Cardiac stem cells — even in elderly and sick patients — could generate new heart muscle and vessel tissue and be used to treat heart failure, reports Domenico D’Amario, from the Center for Regenerative Medicine at Harvard University (Massachusetts, USA), and colleagues.  Scientists surgically removed tissue from the muscular wall of the heart’s chambers in 21 patients. They then isolated and multiplied the cardiac stem cells (CSCs) found there. Most of the patients had ischemic cardiomyopathy (enlarged and weakened muscle due to coronary artery disease). Eleven also had diabetes. The average age of patients was about 65.  The researchers also examined stem cells’ biological properties that would influence their therapeutic value. They found that cells had long telomeres, or “caps,” on their chromosomal ends indicating that expanded CSCs retained a significant growth reserve, although less so in older or diabetic patients. As well, the scientists studied activation of a cell surface marker, insulin growth factor receptor 1 (IGF-1R), which recognizes stem cells that are most likely to thrive and have the potential to produce new cardiac tissue.