A new study at Johns Hopkins aims to test the safety of injecting adult stem cells after a heart attack. This is believed to be the first clinical trial in the United States in which adult mesenchymal stem cells are being used to repair muscle damaged by heart attack. Lead study investigator Joshua Hare, M.D., a professor of medicine at The Johns Hopkins University School of Medicine's Heart Institute, states that the treatment approach is aimed at repairing damage that can leave dead portions of heart tissue.
He claims, "This is an important milestone on the journey to better cardiovascular care and to realization of the promise of adult stem cell research."
Previous research in animals has indicated that the injection of adult stem cells into the heart muscle can restore the heart to its original condition within two months.
In Nov. 2004, Hopkins researchers showed that only 25 percent of dead scar tissue remained following treatment with adult stem cells. Overall, the injection of adult stem cells produced a healthy heart tissue.
The subjects of this study include 48 adults who had their first heart attack within ten days of trial enrollment. It is a double bind study, meaning neither researchers nor patients will know who received the stem cell treatment until the end of the study.
Patients will be assigned randomly to one of four groups. Each group will consist of 12 patients, each receiving either an injection of adult stem cells or a placebo. Three groups will receive different preset doses of stem cell therapy, while the last group will receive a placebo. Participants will be monitored for two years in order to determine whether the injections are safe and whether they produce any side effects.
Researchers predict that the adult stem cells will move to and repair the damaged areas of the heart muscle, following injection. The adult bone marrow stem cells will do this by responding to the chemical signals that are released by the heart after a heart attack.
The adult stem cells to be used in this study are not from the patients. Mesenchymal stem cells are being used in this clinical trial. These stems cell give rise various cell types, including bone, cartilage, fat and muscle.
Dr. Hare states, "Using mesenchymal stem cells also avoids potential problems with immunosuppression, in which every human's immune system might attack stem cells from sources other than itself. Because they remain in an early stage of development, mesenchymal stem cells do not trigger an immune response, unlike what would happen if more developed stem cells were used."
He adds, "While the bone marrow adult stem cells do not have the same potential to develop into different organ tissues as do embryonic stem cells, the use of adult stem cells in this study shows their tremendous potential in developing effective therapies for heart disease, and avoids the controversy surrounding destruction of embryos to obtain the embryonic variety."
It is estimated that seven million Americans have suffered from at least one heart attack. This places them at a greater risk for heart failure.
"Current approaches to cardiovascular disease can prevent heart attack or alleviate its after-effects, but they have not included repair of damage that leaves sizably dead portions of heart tissue as dangerous scars in the heart," says study co-investigator and cardiologist Steven Schulman, M.D., who is a professor at Hopkins as well as the director of the coronary care unit at The Johns Hopkins Hospital.
The trial is being supported by Baltimore-based Osiris Therapeutics, which developed the stem cell product.
