Endogenous G-CSF and CD34+ cell mobilization after acute myocardial infarction

The Effect of Short-Term NAD3® Supplementation on Circulating Adult Stem Cells in Healthy Individuals Aged 40-70 Years

Objective This study aimed to assess the impact of acute and short-term supplementation with NAD3®, a theacrine-containing supplement, on circulating adult stem cell numbers in a healthy male and female population aged 40-70 years. Methods This was a double-blind, placebo-controlled crossover study with 12 participants randomized to receive either NAD3® or a placebo for seven days. Blood samples were collected after an overnight fast, before and after the seven-day supplementation period, and one and two hours after the final supplement dose. Using flow cytometry, circulating stem cells, including lymphocytoid CD34+ stem cells (CD45dimCD34+), stem cells associated with vascular maintenance and repair (CD45dimCD34+CD309+), CD34+ stem cells linked to a progenitor phenotype (CD45dimCD34+CD309neg), circulating endothelial stem cells (CD45negCD31+CD309+), and mesenchymal stem cells (CD45negCD90+) were quantified. Results Acute NAD3® supplementation did not result in the mobilization of stem cells from the bone marrow. However, seven days of daily NAD3® supplementation resulted in selective changes in circulating stem cell numbers. A significant time*treatment interaction was observed for CD45dimCD34+ cells (p=0.04) and CD45dimCD34+CD309neg cells (p=0.04), indicating a decrease in cell numbers with supplementation. There was also a trend toward an increase in circulating endothelial cells (p=0.08) with seven days of NAD3®supplementation. Conclusion Short-term NAD3® supplementation demonstrated an effect on the quantity of bone marrow-derived stem cells in circulation. The study suggests that this theacrine-containing supplement may play a role in modulating adult stem cell populations, emphasizing the potential impact of NAD3® on regenerative processes. Further research with extended supplementation periods and larger sample sizes is warranted to elucidate the functional consequences of these changes and explore the therapeutic implications for age-related declines in stem cell function.

Circulating progenitor cells and outcomes in patients with coronary artery disease

BACKGROUND

Low quantities of circulating progenitor cells (CPCs), specifically CD34+ populations, reflect impairment of intrinsic regenerative capacity. This study investigates the relationship between subsets of CPCs and adverse outcomes.

METHODS

1366 individuals undergoing angiography for evaluation of coronary artery disease (CAD) were enrolled into the Emory Cardiovascular Biobank. Flow cytometry identified CPCs as CD45med blood mononuclear cells expressing the CD34 epitope, with further enumeration of hematopoietic CPCs as CD133+/CXCR4+ cells and endothelial CPCs as vascular endothelial growth factor receptor-2 (VEGFR2+) cells. Adjusted Cox or Fine and Gray's sub-distribution hazard regression models analyzed the relationship between CPCs and 1) all-cause death and 2) a composite of cardiovascular death and non-fatal myocardial infarction (MI).

RESULTS

Over a median 3.1-year follow-up period (IQR 1.3-4.9), there were 221 (16.6%) all-cause deaths and 172 (12.9%) cardiovascular deaths/MIs. Hematopoietic CPCs were highly correlated, and the CD34+/CXCR4+ subset was the best independent predictor. Lower counts (≤median) of CD34+/CXCR4+ and CD34+/VEGFR2+ cells independently predicted all-cause mortality (HR 1.46 [95% CI 1.06-2.01], p = 0.02 and 1.59 [95% CI 1.15-2.18], p = 0.004) and cardiovascular death/MI (HR 1.50 [95% CI 1.04-2.17], p = 0.03 and 1.47 [95% CI 1.01-2.03], p = 0.04). A combination of low CD34+/CXCR4+ and CD34+/VEGFR2+ CPCs predicted all-cause death (HR 2.1, 95% CI 1.4-3.0; p = 0.0002) and cardiovascular death/MI (HR 2.0, 95% CI 1.3-3.2; p = 0.002) compared to those with both lineages above the cut-offs.

CONCLUSIONS

Lower levels of hematopoietic and endothelial CPCs indicate diminished endogenous regenerative capacity and independently correlate with greater mortality and cardiovascular risk in patients with CAD.

The association between baseline circulating progenitor cells and vascular function: The role of aging and risk factors

BACKGROUND

To investigate the cross-sectional and longitudinal relationships between vascular function and circulating progenitor cell (CPC) counts with respect to aging and exposure to risk factors.

METHODS

In 797 adult participants, CPCs were enumerated by flow cytometry as CD45med mononuclear cells expressing CD34 epitope and its subsets co-expressing CD133, and chemokine C-X-C motif receptor 4 (CXCR4+). Arterial stiffness was evaluated by tonometry-derived pulse wave velocity (PWV) and microvascular function was assessed as digital reactive hyperemia index (RHI).

RESULTS

In cross-sectional analyses, for every doubling in CD34+ cell counts, PWV was 15% higher and RHI was 9% lower, after adjusting for baseline characteristics and risk factors (p for all < 0.01). There were significant CPC-by-age-by-risk factor interactions (p <0.05) for both vascular measures. Among younger subjects (< 48 years), CPC counts were higher in those with risk factors and vascular function was better in those with higher compared to those with lower CPC counts (p for all < 0.0l). In contrast, in older participants, CPCs were not higher in those with risk factors, and vascular function was worse compared to the younger age group. A lower CPC count at baseline was an independent predictor of worsening vascular function during 2-year follow-up.

CONCLUSION

A higher CPC count in the presence of risk factors is associated with better vascular function among younger individuals. There is no increase in CPC count with risk factors in older individuals who have worse vascular function. Moreover, a higher CPC count is associated with less vascular dysfunction with aging.

Cardioprotective Mechanisms of Interrupted Anesthetic Preconditioning with Sevoflurane in the Setting of Ischemia/Reperfusion Injury in Rats

Background: Anesthetic preconditioning (AP) is known to mimic ischemic preconditioning. The purpose of this study was to investigate the effects of an interrupted sevoflurane administration protocol on myocardial ischemia/reperfusion (I/R) injury. Methods: Male Wistar rats (n = 60) were ventilated for 30 min with room air (control group, CG) or with a mixture of air and sevoflurane (1 minimum alveolar concentration—MAC) in 5-min cycles, alternating with 5-min wash-out periods (preconditioned groups). Cytokines implicated in the AP response were measured. An (I/R) lesion was produced immediately after the sham intervention (CG) and preconditioning protocol (early AP group, EAPG) or 24 h after the intervention (late AP group, LAPG). The area of fibrosis, the degree of apoptosis and the number of c-kit+ cells was estimated for each group. Results: Cytokine levels were increased post AP. The area of fibrosis decreased in both EAPG and LAPG compared to the CG (p < 0.0001). When compared to the CG, the degree of apoptosis was reduced in both LAPG (p = 0.006) and EAPG (p = 0.007) and the number of c-kit+ cells was the greatest for the LAPG (p < 0.0001). Conclusions: Sevoflurane preconditioning, using an interrupted anesthesia protocol, is efficient in myocardial protection and could be beneficial to reduce perioperative or periprocedural ischemia in patients with increased cardiovascular risk.

Inflammatory markers in acute myocardial infarction and the correlation with the severity of coronary heart disease

INTRODUCTION

The inflammatory hypothesis of atherosclerosis is appealing in acute coronary syndromes, but the dynamics and precise role are not established.

OBJECTIVES

The study investigates the levels of C reactive protein (CRP), interleukin 1β (IL-1β) and stromal-derived factor 1α (SDF-1α) at the time of acute myocardial infarction (AMI) and at 1 and 6 months afterwards, compared with a control group.

RESULTS

In the acute phase of AMI, CRP and SDF-1α were significantly higher, while IL-1β showed lower levels compared with controls. CRP positively correlated with coronary stenosis severity (rho = 0.3, p=.05) and negatively related with left ventricle ejection fraction (LVEF) at 1 month (rho= -0.43, p=.05). IL-1β weakly correlated with the severity of coronary lesions (rho =0.29, p=.02) and strongly with LVEF (rho= -0.8, p=.05). SDF-1α, slightly correlated with LVEF at 1 month (rho = 0.22, p=.01) and with the severity of coronary atherosclerosis (rho= -0.41, p=.003).

CONCLUSIONS

CRP, IL-1β and SDF-1α have important dynamic in the first 6 months after AMI and CRP and SDF-1α levels correlated with the severity of coronary lesions and LVEF at 1 month after the acute ischaemic event.

Clinical Significance of Electronegative Low-Density Lipoprotein Cholesterol in Atherothrombosis

Despite the numerous risk factors for atherosclerotic cardiovascular diseases (ASCVD), cumulative evidence shows that electronegative low-density lipoprotein (L5 LDL) cholesterol is a promising biomarker. Its toxicity may contribute to atherothrombotic events. Notably, plasma L5 LDL levels positively correlate with the increasing severity of cardiovascular diseases. In contrast, traditional markers such as LDL-cholesterol and triglyceride are the therapeutic goals in secondary prevention for ASCVD, but that is controversial in primary prevention for patients with low risk. In this review, we point out the clinical significance and pathophysiological mechanisms of L5 LDL, and the clinical applications of L5 LDL levels in ASCVD can be confidently addressed. Based on the previously defined cut-off value by receiver operating characteristic curve, the acceptable physiological range of L5 concentration is proposed to be below 1.7 mg/dL. When L5 LDL level surpass this threshold, clinically relevant ASCVD might be present, and further exams such as carotid intima-media thickness, pulse wave velocity, exercise stress test, or multidetector computed tomography are required. Notably, the ultimate goal of L5 LDL concentration is lower than 1.7 mg/dL. Instead, with L5 LDL greater than 1.7 mg/dL, lipid-lowering treatment may be required, including statin, ezetimibe or PCSK9 inhibitor, regardless of the low-density lipoprotein cholesterol (LDL-C) level. Since L5 LDL could be a promising biomarker, we propose that a high throughput, clinically feasible methodology is urgently required not only for conducting a prospective, large population study but for developing therapeutics strategies to decrease L5 LDL in the blood.

Why are cardiovascular diseases more common among patients with severe mental illness? The potential involvement of electronegative low-density lipoprotein (LDL) L5

Despite tremendous efforts of experimental and clinical studies and knowledge, the pathophysiology of severe mental illness (SMI), including bipolar disorder (BD), unipolar depression (mood disorders, MD), and schizophrenia (SCZ), remains poorly understood. Besides their chronic course and high prevalence in society, mental and somatic comorbidities are really serious problems; patients with these disorders have increased risk of cardiovascular (CV) diseases (CVD) including coronary artery diseases (CAD, i.e. myocardial infarction and angina), stroke, sudden cardiac death, hypertension, cardiomyopathy, arrhythmia, and thromboembolic disease. Although it is determined that triglycerides, cholesterol, glucose, and low-density lipoprotein (LDL) levels are increased in MD and SCZ, the underlying reason remains unknown. Considering this, we propose that electronegative LDL (L5) is probably the main crucial element to understanding CVD induced by SMI and to discovering novel remedial approaches for these diseases. When it is hypothesized that L5 is greatly presupposed in CV system abnormalities, it follows that the anti-L5 therapies and even antioxidant treatment options may open new therapeutic opportunities to prevent CVD diseases secondary to SMI. In this review article, we tried to bring a very original subject to the attention of readers who are interested in lipoprotein metabolism in terms of experimental, clinical, and cell culture studies that corroborate the involvement of L5 in physiopathology of CVD secondary to SMI and also the new therapeutic approaches for these disorders.

Stem Cell Homing: a Potential Therapeutic Strategy Unproven for Treatment of Myocardial Injury

Despite advances in the prevention and therapeutic modalities of ischemic heart disease, morbidity and mortality post-infarction heart failure remain big challenges in modern society. Stem cell therapy is emerging as a promising therapeutic strategy. Stem cell homing, the ability of stem cells to find their destination, is receiving more attention. Identification of specific cues and understanding the signaling pathways that direct stem cells to targeted destination will improve stem cell homing efficiency. This review discusses the cellular and molecular mechanism of stem cell homing at length in the light of literature and analyzes the problem and considerations of this approach as a treatment strategy for the treatment of ischemic heart disease clinically.

Progenitor Cells and Clinical Outcomes in Patients With Acute Coronary Syndromes

RATIONALE

Circulating progenitor cells (CPCs) mobilize in response to ischemic injury, but their predictive value remains unknown in acute coronary syndrome (ACS).

OBJECTIVE

We aimed to investigate the number of CPCs in ACS compared with those with stable coronary artery disease (CAD), relationship between bone marrow PCs and CPCs, and whether CPC counts predict mortality in patients with ACS.

METHODS AND RESULTS

In 2028 patients, 346 had unstable angina, 183 had an acute myocardial infarction (AMI), and the remaining 1499 patients had stable CAD. Patients with ACS were followed for the primary end point of all-cause death. CPCs were enumerated by flow cytometry as mononuclear cells expressing a combination of CD34+, CD133+, vascular endothelial growth factor receptor 2+, or chemokine (C-X-C motif) receptor 4+. CPC counts were higher in subjects with AMI compared those with stable CAD even after adjustment for age, sex, race, body mass index, renal function, hypertension, diabetes mellitus, hyperlipidemia, and smoking; CD34+, CD34+/CD133+, CD34+/CXCR4+, and CD34+/VEGFR2+ CPC counts were 19%, 25%, 28%, and 142% higher in those with AMI, respectively, compared with stable CAD. There were strong correlations between the concentrations of CPCs and the PC counts in bone marrow aspirates in 20 patients with AMI. During a 2 (interquartile range, 1.31-2.86)-year follow-up period of 529 patients with ACS, 12.4% died. In Cox regression models adjusted for age, sex, body mass index, heart failure history, estimated glomerular filtration rate, and AMI, subjects with low CD34+ cell counts had a 2.46-fold (95% confidence interval, 1.18-5.13) increase in all-cause mortality, P=0.01. CD34+/CD133+ and CD34+/CXCR4+, but not CD34+/VEGFR2+ PC counts, had similar associations with mortality. Results were validated in a separate cohort of 238 patients with ACS.

CONCLUSIONS

CPC levels are significantly higher in patients after an AMI compared with those with stable CAD and reflect bone marrow PC content. Among patients with ACS, a lower number of hematopoietic-enriched CPCs are associated with a higher mortality.

Increased haematopoietic activity in patients with atherosclerosis

Aims

Experimental work posits that acute ischaemic events trigger haematopoietic activity, driving monocytosis, and atherogenesis. Considering the chronic low-grade inflammatory state in atherosclerosis, we hypothesized that haematopoietic hyperactivity is a persistent feature in cardiovascular disease (CVD). Therefore, we aimed to assess the activity of haematopoietic organs and haematopoietic stem and progenitor cells (HSPCs) in humans.

Methods and results

First, we performed 18F-fluorodeoxyglucose positron emission tomographic (18F-FDG PET) imaging in 26 patients with stable atherosclerotic CVD (ischaemic event >12 months ago), and 25 matched controls. In splenic tissue, 18F-FDG uptake was 2.68 ± 0.65 in CVD patients vs. 1.75 ± 0.54 in controls (1.6-fold higher; P< 0.001), and in bone marrow 3.20 ± 0.76 vs. 2.72 ± 0.46 (1.2-fold higher; P = 0.003), closely related to LDL cholesterol levels (LDLc, r = 0.72). Subsequently, we determined progenitor potential of HSPCs harvested from 18 patients with known atherosclerotic CVD and 30 matched controls; both groups were selected from a cohort of cancer patients undergoing autologous stem cell transplantation. In CVD patients, the normalized progenitor potential, expressed as the number of colony-forming units-granulocyte/monocyte (CFU-GM) colonies/CD34+ cell, was 1.6-fold higher compared with matched controls (P < 0.001). Finally, we assessed the effects of native and oxidized lipoproteins on HSPCs harvested from healthy donors in vitro. Haematopoietic stem and progenitor cells displayed a 1.5-fold increased CFU-GM capacity in co-culture with oxidized LDL in vitro (P = 0.002), which was inhibited by blocking oxidized phospholipids via E06 (P = 0.001).

Conclusion

Collectively, these findings strengthen the case for a chronically affected haematopoietic system, potentially driving the low-grade inflammatory state in patients with atherosclerosis.

Electronegative L5-LDL induces the production of G-CSF and GM-CSF in human macrophages through LOX-1 involving NF-κB and ERK2 activation

BACKGROUND AND AIMS

Circulating levels of granulocyte colony-stimulating factor (G-CSF) and granulocyte macrophage colony-stimulating factor (GM-CSF) are associated with the severity of acute myocardial infarction (AMI). However, what causes increases in G-CSF and GM-CSF is unclear. In this study, we investigated whether L5-low-density lipoprotein (LDL), a mildly oxidized LDL from AMI, can induce G-CSF and GM-CSF production in human macrophages.

METHODS

L1-LDL and L5-LDL were isolated through anion-exchange chromatography from AMI plasma. Human macrophages derived from THP-1 and peripheral blood mononuclear cells were treated with L1-LDL, L5-LDL, or copper-oxidized LDL (Cu-oxLDL) and G-CSF and GM-CSF protein levels in the medium were determined. In addition, the effects of L5-LDL on G-CSF and GM-CSF production were tested in lectin-type oxidized LDL receptor-1 (LOX-1), CD36, extracellular signal-regulated kinase (ERK) 1, and ERK2 knockdown THP-1 macrophages.

RESULTS

L5-LDL but not L1-LDL or Cu-oxLDL significantly induced production of G-CSF and GM-CSF in macrophages. In vitro oxidation of L1-LDL and L5-LDL altered their ability to induce G-CSF and GM-CSF, suggesting that the degree of oxidation is critical for the effects. Knockdown and antibody neutralization experiments suggested that the effects were caused by LOX-1. In addition, nuclear factor (NF)-κB and ERK1/2 inhibition resulted in marked reductions of L5-LDL-induced G-CSF and GM-CSF production. Moreover, knockdown of ERK2, but not ERK1, hindered L5-LDL-induced G-CSF and GM-CSF production.

CONCLUSIONS

The results indicate that L5-LDL, a naturally occurring mild oxidized LDL, induced G-CSF and GM-CSF production in human macrophages through LOX-1, ERK2, and NF-κB dependent pathways.

Granulocyte colony-stimulating factor for the treatment of cardiovascular diseases: An update with a critical appraisal

Heart failure and acute myocardial infarction are conditions that are associated with high morbidity and mortality. Significant dysfunction of the heart muscle can occur as the consequence of end-stage chronic cardiovascular diseases or acute ischemic events that are marked by large infarction area and significant tissue necrosis. Despite the remarkable improvement of conventional treatments, a substantial proportion of patients still develops severe heart failure that can only be resolved by heart transplantation or mechanical device implantation. Therefore, novel approaches based on stem-cell therapy can directly modify the disease process and alter its prognosis. The ability of the stem-cells to modify and repair the injured myocardium is a challenging but intriguing concept that can potentially replace expensive and invasive methods of treatment that are associated with increased risks and significant financial costs. In that sense, granulocyte colony-stimulating factor (G-CSF) seems as an attractive treatment approach. Based on the series of pre-clinical experiments and a limited amount of clinical data, it was demonstrated that G-CSF agents possess the ability to mobilize stem-cells from bone marrow and induce their differentiation into cardiomyocytes or endothelial cells when brought into contact with injured regions of the myocardium. However, clinical benefits of G-CSF use in damaged myocardium remain unclear and are the topic of expert discussion. The main goal of this review is to present relevant and up-to-date evidence on G-CSF therapy use in pre-clinical models and in humans and to provide a rationale for its potential clinical applications in the future.

A novel recombinant antibody specific to full-length stromal derived factor-1 for potential application in biomarker studies

Background

Stromal derived factor-1α (SDF-1α/CXCL12) is a chemokine that is up-regulated in diseases characterised by tissue hypoxia, including myocardial infarction, ischaemic cardiomyopathy and remote ischaemic conditioning (RIC), a technique of cyclical, non-injurious ischaemia applied remote from the heart that protects the heat from lethal ischaemia-reperfusion injury. Accordingly, there is considerable interest in SDF-1α as a potential biomarker of such conditions. However, SDF-1α is rapidly degraded and inactivated by dipeptidyl peptidase 4 and other peptidases, and the kinetics of intact SDF-1α remain unknown.

Methods & results

To facilitate investigation of full-length SDF-1α we established an ELISA using a novel recombinant human antibody we developed called HCI.SDF1. HCI.SDF1 is specific to the N-terminal sequence of all isoforms of SDF-1 and has a comparable K_D to commercially available antibodies. Together with a detection antibody specific to the α-isoform, HCI.SDF1 was used to specifically quantify full-length SDF-1α in blood for the first time. Using RIC applied to the hind limb of Sprague-Dawley rats or the arms of healthy human volunteers, we demonstrate an increase in SDF-1α using a commercially available antibody, as previously reported, but an unexpected decrease in full-length SDF-1α after RIC in both species.

Conclusions

We report for the first time the development of a novel recombinant antibody specific to full-length SDF-1. Applied to RIC, we demonstrate a significant decrease in SDF-1α that is at odds with the literature and suggests a need to investigate the kinetics of full-length SDF-1α in conditions characterised by tissue hypoxia.

Circulating progenitor cells and coronary microvascular dysfunction: Results from the NHLBI-sponsored Women's Ischemia Syndrome Evaluation - Coronary Vascular Dysfunction Study (WISE-CVD)

BACKGROUND AND AIMS

Ischemia stimulates a reparative response resulting in mobilization of circulating progenitor cells (CPCs). We hypothesized that women with chronic myocardial ischemia from coronary microvascular disease (CMD) will mobilize CPCs.

METHODS

In 123 women with ischemic symptoms and signs but no obstructive coronary artery disease (CAD) enrolled in the Women's Ischemia Syndrome Evaluation - Coronary Vascular Dysfunction Study (WISE-CVD), we measured coronary flow reserve (CFR) in response to intracoronary adenosine. Peripheral blood CPCs were measured using flow cytometry for expression of CD34, CD133, CXCR4, and VEGFR2.

RESULTS

Subjects were 53 ± 11 years, BMI 30 ± 8; 44% hypertensive, 11% diabetic, 23% hyperlipidemic and 7% smokers. Lower CFR correlated inversely with higher levels of hematopoietic-enriched CD34+ (r = -0.23, p = 0.011), CD34+/CD133+ (r = -0.24, p = 0.008), and CD34+/CXCR4+ (r = -0.19, p = 0.036) cells. In multivariable regression analyses, after adjusting for traditional cardiovascular risk factors, lower CFR remained significantly associated with elevated levels of CD34+ (β -0.18, p = 0.042), CD34+/CD133+ (β -0.24, p = 0.036), and CD34+/CXCR4+ (β -0.22, p = 0.050) cells. We found no association between CFR and CD34+/VEGFR2+ cells.

CONCLUSIONS

In women with non-obstructive CAD, impaired CFR is associated with higher levels of CPCs, suggesting that chronic myocardial ischemia from CMD stimulates CPC mobilization. The functional significance of elevated CPCs in these subjects requires further investigation as a potential biomarker and treatment target.

Age and Human Regenerative Capacity Impact of Cardiovascular Risk Factors

RATIONALE

We investigated aging of human endogenous reparative capacity and aimed to clarify whether it is affected by presence of cardiovascular disease or its risk factors (RFs).

OBJECTIVE

Circulating progenitor cell (PC) levels reflect endogenous regenerative potential. The effect on PC of healthy aging compared with aging with RFs or cardiovascular disease (CVD) is unknown. We examined whether exposure to RF and CVD leads to an accelerated decline in circulating PC with increasing age.

METHODS AND RESULTS

In 2792 adult subjects, 498 were free of RFs (smoking, diabetes mellitus, hypertension, or hyperlipidemia), 1036 subjects had 1 to 2 RF, and 1253 had ≥3 RFs or CVD. PC were enumerated by flow cytometry as CD45(med+) mononuclear cells expressing CD34 and subsets coexpressing CD133, CXCR4, and vascular endothelial growth factor receptor-2 epitopes. Younger age, male sex, and larger body size correlated with higher PC counts (P<0.01). After multivariable adjustment, both age and RF categories were independently associated with PC counts (P<0.05), with lower PC counts in older subjects and those with higher RF burden or CVD. PC counts remained unchanged with increasing age in healthy individuals. There were significant interactions between age and RF categories (P≤0.005), such that for younger subjects (<40 years), RFs were associated with increased PC counts, whereas for older subjects (>60 years), RFs and CVD were associated with lower PC counts.

CONCLUSIONS

Circulating PC levels do not decline with healthy aging; RF exposure at a younger age stimulates PC mobilization, whereas continued exposure is associated with lower PC levels in later life. Over the lifespan, exposure to RFs and CVD is associated with an initial stimulation and subsequent decline in circulating PC levels, which reflect endogenous regenerative capacity.

Myocardial Ischemia Induces SDF-1α Release in Cardiac Surgery Patients

In the present observational study, we measured serum levels of the chemokine stromal cell-derived factor-1α (SDF-1α) in 100 patients undergoing cardiac surgery with cardiopulmonary bypass at seven distinct time points including preoperative values, myocardial ischemia, reperfusion, and the postoperative course. Myocardial ischemia triggered a marked increase of SDF-1α serum levels whereas cardiac reperfusion had no significant influence. Perioperative SDF-1α serum levels were influenced by patients' characteristics (e.g., age, gender, aspirin intake). In an explorative analysis, we observed an inverse association between SDF-1α serum levels and the incidence of organ dysfunction. In conclusion, time of myocardial ischemia was identified as the key stimulus for a significant upregulation of SDF-1α, indicating its role as a marker of myocardial injury. The inverse association between SDF-1α levels and organ dysfunction association encourages further studies to evaluate its organoprotective properties in cardiac surgery patients.

The combined effect of subcutaneous granulocyte- colony stimulating factor and myocardial contrast echocardiography with intravenous infusion of sulfur hexafluoride on post-infarction left ventricular function, the RIGENERA 2.0 trial: study protocol for a randomized controlled trial

BACKGROUND

Several clinical trials and recent meta-analyses have demonstrated that administration of recombinant human granulocyte-colony stimulating factor (G-CSF) is safe and, only in patients with large acute myocardial infarction (AMI), is associated with an improvement in left ventricular ejection fraction. Moreover, the mobilization and engraftment of the bone marrow-derived cells may differ significantly among patients, interfering with the restoration of left ventricular function after treatment. Therefore, the clinical potential application of the G-CSF has not yet been fully elucidated.

METHODS/DESIGN

The RIGENERA 2.0 trial is a multicenter, phase II, placebo-controlled, randomized, open-label, with blinded evaluation of endpoints (PROBE) trial in which 120 patients with an acute ST-elevation myocardial infarction (STEMI) undergoing successful revascularization but with residual myocardial dysfunction will be enrolled. In cases where there is a left ventricular ejection fraction (LVEF) ≤ 45% the patient will be electronically randomized (1:1 ratio) to receive either subcutaneous recombinant human G-CSF (group 1) or placebo (group 2) both added on top of optimal standard of care. Both groups will undergo myocardial contrast echocardiography with intravenous infusion of sulfur hexafluoride (MCE) whilst undergoing the echocardiogram. The primary efficacy endpoint is the evaluation of the LVEF at 6 months after AMI assessed by cardiac magnetic resonance. Secondary efficacy endpoints are the evaluation of LVEF at 6 months after AMI assessed by echocardiography, left ventricular end-diastolic volume (LVEDV) and left ventricular end-systolic volume (LVESV) assessed by cardiac magnetic resonance and echocardiography at 6 months, together with the incidence of major adverse clinical events (MACE) defined as death, myocardial infarction, sustained cardiac arrhythmias, cardiogenic shock, stroke and re-hospitalization due to heart failure at 1 year.

DISCUSSION

The RIGENERA 2.0 trial will test whether G-CSF administration and MCE, through the enhancement of the bone marrow-derived cells homing in the myocardium, determines an improvement in regional and global contractile function, myocardial perfusion and infarct extension in patients with large AMI. The results of the present study are expected to envision routine clinical use of this safe, affordable and reproducible approach in patients with successful revascularization after AMI.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02502747 (29 June 2015); EudraCT: 2015-002189-21 (10 July 2015).

Human mesenchymal stem cells labelled with dye-loaded amorphous silica nanoparticles: long-term biosafety, stemness preservation and traceability in the beating heart

BACKGROUND

Treatment of myocardial infarction with mesenchymal stem cells (MSCs) has proven beneficial effects in both animal and clinical studies. Engineered silica nanoparticles (SiO2-NPs) have been extensively used as contrast agents in regenerative medicine, due to their resistance to degradation and ease of functionalization. However, there are still controversies on their effective biosafety on cellular systems. In this perspective, the aims of the present study are: 1) to deeply investigate the impact of amorphous 50 nm SiO2-NPs on viability and function of human bone marrow-derived MSCs (hMSCs); 2) to optimize a protocol of harmless hMSCs labelling and test its feasibility in a beating heart model.

RESULTS

Optimal cell labelling is obtained after 16 h exposure of hMSCs to fluorescent 50 nm SiO2-NPs (50 µg mL(-1)); interestingly, lysosomal activation consequent to NPs storage is not associated to oxidative stress. During prolonged culture hMSCs do not undergo cyto- or genotoxicity, preserve their proliferative potential and their stemness/differentiation properties. Finally, the bright fluorescence emitted by internalized SiO2-NPs allows both clear visualization of hMSCs in normal and infarcted rat hearts and ultrastructural analysis of cell engraftment inside myocardial tissue.

CONCLUSIONS

Overall, 50 nm SiO2-NPs display elevated compatibility with hMSCs in terms of lack of cyto- and genotoxicity and maintenance of important features of these cells. The demonstrated biosafety, combined with proper cell labelling and visualization in histological sections, make these SiO2-NPs optimal candidates for the purpose of stem cell tracking inside heart tissue.

Granulocyte-colony stimulating factor for large anterior ST-elevation myocardial infarction: rationale and design of the prospective randomized phase III STEM-AMI OUTCOME trial

BACKGROUND

Granulocyte-colony stimulating factor (G-CSF) has been clinically tested in ST-elevation myocardial infarction (STEMI) with mixed results. Our 3-year follow-up data from STEM-AMI trial documented a sustained benefit of G-CSF on adverse ventricular remodeling after large anterior STEMI, when administered early and at a high-dose in patients with left ventricular (LV) dysfunction. The Aim of the present trial is to establish whether G-CSF improves hard clinical long-term outcomes.

METHODS

The STEM-AMI OUTCOME is a prospective, multicenter, randomized, open-label, phase III trial. It will include 1,530 patients with anterior STEMI undergoing primary percutaneous coronary intervention 2 to 24 hours after symptoms onset and with LV ejection fraction ≤45% after successful reperfusion. Patients will be randomized 1:1 to G-CSF and/or standard treatment. The primary end point is a reduced occurrence of all-cause death, recurrence of myocardial infarction, or hospitalization due to heart failure in G-CSF-treated patients. Left ventricular remodeling will be assessed via cardiac ultrasound and a substudy with cardiac magnetic resonance will be carried out in 120 subjects. Accrual and follow-up periods will last 3 and 2 years, respectively.

CONCLUSIONS

The STEM-AMI OUTCOME study is designed to be a rigorous controlled phase III trial with adequate statistical power to conclusively assess efficacy of G-CSF treatment in STEMI.

Immunologic Network and Response to Intramyocardial CD34+ Stem Cell Therapy in Patients With Dilated Cardiomyopathy

BACKGROUND

Although stem cell therapy (SCT) is emerging as a potential treatment for patients with dilated cardiomyopathy (DCM), clinical response remains variable. Our objective was to determine whether baseline differences in circulating immunologic and nonimmunologic biomarkers may help to identify patients more likely to respond to intramyocardial injection of CD34(+)-based SCT.

METHODS AND RESULTS

We enrolled from January 3, 2011 to March 5, 2012 37 patients with longstanding DCM (left ventricular ejection fraction [LVEF] <40%, New York Heart Association functional class III) who underwent peripheral CD34(+) stem cell mobilization with granulocyte colony-stimulating factor (G-CSF) and collection by means of apheresis. CD34(+) cells were labeled with (99m)Tc-hexamethylpropyleneamine oxime to allow assessment of stem cell retention at 18 hours. Response to SCT was predefined as an increase in LVEF of ≥5% at 3 months. The majority (84%) of patients were male with an overall mean LVEF of 27 ± 7% and a median N-terminal pro-B-type natriuretic peptide (NT-proBNP) level of 2,774 pg/mL. Nineteen patients (51%) were responders to SCT. There was no significant difference between responders and nonresponders regarding to age, sex, baseline LVEF, NT-proBNP levels, or 6-minute walking distance. With the use of a partial least squares (PLS) predictive model, we identified 9 baseline factors that were associated with both stem cell response and stem cell retention (mechanistic validation). Among the baseline factors positively associated with both clinical response and stem cell retention were G-CSF, SDF-1, LIF, MCP-1, and MCP-3. Among baseline factors negatively associated with both clinical response and retention were IL-12p70, FASL, ICAM-1, and GGT. A decrease in G-CSF at 3-month follow-up was also observed in responders compared with nonresponders (P = .02).

CONCLUSIONS

If further validated, baseline immunologic and nonimmunologic biomarkers may help to identify patients with DCM who are more likely to respond to CD34(+)-based SCT.

Left ventricular mass and progenitor cells in chronic heart failure patients

The aim of the study was to evaluate the association between circulating (CPCs) and endothelial (EPCs) progenitor cells and left ventricular (LV) remodeling in chronic heart failure (HF). 85 HF patients, ranging 29-89 years, 83.5% males, 45.9% ischemic, NYHA functional class II-IV, with a LV ejection fraction ≤40% were studied. LV ejection fraction, LV end-diastolic and end-systolic (LVESV) volumes, LV mass and tricuspid annular plane systolic excursion (TAPSE) were evaluated, and, when indicated, indexed for body surface area (BSA). CPCs and EPCs number was assessed using flow cytometry. CPCs were defined as CD34+, CD133+ and CD34+/CD133+. EPCs, identified through their expression of KDR, were defined as CD34+/KDR+, CD133+/KDR+ and CD34+/CD133+/KDR+. All EPCs were negatively related to LVESV/BSA (r = -0.24, p = 0.02 for all EPC's populations), and to LVmass/BSA (CD34+KDR+; r = -0.30, p = 0.005; CD133+KDR+; r = -0.31, p = 0.004; CD34+CD133+KDR+; r = -0.29, p = 0.007). No differences in EPCs levels in relation to cardiovascular risk factors, medications, etiology, age or gender were observed. CPCs number was higher in women, and lower in ischemic patients. In logistic regression analyses, the low EPCs' number was associated with an increased likelihood of abnormal LVmass/BSA. CPCs proved to be higher and EPCs lower in patients with severely abnormal LVmass/BSA (gr/m(2), ≥122 in women and ≥149 in men). Our results suggest a correlation between LV remodeling and progenitor cells. This is noteworthy considering that it has been suggested that bone marrow-derived EPCs participate in cardiac regeneration and function recovery in the setting of progressive HF.

Improvement of endurance of DMD animal model using natural polyphenols

Duchenne muscular dystrophy (DMD), the most common form of muscular dystrophy, is characterized by muscular wasting caused by dystrophin deficiency that ultimately ends in force reduction and premature death. In addition to primary genetic defect, several mechanisms contribute to DMD pathogenesis. Recently, antioxidant supplementation was shown to be effective in the treatment of multiple diseases including muscular dystrophy. Different mechanisms were hypothesized such as reduced hydroxyl radicals, nuclear factor-κB deactivation, and NO protection from inactivation. Following these promising evidences, we investigated the effect of the administration of a mix of dietary natural polyphenols (ProAbe) on dystrophic mdx mice in terms of muscular architecture and functionality. We observed a reduction of muscle fibrosis deposition and myofiber necrosis together with an amelioration of vascularization. More importantly, the recovery of the morphological features of dystrophic muscle leads to an improvement of the endurance of treated dystrophic mice. Our data confirmed that ProAbe-based diet may represent a strategy to coadjuvate the treatment of DMD.

Inflammatory markers in ST-elevation acute myocardial infarction

After acute myocardial infarction, ventricular remodeling is characterized by changes at the molecular, structural, geometrical and functional level that determine progression to heart failure. Inflammation plays a key role in wound healing and scar formation, affecting ventricular remodeling. Several, rather different, components of the inflammatory response were studied as biomarkers in ST-elevation acute myocardial infarction. Widely available and inexpensive tests, such as leukocyte count at admission, as well as more sophisticated immunoassays provide powerful predictors of adverse outcome in patients with ST-elevation acute myocardial infarction. We review the value of inflammatory markers in ST-elevation acute myocardial infarction and their association with ventricular remodeling, heart failure and sudden death. In conclusion, the use of these biomarkers may identify subjects at greater risk of adverse events and perhaps provide an insight into the mechanisms of disease progression.

Circulating CD133+ CD34+ progenitor cells and plasma stromal-derived factor-1alpha: predictive role in ischemic stroke patients

Circulating progenitor cells and stromal-derived factor-1alpha (SDF-1α) have been suggested to participate in tissue repair after ischemic injury. However, the predictive role of circulating CD133+ CD34+ progenitors and plasma SDF-1α in ischemic stroke (IS) patients remains unknown. In this study, we recruited 95 acute IS patients, 40 at-risk subjects, and 30 normal subjects. The National Institutes of Health Stroke Scale (NIHSS), infarct volume, and carotid intima-media thickness (IMT) were determined at day 1 and the modified Rankin scale (mRS) of functional outcome was assessed at day 21. The levels of circulating CD133+ CD34+ cells and plasma SDF-1α were determined by flow cytometry and enzyme-linked immunosorbent assay, respectively. Our data showed that: (1) the levels of CD133+ CD34+ cells were lower in at-risk subjects and IS patients at admission (day 1) when compared with normal controls; (2) the day 1 level of CD133+ CD34+ cells varied in IS subgroups and inversely correlated with NIHSS and carotid IMT and the level of SDF-1α inversely correlated with NIHSS and infarct volume; (3) the increment rates of circulating CD133+ CD34+ cells and plasma SDF-1α within the first week were correlated; and (4) patients with a higher level of CD133+ CD34+ cells at day 7 had a low mRS. The increased rate of CD133+ CD34+ cells in the first week was inversely associated with mRS. In conclusion, our findings demonstrate that the circulating CD133+ CD34+ progenitor cells and plasma SDF-1α can be used as predictive parameters for IS severity and outcome.

Endothelial progenitor cells--potential new avenues to improve neoangiogenesis and reendothelialization

The term endothelial progenitor cell (EPC) was established more than 10 years ago and is used to refer to a group of circulating cells that display endothelial lineage qualities and are able to home to areas of ischemia or vascular injury and to facilitate the repair of damaged blood vessels or develop new vessels as needed. This chapter reviews the current lineage relationships among all the cells called EPC and will clear the terminology used in EPC research. Furthermore, an overview of the clinical and in vitro research, as well as cytokine and drug interactions and potential EPC applications, is given.

Elevated plasma stromal-cell-derived factor-1 protein levels correlate with severity in patients with community-acquired pneumonia

BACKGROUND

The aim of this study was to investigate differential changes in plasma levels of stromal-cell-derived factor-1 (SDF-1) before and after antibiotic treatment in patients with community-acquired pneumonia (CAP) and observe the association between the severity of CAP and the plasma SDF-1 level.

METHODS

We gathered blood specimens from 61 adult CAP patients before and after antibiotic treatment and from 60 healthy controls to measure the plasma concentrations of SDF-1 by using an enzyme-linked immunosorbent assay.

RESULTS

The plasma SDF-1 concentration was elevated significantly in patients with CAP before receiving treatment compared with the controls and decreased significantly after the patients received treatment. Leukocyte (WBC) and neutrophil counts and C-reactive protein (CRP) levels decreased significantly after antibiotic treatment. Moreover, differences in the plasma concentration of SDF-1 were significantly correlated with PSI, CURB-65, and APACHE II scores (r = 0.389, P = 0.002, and n = 61; r = 0.449, P < 0.001, and n = 61; and r = 0.363, P = 0.004, and n = 61, resp.).

CONCLUSIONS

An elevated plasma SDF-1 concentration can be used as a biological marker for the early diagnosis of CAP and for the early detection of its severity.

Stromal derived factor 1α: a chemokine that delivers a two-pronged defence of the myocardium

Alleviating myocardial injury associated with ST elevation myocardial infarction is central to improving the global burden of coronary heart disease. The chemokine stromal cell-derived factor 1α (SDF-1α) has dual potential benefit in this regard. Firstly, SDF-1α is up-regulated in experimental and clinical studies of acute myocardial infarction (AMI) and regulates stem cell migration to sites of injury. SDF-1α delivery to the myocardium after AMI is associated with improved stem cell homing, angiogenesis, and left ventricular function in animal models, and improvements in heart failure and quality of life in humans. Secondly, SDF-1α may have a role in remote ischaemic conditioning (RIC), the phenomenon whereby non-lethal ischaemia–reperfusion applied to an organ or tissue remote from the heart protects the myocardium from lethal ischaemia–reperfusion injury (IRI). SDF-1α is increased in the serum of rats subjected to RIC and protects against myocardial IRI in ex vivo studies. Despite these potential pleiotropic effects, a limitation of SDF-1α is its short plasma half-life due to cleavage by dipeptidyl peptidase-4 (DPP-4). However, DPP-4 inhibitors increase the half-life of SDF-1α by preventing its degradation and are also protective against lethal IRI. In summary, SDF-1 potentially delivers a ‘two-pronged’ defence of the myocardium: acutely protecting it from IRI while simultaneously stimulating repair by recruiting stem cells to the site of injury. In this article we examine the evidence for acute and chronic cardioprotective roles of SDF-1α and discuss potential therapeutic manipulations of this mechanism with DPP-4 inhibitors to protect against lethal tissue injury in the clinical setting.

Regenerative therapy for cardiovascular disease

Recent insights into myocardial biology uncovered a hereto unknown regenerative capacity of the adult heart. The discovery of dividing cardiomyocytes and the identification and characterization of cardiac stem and progenitor cells with myogenic and angiogenic potential have generated new hopes that cardiac regeneration and repair might become a therapeutic option. During the past decade, multiple candidate cells have been proposed for cardiac regeneration, and their mechanisms of action in the myocardium have been explored. Initial clinical trials have focused on the use of bone marrow-derived cells to promote myocardial regeneration in ischemic heart disease and have yielded very mixed results, with no clear signs of clinically meaningful functional improvement. Although the efficiency of bona fide cardiomyocyte generation is generally low, stem cells delivered into the myocardium act mainly via paracrine mechanisms. More recent studies taking advantage of cardiac committed cells (eg, resident cardiac progenitor cells or primed cardiogenic mesenchymal stem cells) showed promising results in first clinical pilot trials. Also, transplantation of cardiomyogenic cells generated by induced pluripotent stem cells and genetic reprogramming of dividing nonmyocytes into cardiomyocytes may constitute attractive new regenerative approaches in cardiovascular medicine in the future. We discuss advantages and limitations of specific cell types proposed for cell-based therapy in cardiology and give an overview of the first clinical trials using this novel therapeutic approach in patients with cardiovascular disease.

Fibrosis markers and CRIM1 increase in chronic heart failure of increasing severity

BACKGROUND

Fibrosis suppressors/activators in chronic heart failure (CHF) is a topic of investigation.

AIM

To quantify serum levels of fibrosis regulators in CHF.

METHODS

ELISA tests were used to quantify fibrosis regulators, procollagen type-(PIP)I, (PIP)III, collagen-I, III, BMP1,2,3,7, SDF1α, CXCR4, fibulin 1,2,3, BMPER, CRIM1 and BAMBI in 66 CHF (NYHA class I, n = 9; II, n = 34; III n = 23), and in 14 controls.

RESULTS

In CHF, TGFβR2, PIPIII, SDF1α and CRIM1 were increased. PIPIII correlated with CRIM1.

CONCLUSIONS

The BMPs inhibitor CRIM1 is increased and correlates with higher levels of serum PIPIII showing an imbalance in favor of pro-fibrotic mechanisms in CHF.

Mesenchymal stem cells and their conditioned medium improve integration of purified induced pluripotent stem cell-derived cardiomyocyte clusters into myocardial tissue

Induced pluripotent stem cell-derived cardiomyocytes (iPS-CMs) might become therapeutically relevant to regenerate myocardial damage. Purified iPS-CMs exhibit poor functional integration into myocardial tissue. The aim of this study was to investigate whether murine mesenchymal stem cells (MSCs) or their conditioned medium (MScond) improves the integration of murine iPS-CMs into myocardial tissue. Vital or nonvital embryonic murine ventricular tissue slices were cocultured with purified clusters of iPS-CMs in combination with murine embryonic fibroblasts (MEFs), MSCs, or MScond. Morphological integration was assessed by visual scoring and functional integration by isometric force and field potential measurements. We observed a moderate morphological integration of iPS-CM clusters into vital, but a poor integration into nonvital, slices. MEFs and MSCs but not MScond improved morphological integration of CMs into nonvital slices and enabled purified iPS-CMs to confer force. Coculture of vital slices with iPS-CMs and MEFs or MSCs resulted in an improved electrical integration. A comparable improvement of electrical coupling was achieved with the cell-free MScond, indicating that soluble factors secreted by MSCs were involved in electrical coupling. We conclude that cells such as MSCs support the engraftment and adhesion of CMs, and confer force to noncontractile tissue. Furthermore, soluble factors secreted by MSCs mediate electrical coupling of purified iPS-CM clusters to myocardial tissue. These data suggest that MSCs may increase the functional engraftment and therapeutic efficacy of transplanted iPS-CMs into infarcted myocardium.

Impaired endothelial progenitor cell mobilization and dysfunctional bone marrow stroma in diabetes mellitus

Background

Circulating Endothelial Progenitor Cell (EPC) levels are reduced in diabetes mellitus. This may be a consequence of impaired mobilization of EPC from the bone marrow. We hypothesized that under diabetic conditions, mobilization of EPC from the bone marrow to the circulation is impaired –at least partly– due to dysfunction of the bone marrow stromal compartment.

Methods

Diabetes was induced in mice by streptozotocin injection. Circulating Sca-1⁺Flk-1⁺ EPC were characterized and quantified by flow cytometry at baseline and after mobilization with G-CSF/SCF injections. In vivo hemangiogenic recovery was tested by 5-FU challenge. Interaction within the bone marrow environment between CD34⁺ hematopoietic progenitor cells (HPC) and supporting stroma was assessed by co-cultures. To study progenitor cell–endothelial cell interaction under normoglycemic and hyperglycemic conditions, a co-culture model using E4Orf1-transfected human endothelial cells was employed.

Results

In diabetic mice, bone marrow EPC levels were unaffected. However, circulating EPC levels in blood were lower at baseline and mobilization was attenuated. Diabetic mice failed to recover and repopulate from 5-FU injection. In vitro, primary cultured bone marrow stroma from diabetic mice was impaired in its capacity to support human CFU-forming HPC. Finally, hyperglycemia hampered the HPC supportive function of endothelial cells in vitro.

Conclusion

EPC mobilization is impaired under experimental diabetic conditions and our data suggest that diabetes induces alterations in the progenitor cell supportive capacity of the bone marrow stroma, which could be partially responsible for the attenuated EPC mobilization and reduced EPC levels observed in diabetic patients.

[Factors influencing mobilisation of endothelial progenitor cells and angiogenic cytokines after an extensive acute myocardial infarction]

BACKGROUND AND OBJECTIVES

Following an acute myocardial infarction (AMI), bone-marrow derived endothelial progenitor cells (EPC) are mobilised into the peripheral blood. Our aim was to examine the factors influencing this spontaneous cell mobilisation.

PATIENTS AND METHODS

In this study we analysed 47 patients with extensive AMI (left ventricular ejection fraction [LVEF] <50% by echocardiography during the first week post-AMI); we studied the peripheral blood EPC populations expressing CD133(+), CD34(+), KDR(+), CXCR4(+), as well as the cytokines VEGF (vascular endothelial growth factor), SDF-1 (stromal cell-derived factor 1) and TSP-1 (thrombospondin 1), measured on day 5±2.5 after AMI.

RESULTS

The extension of AMI (CPK peak) correlated with the number of CD133(+) mobilised cells: (r=0.40; P=.011). Patients who did not receive perfusion during the acute phase (34%) had more CD34(+)CXCR4(+) cells with a median (interquartile ranges) of 2,401 (498-7,004) vs. 999 (100-1,600), P=.048, and strong correlations between VEGF and CD133(+)CD34(+)KDR(+) (r=.84; P<.01) and SDF-1 and CD34(+)CXCR4(+) (r=.67; P<.01), and between these 2 cytokines (r=.57; P=.01). In the reperfused patients, the correlation between VEGF and CD133(+)CD34(+)KDR(+) was lower (r=.38; P=.03) and the correlation between SDF-1 and CD34(+)CXCR4(+) and VEGF disappeared. Multivariate analysis showed that a VEGF >7pg/mL (P<.01) predicted the mobilisation of CD133(+)CD34(+)KDR(+), whereas hypertension showed a trend (P=.055). Diabetes (P=.045) predicted the number of CD34(+)CXCR4(+), with reperfusion treatment showing a trend in this subpopulation (P=.054).

CONCLUSIONS

Mobilisation of progenitor cells after AMI is influenced by factors such as diabetes and the cytokine VEGF. Hypertension and reperfusion therapy during the acute phase also tend to influence the cell response.

Phenotypic and functional alterations on inflammatory peripheral blood cells after acute myocardial infarction

The frequency and function of T cells, monocytes, and dendritic cell subsets were investigated in 12 patients after acute myocardial infarction (AMI)-(T0), 1 month after the episode (T1), and in 12 healthy individuals (HG). The cell characterization and the functional studies were performed by flow cytometry and by RT-PCR, after cell sorting. The most important findings at T0 moment, when compared with T1 and HG, were: a decrease in the frequency of IL-2-producing T cells; a lower frequency of TNF-α- and IL-6-producing monocytes, myeloid dendritic cells, and CD14(-/low)CD16(+)DCs; and a lower TNF-α mRNA expression, after sorting these cells. Moreover, the regulatory function of Treg cells, at T0 moment, was upregulated, based on the FoxP3, CTLA-4, and TGF-β mRNA expression increase. The majority of these phenotypic and functional alterations disappeared at T1. Our data demonstrate that AMI induces a significant change in the immune system homeostasis.

The cardioprotective effects of parathyroid hormone are independent of endogenous granulocyte-colony stimulating factor release

AIMS

Parathyroid hormone (PTH) administration after myocardial infarction (MI) is known to attenuate ischaemic cardiomyopathy. This effect mainly resulted from an increase in mobilization and homing of CD34+/CD45+ cells into the ischaemic myocardium. PTH-related stem cell mobilization was shown to be related to endogenous granulocyte-colony stimulating factor (G-CSF) release. The aim of our study is to determine the role of G-CSF on the cardioprotective effects of PTH.

METHODS AND RESULTS

G-CSF +/+ (C57BL/6) and G-CSF -/- mice were treated with PTH for 6 days after inducing a MI. The myocardial homing factor stromal cell-derived factor-1 (SDF-1) was analysed on day 2 with enzyme-linked immunosorbent assay. Stem cell populations in peripheral blood and hearts were examined by FACS on days 6 and 2, respectively. Cardiac function and immunohistochemistry were investigated on day 6 and day 30. PTH treatment resulted in a significant increase in CD45+/CD34+ cells in peripheral blood in G-CSF +/+ but not in G-CSF -/- mice. However, a significant increase in SDF-1 and enhanced migration of CD45+/CD34+ cells into the ischaemic myocardium was revealed after PTH administration in both G-CSF +/+ and G-CSF -/- mice. Enhanced stem cell homing was associated with improved cardiac function and post-MI survival after PTH treatment. Furthermore, infarct size, wall thickness, and neovascularization showed a significant improvement in both groups 30 days after MI.

CONCLUSION

The cardioprotective effects of PTH were shown to be independent of endogenous G-CSF release and therefore from stem cell mobilization. This puts more emphasis on the role of stem cell homing into ischaemic myocardium.

β-blockade protection of bone marrow following trauma: the role of G-CSF

BACKGROUND

Following severe trauma, there is a profound elevation of catecholamine that is associated with a persistent anemic state. We have previously shown that β-blockade (βB) prevents erythroid growth suppression and decreases hematopoietic progenitor cell (HPC) mobilization following injury. Under normal conditions, granulocyte colony stimulating factor (G-CSF) triggers the activation of matrix metalloprotease-9 (MMP-9), leading to the egress of progenitor cells from the bone marrow (BM). When sustained, this depletion of BM cellularity may contribute to BM failure. This study seeks to determine if G-CSF plays a role in the βB protection of BM following trauma.

METHODS

Male Sprague-Dawley rats were subjected to either unilateral lung contusion (LC) ± βB, hemorrhagic shock (HS) ± βB, or both LC/HS ± βB. Propranolol (βB) was given immediately following resuscitation. Animals were sacrificed at 3 and 24 h and HPC mobilization was assessed by evaluating BM cellularity and flow cytometric analysis of peripheral blood for HPCs. The concentration of G-CSF and MMP-9 was measured in plasma by ELISA.

RESULTS

BM cellularity is decreased at 3 h following LC, HS, and LC/HS. HS and LC/HS resulted in significant HPC mobilization in the peripheral blood. The addition of βB restored BM cellularity and reduced HPC mobilization. Three h following HS and LC/HS, plasma G-CSF levels more than double, however LC alone showed no change in G-CSF. βB significantly decreased G-CSF in both HS and LC/HS. Similarly, MMP-9 is elevated following LC/HS, and βB prevents this elevation (390 ± 100 pg/mL versus 275 ± 80 pg/mL).

CONCLUSION

βB protection of the BM following shock and injury may be due to reduced HPC mobilization and maintenance of BM cellularity. Following shock, there is an increase in plasma G-CSF and MMP-9, which is abrogated by βB and suggests a possible mechanism how βB decreases HPC mobilization thus preserving BM cellularity. In contrast, βB protection of BM following LC is not mediated by G-CSF. Therefore, the mechanism of progenitor cell mobilization from the BM is dependent on the type of injury.

Different clinical models of CD34 + cells mobilization in patients with cardiovascular disease

To test the role of necrosis, ischemia or both in bone marrow cells (BMC) mobilization in patients with cardiovascular disease. We studied three groups of patients: group 1, Iatrogenic Necrosis, with pure necrosis (28 patients undergoing transcatheter radiofrequency ablation); group 2, Ischemic Necrosis (30 patients with myocardial infarction); group 3, Pure Ischemia (24 patients with unstable angina). As control groups, we studied 27 patients with stable coronary artery disease (CAD), and 20 patients without CAD undergoing angiography for valvular diseases or cardiomiopathy. CD34 + cells and cytokines were evaluated at: T(0) (baseline), 48 h and 5, 7, 10, 14 days thereafter. We observed a significant increase of CD34 + cells at T(3) and T(4) only in Iatrogenic Necrosis and Ischemic Necrosis group. The peak of mobilization was observed ten days after the necrotic event (2.8 ± 1.4 vs. 5.9 ± 1.9 in the group 1, P = 0.03; and 3 ± 1.5 vs. 5.6 ± 2 in the group 2, P = 0.04; respectively). We found a good correlation between CD34 + and vascular endothelial growth factor (VEGF) and stromal derived factor (SDF-1α) peak values (r = 0.77 and r = 0.63, respectively). At multivariable analysis, myocardial necrosis (OR 3.5, 95%CI 2.2-4.2, P < 0.01), VEGF (OR 2, 95%CI 1.1-3, P = 0.01 as above versus below median value), and SDF-1α (OR 1.6, 95%CI 1.1-2.5, P = 0.02 as above versus below median value) emerged as independent predictors of C34 + cells increase. Myocardial necrosis with simultaneous elevation of VEGF and SDF-1α causes a significant CD34 + cells mobilization in patients with cardiovascular disease.

Myocardial production and release of MCP-1 and SDF-1 following myocardial infarction: differences between mice and man

Background

Stem cell homing to the heart is mediated by the release of chemo-attractant cytokines. Stromal derived factor -1 alpha (SDF-1a) and monocyte chemotactic factor 1(MCP-1) are detectable in peripheral blood after myocardial infarction (MI). It remains unknown if they are produced by, and released from, the heart in order to attract stem cells to repair the damaged myocardium.

Methods

Murine hearts were studied for expression of MCP-1 and SDF-1a at day 3 and day 28 following myocardial infarction to determine whether production is increased following MI. In addition, we studied the coronary artery and coronary sinus (venous) blood from patients with normal coronary arteries, stable coronary artery disease (CAD), unstable angina and MI to determine whether these cytokines are released from the heart into the systemic circulation following MI.

Results

Both MCP-1 and SDF-1a are constitutively produced and released by the heart. MCP-1 mRNA is upregulated following murine experimental MI, but SDF-1a is suppressed. There is less release of SDF-1a into the systemic circulation in patients with all stages of CAD including MI, mimicking the animal model. However MCP-1 release from the human heart following MI is also suppressed, which is the exact opposite of the animal model.

Conclusions

SDF-1a and MCP-1 release from the human heart are suppressed following MI. In the case of SDF-1a, the animal model appropriately reflects the human situation. However, for MCP-1 the animal model is the exact opposite of the human condition. Human observational studies like this one are paramount in guiding translation from experimental studies to clinical trials.

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.

Stem Cell Therapy in Acute Myocardial Infarction: A Pot of Gold or Pandora's Box

Stem cell therapy for conditions characterized by myocyte loss in myocardial infarction and heart failure is intuitively appealing. Stem cells from various sources, including heart itself in preclinical and animal studies, have shown the potential to improve the function of ventricular muscle after ischaemic injury. The clinical experience from worldwide studies have indicated the safety profile but with modest benefits. The predominant mechanisms of transplanted cells for improving cardiac function have pointed towards paracrine effects rather than transdifferentiation into cardiomyocytes. Thus, further investigations should be encouraged towards bench side and bedside to resolve various issues for ensuring the correct type and dosing of cells, time, and method of delivery and identify correct mechanism of functional improvement. An interdisciplinary effort at the scientific, clinical, and the government front will bring successful realization of this therapy for healing the heart and may convert what seems now a Pandora's Box into a Pot of Gold.

Stromal-derived factor-1[alpha] correlates with circulating endothelial progenitor cells and with acute lesion volume in stroke patients

BACKGROUND AND PURPOSE

Endothelial progenitor cells (EPC) are important participants of neovascularization and are mobilized through signaling with stromal-derived factor (SDF-1α), vascular endothelial growth factor (VEGF), granulocyte colony-stimulating factor, and stem cell factor. The association between EPC levels and these growth factors (GF) in acute stroke has not been previously established. We aimed to determine the association between EPC and these GF, and to elucidate a relationship between these GF and stroke severity in acute stroke patients.

METHODS

Seventeen patients were selected from 175 patients with imaging-confirmed acute ischemic stroke. EPC were quantified using CD34, CD133, and VEGF-R2 markers. Plasma VEGF, SDF-1α, granulocyte colony-stimulating factor, and stem cell factor were determined by enzyme-linked immunosorbent assay on days 1 and 3, and brain MRI was performed at baseline and on days 1 and 5 after the stroke onset.

RESULTS

Levels of SDF-1α strongly (r=0.6) correlated with the numbers of EPC subsets CD133(+)VEFG-R2(+) (P<0.004), CD34(+)VEGF-R2(+) (P<0.01), and CD34(+)CD133(+)VEGF-R2(+) (P<0.01) on day 1. Stem cell factor strongly (r=0.5) correlated with CD133(+)VEGF-R2(+) (P<0.05). SDF-1α moderately inversely (r=-0.49) correlated with baseline diffusion-weighted imaging lesion volumes (P<0.04). Median levels of SDF-1α (1561 pg/mL) increased (P<0.04) on day 3 compared to day 1 (1379 pg/mL). Similarly, VEGF at day 3 (95 pg/mL) increased (P<0.03) compared to day 1 (64 pg/mL).

CONCLUSIONS

These results indicate that SDF-1α and stem cell factor correlate with an increase in EPC early in ischemic stroke patients.