Device Tracks Blood Flow in the Brain

Biomedicine

A headset ultrasound monitor could make it easier to detect the dangerous aftereffects of brain injuries.

• By Courtney Humphries

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A new ultrasound device could make it easier to detect a potentially life-threatening condition that is common in soldiers with blast-related brain injuries and patients who survive aneurysms.
The condition, called cerebral vasospasm, occurs when blood vessels suddenly constrict. The effect is like squeezing a garden hose: the velocity inside the artery builds as pressure grows, and less blood flows to the brain. The condition can develop several days after an initial injury, and is currently detected using ultrasound, which requires a trained technician to find the relevant blood vessels and hold the ultrasound beam in place.
PhysioSonics, based in Bellevue, Washington, has developed a monitor that makes this process automatic, eliminating the need for a technician. The company is adapting the product for military use, and hopes to expand it to also detect a potentially dangerous buildup of pressure inside the head.
The company's monitor consists of a headset that directs an array of ultrasound beams through the head and uses a proprietary algorithm to automatically detect the mid-cerebral artery, one of the major arteries supplying blood to the brain. The device then locks the relevant beam onto the artery and measures its blood flow. A machine attached to the headset gives an index of flow and peak velocity.

"The point is to give you a variable" that could be read similarly to a heart-rate monitor, says Michel Kliot, company cofounder and a neurosurgeon at University of Washington, where the technology was initially developed.
In November, the company received a military grant of $2.5 million to adapt the device for monitoring vasospasm in soldiers. Nearly half the soldiers who sustain blast injuries develop vasospasm, and the company plans to make a more rugged version of its commercial device for the battlefield.
The device could also be used to monitor patients who survive aneurysm ruptures, a high proportion of whom develop vasospasm. For such patients, a technician would typically measure blood flow with an ultrasound once or twice a day during a hospital stay of several days. Kliot says the new device makes it possible to continuously monitor patients at high risk, and for longer periods of time. "We see putting it on the head and measuring constantly or frequently over two weeks," says Kliot.
Nerissa Ko, a neurologist in the intensive care unit at University of California San Francisco Medical Center, says the device is building on a well-accepted diagnostic technology, with the added innovation of automation. If it proves effective, she says, the device could make it easier to track blood flow over time, which she says is the best way to detect vasospasm.
Brad Harlow, president and CEO of PhysioSonics, says the company has conducted a study comparing the algorithm's accuracy to a technician's and is filing for approval from the U.S. Food and Drug Administration within the month.
The company has also been developing an algorithm that would use the same technology to monitor pressure inside the head. Such monitoring currently requires doctors to drill a hole in the skull. Ko cautions, however, that while the blood-flow changes detected by ultrasound could serve as a surrogate for direct pressure measurements, it's still not clear if the device is sensitive enough to monitor the subtle changes that can signal danger.

Fluorescent Protein Lights Up the Inner Workings of the Brain

Light up: Applying voltage to the neurons shown here caused an increase in fluorescence.
Adam Cohen, Harvard University

BIOMEDICINE

Fluorescent Protein Lights Up the Inner Workings of the Brain

The advance offers a nontoxic way to study how the organ works, and how disease impairs it.

• BY ERICA WESTLY

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Interactions between neurons involve both chemical and electrical signaling. For decades, neuroscientists have searched for a noninvasive way to measure the electrical component. Achieving this could make it easier to study how the brain works, and how neurological disease impairs its functioning.

One promising approach is tracking neuronal electrical activity with fluorescence, which can be integrated into cells fairly easily through genetics or by being attached to antibodies, but which can be toxic and slow to work. Last week, researchers introduced a new candidate—a fluorescent protein from a Dead Sea microbe—that appears to be better equipped for the challenge.

The protein, called archaerhodopsin-3, or Arch, was discovered more than 10 years ago, but scientists are just now starting to realize its potential as a research tool. In a study published last year, researchers used light to trigger an electrical response from Arch that silenced overactive neurons—an approach that could lead to new therapeutics for epilepsy and other seizure disorders.

In this study, the researchers took the opposite tack and used electricity to elicit changes in Arch's fluorescence. The approach could lead to more accurate methods for recording electrical signals from the brain.

The results, published in Nature Methods, indicate that Arch could be the noninvasive voltage sensor neuroscientists have been looking for: It's not toxic to cells, and it's sensitive and fast enough to pick up the rapid electrical changes that accompany neuronal activity.

"It looks order of magnitudes better than any of the other optical imaging methods I've seen before," says Darcy Peterka, a neuroscientist at Columbia University who was not involved with the study.

The standard method for recording electrical activity in neurons in cell culture—which involves sticking an electrode into the cell—remains the most accurate for measuring voltage at a single point in the cell. But puncturing a neuron with an electrode eventually kills it, whereas Arch would let researchers follow the electrical signal as it propagates throughout the cell. It would also allow researchers to record from the same cell again and again, allowing for long-term experiments that would not be possible with the standard method.

"It really depends on what scientific questions you're trying to answer," says Adam Cohen, a biophysics researcher at Harvard University and the lead author of the new study.

The study was conducted in cultured mouse neurons, but Cohen and his colleagues plan to use Arch to measure neuronal activity in live animals, starting with simple organisms, such as the zebrafish and the worm C. elegans. One advantage of these animals is that they're transparent, making it easy to see the fluorescent signal through a microscope.

Arch could also prove useful for imaging electrical signals in the mammalian brain, especially for experiments in mice, which could be genetically engineered to express the protein in specific neurons or at specific times in development, for example.

The challenge of transferring the approach to animals is making sure the fluorescent signal stays strong and consistent. "In the living brain, light gets absorbed—for example, by blood—so you lose light," says Ed Boyden, the researcher at MIT who led the study that used Arch to silence neurons.

The fluorescence given off by Arch also isn't as bright as some of the other available dyes, but its low toxicity makes this less of a concern, because researchers could compensate by using higher concentrations. "The fact that they got it to work well in mouse neurons bodes well," says Peterka.

Researchers Turn Cloned Human Embryo into Working Stem Cell Line

But wait, there's a catch

By Clay Dillow

Human Embryonic Stem Cells Vojtech.dostal via Wikimedia

Potentially big stem cell news out of the New York Stem Cell Foundation Laboratory today in Nature, though in our experience it’s always good to temper one’s expectations when it comes to these sorts of things. After all, we’ve thought we cracked the code on embryonic stem cell cloning technology more than once, only to find this kind of biology is much more difficult and complex than originally thought. Nonetheless, researchers have reprogrammed an adult human egg to an embryonic state and used it to create a self-reproducing embryonic stem cell line. And that’s a big deal.

But it’s not the holy grail of stem cell research. The cell line they created doesn’t produce true clones containing perfect copies of the donor’s DNA, and therefore are more or less clinically ineffective. But the development does represent a step forward for the field, and answers some important questions plaguing stem cell science.

So here’s where we’re at: Scientists are trying to take an unfertilized egg, swap out the single set of chromosomes in the egg for the two sets of chromosomes in a patient’s adult cells, and initiate a process wherein the egg develops per the instructions of the new DNA.

Usually, this process fails. Cultures stop developing after a division or two. So the NY Stem Cell team went looking for the root cause of failure. Through a series of experiments they found that whatever the problem is, it’s introduced during the removal of the egg’s native single chromosome DNA. So they did what most of us do--they skipped a step.

They just left the native DNA in there and inserted the donor DNA alongside it. The reprogramming worked, and they produced an embryo that developed up to what’s known as the blastocyst stage, where the culture contains nearly 100 cells. At this point, stem cells can be extracted from the batch.

Of course, there’s still the problem of the extra set of chromosomes rattling around in there. This makes the stem cells incompatible with the DNA donor’s tissue, so from a clinical standpoint they are roughly worthless. But from a research standpoint, a step forward is a step forward. With the problem isolated, they are now looking at new approaches to remove the native DNA from the egg that won’t cause the hiccup that halts cell division. That could take awhile, but at least now we think we’re moving in the right direction.

[Nature]

Correcting Sickle Cell Disease With Stem Cells

This digitally-colorized scanning electron micrograph (SEM) revealed some of the comparative ultrastructural morphology between normal red blood cells (RBCs), and a sickle cell RBC (left). (Credit: CDC / Janice Haney Carr)

Science Daily — Using a patient's own stem cells, researchers at Johns Hopkins have corrected the genetic alteration that causes sickle cell disease (SCD), a painful, disabling inherited blood disorder that affects mostly African-Americans. The corrected stem cells were coaxed into immature red blood cells in a test tube that then turned on a normal version of the gene.

In an article published online August 31 in Blood, the researchers say they are one step closer to developing a feasible cure or long-term treatment option for patients with SCD, which is caused by a single DNA letter change in the gene for adult hemoglobin, the principle protein in red blood cells needed to carry oxygen. People who inherited two copies -- one from each parent -- of the genetic alteration, the red blood cells are sickle-shaped, rather than round. The misshapen red blood cells clog blood vessels, leading to pain, fatigue, infections, organ damage and premature death.

The research team cautions that the work, done only in the laboratory, is years away from clinical use in patients, but should provide tools for developing gene therapies for SCD and a variety of other blood disorders.

Although there are drugs and painkillers that control SCD symptoms, the only known cure -- achieved rarely -- has been bone marrow transplant. But because the vast majority of SCD patients are African-American and few African-Americans have registered in the bone marrow registry, it has been difficult to find compatible donors, says Linzhao Cheng, Ph.D., a professor of medicine and associate director for basic research in the Division of Hematology and also a member of the Johns HopkinsInstitute for Cell Engineering. "We're now one step closer to developing a combination cell and gene therapy method that will allow us to use patients' own cells to treat them."

Using one adult patient at The Johns Hopkins Hospital as their first case, the researchers first isolated the patient's bone marrow cells. After generating induced pluripotent stem (iPS) cells -- adult cells that have been reprogrammed to behave like embryonic stem cells -- from the bone marrow cells, they put one normal copy of the hemoglobin gene in place of the defective one using genetic engineering techniques.

The researchers sequenced the DNA from 300 different samples of iPS cells to identify those that contained correct copies of the hemoglobin gene and found four. Three of these iPS cell lines didn't pass muster in subsequent tests.

"The beauty of iPS cells is that we can grow a lot of them and then coax them into becoming cells of any kind, including red blood cells," Cheng said.

In their process, his team converted the corrected iPS cells into immature red blood cells by giving them growth factors. Further testing showed that the normal hemoglobin gene was turned on properly in these cells, although at less than half of normal levels. "We think these immature red blood cells still behave like embryonic cells and as a result are unable to turn on high enough levels of the adult hemoglobin gene," explains Cheng. "We next have to learn how to properly convert these cells into mature red blood cells."

Only one drug treatment has been approved by the FDA for treatment of SCD, hydroxyurea, whose use was pioneered by George Dover, M.D., the chief of pediatrics at the Johns Hopkins Children's Center. Outside of bone marrow transplants, frequent blood transfusions and narcotics can control acute episodes.

The research was funded by grants from the Maryland Stem Cell Fund and the National Institutes of Health, and a fellowship from the Siebel Foundation.

Gel Lets Doctors Fix Ruptured Blood Vessels without Sutures

Support structure: This latex tube has been treated with heated polaxamer to make it rigid. Doctors could use the gel during surgery to mend vessels with glue rather than sutures.
Credit: Nature

BIOMEDICINE

The new technique could make some delicate surgical procedures quicker and safer.

• BY ALLA KATSNELSON

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A synthetic, temperature-sensitive gel could help surgeons reconnect blood vessels more quickly, safely, and easily. The new gel, successfully tested in rats, could also enable more complex robotic surgery as well as minimally invasive surgery.  

There have been few advances in the art of reconnecting blood vessels since French surgeon Alexis Carrel received the Nobel Prize in 1912 for his method of sewing them together. About a decade ago, surgeon Geoffrey Gurtner found himself longing for a substance that could be poured into the tiny blood vessels he was struggling to reconnect in order to prop them open while he sewed them together. "A lot of surgeries require reconnecting vessels," he says. "For two-thirds of operations, this would be helpful."  

When Gurtner took a post at Stanford University, he partnered with a group of Stanford chemical engineers and biomaterials experts who adapted a substance called Poloxymer 407, which is already approved by the U.S. Food and Drug Administration for internal use, to do the job. 

The trick was to tweak the properties of the substance so that it changes from a liquid to a solid state a few degrees above body temperature. The group used a halogen lamp to heat up the area around a severed blood vessel in rats, added the poloxymer, and then sealed the two ends with surgical glue.

"The liquid turns into a solid, and then instead of a bunch of collapsible floppy pieces of linguini, you have something like pixie sticks," Gurtner says. After connecting them, "you're left with a scarless joint between the two blood vessels."

The group tested the technique in the aorta, as well as tiny, hard-to-reach, and oddly angled blood vessels, of rats. Not only was it five times faster than hand-sewing, the animals also had less scarring and inflammation up to two years later. The technique is described in a study published online in Nature Medicine.

Gurtner isn't the first to attempt such an approach. Roger Khouri, a plastic surgeon and microvascular surgeon based in Miami, patented a similar idea almost 20 years ago.

Khouri used a lipid-based substance that could be cooled to a solid state using cold water, and then dissolved at body temperature. But there were no glues available at the time that could be used in the body, so his team employed surgical staples. "I used the technique on patients, but it never really took off because those staples never held very well," he says.

Gurtner says he hopes to begin testing the technique in patients next year, but would like to improve the glue that his team used. "Having that glue be perfect is really going to make this a no-brainer for doctors," he says.   

But Bruce Klitzman, a biomedical engineer and microvascular physiologist at Duke University, cautions that even if it works as well in humans as the developers hope, it might not be fully embraced by vascular surgeons. "It may save them five or 10 minutes, and if so, they might do it, but then again, you may have flexibility with suture that you may not have with this approach," he says.

Smart Phones Help Manage Chronic Illness

Health tracking: An app developed at the University of Toronto helps people monitor their blood pressure. It interfaces with a wireless blood-pressure monitor and reminds users to take readings.
Credit: University Health Network

BIOMEDICINE

Smart Phones Help Manage Chronic Illness

Apps that connect to medical monitors have been shown to improve the health of people with diabetes and hypertension—and could ease the burden on the health-care system.

• BY EMILY SINGER

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App stores are exploding with programs designed to help people monitor their health using a smart phone. But the majority of these apps merely make it easier for patients to record health measures, such as weight or blood pressure. It's unclear if they actually significantly improve health behavior.

Joseph Cafazzo, a biomedical engineer at the University Health Network, in Toronto, and collaborators have developed apps that do much more. Their apps interface wirelessly with medical devices—including a blood-pressure monitor and a blood-sugar monitor—and offer suggestions based on the readings. They found that people using the programs lowered their blood pressure and were more vigilant about monitoring and testing their blood sugar.

One of the most interesting findings was that doctors seemed to play no role in the change. "It was solely patients becoming responsible for their own care," says Cafazzo, who heads the university's Centre for Global eHealth Innovation.

Cafazzo's efforts were partly a result of the growing use of smart phones as medical tools, as well as an increase in remote and home monitoring devices that are moving medicine outside the doctor's office.

But unlike many existing monitoring systems, Cafazzo sees his work bringing greater responsibility to the patient. "The goal of classic home monitoring is to collect information and deliver it to the doctor, who has to analyze and act on it, then return that information to the patient," he says. "It's not really self-care."

In a yearlong clinical trial of the system involving 110 patients with diabetic hypertension, Cafazzo and colleagues had some people use the app and a home blood-pressure monitor, while others used only a monitor. Those who used the app had a drop in systolic blood pressure of 10 millimeters of mercury, on average, which would reduce the risk of cardiac events by about 25 percent. Those who used just the conventional pressure monitor saw no reduction in blood pressure.

Physicians didn't significantly alter patients' medication or treatment regimens during the course of the study, so researchers say any changes in health must have been solely due to the monitoring app and related changes in patient behavior, such as new eating patterns and better medication compliance. "Just giving the monitor isn't enough," says Cafazzo. "Active telemonitoring keeps patients engaged."Download: he app highlights trends in blood-pressure readings and detects when people forget to take their measurements, reminding them with an automated phone call. Giving patients self-monitoring tools makes them aware of their health stats on a daily basis, rather than just in the week before a doctor's appointment, says Cafazzo. This is especially relevant for hypertension, which doesn't usually have detectable symptoms.

A second project focused on adolescents with diabetes, a challenging population for doctors because teens are transitioning from being cared for by their parents to being responsible for their own care. Researchers worked with Apple to create an app that is compatible with a blood-sugar monitor. The app reminds users to check their blood sugar and rewards users with iTunes certificates for healthy behavior. If it detects a string of low measurements, it will ask users what they think caused the trend. Teens who used the app checked their blood sugar twice as often as those who didn't.

Cafazzo hopes self-monitoring tools like these will be instrumental in changing how chronic conditions, such as diabetes and hypertension, are managed. These conditions represent a huge financial burden on health-care systems. "Primary care isn't the best place for chronic disease management," says Cafazzo. "It should go back to nurses and the patients themselves."

For both apps, researchers won approval from Health Canada (similar to the U.S. Food and Drug Administration) to run the clinical trials. As smart-phone apps become increasingly sophisticated, incorporating external sensors and intelligence to make recommendations to users, this type of approval will become more and more important. Cafazzo says they spent more money running the clinical trial than on developing the technology.

In July, the FDA announced its intentions to regulate smart-phone apps that are used as an accessory to a medical device already regulated by the FDA, or that use attachments, sensors, or other devices to transform the phone into a medical device.

Cafazzo's team plans to create a similar app for kids with asthma. He also hopes to collaborate with a company to commercialize the two existing apps. A limited version of the diabetes-monitoring app is currently available in the Apple app store; it doesn't include automated blood-sugar monitoring but encourages users to test themselves regularly.

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Stem-Cell Engineering Offers a Lifeline to Endangered Species

Back from beyond: Scientists have created stem cells from frozen skin samples of the endangered northern white rhinoceros.
Credit: San Diego Zoo

BIOMEDICINE

Stem-Cell Engineering Offers a Lifeline to Endangered Species

A technology used to develop new medical treatments might one day revive endangered or extinct species.

• BY EMILY SINGER

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In 1972, a group of forward-thinking conservationists in San Diego began freezing skin samples from endangered species. The hope was that science would eventually find a way to use the cells to help revive these fragile populations.

Jeanne Loring and collaborators at Scripps Research Institute have taken a key step toward fulfilling that hope by creating stem cells from frozen skin cells of two such species—the silver-maned drill monkey and the northern white rhinoceros.

In the near term, the researchers plan to build a frozen zoo of stem cells that scientists can use to study the animals' genomes, and perhaps to create stem-cell therapies for the animals. (Drill monkeys living in captivity often suffer from diabetes, a highly active area of research in the human stem-cell field.)

In the longer term, the researchers hope to be able to use the cells to create sperm and eggs, which would be incorporated into breeding programs to boost the genetic diversity of severely limited populations; the white rhinoceros is on the verge of extinction, with only seven animals alive today. They haven't bred in years.

"To think of the foresight they had in the 1970s to start this program," says Loring, director of the Center for Regenerative Medicine at Scripps. At that point, "no genome had been published, and the concept of this ever happening was science fiction." Her team aims to generate stem cells for at least 10 other species, including snow leopards and some species of elephants. San Diego's "Frozen Zoo" houses tissue samples from more than 800 species.

To create the stem cells, Inbar Friedrich Ben, a postdoctoral researcher in Loring's lab, used a technique first developed in 2007 called induced pluripotent stem (iPS) cell reprogramming. A handful of genes that are normally active in the developing embryo are expressed in a differentiated cell, such as a skin cell, causing that cell to revert back to its undifferentiated state.

Much to their surprise, the human genes that are typically used to reprogram human cells could also reprogram skin cells from both the monkey and the rhinoceros, though at a much lower efficiency. Still, the reprogrammed cells showed the defining characteristics of induced pluripotent stem cells; they could both differentiate into various cell types and generate more of themselves. The research was published this week in Nature Methods.

"This method paves the way to save endangered species such as the giant pandas, cheetahs, tigers, gorillas in East Africa, and even extinct species like the [now extinct] bucardo mountain goat," says Robert Lanza, chief scientific officer at Advanced Cell Technology. "It will open the way for new strategies to help maintain biodiversity and to respond to the challenges of large-scale extinctions ahead." Lanza was not involved in the study.

For animals like the white rhinoceros, each death represents a serious loss to the gene pool, which in turn weakens the population. By creating stem cells from animals that died, "their genes could be reintroduced to maintain the survival and genetic diversity of the species," says Lanza. "The bucardo mountain goat could be resurrected using this technology if combined with an ordinary goat breeding program."

Creating a new animal from a stem cell is likely a long way off. Researchers would need to first create sperm or eggs from the stem cells and then use them with sperm or eggs from a living animal to create an embryo. Fertility scientists are avidly searching for ways to develop sperm and eggs from stem cells in order to treat human infertility, and Loring hopes those technologies could be applied to these animals.

Prior to the development of iPS cell reprogramming, Lanza's group used cloning—the method used to create Dolly the sheep—to try to reproduce two species of wild cattle; the guar and the critically endangered banteng. But cloning is ill-suited to species conservation, since it is a technically challenging process that often results in sick or deformed animals.

Lanza says another way to use stem cells to propogate endangered species would be to inject the cells of a more common, related species into the embryo, and then use various experimental techniques to coax the cells descended from the endangered animal to grow into a fetus. His team has shown this approach works in mice.