New type of stem cells may help regenerate heart tissues
Adrienne Law (Contact)
Published: Monday, May 5, 2008
When cold, sweaty skin and pressure, burning and tightness in the
chest strikes, it could just be a sign of a heart attack.
But heart transplants, pacemakers and multiple types of drugs may not
be the only solution for fixing permanently damaged heart tissue post-
heart attack.
Last week, the scientific journal Stem Cells published a UCLA study
about stem cells that may regenerate different kinds of human
cardiovascular cells. The article, written by Dr. Robb MacLellan and
his colleagues at the David Geffen School of Medicine at UCLA, points
to a new type of stem cell that may be used to regenerate heart
tissue that dies during a heart attack because of a lack of blood
flow.
Induced pluripotent stem cells function like the more commonly used
embryonic stem cells, which are currently used in medical research to
clone cells from various parts of the human body.
Embryonic stem cells are undifferentiated – they are found early
enough in human development that they have yet to become liver cells
or lung cells, for example.
Those stem cells can thus be used to better understand the ways in
which organ systems develop and possible medical conditions that can
results from faulty development.
Induced pluripotent stem cells mimic signals similar to embryonic
stem cells found in human embryos, said Dr. Martin Pera, the director
of the Center for Stem Cell and Regenerative Medicine at the
University of Southern California.
"This (research) is an important step forward showing that these
cells can do what embryonic stem cells can do," he said.
But unlike embryonic stem cells, induced pluripotent stem cells do
not come from human embryos, and as such can help avoid many ethical
issues, he said.
Like embryonic stem cells, these stem cells can be used to regrow
organ system-specific tissue following an adverse medical event.
One of the more severe effects of a heart attack is dead heart
muscles that cannot be regrown during recovery. Instead, doctors can
use induced pluripotent stem cells to replace what is missing by
growing cardiac muscle cells and blood vessel cells, Pera said.
So far, studies have only been conducted on mice by transforming
mouse skin cells into induced pluripotent stem cells that could
eventually be made into multiple types of cardiovascular cells, said
Kathrin Plath, an assistant professor of biological chemistry and an
author of the study.
But researchers have faced challenges in constructing heart cells
from the cardiovascular cells they have cultivated because the
engineered cells need to integrate and beat in sequence with the
existing heart cells – something researchers have been observing
heart cells do in petri dishes, Pera said.
Researchers from UCLA, Harvard and Kyoto University in Japan
discovered these cells' potentially unique properties about a year
and a half ago, and they are hopeful that these new cells can make
the transition from petri dishes to patients, MacLellan said.
Induced pluripotent stem cells are particularly useful when
considering the effects of heart transplants on the human immune
system.
When patients undergo a heart transplant, their immune system can
potentially reject the new heart cells, MacLellan said.
Because transplant tissues may be read as foreign to the patient's
body, patients may have to take drugs that suppress the immune system.
Induced pluripotent stem cells might solve the problem of immune
system rejection, since patients would be able to use stem cells from
their own bodies, MacLellan said.
But while there are many possibilities of the function of these
special cells, there are limitations to bringing them to human
testing.
This class of stem cells are created by using retroviruses, harmful
viruses that could incorporate themselves and their genetic material
into a healthy cell's DNA.
Scientists have to be careful when injecting induced pluripotent stem
cells into subjects, MacLellan said.
While researchers are hopeful they will be able to use those stem
cells soon, it may take five to 10 years before scientists can
perform tests on human subjects, he said.
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may-help-regenerate
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StemCells subscribers may also be interested in these sites:
Children's Neurobiological Solutions
http://www.CNSfoundation.org/
Cord Blood Registry
http://www.CordBlood.com/at.cgi?a=150123
The CNS Healing Group
http://groups.yahoo.com/group/CNS_Healing
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