A study for the treatment of heart failure after myocardial infarction found that the extract derived from bone marrow cells is as effective as therapy using bone marrow stem cells for improving cardiac function, decreasing the formation of scar tissue and improving cardiac pumping capacity after heart attack.
Findings are published in the Journal of Molecular Therapy.
The studies were done in mice using a novel stem cell delivery method developed by UCSF ( University of California - San Francisco ) researchers to show that the extract from bone marrow cells is as beneficial to cardiac function as are intact, whole cells. Both the cell and cell extract therapies resulted in the presence of more blood vessels and less cardiac cell death, or apoptosis, than no therapy. The study also showed that heart function benefited despite the finding that few of the injected cells remained in the heart at one month after therapy.
The medical literature is controversial as to whether bone marrow cells differentiate into cardiomyocytes, or cardiac muscle cells, but there is general agreement that stem cell therapy with these cells results in some level of functional improvement after a myocardial infarction. The exact mechanism for this is not yet clear.
The UCSF results confirm that whole cells are not necessarily required in order to see the beneficial effects of bone marrow cell therapy.
UCSF researchers are investigating these new therapies to improve cardiac function after myocardial infarction in an effort to prevent heart failure. Heart failure occurs when cardiac muscle is damaged and scar tissue replaces beating cardiomyocytes. As scar replaces healthy tissue, it causes the heart to enlarge and lose its pumping capacity. When the pumping capacity decreases, the heart fills with fluid, which moves to the lungs and can lead to organ failure and death.
Current therapies improve symptoms but do not replace scar tissue. The hope is to use stem cells to decrease the scar, minimize the loss of cardiac muscle and maintain or even improve the cardiac function after a heart attack.
Using a novel, closed-chest, ultrasound-guided injection technique developed by Yeghiazarians and his colleagues, the team administered three different groups with bone marrow cells, bone marrow cell extract, or saline ( for the control group ). The injections were administered at day three after heart attack, a timeframe somewhat similar to human biology on days six-to-seven after myocardial infarction.
The team found at day 28 that both the bone marrow cell group and the extract group had significantly smaller heart damage than the control group.
Left-ventricular ejection fraction ( LVEF ), or the measurement of blood pumped out of the ventricles per heart beat, fell uniformly in each group after heart attack from a level of about 57.2% to 38.4%. At day 28 ( and after the therapies had been administered on day three ), LVEF improved in both the bone marrow cell and extract groups to approximately 40.6% and 39.1% as compared to approximately 33.2% for the control group.
Source: University of California - San Francisco, 2009