No abstract

Background-Intracoronary transfer of autologous bone marrow cells (BMCs) promotes recovery of left ventricular systolic function in patients with acute myocardial infarction. Although the mechanisms of this effect remain to be established, homing of BMCs into the infarcted myocardium is probably a critical early event. Methods and Results-We determined BMC biodistribution after therapeutic application in patients with a first ST-segment-elevation myocardial infarction who had undergone stenting of the infarct-related artery. Unselected BMCs were radiolabeled with 100 MBq 2-[ 18 F]-fluoro-2-deoxy-D-glucose ( 18 F-FDG) and infused into the infarct-related coronary artery (intracoronary; nϭ3 patients) or injected via an antecubital vein (intravenous; nϭ3 patients). In 3 additional patients, CD34-positive (CD34 ϩ ) cells were immunomagnetically enriched from unselected BMCs, labeled with 18 F-FDG, and infused intracoronarily. Cell transfer was performed 5 to 10 days after stenting. More than 99% of the infused total radioactivity was cell bound. Nucleated cell viability, comparable in all preparations, ranged from 92% to 96%. Fifty to 75 minutes after cell transfer, all patients underwent 3D PET imaging. After intracoronary transfer, 1.3% to 2.6% of 18 F-FDG-labeled unselected BMCs were detected in the infarcted myocardium; the remaining activity was found primarily in liver and spleen. After intravenous transfer, only background activity was detected in the infarcted myocardium. After intracoronary transfer of 18 F-FDG-labeled CD34-enriched cells, 14% to 39% of the total activity was detected in the infarcted myocardium. Unselected BMCs engrafted in the infarct center and border zone; homing of CD34-enriched cells was more pronounced in the border zone. Conclusions-18 F-FDG labeling and 3D PET imaging can be used to monitor myocardial homing and biodistribution of BMCs after therapeutic application in patients.

In contrast to donor T cells, natural killer (NK) cells are known to mediate anti-cancer effects without the risk of inducing graft-versus-host disease (GvHD). In order to improve cytotoxicity against resistant cancer cells, auspicious efforts have been made with chimeric antigen receptor (CAR) expressing T- and NK cells. These CAR-modified cells express antigen receptors against tumor-associated surface antigens, thus redirecting the effector cells and enhancing tumor-specific immunosurveillance. However, many cancer antigens are also expressed on healthy tissues, potentially leading to off tumor/on target toxicity by CAR-engineered cells. In order to control such potentially severe side effects, the insertion of suicide genes into CAR-modified effectors can provide a means for efficient depletion of these cells. While CAR-expressing T cells have entered successfully clinical trials, experience with CAR-engineered NK cells is mainly restricted to pre-clinical investigations and predominantly to NK cell lines. In this review we summarize the data on CAR expressing NK cells focusing on the possible advantage using these short-lived effector cells and discuss the necessity of suicide switches. Furthermore, we address the compliance of such modified NK cells with regulatory requirements as a new field in cellular immunotherapy.

A single intracoronary application of BMCs does not promote a sustained improvement of LVEF in STEMI patients with relatively preserved systolic function. It is conceivable that a subgroup of patients with more transmural infarcts may derive a sustained benefit from BMC therapy. However, this needs to be tested prospectively in a randomized trial.

Background-Intracoronary transfer of autologous bone marrow cells (BMCs) may enhance recovery of left ventricular (LV) function in patients after acute myocardial infarction (AMI). However, clinical studies addressing the effects of BMCs after AMI have covered only limited time frames ranging from 3 to 6 months. The critical question of whether BMC transfer can have a sustained impact on LV function remains unanswered. Methods and Results-After percutaneous coronary intervention with stent implantation (PCI) of the infarct-related artery, 60 patients were randomized 1:1 to a control group with optimal postinfarction therapy and a BMC transfer group that also received an intracoronary BMC infusion 4.8Ϯ1.3 days after PCI. Cardiac MRI was performed 3.5Ϯ1.5 days, 6Ϯ1 months, and 18Ϯ6 months after PCI. BMC transfer was not associated with adverse clinical events. In the control group, mean global LV ejection fraction increased by 0.7 and 3.1 percentage points after 6 and 18 months, respectively. LV ejection fraction in the BMC transfer group increased by 6.7 and 5.9 percentage points. The difference in LVEF improvement between groups was significant after 6 months but not after 18 months (Pϭ0.27). The speed of LV ejection fraction recovery over the course of 18 months was significantly higher in the BMC transfer group (Pϭ0.001). Conclusions-In this study, a single dose of intracoronary BMCs did not provide long-term benefit on LV systolic function after AMI compared with a randomized control group; however, the study suggests an acceleration of LV ejection fraction recovery after AMI by BMC therapy. (Circulation. 2006;113:1287-1294.)