Optical images of polyethylene glycol scaffolds expanding in response to stretching.(Note: green tone added to image.) Image: UC San Diego / Shaochen Chen |
A new biomaterial designed for repairing damaged human
tissue doesn’t wrinkle up when it is stretched. The invention from
nanoengineers at the Univ. of California, San
Diego marks a breakthrough in tissue engineering
because it more closely mimics the properties of native human tissue.
Shaochen Chen, professor in the Department of
NanoEngineering at the UC San Diego Jacobs School of Engineering, hopes future
tissue patches, which are used to repair damaged heart walls, blood vessels and
skin, for example, will be more compatible with native human tissue than the
patches available today. His findings were published in Advanced Functional
Materials.
The new biomaterial was created using a new biofabrication
platform that Chen is developing under a four-year, $1.5 million grant from the
National Institutes of Health. This biofabrication technique uses light,
precisely controlled mirrors, and a computer projection system—shined on a
solution of new cells and polymers—to build three-dimensional scaffolds with
well-defined patterns of any shape for tissue engineering.
“We are also exploring other opportunities,” said Chen. “It’s a new material. I think it’s just a matter of time before more people
will pick up and find applications for it in defense, energy and
communications, for instance.”
Although Chen’s team is focused on creating biological
materials, he said the manufacturing technology could be used to engineer many
other kinds of materials including metal parts used in ships and spacecraft,
for example.
Shape turned out to be essential to the new material’s
mechanical property. While most engineered tissue is layered in scaffolds that
take the shape of circular or square holes, Chen’s team created two new shapes
called “reentrant honeycomb” and “cut missing rib.” Both shapes exhibit the
property of negative Poisson’s ratio (i.e. not wrinkling when stretched) and
maintain this property whether the tissue patch has one or multiple layers. One
layer is double the thickness of a human hair, and the number of layers used in
a tissue patch depends on the thickness of the native tissue that doctors are
trying to repair. A single layer would not be thick enough to repair a heart
wall or skin tissue, for example. The next phase of research will involve
working with the Department of Bioengineering at the Jacobs School of
Engineering to make tissue grafts to repair damaged blood vessels.