TREATING DEADLY GUT DISEASE IN PREMATURE BABIES
Premature babies face
a host of medical challenges at birth, but none as deadly and mysterious as a
disease called necrotizing enterocolitis (NEC). The condition creates an
inexplicable combination of inflammation and infection that causes parts of the
intestine to die. NEC progresses at a ruthless speed, leaving physicians with
few options -- typically supportive care, emergency surgery or antibiotics.
Only half of newborns who undergo surgery survive, and they often face serious
life-long complications.
"In the fifty
years since necrotizing enterocolitis was first identified, we've accomplished
relatively little to change its devastating course. Even worse, we don't know
which babies will get it. One minute, a child can appear healthy, but then be dead
from NEC hours later," said Gail Besner, MD, chief of pediatric surgery at
Nationwide Children's Hospital.
That may be about to
change thanks to two major breakthroughs driven by Besner and Surgeon-in-Chief
at Nationwide Children's R. Lawrence Moss, MD.
After nearly two
decades of work, their separate efforts have yielded both the discovery of a
biomarker that can help predict which babies will get the disease, as well as
treatments that can restore the intestine's natural ability to protect itself
against NEC.
"These
researchers' advances offer innovative approaches to necrotizing enterocolitis
that may someday make it a more predictable and better managed complication of
prematurity," said John Barnard, MD, President of the Nationwide
Children's Research Institute and Pediatric Director of The Ohio State
University Center for Clinical and Translational Science (CCTS).
Growth factors, stem
cells offer gut protection
For Besner, the key
has always been to prevent NEC before it can start. In the 1990's, she began
looking closely at what was happening at the molecular level to an immature
bowel in the throes NEC. Besner made a major discovery, observing that a
protein called heparin-binding EGF-like growth factor (HB-EGF) -- which she
initially discovered -- played a life and death role in protecting premature
infants from NEC.
In numerous studies,
Besner showed that without HB-EGF, the structures within the intestines that
maintain barrier function and integrity, including a massive network of nerves
and blood vessels, became easily injured and beyond repair. The addition of
HB-EGF had the opposite effect, helping protect intestines from injury in
animal models of NEC.
From that molecular
level understanding of NEC, Besner developed a bigger picture hypothesis about
how the nerve damage within an immature gut impacted the disease's development
and progression -- and where a solution might be found.
"It is
fascinating that we have more nerves in our gut than in our brain, and the
'heart' of our immune system is actually in our intestines," said Besner,
who also is a professor of pediatrics and surgery at Ohio State's College of
Medicine and holds their H. William Clatworthy Jr. Professorship in Surgery.
"We found that NEC seriously disrupts the gut's nervous system both short
and long term. In fact, the immature nervous system of the premature infant's
intestine may actually predispose the baby to developing NEC in the first
place. That revelation opened to door to consider stem cell therapy to restore
nerves needed for the gut and possibly other organ systems dysregulated by NEC
to function properly."
The work, published
in Stem Cell Research and Therapy, earned
her the 2013 BioMed Central Research Award in Translational Medicine. It also
provided the foundation for a series of studies showing that intravenous or
even intraperitoneal administration of neural stem cells or mesenchymal stem
cells could heal tissue damage in animal models of NEC. Besner also found that
the healing effect was magnified when HB-EGF was administered at the same time
as stem cells, or when stem cells were genetically manipulated to overexpress
HB-EGF.
"The different
types of stem cells effectively migrated to where the intestines were injured,
preventing further damage and inflammation, and helped heal the wound. The
transplantation of neural stem cells also appears to repair neural
functionality of the gut in ways that could help prevent long term digestive
issues that are so common among babies who survive NEC," said Besner.
While the results
are encouraging, Besner notes that no treatment will be truly useful until
doctors can actually identify which babies are at the highest risk for
developing NEC. And that's where she says Moss's research is the perfect
complement to her discoveries.
"The idea that
we could prevent NEC with stem cells is exciting, but we can't give that
therapy -- or any therapy for that matter -- to every premature baby,"
said Besner. "Moss' research is the critical key to making prevention and
treatment practical and possible."
"We were asking
the wrong questions"
Prevention of NEC
wasn't initially top of mind for Moss. Instead, the clinician-scientist began
researching a question that had plagued surgeons for years: of the two types of
surgical procedures commonly used to treat NEC, which one had the better
outcomes? To find the answer, Moss' team initiated a randomized clinical trial.
This approach was the first of its kind to answer questions regarding surgical
therapy for infants with a life threatening problem. The results of this study
shocked the surgical community.
"It turned out
that both procedures had the same survival rate. And that rate wasn't where we
wanted it to be anyway," recalled Moss, who is also the E. Thomas Boles,
Jr. Professor of Surgery at Ohio State's College of Medicine. "That's when
I realized we were asking the wrong question. We needed to intervene before
these babies required surgery. The only effective way to do that was to predict
which babies were going to get NEC in the first place."
As a first step,
Moss began exploring risk factors associated with the prevention and
development of NEC, conducting some of the largest multicenter prospective NEC
studies ever done. Teaming up with five other university-based pediatric
teaching hospitals, including Yale, Stanford and Johns Hopkins, Moss helped
create an algorithm for clinicians to use which would identify those children
at greatest risk for getting and dying from NEC. The algorithm was based on a
combination of laboratory and clinical findings -- but Moss and his colleagues
realized this algorithm was not able to predict which babies were at greatest
risk of NEC with sufficient accuracy.
This led the
researchers to investigate the technique of combining biologic date from each
individual patient with the clinical algorithm. They started by analyzing tens
of thousands of proteins in the urine of children who had suspected NEC or
sepsis -- a type of systemic infection. The group identified seven proteins
that could potentially indicate the presence and severity of NEC. Most
recently, the group combined the use of these biomarkers with the algorithm and
determined the combination was able to predict prognosis of children with NEC
with up to 90% accuracy.
"There is
definitely more work we need to do to refine the way we could use the
biomarker, the algorithm or the combination of the two," said Moss.
"But after so many years of not being able to reassure parents, of not
having real solid evidence to base my clinical choices on -- I feel like we're
headed in the right direction."
Pushing the
boundaries of NEC knowledge
Both investigators
acknowledge that despite the intense need, the challenges of getting a new
therapeutic or diagnostic test to children are substantial. Regulatory and
economic factors surrounding pediatric drug approvals make many manufacturers
hesitant to invest the resources needed to bring a new drug or device to
market.
Moss says that's
where support, like the kind provided by the CCTS, has been critical to helping
researchers build a solid foundation of science showing that large scale
clinical trials based on their work would likely yield effective therapeutics.
"Federal
funding and support from the CCTS has enabled us to create an environment that
lets ideas flourish and allows us to help patients while keeping in touch with
the bench science that can change those patients' lives," says Moss.
"Without that, we would not be in this place today where we have a
realistic hope that we will soon be able to say -- we know how to identify
which babies are going to get NEC, and we think we know how to stop it before
it ever starts."
Both scientists hope
that clinical trials using the biomarker and/or stem cell therapies will
initiate within the next five to eight years. In the meantime, both
investigators continue to redefine the boundaries of current NEC knowledge.
Moss is leading a multi-institutional study to validate biomarkers that can
detect the onset of a deadly systemic infection in children with NEC. Besner is
exploring the long term effects of NEC on overall neurodevelopment. She is also
working with regenerative medicine experts at Nationwide Children's and The
Ohio State University to develop tissue scaffolds that use a child's own cells
to regrow and replace sections of damaged or diseased bowel.
"I am hopeful
that I will not go through yet another decade of telling parents that I don't
know if their child will survive surgery," says Besner. "Instead, I
am looking forward to telling those parents -- 'It looks like your baby is at risk
for developing NEC. We have something that can protect him, and he's going to
be OK."
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