The dynamics of the coronary collateral circulation

Transcoronary Gradients of Mechanosensitive MicroRNAs as Predictors of Collateral Development in Chronic Total Occlusion

Background and Objectives: In this present study, we investigated the impact of mechanosensitive microRNAs (mechano-miRs) on the collateral development in 126 chronic total occlusion (CTO) patients, selected from 810 undergoing angiography. Materials and Methods: We quantified the collateral blood supply using the collateral flow index (CFI) and assessed the transcoronary mechano-miR gradients. Results: The patients with favorable collaterals had higher CFI values (0.45 ± 0.02) than those with poor collaterals (0.38 ± 0.03, p < 0.001). Significant differences in transcoronary gradients were found for miR-10a, miR-19a, miR-21, miR-23b, miR-26a, miR-92a, miR-126, miR-130a, miR-663, and let7d (p < 0.05). miR-26a and miR-21 showed strong positive correlations with the CFI (r = 0.715 and r = 0.663, respectively), while let7d and miR-663 were negatively correlated (r = -0.684 and r = -0.604, respectively). The correlations between cytokine gradients and mechano-miR gradients were also significant, including Transforming Growth Factor Beta with miR-126 (r = 0.673, p < 0.001) and Vascular Endothelial Growth Factor with miR-10a (r = 0.602, p = 0.002). A regression analysis highlighted the hemoglobin level, smoking, beta-blocker use, miR-26a, and miR-663 as significant CFI determinants, indicating their roles in modulating the collateral vessel development. Conclusions: These findings suggest mechanosensitive microRNAs as predictive biomarkers for collateral circulation, offering new therapeutic perspectives for CTO patients.

Promoting collateral formation in type 2 diabetes mellitus using ultra-small nanodots with autophagy activation and ROS scavenging

BACKGROUND

Impaired collateral formation is a major factor contributing to poor prognosis in type 2 diabetes mellitus (T2DM) patients with atherosclerotic cardiovascular disease. However, the current pharmacological treatments for improving collateral formation remain unsatisfactory. The induction of endothelial autophagy and the elimination of reactive oxygen species (ROS) represent potential therapeutic targets for enhancing endothelial angiogenesis and facilitating collateral formation. This study investigates the potential of molybdenum disulfide nanodots (MoS2 NDs) for enhancing collateral formation and improving prognosis.

RESULTS

Our study shows that MoS2 NDs significantly enhance collateral formation in ischemic tissues of diabetic mice, improving effective blood resupply. Additionally, MoS2 NDs boost the proliferation, migration, and tube formation of endothelial cells under high glucose/hypoxia conditions in vitro. Mechanistically, the beneficial effects of MoS2 NDs on collateral formation not only depend on their known scavenging properties of ROS (H2O2, •O2-, and •OH) but also primarily involve a molecular pathway, cAMP/PKA-NR4A2, which promotes autophagy and contributes to mitigating damage in diabetic endothelial cells.

CONCLUSIONS

Overall, this study investigated the specific mechanism by which MoS2 NDs mediated autophagy activation and highlighted the synergy between autophagy activation and antioxidation, thus suggesting that an economic and biocompatible nano-agent with dual therapeutic functions is highly preferable for promoting collateral formation in a diabetic context, thus, highlighting their therapeutic potential.

Circulating secretoneurin level reflects angiographic coronary collateralization in stable angina patients with chronic total occlusion

OBJECTIVE

To investigate the association between circulating secretoneurin (SN) and angiographic coronary collateralization in stable angina patients with chronic coronary total occlusion (CTO).

METHODS

SN concentrations in serum were measured in 641 stable angina patients with CTO by radioimmunoassay. The status of coronary collaterals from the contra-lateral vessel was visually estimated using the Rentrop grading system, and was categorized into poor (grade 0 or 1) or good (grade 2 or 3) collateralization.

RESULTS

Serum SN levels were significantly higher in patients with good coronary collaterals compared to those with poor collaterals (175.23 ± 52.09 pmol/L vs. 143.29 ± 42.01 pmol/L, P < 0.001). Serum SN increased stepwise across Rentrop score 0 to 3 (P < 0.001), and increasing SN tertiles were associated with higher proportion of good coronary collateralization (OR, 1.907; 95% CI, 1.558 ~ 2.335, P < 0.001). After adjustment for confounding variables, serum SN (per tertile) remained an independent factor for predicting good coronary collaterals (OR, 1.870; 95% CI, 1.515 ~ 2.309; P < 0.001). Moreover, the diagnostic value of serum SN (per tertile) was consistent after stratifying patients based on gender, age, body mass index, hypertension, diabetes, history of smoking, severity of coronary artery disease and kidney function (OR: 1.511 ~ 2.680, P interaction ≥ 0.327).

CONCLUSION

Elevated circulating SN reflects good angiographic coronary collaterals in stable angina patients with CTO. The findings may provide insight into decision-making for these patients.

Increased Plasma Non-High-Density Lipoprotein Levels and Poor Coronary Collateral Circulation in Patients With Stable Coronary Artery Disease

BACKGROUND

This study investigated the relationship between coronary collateral circulation (CCC) and non-high-density lipoprotein cholesterol (non-HDL-C) in patients with stable coronary artery disease (CAD). Coronary collateral circulation plays a critical role in supporting blood flow, particularly in the ischemic myocardium. Previous studies show that non-HDL-C plays a more important role in the formation and progression of atherosclerosis than do standard lipid parameters.

METHODS

A total of 226 patients with stable CAD and stenosis of more than 95% in at least 1 epicardial coronary artery were included in the study. Rentrop classification was used to assign patients into group 1 (n = 85; poor collateral) or 2 (n = 141; good collateral). To adjust for the observed imbalance in baseline covariates between study groups, propensity-score matching was used. Covariates were diabetes, Gensini score, and angiotensin-converting enzyme inhibitor use.

RESULTS

In the propensity-matched population, the plasma non-HDL-C level (mean [SD], 177.86 [44.0] mg/dL vs 155.6 [46.21] mg/dL; P = .001) was statistically higher in the poor-collateral group. LDL-C (odds ratio [OR], 1.23; 95% CI, 1.11-1.30; P = .01), non-HDL-C (OR, 1.34; 95% CI, 1.20-1.51; P = .01), C-reactive protein (OR, 1.21; 95% CI, 1.11-1.32; P = .03), systemic immune-inflammation index (OR, 1.14; 95% CI, 1.05-1.21; P = .01), and C-reactive protein to albumin ratio (OR, 1.11; 95% CI, 1.06-1.17; P = .01) remained independent predictors of CCC in multivariate logistic regression analysis.

CONCLUSION

Non-HDL-C was an independent risk factor for developing poor CCC in stable CAD.

Association between myocardial ischemia and plaque characteristics in chronic total occlusion

BACKGROUND

Myocardial ischemia varies in chronic total occlusion (CTO) despite the occluded artery. We analyzed whether it is associated with the plaque characteristics of the occluded segment.

METHODS

We retrospectively enrolled 100 patients with CTO who underwent myocardial perfusion single-photon emission computed tomography (SPECT) and coronary computed tomography angiography (CCTA) within 2 months. CTO-related ischemia was classified as moderate to severe (summed difference score [SDS] of the CTO territory ≥ 5) or mild or none (SDS < 5) on SPECT. Using CCTA, the atherosclerotic plaques of the occluded segment were subdivided into low-density (- 100-30 HU), intermediate-density (31-350 HU), and high-density (351-1000 HU) plaques. The plaque composition was compared according to the severity of CTO-related ischemia.

RESULTS

Moderate-to-severe CTO-related ischemia (n = 23) showed significantly higher proportion of intermediate-density plaques (72.4% vs. 64.0%), intermediate/low-density (7.10 vs. 3.65) and intermediate-to-high/low-density (7.78 vs. 3.80) plaque ratios, frequent shorter occlusion (30% vs. 6%), and lower volume (26.5 mm3 vs. 58.8 mm3) and proportion (11.4% vs. 20.8%) of low-density plaques. Multivariable analysis revealed significant associations between higher proportion of intermediate-density plaques and moderate-to-severe CTO-related ischemia, independent of occlusion length.

CONCLUSION

Higher proportion of intermediate-density plaques in the occluded segment was associated with the moderate-to-severe CTO-related ischemia.

The Effects of Exercise on Coronary Collateral Circulation: A Review

The effects of exercise on the cardiovascular system are multifaceted and complex. It is well-documented that exercise can reduce mortality related to cardiovascular pathology. One anatomical structure that has been implicated in this process is the coronary collateral circulation. The goal of this review is to evaluate the current literature on the effects of exercise on human coronary collateral circulation. A search for literature was conducted on the databases Science Direct and PubMed using the terms: coronary collateral, collateral, exercise, physical activity, resistance training, endurance training, and collateral artery. Research that had the primary outcome of assessing human coronary collateralization secondary to exercise was included. Research in which the effect of exercise was not the primary outcome was excluded. As a result, a total of 13 research papers on the effects of exercise on coronary collateral circulation were included. Thirteen original research papers were reviewed. The mean age range in all studies was between 48 and 64 years old. There was a predominance of male participants, with a total of 597 male patients and 108 female patients across all studies. It was found that initial research underestimated the effect of exercise on coronary collateral circulation due to a lack of sensitive assessment methods. With the introduction of sensitive measures like the collateral flow index (CFI) and Rentrop scoring, results have shown that coronary collateral function can be increased with exercise. Exercise has been shown to enhance coronary collateral function. There is limited evidence as to which type, duration, or intensity of exercise is most favourable to enhance coronary collateral function. There is also relatively little data on the effects of exercise in the female population and those over the age of 65 years. More research is required to determine the specific effects of exercise on coronary collateral circulation in various age groups, genders, co-morbidities, specific exercise modalities, durations, intensities, and the effect of pharmacotherapy.

LncRNA PVT1 is a novel mediator promoting the angiogenesis response associated with collateral artery formation

AIMS

Angiogenesis plays a key role in coronary collateral circulation (CCC), the compensatory formation of new blood vessels during chronic total coronary occlusion. This study aimed to determine whether plasmacytoma variant translocation 1 (PVT1), a long non-coding (lnc) RNA involved in tumor angiogenesis, plays a role in regulating angiogenesis during chronic coronary ischemia.

MAIN METHODS

Patients with coronary artery disease, and ≥90% stenosis, were examined and divided into "Good" and "Poor" CCC groups based on Rentrop Cohen classification. RNA samples were obtained from all patients, as well as from oxygen and glucose-deprived (OGD) HUVECs. PVT1, miR-15b-5p and AKT3 levels were measured with RT-qPCR or Western blot, while HUVEC migration and angiogenesis were detected by, respectively, wound-healing and tube formation assays. Luciferase reporter assay confirmed direct PVT1-miR-15b-5p binding.

KEY FINDINGS

Increased PVT1 was found in "Good CCC" patient plasma, along with being highly expressed among OGD HUVECs; PVT1 knockdown reduced HUVEC migration, tube formation, and pro-angiogenic factor expression. Conversely, OGD HUVECs had downregulated miR-15b-5p, and miR-15b-5p overexpression significantly depressed their angiogenic capabilities. These PVT1 knockdown- or miR-15b-5p overexpression-associated reductions in angiogenic effects were reversed by AKT3 overexpression. In vivo, neovascularization and functioning in both ischemic mice hind-limbs and infarcted myocardium injected with ADV-sh-PVT1 were reduced, which were ameliorated by concurrent antagomiR-15b-5p injections.

SIGNIFICANCE

Circulating PVT1 may serve as a useful biomarker to distinguish between good versus poor CCC, as it is involved in orchestrating angiogenesis via the miR-15b-5p-AKT3 axis; it thus has potential as a target for treating ischemic disease.

Diabetic dyslipidemia impairs coronary collateral formation: An update

Coronary collateralization is substantially impaired in patients with type 2 diabetes and occlusive coronary artery disease, which leads to aggravated myocardial ischemia and a more dismal prognosis. In a diabetic setting, altered serum lipid profiles and profound glycoxidative modification of lipoprotein particles induce endothelial dysfunction, blunt endothelial progenitor cell response, and severely hamper growth and maturation of collateral vessels. The impact of dyslipidemia and lipid-lowering treatments on coronary collateral formation has become a topic of heightened interest. In this review, we summarized the association of triglyceride-based integrative indexes, hypercholesterolemia, increased Lp(a) with its glycoxidative modification, as well as quantity and quality abnormalities of high-density lipoprotein with impaired collateral formation. We also analyzed the influence of innovative lipid-modifying strategies on coronary collateral development. Therefore, clinical management of diabetic dyslipidemia should take into account of its effect on coronary collateralization in patients with occlusive coronary artery disease.

Blood flow modeling reveals improved collateral artery performance during the regenerative period in mammalian hearts

Collateral arteries bridge opposing artery branches, forming a natural bypass that can deliver blood flow downstream of an occlusion. Inducing coronary collateral arteries could treat cardiac ischemia, but more knowledge on their developmental mechanisms and functional capabilities is required. Here we used whole-organ imaging and three-dimensional computational fluid dynamics modeling to define spatial architecture and predict blood flow through collaterals in neonate and adult mouse hearts. Neonate collaterals were more numerous, larger in diameter and more effective at restoring blood flow. Decreased blood flow restoration in adults arose because during postnatal growth coronary arteries expanded by adding branches rather than increasing diameters, altering pressure distributions. In humans, adult hearts with total coronary occlusions averaged 2 large collaterals, with predicted moderate function, while normal fetal hearts showed over 40 collaterals, likely too small to be functionally relevant. Thus, we quantify the functional impact of collateral arteries during heart regeneration and repair-a critical step toward realizing their therapeutic potential.

Cytokine storm: behind the scenes of the collateral circulation after acute myocardial infarction

At least 17 million people die from acute myocardial infarction (AMI) every year, ranking it first among causes of death of human beings, and its incidence is gradually increasing. Typical characteristics of AMI include acute onset and poor prognosis. At present, there is no satisfactory treatment, but development of coronary collateral circulation (CCC) can be key to improving prognosis. Recent research indicates that the levels of cytokines, including those related to promoting inflammatory responses and angiogenesis, increase after the onset of AMI. In the early phase of AMI, cytokines play a vital role in inducing development of collateral circulation. However, when myocardial infarction is decompensated, cytokine secretion increases greatly, which may induce a cytokine storm and worsen prognosis. Cytokines can regulate the activation of a variety of signal pathways and form a complex network, which may promote or inhibit the establishment of collateral circulation. We searched for published articles in PubMed and Google Scholar, employing the keyword “acute myocardial infarction”, “coronary collateral circulation” and “cytokine storm”, to clarify the relationship between AMI and a cytokine storm, and how a cytokine storm affects the growth of collateral circulation after AMI, so as to explore treatment methods based on cytokine agents or inhibitors used to improve prognosis of AMI.

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.

Integrated Analysis of Angiogenesis Related lncRNA-miRNA-mRNA in Patients With Coronary Chronic Total Occlusion Disease

Background: Coronary chronic total occlusion (CTO) disease is common and its specific characteristic is collateral formation. The Integrated analysis of angiogenesis related lncRNA-miRNA-mRNA network remains unclear and might provide target for future studies.

Methods: A total of five coronary artery disease (control group) and five CTO (CTO group) patients were selected for deep RNA and miRNA sequencing. The expression profiles of lncRNAs, mRNAs circRNA and miRNAs were obtained. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were then performed. The expression of a 14q32 miRNA gene cluster, including miRNA-494, miRNA-495 and miRNA-329, were selected to be determined in another larger patient cohort. Analysis of the lncRNA-miRNA495-mRNA network was constructed to find potential targets for future studies.

Results: A total of 871 lncRNAs, 1,080 mRNAs, 138 circRNAs and 56 miRNAs were determined as differentially expressed (DE) in CTO patients compared with control patients. GO and KEGG analyses revealed that the top terms included MAPK signaling pathway, HIF-1 signaling pathway, EGFR tyrosine kinase inhibitor resistance, embryonic organ development, wound healing, MAPK signaling pathway and JAK-STAT signaling pathway, which are related to angiogenesis. The expression of miRNA-494, miRNA-495 and miRNA-329 were all significantly down-regulated in CTO patients and they were confirmed to be down-regulated in another cohort of 68 patients. Then we divided the CTO patients into two groups according to CC grade (poor CC group, CC = 0 or one; good CC group, CC = 2). MiRNA-494, miRNA-495 and miRNA-329 were found to be down-regulated in good CC group compared with poor CC group. Analysis of the lncRNA-miRNA495-mRNA network showed 3 DE lncRNA sponges (NONHSAG008675, NONHSAG020957 and NONHSAG010989), 4 DE lncRNA targets (NONHSAT079547.2, NONHSAT081776.2, NONHSAT148555.1 and NONHSAT150928.1) and 2 DE mRNA targets (RAD54L2 and ZC3H4) of miRNA495.

Conclusion: This study revealed that the lncRNA-miRNA-mRNA network might play a critical role in angiogenesis in CTO patients.

Salvianolic acid B and ferulic acid synergistically promote angiogenesis in HUVECs and zebrafish via regulating VEGF signaling

ETHNOPHARMACOLOGICAL RELEVANCE

Induced vascular growth in the myocardium has been widely acknowledged as a promising intervention strategy for patients with ischemic coronary artery disease. Yet despite long-term efforts on gene, protein or cell-based pro-angiogenic therapies, the clinical translation remains challenging. Noticeably, multiple medicinal herbs have long-term documented effects in promoting blood circulation. Salvia miltiorrhiza and Ligusticum stratum are two representative traditional Chinese medicine herbs with suggested roles in enhancing organ blood supply, and Guanxinning Tablet (GXNT), a botanical drug which is formulated with these two herbs, exhibited significant efficacy against angina pectoris in clinical practices.

AIM OF THE STUDY

This study aimed to examine the pro-angiogenic activity of GXNT and its major components, as well as to explore their pharmacological mechanism in promoting angiogenesis.

MATERIALS AND METHODS

In vitro, the pro-angiogenic effects of GXNT and its major components were examined on human umbilical vein endothelial cells by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT), scratch assay, and endothelial cell tube formation assay. In vivo, the pro-angiogenic effects were examined on the ponatinib-induced angiogenesis defective zebrafish model. The active compounds were identified through phenotype-based screening in zebrafish, and their pharmacological mechanism was explored in both in vitro and in vivo models by immunofluorescent staining, cell cycle analysis, quantitative PCR and whole embryo in-situ hybridization.

RESULTS

We demonstrated strong pro-angiogenic effects of GXNT in both human umbilical vein endothelial cells and zebrafish model. Moreover, through phenotype-based screening in zebrafish for active compounds, pro-angiogenic effects was discovered for salvianolic acid B (Sal B), a major component of Salvia miltiorrhiza, and its activity was further enhanced when co-administered with ferulic acid (FA), which is contained in Ligusticum stratum. On the cellular level, Sal B and FA cotreatment increased endothelial cell proliferation of sprouting arterial intersomitic vessels in zebrafish, as well as largely restored G1-S cell cycle progression and cyclin D1 expression in angiogenic defective HUVECs. Through quantitative transcriptional analysis, increased expression of vegfr2 (kdr, kdrl) and vegfr1 was detected after GXNT or SalB/FA treatment, together with upregulated transcription of their ligands including vegf-a, vegf-b, and pgfb. Bevacizumab, an anti-human VEGF-A monoclonal antibody, was able to significantly, but not completely, block the pro-angiogenic effects of GXNT or SalB/FA, suggesting their multi-targeting properties.

CONCLUSIONS

In conclusion, from a traditional Chinese medicine with effects in enhancing blood circulation, we demonstrated the synergistic pro-angiogenic effects of Sal B and FA via both in vitro and in vivo models, which function at least partially through regulating the expression of VEGF receptors and ligands. Future studies are warranted to further elaborate the molecular interaction between these two compounds and the key regulators in the process of neovascularization.

Traditional Cardiovascular Risk Factors and Coronary Collateral Circulation: A Meta-Analysis

Objective: Patients with well-developed coronary collateral circulation (CC) usually have low mortality, improved cardiac function, and reduced infarct size. Currently, there is conflicting evidence on the association between traditional cardiovascular risk factors (diabetes, hypertension, and smoking habit) and CC.

Design: We performed a meta-analysis of case-control studies to better understand such associations.

Data Sources: We searched the MEDINE, EMBASE, and Science Citation Index databases to identify relevant studies.

Eligibility Criteria for Selecting Studies: Case control studies reporting data on risk factors (smoking habit, hypertension, and diabetes mellites) in comparing cases between poor CC and well-developed CC groups. Well-developed CC was the primary outcome of this meta-analysis

Data Extraction and Synthesis: Relevant data were extracted by two independent investigators. We derived pooled odds ratios (ORs) with random effects models. We performed quality assessments, publication bias, and sensitivity analysis to ensure the reliability of our results.

Results: In total, 18 studies that had 4,746 enrolled patients were analyzed. Our results showed that hypertension and smoking habit did not (OR = 0.94, 95% CI: 0.75–1.17, p = 0.564 and OR = 1.00, 95% CI: 0.84–1.18, p = 0.970, respectively), and diabetes did (OR = 0.50, 95% CI: 0.38–0.67, p = 0.00001) affect the development of CC.

Conclusion: Unlike hypertension and smoking habit, diabetes was associated with poor CC formation.

Trial Registration Number:https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=87821, identifier: CRD42018087821.

The association of interferon-alpha with development of collateral circulation after artery occlusion

Background

Previous studies have demonstrated that interferon (IFN) signaling is enhanced in patients with poor collateral circulation (CC). However, the role and mechanisms of IFN‐alpha in the development of CC remain unknown.

Methods

We studied the serum levels of IFN‐alpha and coronary CC in a case–control study using logistics regression, including 114 coronary chronic total occlusion (CTO) patients with good coronary CC and 94 CTO patients with poor coronary CC. Restricted cubic splines was used to flexibly model the association of the levels of IFN‐alpha with the incidence of good CC perfusion restoration after systemic treatment with IFN‐alpha was assessed in a mice hind‐limb ischemia model.

Results

Compared with the first IFN‐alpha tertile, the risk of poor CC was higher in the third IFN‐alpha tertile (OR: 4.79, 95% CI: 2.22–10.4, p < .001). A cubic spline‐smoothing curve showed that the risk of poor CC increased with increasing levels of serum IFN‐alpha. IFN‐alpha inhibited the development of CC in a hindlimb ischemia model. Arterioles of CC in the IFN‐alpha group were smaller in diameter than in the control group.

Conclusion

Patients with CTO and with poor CC have higher serum levels of IFN‐alpha than CTO patients with good CC. IFN‐alpha might impair the development of CC after artery occlusion.

Therapeutic angiogenesis in coronary artery disease: a review of mechanisms and current approaches

INTRODUCTION

Despite tremendous advances, the shortcomings of current therapies for coronary disease are evidenced by the fact that it remains the leading cause of death in many parts of the world. There is hence a drive to develop novel therapies to tackle this disease. Therapeutic approaches to coronary angiogenesis have long been an area of interest in lieu of its incredible, albeit unrealized potential.

AREAS COVERED

This paper offers an overview of mechanisms of native angiogenesis and a description of angiogenic growth factors. It progresses to outline the advances in gene and stem cell therapy and provides a brief description of other investigational approaches to promote angiogenesis. Finally, the hurdles and limitations unique to this particular area of study are discussed.

EXPERT OPINION

An effective, sustained, and safe therapeutic option for angiogenesis truly could be the paradigm shift for cardiovascular medicine. Unfortunately, clinically meaningful therapeutic options remain elusive because promising animal studies have not been replicated in human trials. The sheer complexity of this process means that numerous major hurdles remain before therapeutic angiogenesis truly makes its way from the bench to the bedside.

Metabolic syndrome and its components reduce coronary collateralization in chronic total occlusion: An observational study

Background

Metabolic syndrome (MetS) is an independent risk factor for the incidence of cardiovascular diseases. We investigated whether or to what extent MetS and its components was associated with coronary collateralization (CC) in chronic total occlusion (CTO).

Methods

This study involved 1653 inpatients with CTO. Data on demographic and clinical characteristics were collected by cardiovascular doctors. The CC condition was defined by the Rentrop scoring system. Subgroup analysis, mixed model regression analysis, scoring systems and receiver operating characteristic (ROC) curve analysis were performed.

Results

Overall, 1653 inpatients were assigned to the poor CC group (n = 355) and good CC group (n = 1298) with or without MetS. Compared to the good CCs, the incidence of MetS was higher among the poor CCs for all patients. Poor collateralization was present in 7.6%, 14.2%, 19.3%, 18.2%, 35.6% and 51.1% of the six groups who met the diagnostic criteria of MetS 0, 1, 2, 3, 4 and 5 times, respectively. For multivariable logistic regression, quartiles of BMI remained the risk factors for CC growth in all subgroups (adjusted OR = 1.755, 95% CI 1.510–2.038, P < 0.001 all patients; adjusted OR = 1.897, 95% CI 1.458–2.467, P < 0.001 non-MetS; and adjusted OR = 1.814, 95% CI 1.482–2.220, P < 0.001 MetS). After adjustment for potential confounding factors, MetS was an independent risk factor for CC growth in several models. Assigning a score of one for each component, the AUCs were 0.629 (95% CI 0.595–0.662) in all patients, 0.656 (95% CI 0.614–0.699) in MetS patients and 0.569 (95% CI 0.517–0.621) in non-MetS patients by receiver operating characteristic analysis.

Conclusions

MetS, especially body mass index, confers a greater risk of CC formation in CTO. The value of scoring systems should be explored further for CTO.

Contradictory Effect of Coronary Collateral Circulation on Regional Myocardial Perfusion That Assessed by Quantitative Myocardial Perfusion Scintigraphy

Background

Previous studies showed conflicting results about the contribution of coronary collateral circulation (CCC) to myocardial perfusion and function. The aim of this study was to investigate these contradictory problems by gated myocardial perfusion scintigraphy (gated MPS) for the first time.

Methods

The current cohort was retrospectively selected among patients who underwent gated MPS and coronary angiography within 2 months. Two different groups including 96 patients were assessed by gated MPS to detect the understanding of the miscellaneous effect of CCC on myocardial perfusion. Group 1 consisted of those who had collateral arteries that were not-well-developed (Rentrop grade 0 - 1) (n = 58), while group 2 consisted of those who had collateral arteries that were well-developed (Rentrop grade 2 - 3) (n = 38).

Results

There was no statistically significant difference between groups 1 and 2 in terms of perfusion and functional parameters obtained from gated MPS. Furthermore, no statistically significant difference was found in the phase analysis parameters which is a novel technique to evaluate left ventricular synchronization. On the other hand the left ventricular mass index values were high and quite close to the statistically significant value (P = 0.059) in group 2.

Conclusions

The current results that obtained by using the gated MPS technique for the first time in the evaluation of CCC showed that the well-developed collateral circulation has a positive effect on myocardial perfusion and function, but this effect was not statistically significant. Results need to be supported by large scale of patients’ size.

A simple coronary blood flow model to study the collateral flow index

In this work, we present a novel modeling framework to investigate the effects of collateral circulation into the coronary blood flow physiology. A prototypical model of the coronary tree, integrated with the concept of Collateral Flow Index (CFI), is employed to gain insight about the role of model parameters associated with the collateral circuitry, which results in physically-realizable solutions for specific CFI data. Then, we discuss the mathematical feasibility of pressure-derived CFI, anatomical implications and practical considerations involving the estimation of model parameters in collateral connections. A sensitivity analysis is carried out, and the investigation of the impact of the collateral circulation on FFR values is also addressed.

Cholesterol Efflux and Collateral Circulation in Chronic Total Coronary Occlusion: Effect-Circ Study

Background

The mechanism through which high‐density lipoprotein (HDL) induces cardioprotection is not completely understood. We evaluated the correlation between cholesterol efflux capacity (CEC), a functional parameter of HDL, and coronary collateral circulation (CCC). We additionally investigated whether A1BP (apoA1‐binding protein) concentration correlates with CEC and CCC.

Methods and Results

In this case‐control study, clinical and angiographic data were collected from 226 patients (mean age, 58 years; male, 72%) with chronic total coronary occlusion. CEC was assessed using a radioisotope and J774 cells, and human A1BP concentration was measured using enzyme‐linked immunosorbent assay. Differences between the good and poor CCC groups were compared, and associations between CEC, A1BP, and other variables were evaluated. Predictors of CCC were identified by multivariable logistic regression analysis. The CEC was higher in the good than in the poor CCC group (22.0±4.6% versus 20.2±4.7%; P=0.009). In multivariable analyses including age, sex, HDL‐cholesterol levels, age (odds ratio [OR], 0.96; P=0.003), and CEC (OR, 1.10; P=0.004) were identified as the independent predictors of good CCC. These relationships remained significant after additional adjustment for diabetes mellitus, acute coronary syndrome, and Gensini score. The A1BP levels were not significantly correlated with CCC (300 pg/mL and 283 pg/mL in the good CCC and poor CCC groups, respectively, P=0.25) or CEC.

Conclusions

The relationship between higher CEC and good CCC indicates that well‐functioning HDL may contribute to CCC and may be cardioprotective; this suggests that a specific function of HDL can have biological and clinical consequences.

Visfatin and 25-Hydroxyvitamin D3 Levels Affect Coronary Collateral Circulation Development in Patients with Chronic Coronary Total Occlusion

Background: Coronary collateral circulation (CCC) plays a vital role in the myocardial blood supply, especially forischemic myocardium. Evidence suggests that the visfatin and 25-hydroxyvitamin D3 [25(OH)D3] levels are related to the degree and incidence of vascular stenosis associated with coronary artery disease; however, few studies have evaluated the effect of visfatin and 25(OH)D3 on CCC development in patients with chronic total occlusion (CTO).This study aimed to evaluate the relationship between the serum visfatin and 25(OH)D3 levels and CCC in patients with CTO.Methods: A total of 189 patients with CTO confirmed by coronary angiography were included. CCC was graded from 0 to 3 according to the Rentrop-Cohen classification. Patients with grade 0 or grade 1 collateral development were included in the poor CCC group (n = 82), whereas patients with grade 2 or grade 3 collateral development were included in the good CCC group (n = 107). The serum visfatin and 25(OH)D3 levels were measured by ELISA.Results: The visfatin level was significantly higher in the poor CCC group than in the good CCC group, and the 25(OH)D3 level was significantly lower in the poor CCC group than in the good CCC group (P = 0.000). Correlation analysis showed that the Rentrop grade was negatively correlated with the visfatin level (r = − 0.692, P = 0.000) but positively correlated with the 25(OH)D3 level (r = 0.635, P = 0.000). Logistic regression analysis showed that the visfatin and 25(OH)D3 levels were independent risk factors for CCC (odds ratio 1.597, 95% confidence interval 1.300–1.961, P = 0.000 and odds ratio 0.566, 95% confidence interval 0.444–0.722, P = 0.000, respectively). The visfatin and25(OH)D3 levels can effectively predict the CCC status.Conclusion: Serum visfatin and 25(OH)D3 levels are related to CCC development and are independent predictors of poor CCC.

Coronary Collateral Microcirculation Reserve Becomes Vestigial with Aging

INTRODUCTION

Our previous study indicated that coronary collateral microcirculation reserve (CCMR), native collaterals, transports blood flow to an ischemic area to reduce ischemic tissue injury. This study aimed to observe the changes of CCMR in the hearts of different month-old rats.

METHODS

We selected 2-, 8-, 16-, and 24-month-old rats as the research objects to monitor the changes of CCMR in rats with aging. After acute myocardial infarction, lectin-FITC was injected into the femoral vein vessels of rats to mark CCMR vessels in the ischemic area.

RESULTS

Results of the lectin-FITC perfusion experiment indicated that the number and collagen IV coverage of CCMR vessels declined with aging. Moreover, data suggested a correlation between endothelial nitric oxide synthase and a decline in the number of CCMR vessels.

CONCLUSION

Aging causes CCMR decline in rats.

Coronary Microvascular Dysfunction

Many patients with chest pain undergoing coronary angiography do not show significant obstructive coronary lesions. A substantial proportion of these patients have abnormalities in the function and structure of coronary microcirculation due to endothelial and smooth muscle cell dysfunction. The coronary microcirculation has a fundamental role in the regulation of coronary blood flow in response to cardiac oxygen requirements. Impairment of this mechanism, defined as coronary microvascular dysfunction (CMD), carries an increased risk of adverse cardiovascular clinical outcomes. Coronary endothelial dysfunction accounts for approximately two-thirds of clinical conditions presenting with symptoms and signs of myocardial ischemia without obstructive coronary disease, termed "ischemia with non-obstructive coronary artery disease" (INOCA) and for a small proportion of "myocardial infarction with non-obstructive coronary artery disease" (MINOCA). More frequently, the clinical presentation of INOCA is microvascular angina due to CMD, while some patients present vasospastic angina due to epicardial spasm, and mixed epicardial and microvascular forms. CMD may be associated with focal and diffuse epicardial coronary atherosclerosis, which may reinforce each other. Both INOCA and MINOCA are more common in females. Clinical classification of CMD includes the association with conditions in which atherosclerosis has limited relevance, with non-obstructive atherosclerosis, and with obstructive atherosclerosis. Several studies already exist which support the evidence that CMD is part of systemic microvascular disease involving multiple organs, such as brain and kidney. Moreover, CMD is strongly associated with the development of heart failure with preserved ejection fraction (HFpEF), diabetes, hypertensive heart disease, and also chronic inflammatory and autoimmune diseases. Since coronary microcirculation is not visible on invasive angiography or computed tomographic coronary angiography (CTCA), the diagnosis of CMD is usually based on functional assessment of microcirculation, which can be performed by both invasive and non-invasive methods, including the assessment of delayed flow of contrast during angiography, measurement of coronary flow reserve (CFR) and index of microvascular resistance (IMR), evaluation of angina induced by intracoronary acetylcholine infusion, and assessment of myocardial perfusion by positron emission tomography (PET) and magnetic resonance (CMR).

Impact of coronary collateralization on long-term clinical outcomes in type 2 diabetic patients after successful recanalization of chronic total occlusion

Background

To assess the prognostic role of coronary collaterals in patients with type 2 diabetes mellitus (T2DM) after successful percutaneous coronary intervention (PCI) for chronic total occlusion (CTO).

Methods

Coronary collateralization was graded according to Rentrop scoring system in 198 type 2 diabetic patients and 335 non-diabetics with stable angina undergoing PCI for at least one CTO lesion. Left ventricular ejection fraction (LVEF) was determined and major adverse cardio-cerebral events (MACCE) were recorded during follow-up.

Results

Poor collateralization was more common in patients with T2DM than in non-diabetics (40% vs 29%, p = 0.008). At 13.5 ± 4.1 months, the rate of composite MACCE (17.3% vs 27.6%, p = 0.034) and repeat revascularization (15.2% vs 25.5%, p = 0.026) was lower and the increase in LVEF (3.10% vs 1.80%, p = 0.024) was greater in patients with good collaterals than in those with poor collaterals for non-diabetic group. The associations were in the same direction for T2DM group (35% vs 44%; 30% vs 36%; 2.14% vs 1.65%, respectively) with a higher all-cause mortality in diabetic patients with poor collaterals (p = 0.034). Multivariable Cox proportional hazards analysis showed that coronary collateralization was an independent factor for time to MACCE (HR 2.155,95% CI 1.290–3.599, p = 0.003) and repeat revascularization (HR 2.326, 95% CI 1.357–3.986, p = 0.002) in non-diabetic patients, but did not enter the model in those with T2DM.

Conclusions

T2DM is associated with reduced coronary collateralization. The effects of the status of coronary collateralization on long-term clinical outcomes and left ventricular function appear to be similar in size in type 2 diabetic patients and non-diabetics after successful recanalization of CTO.

The hydromechanics in arteriogenesis

Coronary heart diseases are tightly associated with aging. Although current revascularization therapies, such as percutaneous coronary interventions (PCI) and coronary artery bypass graft (CABG), improve the clinical outcomes of patients with coronary diseases, their application and therapeutic effects are limited in elderly patients. Thus, developing novel therapeutic strategies, like prompting collateral development or the process of arteriogenesis, is necessary for the treatment of the elderly with coronary diseases. Arteriogenesis (ie, the vascular remodeling from pre‐existent arterioles to collateral conductance networks) functions as an essential compensation for tissue hypoperfusion caused by artery occlusion or stenosis, and its mechanisms remain to be elucidated. In this review, we will summarize the roles of the major hydromechanical components in laminar conditions in arteriogenesis, and discuss the potential effects of disturbed flow components in non‐laminar conditions.

Effective myocardial perfusion and concomitant haemodynamic status determine the clinical diversity of anomalous left coronary artery from the pulmonary artery

BACKGROUND

Anomalous left coronary artery from the pulmonary artery is a rare congenital heart disease (CHD) with diverse clinical presentations despite the same anatomy. Factors determining this heterogeneous presentation are not well understood.

METHOD AND RESULTS

We retrospectively investigated 14 patients (12 females) who underwent surgical repair of anomalous left coronary artery from the pulmonary artery. These patients were divided into three groups based upon the severity of initial presentation: (1) severe, life-threatening condition (n = 5), (2) mild-to-moderate distress (n = 6), and (3) asymptomatic (n = 3). All patients presented with left ventricular dilation and retrograde flow in left coronary artery by echocardiogram. Eight patients in (1) and (2) presented with severe left ventricular dysfunction. All but one showed abnormal ECG consistent with myocardial ischemia or infarction. Asymptomatic patients had preserved left ventricular systolic function despite ischemic findings on ECG. In 13 patients after surgical repair, all but one normalised left ventricular geometry and systolic function, suggesting nearly full myocardial recovery upon improvement of myocardial perfusion; 8 patients had residual echogenic papillary muscle with variable degree of mitral regurgitation.

CONCLUSIONS

Evidence of myocardial ischemic injury was present in all patients with anomalous left coronary artery from the pulmonary artery regardless of their initial presentation. Retrograde flow in left coronary artery, implying collateral vessel development from right coronary artery to left coronary artery, was noted in all patients, yet only few patients had preserved systolic function at the time of diagnosis. The balance between effective myocardial perfusion and a deleterious fistulous flow provided by these collaterals and the simultaneous haemodynamic status are what determine the clinical diversity of anomalous left coronary artery from the pulmonary artery.

Invasive Assessment of the Myocardial Microcirculation during Beating Heart Coronary Artery Bypass Grafting

Coronary artery bypass grafting may be associated with several cardiac complications, including ischemia, acute myocardial infarction, arrhythmias, or hemodynamic instability. Accumulating evidence suggests that well-developed coronary collateral circulation may protect against adverse effects, including myocardial ischemia. Assessment of myocardial microvascular perfusion is, therefore, of great clinical interest in beating heart surgery. In this paper, myocardial microvascular perfusion is continuously assessed on the beating heart using laser Doppler flowmetry in consecutive patients who underwent coronary artery bypass grafting procedures. No significant (p = 0.110) differences were found between the averaged perfusion signal (n = 42) at the baseline, during artery occlusion, or after reperfusion (732.4 ± 148.0 vs. 711.4 ± 144.1 vs. 737.0 ± 141.2, respectively). In contrast, significantly different (p < 0.001) mean perfusion signals (n = 12) were found (805.4 ± 200.1 vs. 577.2 ± 212.8 vs. 649.3 ± 220.8) in a subset of patients who presented with hemodynamic instability and myocardial ischemia. Additionally, a strong positive correlation between the plasma levels of high-sensitivity troponin I and perfusion decrease level after artery occlusion was found (r = 0.854, p < 0.001). This study argues that myocardial microvascular perfusion remains constant during coronary artery bypass grafting on the beating heart in advanced coronary artery disease. This phenomenon is most likely due to an extensive coronary collateral circulation.

The Roles of AMPK in Revascularization

Coronary heart disease (CHD) is the most common and serious illness in the world and has been researched for many years. However, there are still no real effective ways to prevent and save patients with this disease. When patients present with myocardial infarction, the most important step is to recover ischemic prefusion, which usually is accomplished by coronary artery bypass surgery, coronary artery intervention (PCI), or coronary artery bypass grafting (CABG). These are invasive procedures, and patients with extensive lesions cannot tolerate surgery. It is, therefore, extremely urgent to search for a noninvasive way to save ischemic myocardium. After suffering from ischemia, cardiac or skeletal muscle can partly recover blood flow through angiogenesis (de novo capillary) induced by hypoxia, arteriogenesis, or collateral growth (opening and remodeling of arterioles) triggered by dramatical increase of fluid shear stress (FSS). Evidence has shown that both of them are regulated by various crossed pathways, such as hypoxia-related pathways, cellular metabolism remodeling, inflammatory cells invasion and infiltration, or hemodynamical changes within the vascular wall, but still they do not find effective target for regulating revascularization at present. 5′-Adenosine monophosphate-activated protein kinase (AMPK), as a kinase, is not only an energy modulator but also a sensor of cellular oxygen-reduction substances, and many researches have suggested that AMPK plays an essential role in revascularization but the mechanism is not completely understood. Usually, AMPK can be activated by ADP or AMP, upstream kinases or other cytokines, and pharmacological agents, and then it phosphorylates key molecules that are involved in energy metabolism, autophagy, anti-inflammation, oxidative stress, and aging process to keep cellular homeostasis and finally keeps cell normal activity and function. This review makes a summary on the subunits, activation and downstream targets of AMPK, the mechanism of revascularization, the effects of AMPK in endothelial cells, angiogenesis, and arteriogenesis along with some prospects.

Topologic and Hemodynamic Characteristics of the Human Coronary Arterial Circulation

Background

Many processes contributing to the functional and structural regulation of the coronary circulation have been identified. A proper understanding of the complex interplay of these processes requires a quantitative systems approach that includes the complexity of the coronary network. The purpose of this study was to provide a detailed quantification of the branching characteristics and local hemodynamics of the human coronary circulation.

Methods

The coronary arteries of a human heart were filled post-mortem with fluorescent replica material. The frozen heart was alternately cut and block-face imaged using a high-resolution imaging cryomicrotome. From the resulting 3D reconstruction of the left coronary circulation, topological (node and loop characteristics), topographic (diameters and length of segments), and geometric (position) properties were analyzed, along with predictions of local hemodynamics (pressure and flow).

Results

The reconstructed left coronary tree consisted of 202,184 segments with diameters ranging from 30 μm to 4 mm. Most segments were between 100 μm and 1 mm long. The median segment length was similar for diameters ranging between 75 and 200 μm. 91% of the nodes were bifurcations. These bifurcations were more symmetric and less variable in smaller vessels. Most of the pressure drop occurred in vessels between 200 μm and 1 mm in diameter. Downstream conductance variability affected neither local pressure nor median local flow and added limited extra variation of local flow. The left coronary circulation perfused 358 cm³ of myocardium. Median perfused volume at a truncation level of 100 to 200 μm was 20 mm³ with a median perfusion of 5.6 ml/min/g and a high local heterogeneity.

Conclusion

This study provides the branching characteristics and hemodynamic analysis of the left coronary arterial circulation of a human heart. The resulting model can be deployed for further hemodynamic studies at the whole organ and local level.

Co-morbidities and co-medications as confounders of cardioprotection-Does it matter in the clinical setting?

The translation of cardioprotection from robust experimental evidence to beneficial clinical outcome for patients suffering acute myocardial infarction or undergoing cardiovascular surgery has been largely disappointing. The present review attempts to critically analyse the evidence for confounders of cardioprotection in patients with acute myocardial infarction and in patients undergoing cardiovascular surgery. One reason that has been proposed to be responsible for such lack of translation is the confounding of cardioprotection by co-morbidities and co-medications. Whereas there is solid experimental evidence for such confounding of cardioprotection by single co-morbidities and co-medications, the clinical evidence from retrospective analyses of the limited number of clinical data is less robust. The best evidence for interference of co-medications is that for platelet inhibitors to recruit cardioprotection per se and thus limit the potential for further protection from myocardial infarction and for propofol anaesthesia to negate the protection from remote ischaemic conditioning in cardiovascular surgery. LINKED ARTICLES: This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.23/issuetoc.

NFAT5 promotes arteriogenesis via MCP-1-dependent monocyte recruitment

Studies have demonstrated that nuclear factor of activated T cells 5 (NFAT5) is not only a tonicity‐responsive transcription factor but also activated by other stimuli, so we aim to investigate whether NFAT5 participates in collateral arteries formation in rats. We performed femoral artery ligature (FAL) in rats for hindlimb ischaemia model and found that NFAT5 was up‐regulated in rat adductors with FAL compared with sham group. Knockdown of NFAT5 with locally injection of adenovirus‐mediated NFAT5‐shRNA in rats significantly inhibited hindlimb blood perfusion recovery and arteriogenesis. Moreover, NFAT5 knockdown decreased macrophages infiltration and monocyte chemotactic protein‐1 (MCP‐1) expression in rats adductors. In vitro, with interleukin‐1β (IL‐1β) stimulation and loss‐of‐function studies, we demonstrated that NFAT5 knockdown inhibits MCP‐1 expression in endothelial cells and chemotaxis of THP‐1 cells regulated by ERK1/2 pathway. More importantly, exogenous MCP‐1 delivery could recover hindlimb blood perfusion, promote arteriogenesis and macrophages infiltration in rats after FAL, which were depressed by NFAT5 knockdown. Besides, NFAT5 knockdown also inhibited angiogenesis in gastrocnemius muscles in rats. Our results indicate that NFAT5 is a critical regulator of arteriogenesis and angiogenesis via MCP‐1‐dependent monocyte recruitment, suggesting that NFAT5 may represent an alternative therapeutic target for ischaemic diseases.

Searching for optimal blood pressure targets in type 2 diabetic patients with coronary artery disease

BACKGROUND

Controversies exist regarding the optimal blood pressure (BP) level that is safe and provides cardiovascular protection in patients with type 2 diabetes mellitus (T2DM) and coexistent coronary artery disease. Several new glucose-lowering agents have been found to lower BP as well, making the interaction between BP and T2DM even more complex.

METHODS

With the reference to recent literature, this review article describes the potential mechanisms of increased risk of hypertension in T2DM and outlines the possible optimal BP levels based upon recommendations on the management of hypertension by the current guidelines, in combination with our research findings, for type 2 diabetic patients with coronary artery disease.

RESULTS

The development of hypertension in T2DM involves multiple processes, including enhanced sympathetic output, inappropriate activation of renin-angiotensin- aldosterone system, endothelial dysfunction induced through insulin resistance, and abnormal sodium handling by the kidney. Both AGE-RAGE axis and adipokine dysregulation activate intracellular signaling pathways, increase oxidative stress, and aggravate vascular inflammation. Pancreatic β-cell specific microRNAs are implicated in gene expression and diabetic complications. Non-pharmacological intervention with lifestyle changes improves BP control, and anti-hypertensive medications with ACEI/ARB, calcium antagonists, β-blockers, diuretics and new hypoglycemic agent SGLT2 inhibitors are effective to decrease mortality and prevent major adverse cardiovascular events. For hypertensive patients with T2DM and stable coronary artery disease, control of BP < 130/80 mmHg but not < 120/70 mmHg is reasonable, whereas for those with chronic total occlusion or acute coronary syndromes, an ideal BP target may be somewhat higher (< 140/90 mmHg). Caution is advised with aggressive lowering of diastolic BP to a critical threshold (< 60 mmHg).

CONCLUSIONS

Hypertension and T2DM share certain similar aspects of pathophysiology, and BP control should be individualized to minimize adverse events and maximize benefits especially for patients with T2DM and coronary artery disease.

Gata4-Dependent Differentiation of c-Kit+-Derived Endothelial Cells Underlies Artefactual Cardiomyocyte Regeneration in the Heart

Supplemental Digital Content is available in the text.

Background:

Although c-Kit⁺ adult progenitor cells were initially reported to produce new cardiomyocytes in the heart, recent genetic evidence suggests that such events are exceedingly rare. However, to determine if these rare events represent true de novo cardiomyocyte formation, we deleted the necessary cardiogenic transcription factors Gata4 and Gata6 from c-Kit–expressing cardiac progenitor cells.

Methods:

Kit allele–dependent lineage tracing and fusion analysis were performed in mice following simultaneous Gata4 and Gata6 cell type–specific deletion to examine rates of putative de novo cardiomyocyte formation from c-Kit⁺ cells. Bone marrow transplantation experiments were used to define the contribution of Kit allele–derived hematopoietic cells versus Kit lineage–dependent cells endogenous to the heart in contributing to apparent de novo lineage-traced cardiomyocytes. A Tie2^CreERT2 transgene was also used to examine the global impact of Gata4 deletion on the mature cardiac endothelial cell network, which was further evaluated with select angiogenesis assays.

Results:

Deletion of Gata4 in Kit lineage–derived endothelial cells or in total endothelial cells using the Tie2^CreERT2 transgene, but not from bone morrow cells, resulted in profound endothelial cell expansion, defective endothelial cell differentiation, leukocyte infiltration into the heart, and a dramatic increase in Kit allele–dependent lineage-traced cardiomyocytes. However, this increase in labeled cardiomyocytes was an artefact of greater leukocyte-cardiomyocyte cellular fusion because of defective endothelial cell differentiation in the absence of Gata4.

Conclusions:

Past identification of presumed de novo cardiomyocyte formation in the heart from c-Kit⁺ cells using Kit allele lineage tracing appears to be an artefact of labeled leukocyte fusion with cardiomyocytes. Deletion of Gata4 from c-Kit⁺ endothelial progenitor cells or adult endothelial cells negatively impacted angiogenesis and capillary network integrity.

Exercise Training as a Mediator for Enhancing Coronary Collateral Circulation: A Review of the Evidence

Coronary collateral vessels supply blood to areas of myocardium at risk after arterial occlusion. Flow through these channels is driven by a pressure gradient between the donor and the occluded artery. Concomitant with increased collateral flow is an increase in shear force, a potent stimulus for collateral development (arteriogenesis). Arteriogenesis is self-limiting, often ceasing prematurely when the pressure gradient is reduced by the expanding lumen of the collateral vessel. After the collateral has reached its self-limited maximal conductance, the only way to drive further increases is to re-establish the pressure gradient.

During exercise, the myocardial oxygen demand is increased, subsequently increasing coronary flow. Therefore, exercise may represent a means of driving augmented arteriogenesis in patients with stable coronary artery disease. Studies investigating the ability of exercise to drive collateral development in humans are inconsistent. However, these inconsistencies may be due to the heterogeneity of assessment methods used to quantify change. This article summarises current evidence pertaining to the role of exercise in the development of coronary collaterals, highlighting areas of future research.

Influence of Cardiovascular Risk Factors, Comorbidities, Medication Use and Procedural Variables on Remote Ischemic Conditioning Efficacy in Patients with ST-Segment Elevation Myocardial Infarction

Remote ischemic conditioning (RIC) confers cardioprotection in patients with ST-segment elevation myocardial infarction (STEMI). Despite intense research, the translation of RIC into clinical practice remains a challenge. This may, at least partly, be due to confounding factors that may modify the efficacy of RIC. The present review focuses on cardiovascular risk factors, comorbidities, medication use and procedural variables which may modify the efficacy of RIC in patients with STEMI. Findings of such efficacy modifiers are based on subgroup and post-hoc analyses and thus hold risk of type I and II errors. Although findings from studies evaluating influencing factors are often ambiguous, some but not all studies suggest that smoking, non-statin use, infarct location, area-at-risk of infarction, pre-procedural Thrombolysis in Myocardial Infarction (TIMI) flow, ischemia duration and coronary collateral blood flow to the infarct-related artery may influence on the cardioprotective efficacy of RIC. Results from the on-going CONDI2/ERIC-PPCI trial will determine any clinical implications of RIC in the treatment of patients with STEMI and predefined subgroup analyses will give further insight into influencing factors on the efficacy of RIC.

Lipoprotein (a) interactions with cholesterol-containing lipids on angiographic coronary collateralization in type 2 diabetic patients with chronic total occlusion

Background

We investigated whether or to what extent the interaction of lipoprotein (a) [Lp(a)] with cholesterol-containing lipids was associated with angiographic coronary collateralization in type 2 diabetic patients with chronic total occlusion.

Methods

Serum levels of Lp(a), total cholesterol, low-density lipoprotein–cholesterol (LDL-C), high-density lipoprotein–cholesterol (HDL-C), and triglyceride were determined and non-HDL-C was calculated in 706 type 2 diabetic and 578 non-diabetic patients with stable coronary artery disease and angiographic total occlusion of at least one major coronary artery. The degree of collaterals supplying the distal aspect of a total occlusion from the contra-lateral vessel was graded as poor (Rentrop score of 0 or 1) or good coronary collateralization (Rentrop score of 2 or 3).

Results

For diabetic and non-diabetic patients, Lp(a), total cholesterol, LDL-C, and non-HDL-C levels were higher in patients with poor coronary collateralization than in those with good collateralization, whereas HDL-C and triglyceride levels were similar. After adjustment for potential confounding factors, tertiles of Lp(a), total cholesterol, LDL-C and non-HDL-C remained independent determinants for poor collateralization. A significant interaction between Lp(a) and total cholesterol, LDL-C or non-HDL-C was observed in diabetic patients (all P interaction < 0.001) but not in non-diabetics. At high tertile of total cholesterol (≥ 5.35 mmol/L), LDL-C (≥ 3.36 mmol/L) and non-HDL-C (≥ 4.38 mmol/L), diabetic patients with high tertile of Lp(a) (≥ 30.23 mg/dL) had an increased risk of poor collateralization compared with those with low tertile of Lp(a) (< 12.66 mg/dL) (adjusted OR = 4.300, 3.970 and 4.386, respectively, all P < 0.001).

Conclusions

Increased Lp(a) confers greater risk for poor coronary collateralization when total cholesterol, LDL-C or non-HDL-C are elevated especially for patients with type 2 diabetes.

Electronic supplementary material

The online version of this article (10.1186/s12933-019-0888-z) contains supplementary material, which is available to authorized users.

Vascular Remodeling of Visceral Arteries Following Interruption of the Splenic Artery During Liver Transplantation

Splenic artery (SA) ligation can be performed during liver transplantation (LT) to avoid portal hyperperfusion, which is involved in the pathogenesis of both small-for-size and SA syndrome. The SA can also be used as an inflow for arterial reconstruction. Exceptionally, SA interruption or agenesis has been associated with positive remodeling of collateral arteries supplying the spleen via the left gastric artery (LGA), short gastric vessels, and the gastroepiploic arcade (GEA), with subsequent severe upper gastrointestinal (GI) bleeding. To determine incidence, magnitude, predictors, and clinical implications of vascular remodeling after SA interruption during LT, we identified 465 patients transplanted in the period 2007-2017 who had the SA ligated or interrupted at LT. Among them, 88 had a computed tomography angiography suitable for evaluation of vascular remodeling after LT. The presence of prominent gastric arterial collaterals and the increase in LGA and GEA diameter were evaluated on 2-dimensional axial images and multiplanar reconstructions. Of the 88 patients, 28 (31.8%), 32 (36.4%), and 22 (25.0%) developed gastric collateralization graded as mild, moderate, or severe. Of the patients for whom comparison with pre-LT imaging was possible (n = 54), 51 (94.4%) presented a median 37% and 55% increase in LGA and GEA diameter, respectively. Severe gastric collateralization was associated with lower body mass index (odds ratio, 0.84; 95% confidence interval [CI], 0.71-0.98; P = 0.03), whereas a GEA caliper measurement increase was positively correlated with Model for End-Stage Liver Disease score (r² = 0.12; 95% CI, 0.65-4.15; P = 0.008). Out of 465 patients, 2 (0.43%) had severe episodes of arterial upper GI bleeding, possibly exacerbated by vascular remodeling. In conclusion, vascular remodeling after SA interruption during LT is frequent and can aggravate GI bleeding during follow-up.

Efficacy of mesenchymal stem cell therapy in systolic heart failure: a systematic review and meta-analysis

Background

Heart failure (HF) is the end stage of most heart disease. Mesenchymal stem cells (MSCs), with their specific biological effects, have been applied in several clinical trials to evaluate the efficacy in HF therapy. We performed this meta-analysis to review the clinical evidence of their therapeutic effect on HF.

Methods

Three databases were searched. The outcomes of interest were death, readmission, the 6-min walk test (6MWT), New York Heart Association (NYHA) class and left ventricular ejection fraction (LVEF). The relative risk (RR) and weighted mean difference (WMD) were calculated to evaluate the effects of MSCs on HF compared to placebo.

Results

A total of nine studies were included, involving 612 patients who underwent MSCs or placebo treatment. The overall rate of death showed a trend of reduction of 36% (RR [CI] = 0.64 [0.35, 1.16], p = 0.143) in the MSC treatment group. The incidence of readmission was reduced by 34% (RR [CI] = 0.66 [0.51, 0.85], p = 0.001). The patients in the MSC treatment group realised an average of 40.44 m (WMD [95% CI] = 40.44 m [19.07, 61.82], p < 0.0001) improvement in 6MWT. The NYHA class was reduced obviously in the MSC group (WMD [95% CI] = − 0.42 [− 0.64, − 0.20], p < 0.0001). The changes of LVEF from baseline were significantly more than 5.25% (WMD [95% CI] = 5.25 [3.58, 6.92], p < 0.0001) in the MSCs group, unlike in the placebo group.

Conclusions

Our results suggested that MSC treatment is an effective therapy for HF by improving the prognosis and exercise capacity. SCs derived from allosomes have superior therapeutic effects, and intracoronary injection is the optimum MSC delivery approach. Short-term cryopreservation is feasible in MSCs storage or transport.

The dynamics of monocytes in the process of collateralization

Collateralization is an important way for patients with coronary heart disease to supply blood flow to the ischemic area. At present, research on the mechanism of collateral circulation mainly focuses on the inflammatory response. Monocytes are the kernel of inflammatory response during arteriogenesis. Therefore, we reviewed the recent developments in this field in terms of the dynamic changes of monocytes during collateralization. We searched and scanned PubMed for the following terms until November 2018: collateral, collateralization, monocyte, macrophage, and arteriogenesis. Articles were obtained and examined to figure out the dynamics of monocytes in the progress of collateralization. Substantial research shows that recruitment, infiltration, and phenotypic transformation of monocytes can affect function in various ways, respectively. Mechanical or chemical factors that can produce effects on collateral development may be due partly to impact on dynamics of monocytes. Although mechanisms of dynamics of monocytes during arteriogenesis are not elucidated clearly, there is no doubt that deeper exploration of the underlying mechanisms will contribute to pharmaceutical development aiming for promoting collateral development.

A Unique Collateral Artery Development Program Promotes Neonatal Heart Regeneration

Collateral arteries are an uncommon vessel subtype that can provide alternate blood flow to preserve tissue following vascular occlusion. Some patients with heart disease develop collateral coronary arteries, and this correlates with increased survival. However, it is not known how these collaterals develop or how to stimulate them. We demonstrate that neonatal mouse hearts use a novel mechanism to build collateral arteries in response to injury. Arterial endothelial cells (ECs) migrated away from arteries along existing capillaries and reassembled into collateral arteries, which we termed "artery reassembly". Artery ECs expressed CXCR4, and following injury, capillary ECs induced its ligand, CXCL12. CXCL12 or CXCR4 deletion impaired collateral artery formation and neonatal heart regeneration. Artery reassembly was nearly absent in adults but was induced by exogenous CXCL12. Thus, understanding neonatal regenerative mechanisms can identify pathways that restore these processes in adults and identify potentially translatable therapeutic strategies for ischemic heart disease.

Cardioprotection during ischemia by coronary collateral growth

Ischemic heart diseases (IHD) cause millions of deaths around the world annually. While surgical and pharmacological interventions are commonly used to treat patients with IHD, their efficacy varies from patient to patient and is limited by the severity of the disease. One promising, at least theoretically, approach for treating IHD is induction of coronary collateral growth (CCG). Coronary collaterals are arteriole-to-arteriole anastomoses that can undergo expansion and remodeling in the setting of coronary disease when the disease elicits myocardial ischemia and creates a pressure difference across the collateral vessel that creates unidirectional flow. Well-developed collaterals can restore blood flow in the ischemic area of the myocardium and protect the myocardium at risk. Moreover, such collaterals are correlated to reduced mortality and infarct size and better cardiac function during occlusion of coronary arteries. Therefore, understanding the process of CCG is highly important as a potentially viable treatment of IHD. While there are several excellent review articles on this topic, this review will provide a unified overview of the various aspects related to CCG as well as an update of the advancements in the field. We also call for more detailed studies with an interdisciplinary approach to advance our knowledge of CCG. In this review, we will describe growth of coronary collaterals, the various factors that contribute to CCG, animal models used to study CCG, and the cardioprotective effects of coronary collaterals during ischemia. We will also discuss the impairment of CCG in metabolic syndrome and the therapeutic potentials of CCG in IHD.

The relationship of plasma miR-503 and coronary collateral circulation in patients with coronary artery disease

OBJECTIVE

Although angiogenesis plays an important role in coronary collateral circulation (CCC) formation and there are many determinants of coronary angiogenesis, they cannot fully explain the mechanism of CCC formation or as potent biomarker for CCC status. Therefore, there is of great clinical significance to identify the novel molecules associated with CCC. Previously, miR-503 exerts anti-angiogenesis effect via inhibition of VEGF-A and its expression is associated with many angiogenesis-related factors. Thus, we aimed to investigate the relationship of plasma miR-503 with CCC formation as well as its predictive power for CCC status in patients with coronary artery disease.

METHODS

Among patients who underwent coronary angiography with coronary artery disease and a stenosis of ≥90% were included in our study. Collateral degree was graded according to Rentrop Cohen classification. The patients were divided to good CCC group (grade 2 or 3) and poor CCC group (grade 0 or 1) according to Rentrop grade. We investigated the plasma levels of miR-503 and VEGF-A by ELISA or q RT-PCR, respectively. In addition, we assayed the correlations of plasma miR-503 with VEGF-A or Rentrop grade using the spearman correlation test and its predictive power by receiver operating characteristic (ROC) and binary logistical regression analysis.

RESULTS

Our data showed that plasma VEGF-A was significantly higher in good CCC group than that in poor group. Plasma miR-503 was lower in CAD patients with good CCC or poor CCC compared with control subjects and lowest in good CCC group. In addition, miR-503 negatively correlated with VEGF-A and Rentrop grade, respectively. Moreover, miR-503 displayed more potent predictive power for CCC status than VEGF-A, but its sensitivity and specificity for CCC status were only 72.4 or 60.9%, respectively.

CONCLUSIONS

Lower plasma miR-503 level was related to better CCC formation, accompanied by up-regulation of VEGF-A. In addition, miR-503 displayed potent predictive power for CCC status, but its sensitivity and specificity were not high enough, indicating that miR-503 might be as an additional prognosis biomarker for CCC.

Donor artery stenosis interactions with diastolic blood pressure on coronary collateral flow in type 2 diabetic patients with chronic total occlusion

Background

We investigated whether and to what extent stenosis of predominant collateral donor artery (PCDA) affects coronary collateral flow in relation to blood pressure (BP) in type 2 diabetic patients with chronic total occlusion (CTO).

Methods

Collateral flow index (CFI) as derived from intracoronary pressure distal to occluded segment and mean aortic pressure in 220 type 2 diabetic patients and 220 propensity score matched non-diabetic controls undergoing percutaneous coronary intervention for CTO. The severity of PCDA stenosis was graded according to lumen diameter narrowing.

Results

CFI decreased stepwise from mild to severe stenosis of the PCDA and was lower in diabetic patients with moderate or severe PCDA stenosis than in non-diabetic controls (0.36 ± 0.10 vs. 0.45 ± 0.08, P < 0.001; 0.29 ± 0.09 vs. 0.35 ± 0.08, P = 0.008). When the PCDA was mildly stenotic, CFI increased initially along with a reduction in diastolic BP, and decreased when diastolic BP was below 60 mmHg in diabetic patients (0.38 ± 0.16 vs. 0.57 ± 0.09, P < 0.001). In the presence of moderate PCDA stenosis, diabetic patients had significantly lower CFI compared to non-diabetic controls, with a relative reduction of 19.8% at diastolic BP 70–79 mmHg, 28.2% at 60–69 mmHg and 38.2% below 60 mmHg (all P < 0.05). A severe PCDA stenosis resulted in a more pronounced decrease in CFI, with a relative reduction of 37.3% for diabetics compared to non-diabetics when diastolic BP was below 60 mmHg (P = 0.050).

Conclusions

In the setting of CTO, donor artery stenosis confers greater risk for reduced coronary collateral flow when diastolic BP is decreased. Even a moderate stenosis in the PCDA may be associated with lower collateral flow as diastolic BP decreases below 80 mmHg in type 2 diabetic than in non-diabetic patients.

Clinical translation of myocardial conditioning

Rapid admission and acute interventional treatment combined with modern antithrombotic pharmacologic therapy have improved outcomes in patients with ST elevation myocardial infarction. The next major target to further advance outcomes needs to address ischemia-reperfusion injury, which may contribute significantly to the final infarct size and hence mortality and postinfarction heart failure. Mechanical conditioning strategies including local and remote ischemic pre-, per-, and postconditioning have demonstrated consistent cardioprotective capacities in experimental models of acute ischemia-reperfusion injury. Their translation to the clinical scenario has been challenging. At present, the most promising mechanical protection strategy of the heart seems to be remote ischemic conditioning, which increases myocardial salvage beyond acute reperfusion therapy. An additional aspect that has gained recent focus is the potential of extended conditioning strategies to improve physical rehabilitation not only after an acute ischemia-reperfusion event such as acute myocardial infarction and cardiac surgery but also in patients with heart failure. Experimental and preliminary clinical evidence suggests that remote ischemic conditioning may modify cardiac remodeling and additionally enhance skeletal muscle strength therapy to prevent muscle waste, known as an inherent component of a postoperative period and in heart failure. Blood flow restriction exercise and enhanced external counterpulsation may represent cardioprotective corollaries. Combined with exercise, remote ischemic conditioning or, alternatively, blood flow restriction exercise may be of aid in optimizing physical rehabilitation in populations that are not able to perform exercise practice at intensity levels required to promote optimal outcomes.

Reduced coronary collateralization in type 2 diabetic patients with chronic total occlusion

BACKGROUND

The extent of coronary collateral formation is a primary determinant of the severity of myocardial damage and mortality after coronary artery occlusion. Type 2 diabetes mellitus (T2DM) represents an important risk factor for impaired collateral vessel growth. However, the mechanism of reduced coronary collateralization in type 2 diabetic patients remains unclear.

METHODS

With the reference to the recent researches, this review article describes the pathogenic effects of T2DM on collateral development and outlines possible clinical and biochemical markers associated with reduced coronary collateralization in type 2 diabetic patients with chronic total occlusion (CTO).

RESULTS

Diffuse coronary atherosclerosis in T2DM reduces pressure gradient between collateral donor artery and collateral recipient one, limiting collateral vessel growth and function. An interaction between advanced glycation end-products and their receptor activates several intracellular signaling pathways, enhances oxidative stress and aggravates inflammatory process. Diabetic condition decreases pro-angiogenic factors especially vascular endothelial growth factor and other collateral vessel growth related parameters. Numerous clinical and biochemical factors that could possibly attenuate the development of coronary collaterals have been reported. Increased serum levels of glycated albumin, cystatin C, and adipokine C1q tumor necrosis factor related protein 1 were associated with poor coronary collateralization in type 2 diabetic patients with stable coronary artery disease and CTO. Diastolic blood pressure and stenosis severity of the predominant collateral donor artery also play a role in coronary collateral formation.

CONCLUSIONS

T2DM impairs collateral vessel growth through multiple mechanisms involving arteriogenesis and angiogenesis, and coronary collateral formation in patients with T2DM and CTO is influenced by various clinical, biochemical and angiographic factors. This information provides insights into the understanding of coronary pathophysiology and searching for potential new therapeutic targets in T2DM.

Tissue Engineering the Vascular Tree

A major hurdle in the field of tissue engineering and regenerative medicine remains the design and construction of larger (> 1 cm3) in vitro tissues for biological studies and transplantation. While there has been success in creating three-dimensional (3D) capillary networks, relatively large arteries (diameter >3-5 mm), and more recently small arteries (diameter 500 μm-1 mm), there has been no success in the creation of a living dynamic blood vessel network comprising of arterioles (diameter 40-300 μm), capillaries, and venules. Such a network would provide the foundation to supply nutrients and oxygen to all surrounding cells for larger tissues and organs that require a hierarchical vascular supply. In this study, we describe the different technologies and methods that have been employed in an effort to create individual vessels and networks of vessels to support engineered tissues for in vivo and in vitro applications. A special focus is placed on the generation of blood vessels with average dimensions that span from microns (capillaries) to a millimeter (large arterioles). We also identify major challenges while exploring new opportunities to create model systems of the entire vascular tree, including arterioles and venules.

Porcine arteriogenesis based on vasa vasorum in a novel semi-acute occlusion model using high-resolution imaging

Bridging collaterals (BC) develop in several chronic total artery occlusion diseases, and can prevent extensive myocardial necrosis. Yet, their origin, growth process, and histo-morphology are still unclear. Since vasa vasorum (VV) may take part in collateralization, we hypothesized that VV are the basis for BCs. To comprehensively investigate this arteriogenesis process, we used high-resolution imaging, including corrosion casts, post-mortem angiography with stereoscopy, micro-CT, and immunohistology, in combination with a novel semi-acute vessel occlusion model. This porcine model was produced by implanting a copper stent minimally invasively into the left anterior descending coronary artery. To define the kinetics of arteriogenesis, pigs (n = 11) were assigned to one of the five euthanasia timepoints: day 0.5 (D0.5, n = 2), D3 (n = 2), D5 (n = 1), D7 (n = 3), or D12 (n = 3) after stent implantation. We found that (1) BCs originate from longitudinally running type 1 VV, mainly VV interna, partially also from VV externa; (2) the growth of VV to BC is rapid, occurring within 7 days; and (3) porcine BCs are likely functionally relevant, considering an observed 102% increase in the number of smooth muscle cell layers in their vascular wall. High-resolution imaging in a minimally invasive non-acute vessel occlusion model is an innovative technique that allowed us to provide direct evidence that porcine BCs develop from the VV. These data may be crucial for further studies on the treatment of angina pectoris and thromboangiitis obliterans through therapeutic stimulation of BC development.