Stem cell research uses Silly Putty
A key element of the popular children's toy Silly Putty could help scientists develop stem cell treatments for nerve and brain disorders such as motor neurone disease and Alzheimer's, a study suggests.
Researchers used the molecule that gives Silly Putty its unusual properties to grow working spinal cord cells on a soft, ultra-fine carpet.
They found that motor nerves grew faster and more often on the material than they did on a normal rigid surface.
The neurones also showed electrical activity comparable with that of motor nerves in the body.
The study is the first to show that physical, as well as chemical, signals directly affect the development of human embryonic stem cells.
Silly Putty, created by accident during Second World War research into potential rubber substitutes, bounces but also flows like a liquid and breaks when hit sharply.
A silicone polymer molecule called polydimethylsiloxane (PDMS) is mainly responsible for the odd properties that have made Silly Putty a hit with children around the world.
The new research involved coaxing embryonic stem cells to grow and develop on a soft "carpet" made from PDMS threads.
After 23 days, colonies of spinal cord motor neurones appeared that were four times purer and 10 times larger than those grown on traditional plates.
Lead scientist Dr Jianping Fu, from the University of Michigan in Ann Arbor, said: "This is extremely exciting. To realise 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 micro-engineered surfaces to control mechanical environmental signals."
The researchers, who describe their work in the journal Nature Materials, believe the technique could lead to better ways of guiding the "differentiation" of stem cells.
Differentiation is the process by which a "blank slate" stem cell morphs into one of the body's more than 200 different cell types.
Dr Fu specialises in amyotrophic laeral sclerosis (ALS), also known as motor neurone disease. The illness, suffered by UK physicist Professor Stephen Hawking, causes paralysis by destroying motor cells in the brain and spinal cord.
The hope is that stem cell therapies might in future enable patients with motor neurone disease and other conditions affecting the brain and movement to grow new nerves.
Professor Eva Feldman, from the University of Michigan's medical school, who is collaborating with Dr Fu, said: "For ALS, discoveries like this provide tools for modelling disease in the laboratory and for developing cell-replacement therapies."
Dr Fu added: "Our work suggests that physical signals in the cell environment are important in neural patterning, a process where nerve cells become specialised for their specific functions based on their physical location in the body."