It seems unlikely that Silly Putty - a children's moulding toy - could prove useful in the medical world. But new research from the University of Michigan suggests that a key ingredient used in Silly Putty can turn embryonic stem cells into working spinal cord cells more efficiently.

The research team, including Jianping Fu, professor of mechanical engineering at the University of Michigan (U-M), says their findings may lead to new treatments for neurological disorders, such as amyotrophic lateral sclerosis (Lou Gehrig's disease), Huntington's disease or Alzheimer's disease.

Stem cells have the potential to develop into more than 200 different types of cells in the body. Because of their versatility, researchers are increasingly investigating the use of stem cells for the treatment of numerous medical conditions.

Medical News Today recently reported on the creation of a "mini-heart" using patients' own stem cells, which could help improve treatment for people who have impaired blood flow. In a more recent study, researchers created the first stem cell model for bipolar disorder that could lead to new treatments for the condition.

But as in all medical research, scientists are always looking for ways to improve on existing techniques. The U-M team wanted to see if they could improve the way stem cells are changed into other cell types - a process known as "differentiation."

'Plush-like' surfaces boost stem cell growth

The team assessed whether an ingredient called polydimethylsiloxane - a silicone that gives Silly Putty its unusual stretchy ability - could boost the efficiency of embryonic stem cell differentiation.

Using this component, the investigators developed "ultrafine carpets." They describe these as adjustable surfaces on which stem cells can grow. They were able to adjust the "post" height and stiffness of growth surfaces. They say that shorter posts are more rigid in texture, similar to an industrial carpet, while taller posts are softer, like a plush carpet.

When the researchers grew embryonic stem cells on plush-like surfaces, they found that the cells turned into nerve cells much quicker and more often than stems cells that grew on industrial-like surfaces.

The team also found that colonies of spinal cord cells - neurons responsible for muscle movement - that grew on plush-like surfaces were 10 times larger and four times purer than those grown on industrial-like surfaces or traditional plates.

Commenting on the findings, Prof. Fu says:

"This is extremely exciting. To realize promising clinical applications of human embryonic stem cells, we need a better culture system that can reliably produce more target cells that function well. Our approach is a big step in that direction, by using synthetic microengineered surfaces to control mechanical environmental signals."

Potential for developing cell-replacement therapies

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Researchers used an ingredient found in Silly Putty to create "ultrafine carpets" on which to grow working motor neurons from embryonic stem cells.
Image credit: Ye Tao, Rose Anderson, Yubing Sun, Jianping Fu.

In addition to these findings, the researchers discovered that the spinal cord cells grown on plush-like surfaces demonstrated electrical behaviors similar to that of neurons found in the human body.

Furthermore, the team identified a signaling pathway called Hippo/YAP, which regulates these electrical behaviors. Hippo/YAP also plays a part in organ size control and tumor growth prevention.

"Our work suggests that physical signals in the cell environment are important in neural patterning, a process where nerve cells become specialized for their specific functions based on their physical location in the body," says Prof. Fu.

The researchers say their study, recently published in the journal Nature Materials, is the first to directly link physical signals to human embryonic stem cell differentiation, rather than chemical signals.

In collaboration with doctors at the U-M Medical School, Prof. Fu and colleagues are now using this novel stem cell growth technique to develop new treatments for patients with Lou Gehrig's disease - a condition that kills motor neurons in the brain and spinal cord, leading to paralysis.

"Professor Fu and colleagues have developed an innovative method of generating high-yield and high-purity motor neurons from stem cells," says Prof. Eva Feldman of the U-M Medical School. "For ALS (Lou Gehrig's disease), discoveries like this provide tools for modeling disease in the laboratory and for developing cell-replacement therapies."

Medical News Today recently reported on a study detailing how stem cells can be cultivated without using human or animal cells.