More than 1.5 million heart attacks, or acute myocardial infarctions (AMI), occur each year in the United States – one every 20 seconds. An important factor in the ultimate prognosis for AMI survivors is the amount of damage to the myocardium – the middle layer of the wall of the heart composed of cardiac muscle fibers that allow the heart to contract.
In experiments on animals, implantation of progenitor cells – specialized stem cells derived from the bone marrow or circulating blood and grown in culture – regenerated damaged tissue and improved cardiac function after AMI. The success of these experiments led this group of researchers to evaluate the effect of progenitor cell therapy on humans, using F-18-DG-PET and T1-201-SPECT technology. The study included 14 patients averaging 55 years of age who received infusions of progenitor cells four days after AMI; 6 patients received cells derived from bone marrow, while the other 8 received cells originating from circulating blood.
The scientists used mean signal intensity (MSI) to measure the viability of the implanted cells, taking baseline scans after implantation and then repeating the scans four months later. In 11 of 14 patients, the MSI in areas with AMI damage increased significantly according to both PET and SPECT scans, with no discernible difference due to the type of progenitor cells used. The researchers also monitored non-damaged areas to compare the MSI levels. By using nuclear medicine technology, Döbert and her colleagues were able to conclude that, “transplantation of progenitor cells has a positive effect of myocardial viability after acute myocardial infarction.”