G-CSF in patients suffering from late revascularised ST elevation myocardial infarction: final 1-year-results of the G-CSF-STEMI Trial.

AIMS: The aims of this trial were to investigate the effect of granulocyte colony-stimulating factor (G-CSF) on left-ventricular ejection fraction and event-free survival in patients suffering from sub-acute myocardial infarction (STEMI). METHODS: We enrolled 44 patients suffering from sub-acute STEMI with late revascularization achieved by percutaneous coronary intervention (PCI). Patients were randomized to receive either G-CSF (Filgrastim) at a dose of 10 µg/kg body weight/day subcutaneously or placebo. Changes of global and regional cardiac function from baseline (1 week after PCI) over 1 and 3 months to 12 months of follow-up were analyzed by magnetic resonance imaging. RESULTS: Ejection fraction improved in G-CSF treated patients from 41.1±11.9% to 47.1±11.9% (3 months) and decreased slightly to 45.7±15.1% after 1 year. Ejection fraction also improved in the placebo group from 43.8±9.0% to 49.5±11.8% (3 months) and decreased slightly to 42.9±15.4% after 1 year (1 year MRI follow-up was performed in 23 out initial 44 patients). There was no significant difference between the two groups at any time point. Other parameters such as infarct size, myocardial perfusion, left ventricular end-diastolic and end-systolic volumes were not different between the two groups. Event-free survival of such as death, (re) myocardial infarction or acute coronary syndromes, coronary artery bypass grafting and target lesion revascularization was not significantly different between both groups. CONCLUSIONS: G-CSF administration after sub-acute STEMI is feasible and safe but does not improve myocardial function or survival when used as a single substance.

G-CSF in patients suffering from late revascularized ST elevation myocardial infarction: analysis on the timing of G-CSF administration.

OBJECTIVE: Granulocyte colony-stimulating factor (G-CSF) improves myocardial function after infarction in vivo. Placebo-controlled clinical studies failed to show beneficial effects on myocardial function. Recent data demonstrate that the time point of treatment initiation may be crucial for the efficacy of G-CSF. We investigated the influence of the timing of G-CSF treatment on myocardial function and perfusion in a subgroup study of the G-CSF-ST Elevation Myocardial Infarction trial. MATERIALS AND METHODS: Patients with late revascularized myocardial infarction (n = 44) were treated with either G-CSF or placebo over 5 days after successful percutaneous coronary intervention (PCI). Of the G-CSF group, 13 patients had received G-CSF early treatment started within 24 hours after PCI (mean: 16 +/- 6 hours). In 10 patients, G-CSF was initiated late (>24 hours after PCI, mean: 49 +/- 26 hours). Global and regional myocardial function and perfusion were assessed from baseline to 3 months after PCI using magnetic resonance imaging in 37 patients who completed magnetic resonance follow-up. RESULTS: G-CSF was safe when used early or late after PCI. Early G-CSF administration resulted in significantly improved perfusion at rest 1 month after PCI when compared to placebo (Up-slope, signal intensity 1.2 [0.4-1.8] vs 0.6 [0.1-1.3], p = 0.03). Timing of G-CSF had no influence on global and regional function. CONCLUSION: This post-hoc analysis indicates that timing of G-CSF after myocardial infarction does not improve myocardial function but myocardial perfusion if the cytokine is given early. This urges the need to investigate alternative dosage regimens or combination with novel therapeutics promoting mobilization and homing.

Autologous bone marrow stem cell mobilization induced by granulocyte colony-stimulating factor after subacute ST-segment elevation myocardial infarction undergoing late revascularization: final results from the G-CSF-STEMI (Granulocyte Colony-Stimulating Factor ST-Segment Elevation Myocardial Infarction) trial.

OBJECTIVES: The purpose of this investigator-driven, prospective, randomized, double-blinded, placebo-controlled phase II study was to compare the effects of granulocyte colony-stimulating factor (G-CSF) on the improvement of myocardial function in patients undergoing delayed percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI). BACKGROUND: Experimental and early clinical studies suggest that transplantation of stem cells improves cardiac regeneration and neovascularization after acute myocardial infarction. Most investigators have utilized either a direct injection or intracoronary infusion of bone marrow-derived cells, but early cytokine-mediated mobilization of stem cells has been reported to show similar improvement in cardiac function. METHODS: Forty-four patients with late revascularized subacute STEMI were treated either with G-CSF or placebo over 5 days after successful PCI. Primary end points were change of global and regional myocardial function from baseline (1 week after PCI) to 3 months after PCI assessed by magnetic resonance imaging (MRI). Secondary end points consisted of characterization of mobilized stem cell populations, assessment of safety parameters up to 12 months including 6-month angiography, as well as myocardial perfusion assessed by MRI. RESULTS: Global myocardial function from baseline (1 week after PCI) to 3 months improved in both groups, but G-CSF was not superior to placebo (Delta(ejection fraction) 6.2 +/- 9.0 vs. 5.3 +/- 9.8%, p = 0.77). A slight but non-significant improvement of regional function occurred in both groups. Granulocyte colony-stimulating factor resulted in mobilization of endothelial progenitor cell populations and was well tolerated with a similar rate of target lesion revascularization from in-stent restenosis. In both groups major adverse cardiovascular events occurred in a comparable frequency. Granulocyte colony-stimulating factor resulted in significant improvement of myocardial perfusion 1 week and 1 month after PCI. CONCLUSIONS: Granulocyte colony-stimulating factor treatment after PCI in subacute STEMI is feasible and relatively safe. However, patients do not benefit from G-CSF when PCI is performed late. Granulocyte colony-stimulating factor results in improved myocardial perfusion of the infarcted area, which may reflect enhanced neovascularization.

Uptake of polyamines by the unicellular green alga Chlamydomonas reinhardtii and their effect on ornithine decarboxylase activity.

Uptake of exogenous polyamines by the unicellular green alga Chlamydomonas reinhardtii and their effects on polyamine metabolism were investigated. Our data show that, in contrast to mammalian cells, Chlamydomonas reinhardtii does not contain short-living, high-affinity polyamine transporters whose cellular level is dependent on the polyamine concentration. However, exogenous polyamines affect polyamine metabolism in Chlamydomonas cells. Exogenous putrescine caused a slow increase of both putrescine and spermidine and, vice versa, exogenous spermidine also led to an increase of the intracellular levels of both spermidine and putrescine. No intracellular spermine was detected under any conditions. Exogenous spermine was taken up by the cells and caused a decrease in their putrescine and spermidine levels. As in other organisms, exogenous polyamines led to a decrease in the activity of ornithine decarboxylase, a key enzyme of polyamine synthesis. In contrast to mammalian cells, this polyamine-induced decrease in ornithine decarboxylase activity is not mediated by a polyamine-dependent degradation or inactivation, but exclusively due to a decreased synthesis of ornithine decarboxylase. Translation of ornithine decarboxylase mRNA, but not overall protein biosynthesis is slowed by increased polyamine levels.

Regulation by polyamines of ornithine decarboxylase activity and cell division in the unicellular green alga Chlamydomonas reinhardtii.

Polyamines are required for cell growth and cell division in eukaryotic and prokaryotic organisms. In the unicellular green alga Chlamydomonas reinhardtii, biosynthesis of the commonly occurring polyamines (putrescine, spermidine, and spermine) is dependent on the activity of ornithine decarboxylase (ODC, EC 4.1.1.17) catalyzing the formation of putrescine, which is the precursor of the other two polyamines. In synchronized C. reinhardtii cultures, transition to the cell division phase was preceded by a 4-fold increase in ODC activity and a 10- and a 20-fold increase, respectively, in the putrescine and spermidine levels. Spermine, however, could not be detected in C. reinhardtii cells. Exogenous polyamines caused a decrease in ODC activity. Addition of spermine, but not of spermidine or putrescine, abolished the transition to the cell division phase when applied 7 to 8 h after beginning of the light (growth) phase. Most of the cells had already doubled their cell mass after this growth period. The spermine-induced cell cycle arrest could be overcome by subsequent addition of spermidine or putrescine. The conclusion that spermine affects cell division via a decreased spermidine level was corroborated by the findings that spermine caused a decrease in the putrescine and spermidine levels and that cell divisions also could be prevented by inhibitors of S-adenosyl-methionine decarboxylase and spermidine synthase, respectively, added 8 h after beginning of the growth period. Because protein synthesis was not decreased by addition of spermine under our experimental conditions, we conclude that spermidine affects the transition to the cell division phase directly rather than via protein biosynthesis.