Harvard creates cyborg flesh that’s half man, half machine

Bioengineers at Harvard University have created the first examples of cyborg tissue: Neurons, heart cells, muscle, and blood vessels that are interwoven by nanowires and transistors.

These cyborg tissues are half living cells, half electronics. As far as the cells are concerned, they’re just normal cells that behave normally — but the electronic side actually acts as a sensor network, allowing a computer to interface directly with the cells. In the case of cyborg heart tissue, the researchers have already used the embedded nanowires to measure the contractions (heart rate) of the cells.

To create cyborg flesh, you start with a three-dimensional scaffold that encourages cells to grow around them. These scaffolds are generally made of collagen, which makes up the connective tissue in almost every animal. The Harvard engineers basically took normal collagen, and wove nanowires and transistors into the matrix to create nanoelectric scaffolds (nanoES). The neurons, heart cells, muscle, and blood vessels were then grown as normal, creating cyborg tissue with a built-in sensor network.

Cardiac cells, with a nanoelectroic electrode highlighted

So far the Havard team has mostly grown rat tissues, but they have also succeeded in growing a 1.5-centimeter (0.6in) cyborg human blood vessel. They’ve also only used the nanoelectric scaffolds to read data from the cells — but according to lead researcherCharles Lieber, the next step is to find a way of talking to the individual cells, to “wire up tissue and communicate with it in the same way a biological system does.”

A computer chip, containing a sample of nanoES tissue

Suffice it to say, if you can use a digital computer to read and write data to your body’s cells, there are some awesome applications. If you need a quick jolt of adrenaline, you would simply tap a button on your smartphone, which is directly connected to your sympathetic nervous system. You could augment your existing physiology with patches — a patch of nanoelectric heart cells, for example, that integrates with your heart and reports back if you experience any problems. When we eventually put nanobots into our bloodstream, small pulses of electricity emitted by the cells could be used as guidance to damaged areas. In the case of blood vessels and other organs, the nanoelectric sensor network could detect if there’s inflammation, blockage, or tumors.

Realistically, though, we’re a long way away from such applications. In the short term, though, these cyborg tissues could be used to create very accurate organs-on-a-chip — lab-grown human organs that are encased within computer chips and then used to test drugs or substance toxicity, without harming a single bunny or bonobo.

Read: Nanotech: will it kill us all?, and Stanford’s wireless, implantable “Innerspace” medical device

Research paper: doi:10.1038/nmat3404 (paywalled)

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New nanoparticle could save lives, limit brain damage by ‘rebooting’ brain blood flow

Researchers at Rice University are conducting tests on a molecule they believe could play an important role in limiting brain damage in a wide variety of injuries. The nanoparticle, polyethylene glycol-hydrophilic carbon clusters (hereafter referred to as PEG-HCC) is already being tested as a means of enhancing certain cancer treatments. The ability to reduce/prevent brain damage, however, could be even more important.

Explaining what PEG-HCC does requires a brief discussion of reactive oxygen species (ROS) molecules. ROS molecules, including free radicals, are chemically reactive molecules that contain oxygen. The human body produces a certain number of ROS through the normal metabolization of oxygen; cells contain a variety of antioxidant enzymes specifically to neutralize ROS molecules. ROS are important to a number of processes in the human body, including apoptosis (programmed cell death) and wound repair. Platelets release ROS into the bloodstream to “recruit” platelets and leukocytes to an injury.

So long as the body remains in equilibrium and the circulatory system is functioning properly these molecules aren’t a threat. When the circulatory system stops functioning properly, that changes — and it changes quickly. Any trauma that significantly reduces blood flow to the brain, either due to stroke or major damage elsewhere, kicks off what’s known as an ischemic cascade. One of the major effects of such a cascade is the release of huge numbers of ROS molecules. Any damage to the brain’s vascular system exacerbates the problem; inadequate circulation means that local antioxidant “stockpiles” are quickly depleted.

Early stroke treatment focuses on breaking down clots precisely because restoring circulation is the only way to stop the ischemic cascade and flush the free radicals into the wider circulatory system where they can be properly broken down. One of the critical limitations of this approach, however, is that proper blood flow doesn’t automatically or instantly stop a cascade. Reperfusion, the act of restoring blood flow to a damaged area, actually leads to further damage as the body reacts to sudden concentrations of toxic byproducts released by necrosis and cell death.

The graph above shows relative levels of superoxide in an individual who suffers a traumatic brain injury (TBI) with and without low blood pressure (hypotension). Note that superoxide levels spike when blood pressure drops, fall when blood is restored and oxidation begins, but then rise considerably at the so-called “Third Strike” point. That “third strike” is the body’s wider response to the damage done by the initial cascade.

PEG-HCC doesn’t short-circuit this entire process, but it functions by neutralizing the ROS that exacerbate much of the damage. It’s far more efficient than the body’s natural defenses. SOD, the superoxide-neutralizing enzyme we naturally produce, functions on a 1:1 ratio and neutralizes one molecule at a time. One molecule of PEG-HCC is designed to neutralize hundreds of thousands of superoxide molecules.

“This is the most remarkably effective thing I’ve ever seen,” said Thomas Kent, the paper’s co-author. “Literally within minutes of injecting it, the cerebral blood flow is back to normal, and we can keep it there with just a simple second injection.”

PEG-HCC has a half-life of 2-3 hours and to date shows no signs of toxicity. Further tests are ongoing, and the nanoparticle is still years away from deployment. What this demonstrates, however, is that cutting-edge molecular biology can create medical treatments that act with far greater precision than anything we’ve deployed to date. If it works, PEG-HCC could be an extremely important tool for saving lives after an earthquake, mudslide, or building collapse. The ischemic cascade that damages brain tissue in a stroke is responsible for what’s known as crush syndrome, an extremely destructive condition that often kills individuals pinned under building rubble unless the damaged limbs are amputated swiftly.

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Living organ-on-a-chip could soon replace animal testing

If a team of Harvard bioengineers has its way, animal testing and experimentation could soon be replaced by organ-on-a-chip technologies. Like SoCs (system-on-a-chip), which shoehorn most of a digital computer into a single chip, an organ-on-a-chip seeks to replicate the functions of a human organ on a computer chip.

In Harvard’s case, its Wyss Institute has now created a living lung-on-a-chip, a heart-on-a-chip, and most recently a gut-on-a-chip.

We’re not talking about silicon chips simulating the functions of various human organs, either. These organs-on-a-chip contain real, living human cells. In the case of the gut-on-a-chip, a single layer of human intestinal cells is coerced into growing on a flexible, porous membrane, which is attached to the clear plastic walls of the chip. By applying a vacuum pump, the membrane stretches and recoils, just like a human gut going through the motions of peristalsis. It is so close to the real thing that the gut-on-a-chip even supports the growth of living microbes on its surface, like a real human intestine.

In another example, the Wyss Institute has built a lung-on-a-chip, which has human lung cells on the top, a membrane in the middle, and blood capillary cells beneath. Air flows over the top, while real human blood flows below. Again, a vacuum pump makes the lung-on-a-chip expand and contract, like a human lung.

These chips are also quite closely tied to the recent emergence of the lab-on-a-chip (LoC), which combines microfluidics (exact control of tiny amounts of fluid) and silicon technology to massively speed up the analysis of biological systems, such as DNA. It is thanks to LoCs that we can sequence entire genomes in just a few hours — a task that previously took weeks or months.

These human organs-on-a-chip can be tested just like a human subject — and the fact that they’re completely transparent is obviously a rather large boon for observation, too. To test a drug, the researchers simply add a solution of the compound to the chip, and see how the intestinal (or heart or lung) cells react. In the case of the lung-on-a-chip, the Wyss team is testing how the lung reacts to possible toxins and pollutants. They can also see how fast drugs (or foods) are absorbed, or test the effects of probiotics.

Perhaps more importantly, these chips could help us better understand and treat diseases. Many human diseases don’t have an animal analog. It’s very hard to find a drug that combats Crohn’s disease when you can’t effectively test out your drug on animals beforehand — a problem that could be easily solved with the gut-on-a-chip. Likewise, it is very common for drugs to pass animal testing, but then fail on humans. Removing animal testing from the equation would save money and time, and also alleviate any ethical concerns.

Moving forward, the Wyss Institute, with funding from DARPA, is currently researching a spleen-on-a-chip. This won’t be used for pharmaceutical purposes, though; instead, DARPA wants to create a “portable spleen” that can be inserted into soldiers to help battle sepsis (an infection of the blood).

And therein lies the crux: If you can create a chip that perfectly mimics the spleen or liver or intestine, then what’s to stop you from inserting those chips into humans and replacing or augmenting your current organs? Instead of getting your breasts enlarged, you might one day have your liver enlarged, to better deal with your alcoholism. Or how we connect all the organ chips together and create a complete human-on-a-chip?

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MIT creates glucose fuel cell to power implanted brain-computer interfaces

Neuroengineers at MIT have created a implantable fuel cell that generates electricity from the glucose present in the cerebrospinal fluid that flows around your brain and spinal cord. In theory, this fuel cell could eventually drive low-power sensors and computers that decode your brain activity to interface with prosthetic limbs.

The glucose-powered fuel cell is crafted out of silicon and platinum, using standard semiconductor fabrication processes. The platinum acts as a catalyst, stripping electrons from glucose molecules, similar to how aerobic animal cells (such as our own) strip electrons from glucose with enzymes and oxygen. The glucose fuel cell products hundreds of microwatts (i.e. tenths of a milliwatt), which is a surprisingly large amount — it’s comparable to the solar cell on a calculator, for example. This should be more than enough power to drive complex computers — or perhaps more interestingly, trigger clusters of neurons in the brain. In theory, this glucose fuel cell will actually deprive your brain of some power, though in practice you probably won’t notice (or you might find yourself growing hungry sooner…)

Size-wise, the MIT engineers have created glucose-powered fuel cells that are as large as 64x64mm (2.5in), or as small as just a few millimeters. In the picture above, the large yellow square is a single 64x64mm fuel cell, and it’s surrounded by a bunch of smaller versions. Presumably the largest fuel cell produces the most electricity — but at that size, I don’t think it would fit inside a human brain at least. You could quite easily implant a few dozen of the smallest fuel cells in your spinal cord, however.

This discovery is exciting for two main reasons: a) The fuel cell is completely synthetic, and b) they can be produced using low-tech, decades-old chip fabrication processes. Glucose fuel cells have been created before, primarily to power pacemakers, but they used biological enzymes (like your own cells) — and enzymes need to be replenished. Platinum, however, will happily strip electrons from glucose indefinitely. Platinum also has the added bonus of being very biocompatible — i.e. your immune system doesn’t try to reject it. Cerebrospinal fluid is almost entirely devoid of cells, too — it’s basically just a glucose-rich fluid that insulates your brain and spine. Because there are no cells, this means there are no white blood cells that can reject the fuel cell.

Ultimately, this fuel cell will hopefully be used to power implanted, ultra-low-power devices that sit inside your skull or spinal cord. In actual fact, MIT’s research into this fuel cell was led by Rahul Sarpeshkar, who happens to be one of the leaders of hybrid digital-biological devices. So far, implanted devices have mostly been tethered to a wall socket — but now, Sarpeshkar’s group can begin work on implants that are completely self-powered.

Now read about a brain-computer interface that bypasses paralyzed limbs, or decoding the brain to integrate a bionic eye

Read more at MIT or download the paper at PLoS ONE (non-paywalled!)

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