Silly Putty May Help Treat Neurological Disorders

Could a key ingredient in a children’s toy play a role in better treating neurological disorders such as Lou Gehrig’s, Huntington’s, and Alzheimer’s disease?

New research suggests that it just might, as investigators from the University of Michigan were able to turn human embryonic stem cells into working spinal cord cells more efficiently by growing the cells on a soft, ultrafine carpet made of a critical component of Silly Putty.
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Jianping Fu, PhD, assistant professor of mechanical engineering at the University of Michigan Medical School, and colleagues designed a specially engineered growth system in which microscopic posts of the Silly Putty component polydimethylsiloxane served as the threads. The researchers varied the post height, adjusting the stiffness of the surface they grow cells on. According to the authors, shorter posts are more rigid, comparable to an industrial carpet, while taller posts are softer and more plush.

The team found that stem cells growing on the tall, softer micropost “carpets” turned into nerve cells much faster and more frequently than those growing on the stiffer surfaces. After 23 days, the colonies of spinal cord cells that grew on the softer micropost carpets were 4 times more pure, and 10 times larger than those growing on either traditional plates or rigid carpets.

The study “has applied a novel ultrafine cell culture substrate made of microscopic posts of a key ingredient in Silly Putty for human embryonic stem cell culture,” explains Fu. “And we have found that such substrates can efficiently drive human embryonic stem cells into functional motor neurons.”

The study demonstrates that the new motor neurons obtained on soft micropost carpets showed electrical behaviors similar to those of neurons in the human body, according to the researchers. The researchers also identified a signaling pathway involved in regulating the mechanically sensitive behaviors. The pathway the investigators focused on—known as Hippo/YAP—is also involved in controlling organ size, and both causing and preventing tumor growth.

“So far, no pharmaceutical drug is available to completely halt the progression of neurological diseases like Lou Gehrig’s or Alzheimer’s disease,” says Fu, adding that an emerging approach currently under rigorous clinical testing is to provide patients with functional neuron cells generated from stem cells.

“Our study suggests an exciting approach for large-scale production of human embryonic cells,” says Fu, “and their functional derivatives for treating neurological disorders.”

—Mark McGraw

Reference

Sun Y, Yong K, et al. Hippo/YAP-mediated rigidity-dependent motor neuron differentiation of human pluripotent stem cells. Nature Materials. 2014.