“Motor neurons are particularly vulnerable cells,” says Tom Jessell.

“But even in the midst of ALS, certain types of motor neurons found at one end of the spinal cord,” he continues, “tend to resist the disease—oculomotor neurons, for example. Why is that?

“If we knew, perhaps we could make the rest of the spinal cord equally resistant.
“The problem is the body holds 150 different subtypes of motor neuron. And every type is molecularly and genetically distinct. Very little is known about the differences.

“What’s made them different? It’s the various signaling programs turned on in the developing spinal cord—and sometimes later.”

The new iPS (stem) cell technology should give Jessell and colleagues an extremely valuable new tool to understand the programs and what they do.

“Presently, we’re converting mouse stem cells into motor neuron subtypes. We’re identifying different transcription factors and genes that convert stem cells into the subtypes of motor neurons.

“Can you make, for example, neurons that move the gracilis muscle? That should be possible. You should be able to get every type of motor neuron from programming stem cells.

Then we could make oculomotor neurons and see how they differ from others in the spinal cord.

“The iPS work will let us use the basic developmental information we have about motor neurons as a bridge to understand precisely how they function. And that, we would hope, will give us new therapies.”

Learn more about Tom Jessell