Bone marrow stem cells help mend broken hearts
Human trials yield promising results
27 April 2004
HELEN R. PILCHER
Bone marrow-derived stem cells may help damaged heart
muscle to regrow
© Andrew Leonard / Science Photo Library
Stem cell therapy might help repair ailing hearts, a clinical
Researchers harvested stem cells from patients with cardiac
failure, and then transplanted the cells into their damaged hearts.
Six months later, the hearts functioned significantly better than
those of patients who had not received the therapy.
The results suggest that stem cell transplants are a good way to
treat heart failure, researchers told the American Association for
Thoracic Surgery meeting in Toronto this week.
But the study will fuel the ongoing debate over the usefulness of
stem cell therapy for cardiac problems. Animal and human studies
have yielded conflicting results, leading some to question the
effectiveness and safety of the technique.
Amit Patel from the University of Pittsburgh School of Medicine
and colleagues studied 20 patients undergoing bypass surgery for
heart failure in South America. Half received stem cell therapy, in
which adult stem cells were harvested from the patientís own bone
marrow and then injected into the heart.
Patients received up to 30 injections into sites where there was
obvious muscle damage. Subsequently, their hearts were able to pump
more blood than those who had surgery alone.
It is thought that the stem cells help damaged heart muscle to
regrow and may also stimulate the formation of new blood vessels.
Recipients also had higher levels of a protein called connexin
43, which is important for cell communication. "We do not know if
this increase was due to the growth of new heart muscle cells
resulting from the stem cell injections or whether the stem cells
coaxed existing cells to come out of hibernation," says Patel.
Critically, there seemed to be no side-effects or complications.
Earlier this year, a stem cell trial in South Korea was halted after
some heart attack patients began to develop abnormal growths in
The study is also at odds with earlier rat studies, says stem
cell researcher Malcolm Alison from Imperial College London. A few
months ago, two teams concluded that stem cells transplanted into
damaged rat hearts were unable to replace heart cells.
An estimated 23 million people worldwide are affected by heart
failure. The South American trials are continuing.