Treatment with granulocyte colony-stimulating factor for mobilization of bone marrow cells in patients with acute myocardial infarction

Nitric Oxide and Hydrogen Sulfide Regulation of Ischemic Vascular Growth and Remodeling

Ischemic vascular remodeling occurs in response to stenosis or arterial occlusion leading to a change in blood flow and tissue perfusion. Altered blood flow elicits a cascade of molecular and cellular physiological responses leading to vascular remodeling of the macro- and micro-circulation. Although cellular mechanisms of vascular remodeling such as arteriogenesis and angiogenesis have been studied, therapeutic approaches in these areas have had limited success due to the complexity and heterogeneous constellation of molecular signaling events regulating these processes. Understanding central molecular players of vascular remodeling should lead to a deeper understanding of this response and aid in the development of novel therapeutic strategies. Hydrogen sulfide (H₂ S) and nitric oxide (NO) are gaseous signaling molecules that are critically involved in regulating fundamental biochemical and molecular responses necessary for vascular growth and remodeling. This review examines how NO and H₂ S regulate pathophysiological mechanisms of angiogenesis and arteriogenesis, along with important chemical and experimental considerations revealed thus far. The importance of NO and H₂ S bioavailability, their synthesis enzymes and cofactors, and genetic variations associated with cardiovascular risk factors suggest that they serve as pivotal regulators of vascular remodeling responses. © 2019 American Physiological Society. Compr Physiol 9:1213-1247, 2019.

G-CSF for Extensive STEMI

RATIONALE

In the exploratory Phase II STEM-AMI (Stem Cells Mobilization in Acute Myocardial Infarction) trial, we reported that early administration of G-CSF (granulocyte colony-stimulating factor), in patients with anterior ST-segment-elevation myocardial infarction and left ventricular (LV) dysfunction after successful percutaneous coronary intervention, had the potential to significantly attenuate LV adverse remodeling in the long-term.

OBJECTIVE

The STEM-AMI OUTCOME CMR (Stem Cells Mobilization in Acute Myocardial Infarction Outcome Cardiac Magnetic Resonance) Substudy was adequately powered to evaluate, in a population showing LV ejection fraction ≤45% after percutaneous coronary intervention for extensive ST-segment-elevation myocardial infarction, the effects of early administration of G-CSF in terms of LV remodeling and function, infarct size assessed by late gadolinium enhancement, and myocardial strain.

METHODS AND RESULTS

Within the Italian, multicenter, prospective, randomized, Phase III STEM-AMI OUTCOME trial, 161 ST-segment-elevation myocardial infarction patients were enrolled in the CMR Substudy and assigned to standard of care (SOC) plus G-CSF or SOC alone. In 119 patients (61 G-CSF and 58 SOC, respectively), CMR was available at baseline and 6-month follow-up. Paired imaging data were independently analyzed by 2 blinded experts in a core CMR lab. The 2 groups were similar for clinical characteristics, cardiovascular risk factors, and pharmacological treatment, except for a trend towards a larger infarct size and longer symptom-to-balloon time in G-CSF patients. ANCOVA showed that the improvement of LV ejection fraction from baseline to 6 months was 5.1% higher in G-CSF patients versus SOC (P=0.01); concurrently, there was a significant between-group difference of 6.7 mL/m² in the change of indexed LV end-systolic volume in favor of G-CSF group (P=0.02). Indexed late gadolinium enhancement significantly decreased in G-CSF group only (P=0.04). Moreover, over time improvement of global longitudinal strain was 2.4% higher in G-CSF patients versus SOC (P=0.04). Global circumferential strain significantly improved in G-CSF group only (P=0.006).

CONCLUSIONS

Early administration of G-CSF exerted a beneficial effect on top of SOC in patients with LV dysfunction after extensive ST-segment-elevation myocardial infarction in terms of global systolic function, adverse remodeling, scar size, and myocardial strain.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT01969890.

Post-MI treatment with G-CSF and EPO-liposome with SLX repairs infarcted myocardium through EPCs mobilization and activation of prosurvival signals in rabbits

We investigated whether combination therapy of G-CSF and erythropoietin (EPO)-liposome with Siaryl Lewis X (SLX) is more cardioprotective than G-CSF or EPO-liposome with SLX alone. For the purpose of generating myocardial infarction (MI), rabbits underwent 30 minutes of coronary occlusion and 14 days of reperfusion. We administered saline (control group, i.v.,), G-CSF (G group, 10 μg/kg/day × 5 days, i.c., starting at 24 hours after reperfusion), EPO-liposome with SLX (LE group, i.v., 2500 IU/kg EPO containing liposome with SLX, immediately after reperfusion), and G-CSF + EPO-liposome with SLX (LE + G group) to the rabbits. The MI size was the smallest in the LE+G group (14.7 ± 0.8%), and smaller in the G group (22.4 ± 1.5%) and LE group (18.5 ± 1.1%) than in the control group (27.8 ± 1.5%). Compared with the control group, the cardiac function and remodeling of the G, LE, and LE + G groups were improved, and LE + G group tended to show the best improvement. The number of CD31-positive microvessels was the greatest in the LE + G group, greater in the G and LE groups than in the control group. Higher expressions of phosphorylated (p)-Akt and p-ERK were observed in the ischemic area of the LE and LE + G groups. The number of CD34+/CXCR4+ cells was significantly higher in the G and LE + G groups. The cardiac SDF-1 was more expressed in the G and LE + G groups. In conclusion, Post-MI combination therapy with G-CSF and EPO-liposome with SLX is more cardioprotective than G-CSF or EPO-liposome with SLX alone through EPCs mobilization, neovascularization, and activation of prosurvival signals.

Acute Myocardial Infarction, Cardioprotection, and Muse Cells

Acute myocardial infarction (AMI) is a common cause of morbidity and mortality worldwide. Severe MI leads to heart failure due to a marked loss of functional cardiomyocytes. First-line treatment for AMI is to reperfuse the occluded coronary artery by PCI as soon as possible. Besides PCI, there are several therapies to reduce the infarct size and improve the cardiac function and remodeling. These are drug therapies such as pharmacological pre- and postconditioning, cytokine therapies, and stem cell therapies. None of these therapies have been clinically developed as a standard treatment for AMI. Among many cell sources for stem cell therapies, the Muse cell is an endogenous non-tumorigenic pluripotent stem cell, which is able to differentiate into cells of all three germ layers from a single cell, suggesting that the Muse cell is a potential cell source for regenerative medicine. Endogenous Muse cell dynamics in the acute phase plays an important role in the prognosis of AMI patients; AMI patients with a higher number of Muse cells in the peripheral blood in the acute phase show more favorable improvement of the cardiac function and remodeling in the chronic phase, suggesting their innate reparative function for the heart. Intravenously administered exogenous Muse cells engrafted preferentially and efficiently to infarct border areas via the S1P-S1PR2 axis and differentiated spontaneously into working cardiomyocytes and vessels, showed paracrine effects, markedly reduced the myocardial infarct size, and delivered long-lasting improvement of the cardiac function and remodeling for 6 months. These findings suggest that Muse cells are reparative stem cells, and thus their clinical application is warranted.

Strategy to Prime the Host and Cells to Augment Therapeutic Efficacy of Progenitor Cells for Patients with Myocardial Infarction

Cell therapy in myocardial infarction (MI) is an innovative strategy that is regarded as a rescue therapy to repair the damaged myocardium and to promote neovascularization for the ischemic border zone. Among several stem cell sources for this purpose, autologous progenitors from bone marrow or peripheral blood would be the most feasible and safest cell-source. Despite the theoretical benefit of cell therapy, this method is not widely adopted in the actual clinical practice due to its low therapeutic efficacy. Various methods have been used to augment the efficacy of cell therapy in MI, such as using different source of progenitors, genetic manipulation of cells, or priming of the cells or hosts (patients) with agents. Among these methods, the strategy to augment the therapeutic efficacy of the autologous peripheral blood mononuclear cells (PBMCs) by priming agents may be the most feasible and the safest method that can be applied directly to the clinic. In this review, we will discuss the current status and future directions of priming PBMCs or patients, as for cell therapy of MI.

Randomized, double-blind, phase I/II study of intravenous allogeneic mesenchymal stromal cells in acute myocardial infarction

BACKGROUND AIMS

Cell therapy is promising as an exploratory cardiovascular therapy. We have recently developed an investigational new drug named Stempeucel (bone marrow-derived allogeneic mesenchymal stromal cells) for patients with acute myocardial infarction (AMI) with ST-segment elevation. A phase I/II randomized, double-blind, single-dose study was conducted to assess the safety and efficacy of intravenous administration of Stempeucel versus placebo (multiple electrolytes injection).

METHODS

Twenty patients who had undergone percutaneous coronary intervention for AMI were randomly assigned (1:1) to receive intravenous Stempeucel or placebo and were followed for 2 years.

RESULTS

The number of treatment-emergent adverse events observed were 18 and 21 in the Stempeucel and placebo groups, respectively. None of the adverse events were related to Stempeucel according to the investigators and independent data safety monitoring board. There was no serious adverse event in the Stempeucel group and there were three serious adverse events in the placebo group, of which one had a fatal outcome. Ejection fraction determined by use of echocardiography showed improvement in both Stempeucel (43.06% to 47.80%) and placebo (43.44% to 45.33%) groups at 6 months (P = 0.26). Perfusion scores measured by use of single-photon emission tomography and infarct volume measured by use of magnetic resonance imaging showed no significant differences between the two groups at 6 months.

CONCLUSIONS

This study showed that Stempeucel was safe and well tolerated when administered intravenously in AMI patients 2 days after percutaneous coronary intervention. The optimal dose and route of administration needs further evaluation in larger clinical trials (http://clinicaltrials.gov/show/NCT00883727).

Granulocyte colony stimulating factor therapy for acute myocardial infarction

BACKGROUND

Acute myocardial infarction (AMI) is the leading cause of death in developed countries, and current treatment modalities have failed to regenerate the dead myocardium resulting from the ischemic damage. Stem cells have the potential to regenerate the damaged myocardium. These cells can be mobilized from the bone marrow by factors such as granulocyte colony stimulating factor (G-CSF).

OBJECTIVES

To assess the effects of stem cell mobilization following granulocyte colony stimulating factor therapy in patients with acute myocardial infarction.

SEARCH METHODS

We searched CENTRAL (The Cochrane Library Issue 4, 2010), MEDLINE (1950 to November week 3, 2010), EMBASE (1980 to 2010 week 48), BIOSIS Previews (1969 to 30 November 2010), ISI Science Citation Index Expanded (1970 to 4 December 2010) and ISI Conference Proceedings Citation Index - Science (1990 to 4 December 2010). We also checked reference lists of articles.

SELECTION CRITERIA

We included randomized controlled trials including participants with a clinical diagnosis of AMI who were randomly allocated to the subcutaneous administration of G-CSF through a daily dose of 2.5, 5 or 10 microgram/kg for four to six days or placebo. No age or other restrictions were applied for the selection of patients.

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials, assessed trials for eligibility and methodological quality, and extracted data regarding the clinical efficacy and adverse outcomes. Disagreements were resolved by the third author.

MAIN RESULTS

We included seven trials reported in 30 references in the review (354 participants). In all trials, G-CSF was compared with placebo preparations. Dosage of G-CSF varied among studies, ranging from 2.5 to 10 microgram/kg/day. Regarding overall risk of bias, data regarding the generation of randomization sequence and incomplete outcome data were at a low risk of bias; however, data regarding binding of personnel were not conclusive. The rate of mortality was not different between the two groups (RR 0.64, 95% CI 0.15 to 2.80, P = 0.55). Regarding safety, the limited amount of evidence is inadequate to reach any conclusions regarding the safety of G-CSF therapy. Moreover, the results did not show any beneficial effects of G-CSF in patients with AMI regarding left ventricular function parameters, including left ventricular ejection fraction (RR 3.41, 95% CI -0.61 to 7.44, P = 0.1), end systolic volume (RR -1.35, 95% CI -4.68 to 1.99, P = 0.43) and end diastolic volume (RR -4.08, 95% CI -8.28 to 0.12, P = 0.06). It should also be noted that the study was limited since the trials included lacked long enough follow up durations.

AUTHORS' CONCLUSIONS

Limited evidence from small trials suggested a lack of benefit of G-CSF therapy in patients with AMI. Since data of the risk of bias regarding blinding of personnel were not conclusive, larger RCTs with appropriate power calculations and longer follow up durations are required in order to address current uncertainties regarding the clinical efficacy and therapy-related adverse events of G-CSF treatment.

Clinical outcome after stem cell mobilization with granulocyte-colony-stimulating factor after acute ST-elevation myocardial infarction: 5-year results of the STEMMI trial

BACKGROUND

Granulocyte-colony-stimulating factor (G-CSF) has been investigated in trials aiming to promote recovery of myocardial function after myocardial infarction. Long-term safety-data have never been reported. A few studies indicated an increased risk of in-stent re-stenosis. We aimed to investigate clinical events 5 years after inclusion into a randomized trial of G-CSF versus placebo.

METHODS

Seventy-eight patients were randomized, from 2003-2005, to G-CSF or placebo after myocardial infarction. Four patients withdrew consent prior to study treatment and were excluded leaving 36 and 38 in the placebo- and G-CSF groups. Information about all hospital admittances of included patients until 2010 was extracted from a national register. The only censoring event was immigration. The events were combined into four prespecified endpoints: Time to (1) first hospital admittance (all cause), (2) first cardiovascular-related hospital admittance, (3) first major cardiovascular event, and (4) death.

RESULTS

One patient (1%) was lost to follow-up. Four patients (4%) died in the follow-up period, three in the G-CSF group and one in the placebo group (p = 0.4). Hazard ratio for all cause hospital admittance was 0.7 (95% CI 0.38-1.29). The incidence of both new myocardial infarction (p = 1.0) and revascularization procedures (p = 0.4) were similar in the two groups. Survival analyses showed no differences in the occurrence of any of the four prespecified composite endpoints between the two groups (p = 0.6; 0.5; 0.8; 0.3).

CONCLUSIONS

We found no indication of increased risk of adverse events up to 5 years after G-CSF treatment. These results support the continued investigation of G-CSF for cardiac therapy.

Double gene therapy with granulocyte colony-stimulating factor and vascular endothelial growth factor acts synergistically to improve nerve regeneration and functional outcome after sciatic nerve injury in mice

Peripheral-nerve injuries are a common clinical problem and often result in long-term functional deficits. Reconstruction of peripheral-nerve defects is currently undertaken with nerve autografts. However, there is a limited availability of nerves that can be sacrificed and the functional recovery is never 100% satisfactory. We have previously shown that gene therapy with vascular endothelial growth factor (VEGF) significantly improved nerve regeneration, neuronal survival, and muscle activity. Our hypothesis is that granulocyte colony-stimulating factor (G-CSF) synergizes with VEGF to improve the functional outcome after sciatic nerve transection. The left sciatic nerves and the adjacent muscle groups of adult mice were exposed, and 50 or 100 μg (in 50 μl PBS) of VEGF and/or G-CSF genes was injected locally, just below the sciatic nerve, and transferred by electroporation. The sciatic nerves were transected and placed in an empty polycaprolactone (PCL) nerve guide, leaving a 3-mm gap to challenge nerve regeneration. After 6 weeks, the mice were perfused and the sciatic nerve, the dorsal root ganglion (DRG), the spinal cord and the gastrocnemius muscle were processed for light and transmission electron microscopy. Treated animals showed significant improvement in functional and histological analyses compared with the control group. However, the best results were obtained with the G-CSF+VEGF-treated animals: quantitative analysis of regenerated nerves showed a significant increase in the number of myelinated fibers and blood vessels, and the number of neurons in the DRG and motoneurons in the spinal cord was significantly higher. Motor function also showed that functional recovery occurred earlier in animals receiving G-CSF+VEGF-treatment. The gastrocnemius muscle showed an increase in weight and in the levels of creatine phosphokinase, suggesting an improvement of reinnervation and muscle activity. These results suggest that these two factors acted synergistically and optimized the nerve repair potential, improving regeneration after a transection lesion.

Bone marrow-derived cells contribute to cell turnover in aging murine hearts

The paradigm that cardiac myocytes are non-proliferating, terminally differentiated cells was recently challenged by studies reporting the ability of bone marrow-derived cells (BMCs) to differentiate into cardiomyocytes after myocardial damage. However, little knowledge exists about the role of BMCs in the heart during physiological aging. Twelve-week-old mice (n=36) were sublethally irradiated and bone marrow from littermates transgenic for enhanced green fluorescent protein (eGFP) was transplanted. After 4 weeks, 18 mice were sacrificed at the age of 4 months and served as controls (group A); the remaining mice were sacrificed at the age of 18 months (group B). Group A did not exhibit a significant number of eGFP+ cells, whereas 9.4±2.8 eGFP+ cells/mm2 was documented in group B. In total, only five eGFP+ cardiomyocytes were detected in 20 examined hearts, excluding a functional role of BM differentiation in cardiomyocytes. Similarly, a relevant differentiation of BMCs in endothelial or smooth muscle cells was excluded. In contrast, numerous BM-derived fibroblasts and myofibroblasts were observed in group B, but none were detected in group  A. The present study demonstrates that BMCs transdifferentiate into fibroblasts and myofibroblasts in the aging murine myocardium, suggesting their contribution to the preservation of the structural integrity of the myocardium, while they do not account for regenerative processes of the heart.

Hematopoietic cytokines for cardiac repair: mobilization of bone marrow cells and beyond

Hematopoietic cytokines, traditionally known to influence cellular proliferation, differentiation, maturation, and lineage commitment in the bone marrow, include granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor, stem cell factor, Flt-3 ligand, and erythropoietin among others. Emerging evidence suggests that these cytokines also exert multifarious biological effects on diverse nonhematopoietic organs and tissues. Although the precise mechanisms remain unclear, numerous studies in animal models of myocardial infarction (MI) and heart failure indicate that hematopoietic cytokines confer potent cardiovascular benefits, possibly through mobilization and subsequent homing of bone marrow-derived cells into the infarcted heart with consequent induction of myocardial repair involving multifarious mechanisms. In addition, these cytokines are also known to exert direct cytoprotective effects. However, results from small-scale clinical trials of G-CSF therapy as a single agent after acute MI have been discordant and largely disappointing. It is likely that cardiac repair following cytokine therapy depends on a number of known and unknown variables, and further experimental and clinical studies are certainly warranted to accurately determine the true therapeutic potential of such therapy. In this review, we discuss the biological features of several key hematopoietic cytokines and present the basic and clinical evidence pertaining to cardiac repair with hematopoietic cytokine therapy.

Myocardial remodeling: cellular and extracellular events and targets

The focus of this review is on translational studies utilizing large-animal models and clinical studies that provide fundamental insight into cellular and extracellular pathways contributing to post-myocardial infarction (MI) left ventricle (LV) remodeling. Specifically, both large-animal and clinical studies have examined the potential role of endogenous and exogenous stem cells to alter the course of LV remodeling. Interestingly, there have been alterations in LV remodeling with stem cell treatment despite a lack of long-term cell engraftment. The translation of the full potential of stem cell treatments to clinical studies has yet to be realized. The modulation of proteolytic pathways that contribute to the post-MI remodeling process has also been examined. On the basis of recent large-animal studies, there appears to be a relationship between stem cell treatment post-MI and the modification of proteolytic pathways, generating the hypothesis that stem cells leave an echo effect that moderates LV remodeling.

Administration of granulocyte colony-stimulating factor ameliorates radiation-induced hepatic fibrosis in mice

On the basis of the recent report that granulocyte colony-stimulating factor (G-CSF) treatment significantly improves survival and liver histology among chemically injured mice, we investigated whether G-CSF administration could contribute to faster recovery and promote tissue repair after local liver irradiation. Bone marrow chimeric female C57BL/6 mice were treated with G-CSF at days 7, 14, and 21 after local liver irradiation. We assessed the fibrosis index and the origin of proliferating cells reconstituting the liver at 2 or 5 weeks after radiation challenge. At day 35 after local irradiation, we observed G-CSF treatment to significantly reduce radiation-induced liver damage and collagen deposition. In addition, hepatic hydroxyproline levels and serum fibrosis markers in mice receiving G-CSF administration after radiation challenge were significantly lower compared with those of control mice. More importantly, histological examination suggested that recovery from hepatic damage was much better among the G-CSF-treated mice. Immunofluorescence and fluorescence in situ hybridization analyses revealed that donor cells engrafted into the host liver displayed epithelium-like morphology and expressed albumin, albeit at low frequency. These results suggested that G-CSF treatment initiated endogenous hepatic tissue regeneration in response to radiation injury and ameliorated its fibrogenic effects.

Rebuilding the damaged heart: the potential of cytokines and growth factors in the treatment of ischemic heart disease

Cytokine therapy promises to provide a noninvasive treatment option for ischemic heart disease. Cytokines are thought to influence angiogenesis directly via effects on endothelial cells or indirectly through progenitor cell-based mechanisms or by activating the expression of other angiogenic agents. Several cytokines mobilize progenitor cells from the bone marrow or are involved in the homing of mobilized cells to ischemic tissue. The recruited cells contribute to myocardial regeneration both as a structural component of the regenerating tissue and by secreting angiogenic or antiapoptotic factors, including cytokines. To date, randomized, controlled clinical trials have not reproduced the efficacy observed in pre-clinical and small-scale clinical investigations. Nevertheless, the list of promising cytokines continues to grow, and combinations of cytokines, with or without concurrent progenitor cell therapy, warrant further investigation.

Human CD34+ cells mobilized by granulocyte colony-stimulating factor ameliorate radiation-induced liver damage in mice

Introduction

On the basis of the recently recognized potential of hematopoietic stem cells (HSCs) to give rise to hepatocytes, we have assessed the potential of granulocyte colony-stimulating factor (G-CSF)-mobilized bone marrow-derived CD34⁺ HSCs to contribute to faster recovery and promote regeneration process after acute liver injury by radiation.

Methods

G-CSF-mobilized CD34⁺ HSCs (1 × 10⁵ cells per mouse) were injected via tail vein in the irradiated femal nonobese diabetic/severe combined immunodeficient mice. Irradiated control animals received only saline infusion.

Results

The mobilized CD34⁺ HSCs significantly ameliorated radiation-induced liver damage. In the liver of recipient mice killed 21 days after irradiation, human albumin⁺ Y-chromosome⁺ hepatocyte-like cells, or human cytokeratin⁺ Y-chromosome⁺ hepatocyte-like cells formed cords of hepatocytes, occupied ~30% of the 4-μm section surrounding portal tracts. Furthermore, human-specific albumin mRNA expressed in the liver and human albumin was detected in the serum only in the CD34⁺ HSC-treated mice.

Conclusions

Treatment with G-CSF-mobilized CD34⁺ HSCs from bone marrow into peripheral blood could significantly promote tissue reparation after acute liver injury by radiation in mice, possibly by the ability of CD34⁺ HSCs to generate hepatocytes. So mobilization of CD34⁺ HSCs might offer a novel therapeutic approach for the treatment of radiation-induced complications after radiotherapy or other acute liver diseases in humans.

Stem cell therapy in acute myocardial infarction: a review of clinical trials

Stem cells (SCs) possess the ability to differentiate into cells of various tissues. Although the differentiation of SCs into functional cardiomyocytes has been difficult to demonstrate in humans, clinical trials using SCs in the setting of acute myocardial infarction (AMI) have demonstrated variable results. Interpretation of these trials has been difficult because of multiple variables, which include differences in trial design, cell type, timing of cell delivery, and outcome measurements. Herein, a summary of all clinical trials in subgroups of direct injection, indirect mobilization, and combination approaches of SC therapy in AMI is provided with significant findings in each group.

Cytokines and myocardial regeneration: a novel treatment option for acute myocardial infarction

The regenerative capacity of the myocardium and its blood vessels has now been well demonstrated. The cytokines granulocyte colony-stimulating factor, erythropoietin, and stem cell factor may play a role in helping to stimulate cell regeneration under normal physiologic conditions and in patients with myocardial injury. After an ischemic insult, cytokines are released into the peripheral circulation and signal for the mobilization of stem cells. In experimental cardiac injury models, the addition of cytokines has been shown to improve myocardial function with and without the concurrent use of stem cell therapy. Preliminary studies in humans using cytokine therapy alone for treating myocardial infarction have been disappointing. Future studies in patients with myocardial injury need to examine the use of various combinations of cytokines, with and without the addition of intravascular stem cell infusions or direct stem cell injections.

Stem cell mobilisation for myocardial repair

BACKGROUND

The idea that autologous bone marrow derived stem cells (BMCs) can transdifferentiate into cardiomyocytes or vascular cells has been challenged in several scientific reports.

OBJECTIVE/METHODS

This review summarises conditions for stem cell mobilisation, their use for therapeutic approaches to prevent ischaemic cardiomyopathy after acute myocardial infarction and current clinical trials. Mechanisms for mobilisation and homing of BMCs are discussed.

RESULTS/CONCLUSIONS

The improvement in cardiac function after migration of autologous BMCs to the heart can be explained by their paracrine effects, inducing angiogenesis and preventing ischaemic myocardium from apoptosis. These effects may explain why the number of circulating BMCs is directly correlated with cardiovascular risk and life expectancy. Exercise and hormones are physiological stimuli for the mobilisation of BMCs, whereas cardiovascular risk factors severely reduce their number and functions. Current cardiovascular medications increase the amounts of autologous BMCs.

Timing of granulocyte-colony stimulating factor treatment after acute myocardial infarction and recovery of left ventricular function: results from the STEMMI trial

BACKGROUND

Granulocyte-colony stimulating factor (G-CSF) therapy after ST-elevation myocardial infarction (STEMI) have not demonstrated impact on systolic recovery compared to placebo. However, recent studies suggest that timing of G-CSF therapy is crucial.

METHODS

Timing of G-CSF treatment was analyzed in the STEMMI MRI subpopulation including 54 patients with STEMI treated with primary percutaneous coronary intervention (PCI) <12 h after symptom onset. Patients were randomized to double blind treatment with G-CSF (10 microg/kg/day) or placebo. Treatment was initiated from 17 to 65 h (mean 30) after PCI. Left ventricular ejection fraction (LVEF) was evaluated with MRI.

RESULTS

Recovery of LVEF from baseline to 6 months was not associated with time from PCI to G-CSF. An identical improvement in LVEF was found in the placebo group and the G-CSF group (p=0.8). There was no correlation between time from PCI to G-CSF and maximum plasma concentration of CD34+ cells (r=-0.3, p=0.1). Similar results were found from data on recovery of the infarction size and change in the systolic wall thickening.

CONCLUSIONS

In the time window from 17 to 65 h after STEMI treated with PCI, the timing of G-CSF treatment does not seem to affect the recovery of LVEF. It remains to be determined if very early, or very late G-CSF treatment might be effective.

Granulocyte colony-stimulating factor exacerbates cardiac fibrosis after myocardial infarction in a rat model of permanent occlusion

AIMS

Controversy exists regarding the effects of granulocyte colony-stimulating factor (G-CSF) on post-infarction remodelling, which is regulated by matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). The aim of this study was to investigate the impact of G-CSF administration on cardiac MMP/TIMP ratios and long-term remodelling in a rat model of acute myocardial infarction (MI).

METHODS AND RESULTS

Sprague-Dawley rats underwent coronary ligation to produce MI. Rats surviving the MI for 3 h were randomized to receive G-CSF (50 microg/kg/day for 5 consecutive days, n = 16) or saline (n = 10). Sham-operated animals received no treatment (n = 10). G-CSF injection significantly increased circulating white blood cells, neutrophils, and monocytes. Western blotting revealed that the ratios of MMP-2/TIMP-1 and MMP-9/TIMP-1 were significantly decreased in the infarcted myocardium. At 3 months, echocardiographic and haemodynamic examinations showed that the G-CSF treatment induced left ventricular (LV) enlargement and dysfunction. Histological analysis revealed that the extent of myocardial fibrosis and infarct size were larger in the G-CSF group than in the Saline group. Furthermore, G-CSF treated animals showed a significantly lower post-MI survival during the study period.

CONCLUSION

Decrease of cardiac MMP/TIMP ratios by G-CSF after infarction may be important as a mechanism in promotion of myocardial fibrosis, which further facilitates infarct expansion and LV dysfunction.

G-CSF therapy with mobilization of bone marrow stem cells for myocardial recovery after acute myocardial infarction--a relevant treatment?

This review of adjunctive therapy with subcutaneous granulocyte-colony stimulating factor (G-CSF) to patients with acute myocardial infarction (AMI) focus on the cardioprotective effects and potential mechanisms of G-CSF and discuss the therapeutic potential of G-CSF. All clinical trials published in peer-reviewed journals identified through PubMed are discussed. G-CSF treatment seems to be safe, and initial unblinded trials in patients with AMI were encouraging. However, larger double-blind placebo-controlled trials have not been able to demonstrate improved myocardial recovery after G-CSF treatment. Current controversies in interpretation of the results include 1) importance of direct cardiac effect of G-CSF vs indirect through bone marrow stem and progenitor cell mobilization, 2) importance of timing of G-CSF therapy, 3) importance of G-CSF dose, and 4) importance of cell types mobilized from the bone-marrow. Cell-based therapies to improve cardiac function remain promising and further experimental and clinical studies are warranted to determine the future role of G-CSF.

VEGF signaling inhibitors: more pro-apoptotic than anti-angiogenic

The vascular endothelial growth factor (VEGF) family of polypeptide growth factors regulates a family of VEGF receptor (VEGFR) tyrosine kinases with pleiotropic downstream effects. Angiogenesis is the best known of these effects, but additional VEGF-dependent actions include increased vascular permeability, paracrine/autocrine growth factor release, enhancement of cell motility, and inhibition of apoptosis. In theory, therapeutic inhibition of angiogenesis should reduce tumor perfusion and thus increase tumor hypoxia and chemoresistance, but in clinical practice the VEGF antibody bevacizumab acts as a broad-spectrum chemosensitizer. Since VEGFR expression occurs in many tumor types, such chemosensitization is more readily explained by direct inhibition of tumor cell survival signals than by indirect stromal/vascular effects. The emerging model of anti-VEGF drug action being mediated primarily by tumoral (as distinct from endothelial) VEGFRs has clinically important implications for optimizing the anti-metastatic efficacy of this expanding drug class.

A meta-analysis of stem cell mobilization by granulocyte colony-stimulating factor in the treatment of acute myocardial infarction

OBJECTIVE

This project was aimed at evaluating the safety and efficacy of granulocyte colony-stimulating factor (G-CSF) as an adjunctive therapy to the standard therapy [percutaneous coronary interventions (PCI) and conventional medication] after acute myocardial infarction (AMI).

METHODS

A meta-analysis of randomized controlled trials (RCTs) of G-CSF as an adjunctive therapy to standard therapy versus standard therapy was performed. The endpoints were defined as (1) target-vessel restenosis, (2) cumulative cardiac events (CCEs) that were a combined endpoint of all-cause deaths, reinfarction, and target-vessel revascularization, and (3) the changes in left ventricular ejection fraction (LVEF) from baseline to follow-up.

RESULTS

320 patients were involved in 6 RCTs, of whom 160 were randomized to the G-CSF group and 160 to the control group. The follow-up period was 6.17 +/- 3.49 months. There was no significant difference in the risk of target-vessel restenosis (P = 0.90) or CCEs (P = 0.59) between the two groups. When a pooled analysis of the changes in LVEF was performed with fixed-model effect, a significant heterogeneity was observed (P < 0.00001). The pooled analysis was thus conducted with random-model effect and did not show a significant improvement as compared to the control group (P = 0.34). A similar result was found in the sensitivity analysis based on five placebo-controlled trials involving 270 patients (P = 0.94).

CONCLUSIONS

G-CSF as an adjunctive therapy to standard therapy for patients with AMI may be safe. However, there is not much supporting evidence that this treatment could further improve LVEF. Since there are relatively few RCTs that meet the inclusion criteria and are heterogeneous in design, further research is required.

Short- and long-term changes in myocardial function, morphology, edema, and infarct mass after ST-segment elevation myocardial infarction evaluated by serial magnetic resonance imaging

BACKGROUND

Knowledge of the natural course after an ST-elevation myocardial infarction (STEMI) treated according to guidelines is limited because comprehensive serial magnetic resonance imaging (MRI) of systolic left ventricular function, edema, perfusion, and infarct size after STEMI has not been undertaken. The aim of this study was to evaluate effects of therapy for STEMI on left ventricular function and perfusion and to test the hypothesis that myocardial perfusion by MRI predicts recovery of left ventricular function.

METHODS

Cine MRI, edema, first-pass perfusion, and late enhancement imaging were performed in 58 patients at day 2 and at 1 and 6 months after successful primary percutaneous coronary stent intervention for STEMI.

RESULTS

Ejection fraction increased 6.3% during the first month (P < .001) and 1.9% from 1 to 6 months (P < .06), indicating a maximal recovery very early after the infarction. The systolic wall thickening in the infarct area almost doubled (P < .001), the perfusion of infarcted myocardium increased approximately 50% (P = .02), and perfusion improved in 72% of patients. Edema decreased with a mean of 2 segments (P < .001) during the first month and another 2.5 segments from 1 to 6 months (P < .001). Infarct size decreased to 1 month (P = .01) and was unchanged from 1 to 6 months (P = .5). Baseline perfusion did not predict improvement in ejection fraction (r = 0.2, P = .2) but did predict regional systolic function (P = .03).

CONCLUSIONS

Left ventricular function, perfusion, and infarct mass recovered substantially after STEMI, with the main part of the change within the first month. First-pass perfusion at rest appeared to predict regional ventricular recovery.

G-CSF therapy for acute myocardial infarction

Granulocyte-colony-stimulating factor (G-CSF) has recently been shown to have various effects besides promoting the proliferation and differentiation of myeloid progenitor cells, including the mobilization of bone marrow stem cells and the regeneration infarcted hearts in mice. Recent animal studies have also revealed that G-CSF activates multiple signaling pathways, such as Akt and also the Janus family kinase-2 and signal transducer and activation of transcription-3 (Jak2-STAT3) pathway, in cardiac myocytes. It prevents left ventricular remodeling after myocardial infarction by decreasing cardiomyocyte death and by increasing the number of blood vessels, suggesting the importance of direct actions of G-CSF on the myocardium rather than through mobilization and differentiation of stem cells. Several clinical trials have been performed to study the efficacy of G-CSF therapy in patients with acute myocardial infarction but the results remain controversial because the protocols followed varied between the trials.

STEM CELL MECHANISMS AND PARACRINE EFFECTS

Heart disease remains the leading cause of death in the industrialized world. Stem cell therapy is a promising treatment modality for injured cardiac tissue. A novel mechanism for this cardioprotection may include paracrine actions. Cardiac surgery represents the unique situation where preischemia and postischemia treatment modalities exist that may use stem cell paracrine protection. This review (1) recalls the history of stem cells in cardiac disease and the unraveling of its mechanistic basis for protection, (2) outlines the pathways for stem cell-mediated paracrine protection, (3) highlights the signaling factors expressed, (4) explores the potential of using stem cells clinically in cardiac surgery, and (5) summarizes all human stem cell studies in cardiac disease to date.

Drugs, gene transfer, signaling factors: a bench to bedside approach to myocardial stem cell therapy

In the past few years, the dogma that the heart is a terminally differentiated organ has been challenged. Evidence from preclinical investigations emerged that there are cells, even in the heart itself, that may be able to restore impaired cardiac function after myocardial infarction. Although the exact mechanisms by which the infarcted heart can be repaired by stem cells are not yet fully defined, there is a new optimism among cardiologists that this treatment will prove successful in addressing the cause of heart failure after myocardial infarction-myocyte loss. Despite the promising preliminary data of human myocardial stem cell trials, scientists have also focused on the possibility of enhancing the underlying mechanisms of stem cell repair to gain healthier myocardial tissue. Attempts to induce neo-angiogenesis by transfecting stem cells with signaling factors (such as VEGF), to raise the number of endothelial progenitor cells with medical treatments (such as statins), to transfect stem cells with heat shock protein 70 (as a cardioprotective agent against ischemia) and to enhance the healing process after myocardial infarction with the use of various forms of stimulating factors (G-CSF, SCF, GM-CSF) have been made with notable results. In this article, we summarize the evidence from preclinical and clinical myocardial stem cell studies that have addressed the possibility of enhancing the regenerative capacity of cells used after myocardial infarction.

Endothelial progenitor cells as therapeutic vectors in cardiovascular disorders: from experimental models to human trials

Cell-based therapy approaches for the restoration of blood flow in ischemic organs has recently received growing interest. A considerable number of reports have documented the presence of circulating, bone marrow-derived endothelial progenitor cells (EPC) in adult peripheral blood. These putative cells are thought to participate in postnatal growth of new blood vessels. Mounting evidence from animal studies point to potential therapeutic applications of EPCs in the treatment of a wide range of cardiovascular (CV) disorders, while preliminary results from the pilot clinical trials still remain equivocal. Here, we review the experimental data that has accumulated so far from animal and clinical studies regarding the potential importance of EPCs. In addition, we discuss the potential hurdles as well as future options of EPC-based therapy.

New targets for established proteins: exploring G-CSF for the treatment of stroke

Several recent reports describe the efficacy of the hematopoietic factor granulocyte-colony-stimulating factor (G-CSF) in models of stroke and neurodegeneration. Here, we discuss the role of G-CSF as a novel type of multifactorial drug with which to treat stroke, and describe aspects of its modes of action in stroke, in addition to the relationship between clinical trials and the preclinical dataset. Neuroprotective activity in stroke models seems to be based on a direct anti-apoptotic activity in neurons that is mediated by the neuronally expressed G-CSF receptor. Explanations for the long-term effects that improve recovery in different experimental models of stroke include the enhancement of neurogenesis in the adult brain and the stimulation of blood vessel formation. Additional beneficial effects might be based on systemic influences on immunocompetence and inflammation parameters, and the activation of bone-marrow-derived stem cells. Several clinical trials have been initiated in stroke patients, mainly to demonstrate the safety of G-CSF in this setting.

The expanding role of left ventricular functional assessment using gated myocardial perfusion SPECT: the supporting actor is stealing the scene

BACKGROUND

Gating of single-photon emission computed tomography (SPECT) has significantly improved the reliability and diagnostic accuracy of myocardial perfusion imaging. The functional parameters derived from this technique, mainly left ventricular volumes and ejection fraction, have been demonstrated to be accurate and reproducible. They are able to increase the detection of severe and extensive coronary artery disease and show a significant incremental prognostic power over perfusion abnormalities. Therefore, the importance given to gated SPECT functional data has progressively grown.

DISCUSSION

This circumstance has further expanded the indications for myocardial perfusion imaging and strengthened its position among the different imaging modalities. Moreover, several studies show that the evaluation of ventricular function may have a leading part in justifying the execution of perfusion scintigraphy in various clinical conditions.

AIM

Aim of this review is to describe this evolution of gated SPECT functional assessment from a supporting rank with respect to perfusion, to a main actor position in the field of cardiac imaging.

The effect of granulocyte colony stimulating factor on regional and global myocardial function in the porcine infarct model

BACKGROUND

Stem cell therapy has been shown to attenuate the reduction of left ventricular function following myocardial infarction. Most studies have utilized either a direct injection or intra-coronary infusion of cells, but cytokine mobilization of stem cells in the murine model of acute myocardial infarction has been reported to induce similar improvement in cardiac function.

METHODS

An antero-apical infarction was induced in swine by balloon occlusion, followed by the daily administration of granulocyte colony stimulating factor (G-CSF) or placebo for 5 days. We used left ventricular angiograms and 2D echocardiograms to assess global function, and 3D echocardiograms to assess regional function prior to infarction, immediately following infarction, and at 8 weeks. Histologic evaluation was performed after sacrifice at 8 weeks.

RESULTS

There was no significant difference in early or late post-infarction left ventricular ejection fraction or in myocardial histology between the two groups. Following G-CSF therapy, however, 3D echocardiography demonstrated that the regional ejection fractions of the infarcted segments showed a 50.3% improvement in the G-CSF pigs compared to a 7.4% deterioration in the untreated pigs (p=0.005).

CONCLUSIONS

Global left ventricular ejection fraction remained unchanged, and there is no histologic evidence for infarct attenuation following G-CSF infusion in the porcine infarct-reperfusion model. There was recovery of regional function in the infarcted segment in the G-CSF pigs. These data suggest that bone marrow mobilization in larger species has limited potential as a therapy designed to replace infarcted myocardium or to improve overall cardiac function, although further studies are needed to examine regional effect in the infarct area.

Granulocyte-colony-stimulating factor in acute myocardial infarction: future perspectives after FIRSTLINE-AMI and REVIVAL-2

Granulocyte-colony-stimulating factor (G-CSF) seems to have direct cardioprotective effects related to mobilization of autologous bone-marrow mononuclear CD34(+) cells. These properties have attracted the attention of researchers investigating new therapeutic strategies for acute myocardial infarction. The role of G-CSF in bone-marrow cell mobilization removes the need for bone-marrow aspiration and repeated invasive procedures. This factor, coupled with the fact that G-CSF can be administered by noninvasive subcutaneous injection, give this approach a potential advantage over other cell-therapy options. This article is intended to present a concise overview of the current experimental and clinical findings for G-CSF therapy after acute myocardial infarction. In particular, we discuss the conflicting findings from the front-integrated revascularization and stem cell liberation in evolving acute myocardial infarction (FIRSTLINE-AMI) and the Regenerate Vital Myocardium by Vigorous Activation of Bone Marrow Stem Cells (REVIVAL-2) studies.

G-CSF and HGF: combination of vasculogenesis and angiogenesis synergistically improves recovery in murine hind limb ischemia

Granulocyte colony-stimulating factor (G-CSF) is known to mobilize bone marrow stem cells into the peripheral circulation. This study was designed to investigate whether G-CSF by itself or in combination with hepatocyte growth factor (HGF) can promote vasculogenesis and angiogenesis in murine hind limb ischemia. Hind limb ischemia was induced in BALB/c nude or C57/BL6 mice that received bone marrow transplantation from green fluorescent protein (GFP)-transgenic mice. In the HGF group, hHGF expression plasmid was injected into the ischemic muscles. In the G-CSF group, G-CSF was administered subcutaneously for 10 days. The G-CSF+HGF group was concomitantly treated with G-CSF and HGF, and the control group received no treatment. All effects were confirmed at 4 weeks. The G-CSF+HGF group had a higher laser Doppler blood perfusion index, higher microvessel density, and a lower incidence of hind limb necrosis than the other groups. Confocal laser microscopy revealed that a number of GFP-positive cells infiltrated to the vasculature of the ischemic area. Some of the GFP positive cells were clearly co-immunostained with alpha-smooth muscle actin as well as von Willebrand factor. G-CSF-mobilized stem cells co-expressed CD49d and CD34, which would have promoted their adhesion to cells in the ischemic muscle that expressed HGF-induced vascular cell adhesion molecule-1. The combination of G-CSF and HGF had a significant synergistic effect, suggesting that the combination of mobilization of stem cells from bone marrow to peripheral circulation and their recruitment to the ischemic area might potentiate angiogenesis and vasculogenesis.

Present and future of stem cells for cardiovascular therapy

In this review we summarize the available evidence regarding the application of stem cell therapy for human cardiovascular repair, going over the principal concepts that will help us understand the present and future of this therapy: first the different types of cells available in clinical practice, second the delivery approaches, and third highlighting the most important clinical studies and their efficacy and safety results. In addition, we also speculate on the value of current clinical data to gain an insight into the mechanism of stem cell-based cardiac repair and to design clinical trials in the future.

Cardiac repair--fact or fancy?

Patients with ischemic cardiomyopathy have a poor prognosis despite all pharmacological, interventional and surgical treatment modalities currently applied. Heart transplantation remains the ideal treatment for this group of patients but the scarcity of donors hinders its widespread application. The autologous transplantation of stem cells (SCs) for cardiac repair is emerging as a new therapy for patients with myocardial dysfunction early after an acute infarction or ischemic cardiomyopathy. The rationale of this novel method is the enhancement of the repair mechanisms achieved by tissue-specific and circulating stem/progenitor cells. SCs assist naturally occurring myocardial repair by contributing to increased myocardial perfusion and contractile performance especially in the setting of acute myocardial infarction (AMI), but also in patients with chronic ischemic heart failure and advanced, diffuse coronary artery disease. The exact mechanism of their action has not been fully elucidated. Few studies continue to suggest a formation of few new contractile tissue. The majority if investigators believe that these cells do not persist long in the myocardium but that they secrete vascular growth and other cardioprotective factors.

Actions and therapeutic potential of G-CSF and GM-CSF in cardiovascular disease

Despite their names, the cytokines granulocyte- and granulocyte-macrophage-colony stimulating factor (G-CSF and GM-CSF respectively) have actions far beyond simply stimulating the proliferation of neutrophil and monocyte lineage cells. A comprehensive body of evidence now exists demonstrating that G-CSF and GM-CSF effectively mobilize bone-marrow-derived progenitor cells into the peripheral circulation. These mobilized progenitor cells can be conveniently harvested for use in reconstituting bone marrow by transplantation after myelo-ablative treatment of hematological malignancies. In addition, much evidence has recently emerged to suggest that these cytokines may have multiple direct and indirect beneficial cardiovascular effects--including neovascularization of ischemic myocardium and reducing the extent of myocardial damage after infarction. Based on this knowledge and a strong safety record in hematological applications, a number of early clinical trials have evaluated the use of G-CSF or GM-CSF in patients with both acute and chronic myocardial ischemia. Although the interpretation of these trials is complicated by heterogeneity in study design, small patient numbers and methodological concerns related to appropriate selection and blinding of patients, the results of ongoing larger phase II/III trials should soon be available to determine if these agents will be useful additions to the cardiovascular armamentarium.

Cell-based therapies after myocardial injury

Recent translational research into the emerging field of cardiac cell therapy has paved the way for novel clinical treatment strategies. However, neither the ideal source and type of cell nor the critical quantity and mode of application have yet been defined. In patients who have undergone acute myocardial infarction, several cell-based approaches are currently being evaluated, such as intracoronary delivery of autologous mononuclear bone marrow cells or enriched hematopoietic progenitor cell products; systemic cytokine stimulation with release of bone marrow progenitor cells into the systemic circulation; and both intravenous and intracoronary delivery of allogenic marrow stroma cell-derived cells. There are potentially encouraging data for each of these strategies, based to date on small cohorts with conflicting or equivocal recovery of function. Taken together, it is too early to consider cell therapy for heart disease to be effective. Future setbacks are likely, but both clinicians and basic scientists will eventually introduce more potent cell-based strategies into the clinical arena.

Beraprost sodium enhances neovascularization in ischemic myocardium by mobilizing bone marrow cells in rats

Beraprost sodium, an orally active prostacyclin analogue, has vasoprotective effects such as vasodilation and antiplatelet activities. We investigated the therapeutic potential of beraprost for myocardial ischemia. Immediately after coronary ligation of Sprague-Dawley rats, beraprost (200 microg/kg/day) or saline was subcutaneously administered for 28 days. Four weeks after coronary ligation, administration of beraprost increased capillary density in ischemic myocardium, decreased infarct size, and improved cardiac function in rats with myocardial infarction. Beraprost markedly increased the number of CD34-positive cells and c-kit-positive cells in plasma. Also, four weeks after coronary ligation of chimeric rats with GFP-expressing bone marrow, bone marrow-derived cells were incorporated into the infarcted region and its border zone. Treatment with beraprost increased the number of GFP/von Willebrand factor-double-positive cells in the ischemic myocardium. These results suggest that beraprost has beneficial effects on ischemic myocardium partly by its ability to enhance neovascularization in ischemic myocardium by mobilizing bone marrow cells.

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.