Ruth Pavelko lies in an operating suite that looks like the mission
control
center for a rocket launch. Interventional cardiologist Emerson Perin is
about
to inject stem cells into Pavelko’s weakened heart. Pavelko, a diabetic,
had
four heart attacks by the time she was 55. Blockage in major heart
blood
vessels, despite 13 attempts to keep them open, has left much of her
heart
muscle almost dead.
Patients with extremely advanced heart failure are eligible for some sort
of
assistive device, an artificial heart, or a transplant. Clinical trials at the
Texas
Heart Institute and several other sites now offer another option:
injection of
stem cells derived from her own bone marrow. Stem cells can
transform into
other cell types, including those that form blood vessels.
Images on color monitors and real-time X-rays are part of a technology
developed by Perin to distinguish living heart muscle from dead scar
tissue
inside the left ventricle of the heart. The left ventricle does most of the
work
of the heart, and most heart attacks and cases of heart failure involve
damage
to the left ventricle. Perin has now identified about 70 spots inside the
Pavelko’s left ventricle that are not contracting well, but still seem to be
viable. By the end of the surgery, about 1 million of her own stem cells
will
have been injected into those spots in her heart. She is one of 16
patients in
the first U.S. trial using stem cells derived from adult bone marrow to
reverse
advanced heart failure.
In 2000, the first trial of adult stem cells for the heart involved
extracting
stem calls from thigh muscle, not bone marrow. While early results
showed
improvements, but many patients eventually developed arrhythmias
(dangerous abnormalities in heart rhythm), presumably because thigh
muscle
contracts differently than heart muscle. A year later, Donald Orlick, a
scientist at the National Institutes of Health reported that stem cells
derived
from bone marrow and injected into mouse hearts improved function by
68%.
Important questions include whether injected stem cells actually change
into
heart muscle cells, whether they work by secreting powerful growth
factors,
or whether they change into new blood vessels.
Some scientists thought that clinical trials might be premature. Some
studies
suggested that stem cells could create scar tissue, thereby making
things
worse, not better. Other work showed that stem cells, if injected into
the
bloodstream, could clog small blood vessels, again possibly making
things
worse. Perin says that it’s easier to be cautious as a scientist than as a
physician. “They don’t have patients dying; I do.” After deciding that
direct
injection into scarless heart muscle was the best approach, Perin had
fine-
tuned his technology and was ready to go by the end of 2001.
The trial was risky. There were no published studies involving stem
cells in
multiple heart attack patients. His patients were very ill. One patient
was so
ill, he was gray in color, couldn’t breathe, and was starving. You can’t
eat if
you can’t breathe. His ejection fraction (a measure of the heart’s
pumping
ability) was 10%. Normal is 55%. A few viable areas of heart muscle
were
identified, but much of the left ventricle was dead. Another worry in
trials
like this; an early death during the study would end the trial. Perin took
a
chance and injected him. “I was really worried.” Five months later he
was
jogging on the beach. Before long, 13 of 14 patients had shown
significant
improvement.
Perin is not the only one doing stem cell research in heart patients.
Amit
Patel, a cardiac surgeon from the University of Pittsburgh has completed
three clinical trials in Asia and South America. He has seen an oveerall
increase in pumping ability from 26% to 46%, almost normal. Results he
describes as “unbelievable.”” Two publications are in the works. Johns
Hopkins is also starting clinical trials using stem cells in heart attack
patients.
The journal Circulation published Perin’s work in July.
Ruth Pavelko doesn’t read cardiac journals, but she knows something is
very
different in her heart. Before she received her stem cell injections, she
couldn’t walk to her mailbox. Today she climbs stairs many times a
day, and
once a week she makes the quarter-mile trip to a nearby park.