Biologia

Stem Cell Therapy Effectively Treats Heart Attacks In Animals1
ScienceDaily
Johns Hopkins Heart Institute1

Results from an animal study conducted at Johns Hopkins show that stem cell therapy can be used effectively to treat heart attacks, or myocardial infarcts, in pigs. Stem cells taken from another pig’s bone marrow, when injected into the animal’s damaged heart, were able to restore theheart’s function to its original condition.

If further animal studies and human clinical trials prove equally successful, the Hopkins researchers believe this could be a new, widely applicable treatment to repair and reverse the damage done to heart muscle that has been infarcted, or destroyed, after losing its blood supply. Nearly 8 million Americans alive today have suffered at least one heartattack and so are at greater risk for chronic heart failure or another, potentially fatal, heart attack.
“Current treatments for cardiovascular disease prevent heart attack from occurring and/or alleviate its after-effects, but they do not repair the damaged muscle that results, leaving sizably dead portions of heart tissue that lead to dangerous scars in the heart,” said cardiologist JoshuaHare, M.D., professor of medicine at The Johns Hopkins University School of Medicine and its Heart Institute, and lead author of the study to be presented at the American Heart Association’s Scientific Sessions 2004 on Nov. 9.
“Damage done by a heart attack to heart muscle is really the cause of all the serious complications of the disease: Disturbances of heart rhythm can lead to sudden cardiacdeath and decreased muscle pumping function can lead to congestive heart failure,” said study co-author and interventional cardiologist Alan Heldman, M.D., assistant professor of medicine at Hopkins, who performed the injection procedures. “Our aim is to find a way to repair the damage done to the heart muscle and prevent these complications.”
In a controlled study of 14 pigs (whose circulatorysystems are similar to humans), seven received therapy and another seven did not. The researchers found that injections of bone marrow, or “adult,” stem cells directly into heart muscle, recently damaged by a heart attack, produced a nearly full recovery after a relatively short period of time, two months.
Recovery was measured for the seven treated animals as full restoration of heart musclecontraction to levels existing prior to infarction. Indeed, dead scar tissue nearly disappeared after therapy, which produced mostly healthy, normal-looking heart tissue and left only a small trace of the heart attack, the researchers said.
In contrast, for the seven animals in the control group that did not receive therapy but were injected, instead, with placebo, no recovery was observed and theanimals’ condition worsened, leading to the development of congestive heart failure within two months after heart attack.
In order to thoroughly cover the area of damaged heart muscle - approximately the size of a one-dollar coin - researchers gave every treated animal between 12 and 15 microscopic injections of adult stem cells, each injection containing nearly 200 million cells.
The cells wereinjected directly into the heart muscle using a specialized catheter inserted through a tiny puncture in an artery, a procedure similar to other cardiac catheterization techniques. Use of this catheterization technique was shown to be safe and effective. Its use increases the options for delivering stem cell therapy in the future; most existing studies use intravenous injections.
It remains unclearhow or why the adult stem cells developed into new and healthy heart tissue, or exactly how long their healing effects last.
Adult stem cells were used because they are readily available from the bone marrow, where they are plentiful. A special kind of bone marrow stem cell, called a mesenchymal stem cell, was separated from other kinds and used in this study. While their precise biological...