Oh, grow a spine

Spinal cord injuries are no joke (how did we get from the Featured Image to this!? I’ll get there)

Some of us have been lucky enough that all we get is temporary paralysis – I remember in 3rd grade, some jerk trying to be funny (and to impress a girl) swept my arms out from under me mid-cartwheel instead of holding me by the waist to help complete the cartwheel. Landed on my head, got the wind knocked out of me, couldn’t feel my legs for like 10 minutes (but I could see them trembling horribly), and so on. That was a scary time, but it did make him the most hated guy in all of 3rd grade, didn’t help that he was laughing when I was on the floor probably dying. Even the girl he was crushing on was the first to rush over to me and tell him off. She even held my hand. Ten points for Jonny, tee-hee-hee.

Sadly (apologies for the change in tone), some get their spinal cords terribly injured or even severed, which means that depending on where it happens, everything below will be permanently paralyzed. It happened to the late Christopher Reeve, and it still doesn’t sit well with me that, according to comedian Chris Rock, “Superman can’t walk!”

Stem cells are still a touchy ethics issue for regrowing spinal cells, but there may be a work-around (if one doesn’t mind a few dead mice for testing): a team of researchers from Italy and Spain recently published a paper in Science Advances that proposes using carbon nanotubes to help reconnect spinal tissue. Before we go on, just what are carbon nanotubes? In short, just about one of the coolest things ever made in a lab: they are sheets of carbon, often only a few atoms thick (so we’re talking super small-scale here, people), rolled into tubes. They’re good conductors of heat and electricity, not to mention incredibly tough. Ever seen carbon fiber? Similar idea, only smaller. The things you can do with a pencil, of all things.

contub_v1_0_08_2
(source: Wikimedia Commons, CC-BY-SA-30, user: Gmdm)

Why do this? When spinal injuries occur, there might be tears in the spinal tissues. Sure, they can grow back, but would they grow back properly? Usmani et al.‘s study uses carbon nanotubes to help guide spinal tissue back together, kind of like the trellises people use for grapevines in wineries. Told you I’d get to explaining the Featured Image. Boosh.

With the kind of strides we’re making in 3D printing, making these extremely tiny ‘nervous trellises’ is going to be a lot easier than making using just chemicals – one can get the shape that you want, likely to be a mesh of tubes rather than pipes.  Anyway, these meshes of tubes were cultured with spinal tissue taken from mice (hey, I warned you about the mice). These pieces of spinal cord were separated ~1.5 to 2 mm apart, which is quite a long distance for spinal tissue. Without all the procedural details (you may read up on it if you’re so inclined), there were two samples, one without the carbon mesh (‘control’), and one with the mesh.

So what happened? 2 weeks later, they saw some nerve growth. In the control sample, the nerves grew into aligned nerve fibers, but the meshed-up sample ended up making a 3-dimensional web of nerves. They were pretty much grown along the mesh, which you would expect. But let’s get to the important bit – how does it fire? After all, these are spinal tissues, they should be firing signals between brain and muscles. Both of them are firing electrical signals (so that’s good), and the control sample demonstrated some reconnection between the spinal cord slices. Turns out that the meshed-up sample demonstrated an almost complete reconnection between the spinal cord slices. It simply healed better.

Although more testing showed that it the carbon mesh doesn’t trigger an immune response, the authors did give a little caveat (a little Latin you can drop on your peers): there are other physical, chemical, and biological factors that could affect how spinal tissue regrow and regain function that they weren’t able to test (there really are so many, and scientific research often is about controlling the number of variables). But hey, this is still good progress for spinal cord research. Just a little bit of know-how, a 3D printer, and some pencil ‘lead’, and you really could grow a spine to heal an injury, maybe even improve it.

You might still need a bit of courage to grow your spine (that’s the wordplay, yo) – about half of you reading this probably felt a slight twinge in your back whenever I said “spinal cord slices.”

Featured article: Usmani S, Aurand ER, Medelin M, Fabbro A, Scaini D, Laishram J, Rosselli FB, Ansuini A, Zoccolan D, Scarselli M, De Crescenzi M, Bosi S, Prato M, Ballerini L. (2016) 3D meshes of carbon nanotubes guide functional reconnection of segregated spinal explants. Scie. Adv. 10.1126/sciadv.1600087

Featured image credit: Public domain (United States Dept. of Agriculture, Natural Resources Conservation Service)

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