Cell (biology)

Concerns explode over new health risks of vaping

exploding atomizer
exploding atomizer

Vaping is not risk-free, especially for kids and teens. A host of new studies have now uncovered worrisome health concerns. For instance, the atomizer shown here can make vapors hotter and riskier to health.

When Irfan Rahman talked to young vapers, some complained of bleeding mouths and throats. And these bloody sores seemed slow to heal. Such reports concerned this toxicologist at the University of Rochester in New York. So he decided to investigate what the vapors inhaled from electronic cigarettes might be doing to mouth cells.

Last October, his team showed those vapors inflame mouth cells in ways that could potentially promote gum disease. That gum damage can destroy the tissues that hold teeth in place. So severe gum disease could lead to tooth loss.

But that’s hardly the end of it.

Vapers inhale those same gases and particles into their lungs. Rahman wondered what effects those vapors might have on cells there. One gauge would be to test how long any lung-cell damage took to heal. And his latest data confirm that e-cigarette vapors also make it hard for lung cells to repair damage.

Students as young as 12 or 13 are now more likely to vape than to smoke. Many are under the impression that because e-cigs don’t contain tobacco, they pose little risk to health. Wrong.

Over the past few months, research has turned up evidence that vaping can pose many brand new risks. The vapors mess with immunity, some studies show. “Smoker’s cough” and bloody sores have begun showing up in teen vapers. The hotter a vaped liquid gets, the harsher its effects on human cells. And a relatively new vaping behavior called “dripping” ups the heat. This threatens to intensify a teen’s risks from those vapors.

Some new data even suggest that e-cig vapors may contain cancer-causing chemicals.

“There are a lot of potentially harmful substances in e-cigarettes. If you’re a teen with your whole life in front of you, why take that risk?” asks Rob McConnell. He’s an internal medicine specialist at the University of Southern California (USC) in Los Angeles.

The newly emerging data suggest that adolescents ignore these risks at their peril.

Cells in the body face constant damage from foreign substances, infections and injury. Most times, nothing bad happens to their host. That’s because the body has a system in place to heal itself. Most major organs have special cells — fibroblasts (FY-broh-blasts) — that repair damaged or injured tissue.

Fibroblasts make up the connective tissues that keep organs in place. But when injured, these cells morph into wound-healers. “If you cut your hand, fibroblasts are the guys that are going to come in and help heal it,” explains Rahman.

In their wound-healing form, fibroblasts at the edges of a cut will shrink. This causes the wound to close up. This squeezing or contraction of the skin takes a lot of energy. Fortunately, fibroblasts are powered by cellular engines. Called mitochondria (My-toh-KON-dree-uh), these tiny powerhouses turn food (sugar) into fuel.

fibroblast cells
Fibroblast cells (such as those seen here) repair damaged or injured tissues. The cells’ nuclei are colored blue. Their mitochondria are red. Filaments (green) help the fibroblast contract.

In the lab, Rahman and his colleagues grew lung fibroblasts in Petri dishes. Then they cut into the community of growing cells to mimic a wound. Afterward, they exposed the growing cells to e-cigarette vapors.

As expected, the fibroblasts morphed into wound-healing cells. But unexpectedly, they didn’t close up the cut. Curious, Rahman looked more closely at the cellular machinery. Some mitochondria had been destroyed. The fibroblasts simply had run out of the energy they needed before they could successfully squeeze the wound closed.

Rahman’s team described its findings March 3 in Scientific Reports.

It’s not clear yet if the fibroblast damage that Rahman showed in the lab signals that wounds will heal more slowly in people who vape. After all, in the lab, scientists can manipulate one variable at a time while holding other factors constant. But in the body, many processes will be at work all at once. This can make it harder to tease out whether such lab tests mimic well what would happen to an otherwise healthy person.

And that’s why Rahman now hopes to compare rates of wound healing in people who vape to rates in those who don’t. For now, however, he’s worried that what he saw in the lab may indeed mimic risks to people.

Smoker’s cough becomes vaper’s cough?

Inhaling pollution can irritate the lungs. And when the assaulting particles are breathed in regularly, the lungs tend to respond by triggering a cough that won’t go away, explains McConnell at USC. He has been studying the effects of air pollution in kids. Inhaling irritating particles or gases may lead to bronchitis (Bron-KY-tis). That’s when the airways that channel oxygen to the lungs become irritated and inflamed.

bronchitis girl
Researchers have found evidence that vaping can irritate the lungs and lead to chronic wheezing and coughs, a condition known as bronchitis.

Bronchitis may cause wheezing, too, and coughs that bring up thick mucus known as phlegm (FLEM). The germs that cause colds, flu and bacterial infections can sometimes trigger bronchitis. So can breathing in heavily polluted air, tobacco smoke or certain chemical fumes.

When these symptoms don’t go away, the bronchitis is called chronic (KRON-ik). And cigarette smoking is its most common cause. That’s why chronic bronchitis is typically referred to as “smoker’s cough.”

McConnell’s team decided to look for signs of bronchitis in vaping teens. After all, he explains, “There are a lot of these irritants in e-cigarette vapor.”

The researchers asked 2,000 students in the Los Angeles, Calif., area about their vaping habits. All were in their last two years of high school. The researchers also asked the teens about any respiratory symptoms. These could include coughs or phlegm.

Anyone who reported a daily cough for at least three straight months was judged to have chronic bronchitis. A student with persistent phlegm or congestion for three months or more…

New stem cell method produces millions of human brain and muscle cells in days

Scientists at the University of Cambridge and the Wellcome Trust Sanger Institute have created a new technique that simplifies the production of human brain and muscle cells – allowing millions of functional cells to be generated in just a few days.

Human pluripotent stem cells are ‘master cells’ that have the ability to develop into almost any type of tissue, including brain cells. They hold huge potential for studying human development and the impact of diseases, including cancer, Alzheimer’s, multiple sclerosis, and heart disease.

In a human, it takes nine to twelve months for a single brain cell to develop fully. It can take between three and 20 weeks using current methods to create human brain cells, including grey matter (neurons) and white matter (oligodendrocytes) from an induced pluripotent stem cell – that is, a stem cell generated by reprogramming a skin cell to its ‘master’ stage. However, these methods are complex and time-consuming, often producing a mixed population of cells.

Opti-OX

The new platform technology, OPTi-OX, optimises the way of switching on genes in human stem cells. Scientists applied OPTi-OX to the production of millions of nearly identical cells in a matter of days. In addition to the neurons, oligodendrocytes, and muscle cells the scientists created in the study, OPTi-OX holds the possibility of generating any cell type at unprecedented purities, in this short timeframe.

Producing neurons, oligodendrocytes and muscle cells

To produce the neurons, oligodendrocytes, and muscle cells, the team altered the DNA in…

Immune cells play surprising role in steady heartbeat

macrophages and heart cells
IT’S ELECTRIFYING Macrophages (green) “plug in” to heart cells (light purple and pink), providing an electrical boost that helps the heart cells contract and pump blood, a study in mice finds.

Immune system cells may help your heart keep the beat. These cells, called macrophages, usually protect the body from invading pathogens. But a new study published April 20 in Cell shows that in mice, the immune cells help electricity flow between muscle cells to keep the organ pumping.

Macrophages squeeze in between heart muscle cells, called cardiomyocytes. These muscle cells rhythmically contract in response to electrical signals, pumping blood through the heart. By “plugging in” to the cardiomyocytes, macrophages help the heart cells receive the signals and stay on beat.

Researchers have known for a couple of years that macrophages live in healthy heart tissue. But their specific functions “were still very much a mystery,” says Edward Thorp, an immunologist at Northwestern University’s Feinberg School of Medicine in Chicago. He calls the study’s conclusion that macrophages electrically couple with cardiomyocytes “paradigm shifting.” It highlights “the functional diversity and physiologic importance of macrophages, beyond their role in host defense,” Thorp says.

Matthias Nahrendorf, a cell biologist at Harvard Medical School, stumbled onto this electrifying find by accident.

Curious about how macrophages impact the heart, he tried to perform a cardiac MRI on a mouse genetically engineered to not have the immune cells. But the rodent’s heartbeat was too slow and irregular to…

Cells’ stunning complexity on display in a new online portal

3-D images of cells
VARIATIONS ON A CELL Although these stem cells are all genetically identical, they can adopt a variety of shapes. Here, the cells’ membranes are cyan, and DNA is colored magenta.

Computers don’t have eyes, but they could revolutionize the way scientists visualize cells.

Researchers at the Allen Institute for Cell Science in Seattle have devised 3-D representations of cells, compiled by computers learning where thousands of real cells tuck their component parts.

Most drawings of cells in textbooks come from human interpretations gleaned by looking at just a few dead cells at a time. The new Allen Cell Explorer, which premiered online April 5, presents 3-D images of genetically identical stem cells grown in lab dishes (composite, above), revealing a huge variety of structural differences.

Each cell comes from a skin cell that was reprogrammed into a stem cell. Important proteins were tagged with fluorescent molecules so researchers could keep tabs on the cell membrane, DNA-containing nucleus, energy-generating mitochondria, microtubules and other cell parts. Using the 3-D images, computer programs learned where the cellular parts are in relation to each other. From those rules, the programs can generate predictive transparent models of a cell’s structure (below). The new views, which can capture cells at different time points, may offer clues into their inner workings.

3-D view of a cell
Machine-learning programs…

New Therapy Shrinks Five Types of Pediatric Cancers in Mice

Cancerous pediatric brain tumors are some of the most aggressive cancers to affect children, and are frequently fatal. They’re difficult to treat due to their proximity to sensitive brain tissue in tiny brains, and children’s bodies can rarely tolerate the side effects of the levels of chemotherapy and radiation necessary to shrink tumors.

But recently, researchers at Stanford Medicine, the Lucile Packard Children’s Hospital, and several other institutions successfully tested a promising immunotherapy treatment that shrank multiple tumor types in mouse models. Immunotherapy treatments harness the body’s own immune system to fight the cancer, and usually come with few to no side effects compared to chemotherapy drugs and radiation.

The collaborative study, published in Science Translational Medicine, showed results on the five most common types of pediatric tumors: Group 3 medulloblastomas (MB), atypical teratoid rhabdoid tumors (ATRT), primitive neuroectodermal tumors (PNET), pediatric glioblastoma (PG), and diffuse intrinsic pontine glioma (DIPG).

The Stanford researchers designed their study after the recent discovery of a molecule known as CD47, a protein expressed on the surface of all cells. CD47 sends a “don’t eat me” signal to the immune system’s macrophages—white blood cells whose job it is to destroy abnormal cells. “Think of the macrophages as the Pac-Man of the immune system,” Samuel Cheshier, lead study author and assistant professor of neurosurgery at Stanford Medicine, tells mental_floss.

Cancer cells have adapted to express high amounts of CD47, essentially fooling the immune system into not destroying their cells, which allows tumors to flourish. Cheshier and his team theorized that if they could block the CD47 signals on cancer cells, the macrophages would identify the cells on the cancerous tumors and eat them—without any toxicity to healthy cells. To do so, they used an antibody known as anti-CD47, which, as its name implies, blocks CD47 on the cancer from binding to a receptor on the macrophage called SIRP-alpha.

“It is this binding that tells the macrophage, ‘Don’t eat the tumor,’” he says. The anti-CD47 fits perfectly into the binding pocket where CD47 and SIRP-alpha interact, “like a jigsaw puzzle,” helping the macrophage correctly identify the tumor as something to be removed. “Anti-CD47 is the big power pill in Pac-Man that makes him able to eat the ghosts,” says Cheshier.

Even better, not only does…

CRISPR had a life before it became a gene-editing tool

phages
Bacteria and archaea armed with CRISPR systems have been at war with viruses for eons. Here, hordes of viruses known as phages assault a bacterium to turn it into a virus-making factory.

WEAPONS OF MASS EVOLUTION

It is the dazzling star of the biotech world: a powerful new tool that can deftly and precisely alter the structure of DNA. It promises cures for diseases, sturdier crops, malaria-resistant mosquitoes and more. Frenzy over the technique — known as CRISPR/Cas9 — is in full swing. Every week, new CRISPR findings are unfurled in scientific journals. In the courts, universities fight over patents. The media report on the breakthroughs as well as the ethics of this game changer almost daily.

But there is a less sequins-and-glitter side to CRISPR that’s just as alluring to anyone thirsty to understand the natural world. The biology behind CRISPR technology comes from a battle that has been raging for eons, out of sight and yet all around us (and on us, and in us).

The CRISPR editing tool has its origins in microbes — bacteria and archaea that live in obscene numbers everywhere from undersea vents to the snot in the human nose. For billions of years, these single-celled organisms have been at odds with the viruses — known as phages — that attack them, invaders so plentiful that a single drop of seawater can hold 10 million. And natural CRISPR systems (there are many) play a big part in this tussle. They act as gatekeepers, essentially cataloging viruses that get into cells. If a virus shows up again, the cell — and its offspring — can recognize and destroy it. Studying this system will teach biologists much about ecology, disease and the overall workings of life on Earth.

But moving from the simple, textbook story into real life is messy. In the few years since the defensive function of CRISPR systems was first appreciated, microbiologists have busied themselves collecting samples, conducting experiments and crunching reams of DNA data to try to understand what the systems do. From that has come much elegant physiology, a mass of complexity, surprises aplenty — and more than a little mystery.

Spoiled yogurt

The biology is complicated, and its basic nuts and bolts took some figuring out. There are two parts to CRISPR/Cas systems: the CRISPR bit and the Cas bit. The CRISPR bit — or “clustered regularly interspaced short palindromic repeats” — was stumbled on in the late 1980s and 1990s. Scientists then slowly pieced the story together by studying microbes that thrive in animals’ guts and in salt marshes, that cause the plague and that are used to make delicious yogurt and cheese.

None of the scientists knew what they were dealing with at first. They saw stretches of DNA with a characteristic pattern: short lengths of repeated sequence separated by other DNA sequences now known as spacers. Each spacer was unique. Because the roster of spacers could differ from one cell to the next in a given microbe species, an early realization was that these differences could be useful for forensic “typing” — investigators could tell whether food poisoning cases were linked, or if someone had stolen a company’s yogurt starter culture.

Bacteria use CRISPR/Cas as a form of immunity or self-defense against invaders. A bacterium builds a library of genetic material from past invaders so that, if the same invader attacks again, the bacterium and its offspring can disable it.

L. Marraffini/Nature 2015, Adapted by J. Hirshfeld

But curious findings piled up. Some of those spacers, it turned out, matched the DNA of phages. In a flurry of reports in 2005, scientists showed, to name one example, that strains of the lactic acid bacterium Streptococcus thermophilus contained spacers that matched genetic material of phages known to infect Streptococcus. And the more spacers a strain had, the more resistant it was to attack by phages.

This began to look a lot like learned or adaptive immunity, akin to our own antibody system: After exposure to a specific threat, your immune system remembers and you are thereafter resistant to that threat. In a classic experiment published in Science in 2007, researchers at the food company Danisco showed it was so. They could see new spacers added when a phage infected a culture of S. thermophilus. Afterward, the bacterium was immune to the phage. They could artificially engineer a phage spacer into the CRISPR DNA and see resistance emerge; when they took the spacer away, immunity was lost.

This was handy intel for an industry that could find whole vats of yogurt-making bacteria wiped out by phage infestations. It was an exciting time scientifically and commercially, says Rodolphe Barrangou of North Carolina State University in Raleigh, who did a lot of the Danisco work. “It was not just discovering a cool system, but also uncovering a powerful phage-resistance technology for the dairy industry,” he says.

The second part of the CRISPR/Cas system is the Cas bit: a set of genes located near the cluster of CRISPR spacers. The DNA sequences of these genes strongly suggested that they carried instructions for proteins that interact with DNA or RNA in some fashion — sticking to it, cutting it, copying it, unraveling it. When researchers inactivated one Cas gene or another, they saw immunity falter. Clearly, the two bits of the system — CRISPR and Cas — were a team.

It took many more experiments to get to today’s basic model of how CRISPR/Cas systems fight phages — and not just phages. Other types of foreign DNA can get into microbes, including circular rings called plasmids that shuttle from cell to cell and DNA pieces called transposable elements, which jump around within genomes. CRISPRs can fend off these intruders, as well as keep a microbe’s genome in tidy order.

The process works like this: A virus injects its genetic material into the cell. Sensing this danger, the cell selects a little strip of that genetic material and adds it to the spacers in the CRISPR cluster. This step, known as immunization or adaptation, creates a list of encounters a cell has had with viruses, plasmids or other foreign bits of DNA over time — neatly lined up in reverse chronological order, newest to oldest.

Older spacers eventually get shed, but a CRISPR cluster can grow to be long — the record holder to date is 587 spacers in Haliangium ochraceum, a salt-loving microbe isolated from a piece of seaweed. “It’s like looking at the last 600 shots you had in your arm,” says Barrangou. “Think about that.”

New spacer in place, the microbe is now immunized. Later comes targeting. If that same phage enters the cell again, it’s recognized. The cell has made RNA copies of the relevant spacer, which bind to the matching spot on the genome of the invading phage. That “guide RNA” leads Cas proteins to target and snip the phage DNA, defanging the intruder.

Scientists have divided the array of known CRISPR systems into five types and 16 subtypes based on DNA sequence data. The distribution of types differs in archaea and bacteria.

K.S. Makarova et al/Nat. Rev. Microbio. 2015, Adapted by J. Hirshfeld

Researchers now know there are a confetti-storm of different CRISPR systems, and the list continues to grow. Some are simple — such as the CRISPR/Cas9 system that’s been adapted for gene editing in more complex creatures (SN: 4/15/17, p. 16) — and some are elaborate, with many protein workhorses deployed to get the job done.

Those who are sleuthing the evolution of CRISPR systems are deciphering a complex story. The part of the CRISPR toolbox involved in immunity (adding spacers after phages inject their genetic material) seems to have originated from a specific type of transposable element called a casposon. But the part responsible for targeting has multiple origins — in some cases, it’s another type of transposable element. In others, it’s a mystery.

Given the power of CRISPR systems to ward off foes, one might think every respectable microbe out there in the soils, vents, lakes, guts and nostrils of this planet would have one. Not so.

Numbers are far from certain, partly because science hasn’t come close to identifying all the world’s microbes, let alone probe them all for CRISPRs. But the scads of microbial genetic data accrued so far throw up interesting trends.

Tallies suggest that CRISPR systems are far more prevalent in known archaea than in known bacteria — such systems exist in roughly 90 percent of archaea and about…

Engineered immune cells boost leukemia survival for some

CAR-T cell attacking a leukemia cell
IMMUNE ATTACK Doctors can engineer a patient’s own immune cells to kill cancer cells. These engineered cells, called CAR-T cells, were effective for some people against relapses of leukemia over the long term. Here, a CAR-T cell (red) attacks a leukemia cell (yellow).

WASHINGTON — Immune cells engineered to hunt and destroy cancer cells may help some people with acute lymphoblastic leukemia (ALL) live much longer.

Outcomes depended upon disease severity before treatment, oncologist Jae Park reported April 3 at the American Association for Cancer Research annual meeting.

In ALL — expected to strike 5,970 people and kill 1,440 in the United States in 2017 — immune cells called B cells grow out of control in bone marrow and can spread to other tissues. Overall, five-year survival rates are 71 percent. But fewer than 10…

5 Labs That Use 3D Printing for Biohacking Projects

The greatest bridge between the world of makers and the world of biohackers is probably the mighty 3D printer. The main difference is instead of using plastics, they’re using biomaterials to build three-dimensional structures, and using special bioinks made of living cells to print messages and patterns.

Human cells cultured into a decellularized apple slice (left) and an apple carved into an ear shape (right) from Pelling Labs. Photo by Bonnie Findley

How BioCurious Started Bioprinting

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BioCurious is a mandatory stop among biohacker communities in North America. This pioneering space, located in Sunnyvale, California, hosts a number of great people collaborating on the DIY BioPrinter project. Their bioprinting adventure started in 2012, when they had their first meetups. According to Patrik D’haeseleer, who is leading the project with Maria Chavez, they were looking for community projects that could bring new people into the space and let them quickly collaborate. None of the project leaders had a specific bioprinting application in mind, nor did they have previous knowledge on how to build this kind of printer. Still, it appeared to be a fairly approachable technology that people could play with.

“You can just take a commercial inkjet printer. Take the inkjet cartridges and cut off the top essentially. Empty out the ink and put something else in there. Now you can start printing with that,” D’haeseleer explains.

The BioCurious group started by printing on big coffee filters, substituting ink with arabinose, which is a natural plant sugar. Then they put the filter paper on top of a culture of E. coli bacteria genetically modified to produce a green fluorescent protein in the presence of arabinose. The cells started to glow exactly where arabinose was printed.

Modifying commercial printers for this, as they were doing, presented challenges. “You may need to reverse engineer the printer driver or disassemble the paper handling machinery in order to be able to do what you want,” says D’haeseleer.

First major success with BioCurious’ $150 DIY BioPrinter: fluorescent E. coli printed on agar with an inkjet printhead. Photo by Patrik Dʼhaeseleer

So the group decided to build their own bioprinter from scratch. Their second version uses stepper motors from CD drives, an inkjet cartridge as a print head, and an open source Arduino shield to drive it — a DIY bioprinter for just $150 that you can find on Instructables.

The next and still current challenge deals with the consistency of the ink. Commercial cartridges work with ink that is pretty watery. But bioink requires a more gel-like material with high viscosity. The DIY BioPrinter group has been experimenting with different syringe pump designs that could allow them to inject small amounts of viscous liquid through the “bio print head.”

BioCurious’ early printer: $11 syringe pumps mounted on a platform made from DVD drives. Photo by Patrik Dʼhaeseleer

Moving to 3D

Starting with an already existing 3D platform seemed like the best way to go beyond 2D patterns. The group first tried to modify their existing 3D printer by adding a bio print head directly on it. However, their commercial machine required some difficult reverse engineering and software modification to perfect the process. After a couple of months, this led to a dead end.

The RepRap family of 3D printers influenced the next step. After buying an affordable open source printer kit, the bioprinting team was able to switch out the plastic extruding print head for a print head with flexible tubes that connected to a set of stationary syringe pumps. It worked.

Converting a RepRap into BioCurious’ latest 3D BioPrinter platform, with an Open…

Scientists move closer to building synthetic yeast from scratch

Saccharomyces cerevisiae yeast
BUDDING STAR With five more synthetic chromosomes built, scientists are closer to creating a synthetic genome for Saccharomyces cerevisiae yeast (shown).

Synthetic yeast is on the rise.

Scientists have constructed five more yeast chromosomes from scratch. The new work, reported online March 9 in Science, brings researchers closer to completely lab-built yeast.

“We’re doing it primarily to learn a little more about how cells are wired,” says geneticist Jef Boeke of the New York University Langone Medical Center. But scientists might also be able to tinker with a synthetic yeast cell more efficiently than a natural one, allowing more precise engineering of everything from antiviral drugs to biofuels.

Boeke was…