Human stem cells turned into heart cells
2001-08-02 12:59
Washington - Scientists said on Wednesday that
they had grown heart cells from human embryonic stem cells, an
important step toward harnessing the transformational qualities
of these primitive master cells to regenerate tissue damaged by
cardiac disease.
Israeli researchers said they had created early-stage human
heart cells in petri dishes using stem cells derived from an
embryo just days after fertilisation. They said they envisioned
using these cells, after refining the process, to reverse
damage inflicted on cardiac muscle by heart attacks.
"It was shown for the first time definitely that the cells
that are being created are cardiac cells that show electrical,
biochemical and morphological characteristics of early or young
cardiac muscle," Dr Joseph Itskovitz-Eldor, of the Faculty of
Medicine and Rambam Medical Centre in Haifa, said in a
telephone interview.
The publication of the study in the Journal of Clinical
Investigation comes as US President George W. Bush considers
whether to permit federal funding of research involving human
embryonic stem cells.
Embryonic stem cells can be viewed as the body's early
building blocks. Their wondrous ability to transform themselves
into virtually every cell type enables the embryo to grow from
a round ball of a few cells into a fully formed body.
Researchers are hoping to use stem cells to create
therapies for a variety of illnesses, including heart
disease--one of the leading causes of death worldwide.
"The idea is that if you now have a source for heart cells,
in the future you can transplant them into a non-functioning
area (of the heart) and possibly replace the cells," said study
co-author Dr Lior Gepstein of the Technion-Israel Institute of
Technology Faculty of Medicine.
"When we have a heart attack, the area of the heart that
doesn't receive blood supply actually dies and is replaced by
scar tissue," Gepstein added. "Because the adult heart doesn't
have any regeneration capacity, this area in the heart won't
contract anymore (to pump blood). So this can lead to
deterioration in heart function and eventually to heart
failure."
The goal would be to inject the early-stage human heart
cells created in the laboratory using stem cells into the
damaged area and create healthy cardiac muscle that restores
heart function, the researchers said.
Other scientists recently reported they had used mouse stem
cells to create mouse cardiac cells.
The Israeli researchers used human embryonic stem cells to
grow an undifferentiated mass of cells using a standard
laboratory technique. They then sought to steer the multiplying
cells toward transformation into cardiac cells by optimising
the conditions in the petri dish.
As the cells divided, the cells aggregated into microscopic
clumps. In about 10% of these, the investigators detected small
groups of cells that were contracting spontaneously just like
cardiomyocytes - the cells that develop into heart tissue in an
embryo.
The researchers then put these groups of cells through a
battery of tests to confirm that they were cardiomyocytes and
thus destined to differentiate into mature heart cells.
The report indicates that the cells checked out in every
way, including the genes they activated, the proteins they
possessed, their electrical activity as they regularly
contracted like a beating heart, their use of calcium and their
response to hormones such as adrenaline.
"These are heart cells," Gepstein said.
He said the researchers still needed to devise a way to
increase the number of these cells produced in the laboratory.
Noting that 90% of the cells created in the experiment were not
heart cells, he said the researchers were exploring different
combinations of chemicals to induce the stem cells to produce
pure cultures of cardiomyocytes.
The researchers said several million of these cells would
be needed for a theoretical transplantation.