Tag Archives: ear

Feasibility of printing ear, bone, and muscle structures

Over ten years ago I attended a show at the Vancouver (Canada) Art Gallery titled ‘Massive Change’ where I saw part of a nose or ear being grown in a petri dish (the work was from an Israeli laboratory) and that was my introduction to tissue engineering. For anyone who’s been following the tissue engineering story, 3D printers have sped up the growth process considerably. More recently, researchers at Wake Forest Baptist Medical Center (North Carolina, US) have announced another step forward for growing organs and body parts, from a Feb. 15, 2016 Wake Forest Baptist Medical Center news release on EurekAlert,

Using a sophisticated, custom-designed 3D printer, regenerative medicine scientists at Wake Forest Baptist Medical Center have proved that it is feasible to print living tissue structures to replace injured or diseased tissue in patients.

Reporting in Nature Biotechnology, the scientists said they printed ear, bone and muscle structures. When implanted in animals, the structures matured into functional tissue and developed a system of blood vessels. Most importantly, these early results indicate that the structures have the right size, strength and function for use in humans.

“This novel tissue and organ printer is an important advance in our quest to make replacement tissue for patients,” said Anthony Atala, M.D., director of the Wake Forest Institute for Regenerative Medicine (WFIRM) and senior author on the study. “It can fabricate stable, human-scale tissue of any shape. With further development, this technology could potentially be used to print living tissue and organ structures for surgical implantation.”

With funding from the Armed Forces Institute of Regenerative Medicine, a federally funded effort to apply regenerative medicine to battlefield injuries, Atala’s team aims to implant bioprinted muscle, cartilage and bone in patients in the future.

Tissue engineering is a science that aims to grow replacement tissues and organs in the laboratory to help solve the shortage of donated tissue available for transplants. The precision of 3D printing makes it a promising method for replicating the body’s complex tissues and organs. However, current printers based on jetting, extrusion and laser-induced forward transfer cannot produce structures with sufficient size or strength to implant in the body.

The Integrated Tissue and Organ Printing System (ITOP), developed over a 10-year period by scientists at the Institute for Regenerative Medicine, overcomes these challenges. The system deposits both bio-degradable, plastic-like materials to form the tissue “shape” and water-based gels that contain the cells. In addition, a strong, temporary outer structure is formed. The printing process does not harm the cells.

A major challenge of tissue engineering is ensuring that implanted structures live long enough to integrate with the body. The Wake Forest Baptist scientists addressed this in two ways. They optimized the water-based “ink” that holds the cells so that it promotes cell health and growth and they printed a lattice of micro-channels throughout the structures. These channels allow nutrients and oxygen from the body to diffuse into the structures and keep them live while they develop a system of blood vessels.

It has been previously shown that tissue structures without ready-made blood vessels must be smaller than 200 microns (0.007 inches) for cells to survive. In these studies, a baby-sized ear structure (1.5 inches) survived and showed signs of vascularization at one and two months after implantation.

“Our results indicate that the bio-ink combination we used, combined with the micro-channels, provides the right environment to keep the cells alive and to support cell and tissue growth,” said Atala.

Another advantage of the ITOP system is its ability to use data from CT and MRI scans to “tailor-make” tissue for patients. For a patient missing an ear, for example, the system could print a matching structure.

Several proof-of-concept experiments demonstrated the capabilities of ITOP. To show that ITOP can generate complex 3D structures, printed, human-sized external ears were implanted under the skin of mice. Two months later, the shape of the implanted ear was well-maintained and cartilage tissue and blood vessels had formed.

To demonstrate the ITOP can generate organized soft tissue structures, printed muscle tissue was implanted in rats. After two weeks, tests confirmed that the muscle was robust enough to maintain its structural characteristics, become vascularized and induce nerve formation.

And, to show that construction of a human-sized bone structure, jaw bone fragments were printed using human stem cells. The fragments were the size and shape needed for facial reconstruction in humans. To study the maturation of bioprinted bone in the body, printed segments of skull bone were implanted in rats. After five months, the bioprinted structures had formed vascularized bone tissue.

Ongoing studies will measure longer-term outcomes.

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The research was supported, in part, by grants from the Armed Forces Institute of Regenerative Medicine (W81XWH-08-2-0032), the Telemedicine and Advanced Technology Research Center at the U.S. Army Medical Research and Material Command (W81XWH-07-1-0718) and the Defense Threat Reduction Agency (N66001-13-C-2027).

(Sometimes the information about the funding agencies is almost as interesting as the research.) Here’s a link to and a citation for the paper,

A 3D bioprinting system to produce human-scale tissue constructs with structural integrity by Hyun-Wook Kang, Sang Jin Lee, In Kap Ko, Carlos Kengla, James J Yoo, & Anthony Atala. Nature Biotechnology (2016)  doi:10.1038/nbt.3413 Published online 15 February 2016

This paper is behind a paywall.

As you can see, despite being printed, this latest ear is also spending time in a dish,

WakeBaptistEar

Courtesy: Wake Forest Baptist Medical Center

A watch that conducts sound through your body and into your ear

Apparently, you all you have to do is tap your ear to access your telephone calls. A Jan. 8, 2016 article by Mark Wilson for Fast Company describes the technology and the experience of using Samsung’s TipTalk device,

It’s not so helpful to see a call on your smartwatch when you have to pull our your phone to take it anyway. And therein lies the problem with products like the Apple Watch: They’re often not a replacement for your phone, but an intermediary to inevitably using it.

But at this year’s Consumer Electronics Show [held in Las Vegas (Nevada, US) annually (Jan. 6 – 9, 2016)], Samsung’s secret R&D lab … showed off a promising concept to fix one of the biggest problems with smartwatches. Called TipTalk, it’s technology that can send sound from your smartwatch through your arm so when you touch your finger to your ear, you can hear a call or a voicemail—no headphones required.

Engineering breakthroughs like these can be easy to dismiss as a gimmick rather than revolutionary UX [user experience], but I like TipTalk for a few reasons. First, it maps hearing UI [user interface] into a gesture that we already might use to hear to something better … . Second, it could be practical in real world use. You see a new voicemail on your watch, and without even a button press, you listen—but crucially, you still opt-in to hear the message rather than just have it play. And third, the gesture conveys to people around you that you’re occupied.

Ulrich Rozier in his Jan. 8, 2016 article for frandroid.com also raves albeit, in French,

Samsung a développé un bracelet que l’on peut utiliser sur n’importe quelle montre.

Ce bracelet vibre lorsque l’on reçoit un appel… il est ainsi possible de décrocher. Il faut ensuite positionner son doigt au niveau du pavillon de l’oreille. C’est là que la magie opère. On se retrouve à entendre des sons. Contrairement à ce que je pensais, le son ne se transmet pas par conduction osseuse, mais grâce à des vibrations envoyées à partir de votre poignet à travers votre corps. Vous pouvez l’utiliser pour prendre des appels ou pour lire vos SMS et autres messages. Et ça fonctionne.

Here’s my very rough translation,

Samsung has developed a bracelet that can worn under any watch’s band strap.

It’s the ‘bracelet’ that vibrates when you get a phone call. If you want to answer the call, reach up and tap your ear. That’s when the magic happens and sound is transmitted to your ear. Not through your bones as I thought but with vibrations transmitted by your wrist through your body. This way you can answer your calls or read SMS and other messages [?]. It works

I get sound vibration being transmitted to your ear but I don’t understand how you’d be able to read SMS or other messages.

Ear-powered batteries

According to the Nov. 7, 2012 news item on phys.org, the idea of powering batteries with vibrations from the inner ear is not new (Note: I have removed a link),

“In the past, people have thought that the space where the high potential is located is inaccessible for implantable devices, because potentially it’s very dangerous if you encroach on it,” Stankovic [Konstantina Stankovic, an otologic surgeon at MEEI {Massachusetts Eye and Ear Infirmary}]] says. “We have known for 60 years that this battery exists and that it’s really important for normal hearing, but nobody has attempted to use this battery to power useful electronics.”

Larry Hardesty’s Nov. 7, 2012 news release for the Massachusetts Institute of Technology (MIT), which originated the news item, provides more technical detail about how the researchers have reduced the risk associated with this type of  implant,

In experiments, Konstantina Stankovic, an otologic surgeon at MEEI, and HST [Harvard-MIT Division of Health Sciences and Technology] graduate student Andrew Lysaght implanted electrodes in the biological batteries in guinea pigs’ ears. Attached to the electrodes were low-power electronic devices developed by MIT’s Microsystems Technology Laboratories (MTL). After the implantation, the guinea pigs responded normally to hearing tests, and the devices were able to wirelessly transmit data about the chemical conditions of the ear to an external receiver.

The ear converts a mechanical force — the vibration of the eardrum — into an electrochemical signal that can be processed by the brain; the biological battery is the source of that signal’s current. Located in the part of the ear called the cochlea, the battery chamber is divided by a membrane, some of whose cells are specialized to pump ions. An imbalance of potassium and sodium ions on opposite sides of the membrane, together with the particular arrangement of the pumps, creates an electrical voltage.

Although the voltage is the highest in the body (outside of individual cells, at least), it’s still very low. Moreover, in order not to disrupt hearing, a device powered by the biological battery can harvest only a small fraction of its power. Low-power chips, however, are precisely the area of expertise of Anantha Chandrakasan’s group at MTL.

The MTL researchers — Chandrakasan, who heads MIT’s Department of Electrical Engineering and Computer Science; his former graduate student Patrick Mercier, who’s now an assistant professor at the University of California at San Diego; and Saurav Bandyopadhyay, a graduate student in Chandrakasan’s group — equipped their chip with an ultralow-power radio transmitter: After all, an implantable medical monitor wouldn’t be much use if there were no way to retrieve its measurements.

But while the radio is much more efficient than those found in cellphones, it still couldn’t run directly on the biological battery. So the MTL chip also includes power-conversion circuitry — like that in the boxy converters at the ends of many electronic devices’ power cables — that gradually builds up charge in a capacitor. The voltage of the biological battery fluctuates, but it would take the control circuit somewhere between 40 seconds and four minutes to amass enough charge to power the radio. The frequency of the signal was thus itself an indication of the electrochemical properties of the inner ear.

To reduce its power consumption, the control circuit had to be drastically simplified, but like the radio, it still required a higher voltage than the biological battery could provide. Once the control circuit was up and running, it could drive itself; the problem was getting it up and running.

The MTL researchers solve that problem with a one-time burst of radio waves. “In the very beginning, we need to kick-start it,” Chandrakasan says. “Once we do that, we can be self-sustaining. The control runs off the output.”

Stankovic, who still maintains an affiliation with HST, and Lysaght implanted electrodes attached to the MTL chip on both sides of the membrane in the biological battery of each guinea pig’s ear. In the experiments, the chip itself remained outside the guinea pig’s body, but it’s small enough to nestle in the cavity of the middle ear.

The researchers seem to think that this kind of device might be used as a monitor for people with hearing difficulties or balance problems or, even, to deliver therapies. Regardless of any possible future uses, we are still a long way from human clinical trials.