Tag Archives: bioengineering

A transatlantic report highlighting the risks and opportunities associated with synthetic biology and bioengineering

I love e-Life, the open access journal where its editors noted that a submitted synthetic biology and bioengineering report was replete with US and UK experts (along with a European or two) but no expert input from other parts of the world. In response the authors added ‘transatlantic’ to the title. It was a good decision since it was too late to add any new experts if the authors planned to have their paper published in the foreseeable future.

I’ve commented many times here when panels of experts include only Canadian, US, UK, and, sometimes, European or Commonwealth (Australia/New Zealand) experts that we need to broaden our perspectives and now I can add: or at least acknowledge (e.g. transatlantic) that the perspectives taken are reflective of a rather narrow range of countries.

Now getting to the report, here’s more from a November 21, 2017 University of Cambridge press release,

Human genome editing, 3D-printed replacement organs and artificial photosynthesis – the field of bioengineering offers great promise for tackling the major challenges that face our society. But as a new article out today highlights, these developments provide both opportunities and risks in the short and long term.

Rapid developments in the field of synthetic biology and its associated tools and methods, including more widely available gene editing techniques, have substantially increased our capabilities for bioengineering – the application of principles and techniques from engineering to biological systems, often with the goal of addressing ‘real-world’ problems.

In a feature article published in the open access journal eLife, an international team of experts led by Dr Bonnie Wintle and Dr Christian R. Boehm from the Centre for the Study of Existential Risk at the University of Cambridge, capture perspectives of industry, innovators, scholars, and the security community in the UK and US on what they view as the major emerging issues in the field.

Dr Wintle says: “The growth of the bio-based economy offers the promise of addressing global environmental and societal challenges, but as our paper shows, it can also present new kinds of challenges and risks. The sector needs to proceed with caution to ensure we can reap the benefits safely and securely.”

The report is intended as a summary and launching point for policy makers across a range of sectors to further explore those issues that may be relevant to them.

Among the issues highlighted by the report as being most relevant over the next five years are:

Artificial photosynthesis and carbon capture for producing biofuels

If technical hurdles can be overcome, such developments might contribute to the future adoption of carbon capture systems, and provide sustainable sources of commodity chemicals and fuel.

Enhanced photosynthesis for agricultural productivity

Synthetic biology may hold the key to increasing yields on currently farmed land – and hence helping address food security – by enhancing photosynthesis and reducing pre-harvest losses, as well as reducing post-harvest and post-consumer waste.

Synthetic gene drives

Gene drives promote the inheritance of preferred genetic traits throughout a species, for example to prevent malaria-transmitting mosquitoes from breeding. However, this technology raises questions about whether it may alter ecosystems [emphasis mine], potentially even creating niches where a new disease-carrying species or new disease organism may take hold.

Human genome editing

Genome engineering technologies such as CRISPR/Cas9 offer the possibility to improve human lifespans and health. However, their implementation poses major ethical dilemmas. It is feasible that individuals or states with the financial and technological means may elect to provide strategic advantages to future generations.

Defence agency research in biological engineering

The areas of synthetic biology in which some defence agencies invest raise the risk of ‘dual-use’. For example, one programme intends to use insects to disseminate engineered plant viruses that confer traits to the target plants they feed on, with the aim of protecting crops from potential plant pathogens – but such technologies could plausibly also be used by others to harm targets.

In the next five to ten years, the authors identified areas of interest including:

Regenerative medicine: 3D printing body parts and tissue engineering

While this technology will undoubtedly ease suffering caused by traumatic injuries and a myriad of illnesses, reversing the decay associated with age is still fraught with ethical, social and economic concerns. Healthcare systems would rapidly become overburdened by the cost of replenishing body parts of citizens as they age and could lead new socioeconomic classes, as only those who can pay for such care themselves can extend their healthy years.

Microbiome-based therapies

The human microbiome is implicated in a large number of human disorders, from Parkinson’s to colon cancer, as well as metabolic conditions such as obesity and type 2 diabetes. Synthetic biology approaches could greatly accelerate the development of more effective microbiota-based therapeutics. However, there is a risk that DNA from genetically engineered microbes may spread to other microbiota in the human microbiome or into the wider environment.

Intersection of information security and bio-automation

Advancements in automation technology combined with faster and more reliable engineering techniques have resulted in the emergence of robotic ‘cloud labs’ where digital information is transformed into DNA then expressed in some target organisms. This opens the possibility of new kinds of information security threats, which could include tampering with digital DNA sequences leading to the production of harmful organisms, and sabotaging vaccine and drug production through attacks on critical DNA sequence databases or equipment.

Over the longer term, issues identified include:

New makers disrupt pharmaceutical markets

Community bio-labs and entrepreneurial startups are customizing and sharing methods and tools for biological experiments and engineering. Combined with open business models and open source technologies, this could herald opportunities for manufacturing therapies tailored to regional diseases that multinational pharmaceutical companies might not find profitable. But this raises concerns around the potential disruption of existing manufacturing markets and raw material supply chains as well as fears about inadequate regulation, less rigorous product quality control and misuse.

Platform technologies to address emerging disease pandemics

Emerging infectious diseases—such as recent Ebola and Zika virus disease outbreaks—and potential biological weapons attacks require scalable, flexible diagnosis and treatment. New technologies could enable the rapid identification and development of vaccine candidates, and plant-based antibody production systems.

Shifting ownership models in biotechnology

The rise of off-patent, generic tools and the lowering of technical barriers for engineering biology has the potential to help those in low-resource settings, benefit from developing a sustainable bioeconomy based on local needs and priorities, particularly where new advances are made open for others to build on.

Dr Jenny Molloy comments: “One theme that emerged repeatedly was that of inequality of access to the technology and its benefits. The rise of open source, off-patent tools could enable widespread sharing of knowledge within the biological engineering field and increase access to benefits for those in developing countries.”

Professor Johnathan Napier from Rothamsted Research adds: “The challenges embodied in the Sustainable Development Goals will require all manner of ideas and innovations to deliver significant outcomes. In agriculture, we are on the cusp of new paradigms for how and what we grow, and where. Demonstrating the fairness and usefulness of such approaches is crucial to ensure public acceptance and also to delivering impact in a meaningful way.”

Dr Christian R. Boehm concludes: “As these technologies emerge and develop, we must ensure public trust and acceptance. People may be willing to accept some of the benefits, such as the shift in ownership away from big business and towards more open science, and the ability to address problems that disproportionately affect the developing world, such as food security and disease. But proceeding without the appropriate safety precautions and societal consensus—whatever the public health benefits—could damage the field for many years to come.”

The research was made possible by the Centre for the Study of Existential Risk, the Synthetic Biology Strategic Research Initiative (both at the University of Cambridge), and the Future of Humanity Institute (University of Oxford). It was based on a workshop co-funded by the Templeton World Charity Foundation and the European Research Council under the European Union’s Horizon 2020 research and innovation programme.

Here’s a link to and a citation for the paper,

A transatlantic perspective on 20 emerging issues in biological engineering by Bonnie C Wintle, Christian R Boehm, Catherine Rhodes, Jennifer C Molloy, Piers Millett, Laura Adam, Rainer Breitling, Rob Carlson, Rocco Casagrande, Malcolm Dando, Robert Doubleday, Eric Drexler, Brett Edwards, Tom Ellis, Nicholas G Evans, Richard Hammond, Jim Haseloff, Linda Kahl, Todd Kuiken, Benjamin R Lichman, Colette A Matthewman, Johnathan A Napier, Seán S ÓhÉigeartaigh, Nicola J Patron, Edward Perello, Philip Shapira, Joyce Tait, Eriko Takano, William J Sutherland. eLife; 14 Nov 2017; DOI: 10.7554/eLife.30247

This paper is open access and the editors have included their notes to the authors and the authors’ response.

You may have noticed that I highlighted a portion of the text concerning synthetic gene drives. Coincidentally I ran across a November 16, 2017 article by Ed Yong for The Atlantic where the topic is discussed within the context of a project in New Zealand, ‘Predator Free 2050’ (Note: A link has been removed),

Until the 13th century, the only land mammals in New Zealand were bats. In this furless world, local birds evolved a docile temperament. Many of them, like the iconic kiwi and the giant kakapo parrot, lost their powers of flight. Gentle and grounded, they were easy prey for the rats, dogs, cats, stoats, weasels, and possums that were later introduced by humans. Between them, these predators devour more than 26 million chicks and eggs every year. They have already driven a quarter of the nation’s unique birds to extinction.

Many species now persist only in offshore islands where rats and their ilk have been successfully eradicated, or in small mainland sites like Zealandia where they are encircled by predator-proof fences. The songs in those sanctuaries are echoes of the New Zealand that was.

But perhaps, they also represent the New Zealand that could be.

In recent years, many of the country’s conservationists and residents have rallied behind Predator-Free 2050, an extraordinarily ambitious plan to save the country’s birds by eradicating its invasive predators. Native birds of prey will be unharmed, but Predator-Free 2050’s research strategy, which is released today, spells doom for rats, possums, and stoats (a large weasel). They are to die, every last one of them. No country, anywhere in the world, has managed such a task in an area that big. The largest island ever cleared of rats, Australia’s Macquarie Island, is just 50 square miles in size. New Zealand is 2,000 times bigger. But, the country has committed to fulfilling its ecological moonshot within three decades.

In 2014, Kevin Esvelt, a biologist at MIT, drew a Venn diagram that troubles him to this day. In it, he and his colleagues laid out several possible uses for gene drives—a nascent technology for spreading designer genes through groups of wild animals. Typically, a given gene has a 50-50 chance of being passed to the next generation. But gene drives turn that coin toss into a guarantee, allowing traits to zoom through populations in just a few generations. There are a few natural examples, but with CRISPR, scientists can deliberately engineer such drives.

Suppose you have a population of rats, roughly half of which are brown, and the other half white. Now, imagine there is a gene that affects each rat’s color. It comes in two forms, one leading to brown fur, and the other leading to white fur. A male with two brown copies mates with a female with two white copies, and all their offspring inherit one of each. Those offspring breed themselves, and the brown and white genes continue cascading through the generations in a 50-50 split. This is the usual story of inheritance. But you can subvert it with CRISPR, by programming the brown gene to cut its counterpart and replace it with another copy of itself. Now, the rats’ children are all brown-furred, as are their grandchildren, and soon the whole population is brown.

Forget fur. The same technique could spread an antimalarial gene through a mosquito population, or drought-resistance through crop plants. The applications are vast, but so are the risks. In theory, gene drives spread so quickly and relentlessly that they could rewrite an entire wild population, and once released, they would be hard to contain. If the concept of modifying the genes of organisms is already distasteful to some, gene drives magnify that distaste across national, continental, and perhaps even global scales.

These excerpts don’t do justice to this thought-provoking article. If you have time, I recommend reading it in its entirety  as it provides some insight into gene drives and, with some imagination on the reader’s part, the potential for the other technologies discussed in the report.

One last comment, I notice that Eric Drexler is cited as on the report’s authors. He’s familiar to me as K. Eric Drexler, the author of the book that popularized nanotechnology in the US and other countries, Engines of Creation (1986) .

A bioengineered robot hand with its own nervous system: machine/flesh and a job opening

A November 14, 2017 news item on phys.org announces a grant for a research project which will see engineered robot hands combined with regenerative medicine to imbue neuroprosthetic hands with the sense of touch,

The sense of touch is often taken for granted. For someone without a limb or hand, losing that sense of touch can be devastating. While highly sophisticated prostheses with complex moving fingers and joints are available to mimic almost every hand motion, they remain frustratingly difficult and unnatural for the user. This is largely because they lack the tactile experience that guides every movement. This void in sensation results in limited use or abandonment of these very expensive artificial devices. So why not make a prosthesis that can actually “feel” its environment?

That is exactly what an interdisciplinary team of scientists from Florida Atlantic University and the University of Utah School of Medicine aims to do. They are developing a first-of-its-kind bioengineered robotic hand that will grow and adapt to its environment. This “living” robot will have its own peripheral nervous system directly linking robotic sensors and actuators. FAU’s College of Engineering and Computer Science is leading the multidisciplinary team that has received a four-year, $1.3 million grant from the National Institute of Biomedical Imaging and Bioengineering of the [US] National Institutes of Health for a project titled “Virtual Neuroprosthesis: Restoring Autonomy to People Suffering from Neurotrauma.”

A November14, 2017 Florida Atlantic University (FAU) news release by Gisele Galoustian, which originated the news item, goes into more detail,

With expertise in robotics, bioengineering, behavioral science, nerve regeneration, electrophysiology, microfluidic devices, and orthopedic surgery, the research team is creating a living pathway from the robot’s touch sensation to the user’s brain to help amputees control the robotic hand. A neuroprosthesis platform will enable them to explore how neurons and behavior can work together to regenerate the sensation of touch in an artificial limb.

At the core of this project is a cutting-edge robotic hand and arm developed in the BioRobotics Laboratory in FAU’s College of Engineering and Computer Science. Just like human fingertips, the robotic hand is equipped with numerous sensory receptors that respond to changes in the environment. Controlled by a human, it can sense pressure changes, interpret the information it is receiving and interact with various objects. It adjusts its grip based on an object’s weight or fragility. But the real challenge is figuring out how to send that information back to the brain using living residual neural pathways to replace those that have been damaged or destroyed by trauma.

“When the peripheral nerve is cut or damaged, it uses the rich electrical activity that tactile receptors create to restore itself. We want to examine how the fingertip sensors can help damaged or severed nerves regenerate,” said Erik Engeberg, Ph.D., principal investigator, an associate professor in FAU’s Department of Ocean and Mechanical Engineering, and director of FAU’s BioRobotics Laboratory. “To accomplish this, we are going to directly connect these living nerves in vitro and then electrically stimulate them on a daily basis with sensors from the robotic hand to see how the nerves grow and regenerate while the hand is operated by limb-absent people.”

For the study, the neurons will not be kept in conventional petri dishes. Instead, they will be placed in  biocompatible microfluidic chambers that provide a nurturing environment mimicking the basic function of living cells. Sarah E. Du, Ph.D., co-principal investigator, an assistant professor in FAU’s Department of Ocean and Mechanical Engineering, and an expert in the emerging field of microfluidics, has developed these tiny customized artificial chambers with embedded micro-electrodes. The research team will be able to stimulate the neurons with electrical impulses from the robot’s hand to help regrowth after injury. They will morphologically and electrically measure in real-time how much neural tissue has been restored.

Jianning Wei, Ph.D., co-principal investigator, an associate professor of biomedical science in FAU’s Charles E. Schmidt College of Medicine, and an expert in neural damage and regeneration, will prepare the neurons in vitro, observe them grow and see how they fare and regenerate in the aftermath of injury. This “virtual” method will give the research team multiple opportunities to test and retest the nerves without any harm to subjects.

Using an electroencephalogram (EEG) to detect electrical activity in the brain, Emmanuelle Tognoli, Ph.D., co-principal investigator, associate research professor in FAU’s Center for Complex Systems and Brain Sciences in the Charles E. Schmidt College of Science, and an expert in electrophysiology and neural, behavioral, and cognitive sciences, will examine how the tactile information from the robotic sensors is passed onto the brain to distinguish scenarios with successful or unsuccessful functional restoration of the sense of touch. Her objective: to understand how behavior helps nerve regeneration and how this nerve regeneration helps the behavior.

Once the nerve impulses from the robot’s tactile sensors have gone through the microfluidic chamber, they are sent back to the human user manipulating the robotic hand. This is done with a special device that converts the signals coming from the microfluidic chambers into a controllable pressure at a cuff placed on the remaining portion of the amputated person’s arm. Users will know if they are squeezing the object too hard or if they are losing their grip.

Engeberg also is working with Douglas T. Hutchinson, M.D., co-principal investigator and a professor in the Department of Orthopedics at the University of Utah School of Medicine, who specializes in hand and orthopedic surgery. They are developing a set of tasks and behavioral neural indicators of performance that will ultimately reveal how to promote a healthy sensation of touch in amputees and limb-absent people using robotic devices. The research team also is seeking a post-doctoral researcher with multi-disciplinary experience to work on this breakthrough project.

Here’s more about the job opportunity from the FAU BioRobotics Laboratory job posting, (I checked on January 30, 2018 and it seems applications are still being accepted.)

Post-doctoral Opportunity

Dated Posted: Oct. 13, 2017

The BioRobotics Lab at Florida Atlantic University (FAU) invites applications for a NIH NIBIB-funded Postdoctoral position to develop a Virtual Neuroprosthesis aimed at providing a sense of touch in amputees and limb-absent people.

Candidates should have a Ph.D. in one of the following degrees: mechanical engineering, electrical engineering, biomedical engineering, bioengineering or related, with interest and/or experience in transdisciplinary work at the intersection of robotic hands, biology, and biomedical systems. Prior experience in the neural field will be considered an advantage, though not a necessity. Underrepresented minorities and women are warmly encouraged to apply.

The postdoctoral researcher will be co-advised across the department of Mechanical Engineering and the Center for Complex Systems & Brain Sciences through an interdisciplinary team whose expertise spans Robotics, Microfluidics, Behavioral and Clinical Neuroscience and Orthopedic Surgery.

The position will be for one year with a possibility of extension based on performance. Salary will be commensurate with experience and qualifications. Review of applications will begin immediately and continue until the position is filled.

The application should include:

  1. a cover letter with research interests and experiences,
  2. a CV, and
  3. names and contact information for three professional references.

Qualified candidates can contact Erik Engeberg, Ph.D., Associate Professor, in the FAU Department of Ocean and Mechanical Engineering at eengeberg@fau.edu. Please reference AcademicKeys.com in your cover letter when applying for or inquiring about this job announcement.

You can find the apply button on this page. Good luck!

Prawn (shrimp) shopping bags and saving the earth

Using a material (shrimp shells) that is disposed of as waste to create a biodegradable product (shopping bags) can only be described as a major win. A Jan. 10, 2017 news item on Nanowerk makes the announcement,

Bioengineers at The University of Nottingham are trialling how to use shrimp shells to make biodegradable shopping bags, as a ‘green’ alternative to oil-based plastic, and as a new food packaging material to extend product shelf life.

The new material for these affordable ‘eco-friendly’ bags is being optimised for Egyptian conditions, as effective waste management is one of the country’s biggest challenges.

An expert in testing the properties of materials, Dr Nicola Everitt from the Faculty of Engineering at Nottingham, is leading the research together with academics at Nile University in Egypt.

“Non-degradable plastic packaging is causing environmental and public health problems in Egypt, including contamination of water supplies which particularly affects living conditions of the poor,” explains Dr Everitt.

Natural biopolymer products made from plant materials are a ‘green’ alternative growing in popularity, but with competition for land with food crops, it is not a viable solution in Egypt.

A Jan. 10, 2017 University of Nottingham press release, which originated the news item,expands on the theme,

This new project aims to turn shrimp shells, which are a part of the country’s waste problem into part of the solution.

Dr Everitt said: “Use of a degradable biopolymer made of prawn shells for carrier bags would lead to lower carbon emissions and reduce food and packaging waste accumulating in the streets or at illegal dump sites. It could also make exports more acceptable to a foreign market within a 10-15-year time frame. All priorities at a national level in Egypt.”

Degradable nanocomposite material

The research is being undertaken to produce an innovative biopolymer nanocomposite material which is degradable, affordable and suitable for shopping bags and food packaging.

Chitosan is a man-made polymer derived from the organic compound chitin, which is extracted from shrimp shells, first using acid (to remove the calcium carbonate “backbone” of the crustacean shell) and then alkali (to produce the long molecular chains which make up the biopolymer).

The dried chitosan flakes can then be dissolved into solution and polymer film made by conventional processing techniques.

Chitosan was chosen because it is a promising biodegradable polymer already used in pharmaceutical packaging due to its antimicrobial, antibacterial and biocompatible properties. The second strand of the project is to develop an active polymer film that absorbs oxygen.

Enhancing food shelf life and cutting food waste

This future generation food packaging could have the ability to enhance food shelf life with high efficiency and low energy consumption, making a positive impact on food wastage in many countries.

If successful, Dr Everitt plans to approach UK packaging manufacturers with the product.

Additionally, the research aims to identify a production route by which these degradable biopolymer materials for shopping bags and food packaging could be manufactured.

I also found the funding for this project to be of interest (from the press release),

The project is sponsored by the Newton Fund and the Newton-Mosharafa Fund grant and is one of 13 Newton-funded collaborations for The University of Nottingham.

The collaborations, which are designed to tackle community issues through science and innovation, with links formed with countries such as Brazil, Egypt, Philippines and Indonesia.

Since the Newton Fund was established in 2014, the University has been awarded a total of £4.5m in funding. It also boasts the highest number of institutional-led collaborations.

Professor Nick Miles Pro-Vice-Chancellor for Global Engagement said: “The University of Nottingham has a long and established record in global collaboration and research.

The Newton Fund plays to these strengths and enables us to work with institutions around the world to solve some of the most pressing issues facing communities.”

From a total of 68 universities, The University of Nottingham has emerged as the top awardee of British Council Newton Fund Institutional Links grants (13) and is joint top awardee from a total of 160 institutions competing for British Council Newton Fund Researcher Links Workshop awards (6).

Professor Miles added: “This is testament to the incredible research taking place across the University – both here in the UK and in the campuses in Malaysia and China – and underlines the strength of our research partnerships around the world.”

That’s it!

Better technique for growing organoids taking them from the lab to the clinic

A Nov. 16, 2016 École Polytechnique Fédérale de Lausanne (EPFL) press release (also on EurekAlert) describes a new material for growing organoids,

Organoids are miniature organs that can be grown in the lab from a person’s stem cells. They can be used to model diseases, and in the future could be used to test drugs or even replace damaged tissue in patients. But currently organoids are very difficult to grow in a standardized and controlled way, which is key to designing and using them. EPFL scientists have now solved the problem by developing a patent-pending “hydrogel” that provides a fully controllable and tunable way to grow organoids. …

Organoids need a 3D scaffold

Growing organoids begins with stem cells — immature cells that can grow into any cell type of the human body and that play key roles in tissue function and regeneration. To form an organoid, the stem cells are grown inside three-dimensional gels that contain a mix of biomolecules that promote stem cell renewal and differentiation.

The role of these gels is to mimic the natural environment of the stem cells, which provides them with a protein- and sugar-rich scaffold called the “extracellular matrix”, upon which the stem cells build specific body tissues. The stem cells stick to the extracellular matrix gel, and then “self-organize” into miniature organs like retinas, kidneys, or the gut. These tiny organs retain key aspects of their real-life biology, and can be used to study diseases or test drugs before moving on to human trials.

But the current gels used for organoid growth are derived from mice, and have problems. First, it is impossible to control their makeup from batch to batch, which can cause stem cells to behave inconsistently. Second, their biochemical complexity makes them very difficult to fine-tune for studying the effect of different parameters (e.g. biological molecules, mechanical properties, etc.) on the growth of organoids. Finally, the gels can carry pathogens or immunogens, which means that they are not suitable for growing organoids to be used in the clinic.

A hydrogel solution

The lab of Matthias Lütolf at EPFL’s Institute of Bioengineering has developed a synthetic “hydrogel” that eschews the limitations of conventional, naturally derived gels. The patent-pending gel is made of water and polyethylene glycol, a substance used widely today in various forms, from skin creams and toothpastes to industrial applications and, as in this case, bioengineering.

Nikolce Gjorevski, the first author of the study, and his colleagues used the hydrogel to grow stem cells of the gut into a miniature intestine. The functional hydrogel was not only a goal in and of itself, but also a means to identify the factors that influence the stem cells’ ability to expand and form organoids. By carefully tweaking the hydrogel’s properties, they discovered that separate stages of the organoid formation process require different mechanical environments and biological components.

One such factor is a protein called fibronectin, which helps the stem cells attach to the hydrogel. Lütolf’s lab found that this attachment itself is immensely important for growing organoids, as it triggers a whole host of signals to the stem cell that tell it to grow and build an intestine-like structure. The researchers also discovered an essential role for the mechanical properties, i.e. the physical stiffness, of the gel in regulating intestinal stem cell behavior, shedding light on how cells are able to sense, process and respond to physical stimuli. This insight is particularly valuable – while the influence of biochemical signals on stem cells is well-understood, the effect of physical factors has been more mysterious.

Because the hydrogel is man-made, it is easy to control its chemical composition and key properties, and ensure consistency from batch to batch. And because it is artificial, it does not carry any risk of infection or triggering immune responses. As such, it provides a means of moving organoids from basic research to actual pharmaceutical and clinical applications in the future.

Lütolf’s lab is now researching other types of stem cells in order to extend the capacities of their hydrogel into other tissues.

Here’s a link to and a citation for the paper,

Designer matrices for intestinal stem cell and organoid culture by Nikolce Gjorevski, Norman Sachs, Andrea Manfrin, Sonja Giger, Maiia E. Bragina, Paloma Ordóñez-Morán, Hans Clevers, & Matthias P. Lutolf.  Nature (2016) doi:10.1038/nature20168 Published online 16 November 2016

This paper is behind a paywall.

Brain and machine as one (machine/flesh)

The essay on brains and machines becoming intertwined is making the rounds. First stop on my tour was its Oct. 4, 2016 appearance on the Mail & Guardian, then there was its Oct. 3, 2016 appearance on The Conversation, and finally (moving forward in time) there was its Oct. 4, 2016 appearance on the World Economic Forum website as part of their Final Frontier series.

The essay was written by Richard Jones of Sheffield University (mentioned here many times before but most recently in a Sept. 4, 2014 posting). His book ‘Soft Machines’ provided me with an important and eminently readable introduction to nanotechnology. He is a professor of physics at the University of Sheffield and here’s more from his essay (Oct. 3, 2016 on The Conversation) about brains and machines (Note: Links have been removed),

Imagine a condition that leaves you fully conscious, but unable to move or communicate, as some victims of severe strokes or other neurological damage experience. This is locked-in syndrome, when the outward connections from the brain to the rest of the world are severed. Technology is beginning to promise ways of remaking these connections, but is it our ingenuity or the brain’s that is making it happen?

Ever since an 18th-century biologist called Luigi Galvani made a dead frog twitch we have known that there is a connection between electricity and the operation of the nervous system. We now know that the signals in neurons in the brain are propagated as pulses of electrical potential, whose effects can be detected by electrodes in close proximity. So in principle, we should be able to build an outward neural interface system – that is to say, a device that turns thought into action.

In fact, we already have the first outward neural interface system to be tested in humans. It is called BrainGate and consists of an array of micro-electrodes, implanted into the part of the brain concerned with controlling arm movements. Signals from the micro-electrodes are decoded and used to control the movement of a cursor on a screen, or the motion of a robotic arm.

A crucial feature of these systems is the need for some kind of feedback. A patient must be able to see the effect of their willed patterns of thought on the movement of the cursor. What’s remarkable is the ability of the brain to adapt to these artificial systems, learning to control them better.

You can find out more about BrainGate in my May 17, 2012 posting which also features a video of a woman controlling a mechanical arm so she can drink from a cup coffee by herself for the first time in 15 years.

Jones goes on to describe the cochlear implants (although there’s no mention of the controversy; not everyone believes they’re a good idea) and retinal implants that are currently available. Jones notes this (Note Links have been removed),

The key message of all this is that brain interfaces now are a reality and that the current versions will undoubtedly be improved. In the near future, for many deaf and blind people, for people with severe disabilities – including, perhaps, locked-in syndrome – there are very real prospects that some of their lost capabilities might be at least partially restored.

Until then, our current neural interface systems are very crude. One problem is size; the micro-electrodes in use now, with diameters of tens of microns, may seem tiny, but they are still coarse compared to the sub-micron dimensions of individual nerve fibres. And there is a problem of scale. The BrainGate system, for example, consists of 100 micro-electrodes in a square array; compare that to the many tens of billions of neurons in the brain. The fact these devices work at all is perhaps more a testament to the adaptability of the human brain than to our technological prowess.

Scale models

So the challenge is to build neural interfaces on scales that better match the structures of biology. Here, we move into the world of nanotechnology. There has been much work in the laboratory to make nano-electronic structures small enough to read out the activity of a single neuron. In the 1990s, Peter Fromherz, at the Max Planck Institute for Biochemistry, was a pioneer of using silicon field effect transistors, similar to those used in commercial microprocessors, to interact with cultured neurons. In 2006, Charles Lieber’s group at Harvard succeeded in using transistors made from single carbon nanotubes – whiskers of carbon just one nanometer in diameter – to measure the propagation of single nerve pulses along the nerve fibres.

But these successes have been achieved, not in whole organisms, but in cultured nerve cells which are typically on something like the surface of a silicon wafer. It’s going to be a challenge to extend these methods into three dimensions, to interface with a living brain. Perhaps the most promising direction will be to create a 3D “scaffold” incorporating nano-electronics, and then to persuade growing nerve cells to infiltrate it to create what would in effect be cyborg tissue – living cells and inorganic electronics intimately mixed.

I have featured Charles Lieber and his work here in two recent posts: ‘Bionic’ cardiac patch with nanoelectric scaffolds and living cells on July 11, 2016 and Long-term brain mapping with injectable electronics on Sept. 22, 2016.

For anyone interested in more about the controversy regarding cochlear implants, there’s this page on the Brown University (US) website. You might also want to check out Gregor Wolbring (professor at the University of Calgary) who has written extensively on the concept of ableism (links to his work can be found at the end of this post). I have excerpted from an Aug. 30, 2011 post the portion where Gregor defines ‘ableism’,

From Gregor’s June 17, 2011 posting on the FedCan blog,

The term ableism evolved from the disabled people rights movements in the United States and Britain during the 1960s and 1970s.  It questions and highlights the prejudice and discrimination experienced by persons whose body structure and ability functioning were labelled as ‘impaired’ as sub species-typical. Ableism of this flavor is a set of beliefs, processes and practices, which favors species-typical normative body structure based abilities. It labels ‘sub-normative’ species-typical biological structures as ‘deficient’, as not able to perform as expected.

The disabled people rights discourse and disability studies scholars question the assumption of deficiency intrinsic to ‘below the norm’ labeled body abilities and the favoritism for normative species-typical body abilities. The discourse around deafness and Deaf Culture would be one example where many hearing people expect the ability to hear. This expectation leads them to see deafness as a deficiency to be treated through medical means. In contrast, many Deaf people see hearing as an irrelevant ability and do not perceive themselves as ill and in need of gaining the ability to hear. Within the disabled people rights framework ableism was set up as a term to be used like sexism and racism to highlight unjust and inequitable treatment.

Ableism is, however, much more pervasive.

You can find out more about Gregor and his work here: http://www.crds.org/research/faculty/Gregor_Wolbring2.shtml or here:

Cutting into a cell with a nanoblade

A May 11, 2016 news item on Nanotechnology Now features a type of surgery that could aid in cell engineering,

To study certain aspects of cells, researchers need the ability to take the innards out, manipulate them, and put them back. Options for this kind of work are limited, but researchers reporting May 10 [2016] in Cell Metabolism describe a “nanoblade” that can slice through a cell’s membrane to insert mitochondria. The researchers have previously used this technology to transfer other materials between cells and hope to commercialize the nanoblade for wider use in bioengineering.

Caption: This diagram illustrates the process of transferring mitochondria between cells using the nanoblade technology. Credit: Alexander N. Patananan Courtesy UCLA

Caption: This diagram illustrates the process of transferring mitochondria between cells using the nanoblade technology.
Credit: Alexander N. Patananan Courtesy UCLA

A May 10, 2016 Cell Press news release on EurekAlert, which originated the news item, expands on the theme,

“As a new tool for cell engineering, to truly engineer cells for health purposes and research, I think this is very unique,” says Mike Teitell, a pathologist and bioengineer at the University of California, Los Angeles (UCLA). “We haven’t run into anything so far, up to a few microns in size, that we can’t deliver.”

Teitell and Pei-Yu “Eric” Chiou, also a bioengineer at UCLA, first conceived the idea of a nanoblade several years ago to transfer a nucleus from one cell to another. However, they soon delved into the intersection of stem cell biology and energy metabolism, where the technology could be used to manipulate a cell’s mitochondria. Studying the effects of mutations in the mitochondrial genome, which can cause debilitating or fatal diseases in humans, is tricky for a number of reasons.

“There’s a bottleneck in the field for modifying a cell’s mitochondrial DNA,” says Teitell. “So we are working on a two-step process: edit the mitochondrial genome outside of a cell, and then take those manipulated mitochondria and put them back into the cell. We’re still working on the first step, but we’ve solved that second one quite well.”

The nanoblade apparatus consists of a microscope, laser, and titanium-coated micropipette to act as the “blade,” operated using a joystick controller. When a laser pulse strikes the titanium, the metal heats up, vaporizing the surrounding water layers in the culture media and forming a bubble next to a cell. Within a microsecond, the bubble expands, generating a local force that punctures the cell membrane and creates a passageway several microns long that the “cargo”–in this case, mitochondria–can be pushed through. The cell then rapidly repairs the membrane defect.

Teitell, Chiou, and their team used the nanoblade to insert tagged mitochondria from human breast cancer cells and embryonic kidney cells into cells without mitochondrial DNA. When they sequenced the nuclear and mitochondrial DNA afterwards, the researchers saw that the mitochondria had been successfully transferred and replicated by 2% of the cells, with a range of functionality. Other methods of mitochondrial transfer are hard to control, and when they have been reported to work, the success rates have been only 0.0001%-0.5% according to the researchers.

“The success of the mitochondrial transfer was very encouraging,” says Chiou. “The most exciting application for the nanoblade, to me, is in the study of mitochondria and infectious diseases. This technology brings new capabilities to help advance these fields.”

The team’s aspirations also go well beyond mitochondria, and they’ve already scaled up the nanoblade apparatus into an automated high-throughput version. “We want to make a platform that’s easy to use for everyone and allow researchers to devise anything they can think of a few microns or smaller that would be helpful for their research–whether that’s inserting antibodies, pathogens, synthetic materials, or something else that we haven’t imagined,” says Teitell. “It would be very cool to allow people to do something that they can’t do right now.”

The pipette being used is measured at the microscale but it’s called a nanoblade? Well, perhaps the tip or the edge of the pipette is measured at the nanoscale.

Getting back to the research, here’s a link to and a citation for the paper,

Mitochondrial Transfer by Photothermal Nanoblade Restores Metabolite Profile in Mammalian Cells by Ting-Hsiang Wu, Enrico Sagullo, Dana Case, Xin Zheng, Yanjing Li, Jason S. Hong, Tara TeSlaa, Alexander N. Patananan, J. Michael McCaffery, Kayvan Niazi, Daniel Braas, Carla M. Koehler, Thomas G. Graeber, Pei-Yu Chiou, Michael A. Teitell. Cell Metabolism Volume 23, Issue 5, p921–929, 10 May 2016  DOI: http://dx.doi.org/10.1016/j.cmet.2016.04.007

This paper appears to be open access.

Hydrogels and cartilage; repurposing vehicles in space; big bang has ‘fingerprints’

The American Institute of Physics (AIP) has made a selection of four articles freely available (h/t Mar. 9, 2015 news item on Azonano).

From a March 6, 2015 AIP news release,

WASHINGTON D.C., March 6, 2015 — The following articles are freely available online from Physics Today (www.physicstoday.org), the world’s most influential and closely followed magazine devoted to physics and the physical science community.

You are invited to read, share, blog about, link to, or otherwise enjoy:


Physics Today‘s Ashley Smart reports on hydrogels that mimic the tricky nature of cartilage thanks to magnetically aligned nanosheets.

“In the realm of bioengineering, hydrogels are something of an all-purpose material. Made up of networks of interlinked, hydrophilic polymers, they tend to be soft, biocompatible, and highly absorbent…. The new material mimics the articular cartilage that lubricates our joints: It can support a heavy load along one direction while stretching and shearing with ease in the others.”

MORE: http://dx.doi.org/10.1063/PT.3.2707


Physics Today‘s Toni Feder reports on the innovative processes undertaken to repurpose various spacecraft in flight, including Kepler, Voyager, Deep Impact, Spitzer, and the Hubble Space Telescope.

“A comeback like Kepler’s is ‘not unique, but it’s unusual,’ says Derek Buzasi of Florida Gulf Coast University, who reinvented the Wide-Field Infrared Explorer (WIRE) after it failed following its 1999 launch. ‘Spacecraft are built for a specialized purpose, so they are hard to repurpose. You have to come up with something they are capable of at the same time they are incapable of their original mission.’

Deep Impact’s original mission was to hurl a copper ball at a comet and watch the impact. In its continued form as EPOXI, the spacecraft went on to visit another comet and, on the way, served as an observatory for user- proposed targets.”

MORE: http://dx.doi.org/10.1063/PT.3.2713


Physics Today‘s David Kramer interviews Rush Holt, the New Jersey congressman who retired from office and this past December took the helm of the American Association for the Advancement of Science.

“PT: What do you consider to be your accomplishments in Congress?

HOLT: I focused a lot on science education. Our real problem is not that we’re failing to produce excellent scientists, because we are [producing them], but rather that we have failed to maintain an appreciation for and understanding of science in the general population. I was able to keep a spotlight on the need but wasn’t able to accomplish as much as I wanted. We got science included in the subjects emphasized by federal law. But we haven’t really improved teacher professional development and other things we need to do.”

MORE: http://dx.doi.org/10.1063/PT.3.2714


In this article, physics researchers John Carlstrom, Tom Crawford and Lloyd Knox discuss the fingerprints of the Big Bang and quantum fluctuations in the early universe, which may soon reveal physics at unprecedented energy scales.

“With its empirical successes, inflation is by consensus the best paradigm—notwithstanding some notable dissenting views—for the mechanism that generated the primordial density fluctuations that led to all structure in the universe. Its success has motivated physicists to search for the siblings of those fluctuations, the gravitational waves, via their signature in the polarization of the CMB. If discovered, that gravitational imprint would open up an observational window onto quantum gravitational effects, extremely early times, and extremely high energies.”

MORE: http://dx.doi.org/10.1063/PT.3.2718

I have checked; all of the links do lead to the articles.

Medical nanobots (nanorobots) and biocomputing; an important step in Russia

Russian researchers have reported a technique which can make logical calculations from within cells according to an Aug. 19, 2014 news item on ScienceDaily,

Researchers from the Institute of General Physics of the Russian Academy of Sciences, the Institute of Bioorganic Chemistry of the Russian Academy of Sciences and MIPT [Moscow Institute of Physics and Technology] have made an important step towards creating medical nanorobots. They discovered a way of enabling nano- and microparticles to produce logical calculations using a variety of biochemical reactions.

An Aug. 19 (?), 2014 MIPT press release, which originated the news item, provides a good beginner’s explanation of bioengineering in the context of this research,

For example, modern bioengineering techniques allow for making a cell illuminate with different colors or even programming it to die, linking the initiation  of apoptosis [cell death] to the result of binary operations.

Many scientists believe logical operations inside cells or in artificial biomolecular systems to be a way of controlling biological processes and creating full-fledged micro-and nano-robots, which can, for example, deliver drugs on schedule to those tissues where they are needed.

Calculations using biomolecules inside cells, a.k.a. biocomputing, are a very promising and rapidly developing branch of science, according to the leading author of the study, Maxim Nikitin, a 2010 graduate of MIPT’s Department of Biological and Medical Physics. Biocomputing uses natural cellular mechanisms. It is far more difficult, however, to do calculations outside cells, where there are no natural structures that could help carry out calculations. The new study focuses specifically on extracellular biocomputing.

The study paves the way for a number of biomedical technologies and differs significantly from previous works in biocomputing, which focus on both the outside and inside of cells. Scientists from across the globe have been researching binary operations in DNA, RNA and proteins for over a decade now, but Maxim Nikitin and his colleagues were the first to propose and experimentally confirm a method to transform almost any type of nanoparticle or microparticle into autonomous biocomputing structures that are capable of implementing a functionally complete set of Boolean logic gates (YES, NOT, AND and OR) and binding to a target (such as a cell) as result of a computation. This method allows for selective binding to target cells, as well as it represents a new platform to analyze blood and other biological materials.

The prefix “nano” in this case is not a fad or a mere formality. A decrease in particle size sometimes leads to drastic changes in the physical and chemical properties of a substance. The smaller the size, the greater the reactivity; very small semiconductor particles, for example, may produce fluorescent light. The new research project used nanoparticles (i.e. particles of 100 nm) and microparticles (3000 nm or 3 micrometers).

Nanoparticles were coated with a special layer, which “disintegrated” in different ways when exposed to different combinations of signals. A signal here is the interaction of nanoparticles with a particular substance. For example, to implement the logical operation “AND” a spherical nanoparticle was coated with a layer of molecules, which held a layer of spheres of a smaller diameter around it. The molecules holding the outer shell were of two types, each type reacting only to a particular signal; when in contact with two different substances small spheres separated from the surface of a nanoparticle of a larger diameter. Removing the outer layer exposed the active parts of the inner particle, and it was then able to interact with its target. Thus, the team obtained one signal in response to two signals.

For bonding nanoparticles, the researchers selected antibodies. This also distinguishes their project from a number of previous studies in biocomputing, which used DNA or RNA for logical operations. These natural proteins of the immune system have a small active region, which responds only to certain molecules; the body uses the high selectivity of antibodies to recognize and neutralize bacteria and other pathogens.

Making sure that the combination of different types of nanoparticles and antibodies makes it possible to implement various kinds of logical operations, the researchers showed that cancer cells can be specifically targeted as well. The team obtained not simply nanoparticles that can bind to certain types of cells, but particles that look for target cells when both of two different conditions are met, or when two different molecules are present or absent. This additional control may come in handy for more accurate destruction of cancer cells with minimal impact on healthy tissues and organs.

Maxim Nikitin said that although this is just as mall step towards creating efficient nanobiorobots, this area of science is very interesting and opens up great vistas for further research, if one draws an analogy between the first works in the creation of nanobiocomputers and the creation of the first diodes and transistors, which resulted in the rapid development of electronic computers.

Here’s a link to and a citation for the paper,

Biocomputing based on particle disassembly by Maxim P. Nikitin, Victoria O. Shipunova, Sergey M. Deyev, & Petr I. Nikitin. Nature Nanotechnology (2014) doi:10.1038/nnano.2014.156 Published online 17 August 2014

This paper is behind a paywall.

Growing a tooth—as an adult

These days it seems that teeth are the most erogenous zone of all. Actors on screens of all types flash pearly whites that are increasingly blinding while the rest of us are enjoined to buy teeth whiteners in toothpastes, mouthwashes, whitening strips, and/or find dental professionals to assist us in our quest for the brightest and whitest teeth. It would all be so much easier if we could just grow new teeth and discard the old ones.

Coincidentally or not, it seems researchers at King’s College London have also been thinking about how we might grow new teeth. Ben Schiller in a Mar. 14, 2013 article for Fast Company highlights the work,

Researchers from the U.K. have successfully bioengineered teeth from gum tissue and cells taken from mice. By combining and transplanting two groups of cells, they were able to grow full teeth, complete with roots, dentine, and enamel.

This King’s College London Mar. 11, 2013 news release provides more details,

New research published in the Journal of Dental Research describes an advance in efforts to develop a method to replace missing teeth with new bioengineered teeth generated from a person’s own gum cells. …

Current implant-based methods of whole tooth replacement fail to reproduce a natural root structure and as a consequence of the friction from eating and other jaw movement, loss of jaw bone can occur around the implant.

Research towards achieving the aim of producing bioengineered teeth (bioteeth) has largely focused on the generation of immature teeth (teeth primordia) that mimic those in the embryo that can be transplanted as small cell ‘pellets’ into the adult jaw to develop into functional teeth. Remarkably, despite the very different environments, embryonic teeth primordia can develop normally in the adult mouth and thus if suitable cells can be identified that can be combined in such a way to produce an immature tooth, there is a realistic prospect bioteeth can become a clinical reality. Subsequent studies have largely focussed on the use of embryonic cells and although it is clear that embryonic tooth primordia cells can readily form immature teeth following dissociation into single cell populations and subsequent recombination, such cell sources are impractical to use in a general therapy.

Professor Sharpe [Paul Sharpe, an expert in craniofacial development and stem cell biology at King’s College London’s Dental Institute] said: ‘What is required is the identification of adult sources of human epithelial and mesenchymal cells that can be obtained in sufficient numbers to make biotooth formation a viable alternative to dental implants.’

In this new work, the researchers isolated adult human gum (gingival) tissue from patients at the Dental Institute at King’s College London, grew more of it in the lab, and then combined it with the cells of mice that form teeth (mesenchyme cells). By transplanting this combination of cells into mice the researchers were able to grow hybrid human/mouse teeth containing dentine and enamel, as well as viable roots.

Professor Sharpe concluded: ‘Epithelial cells derived from adult human gum tissue are capable of responding to tooth inducing signals from embryonic tooth mesenchyme in an appropriate way to contribute to tooth crown and root formation and give rise to relevant differentiated cell types, following in vitro culture. These easily accessible epithelial cells are thus a realistic source for consideration in human biotooth formation. The next major challenge is to identify a way to culture adult human mesenchymal cells to be tooth-inducing, as at the moment we can only make embryonic mesenchymal cells do this.’

If I read this rightly, researchers are several years away from actually growing a new tooth in an adult human mouth but this work suggests they might be on the right research track.

Bioengineered ear at Cornell University

The researchers claim their bioengineered ear looks and acts like a real ear, from the Feb. 20, 2013 news release on EurekAlert,

Cornell bioengineers and physicians have created an artificial ear – using 3-D printing and injectable molds – that looks and acts like a natural ear, giving new hope to thousands of children born with a congenital deformity called microtia.

In a study published online Feb. 20 in PLOS ONE, Cornell biomedical engineers and Weill Cornell Medical College physicians described how 3-D printing and injectable gels made of living cells can fashion ears that are practically identical to a human ear. Over a three-month period, these flexible ears grew cartilage to replace the collagen that was used to mold them.

“This is such a win-win for both medicine and basic science, demonstrating what we can achieve when we work together,” said co-lead author Lawrence Bonassar, associate professor of biomedical engineering.

The novel ear may be the solution reconstructive surgeons have long wished for to help children born with ear deformity, said co-lead author Dr. Jason Spector, director of the Laboratory for Bioregenerative Medicine and Surgery and associate professor of plastic surgery at Weill Cornell in New York City.

“A bioengineered ear replacement like this would also help individuals who have lost part or all of their external ear in an accident or from cancer,” Spector said.

Replacement ears are usually constructed with materials that have a Styrofoam-like consistency, or sometimes, surgeons build ears from a patient’s harvested rib. This option is challenging and painful for children, and the ears rarely look completely natural or perform well, Spector said.

Lawrence Bonassar, associate professor of biomedical engineering, and colleagues collaborated with Weill Cornell Medical College physicians to create an artificial ear using 3-D printing and injectable molds. Credit: Lindsay France/University Photography [downloaded from http://www.news.cornell.edu/stories/Feb13/earPrint.html]

Lawrence Bonassar, associate professor of biomedical engineering, and colleagues collaborated with Weill Cornell Medical College physicians to create an artificial ear using 3-D printing and injectable molds. Credit: Lindsay France/University Photography [downloaded from http://www.news.cornell.edu/stories/Feb13/earPrint.html]

A Feb. 20, 2013 article in Cornell University’s Chronicle Online (and the basis for the news release) provides details about how this bioengineered ear was achieved (Note: A link has been removed),

To make the ears, Bonassar and colleagues started with a digitized 3-D image of a human subject’s ear and converted the image into a digitized “solid” ear using a 3-D printer to assemble a mold.

They injected the mold with collagen derived from rat tails, and then added 250 million cartilage cells from the ears of cows. This Cornell-developed, high-density gel is similar to the consistency of Jell-O when the mold is removed. The collagen served as a scaffold upon which cartilage could grow.

The process is also fast, Bonassar added: “It takes half a day to design the mold, a day or so to print it, 30 minutes to inject the gel, and we can remove the ear 15 minutes later. We trim the ear and then let it culture for several days in nourishing cell culture media before it is implanted.”

The incidence of microtia, which is when the external ear is not fully developed, varies from almost 1 to more than 4 per 10,000 births each year. Many children born with microtia have an intact inner ear, but experience hearing loss due to the missing external structure.

There was a show in 2004  at the Vancouver Art Gallery (Canada), Massive Change, curated by graphic designer Bruce Mau, which amongst many other objects and images featured a bioengineered nose being grown in a beaker. If memory serves, the work featuring the nose was from Israel and there was no mention of when that work might leave the lab and be used for implants. From the Chronicle article,

Bonassar and Spector have been collaborating on bioengineered human replacement parts since 2007. Bonassar has also worked with Weill Cornell neurological surgeon Dr. Roger Härtl on bioengineered disc replacements using some of the same techniques demonstrated in the PLOS One study.

The researchers specifically work on replacement human structures that are primarily made of cartilage — joints, trachea, spine, nose — because cartilage does not need to be vascularized with a blood supply in order to survive.

They are now looking at ways to expand populations of human ear cartilage cells in the laboratory so that these cells can be used in the mold, instead of cow cartilage.

“Using human cells, specifically those from the same patient, would reduce any possibility of rejection,” Spector said.

He added that the best time to implant a bioengineered ear on a child would be when they are about 5 or 6 years old. At that age, ears are 80 percent of their adult size.

If all future safety and efficacy tests work out, it might be possible to try the first human implant of a Cornell bioengineered ear in as little as three years, Spector said.

Good luck to them. For anyone who’s interested here’s a citation and link to the paper,

Reiffel AJ, Kafka C, Hernandez KA, Popa S, Perez JL, et al. (2013) High-Fidelity Tissue Engineering of Patient-Specific Auricles for Reconstruction of Pediatric Microtia and Other Auricular Deformities. PLoS ONE 8(2): e56506. doi:10.1371/journal.pone.0056506

PLoS One is an open access journal.