Intraoperative CD133+ cell transplantation during coronary artery bypass grafting in ischemic cardiomyopathy.

If traditional treatment of coronary artery disease has failed, intramyocardial transplantation of CD133+ stem cells with the potential to improve myocardial function is an alternative approach to treating ischemic cardiomyopathy. The INSTEM trial aims at evaluating safety and feasibility of isolation and subsequent intramyocardial transplantation of CD133+ cells in combination with coronary artery bypass grafting (CABG). Patients suffering from severe ischemic cardiomyopathy (ejection fraction ≫15% and ≪35%) are enrolled in this trial. Bone marrow is harvested from the iliac crest and CD133+ cells are purified up to 99%. The myocardial region of interest is pre-treated by transmyocardial laser revascularization in order to trigger homing of transplanted cells. Autologous bone marrow CD133+ cells (up to 30×10(6) cells) are injected into predefined myocardial regions. Cardiac function prior to as well as three, six and 12 months after cell transplantation is assessed by echocardiography. Neither operative mortalities nor any cardiac deaths during follow-up occurred. Left ventricular ejection fraction improved from 25%±5% preoperatively to 40%±8% after six months. Our method of intraoperative CD133+ cell isolation while performing CABG and subsequent transmyocardial cell transplantation is feasible and safe. Although the follow-up has not yet been completed we propose this procedure to be a promising causal therapy of severe ischemic cardiomyopathy.