Skip to main content

spinal cord

Putting 3D Printing to Work to Heal Spinal Cord Injury

Posted on by

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.

Reference:

[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.

Links:

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


Snapshots of Life: Healing Spinal Cord Injuries

Posted on by

Nerve cell on a nanofiber gel

Credit: Mark McClendon, Zaida Alvarez Pinto, Samuel I. Stupp, Northwestern University, Evanston, IL

When someone suffers a fully severed spinal cord, it’s considered highly unlikely the injury will heal on its own. That’s because the spinal cord’s neural tissue is notorious for its inability to bridge large gaps and reconnect in ways that restore vital functions. But the image above is a hopeful sight that one day that could change.

Here, a mouse neural stem cell  (blue and green) sits in a lab dish, atop a special gel containing a mat of synthetic nanofibers (purple). The cell is growing and sending out spindly appendages, called axons (green), in an attempt to re-establish connections with other nearby nerve cells.


Regenerative Medicine: New Clue from Fish about Healing Spinal Cord Injuries

Posted on by

Zebrafish Spinal Cord

Caption: Tissue section of zebrafish spinal cord regenerating after injury. Glial cells (red) cross the gap between the severed ends first. Neuronal cells (green) soon follow. Cell nuclei are stained blue and purple.
Credit: Mayssa Mokalled and Kenneth Poss, Duke University, Durham, NC

Certain organisms have remarkable abilities to achieve self-healing, and a fascinating example is the zebrafish (Danio rerio), a species of tropical freshwater fish that’s an increasingly popular model organism for biological research. When the fish’s spinal cord is severed, something remarkable happens that doesn’t occur in humans: supportive cells in the nervous system bridge the gap, allowing new nerve tissue to restore the spinal cord to full function within weeks.

Pretty incredible, but how does this occur? NIH-funded researchers have just found an important clue. They’ve discovered that the zebrafish’s damaged cells secrete a molecule known as connective tissue growth factor a (CTGFa) that is essential in regenerating its severed spinal cord. What’s particularly encouraging to those looking for ways to help the 12,000 Americans who suffer spinal cord injuries each year is that humans also produce a form of CTGF. In fact, the researchers found that applying human CTGF near the injured site even accelerated the regenerative process in zebrafish. While this growth factor by itself is unlikely to produce significant spinal cord regeneration in human patients, the findings do offer a promising lead for researchers pursuing the next generation of regenerative therapies.