Intact spinal cord grown

[dragon]

And the advances keep on going.

Researchers from the University of Dresden have used embryonic stem cells to grow an intact spinal cord in a petri dish, the team reported this week. It’s an enormous achievement in a field that has long viewed neural tissue as the ultimate challenge, and one which could give hope to millions of people suffering from spinal cord injuries.

Neurons, the cells that form the thinking matrix of your brain and carry its orders to the rest of your body, are very difficult to grow. For a long time growing neurons was thought to be impossible, but then it was discovered that olfactory neurons regrow. This is why you can lose your sense of smell for a few days then slowly regain it; the neuron ends, basically open-ended synapses facing into your nasal cavity, are burned away by corrosive smells, but slowly grow back. Intense study followed this discovery, as scientists tried to track down how our olfactory neurons regrow, and others packed them directly into severed spinal cords with real success. In the image above, olfactory neurons have granted a lab rat regains some ability to walk again after being paralyzed (though to be fair, those same researchers are the ones who paralyzed it).
Even if you can grow one, the spinal cord still needs to form connections with an incredible number of body parts.

Even if you can grow one, the spinal cord still needs to form connections with an incredible number of body parts.

Now, rather than trying to force our spinal neurons to act like nasal ones, this German team may have a way of making new ones from scratch. Certain diseases and massive injuries could easily render a spine beyond all hope of repair, but in such a situation a full replacement might still work. Remember, though, that one of the reasons neurons are hard to work with is that they must form complex synaptic connections with other neurons to work properly; just growing the spinal cord is only half the battle, and the patient’s body still has to accept the new routing hardware and integrate it properly. Still, even just the ability to closely observe the growth of a full spinal cord could move neuronal research forward by leaps and bounds.

This technique worked essentially by letting the stem cells go to work and getting as far out of the way as possible; rather than introducing some novel new growth factor, the researchers basically just created an environment where the spine could grow just like it would in a body. Their setup involved inserting small bubbles of stem cells into a nutrient-rich growth medium and letting them go from there. Given all the opportunities they required, the cells naturally started coordinating and shunting growth factors around — most notably the trio of “hedgehog” signaling molecules.
The team's diagram shows inserted ESC colonies growing into larger cysts which eventually associate.

The team’s diagram shows inserted ESC colonies growing into larger cysts which eventually associate.

The most famous of the three-member band, both for its name and its function, is Sonic Hedgehog, which can stimulate directed neuron growth through its concentration gradient. A high concentration of Sonic Hedgehog leads the cord to grow motor neurons to carry the brain’s muscular commands, while a lower concentration near the top of the cord will lead to interneurons that wire up the spine itself. This is roughly analogous to growth factors in trees, where the “widen the trunk” molecule is made at the bottom and ferried up, and the “split the trunk into branches” molecule is made at the top and ferried down; the two opposing concentration gradients lead to the tree-shaped trees we all know so well, with branches becoming less common toward the bottom, where trunk-width takes priority.

In this case, the stem cells and spinal cord were from a mouse, which allowed for lower cost and ethical considerations, but the principles of growth and signaling should be the same. This technique made use of embryonic stem cells (ESCs), which in humans must be collected from fertility clinics and similar, but the ultimate human progenitor cell might not be necessary to further research. As scientists come to understand the mechanics of this breakthrough better, and replicate its results a few more times, it would presumably become possible to begin this process with induced stem cells made from adult tissue. If not, this will remain an interesting research tool with little real-world applicability due to the costs and regulatory problems with ESCs.
Star Trek had a spinal transplant episode -- but even in the 24th century, it's an experimental procedure.

Star Trek had a spinal transplant episode — but even in the 24th century, it’s an experimental procedure.

Lab-grown organs are coming far, fast. Somewhere in the world today there are gel baths and petri dishes growing human bladders, eyes, and penises, esophagi, livers, and breasts. Even the quest for lab grown meat falls under the same basic research umbrella, as scientists use similar techniques to create high quality chicken and bovine skeletal muscle. As with this spinal cord, each of these areas of research is trying to create laboratory conditions that perfectly mimic the body, so cells grow and develop normally.

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[Borgholio]

So now if someone tells you to grow a spine...you CAN!

[Guardsman Bass]

It's going to be an incredibly great day when they successfully test this in human subjects (allowing for repairs of major spinal injuries), or when they successfully create any number of other viable internal organs or limbs (kidneys especially - be able to print implantable kidneys would solve a ton of human suffering).