Circulating Progenitor Cells and Racial Differences

Circulating Progenitor Cells and Coronary Collaterals in Chronic Total Occlusion

BACKGROUND

The role of circulating progenitor cells (CPC) in collateral formation that occurs in the presence of chronic total occlusions (CTO) of a coronary artery is not well established. In stable patients with a CTO, we investigated whether CPC levels are associated with (a) collateral development and (b) ischemic burden, as measured by circulating high sensitivity troponin-I (hsTn-I) levels.

METHODS

CPCs were enumerated by flow cytometry as CD45med+ blood mononuclear cells expressing CD34 and both CD34 and CD133 epitopes. The association between CPC counts and both Rentrop collateral grade (0, 1, 2, or 3) and hsTn-I levels were evaluated using multivariate regression analysis, after adjusting for demographic and clinical characteristics.

RESULTS

In 89 patients (age 65.5, 72% male, 27% Black), a higher CPC count was positively associated with a higher Rentrop collateral grade; [CD34+ adjusted odds ratio (OR) 1.49 95% confidence interval (CI) (0.95, 2.34) P = 0.082] and [CD34+/CD133+ OR 1.57 95% CI (1.05, 2.36) P = 0.028]. Every doubling of CPC counts was also associated with lower hsTn-I levels [CD34+ β -0.35 95% CI (-0.49, -0.15) P = 0.002] and [CD34+/CD133+ β -0.27 95% CI (-0.43, -0.08) P = 0.009] after adjustment.

CONCLUSION

Individuals with higher CPC counts have greater collateral development and lower ischemic burden in the presence of a CTO.

Vascular Regenerative Cell Deficiencies in South Asian Adults

BACKGROUND

South Asian individuals shoulder a disproportionate burden of cardiometabolic diseases.

OBJECTIVES

The purpose of this study was to determine if vascular regenerative cell content varies significantly between South Asian and White European people.

METHODS

Between January 2022 and January 2023, 60 South Asian and 60 White European adults with either documented cardiovascular disease or established diabetes with ≥1 other cardiovascular risk factor were prospectively enrolled. Vascular regenerative cell content in venous blood was enumerated using a flow cytometry assay that is based on high aldehyde dehydrogenase (ALDHhi) activity and cell surface marker phenotyping. The primary outcome was the difference in frequency of circulating ALDHhi progenitor cells, monocytes, and granulocytes between the 2 groups.

RESULTS

Compared with White European participants, those of South Asian ethnicity were younger (69 ± 10 years vs 66 ± 9 years; P < 0.05), had lower weight (88 ± 19 kg vs 75 ± 13 kg; P < 0.001), and exhibited a greater prevalence of type 2 diabetes (62% vs 92%). South Asian individuals had markedly lower circulating frequencies of pro-angiogenic ALDHhiSSClowCD133+ progenitor cells (P < 0.001) and ALDHhiSSCmidCD14+CD163+ monocytes with vessel-reparative capacity (P < 0.001), as well as proportionally more ALDHhi progenitor cells with high reactive oxygen species content (P < 0.05). After correction for sex, age, body mass index, and glycated hemoglobin, South Asian ethnicity was independently associated with lower ALDHhiSSClowCD133+ cell count.

CONCLUSIONS

South Asian people with cardiometabolic disease had less vascular regenerative and reparative cells suggesting compromised vessel repair capabilities that may contribute to the excess vascular risk in this population. (The Role of South Asian vs European Origins on Circulating Regenerative Cell Exhaustion [ORIGINS-RCE]; NCT05253521).

Tankyrase Inhibition Attenuates Cardiac Dilatation and Dysfunction in Ischemic Heart Failure

Hyperactive poly(ADP-ribose) polymerases (PARP) promote ischemic heart failure (IHF) after myocardial infarction (MI). However, the role of tankyrases (TNKSs), members of the PARP family, in pathogenesis of IHF remains unknown. We investigated the expression and activation of TNKSs in myocardium of IHF patients and MI rats. We explored the cardioprotective effect of TNKS inhibition in an isoproterenol-induced zebrafish HF model. In IHF patients, we observed elevated TNKS2 and DICER and concomitant upregulation of miR-34a-5p and miR-21-5p in non-infarcted myocardium. In a rat MI model, we found augmented TNKS2 and DICER in the border and infarct areas at the early stage of post-MI. We also observed consistently increased TNKS1 in the border and infarct areas and destabilized AXIN in the infarct area from 4 weeks onward, which in turn triggered Wnt/β-catenin signaling. In an isoproterenol-induced HF zebrafish model, inhibition of TNKS activity with XAV939, a TNKSs-specific inhibitor, protected against ventricular dilatation and cardiac dysfunction and abrogated overactivation of Wnt/β-catenin signaling and dysregulation of miR-34a-5p induced by isoproterenol. Our study unravels a potential role of TNKSs in the pathogenesis of IHF by regulating Wnt/β-catenin signaling and possibly modulating miRNAs and highlights the pharmacotherapeutic potential of TNKS inhibition for prevention of IHF.

The innate immune response following multivalent dengue vaccination and implications for protection against dengue challenge

Understanding the immune response to dengue virus (DENV) is essential for developing a dengue vaccine that is protective against all 4 DENV serotypes. We evaluated the immune response after vaccination (live attenuated tetravalent dengue vaccine TV005 or trivalent admixture) and after challenge with DEN2Δ30 (Tonga/74) to better understand the importance of homotypic immunity in vaccine protection. Significant increases in IP-10 expression were observed following receipt of either the trivalent or tetravalent vaccine. After challenge, a large increase in IP-10 expression was observed in the placebo and trivalent admixture groups but not in the tetravalent vaccine group. MCP-1, IL-1RA, and MIP-1β exhibited a similar pattern as IP-10. These results demonstrate protective effects of trivalent and tetravalent vaccines against DENV and suggest that the tetravalent vaccine has a better protective effect compared with the trivalent admixture. We also explored the postvaccination and postchallenge immune response differences between Black and White participants. White participants responded to vaccine differently than Black participants; Black participants receiving trivalent and tetravalent vaccines responded strongly and White participants responded only transiently in trivalent group. In response to challenge, White participants elicited a stronger response than Black participants. These results may explain why White participants may have a more vigorous DENV immune response than Black participants, as reported in literature.

Endothelial Progenitor Cells in Coronary Artery Disease: From Bench to Bedside

Endothelial progenitor cells (EPCs) are a heterogeneous group of cells present in peripheral blood at various stages of endothelial differentiation. EPCs have been extensively investigated in patients with coronary artery disease (CAD), with controversial findings both on their role in atherosclerosis progression and in the process of neointimal growth after a percutaneous coronary intervention (PCI). Despite nearly 2 decades of experimental and clinical investigations, however, the significance of EPCs in clinical practice remains unclear and poorly understood. This review provides an update on the role of EPCs in the most common clinical scenarios that are experienced by cardiologists managing patients with CAD. We here summarize the main findings on the association of EPCs with cardiovascular risk factors, coronary atherosclerosis, and myocardial ischemia. We then discuss the potential effects of EPCs in post-PCI in-stent restenosis, as well as most recent findings with EPC-coated stents. Based on the mounting evidence of the relationship between levels of EPCs and several different adverse cardiovascular events, EPCs are emerging as novel predictive biomarkers of long-term outcomes in patients with CAD.

The impact of different forms of exercise on endothelial progenitor cells in healthy populations

Circulating endothelial progenitor cells (EPCs) contribute to vascular healing and neovascularisation, while exercise is an effective means to mobilise EPCs into the circulation.

OBJECTIVES

to systematically examine the acute and chronic effects of different forms of exercise on circulating EPCs in healthy populations.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines were followed.

RESULTS

thirty-one articles met the inclusion criteria including 747 participants aged 19 to 76 years. All included trials used flow cytometry for identification of circulating EPCs. Eight and five different EPC phenotypes were identified in the acute and chronic trials, respectively. In the acute trials, moderate intensity continuous (MICON), maximal, prolonged endurance, resistance and high intensity interval training (HIIT) exercise protocols were utilised. Prolonged endurance and resistance exercise had the most profound effect on circulating EPCs followed by maximal exercise. In the chronic trials, MICON exercise, HIIT, HIIT compared to MICON and MICON compared to exergame (exercise modality based on an interactive video game) were identified. MICON exercise had a positive effect on circulating EPCs in older sedentary individuals which was accompanied by improvements in endothelial function and arterial stiffness. Long-stage HIIT (4 min bouts) appears to be an effective means and superior than MICON exercise in mobilising circulating EPCs. In conclusion, both in acute and chronic trials the degree of exercise-induced EPC mobilisation depends upon the exercise regime applied. In future, more research is warranted to examine the dose-response relationship of different exercise forms on circulating EPCs using standardised methodology and EPC phenotype.

Environmental exposure to volatile organic compounds is associated with endothelial injury

OBJECTIVE

Volatile organic compounds (VOCs) are airborne toxicants abundant in outdoor and indoor air. High levels of VOCs are also present at various Superfund and other hazardous waste sites; however, little is known about the cardiovascular effects of VOCs. We hypothesized that ambient exposure to VOCs exacerbate cardiovascular disease (CVD) risk by depleting circulating angiogenic cells (CACs).

APPROACH AND RESULTS

In this cross-sectional study, we recruited 603 participants with low-to-high CVD risk and measured 15 subpopulations of CACs by flow cytometry and 16 urinary metabolites of 12 VOCs by LC/MS/MS. Associations between CAC and VOC metabolite levels were examined using generalized linear models in the total sample, and separately in non-smokers. In single pollutant models, metabolites of ethylbenzene/styrene and xylene, were negatively associated with CAC levels in both the total sample, and in non-smokers. The metabolite of acrylonitrile was negatively associated with CD45^dim/CD146⁺/CD34⁺/AC133⁺ cells and CD45⁺/CD146⁺/AC133⁺, and the toluene metabolite with AC133⁺ cells. In analysis of non-smokers (n = 375), multipollutant models showed a negative association with metabolites of ethylbenzene/styrene, benzene, and xylene with CD45^dim/CD146⁺/CD34⁺ cells, independent of other VOC metabolite levels. Cumulative VOC risk score showed a strong negative association with CD45^dim/CD146⁺/CD34⁺ cells, suggesting that total VOC exposure has a cumulative effect on pro-angiogenic cells. We found a non-linear relationship for benzene, which showed an increase in CAC levels at low, but depletion at higher levels of exposure. Sex and race, hypertension, and diabetes significantly modified VOC associated CAC depletion.

CONCLUSION

Low-level ambient exposure to VOCs is associated with CAC depletion, which could compromise endothelial repair and angiogenesis, and exacerbate CVD risk.

Circulating Progenitor Cells and Cognitive Impairment in Men and Women with Coronary Artery Disease

BACKGROUND

Circulating progenitor cells (CPC) have been associated with memory function and cognitive impairment in healthy adults. However, it is unclear whether such associations also exist in patients with coronary artery disease (CAD).

OBJECTIVE

To assess the association between CPCs and memory performance among individuals with CAD.

METHODS

We assessed cognitive function in 509 patients with CAD using the verbal and visual Memory subtests of the Wechsler memory scale-IV and the Trail Making Test parts A and B. CPCs were enumerated with flow cytometry as CD45med/CD34+ blood mononuclear cells, those co-expressing other epitopes representing populations enriched for hematopoietic and endothelial progenitors.

RESULTS

After adjusting for demographic and cardiovascular risk factors, lower number of endothelial progenitor cell counts were independently associated with lower visual and verbal memory scores (p for all < 0.05). There was a significant interaction in the magnitude of this association with race (p < 0.01), such that the association of verbal memory scores with endothelial progenitor subsets was present in Black but not in non-Black participants. No associations were present with the hematopoietic progenitor-enriched cells or with the Trail Making Tests.

CONCLUSION

Lower numbers of circulating endothelial progenitor cells are associated with cognitive impairment in patients with CAD, suggesting a protective effect of repair/regeneration processes in the maintenance of cognitive status. Impairment of verbal memory function was more strongly associated with lower CPC counts in Black compared to non-Black participants with CAD. Whether strategies designed to improve regenerative capacity will improve cognition needs further study.

Sex-Based Differences in Autologous Cell Therapy Trials in Patients With Acute Myocardial Infarction: Subanalysis of the ACCRUE Database

Background: Sex-based differences are under-studied in cardiovascular trials as women are commonly underrepresented in dual sex studies, even though major sex-based differences in epidemiology, pathophysiology, and outcomes of cardiovascular disease have been reported. We examined sex-based differences in patient characteristics, outcome, and BM-CD34+ frequency of the ACCRUE (Meta-Analysis of Cell-based CaRdiac studies) database involving patients with acute myocardial infarction (AMI) randomized to autologous cell-based or control treatment. Methods: We compared baseline characteristics and 1-year follow-up clinical data: composite major adverse cardiac and cerebrovascular events (primary endpoint), and changes in left ventricular ejection fraction (LVEF), end-diastolic (EDV), and end-systolic volumes (ESV) (secondary efficacy endpoint) in women and men (N = 1,252; 81.4% men). Secondary safety endpoints included freedom from hard clinical endpoints. Results: In cell-treated groups, women but not men had a lower frequency of stroke, AMI, and mortality than controls. The frequency of BM-CD34+ cells was significantly correlated with baseline EDV and ESV and negatively correlated with baseline LVEF in both sexes; a left shift in regression curve in women indicated a smaller EDV and ESV was associated with higher BM-CD34+ cells in women. Conclusions: Sex differences were found in baseline cardiovascular risk factors and cardiac function and in outcome responses to cell therapy.

Association Between Change in Circulating Progenitor Cells During Exercise Stress and Risk of Adverse Cardiovascular Events in Patients With Coronary Artery Disease

Importance

Stem and progenitor cells mobilize from the bone marrow in response to myocardial ischemia. However, the association between the change in circulating progenitor cell (CPC) counts and disease prognosis among patients with ischemia is unknown.

Objective

To investigate the association between the change in CPC counts during stress testing and the risk of adverse cardiovascular events in patients with stable coronary artery disease (CAD).

Design, Setting, and Participants

This prospective cohort study included a population-based sample of 454 patients with stable CAD who were recruited between June 1, 2011, and August 15, 2014, at Emory University-affiliated hospitals and followed up for 3 years. Data were analyzed from September 15, 2018, to October 15, 2018.

Exposures

Myocardial perfusion imaging with technetium Tc 99m sestamibi at rest and 30 to 60 minutes after conventional stress testing.

Main Outcomes and Measures

Circulating progenitor cells were enumerated with flow cytometry as CD34-expressing mononuclear cells (CD45med/CD34+), with additional quantification of subsets coexpressing the chemokine (C-X-C motif) receptor 4 (CD34+/CXCR4+). Changes in CPC counts were calculated as poststress minus resting CPC counts. Cox proportional hazards regression models were used to identify factors associated with the combined end point of cardiovascular death and myocardial infarction after adjusting for clinical covariates, including age, sex, race, smoking history, body mass index, and history of heart failure, hypertension, dyslipidemia, and diabetes.

Results

Of the 454 patients (mean [SD] age, 63 [9] years; 76% men) with stable CAD enrolled in the study, 142 (31.3%) had stress-induced ischemia and 312 (68.7%) did not, as measured by single-photon emission computed tomography. During stress testing, patients with stress-induced ischemia had a mean decrease of 20.2% (interquartile range [IQR], -45.3 to 5.5; P < .001) in their CD34+/CXCR4+ counts, and patients without stress-induced ischemia had a mean increase of 3.2% (IQR, -20.6 to 35.1; P < .001) in their CD34+/CXCR4+ counts. Twenty-four patients (5.2%) experienced adverse events. After adjustment, baseline CPC counts were associated with worse adverse outcomes, but this association was not present after stress-induced ischemia was included in the model. However, the change in CPC counts during exercise remained significantly associated with adverse events (hazard ratio, 2.59; 95% CI, 1.15-5.32, per 50% CD34+/CXCR4+ count decrease), even after adjustment for clinical variables and the presence of ischemia. The discrimination of risk factors associated with incident adverse events improved (increase in C statistic from 0.72 to 0.77; P = .003) with the addition of the change in CD34+/CXCR4+ counts to a model that included clinical characteristics, baseline CPC count, and ischemia.

Conclusions and Relevance

In this study of patients with CAD, a decrease in CPC counts during exercise is associated with a worse disease prognosis compared with the presence of stress-induced myocardial ischemia. Further studies are needed to evaluate whether strategies to improve CPC responses during exercise stress will be associated with improvements in the prognosis of patients with CAD.

Estimating cell-type-specific DNA methylation effects in heterogeneous cellular populations

Aim: To develop a method for estimating cell-specific effects in epigenomic association studies in the presence of cell type heterogeneity. Materials & methods: We utilized Monte Carlo Expectation-Maximization algorithm with Metropolis-Hastings sampler to reconstruct the 'missing' cell-specific methylations and to estimate their associations with phenotypes free of confounding by cell type proportions. Results: Simulations showed reliable performance of the method under various settings including when the cell type is rare. Application to a real dataset recapitulated the directly measured cell-specific methylation pattern in whole blood. Conclusion: This work provides a framework to identify important cell groups and account for cell type composition useful for studying the role of epigenetic changes in human traits and diseases.

Endothelial progenitor cell transplantation restores vascular injury in mice after whole-brain irradiation

Vascular damage plays an important role in the pathogenesis of radiation-induced brain injury (RBI). Endothelial progenitor cells (EPCs) are responsible for maintaining and repairing endothelial function, and have become a promising method for the treatment of cerebrovascular diseases. However, whether EPC transplantation plays a protective role in RBI has not been fully elucidated. Therefore, the present study investigated the effects of bone marrow-derived EPC transplantation in a whole-brain irradiation (WBI) mouse model. Mice were divided into the three groups: control group, irradiation group and EPCs group. Phosphate buffered saline or EPCs were intravenously injected into mice one week after irradiation, and brains were analyzed eight weeks after injection. Flow cytometry demonstrated that irradiation led to a significant reduction in the peripheral blood EPC count; however, EPC transplantation led to a significant increase in the circulating EPCs. Intravital two-photon imaging and western blotting demonstrated that EPC transplantation reversed the effects of irradiation by decreasing blood-brain barrier permeability and increasing the expression of tight junction proteins in the brain. Additionally, immunofluorescence staining revealed that the brain microvascular density was higher in the EPCs group than the irradiation group. Therefore, EPC transplantation may restore damage caused by WBI to the blood-brain barrier, tight junctions, and cerebral capillary density. These results highlight the potential beneficial effects of EPC transplantation on vascular damage induced by RBI.

Racial Differences in the Effect of Granulocyte Macrophage Colony-Stimulating Factor on Improved Walking Distance in Peripheral Artery Disease: The PROPEL Randomized Clinical Trial

Background The effects of race on response to medical therapy in people with peripheral artery disease ( PAD ) are unknown. Methods and Results In the PROPEL (Progenitor Cell Release Plus Exercise to Improve Functional Performance in PAD) Trial, PAD participants were randomized to 1 of 4 groups for 6 months: supervised treadmill exercise+granulocyte-macrophage colony-stimulating factor ( GM - CSF ) (Group 1), exercise+placebo (Group 2), attention control+ GM - CSF (Group 3), or attention control+placebo (Group 4). Change in 6-minute walk distance was measured at 12- and 26-week follow-up. In these exploratory analyses, groups receiving GM - CSF (Groups 1 and 3), placebo (Groups 2 and 4), exercise (Groups 1 and 2), and attention control (Groups 2 and 4) were combined, maximizing statistical power for studying the effects of race on response to interventions. Of 210 PAD participants, 141 (67%) were black and 64 (30%) were white. Among whites, GM - CSF improved 6-minute walk distance by +22.0 m (95% CI : -4.5, +48.5, P=0.103) at 12 weeks and +44.4 m (95% CI : +6.9, +82.0, P=0.020) at 26 weeks, compared with placebo. Among black participants, there was no effect of GM - CSF on 6-minute walk distance at 12-week ( P=0.26) or 26-week (-5.0 m [-27.5, +17.5, P=0.66]) follow-up, compared with placebo. There was an interaction of race on the effect of GM - CSF on 6-minute walk change at 26-week follow-up ( P=0.018). Exercise improved 6-minute walk distance in black ( P=0.006) and white ( P=0.034) participants without interaction. Conclusions GM - CSF improved 6-minute walk distance in whites with PAD but had no effect in black participants. Further study is needed to confirm racial differences in GM - CSF efficacy in PAD . Clinical Trial Registration URL : http://www.clinicaltrials.gov . Unique identifier: NCT 01408901.