The Hopkins team expects that after injection, the adult stem cells will migrate to the damaged areas of the heart muscle, responding to chemical signals released by the heart after an infarct that triggers a repair response from the bone marrow.
Related clinical research under way in China also uses adult stem cells, but they come directly from the patient, and no universal donor is used as in the Hopkins study.
It remains unclear from earlier animal studies how or why the adult stem cells develop into new and healthy heart tissue, or exactly how long their healing effects last.
Adult stem cells are being 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 for use in this study. While their precise biological action is not known, mesenchymal bone marrrow stem cells are known to give rise to a variety of cell types, including bone, cartilage, fat, and other kinds of connective tissue cells such as those in tendons, as well as muscle, such as the heart. A stem cell is a special type of body cell that gives rise to other types of specialized cells.
"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," notes Hare. "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.
"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 surroundi
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Contact: David March
dmarch1@jhmi.edu
410-955-1534
Johns Hopkins Medical Institutions
25-Mar-2005