The torch relay for the 19th Asian Games kicked off near the iconic West Lake in Hangzhou, East China's Zhejiang Province on Friday.
Swimming great Luo Xuejuan, the women's 100 meters breaststroke winner at the 2004 Athens Olympic Games, was the first of the 106 torchbearers during the opening-day relay.
Back in 2008, Luo was also the first Chinese bearer to carry the Olympic torch for the Beijing Games during the flame-lighting ceremony in Greece.
"I was very excited," the Hangzhou local recalled about her feelings when Hangzhou won the bid for the Asian Games eight years ago. "We just wanted to invite guests from all over the world to come and see, and today it finally came true."
"Actually, I only found out a few days ago that I would be the first torchbearer for the Asian Games, and I was very pleasantly surprised," she told reporters on Friday.
"I just feel honored. In fact, when I stood on the starting point, I was not just representing myself, I was representing the athletes, and the more than 12 million Hangzhou people."
Other high-profile bearers on the first day included Olympic champion volleyball star Hui Ruoqi, Olympic champion shooter Yang Qian, etc.
According to organizers, a total of 2,022 torchbearers will participate in the 13-day relay, ranging in age from 14 to 84. Among them, there are 732 women, 1,219 grassroots front-line representatives, 1,069 advanced role model representatives, and 275 sports worker representatives. In addition, there are a certain number of representatives of ethnic minorities, representatives of Hong Kong, Macao and Taiwan compatriots, and representatives of the disabled.
The torch will journey through 11 cities across Zhejiang, including Huzhou, Jiaxing, Shaoxing, Ningbo, Zhoushan, Taizhou, Wenzhou, Lishui, Jinhua, and Quzhou, before returning to host city Hangzhou on September 20 to complete its final leg. The opening ceremony of the Asian Games will be held on September 23.
The torch relay also incorporates online and offline elements. The online relay activity of the "Digital Torchbearer" was launched after the Asian Games flame collection ceremony on June 15. So far, more than 84 million people have participated in the Asian Games online torch relay.
The torch of the Hangzhou Asian Games is named "Eternal Flame," whose design was inspired by the Liangzhu Culture that is testament to the 5,000-year-old Chinese civilization. The Hangzhou Asian Games flame was lit at the Liangzhu ancient city in Zhejiang on June 15 - 100 days before the opening of the Games. Listed as a UNESCO World Heritage site in 2019, the Archaeological Ruins of Liangzhu is a sacred place that has born witness to over 5,000 years of Chinese civilization.
In the science fiction movie "The Wandering Earth," artificial intelligence system "Moss" is able to explore all solutions to save the Earth in just a few seconds.
This miraculous scene is gradually transitioning from science fiction to reality. The ultra-high-performance optoelectronic chip proposed by the research team at Tsinghua University adopts a new architecture of optoelectronic fusion, which is disruptive to existing chip technologies, the team told the Global Times on Wednesday.
The technology not only opens up a new path for this future technology to become part of daily life, but also provides inspiration for the integration of other future high-performance technologies such as quantum computing and in-memory computing with current electronic information systems.
The results, titled "Purely Analog Optoelectronic Chips for High-Speed Visual Tasks," had been published in the recent issue of the journal "Nature."
In 1965, Gordon Moore, one of the founders of Intel, proposed "Moore's Law," which has influenced the chip industry for over half a century. It predicts that the number of transistors on integrated circuits will double approximately every two years.
The semiconductor field has prospered for decades based on Moore's Law, and "chips" have become an important engine for humanity's entry into the era of digital intelligence. However, as transistor sizes approach their physical limits, Moore's Law has slowed down or even faced failure in the past decade. How to build a new generation of computing architecture and establish a "new" order of chips in the era of artificial intelligence has been a frontier hotspot of international concern.
To address this challenge, a joint research team from Tsinghua University, including Academician Dai Qionghai from the Department of Automation, Assistant Professor Wu Jiamin, Associate Professor Fang Lu from the Department of Electronic Engineering, and Associate Researcher Qiao Fei, proposed a new computing architecture that "breaks free" from Moore's Law: optoelectronic analog chips. In practical tests for visual tasks, the computing power of these chips reached over 3,000 times that of current high-performance commercial chips.
From a physical perspective, optoelectronic chips are based on a disruptive technology that is different from existing chip technologies, the research team explained in an interview with the Global Times on Wednesday. They noted that, at current stage, their work is focused on intelligent visual tasks, and they are also conducting further exploration to see if the new technology can achieve tasks of the same or even higher complexity as current chips, such as large language models.
In this small chip, the Tsinghua University research team creatively proposed an optoelectronic deep fusion computing framework. Starting from the most fundamental physical principles, it combines optical computing based on electromagnetic wave propagation in space with pure analog electronic computing based on Kirchhoff's law. It "breaks free" from the physical bottlenecks of data conversion speed, accuracy, and power consumption that constrain traditional chip architectures, and overcomes three international challenges: large-scale computing unit integration, efficient nonlinearity, and high-speed optoelectronic interfaces.
In the demonstrated intelligent visual scene tests in the paper, the system-level computing power of the optoelectronic fusion chip was thousands of times higher than that of existing high-performance chip architectures. However, such astonishing computing power is just one of the many advantages of this chip. In the intelligent visual tasks and traffic scene calculations demonstrated by the research team, the system-level energy efficiency (the number of operations that can be performed per unit of energy) of the optoelectronic fusion chip reached 74.8 Peta-OPS/W, which is over 4 million times that of current high-performance chips. In other words, the amount of electricity that can power existing chips for one hour can power this chip for over 500 years.
One key factor currently limiting chip integration limits is the heat dissipation problem caused by high density. The optoelectronic fusion chip, which operates at ultra-low power consumption, will greatly improve the chip's heat dissipation problem and bring all-round breakthroughs to the future chip design. Furthermore, the minimum linewidth of the chip's optical part is only in the hundreds of nanometers, while the circuit part uses 180 nanometers Complementary metal-oxide-semiconductor technology, achieving a performance improvement of multiple orders of magnitude compared to 7 nanometers process high-performance chips. At the same time, the materials used are simple and easily obtainable, and the cost is only a fraction of the latter.
Will the emergence of this cutting-edge chip technology help China achieve a "overtaking on the curve" in chip research and development? In response to this question, the research team told the Global Times that the research and development competition in the traditional chip technology field is becoming increasingly fierce, and facing international challenges such as the slowing down of Moore's Law, the world is seeking new computing architectures. It can indeed be understood as a kind of "curve" opportunity. Whether we can achieve "curve overtaking" depends on the joint efforts and ecological construction of all sectors. We are also working towards this goal.
A special review of this research, invited by the journal Nature, pointed out that the appearance of this chip may allow the new generation of computing architecture which will be integrated into daily life much earlier than expected. Academician Dai Qionghai, one of the corresponding authors of the paper, stated, "Developing a new computing architecture for the era of artificial intelligence is a summit, but truly implementing the new architecture in real life to solve major national and livelihood needs is a more important challenge and our responsibility."
Airbus is playing a role of "catalyst" in Chinese market for the development of sustainable aviation fuel (SAF) industry, propelling sustainable energy transition in civilian aviation sector to realize decarbonization targets, an executive from Airbus said in Beijing on Tuesday.
Airbus is working on a number of levers, so the first one is technology and fleet renewal. The company is also working actively on improving the efficiency of operations. And the third and very big one is the energy transition of which SAF is a key topic, Julie-Kitcher, Executive Vice President of Airbus said.
The comments are made as more Chinese airlines vowing to promote use of sustainable aviation fuel. In October of last year, Airbus said its Tianjin plant delivered an A320neo to China Eastern Airlines that used five percent SAF as the fuel during its delivery flight.
SAF is a sustainable aviation fuel made from feedstock ranging from used fat, oil and grease to municipal and forestry waste. Compared to fossil jet fuel, SAF has been demonstrated to result in an up to 80 percent reduction in CO2 emissions. Therefore, it is considered as a key enabler to contribute to the de-carbonization of aviation sector. And so when talking about SAF, there's a huge capability in China with feedstock in abundance, technology and innovation and in fact, China has been supporting certification since 2008 in different ways. All the airlines have expressed interest in environmental matters on sustainability, SAF in particular, Kitcher said.
And Airbus is working with China National Aviation Fuel Group Corporation to develop the SAF industry or act as a catalyst in China, she added.
In July of last year, the Airbus Lifecycle Services Center project broke ground in Chengdu, Southwest China's Sichuan Province. The project is Airbus' first aircraft lifecycle service project outside Europe. The company said the project has moved from the planning stage to construction and the aim is for it to enter into service by the end of 2023.
Airbus is spending around 2 billion euros per annum on R&D, which is mainly targeting sustainable aviation. All partners and players will need to make significant investments for their respective licenses to continue to operate. Aircraft manufacturer need to really look at the overall lifecycle of the aircraft, so it's from design, supply chain, the operations, the maintenance, and the end of life recycling, Kitcher said.
To show the conviction in terms of the necessity to decarbonize the sector, Kitcher said that they're working on different levels for the industry, including the technology starting with fleet renewal and enhancing and improving the efficiency of air traffic management operations.
She also said to enhance the energy transition, which means to increase the adoption of SAF, Airbus targets to certify all its aircraft with 100 percent SAF capability by the end of this decade, adding that the company is also developing hydrogen technologies for future use.
Airbus is aiming to reach a global 10 percent target by 2030, which is around 34 million tons of SAF by 2030.Actual demand for probably around 20 million tons are committed. So "we still have progress to make, but we're confident that collectively we can get there", she said.
For the first time in the United States, free-flying genetically modified mosquitoes have federal approval to take wing in Florida. But when, and if, that will happen is still up in the air. Local officials will make the final decision — possibly not until after the November elections.
The World Health Organization has recognized these mosquitoes as possible tools for fighting the spread of mosquito-borne Zika virus. But the U.S. Food and Drug Administration’s decision, announced August 5, covers only a specific, preliminary test release of GM mosquitoes on Key Haven in the Florida Keys, where no locally transmitted Zika cases have been reported. This trial of OX513A mosquitoes, genetically engineered by the British company Oxitec, “would be unlikely to result in adverse effects on the environment or human health,” the FDA ruled. If Key West commissioners approve it, the trial would release abundant GM male Aedes aegypti species carrying a gene that will cause their offspring to die. In tests in Brazil, Panama and the Cayman Islands, months of releasing these mosquitoes has reduced the wild populations of Ae. aegypti mosquitoes by 90 percent or more. As a result, a Brazil neighborhood has seen mosquito-borne dengue cases plummet (SNOnline: 7/15/16).
To see whether OX513A could work in the United States, too, the test release would now need approval from the Florida Keys Mosquito Control District Board of Commissioners. Opponents of GM organisms have protested the idea, so the five commissioners have arranged for a nonbinding referendum question to appear on the November ballot. Commissioners plan to wait until the community has weighed in before making their final decision, says mosquito control district spokeswoman Beth Ranson.
If the mosquito plan gets a thumbs up, Oxitec could release mosquitoes in December, said Hadyn Parry, the company’s chief executive officer. Monitoring and testing could take six months and results would go back to the FDA with an application to allow the mosquitoes to be released commercially — and more broadly — in the United States for mosquito control.
As Zika rages in Puerto Rico, and with Miami reporting the first locally mosquito-transmitted cases on the U.S. mainland, debate over the controversial mosquito has taken on new urgency. Tom Frieden, director of the U.S. Centers for Disease Control and Prevention, has noted that efforts to eradicate mosquitoes in an area in Miami have fallen short (SNOnline: 8/1/16).
Ae. aegypti mosquitoes resist many pesticides, bite during the day, love human houses, and can breed in plant saucers and other small pools of water. Virtually a domestic animal, this species bites people almost exclusively. It’s suspected to be the main spreader of Zika virus, and also does a fine job of infecting people with dengue, chikungunya and yellow fever viruses. Oxitec GM mosquitoes, developed in 2002, would target Floridian pests via a new twist in the decades-old strategy of male sterilization. Mid-20th century entomologists sterilized screwworms by irradiating them and releasing the decoy males in overwhelming clouds. So many wild females mated with these sterile males that eventually the gruesome screwworm pests of livestock disappeared from the United States.
OX513A, with their mix of old-fashioned strategy and newfangled genetic tinkering, has kicked up anti-GMO feeling, even though it’s not the first U.S. approval of testing a GM insect in pest control. That honor goes to pink bollworms in the Southwest in 2009, though their release passed largely unnoticed outside the pest-control community. But when the FDA released a favorable draft opinion in March, saying the GM-mosquito test would probably have “no significant impact” on people or the environment, more than 2,000 people typed comments on the public FDA site. Many were vehemently opposed to the plan, peppering their comments with multiple exclamation points and the occasional “OMG!!!”
Some commenters worried about blood contact from the bite of a GM organism, possible allergies should someone accidentally swallow one and unknown consequences to the environment.
Oxitec posted explanations responding to those fears: Almost all mosquitoes released would be males, which don’t bite; males will die three or four days after release; their offspring are engineered to die without unnatural amounts of tetracycline — a lab-provided supplement — in their diets. Angry public comments, however, largely dismissed these reassurances as corporate-funded research.
Another commenter wondered whether a successful test, driving down the Ae. aegypti population on the Keys, could make room for some other insect menace. That’s a reasonable question, says Phil Lounibos of the University of Florida in Vero Beach. He has studied competition between Ae. aegypti and the relentlessly biting Asian tiger mosquito, Aedes albopictus. These tiger mosquitoes were once rare on the Keys, but he has found that they can take over from Ae. aegypti, in part by sexual deception. Tigers that mate with Ae. aegypti females render the females sterile and have thus conquered other parts of Florida. Even though Ae. aegypti is recognized as a more potent vector for human disease, the tigers can carry many of the same viruses (including Zika), Lounibos warns (SNOnline: 5/16/16).
As far as ecological concerns go, entomologist Bruce Tabashnik of the University of Arizona in Tucson, has no problem with eradicating Ae. aegypti from the Florida Keys or anywhere else in the Americas. “It’s an invasive species,” he says. “There are no ecological ethics violated.”
Tabashnik was part of the research team monitoring the first GM insect release in the United States: sterile male pink bollworms. Males of this invasive pest species that prey on cotton in the Southwest were sterilized by radiation. However, Oxitec had inserted a gene that made them fluoresce red so monitors could tell the friendlies from the wild targets. Tabashnik recalls no particular public outcry over the experiment. It took place in a sparsely populated area and, instead of mosquitoes, involved a kind of moth only a cotton farmer could hate.
So far outrage, or even interest, in other tweaked pest-control animals seems minimal compared with GM-mosquito fever. A proposed test of Oxitec’s GM diamondback moth in New York has inspired fewer comments. Tests of a non-GM but still tinkered-with mosquito — Ae. albopictus developed to carry Wolbachia bacteria that interfere with mating — were first approved in 2012 for release in American Samoa. Later tests have released these bacteria-carrying mosquitoes in California and other sites in the mainland United States.
Baby humans’ brain cells take awhile to get situated after birth, it turns out. A large group of young nerve cells moves into the frontal lobe during infants’ first few months of life, scientists report in the Oct. 7 Science. The mass migration might help explain how human babies’ brains remain so malleable for a window of time after birth.
Most of the brain’s nerve cells, or neurons, move to their places in the frontal lobe before birth. Then, as babies interact with the world, the neurons link together into circuits controlling learning, memory and social behavior. Those circuits are highly malleable in early infancy: Connections between neurons are formed and severed repeatedly. The arrival of new neurons during the first few months of life could help account for the circuits’ prolonged flexibility in babies, says study coauthor Eric Huang, a neuropathologist at the University of California, San Francisco. “The fact that [the neurons] are migrating for months and months is remarkable,” says Stephen Noctor, a neuroscientist at the University of California, Davis who wasn’t involved in the work.
Huang and colleagues noticed a group of cells making proteins related to migration when looking at slices of postmortem infant brains under an electron microscope. To catch these neurons in the act of moving, though, the team used rare samples of brain tissue collected and donated immediately after infants’ deaths. The team infected those tissues with a virus tagged with a glowing protein. When the virus infected the brain cells, they glowed green. Then the researchers could track the migrating neurons’ path across the brain. The neurons started as a cluster in the subventricular zone, a layer inside the brain where new neurons are born, and then formed a chain moving into the frontal lobe, Huang’s team found. Once the migrating neurons settled down later in development, they mostly became inhibitory interneurons. This type of neuron acts like a stoplight for other neurons, keeping signaling in check. Huang’s team found migrating neurons in the brains of babies up to about seven months old, with migration peaking around 1.5 months and then tapering off.
“In the first six months, that’s kind of [infants’] critical period when they slowly develop their response to [their] environment. They start to engage with emotions,” says Huang. “Our results provide a cellular basis for postnatal human brain development and how cognition might be developed.”
By replenishing the frontal lobe’s supply of building blocks midway through construction, the new neurons might help babies’ brain circuits stay malleable longer. The mass migration after birth means that experiences in infancy could affect where these neurons end up — and, by extension, the connections they form.
The finding raises additional questions about the timing of the event, Noctor says — like when the migrating cells were born and how long an individual cell takes to move.
SAN FRANCISCO — Having an extra chromosome may suppress cancer, as long as things don’t get stressful, a new study suggests. The finding may help scientists unravel a paradox: Cells with extra chromosomes grow slower than cells with the usual two copies of each chromosome, but cancer cells, which grow quickly, often have additional chromosomes. Researchers have thought that perhaps extra chromosomes and cancer-causing mutations team up to produce tumors.
Jason Sheltzer, a cell biologist at Cold Spring Harbor Laboratory in New York, and colleagues examined the effect of having an extra chromosome in mouse cells that also have cancer-promoting mutations. Cells with an extra copy of a chromosome — known as trisomic cells — grew slower in lab dishes and formed smaller tumors in mice than cells with cancer mutations but no extra chromosomes. Even when trisomic cells carry cancer-associated genes on the extra chromosome, the cells make less than usual of the cancer-driving proteins produced from those genes, Sheltzer reported December 5 at the annual meeting of the American Society for Cell Biology.
Extra chromosomes aren’t entirely off the hook for promoting cancer, though. After cells carrying extra chromosomes were grown with a low dose of chemotherapy drugs, they grew faster than cells that don’t have extra chromosomes, Sheltzer discovered. That could be because cells remaining after chemotherapy have developed additional abnormalities that might make the cancer more aggressive, he said.
BOSTON — Guidebook claims about the superior acoustics of the ancient Greek amphitheater of Epidaurus are a tad melodramatic. An actor’s voice can be heard in the back row, but whispers and other quiet noises cannot, acoustician Remy Wenmaekers reported June 28 at a meeting of the Acoustical Society of America.
The acoustics of the 14,000-seat theater, which dates to the fourth century B.C., are often touted as carrying faint sounds with extraordinary clarity. Wenmaekers and colleagues at Eindhoven University of Technology in the Netherlands positioned microphones at 264 spots throughout the theater and recorded a slow whooping sound projected from the stage that went from low to high frequency with time like a fire truck siren. The team also recorded sounds made by a voice simulator that mimics the frequency spectrum of a male speaker. These tests provided acoustic parameters such as sound strength and reverberation time for various spots in the audience. Then, in a lab, researchers determined the threshold for hearing noises such as a pin dropping or person whispering against the background noise of the theater.
With no roads of humming traffic nearby, the theater, which is still in use today, is remarkably quiet, especially when there’s no wind, Wenmaekers said. But sounds like tearing a sheet of paper or striking a match would be discernable only for someone sitting near the stage. The sound of a dropped coin would just barely be audible for someone seated in the back, but a dropped pin would be too quiet to hear. It’s still unknown just how far noise made by an audience member unwrapping a piece of candy carries.
Some people might think that online privacy is a, well, private matter. If you don’t want your information getting out online, don’t put it on social media. Simple, right?
But keeping your information private isn’t just about your own choices. It’s about your friends’ choices, too. Results from a study of a now-defunct social media site show that the inhabitants of the digital age may need to stop and think about just how much they control their personal information, and where the boundaries of their privacy are.
When someone joins a social network, the first order of business is, of course, to find friends. To aid the process, many apps offer to import contact lists from someone’s phone or e-mail or Facebook, to find matches with people already in the network.
Sharing those contact lists seems innocuous, notes David Garcia, a computational social scientist at the Complexity Science Hub Vienna in Austria. “People giving contact lists, they’re not doing anything wrong,” he says. “You are their friend. You gave them the e-mail address and phone number.” Most of the time, you probably want to stay in touch with the person, possibly even via the social media site.
But the social network then has that information — whether or not the owner of it wanted it shared.
Social platforms’ ability to collect and curate this extra information into what are called shadow profiles first came to light with a Facebook bug in 2013. The bug inadvertently shared the e-mail addresses and phone numbers of some 6 million users with all of their friends, even when the information wasn’t public.
Facebook immediately addressed the bug. But afterward, some users noticed that the phone numbers on their Facebook profiles had still been filled in — even though they had not given Facebook their digits. Instead, Facebook had collected the numbers from the contact lists innocently provided by their friends, and filled in the missing information for them. A shadow profile had become reality. It’s no surprise that a social platform could take names, e-mail addresses and phone numbers and match them up with other people on the same platform. But Garcia wondered if these shadow profiles could be extended to people not on the social platform at all.
He turned to a now-defunct social network called Friendster. A precursor to sites like MySpace and Facebook, Friendster launched in 2002. In 2008, the social site boasted more than 115 million users. But by 2009 people began to jump ship for other sites, and in 2015 Friendster closed for good. Millions of abandoned public profiles vanished into the ether.
Or did they? The Internet Archive — a nonprofit library — has an archive of more than 200 billion web pages, including Friendster. Garcia was able to use that repository to get data on 100 million public accounts from the social media site. Garcia dug through the records in a process he calls Internet Archaeology, after a satirical video from The Onion in which an internet archaeologist announces that he has, ironically, discovered Friendster. “The time scale of online media is very fast, but it’s still studying things in society that don’t exist anymore,” he explains.
Garcia hunted for patterns in the data. Most people don’t have a random assortment of friends. Married people tend to be friends with other married people, for example. But people also have connections that complicate the ability to predict who’s connected to who. People who identified as gay men were more likely to be friends with other gay men, but also likely to be friends with women. Straight women were more likely to be friends with men.
Using this information, Garcia was able to show that he could predict characteristics such as the marital status and sexual orientation of users’ friends who were not on the social media network. And the more people in the social network who shared their own personal information, the more information the network received about their contacts, and the better the prediction about people not on the network got.
“You are not in full control of your privacy,” he concludes. If your friend is on a social platform, so are you. And you don’t have a choice in the matter. Garcia published his findings August 4 in Science Advances.
This does not mean that social platforms are creating shadow profiles of your social media–averse friends, Garcia notes. But with the information people give to social networks and with the platforms’ computing abilities, they certainly could. To prevent the data being used this way, Garcia only used the most basic, public information. He didn’t predict anything about specific people. He only checked to see if it was possible. Garcia also kept the power of his predictions low and very general. And he was careful to not construct an algorithm that could actually build a shadow profile, to make sure that others cannot misuse the findings.
But the results do show that information from your friends on a social network could accurately predict your marital status, location, sexual orientation or political affiliation — information that you may not want anyone to know, let alone in a social network you’re not even on.
“It’s a good illustration of an issue we have in society, which is that we no longer have control over what people can infer about us,” says Elena Zheleva, a computer scientist at the University of Illinois in Chicago. “If I decide not to participate in a certain social network, that doesn’t mean that people won’t be able to find things about me on that network.”
This means we might need to think differently about what privacy means. “We’re used to thinking of having a private space,” Garcia says. “We think we’ve got a room with keys and we let some people in.” But a better image, he argues, might be to imagine ourselves covered in the wet paint of our personal information. If we touch someone else, we leave a handprint. “The more you touch other people, the more you leave on them,” he explains. Touch enough people, and anyone who looks at those people and their paint-covered sleeves will be able to pick out your personal shade of teal.
And because we are no longer in full control of our privacy, Garcia notes, it also means that protecting privacy isn’t something any one person can do. “In some sense it resembles climate change,” he says. “It’s not something you can solve on your own. It’s everyone’s problem or it’s no one’s problem.”
While volunteering at the University of New Mexico’s Children’s Hospital in Albuquerque, Quinton Smith quickly realized that he could never be a physician.
Then an undergrad at the university, Smith was too sad seeing sick kids all the time. But, he thought, “maybe I can help them with science.”
Smith had picked his major, chemical engineering, because he saw it as “a cooler way to go premed.” Though he ultimately landed in the lab instead of at the bedside, he has remained passionate about finding ways to cure what ails people.
Today, his lab at the University of California, Irvine uses tools often employed in fabricating tiny electronics to craft miniature, lab-grown organs that mimic their real-life counterparts. “Most of the time, when we study cells, we study them in a petri dish,” Smith says. “But that’s not their native form.” Prodding cells to assemble into these 3-D structures, called organoids, can give researchers a new way to study diseases and test potential treatments.
By combining Silicon Valley tech and stem cell biology, scientists are now “making tissues that look and react and function like human tissues,” Smith says. “And that hasn’t been done before.”
The power of stem cells Smith’s work began in two dimensions. During his undergraduate studies, he spent two summers in the lab of biomedical engineer Sharon Gerecht, then at Johns Hopkins University. His project aimed to develop a device that could control oxygen and fluid flow inside minuscule chambers on silicon wafers, with the goal of mimicking the environment in which a blood vessel forms. It was there that Smith came to respect human induced pluripotent stem cells.
These stem cells are formed from body cells that are reprogrammed to an early, embryonic stage that can give rise to any cell type. “It just blew my mind that you can take these cells and turn them into anything,” Smith says.
Smith ultimately returned to Gerecht’s lab for his Ph.D., exploring how physical and chemical cues can push these stem cells toward becoming blood vessels. Using a technique called micropatterning — where researchers stamp proteins on glass slides to help cells attach — he spurred cells to organize into the beginnings of artificial blood vessels. Depending on the pattern, the cells formed 2-D stars, circles or triangles, showing how cells come together to form such tubular structures. While a postdoc at MIT, he transitioned to 3-D, with a focus on liver organoids.
Like branching blood vessels, a network of bile ducts carry bile acid throughout the liver. This fluid helps the body digest and absorb fat. But artificial liver tissue doesn’t always re-create ducts that branch the way they do in the body. Cells growing in the lab “need a little bit of help,” Smith says. To get around the problems, Smith and his team pour a stiff gel around minuscule acupuncture needles to create channels. After the gel solidifies, the researchers seed stem cells inside and douse the cells in chemical cues to coax them to form ducts. “We can create on-demand bile ducts using an engineering approach,” he says.
This approach to making liver organoids is possible because Smith speaks the language of biology and the language of engineering, says biomedical engineer Sangeeta Bhatia, a Howard Hughes Medical Institute investigator at MIT and Smith’s postdoc mentor. He can call on his cell biology knowledge and leverage engineering techniques to study how specific cell types are organized to work together in the body.
For example, Smith’s lab now uses 3-D printing to ensure liver tissues grown in the lab, including blood vessels and bile ducts, organize in the right way. Such engineering techniques could help researchers study and pinpoint the root causes behind some liver diseases, such as fatty liver disease, Smith says. Comparing organoids grown from cells from healthy people with those grown from cells from patients with liver disease — including Hispanic people, who are disproportionately affected — may point to a mechanism.
Looking beyond the liver But Smith isn’t restricting himself to the liver. He and his trainees are branching out to explore other tissues and diseases as well.
One of those pursuits is preeclampsia, a disease that affects pregnant women, and disproportionately African American women. Women with preeclampsia develop dangerously high blood pressure because the placenta is inflamed and constricting the mother’s blood vessels. Smith plans to examine lab-grown placentas to determine how environmental factors such as physical forces and chemical cues from the organ impact attached maternal blood vessels.
“We’re really excited about this work,” Smith says. It’s only recently that scientists have tricked stem cells to enter an earlier stage of development that can form placentas. These lab-grown placentas even produce human chorionic gonadotropin, the hormone responsible for positive pregnancy tests.
