrial transplantation could fill a big gap.

So far, the approach shows promise in lab mice with a severe form of Leigh syndrome, improving the rodents' function and extending their median lifespan by 19% to 24%, the researchers demonstrated in 2024. They're now studying the approach in cells derived from patients with the disease.

Some companies, such as Israel-headquartered Minovia Therapeutics, are already running clinical trials with patients with other types of mitochondrial disease. Minovia is running one with children with Pearson syndrome, in which missing mitochondrial DNA hinders the function of bone marrow, which normally makes blood and immune cells.

While patients with a heart or brain problem may be able to pluck mitochondria from healthy muscles, people with mitochondrial disease don't necessarily have healthy mitochondria to spare. Especially for these patients, getting mitochondria from other people ‪—‬ known as heterologous transplantation ‪—‬ likely makes the most sense. What's more, for transplantation to be used widely for any purpose, there would need to be an "off-the-shelf" mitochondrial product available, Brestoff said.

Such a product could eliminate the step in Boston Children's heart procedure where mitochondria have to be isolated from a patient while they're waiting, open on an operating table. "Getting them from the recipient can sometimes be problematic, because the recipients are sick. All the organs, all the tissue is quite distressed," McCully noted. A standardized and safety-tested mitochondrial product would therefore be a boon for the field.

Brestoff is on the scientific advisory board of LUCA Science, a company developing mitochondria as therapeutic agents, and a consultant for Cellergy Therapeutics, which is making mitochondrial products to combat conditions from muscle degeneration and aging. These companies exemplify the effort to come up with ready-made products that could someday bring the therapy to more patients.

A shift to heterologous transplantation does raise concerns about immune reactions. "You have some variations in the proteins that are present in your mitochondria that I don't have," Brestoff noted. "So it is possible that our immune systems recognize heterologous mitochondria as non-self."

But McCully doesn't expect immune reactions to be a big problem, based on his research in animals. "I can get the mitochondria from you and put them into me, me into you — doesn't really matter," he said. Early trial results from Minovia and others suggest heterologous transplantations come with minimal side effects, at least at doses tested so far.

Another roadblock is that the FDA has not approved any organelles as therapies yet, so the standards and regulatory framework for the field are still being established, Brestoff said.

Despite that hurdle, the field has advanced significantly since its start as a niche, theoretical interest and then a highly experimental procedure for the sickest newborns. Scientists are now exploring the treatment as a solution to many common conditions, from rheumatoid arthritis to chronic pain.

Becker compared the state of the field to the early days of organ transplantation.

"It just turned out that it was revolutionary, when all of a sudden you could just give a person a kidney transplant," he said. "I think it's going to be kind of similar with mitochondria."

This article is for informational purposes only and is not meant to offer medical advice.

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'> When a battery dies, you replace it — how jumpstarting cells with fresh mitochondria could revolutionize medicine statement. "This major Euclid data release represents the largest space-based survey of its kind, laying the foundation of future discovery."

Captured over 13 months, this cornucopia of data covers a slice of sky about 9,500 bigger than the full moon — about 14% of the total sky area that Euclid will survey on its planned six-year mission. Each object in the survey is like a "puzzle piece," with its specific light signature, or spectrum), offering clues about its composition and distance from Earth, according to ESA.

Scientists can now start using the 1.7 million gigabytes of Euclid data to slot those objects into a 3D model of the universe and begin to map out the vast cosmic web that underlies all galaxies. But the data release also includes some stunning space images, which you can enjoy immediately. Here are some of the highlights.

A record haul of "Einstein rings"

Gravitational lenses are nature's biggest magnifying glasses. These "Einstein rings" ‪—‬ named after Albert Einstein, who predicted their existence — occur when exceptionally massive objects, like large galaxies, bend the fabric of space-time. This cosmic curvature causes the light emitted by objects behind them to appear magnified, distorted and sometimes duplicated.

In its first data release, Euclid has discovered more than 15,000 strong gravitational lensing candidates. These cosmic lenses enable astronomers to get much clearer views of the deep universe than any telescope could possibly see on its own.

"Over 10 years ago, we forecast that Euclid would revolutionise the field of strong lens discovery," Natalie Lines, a Euclid Consortium member working at the University of Portsmouth in the UK, said in the statement. "That day is finally here."

Grand design

The Messier 81 galaxy (seen on the right) is one of the brightest in the sky. With fully developed spiral arms stretching to its bright core, M81 is known as a "grand design spiral" galaxy.

While M81 is relatively close to Earth and can be seen with a good pair of binoculars, Euclid's field of view captures it alongside the elliptical galaxy NGC 3077 (bottom left) and crisp clouds of interstellar dust.

Golden Eye

Among the nearly 1 billion galaxies charted by Euclid is NGC 1291, also called the Golden Eye galaxy. The galaxy is located 33 million light-years from Earth, and Euclid shows a close-up view of it here at the telescope's highest resolution, according to ESA.

Ring galaxies like this contain a central bulge disconnected from a surrounding ring of stars; astronomers think these galaxies form when a smaller galaxy plunges through the middle of a larger one.

Filling the map

This image shows the entire sector of the Euclid Wide Survey, the telescope's mission to map vast swatches of the northern sky. The Wide Survey is accompanied by the Euclid Deep Survey, which will spend about 10% of the telescope's observing time taking repeated observations of three relatively small spots of sky, according to ESA.

With about 85% of its survey left to go, Euclid is on track to collect one of the most comprehensive datasets of the universe ever. Now, it'll be up to the scientific community to make good use of those observations and find something extraordinary.

For more stunning space images, check out our Space Photo of the Week.

'> Euclid space telescope unveils first major data release, including map of 900 million galaxies