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 Implanting the pig material at the wound site
enticed the patient's own stem cells — master cells that can
transform into various kinds of cells in the body — to become muscle
cells and regenerate tissue that had been lost, the researchers
said.
The study was small, involving only five male patients, but its
results suggested that this procedure could offer new hope to a
category of patients, including troops who suffered major war
injuries, with scant good treatment options, they added.
All five patients, including two U.S. soldiers hurt by bombs planted
by insurgents, had badly damaged leg muscles. The research was
backed by $3 million in funding over five years from the U.S.
Defense Department, said Dr. Stephen Badylak of the University of
Pittsburgh, who led the study.
Thousands of American troops have been left with serious physical
impairments after sustaining wounds involving major loss of muscle
tissue in roadside bombings and other incidents since 2001 in the
wars in Iraq and Afghanistan.
When a large amount of muscle is lost in vehicle crashes, industrial
accidents, bomb blasts or other traumas, the body is unable to
replace it and the site forms scar tissue that lacks the
functionality of the lost muscle.
Existing treatments include surgery to remove scar tissue or replace
it with muscle from somewhere else in the body, but these methods do
not yield satisfying results and are hard on patients, the
researchers said.
"Nothing has ever worked. There's been multiple things tried: the
hype and the hope of stem cell therapy, new surgical techniques,"
Badylak said.
This study, published in the journal Science Translational Medicine,
demonstrated for the first time the regeneration of functional
muscle tissue in people with major muscle loss.
"While the number of patients was small, we were very encouraged by
the data. And we were seeing very dramatic improvements in quality
of life for some of our patients," added Dr. J. Peter Rubin of the
University of Pittsburgh School of Medicine, another of the
researchers.
The doctors implanted material from a pig's urinary bladder called "extracellular
matrix" — the non-cellular component including collagen present
within all tissues and organs — to serve as scaffolding for the
rebuilding of lost muscle mass.
This material acted as a "homing device" to recruit existing stem
cells in the body to rebuild healthy muscle tissue at the site of
the injury, the researchers said.
Pig parts have been used for years in surgical procedures. Pig
bladder "extracellular matrix" has been used in hernia repair and
fixing chest wall defects after cancer removal.
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Before trying the procedure in people, the researchers said they
successfully tested it in mice with muscle injuries.
WARTIME INJURIES
To take part in the study, the five men had to have lost at least 25
percent of leg muscle volume and function at least six months
earlier and then completed physical therapy for three to six months
until their function and strength no longer improved.
The doctors then implanted the pig material and directed the men to
resume physical therapy for up to six more months. Biopsies and
scans confirmed that muscle growth had taken place.
The patients hurt by bomb blasts were a 27-year-old who lost 83
percent of his thigh muscle and had undergone 50 previous surgical
operations, and a 28-year-old who lost 68 percent of his thigh
muscle and had 14 previous operations.
The other three men had calf injuries, including one who also
came from the military but was hurt while exercising and not in
combat, and two civilians with severe skiing injuries.
"Frankly, most of these patients have been through hell. These are
serious injuries," Badylak said. "In fact, one or two of the
patients even considered amputation at one point because they've
just been through so much."
Three of them, including both soldiers hurt by bombs, were measured
six months after the implantation operation as stronger in five
categories by at least 20 percent — and often by far more than that.
The other two men also showed broad improvement but not in all five
measures, the researchers said.
Badylak said four additional patients, including one woman, have
since undergone the procedure with good results.
(Reporting by Will Dunham; editing by Phil Berlowitz)
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