By combining living cells with a synthetic substrate, researchers have found that a rubberlike, elastic film coated with a single layer of cardiac muscle cells can engage in lifelike gripping, pumping, walking, and swimming when stimulated with an electric shock.
The exact movement undertaken by the hybrid muscular thin films (MTFs) can be adapted by controlling muscle alignment relative to the shape of the flexible film - some even contract spontaneously without user intervention.
Researchers Kevin Kit Parker and Adam W Feinberg at Harvard University, USA engineered the adhesion and alignment of rat heart muscle cells onto thin films of a polymer called polydimethylsiloxane. The key to the MTFs' high contractile forces was the alignment of all the muscle cells in a single direction, allowing the billions of molecular motors inside the cells, organized into structures called sarcomeres, to simultaneously fire and produce one big contraction.
The thin films can be cut into any shape. The type of action performed depends on the shape of the MTF and the orientation of the sarcomeres. With rectangular MTFs and sarcomeres arrayed lengthwise, they roll up into tubes upon muscular contraction, resulting in a pumping action. A narrower, stiffer rectangular film contracts into a pinching motion, while a triangular MTF creates a kind of walking action.
The researchers say that these films could be made of other types of cells. Myocardial MTFs may one day be useful to repair organs, and thin films made with skin cells could be made into wound dressings that heal the same as skin cells.
"It's often difficult for researchers to scale up studies from the level of single cells to the level of tissues," Parker says. "Scientists could plate a polymer film with airway smooth muscle cells to simulate an asthma attack, with uterine cells to mimic the contractions of childbirth, or with cells from the gastrointestinal system to test new drugs for acid reflux or irritable bowel syndrome."
There has been little success by scientists over the years to actually replicate natural muscle strength, rapid firing, or spatial capabilities. The bioengineers at Harvard University, who specialize in how cardiac muscle develops and how the heart's function follows from its form, have perfected the engineering of two-dimensional structures requiring precise sarcomere placement, but such precision has proved elusive in attempts to build three-dimensional structures.
This new approach sidesteps that limitation, they say. The three-dimensional shape is achieved by the spontaneous folding of a two-dimensional sheet.
Reference Harvard University
Source of top image Harvard University
For more attend Printed Electronics Europe 2008.