In MS, immune cells called T-cells treat myelin – which insulates nerves – as a foreign invader and destroy it. This disrupts nerve cell communication, causing symptoms such as numbness, paralysis and blindness.

Current therapies suppress the whole immune system. To get round this, Daniel Getts of Northwestern University in Chicago and colleagues attached myelin molecules to biodegradable nanoparticles and injected them into the bloodstream of mice with MS.

The nanoparticles are consumed by another type of immune cell – macrophages – that mistake them for harmless dying red blood cells. The team thinks the macrophages then send a message to the rest of the immune system that this particle, along with its myelin accomplice, should be tolerated.

This targeted immune response prevented relapses of MS symptoms for up to 100 days without affecting other immune pathways

Journal reference: Nature Biotechnology,

For the first time, an electrical device has been powered by the ear alone.

The team behind the technology used a natural electrochemical gradient in cells within the inner ear of a guinea pig to power a wireless transmitter for up to five hours.

The technique could one day provide an autonomous power source for brain and cochlear implants, says , an auditory neuroscientist at Harvard University Medical School in Boston, Massachusetts.

Nerve cells use the movement of positively charged sodium and potassium ions across a membrane to create an electrochemical gradient that drives neural signals. Some cells in the cochlear have the same kind of gradient, which is used to convert the mechanical force of the vibrating eardrum into electrical signals that the brain can understand.

Tiny voltage

A major challenge in tapping such electrical potential is that the voltage created is tiny – a fraction of that generated by a standard AA battery.

“We have known about DC potential in the human ear for 60 years but no one has attempted to harness it,” Stankovic says.

Now, Stankovic and her colleagues have developed an electronic chip containing several tiny, low resistance electrodes that can harness a small amount of this electrical activity without damaging hearing.

The implant was inserted into a guinea pig’s inner ear and the electrodes attached to both sides of cochlear cell membranes. Attached to the chip was a low power radio transmitter.

Guinea pig

The device needed kick-starting with a short burst of radio waves, but was then able to use the electrical gradient running across the membrane to sustain the transmitter for up to five hours. Tests showed that the guinea pig’s hearing was not affected.

The device works well for short durations but long-term use of the electrodes risks damaging the sensitive tissue inside the ear. The next step will be to make the electrodes even smaller, reducing their invasiveness.

Stankovic says that this is proof of concept that biological sources of energy exist that have not yet been fully considered. “A very futuristic view is that maybe we will be able to extract energy from individual cells using similar designs,” she says.

Journal reference: Nature Biotechnology, DOI: 10.1038/nbt.2394

Men who lose the ability to produce sperm after chemotherapy might one day be able to regain their fertility. That’s because, for the first time, infertility has been reversed in a male primate using an injection of stem cells.

Cancer drugs often work by destroying rapidly dividing cells, as these are a typical feature of cancer. Unfortunately, the drugs can also kill other rapidly dividing cells, including those that produce sperm. Some men choose to freeze sperm samples before therapy so they can use them for artificial insemination at a later date, but this is not an option for boys who have not yet reached puberty.

at the University of Pittsburgh School of Medicine in Pennsylvania may have a solution. He says that while boys don’t make sperm cells, they do possess “spermatogonial” stem cells that will eventually produce them.

To see if these stem cells could be used to restore fertility, Orwig and his team took samples of the cells from the testes of prepubescent and adult male rhesus macaques, and froze them. The monkeys were then given chemotherapy agents known to shut down sperm production. A few months later, the researchers injected each monkey’s own spermatogonial stem cells back into its testes.

Sperm production was re-established in nine of the 12 adult animals and started normally in three out of five prepubescent animals once they reached maturity. The resulting sperm were used to fertilise eggs and produce healthy embryos.

“I think this is the best option we have ever had,” says , director of Stanford University’s Center for Human Embryonic Stem Cell Research and Education in California, who wasn’t involved in the study. “I know a lot of people have thought about doing this before but no has ever been able to successfully demonstrate this in a clinical setting with a species genetically very similar to us.”

Orwig says there are some concerns that implanting stem cells could reintroduce cancer cells that may have been present in the original tissue. However, centres in the US and Europe are already banking testicular tissue for boys in the hope that new stem-cell-based therapies will become available.

“In the most optimistic scenario our research suggests a man could have his own stem cells transplanted, giving him the opportunity to have children via natural intercourse,” Orwig says. It’s not yet ready for clinical translation, he says, “but it’s an important step forward”.

Journal reference:

GIVE a friend directions, such as, “it’s across the street from a petrol station, just after a red brick building on the right…” and you can be pretty sure they’ll find what they are looking for. Robots, on the other hand, are hopeless at following such cues, because they can’t envision a perspective other than their own. But that’s about to change.

By mimicking how primates visualise an unfamiliar environment – a process called mental rotation – researchers are building a new kind of guidance system for robots.

Many species of animals perform mental rotation – a poorly understood aspect of spatial reasoning that is nonetheless an integral part of high-level cognition.

“If I tell you to turn left, you will probably ask whose left, mine or yours?” says of Georgia Institute of Technology in Atlanta, who is leading the effort to incorporate this technique into software for controlling robots. “You have to transform your frame of reference,” he says.

The team is now testing their software in a lab setting. The researchers first supply the robot with a destination – a simplified image of how objects in their environment will look from a given perspective. The robot then uses depth information from an on-board Kinect motion sensor to establish how objects look in its surroundings.

Once it has built a picture of where it is, the robot “mentally” rotates the orientation of objects to match its destination, and then plots a path. As it trundles along, it continues to take images of its surroundings and compare them to its destination, just to make sure it is on the right track. In tests, a small four-wheeled robot used this method to find its way 6 metres across a lab floor to the right spot.

It’s a humble beginning, but Arkin says it’s the first time a robot has demonstrated the ability to receive visual instructions and act on them without a map. The work will be presented in December at the in Guangzhou, China. “When the world isn’t as you expect it to be, this will help you,” he says, adding that the system could also be adapted to use speech recognition software to understand voice commands and use them to build a picture of the destination being described.

“For the first time a robot has the ability to receive visual instructions and act on them without a map”

The team’s work is taking robotic autonomy into untested waters, says , who studies cognitive robotics at the University of California, Irvine. “There has been some work with speech recognition but a robot that can take advice and apply it is a very open area,” he says.

Giving robotic vehicles the ability to interpret an outside perspective would greatly improve their ability to navigate in the absence of conventional technologies, like GPS. “We expect this to give a cognitive push to robot navigation. It moves you in the general direction you need to go and then your other systems take over,” Arkin says.

Krichmar’s group has looked at adapting cognitive processes in rats for robotic navigation. He says that trying to transfer a model of primate cognition into robots is a big challenge, because of the higher degree of complexity.

For his part, Arkin thinks his team’s work in robots will lead to a better understanding of why primates have spatial reasoning skills in the first place. “It will not only help us add perspective-taking and advice-taking applications to robots,” he says, “but also help us understand processes we humans use every day, but know very little about.”

Hot rocks

DRAINING an infected abscess on Earth is a straightforward procedure. On a spaceship travelling to the moon or Mars, it could kill everyone on board.

Blood and bodily fluids cannot be contained in zero gravity, which means there is currently no way to perform surgery in space without contaminating the cabin. This makes an extended stay problematic, says at Carnegie Mellon University in Pittsburgh, Pennsylvania.

“Based on statistical probability, there is a high likelihood of trauma or a medical emergency on a deep space mission,” he says.

Antaki is part of a team of US researchers developing an astro-surgical tool that could help.

The Aqueous Immersion Surgical System, or AISS, is a transparent box that creates a watertight seal when it is placed over a wound and pumped full of sterile saline solution, says at the University of Louisville in Kentucky.

The saline solution is held under pressure inside the AISS to prevent blood from seeping out of the wound. Airtight holes allow surgeons to access the submerged wound using handheld and orthoscopic instruments.

By varying the pressure within the AISS, the device could also be used to siphon up and recycle blood.

“You won’t have a blood bank in space, so if there is bleeding you want to save as much blood as you can,” says , also at Carnegie Mellon, who came up with the concept.

Researchers will put the system to the test aboard NASA’s zero-gravity C-9 aircraft next week in the first of several experiments planned. They will perform surgery on an artificial coronary system filled with synthetic blood to test its ability to keep blood inside the body and out of the surgeon’s field of view. Other experiments are likely to include a sub-orbital flight test, says Pantalos.

, a bioengineer at Budapest University of Technology and Economics in Hungary, says the AISS or a similar device will be an essential tool on future space flights to an asteroid, Mars or even aboard the International Space Station. ISS astronauts could soon be increasing their stay from six months to a year.

In the event of a medical emergency on board the space station, the only current option is to evacuate the astronaut back to Earth. This is not only dangerous for the patient but it is also extremely expensive, says Haidegger. Fortunately, however, no such emergency has yet occurred.

“In the event of a medical emergency on the space station, the only option is to evacuate the patient”

According to Haidegger, it will not always be necessary to have a doctor on board the spacecraft – a surgeon on Earth could assist with invasive surgical procedures via a teleoperated robot, making a hasty return to Earth unnecessary (). The new device could play a part in such space surgery.

In the short term, Pantalos says the AISS may be useful in operating theatres back on Earth – for example, for brain and spine surgery, where bleeding presents serious complications.

THE sun beats down on sand dunes and cracked red soil as we rumble through the desert in a heavy-duty pickup truck. It is monsoon season in the Navajo Nation but the scenery looks as if it never got the memo. Two decades of severe drought have left the land parched.

“It’s hard to imagine that 30 years ago this was all covered in knee-high grass,” says Kevin Black, a Native American affairs specialist for the US Bureau of Reclamation. “Clean water has become the Navajo’s most precious commodity.”

Arizona’s largest aquifer lies 120 metres beneath us, but the water is not drinkable. It’s half as salty as seawater, and found that it contains dangerous levels of uranium and arsenic.

Black says piping water from a tribe-owned purification facility to homes scattered across an area the size of West Virginia is an economic impossibility. For 80,000 Navajo, this means no running water at home.

“Piping water to homes scattered across an area the size of West Virginia is an economic impossibility”

Instead, Navajo families drive hundreds of kilometres every month to collect water. “It is called water hauling,” Black says. “It is an expensive and time-consuming journey that has become part of the Navajo way of life.”

The Bureau of Reclamation and engineers at the University of Arizona think they have come up with a way to help, by building a self-sufficient, solar-powered desalination plant.

Black points out the budding facility perched on a hill in the south-western corner of the reservation (see map). Construction began in mid-August. On completion in 2013, it will produce close to 4000 litres of clean water a day, he says. With sufficient funding, the facility could be the first of a series across the reservation. That could halve the cost of hauling water.

Wendell Ela, the project’s lead engineer, has been testing prototypes for the past year in Tucson. He says the process uses electricity from solar panels to pump contaminated water up from the aquifer and boil it.

The steam then passes through a series of membranes that filter out salt and other contaminants. As it cools, the difference in vapour pressure it creates draws more hot water vapour through the system. Purified water is then collected in an external condenser.

Although commercial desalination plants have been used in the Middle East and Australia since the early 1990s, they rely on reverse osmosis or multistage distillation – processes that are technically challenging and expensive to maintain.

By contrast, the team’s membrane desalination system is ideal for an isolated population that does not have access to an electrical grid, Ela says. It is built using simple, low-tech, off-the-shelf components. The team is aiming to build a system lasting 30 to 40 years that would require only periodic maintenance. “We had to design the system to be within the capacity and budget of the water-users,” he says.

Such reliability isn’t guaranteed, says John Lienhard, an engineer at the Massachusetts Institute of Technology, who says the technology hasn’t been around long enough to have much of a track record. And the systems cost up to $100,000 to build. But he says that should fall steeply as they gain wider adoption.

The impact on Navajo life would be profound. If the other planned desalination plants are built in the reservation, they could provide running water to tens of thousands of Navajo who have never had it.

“People always ask, ‘If it is so bad why don’t they leave?'” Black says. “My response is, ‘Who are we to question them?’ Their livelihood and culture has been intertwined with this place for thousands of years. We are trying to help them hold on to their identity in a world that is changing very fast.”

They beat like real heart cells, but the rat cardiomyocytes in a dish at Harvard University are different in one crucial way. Snaking through them are wires and transistors that spy on each cell’s electrical impulses. In future, the wires might control their behaviour too.

Versions of this souped-up, “cyborg” tissue have been created for neurons, muscle and blood vessels. They could be used to test drugs or as the basis for more biological versions of existing implants such as pacemakers. If signals can also be sent to the cells, cyborg tissue could be used in prosthetics or to create tiny robots.

“It allows one to effectively blur the boundary between electronic, inorganic systems and organic, biological ones,” says , who leads the team behind the cyborg tissue.

Artificial tissue can already be grown on three-dimensional scaffolds made of biological materials that are not electrically active. And electrical components have been added to cultured tissue before, but not integrated into its structure, so they were only able to glean information from the surface.

Electrically inflamed

Lieber’s team combined these strands of work to create electrically active scaffolds. They created 3D networks of conductive nanowires studded with silicon sensors. Crucially, the wires had to be flexible and extremely small, to avoid impeding the growth of tissue. The scaffold also contained traditional biological materials such as collagen.

The researchers were able to grow rat neurons, heart cells and muscle in these hybrid meshes. In the case of the heart cells, they started to contract just like normal cells, and the researchers used the network to read out the rate of the beats.

When they added a drug that stimulates heart cell contraction, they detected an increase in the rate, indicating the tissue was behaving like normal and that the network could sense such changes.

Lieber’s team also managed to grow an entire blood vessel about 1.5 centimetres long from human cells, with wires snaking through it. By recording electrical signals from inside and outside the vessel– something that was never possible before– the team was able to detect electrical patterns that they say could give clues to inflammation, whether tissue has undergone changes that make it prone to tumour formation or suggest impending heart disease.

Commanding cells

“You could use these things to directly measure the effects of drugs in synthetically grown human tissue without ever having to test them in an actual human being,” says Lieber’s colleague . He also envisions tissue patches that could be added to the surface of a heart, say, to monitor for problems.

, a neurobiologist at the University of Alabama, Birmingham, who was not involved in the study, suggests using the tissue to build tiny, biomimetic robots or implants that repair damaged tissue via electronic pulses.

So far, though, the researchers have only used the electrical scaffolds to record signals– they have yet to feed commands to cells. So Lieber’s next step is to add components to the nanoscaffold that could “talk” to neurons. He says the goal is to “wire up tissue and communicate with it in the same way a biological system does”.

Journal reference:

BATTERIES are going round the bend. A flexible, lithium-ion battery can fit inside the cable for your earphones so you can wear it round your neck.

Developed by a team at in South Korea, the battery is made from electrode strands coiled into a hollow core and surrounded by an outer electrode tube. It could make future gadgets lighter because they will no longer need an integrated battery. Flexible displays or wearable electronics will be less bulky too. It might mean you can wear your power source on the wrist, round your neck or any another part of the body, its creators say.

In tests, a prototype continuously operated a red LED screen and iPod Shuffle even when researchers tied the battery in a knot. Je Young Kim of Korean firm LG Chem and a co-creator of the device, says the battery can power a small MP3 player for up to 10 hours and provide 5 minutes of emergency calls from a cellphone ().

The team’s goal is to have the battery ready for mass production by 2017, for use in MP3 players or as emergency back-up power for cellphones. “This may be the first cornerstone of the wearable energy era,” says Kim.

Lingering doubts over the future of US energy security are breathing new life into a technology that has lain dormant for more than a decade.

Researchers at the US Department of Energy’s (ORNL) and Pacific Northwest National Laboratory (PNNL) have more than doubled the amount of that can be extracted from seawater using Japanese technology developed in the late 1990s.

The world’s oceans contain around 4.5 billion tons of uranium, enough fuel to power every nuclear plant on the planet for 6,500 years. The results were presented on 21 August at a meeting of the American Chemical Society in Philadelphia, Pennsylvannia.

“Our original goal was to double what the Japanese have achieved with absorption capacity,” says PNNL chemical oceanographer Gary Gill. “We have surpassed that.”

The technology Japanese researchers pioneered uses long mats of braided plastic fibres, embedded with uranium-absorbent amidoxime, to capture trace amounts of uranium in the ocean. The mats are placed 200 metres underwater to soak up uranium before being brought to the surface. They are then washed in an acidic solution that captures the radioactive metal for future refinement.

Cheaper method

To make this process more economical, ORNL chemical scientist Sheng Dai says US researchers used plastic fibres with 10 times more surface area than the Japanese design, allowing for a greater degree of absorption on a similar platform.

They tested their new design at the PNNL’s marine testing facility in Washington State. The results show the new design cuts the production costs of a kilogram of uranium extracted from seawater from $1232 to $660.

While extracting uranium from seawater is still five times more expensive than mining uranium from the Earth, the research shows that seawater uranium harvesting could be a much-needed economic backstop for the nuclear industry moving forward into the 21st century.

“A sharp spike in uranium prices in 2007 had many people scared in terms of the sustainability of the nuclear industry,” Dai says. “That was what spurred the [Department of Energy] to revisit developing the technology.”

Gill says researchers think they are maybe three years away from having prototype systems to test.

“This is very challenging technology to develop,” he says. “But it holds a lot of promise for the US in the future.”