July 17, 2007
"It may indeed be
possible to mend a
broken heart. Heart
attack patients who
have had to live
with the effects of
permanent cardiac
damage may be
encouraged by
research released
this month.
Scientists have
developed a
patch that may help
regrow damaged heart
muscle tissue and
may even reduce the
need for heart
transplants.
Success with the
patch in rats may
lead the way to new
methods of repairing
damaged human hearts
and possibly spare
some patients the
need for a heart
transplant,
according to
researchers
reporting in the
July 15 online
edition of
Nature Medicine.
"Normally, adult
human hearts do not
regenerate because
the heart doesn't
make more
cardiomyocytes
(heart muscle cells)
after injury,"
explained lead
researcher Dr.
Bernhard Kuhn, from
the Department of
Cardiology at
Children's Hospital
Boston. "It would be
desirable to induce
the heart to make
new cardiomyocytes
after injury."
To that end, Kuhn's
team created a patch
that contains a
compound called
periostin, which
helps cardiomyocytes
divide and multiply.
"If you do that over
a number of cycles,
you do get an
increase in
cardiomyocytes," he
said. "So, the
cardiomyocytes you
have lost are
replaced.
Periostin is a
natural component of
tissue surrounding
cells. It comes from
the skin lying
around bone and
helps stimulate
cells to divide.
During a heart
attack, cardiac
cells die from lack
of blood and oxygen.
This damage prevents
the heart from
working normally.
Typically, lost or
damaged cardiac
tissue cannot regrow.
In their
experiments, Kuhn's
team made patches
from a material
called Gelfoam and
soaked the patches
with periostin. They
placed the patches
on the damaged heart
muscle of rats in
which they had
induced a heart
attack.
After 12 weeks, the
rats treated with
the periostin patch
experienced a 16
percent improvement
in their heart's
cardiac pumping
ability. They also
had less scarring of
heart tissue, a
reduction in the
size of the damaged
area of the heart,
and more blood
vessels feeding the
area. In contrast,
rats that received a
patch without
periostin showed no
change in their
heart function.
|
The hearts of rats treated with
periostin showed a 100-fold
increase in the number of heart
cells and an average of 6
million more heart cells, far
outnumbering the amount of dying
cells.
The advantage of this technique
is that it doesn't require new
cells, such as stem cells, to
coax the growth of new heart
cells. Stem cells might also
migrate to other parts of the
body, with unknown consequences,
Kuhn said. The patch is "also
not gene-based, so it's not gene
therapy," he said
It
is possible that this same
technique could be used in
people who have severe heart
disease, Kuhn said. Although the
technique might not restore
heart function back to normal,
there could be significant
improvement, he said.
"At this point, the only
biologically proven myocardial
[heart] replacement therapy is
heart transplant," Kuhn said.
"But with this method, if you
were on a transplant list, you
may be able to come off it," he
said. "This could be a
revolutionary approach to
treating heart failure.
"The work is important in at
least two ways: It helps improve
our understanding of the
molecular pathways regulating
cell cycle reentry in adult
cardiomyocytes, and it can form
a basis for novel heart
therapies based on the
mobilization of [the heart's
own] cells," said Gordana
Vunjak-Novakovic, a professor of
biomedical engineering at
Columbia University Medical
Center in New York City and
co-director of the Tissue
Engineering Resource Center at
the U.S. National Institutes of
Health.
"This research nicely
demonstrates that periostin
induced cardiomyocytes' reentry
into the cell cycle," said Dr.
Gregg C. Fonarow, director of
the Ahmanson-UCLA Cardiomyopathy
Center at the University of
California Los Angeles.
Rather than needing to introduce
brand new cells into the damaged
heart, it may be possible to
induce existing cardiomyocytes
to grow and thus regenerate
normal functioning heart muscle,
said Fonarow, who is also
professor of clinical medicine
at UCLA.
"The ability to enhance cardiac
regeneration holds great promise
as novel treatment strategies
for [heart attack] complicated
by left ventricular dysfunction
and for chronic heart failure,"
he said."
|
But rat studies can only tell
scientists so much, Fonarow
added. "Additional studies with
adult human cardiomyocytes, and
ultimately clinical trials, are
needed," he said
http://heart.health.ivillage.com:80/
newsstories/patchhelpsheartgrownew
cells.cfm?nlcid=he|07-20-2007|
SOURCES: Bernhard Kuhn, M.D.,
department of cardiology, Children's
Hospital Boston; Gordana
Vunjak-Novakovic, Ph.D., professor,
biomedical engineering, Columbia
University Medical Center, New York
City, and co-director, Tissue
Engineering Resource Center, U.S.
National Institutes of Health,
Bethesda, Md.; Gregg C. Fonarow,
M.D., professor, clinical medicine,
and director, Ahmanson-UCLA
Cardiomyopathy Center, University of
California, Los Angeles; July 15,
2007, Nature Medicine online.
|
Quiz: Once High Blood
Pressure Develops, It Lasts
For a Lifetime. True
or False? |
The
answer
is true.
"Nearly
one in
three
American
adults
has high
blood
pressure.
Once
high
blood
pressure
develops,
it
usually
lasts a
lifetime.
The good
news is
that it
can be
treated
and
controlled.
A blood
pressure
of
140/90
or
higher
is
considered
high
blood
pressure.
Both
numbers
are
important.
If one
or both
numbers
are
usually
high,
you have
high
blood
pressure.
If you
are
being
treated
for high
blood
pressure,
you
still
have
high
blood
pressure
even if
you have
repeated
readings
in the
normal
range."
To
learn more about high blood
pressure, click below:
http://www.nhlbi.nih.gov/health/
dci/Diseases/Hbp/HBP_
WhatIs.html
Quiz: House Dust is a
Mixture of Potentially
Allergenic Materials That
Include Food Particles and
Flakes of Human Skin.
True or False? |
The
answer is True:
"House
dust is
a
component
of who
you are.
House
dust is
not just
dirt,
but a
mixture
of
potentially
allergenic
materials,
such as
food
particles,
mold
spores,
plant
and
insect
parts,
hair,
animal
fur,
dried
saliva
and
urine
from
pets,
and
flakes
of human
and
animal
skin.
Strategies
to
prevent
allergies
and
asthma
from
house
dust
include
dusting
rooms
thoroughly
with a
damp
cloth at
least
once a
week;
reducing
the
number
of
stuffed
animals,
wicker
baskets,
dried
flowers
and
other
dust
collectors
around
the
house;
and
replacing
heavy
drapes
and
blinds
with
washable
curtains
or
shades."
Source: National Institutes of
Health
|
