ERJ staff report (TP)
Michigan – ‘Silly Putty’, a flexible and fun American toy based on silicone polymers, has often been hailed capable of fixing the world’s problems. Now, a team of mechanical engineers from the University of Michigan have proven it, reported Liat Clark for Wired.
Taking polydimethylsiloxane, a type of silicone used in breast implants and the key ingredient that gives ‘Silly Putty’ its viscoelastic properties, the team built a growth system to help human embryonic stem cells develop into motor neuron cells. Studies have been carried out in the past to demonstrate that different chemical properties are required to help coax the pluripotent cells into different types of adult cells. This study focused on the physical – the scaffolding upon which that maturation process takes place.
The scaffolding was made up of these polydimethylsiloxane threads – the tiny ‘Silly Putty’ threads are referred to as "microposts" in a paper describing the technique, and an array of these makes up the membrane for the cells to thrive on. The flexible quality of the material meant that when the team produced longer threads, the membrane became softer. This allowed the cells to develop far faster than if rigid, short ones were used.
Within 23 days, motor neurons being grown were ten times bigger than those matured in the lab using the usual methods or on the stiff membranes. Moreover, the cells that were produced exhibited many of the traits of their mature counterparts, including electrical properties and chemical signalling pathways. The paper published in Nature is actually named after that signalling pathway, Hippo/YAP, which is key to controlling organ size through the regulation of cell production and dispersion.
The hope is the method can speed up research into debilitating diseases, such as amyotrophic lateral sclerosis (ALS) where these key cells are lost.
"For ALS, discoveries like this provide tools for modelling disease in the laboratory and for developing cell-replacement therapies," said Eva Feldman, a professor of Neurology at the University of Michigan's School of Medicine not involved in the study.
Feldman is already picking up from the team's lead, using the approach to attempt to engineer motor neuron cells from patient's own cells.
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Full story from Wired