The bone marrow cells came from patients' own blood and were injected into their ailing hearts. The cells fueled new cell growth, which strengthened the heart's pumping capacity.
"These results demonstrate for the first time that transplantation of a person's own stem cells through direct intracoronary injection increased cardiac function, blood flow and metabolism in the damaged zone," said senior author Bodo E. Strauer, M.D., professor of medicine at Heinrich Heine University in Düsseldorf, Germany.
"If a prospective, randomized, multicenter study confirms these encouraging results, a new therapy for heart attacks could be in reach," he said.
When a person suffers a heart attack, the heart can develop left ventricular remodeling, a process by which heart muscle cells stretch in response to damage. Over time, the stretched muscle weakens and can lead to heart failure.
In March 2001, in a first-of-its-kind procedure, Strauer and his colleagues treated an acute heart attack patient with stem cells harvested from his own bone marrow. The cells were implanted into the damaged muscle, using a catheter threaded into a heart artery.
Three months later, the patient had less heart muscle damage and an increased ejection fraction, a measure of the heart's pumping ability.
The study reported today is a follow-up to that small trial.
The German team enrolled 40 heart attack patients who had been treated with balloon angioplasty and also had a mesh tube called a stent placed into the vessel to help prop it open.
Twenty patients agreed to accept the stem cells; 20 others who declined the experimental procedure comprised the control group.
All patients had angiography and a similar imaging examination called left ventriculography to assess their heart's geometry. These exams were given before enrollment and three months later.
Four to eight days after the patients' heart attacks, doctors obtained bone marrow cells from members of the treatment group. Stem cells were isolated from the marrow, cultured overnight, and transplanted the following day.
A catheter was pushed into the blocked heart artery that caused the heart attack and balloon angioplasty was performed for two to four minutes. Small amounts (3 - 4 mL) of a solution containing the stem cells were infused into the damaged heart tissue at the re-opened site four or five times.
After three months, the stem cell patients' average area of damage decreased from 33 percent of the left ventricle's circumference to 14 percent.
The contraction speed of the heart went from 1.5 centimeters per second (cm/s) in the treated group to 3.3 cm/s. The fraction of blood ejected by the heart rose from 55 percent to 65 percent.
Ten patients had a test that measures the average glucose uptake, which indicates the metabolism rate of cells. Their glucose uptake increased from 47 percent to 58 percent. The amount of blood perfusing the damaged area rose from 49 percent to 58 percent.
The team said these improvements indicate that the transplanted stem cells are associated with new heart muscle and new blood vessels.
Several research teams have investigated the use of stem cells harvested from bone marrow to reverse the muscle damage caused by a heart attack. Stem cells are immature cells that still can transform, or differentiate, into different types of cells, such as heart muscle and blood vessels.
"Bone-marrow-derived stems cells offer one approach to reverse remodeling of the heart," Strauer said. Co-authors are Michael Brehm, M.D.; Tobias Zeus, M.D.; Matthias Köstering, M.D.; Christine Antke, M.D.; Gesine Kögler, Ph.D.; Hans-Werner Müller, M.D. and Peter Wernet, M.D.
Note: Presentation time is 8:30 a.m. EST, Monday, Nov. 10, 2003
Note: This abstract will be featured in a news conference.