By Arshed Quyyumi, M.D.
Researchers still have a lot to learn about stem cells and how they function, including how they might be used to treat many different illnesses and medical conditions. But scientists, like myself, believe these cells hold the potential for great medical and scientific advances.
For example, our recent findings show that patients treated with their own bone marrow stem cells after a heart attack had increased circulation within the heart. Such progress in restoring the heart has given hope to doctors who want to help patients heal.
Stem cells function as a kind of repair system for the body. The basic term ’stem cell is’ used to describe a number of types of ‘undifferentiated’ cells that have the potential to become different kinds of specialized cells. By themselves, they lack the potential to carry out specific bodily tasks. For example, stem cells can’t act as neurons because they do not make the signaling chemicals that neurons use to communicate.
They have the ability, however, to make cells (called daughter cells) of more than one type. For example, certain blood stem cells can generate platelets, white cells and red blood cells. Stem cells also have the ability to self-renew, something that is unique to them. When stem cells divide, the new cells can be either new stem cells or more specialized types of functional cells.
People are often confused by references to ‘adult’ and ‘embryonic’ stem cells. ‘Adult’ here does not mean that they are from a person who is past puberty. Adult or somatic stem cells are found within tissues that have already differentiated. Embryonic stem cells are derived from a fertilized egg that has been maintained in a lab and allowed to divide to a particular early embryonic stage called the blastocyst.
In our heart study, we are obtaining cells from the bone marrow, which has been known for many years to contain particular kinds of stem cells. When someone with leukemia receives a bone marrow transplant, the bone marrow stem cells restore that patient’s ability to make new blood cells. We are looking at whether bone marrow cells can also help repair the blood vessels that sustain the heart muscle.
A heart attack deprives the heart tissue of oxygen, killing cardiac muscle cells. This can cause formation of scar tissue and a decreased ability of the heart to pump blood. The burden on the viable cells that remain can lead to heart failure, and eventual death. Restoring damaged heart tissues, through repair or regeneration, is therefore a hopeful new strategy to treat heart failure.
One doctor can’t do this alone, and the research can cross academic disciplines. Our work for the heart study was conducted with Dr. Edmund Waller, Emory professor of hematology and medical oncology. Our findings reported at the American College of Cardiology meeting showed that patients receiving higher doses of cells had greater improvement in blood flow within the heart than those patients treated with lower doses or those receiving medication alone.
The results show that treatment with bone marrow stem cells has the potential to reduce long-term complications after a heart attack. We are very excited about this progress and are planning new research on how we can help patients with this form of treatment in the future.
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