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3D printing

Putting 3D Printing to Work to Heal Spinal Cord Injury

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3D printed scaffold for spinal repair
Credit: Jacob Koffler and Wei Zhu, University of California, San Diego

For people whose spinal cords are injured in traffic accidents, sports mishaps, or other traumatic events, cell-based treatments have emerged as a potential avenue for encouraging healing. Now, taking advantage of advances in 3D printing technology, researchers have created customized implants that may boost the power of cell-based therapies for repairing injured spinal cords.

Made of soft hydrogels that mimic spinal cord tissue, the implant pictured here measures just 2 millimeters across and is about as thick as a penny. It was specially designed to encourage healing in rats with spinal cord injuries. The tiny, open channels that surround the solid “H”-shaped core are designed to guide the growth of new neural extensions, keeping them aligned properly with the spinal cord.

When left on their own, neural cells have a tendency to grow haphazardly. But the 3D-printed implant is engineered to act as a scaffold, keeping new cells directed toward the goal of patching up the injured part of the spinal cord.

For the new work, an NIH-funded research team, led by Jacob Koffler, Wei Zhu, Shaochen Chen, and Mark Tuszynski of the University of California, San Diego (UCSD), used an innovative 3D printing technology called microscale continuous projection printing. This technology relies on a computer projection system and precisely controlled mirrors, which direct light into a solution containing photo-sensitive polymers and cells to produce the final product. Using this approach, the researchers fabricated finely detailed, rodent-sized implants in less than 2 seconds. That’s about 1,000 times faster than a traditional 3D printer!

In a study published recently in Nature Medicine, the researchers placed their custom-made implants, loaded with rat embryonic neural stem cells, into the injured spinal cords of 11 rats. Other rats with similar injuries received empty implants or stem cells without the implant. Within 5 months, rats with the cell-loaded implants had new neural cells bridging the injured area, along with spontaneous regrowth of blood vessels to feed the new neural tissue. Most importantly, they had regained use of their hind limbs. Animals receiving empty implants or cell-based therapy without an implant didn’t show that kind of recovery.

The new findings offer proof-of-principle that 3D printing technology can be used to create implants tailored to the precise shape and size of an injury. In fact, the researchers have already scaled up the process to produce 4-centimeter-sized implants to match several different, complex spinal cord injuries in humans. These implants were printed in a mere 10 minutes.

The UCSD team continues to work on further improvements, including the addition of growth factors or other ingredients that may further encourage neuron growth and functional recovery. If all goes well, the team hopes to launch human clinical trials of their cell-based treatments for spinal cord injury within a few years. And that should provide hope for the hundreds of thousands of people around the world who suffer serious spinal cord injuries each year.


[1] Biomimetic 3D-printed scaffolds for spinal cord injury repair. Koffler J, Zhu W, Qu X, Platoshyn O, Dulin JN, Brock J, Graham L, Lu P, Sakamoto J, Marsala M, Chen S, Tuszynski MH. Nat Med. 2019 Feb;25(2):263-269.


Spinal Cord Injury Information Page (National Institute of Neurological Disorders and Stroke/NIH)

Stem Cell Information (NIH)

Koffler Lab (University of California, San Diego)

Shaochen Chen (UCSD)

Tuszynski Lab (UCSD)

NIH Support: National Institute of Biomedical Imaging and Bioengineering; National Institute of Child Health and Human Development

Taking Microfluidics to New Lengths

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Fiber Microfluidics

Caption: Microfluidic fiber sorting a solution containing either live or dead cells. The type of cell being imaged and the real time voltage (30v) is displayed at bottom. It is easy to imagine how this could be used to sort a mixture of live and dead cells. Credit: Yuan et al., PNAS

Microfluidics—the manipulation of fluids on a microscopic scale— has made it possible to produce “lab-on-a-chip” devices that detect, for instance, the presence of Ebola virus in a single drop of blood. Now, researchers hope to apply the precision of microfluidics to a much broader range of biomedical problems. Their secret? Move the microlab from chips to fibers.

To do this, an NIH-funded team builds microscopic channels into individual synthetic polymer fibers reaching 525 feet, or nearly two football fields long! As shown in this video, the team has already used such fibers to sort live cells from dead ones about 100 times faster than current methods, relying only on natural differences in the cells’ electrical properties. With further design and development, the new, fiber-based systems hold great promise for, among other things, improving kidney dialysis and detecting metastatic cancer cells in a patient’s bloodstream.

Wearable Scanner Tracks Brain Activity While Body Moves

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Credit: Wellcome Centre for Human Neuroimaging, University College London.

In recent years, researchers fueled by the BRAIN Initiative and many other NIH-supported efforts have made remarkable progress in mapping the human brain in all its amazing complexity. Now, a powerful new imaging technology promises to further transform our understanding [1]. This wearable scanner, for the first time, enables researchers to track neural activity in people in real-time as they do ordinary things—be it drinking tea, typing on a keyboard, talking to a friend, or even playing paddle ball.

This new so-called magnetoencephalography (MEG) brain scanner, which looks like a futuristic cross between a helmet and a hockey mask, is equipped with specialized “quantum” sensors. When placed directly on the scalp surface, these new MEG scanners can detect weak magnetic fields generated by electrical activity in the brain. While current brain scanners weigh in at nearly 1,000 pounds and require people to come to a special facility and remain absolutely still, the new system weighs less than 2 pounds and is capable of generating 3D images even when a person is making motions.

Building a Better Scaffold for 3D Bioprinting

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A bioprinted coronary artery

Caption: A bioprinted coronary artery.
Credit: Carnegie Mellon University

When the heart or another part of the body fails, a transplant is sometimes the only option. Still, the demand for donated organs far outpaces supply, with thousands of people on waiting lists. Furthermore, transplants currently require long term immunosuppression to prevent rejection. Wouldn’t it be even better to create the needed body part from the individual’s own cells? While it may sound too good to be true, research is moving us closer to the day when it may be possible to use 3D printing technology to meet some of this demand, as well as address a variety of other biomedical challenges.

In a study published in the journal Science Advances [1], an NIH-funded team from Carnegie Mellon University, Pittsburgh, recently modified an off-the-shelf 3D printer to create gel-like scaffolds that could be seeded with living cells to produce coronary arteries, an embryonic heart, and a variety of other tissues and organs.These researchers, of course, aren’t the only ones making progress in the rapidly emerging field of bioprinting. Using more costly, highly specialized 3D printing systems, other groups have crafted customized joints, bones, and splints out of hard, synthetic materials [2], as well as produced tissues and miniature organs by printing and layering sheets of human cells [3]. What distinguishes the new approach is its more affordable printer; its open-source software; and, perhaps most importantly, its ability to print soft, biological scaffolds that set the stage for the creation of custom-made tissues and organs with unprecedented anatomical detail.

Snapping Together a New Microlab

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Credit:  Viterbi School of Engineering, University of Southern California

Just as the computational power of yesterday’s desktop computer has been miniaturized to fit inside your mobile phone, bioengineers have shrunk traditional laboratory instruments to the size of a dime. To assemble a “snap lab” like the one you see above, all scientists have to do is click together some plastic components in much the same way that kids snap together the plastic bricks in their toy building sets.

The snap lab, developed by an NIH-funded team led by Noah Malmstadt at the University of Southern California (USC) Viterbi School of Engineering, Los Angeles, is an exciting example of a microfluidic circuit—tiny devices designed  to test just a single drop of blood, saliva, or other fluids. Such devices have the potential to make DNA analysis, microbe detection, and other biomedical tests easier and cheaper to perform.