By Estel Grace Masangkay

Researchers from the University of Michigan have discovered how mechanical forces in the environment influence stem cell growth and differentiation. The scientists arrived at the findings using a key ingredient in Silly Putty for their experiments.

Using an ultrafine carpet made out of polydimethylsiloxane, a key ingredient in Silly Putty, the scientists were able to coax stem cells to morph into working spinal cord cells. The Silly Putty component was made into a specially engineered growth system with microscopic posts. By varying the post height, the researchers were able to adjust the stiffness of the surface where the cells are made to grow.

Jianping Fu, assistant professor of mechanical engineering at the University of Michigan, said, 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.

Stem cells that were grown on tall, softer micropost carpets morphed into nerve cells faster and more often than those grown on stiffer surfaces. The colonies of spinal cord cells that grew on softer micropost carpets were also 10 times larger and four times more pure than those grown on rigid carpets or traditional plates.

The study is the first to directly link physical signals to human embryonic stem cells differentiation, in contrast to chemical signals. Professor Jianping Fu says the findings may lead to a more efficient way of guiding stem cells to differentiate and provide specialized therapies for diseases such Alzheimers, Huntingtons, Lou Gerhrigs disease, and others. 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, said Professor Jianping.

The study from the University of Michigan was published online at Nature Materials this week.

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U-M Researchers Use Silly Putty Ingredient To Study Stem Cells

Working esophagi from stem cells could be used to aid cancer patients in the future

Jason Goldman / Flickr Creative Commons

Doctors have implanted bio-engineered tracheas in patients, and researchers have experimented with growing bladders and kidneys. Now, another organ joins that list: the esophagus, which brings food and water to the stomach.

An international team of scientists working at Kuban State Medical University in Krasnodar, Russia, has built a working esophagus from stem cells, and implanted the organ into rats, the researchers say. The new esophagus functioned just as well as the rats' natural organs, said the researchers, who detailed their work today (April 15) in the journal Nature Communications.

Every year, about 18,000 people in the United States are diagnosed with esophageal cancer, and others suffer from congenital defects, or are injured after medical procedures or swallowing caustic materials. Many of these cases require surgery, which can involve taking a section of the small intestine or the stomach to replace part of the esophagus.

Unfortunately, this isn't always the best solution. Patients can suffer complications, and many still have trouble swallowing solid food after surgery. [5 Crazy Technologies That Are Revolutionizing Biotech]

Researchers led by Paolo Macchiarini of the Karolinska Institutet in Stockholm took a section of a rat's esophagus and removed the cells, leaving behind a scaffold of protein. Such "decellularization" is now a common technique for making structures for cells to latch onto when doing regenerative organ experiments.

To test whether the scaffold would be strong enough to stand up to repeated cycles of expansion and contraction, the scientists pumped air into it 10,000 times, allowing it to blow up and shrink.

The researchers then took stem cells called allogeneic mesenchymal stromal cells, which don't cause an immune reaction when implanted into tissue. Scientists placed these cells on the scaffold, allowing the esophagus to grow for three weeks.

They then implanted the esophagus into a rat, replacing up to 20 percent of its esophagus with the engineered version. They repeated this procedure in nine more rats.

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Lab-Grown Esophagi Implanted in Rats