Mobilization of CD34+ KDR+ endothelial progenitor cells predicts target lesion revascularization

Adjunctive Cilostazol to Dual Antiplatelet Therapy to Enhance Mobilization of Endothelial Progenitor Cell in Patients with Acute Myocardial Infarction: A Randomized, Placebo-Controlled EPISODE Trial

Background: Endothelial progenitor cells (EPCs) have the potential to protect against atherothrombotic event occurrences. There are no data to evaluate the impact of cilostazol on EPC levels in high-risk patients. Methods: We conducted a randomized, double-blind, placebo-controlled trial to assess the effect of adjunctive cilostazol on EPC mobilization and platelet reactivity in patients with acute myocardial infarction (AMI). Before discharge, patients undergoing percutaneous coronary intervention (PCI) were randomly assigned to receive cilostazol SR capsule (200-mg) a day (n = 30) or placebo (n = 30) on top of dual antiplatelet therapy (DAPT) with clopidogrel and aspirin. Before randomization (baseline) and at 30-day follow-up, circulating EPC levels were analyzed using flow cytometry and hemostatic measurements were evaluated by VerifyNow and thromboelastography assays. The primary endpoint was the relative change in EPC levels between baseline and 30-day. Results: At baseline, there were similar levels of EPC counts between treatments, whereas patients with cilostazol showed higher levels of EPC counts compared with placebo after 30 days. Cilostazol versus placebo treatment displayed significantly higher changes in EPC levels between baseline and follow-up (ΔCD133⁺/KDR⁺: difference 216%, 95% confidence interval (CI) 44~388%, p = 0.015; ΔCD34⁺/KDR⁺: difference 183%, 95% CI 25~342%, p = 0.024). At 30-day follow-up, platelet reactivity was lower in the cilostazol group compared with the placebo group (130 ± 45 versus 169 ± 62 P2Y12 Reaction Unit, p = 0.009). However, there were no significant correlations between the changes of EPC levels and platelet reactivity. Conclusion: Adjunctive cilostazol on top of clopidogrel and aspirin versus DAPT alone is associated with increased EPC mobilization and decreased platelet reactivity in AMI patients, suggesting its pleiotropic effects against atherothrombotic events (NCT04407312).

Maintenance chemotherapy in children with ALL exerts metronomic-like thrombospondin-1 associated anti-endothelial effect

Maintenance chemotherapy is an important part of the treatment of ALL in children. It relies on the long-term oral administration of daily low-dose mercaptopurin and weekly low-dose methotrexate. Although it has been used in the clinic for decades, its mechanisms of action remain unclear. Here, we investigated different angiogenic and immune biomarkers to gain insights into the mechanisms of action of maintenance therapy in children with ALL. We thus monitored circulating endothelial cells (CEC), endothelial progenitor cells (EPC) and endothelial microparticles (EMP), pro-angiogenic factors (VEGF, VEGFR-1 and Ang-2), anti-angiogenic factor thrombospondin-1 (THBS1) and regulatory T lymphocytes (Treg) in 47 children with ALL during the maintenance phase of their treatment (at treatment initiation and after 6, 12 and 18 months). We observed a statistically significant decrease in EPC and EMP counts throughout the maintenance phase associated with a significant increase in THBS1 levels. No significant change was detected in other angiogenic markers or in Treg numbers.

The results presented here indicate that maintenance therapy in children with ALL exerts its antitumor activity at least in part through anti-angiogenic effects, similar to those induced by metronomic chemotherapy. Larger studies are now warranted to validate these findings and determine their clinical implications.

Levels of Circulating Progenitor Cells, Cardiovascular Outcomes and Death

Rationale:

Circulating progenitor cells (CPCs), including endothelial progenitor cells (EPCs) are biologically related to many aspects of cardiovascular disease, as they promote angiogenesis and vascular repair.

Objective:

We herein aimed to meta-analyze studies reporting the prognostic role of the CPC/EPC measure on cardiovascular outcomes and death.

Methods and Results:

We screened the English-language literature for longitudinal studies reporting the association between baseline CPC/EPC levels, future cardiovascular events, and death. We retrieved 28 studies, 21 of which contained poolable data and entered the meta-analysis, for a total of 4155 patients, mostly with a high baseline cardiovascular risk. Sixty percent of the studies met at least 11 of 16 items of quality assessment. Overall, reduced CPC/EPC levels were associated with a ≈2-fold increased risk of future cardiovascular events and cardiovascular death. The most predictive phenotype was CD34 + CD133 + : low versus high levels predicted cardiovascular events, restenosis after endovascular intervention, cardiovascular death, and all-cause mortality. Heterogeneity among studies and according to the CPC/EPC phenotype was generally high. Excluding studies for which the risk estimate had to be extrapolated or limiting the analyses to higher quality studies still indicated a significant risk for future cardiovascular events and death in patients with low versus high progenitor cell counts.

Conclusions:

This meta-analysis shows that a reduction in the levels of circulating cells putatively provided with vasculoregenerative properties represents a risk factor for adverse cardiovascular outcomes and death.

Short-term exercise training improves flow-mediated dilation and circulating angiogenic cell number in older sedentary adults

Cardiovascular disease risk increases with age due, in part, to impaired endothelial function and decreased circulating angiogenic cell (CAC) number and function. We sought to determine if 10 days of aerobic exercise training improves endothelial function, CAC number, and intracellular redox balance in older sedentary adults. Eleven healthy subjects (4 men, 7 women), 61 ± 2 years of age participated in 60 min of aerobic exercise at 70% maximal oxygen consumption for 10 consecutive days while maintaining body weight. Before and after training, endothelial function was measured as flow-mediated dilation of the brachial artery and fasting blood was drawn to enumerate 3 CAC subtypes. Intracellular reactive oxygen species (ROS) and nitric oxide (NO) in CD34+ CACs were measured using fluorescent probes and reinforced via real-time quantitative polymerase chain reaction. Flow-mediated dilation improved significantly following training (10% ± 1.3% before vs. 16% ± 1.4% after training; P < 0.05). Likewise, CD34+/KDR+ number increased 104% and KDR+ number increased 151% (P < 0.05 for both), although CD34+ number was not significantly altered (P > 0.05). Intracellular NO and ROS levels in CD34+ CACs were not different after training (P > 0.05 for both). Messenger RNA expression of SOD1, endothelial nitric oxide synthase, and NADPH oxidase 2 and neutrophil cytosolic factor 1 in CD34+ CACs was not significantly altered with training (P > 0.05). In conclusion, 10 consecutive days of aerobic exercise increased flow-mediated dilation and CAC number in older, previously sedentary adults, but did not affect intracellular redox balance in CD34+ CACs. Overall, these data indicate that even short-term aerobic exercise training can have a significant impact on cardiovascular disease risk factors.

Association between mobilization of circulating endothelial progenitor cells and time or degree of injury from angioplasty in patients with exertional angina: A prospective study

The aim of the present study was to investigate the effect of coronary artery angioplasty on the recruitment of circulating endothelial progenitor cells (EPCs) in patients with angina pectoris. A total of 66 patients treated by coronary stenting were enrolled in the PCI group and 17 patients that underwent angiography alone were enrolled in the control group. The EPC count in the blood was measured by flow cytometry prior to and at 1, 3, 5, 7 and 24 h following angioplasty in the percutaneous coronary intervention (PCI) group, and at three time-points following angiography in the control group. Differences between the two groups included the characteristics of the coronary artery lesions, the incidence of diabetes and family history of coronary heart disease. The mean surface area of the stent deployed was 335.59±234.99 mm². No significant change in EPC count was measured in the control group. In the PCI group, a moderate and delayed increase in the number of cluster of differentiation (CD)34⁺/kinase domain receptor (KDR)⁺ EPCs occurred at 24 h post-balloon inflation compared with the baseline level. The CD133^-/CD34⁺/KDR⁺ subpopulations showed undulating changes at 3, 7 and 24 h post-PCI (P=0.016, P=0.01 and P=0.032, respectively). An arch shape was displayed in CD133⁺/KDR⁺ cells; initially, a reduction occurred at 3 h and was maintained constantly until 7 h (P=0.003, P=0.013 and P=0.033 at 3, 5 and 7 h, respectively), after which a slight increase to the baseline level occurred at 24 h (P=0.084). The CD133⁺/CD34⁺ cells increased in stepwise manner until 24 h. The CD34⁺/KDR⁺ EPC change magnitude correlated significantly with a global damage index by partial correlation analysis (P<0.001). The results suggested that a time-dependent mobilization of EPCs may be initiated by PCI; the change magnitude of the CD34⁺/KDR⁺ cells was associated particularly with endothelial injury degree from the PCI procedure.

Association between microalbuminuria predicting in-stent restenosis after myocardial infarction and cellular senescence of endothelial progenitor cells

OBJECTIVE

Relationship between microalbuminuria and worse outcome of coronary artery disease patients is discussed, but its underlying pathophysiological mechanism remains unclear. We investigated the role of microalbuminuria to the function of endothelial progenitor cells (EPCs), that might affect to outcome of acute myocardial infarction (AMI) patients.

METHODS

Forty-five AMI patients were divided into two groups according to their urinary albumin excretion: normal (n = 24) and microalbuminuria (>30 mg/day, n = 21). At day-2 and day-7 after AMI onset, circulating-EPCs (CD34+ Flk1+) were quantified by flow cytometry. The number of lectin-acLDL-positive cultured-EPCs immobilized on fibronectin was determined. To assess the cellular senescence of cultured-EPCs, the expression level of sirtuin-1 mRNA and the number of SA-β-gal positive cell were evaluated. Angiographic late in-stent loss after percutaneous coronary intervention (PCI) was evaluated at a six-month follow-up.

RESULTS

No significant differences in coronary risk and the extent of myocardial damage were observed between the two groups. Late in-stent loss at the six-month follow-up was significantly higher in the microalbuminuria group (normal:microalbuminuria = 0.76±0.34:1.18±0.57 mm, p=0.021). The number of circulating-EPCs was significantly increased in microalbuminuria group at day-7, however, improved adhesion of EPCs was observed in normal group but not in microalbuminuria group from baseline to day-7 (+3.1±8.3:-1.3±4.4%: p<0.05). On the other hand, in microalbuminuria group at day-7, the level of sirtuin-1 mRNA expression of cultured-EPCs was significantly decreased (7.1±8.9:2.5±3.7 fold, p<0.05), which was based on the negative correlation between the level of sirtuin-1 mRNA expression and the extent of microalbuminuria. The ratio of SA-β-gal-positive cells in microalbuminuria group was increased compared to that of normal group.

CONCLUSIONS

Microalbuminuria in AMI patients is closely associated with functional disorder of EPCs via cellular senescence, that predicts the aggravation of coronary remodeling after PCI.

Ticagrelor increases endothelial progenitor cell level compared to clopidogrel in acute coronary syndromes: A prospective randomized study

BACKGROUND

The clinical benefit of ticagrelor compared to clopidogrel in ACS patients suggested off-target property. Such pleiotropic effect could be mediated by circulating endothelial progenitor cells (EPC) which are critical for vascular healing. We aimed to investigate the impact of ticagrelor on EPC in acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI).

METHODS

We prospectively randomized 106 ACS patients to ticagrelor or clopidogrel. Sub-populations of CD34+ circulating progenitor cells (PC) were analyzed by flow cytometry allowing one to determine the levels of CD34+ PC, CD34+CD45+ Hematopoietic PC, CD34+133+ immature PC and CD34+KDR+ EPC on admission and at 1 month. Changes in PC level were calculated as the difference between 1 month and baseline value.

RESULTS

The 2 groups were similar regarding baseline characteristics including PC numbers on admission. The 2 groups had similar change in overall CD34+ PC and hematopoietic CD34+45+ PC level (p=0.2). On the contrary, when considering CD34+133+ PC and CD34+KDR+ EPC, we observed that patients treated by ticagrelor had a significantly higher increase in levels of these PC subtypes compared to those treated by clopidogrel (0.23 (-0.33; 0.79) vs 0.00 (-0.5; 0.34); p=0.04 and 0.01 (-0.04; 0.05) vs -0.01 (-0.06; 0.03); p=0.02). Changes in the level of CD34+CD133+ PC correlated with platelet activity measured by the VASP index (r=-0.30; p=0.008). By contrast the increase in the level of CD34+KDR+ EPC in the ticagrelor group was independent of platelet activity.

CONCLUSIONS

Ticagrelor increases the number of EPC in ACS patients suggesting a benefit on endothelial regeneration that may participate in the pleiotropic property of the drug.

Circulating endothelial cells and progenitors as prognostic factors during autoimmune thrombotic thrombocytopenic purpura: results of a prospective multicenter French study

BACKGROUND

Autoimmune thrombotic thrombocytopenic purpura (AI-TTP) is characterized by an excess of circulating ultralarge von Willebrand factor (VWF) caused by anti-ADAMTS-13 autoantibodies. Animal studies, however, have shown that endothelial cell activation may also be an important trigger of AI-TTP.

OBJECTIVES

To prospectively study circulating biomarkers of endothelial lesion and activation, such as circulating endothelial cells (CECs), soluble P-selectin (sP-selectin), or VWF, and of endothelial repair, such as circulating progenitor cells (CPCs) and endothelial progenitor cells (EPCs), in AI-TTP, in relation to disease severity and prognosis.

RESULTS

Twenty-two patients were included in this study. CEC (P < 0.01), VWF (P < 0.05) and sP-selectin (P < 0.01) levels were significantly increased during crisis, and returned to baseline levels during remission. Both CEC (P < 0.05) and sP-selectin (P < 0.05) levels were significantly higher in patients who died or developed neurologic sequelae. CPC levels were substantially increased during the acute phase of the disease (P < 0.001), and returned to baseline levels during remission. Among CPCs, EPC levels were also increased during crisis (P < 0.05) and significantly decreased during remission. Patients who received < 16 plasma exchanges (PEs) had significantly higher EPC counts (P < 0.05) than those who needed more numerous PEs to obtain remission, suggesting that initial EPC counts may be associated with faster endothelial repair.

CONCLUSION

The profile of circulating endothelial markers shows massive endothelial activation and repair/remodeling during AI-TTP, and suggests that CECs and EPCs may be promising prognostic biomarkers of the disease.

Simvastatin attenuates TNF‑α‑induced apoptosis in endothelial progenitor cells via the upregulation of SIRT1

Endothelial progenitor cells (EPCs) originate from the bone marrow and can be classified as either early or late EPCs. The focus of this study was on late EPCs, as they play an important role in angiogenesis and vascular proliferation. Evidence suggests that inflammatory and oxidative changes can increase EPC apoptosis. Of note, tumor necrosis factor-α (TNF-α) is a contributing risk factor to the development of atherosclerosis and plays a key role as both an inflammatory mediator and an inducer of apoptosis in endothelial cells. Additionally, a member of the sirtuin family, silent information regulator type-1 (SIRT1), promotes cell survival by repressing p53- and non-p53-dependent apoptosis in response to DNA damage and oxidative stress. Statins have also been shown to play a key role in the prevention of endothelial apoptosis and senescence via their lipid-lowering and anti-inflammatory actions. However, there is little evidence that statins themselves attenuate EPC apoptosis induced by TNF-α. The aim of this study was to demonstrate the effectiveness of one of the most commonly used statins, simvastatin, on decreasing TNF-α-induced apoptosis in EPCs. The results indicated that SIRT1 protein expression was decreased by TNF-α in a time- and dose-dependent manner and that while TNF-α caused a marked increase in the percentage of apoptotic EPCs, application of simvastatin decreased this percentage. A high concentration of simvastatin promoted the expression of SIRT1 and increased the proliferation of EPCs. In conclusion, findings of this study showed that simvastatin is crucial in counteracting the TNF-α-induced apoptosis of EPCs and that this protection may involve the actions of SIRT1.

Relationship of depression, stress and endothelial function in stable angina patients

Endothelial dysfunction has been considered as one of potential mechanisms by which depression and stress might contribute to the development of coronary artery disease (CAD). Recent studies suggest that circulating endothelial progenitor cells (EPCs) and brachial artery flow-mediated dilation (FMD) are related to endothelial function and progression of CAD. We investigated the relationships between the level of circulating CD34/KDR(+) EPCs and CD133/KDR(+) EPCs, brachial FMD, and scores of depression and stress measured with the Depression Anxiety Stress Scales in 288 stable angina patients without major psychiatric disorders. As defined by the ≥75th percentile, 100 (35%) subjects had high depression score (≥8), and 84 (29%) subjects had high stress score (≥10). Subjects with high depression or stress score had significantly lower FMD (1.86±0.14 vs. 3.63±0.17%, p<0.001; 2.05±0.18 vs. 3.48±0.17%, p<0.001) and percentage of circulating CD34/KDR(+) EPCs (0.97±0.11 vs. 1.94±0.17%, p<0.001; 1.09±0.13 vs. 1.68±0.16%, p=0.005), but not CD133/KDR(+) EPCs (0.52±0.04 vs. 0.66±0.06%, p=0.057; 0.61±0.05 vs. 0.59±0.05%, p=0.833), as compared with subjects with normal depression or stress score. Multivariate regression analysis indicated that high depression score (OR 1.09, 95% CI: 1.04-1.15, p<0.001), but not stress score or percentage of circulating EPCs, independently predicted impaired brachial FMD. In conclusions, our results demonstrated that in stable angina patients without major psychiatric disorders, a high depression or stress score was related to attenuated brachial FMD and depletion of circulating EPCs. However, only the depression score, but not the stress score or the level of EPCs, was an independent predictor for decreased brachial FMD.