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Snapshots of Life: Healing Spinal Cord Injuries

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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.

So, what spurred this particular neural stem cell to reactivate itself? The secret lies in the nanofiber gel. It’s been specially engineered to mimic the structure within a healthy spinal cord, as well as seeded with biochemical signals that naturally prompt the cell to grow and start forming connections.

The image—a winner in the Federation of American Societies for Experimental Biology’s 2016 BioArt competition—was taken by Mark McClendon and Zaida Alvarez Pinto, researchers in the lab of Samuel Stupp at Northwestern University, Evanston, IL. They used a scanning electron microscope to capture the image and then colorized the neural stem cell and nanofibers to make it a work of art.

McClendon and Alvarez Pinto hope that this gel, along with other bioengineered materials under development in the Stupp lab, might one day be used to prevent or reverse loss of function in people who suffer severe spinal cord or other nerve injuries. The science isn’t quite there yet. But the lab continues to build on the productive intersection of materials science, biology, and medicine to push closer to their end goal.

Already, they’ve shown that nanofibers, including growth-inducing peptides, can self-assemble after being injected into the injured spinal cords of mice. With those nanofibers in place, the researchers found that the animals’ damaged spinal cords were able to mend themselves back together [1]. Nine weeks after the injury, the treated animals were once again able to move their hind limbs. Importantly, the nanofiber gel also helped to prevent the formation of scar tissue, which would otherwise interfere with the healing process.

While human tests of the nerve-regenerating nanofiber gel is likely years away, the promise of regenerative medicine is clearly remarkable and may extend beyond the nervous system. In fact, these and other researchers are already pursuing similar strategies for regenerating heart, muscle, bone, and cartilage.

Reference:

[1] Self-assembling nanofibers inhibit glial scar formation and promote axon elongation after spinal cord injury. Tysseling-Mattiace VM, Sahni V, Niece KL, Birch D, Czeisler C, Fehlings MG, Stupp SI, Kessler JA. J Neurosci. 2008 Apr 2;28(14):3814-23.

Links:

Tissue Engineering and Regenerative Medicine (National Institute of Biomedical Imaging and Bioengineering/NIH)

Stupp Lab (Northwestern University, Evanston, IL)

BioArt (Federation of American Societies for Experimental Biology, Bethesda, MD)

NIH Support: National Institute of Biomedical Imaging and Bioengineering; National Institute of Neurological Disorders and Stroke