A Silly Putty Ingredient Helps Stem Cells Grow; Could Help Cure Alzheimer's, Lou Gehrig's Disease
If you thought silly putty was just another toy for your 5-year-old, then you will be amazed to know that the chief ingredient used to make it can also be used to help human embryonic stem cells, which have the potential to cure genetic diseases, grow. A new study conducted by researchers at the University of Michigan shows how the environment on the surface of this ingredient influences how the stem cells grow and what they grow into.
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Stem cells develop into many different cell types and body parts during early life and growth. In labs, scientists have seen them differentiate many times before through chemical processes, but this is the first time that they've used a physical environment to induce differentiation. During this process, stem cells develop into the more than 200 specialized cells that grow into muscle, bone, nerves, and organs.
For their research, the scientists grew stem cells on a soft, extremely fine carpet made of polydimethylsiloxane, the ingredient used in Silly Putty. The specially-engineered growth system comprised of "carpets" made of the ingredient. Microscopic posts of the ingredient served as threads, and varied in post heights, therefore varying the stiffness of the surface that the stem cells would grow on. While shorter posts provided more rigid surfaces, taller ones were softer.
The researchers grew the stem cells on the soft surfaces and saw that they turned into spinal cord cells - motor neurons that control the movement of muscles. The spinal cord cells grew faster than when they were on rigid surfaces, and in just 23 days they were four times more pure and 10 times larger than if they were grown on a rigid carpet or through traditional methods.
The findings show promise in stem cell therapies, and curing life-threatening diseases like amyotrophic lateral sclerosis (ALS, or Lou Gehrig's disease), Huntington's disease, and Alzheimer's disease. "This is extremely exciting," said Jianping Fu, an assistant professor of mechanical engineering at the university, in a press release. "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."
Fu's research is also being used by doctors at the university's medical school. Eva Feldman, a professor of neurology, studies ALS, a debilitating disease that paralyzes patients as it kills motor neurons in the brain and spinal cord. She believes that the damaged nerve cells can be regrown from both embryonic and adult varieties of stem cells. Using Fu's technique, she's attempting to grow fresh neurons from patients' own cells. Although, human testing has not yet been done, the doctors hope to begin soon.
"Professor Fu and colleagues have developed an innovative method of generating high-yield and high-purity motor neurons from stem cells," Feldman said in the release. "For ALS, discoveries like this provide tools for modeling disease in the laboratory and for developing cell-replacement therapies."
But Fu's research is not just about increasing cell count. The researchers analyzed the motor neurons they grew on the soft carpets and found that they generated electrical impulses similar to neurons in the human body. They also identified a signaling pathway involved in regulating mechanically sensitive behaviors. The pathway they found, which allows information to travel from the neuron's border to deep within, was called Hippo/YAP, and is involved with controlling organ size and both causing and preventing tumor growth.
Fu is confident that his research will show how embryonic stem cells turn into more specialized cells within the body. "Our work suggests that physical signals in the cell environment are important in neural patterning," he said in the release, "a process where nerve cells become specialized for their specific functions based on their physical location in the body."
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