Myocardial infarction (heart attack) can occur as a result of diminished blood supply to the heart muscles. It can happen as a result of atherosclerosis of the coronary arteries,which supplies blood to the heart muscles or myocardium. For many a years and even now the first line of treatment opted is angioplasty and the placement of stents to keep the ateries patent. But even with surgery,drugs,organ transplantations, and placement of mechanical devices,a large proportion of the patients die withi five years of the initial episode. So researches were made to find a lasting solution to the heart ailment. The latest breakthrough in the cardiac research study is that adult and primitive stem cells may be capable to replace damaged myocardial cells and generate new blood vessels in the damaged area to restore the affected supply. So scientists and physicians across the world are now trying to save additional lives by the use of these cells to replace the damaged cardiomyocytes and thereby give back the heart its original pumping vigor.
Several trials were conducted to find out the best source for stem cells which differentiate to potential cardiomyocytes. Skeletal myoblast cells were studied thoroughly but these were not found to mature to functional cardiomyocyes moreover these were found to have an arrythmogenic effect on the heart. Thereafter bone marrow cells and peripheral blood stem cells were studied.These contained hemopoetic stem cells,mesenchymal stem cells, and endothelial progenitor cells. The cell harvesting from bone marrow is a pretty invasive task.Another alternative was to use G-CSF (Granulocye Colony Stimulating Factor) to migrate the peripheral blood cells from bone marrow to the heart. Needless to say this also has its defects because several other immune cells also migrate to the area causing inflammation. So which method is use to transfer the stem cells to the affected site?
In a study conducted with three patient groups who underwent percutaneous coronary stenting of the ifarct related artery.The first group recieved intracoronary infusion of peripheral blood cells by catheter induced technique. The second group had G-CSF to induce mobilization of peripheral stem cells to the site and the third group served as a control. In the results the first group showed marked exercise tolerance and improved cardiac function compared to the other two groups.
Stem cells not only improve function of the myocardial cells, but they promote cadiac perfusion of the myocardium as these stem cell have the ability to generate new blood vessels too.
Let us examine how the procedure is done. Through a surgiacal procedure stem cells are transfered to the infarcted myocardium via a catheter. Later it has been found that these cells differentiate to functional myocytes and also improve the cardiac perfusion by releasing cytokines that induce angiogenesis.
The Unseen Challenges
Though stem cell therapy was seen as aboon to patients with heart ailments,there are many more hurdles to be overcome.One major setback is the restenosis seen in patients who already has a stent to cover up the damaged coronary artery and these were seen in patients who received intracoronary treatment. The degree of neointimal growth was proportional to the improvements made in cardiac function. These setbacks could be overcome by timely management by the professionals through drug-eluting stents.However this serves as a first warning to expect more obstacles in this therapy. Another drawback is that the long term effects of stem cell therapy has not been evaluated yet. We can hope that more researches in cell and gene therapy will bring more and more deadly diseases under the control of medical therapy.