Rationale A growing number of patients with coronary disease have refractory angina. Preclinical and early-phase clinical data suggest that intramyocardial injection of autologous CD34+ cells can improve myocardial perfusion and function. Objective Evaluate the safety and bioactivity of intramyocardial injections of autologous CD34+ cells in patients with refractory angina who have exhausted all other treatment options. Methods and Results In this prospective, double-blind, randomized, phase II study (ClinicalTrials.gov identifier: NCT00300053), 167 patients with refractory angina received 1 of 2 doses (1×105 or 5×105 cells/kg) of mobilized autologous CD34+ cells or an equal volume of diluent (placebo). Treatment was distributed into 10 sites of ischemic, viable myocardium with a NOGA mapping injection catheter. The primary outcome measure was weekly angina frequency 6 months after treatment. Weekly angina frequency was significantly lower in the low-dose group than in placebo-treated patients at both 6 months (6.8±1.1 versus 10.9±1.2, P=0.020) and 12 months (6.3±1.2 versus 11.0±1.2, P=0.035); measurements in the high-dose group were also lower, but not significantly. Similarly, improvement in exercise tolerance was significantly greater in low-dose patients than in placebo-treated patients (6 months: 139±151 versus 69±122 seconds, P=0.014; 12 months: 140±171 versus 58±146 seconds, P=0.017) and greater, but not significantly, in the high-dose group. During cell mobilization and collection, 4.6% of patients had cardiac enzyme elevations consistent with non-ST segment elevation myocardial infarction. Mortality at 12 months was 5.4% in the placebo-treatment group with no deaths among cell-treated patients. Conclusions Patients with refractory angina who received intramyocardial injections of autologous CD34+ cells (105 cells/kg) experienced significant improvements in angina frequency and exercise tolerance. The cell-mobilization and -collection procedures were associated with cardiac enzyme elevations, which will be addressed in future studies.

To assess platelet function profiles in diabetic and nondiabetic patients on aspirin and clopidogrel therapy, two patient populations were included to investigate the 1) acute effects of a 300-mg clopidogrel loading dose (group 1, n ‫؍‬ 52) and 2) long-term effects of clopidogrel (group 2, n ‫؍‬ 120) on platelet function in diabetic compared with nondiabetic patients already on aspirin treatment. Patients were stratified according to the presence of type 2 diabetes. Platelet aggregation was assessed using light transmittance aggregometry (groups 1 and 2). Platelet activation (P-selectin expression and PAC-1 binding) was determined using wholeblood flow cytometry (group 2). Clopidogrel response was also assessed. In group 1, platelet aggregation was significantly increased in diabetic (n ‫؍‬ 16) compared with nondiabetic (n ‫؍‬ 36) patients at baseline and up to 24 h following a 300-mg loading dose (P ‫؍‬ 0.005). In group 2, platelet aggregation and activation were increased in diabetic (n ‫؍‬ 60) compared with nondiabetic (n ‫؍‬ 60) subjects (P < 0.05 for all platelet function assays). Diabetic subjects had a higher number of clopidogrel nonresponders (P ‫؍‬ 0.04). Diabetic patients have increased platelet reactivity compared with nondiabetic subjects on combined aspirin and clopidogrel treatment. Reduced sensitivity to antiplatelet drugs may contribute to the increased atherothombotic risk in diabetic patients. Diabetes 54:2430 -2435, 2005 D iabetes is commonly associated with accelerated atherosclerosis, clinically resulting in premature coronary artery disease (CAD), increased risk of cerebrovascular disease, and severe peripheral vascular disease (1). Patients with type 2 diabetes have a two-to fourfold increase in the risk of CAD, and diabetic patients without prior myocardial infarction have the same risk for a subsequent acute coronary event as nondiabetic patients with a previous myocardial infarction (2,3). Recurrent ischemic events are also more frequent in patients with type 2 diabetes than in nondiabetic patients (4 -6). Platelet dysfunction, among other mechanisms, contribute to the increased risk of atherothrombotic complications in the diabetic population (7-9). Such altered platelet function is revealed by hypersensitivity to aggregants observed in in vitro studies.Platelets from diabetic subjects are also less sensitive to aspirin (10 -11). Importantly, reduced sensitivity, or "poor response," to aspirin has been associated with an increased risk of ischemic events (12-15). Combining clopidogrel to aspirin enhances platelet inhibition and has been associated with a reduction in ischemic events compared with the use of aspirin alone (16 -19). However, the magnitude of antiplatelet effects may be depressed in diabetic patients. The aim of this study was to compare platelet function profiles in diabetic and nondiabetic patients on combined aspirin and clopidogrel therapy. RESEARCH DESIGN AND METHODSTwo patient populations were included to investigate the 1) acute effects of a 300-mg loading dose of...

Background-After treatment with clopidogrel, patients with type 2 diabetes mellitus (T2DM) have reduced platelet inhibition compared with patients who are not diabetic. Whether platelet inhibition can be enhanced by increasing clopidogrel maintenance dosage in T2DM patients is unknown. The aim of this pilot study was to assess the functional impact of a high maintenance dose in T2DM patients with suboptimal clopidogrel-induced antiplatelet effects. Methods and Results-T2DM patients on chronic dual antiplatelet therapy were screened to identify suboptimal clopidogrel responders. The latter were randomized to 30-day treatment with a standard (75 mg; nϭ20) or high (150 mg; nϭ20) daily maintenance dose. Platelet function was assessed at 3 time points: baseline, 30 days after randomization, and 30 days after resuming standard dosing. Platelet function parameters included adenosine diphosphate-induced (20 and 5 mol/L) maximal and late platelet aggregation, inhibition of platelet aggregation, platelet disaggregation, and P2Y 12 reactivity index. A total of 64 T2DM patients were screened to identify 40 suboptimal responders. After randomization, maximal adenosine diphosphate-induced (20 mol/L) platelet aggregation was significantly reduced in the 150-mg group compared with the 75-mg group (Pϭ0.002; primary end point). However, suboptimal clopidogrel response was still present in 60% of patients on the 150-mg regimen. All other platelet function parameters showed enhanced clopidogrel-induced antiplatelet effects with 150 mg, which returned to baseline values after resumption of standard dosing. Conclusions-A 150-mg maintenance dose of clopidogrel is associated with enhanced antiplatelet effects compared with 75 mg in high-risk T2DM patients. However, enhanced ex vivo platelet reactivity continues to persist, the clinical implications of which are unknown and need to be evaluated in large-scale clinical trials. (Circulation. 2007;115:708-716.)

High platelet reactivity determined in T2DM patients with coronary artery disease while on chronic dual antiplatelet therapy is associated with a higher risk of long-term adverse cardiovascular events, suggesting the need for tailored antithrombotic drug regimens in these high-risk patients.