HIGH DENSITY SOUND WAVES MAY AID REGENERATIVE MEDICINE
Researchers at the
University of Washington have developed a way to use sound to create cellular
scaffolding for tissue engineering, a unique approach that could help overcome
one of regenerative medicine's significant obstacles. The researchers will
present their technique at the 168th meeting of the Acoustical Society of
America (ASA), held October 27-31, 2014, at the Indianapolis Marriott Downtown
Hotel.
The development of the
new technique started with somewhat of a serendipitous discovery. The
University of Washington team had been studying boiling histotripsy -- a
technique that uses millisecond-long bursts of high-intensity ultrasound waves
to break apart tissue -- as a method to eliminate cancerous tumors by
liquefying them with ultrasound waves. After the sound waves destroy the
tumors, the body should eliminate them as cellular waste. When the researchers
examined these 'decellularized' tissues, however, they were surprised by what
the boiling left intact.
"In some of our
experiments, we discovered that some of the stromal tissue and vasculature was
being left behind," said Yak-Nam Wang, a senior engineer at the University
of Washington's Applied Physics Laboratory. "So we had the idea about
using this to decellularize tissues for tissue engineering and regenerative
medicine."
The structure that
remains after decellularizing tissues is known as the extracellular matrix, a
fibrous network that provides a scaffold for cells to grow upon. Most other
methods for decellularizing tissues and organs involve chemical and enzymatic
treatments that can cause damage to the tissues and fibers and takes multiple
days. Histrostipsy, on the other hand, offers the possibility of fast
decellularization of tissue with minimal damage to the matrix.
"In tissue
engineering, one of the holy grails is to develop biomimetic structures so that
you can replace tissues with native tissue," Wang said. Stripping away
cells from already developed tissue could provide a good candidate for these
structures, since the extracellular matrix already acts as the cellular
framework for tissue systems, Wang said.
Due to its bare
composition, the matrix also induces only a relatively weak immune response
from the host. The matrix could then theoretically be fed with stem cells or
cells from the same person to effectively re-grow an organ.
"The other
thought is that maybe you could just implant the extracellular matrix and then
the body itself would self-seed the tissues, if it's just a small patch of
tissue that you're replacing," Wang said. "You won't have any immune
issues, and because you have this biomimetic scaffold that's closer to the
native tissue, healing would be better, and the body would recognize it as
normal tissue."
Wang is currently
investigating decellularization of kidney and liver tissue from large animals.
Future work involves increasing the size of the decellularized tissues and
assessing their in-vivo regenerative efficacy.
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