Targeting angiogenesis to restore the microcirculation after reperfused MI

Identification of biomarkers related to angiogenesis in myocardial ischemia-reperfusion injury and prediction of potential drugs

Myocardial ischemia-reperfusion injury (MIRI) refers to the secondary damage to myocardial tissue that occurs when blood perfusion is rapidly restored following myocardial ischemia. This process often exacerbates the injury to myocardial fiber structure and function. The activation mechanism of angiogenesis is closely related to MIRI and plays a significant role in the occurrence and progression of ischemic injury. In this study, we utilized sequencing data from the GEO database and employed WGCNA, Mfuzz cluster analysis, and protein interaction network to identify Stat3, Rela, and Ubb as hub genes involved in MIRI-angiogenesis. Additionally, the GO and KEGG analysis of differentially expressed genes highlighted their broad participation in inflammatory responses and associated signaling pathways. Moreover, the analysis of sequencing data and hub genes revealed a notable increase in the infiltration ratio of monocytes and activated mast cells. By establishing key cell ROC curves, using independent datasets, and validating the expression of hub genes, we demonstrated their high diagnostic value. Moreover, by scrutinizing single-cell sequencing data alongside trajectory analysis, it has come to light that Stat3 and Rela exhibit predominant expression within Dendritic cells. In contrast, Ubb demonstrates expression across multiple cell types, with all three genes being expressed at distinct stages of cellular development. Lastly, leveraging the CMap database, we predicted potential small molecule compounds for the identified hub genes and validated their binding activity through molecular docking. Ultimately, our research provides valuable evidence and references for the early diagnosis and treatment of MIRI from the perspective of angiogenesis.

Application of angiogenesis-related genes associated with immune infiltration in the molecular typing and diagnosis of acute myocardial infarction

BACKGROUND

Angiogenesis has been discovered to be a critical factor in developing tumors and ischemic diseases. However, the role of angiogenesis-related genes (ARGs) in acute myocardial infarction (AMI) remains unclear.

METHODS

The GSE66360 dataset was used as the training cohort, and the GSE48060 dataset was used as the external validation cohort. The random forest (RF) algorithm was used to identify the signature genes. Consensus clustering analysis was used to identify robust molecular clusters associated with angiogenesis. The ssGSEA was used to analyze the correlation between ARGs and immune cell infiltration. In addition, we constructed miRNA-gene, transcription factor network, and targeted drug network of signature genes. RT-qPCR was used to verify the expression levels of signature genes.

RESULTS

Seven signature ARGs were identified based on the RF algorithm. Receiver operating characteristic curves confirmed the classification accuracy of the risk predictive model based on signature ARGs (area under the curve [AUC] = 0.9596 in the training cohort and AUC = 0.7773 in the external validation cohort). Subsequently, the ARG clusters were identified by consensus clustering. Cluster B had a more generalized high expression of ARGs and was significantly associated with immune infiltration. The miRNA and transcription factor network provided new ideas for finding potential upstream targets and biomarkers. Finally, the results of RT-qPCR were consistent with the bioinformatics analysis, further validating our results.

CONCLUSIONS

Angiogenesis is closely related to AMI, and characterizing the angiogenic features of patients with AMI can help to risk-stratify patients and provide personalized treatment.

Ultrasound-targeted microbubble destruction rapidly improves left ventricular function in rats with ischemic cardiac dysfunction

BACKGROUND

Previous studies have demonstrated the efficacy of ultrasound-targeted microbubble destruction (UTMD) in the treatment of ischemic heart failure (HF). The purpose of this study was to explore the mechanism by which UTMD improves ischemic HF.

METHODS

An ischemic heart failure model was established using Sprague-Dawley rats. Rats were randomly divided into 7 groups: sham group, HF group, HF + MB group, HF + ultrasound (US) group, HF + UTMD group, HF + UTMD+LY294002 group, and HF + LY294002 group. Serum BNP level and echocardiographic parameters were measured to evaluate cardiac function. PI3K/Akt/eNOS signaling pathway protein levels were detected by immunohistochemistry (IHC) and western blotting. The concentrations of nitrous oxide (NO) and ATP were detected by ELISA, and hematoxylin and eosin (HE) staining was used to evaluate myocardial tissue.

RESULTS

UTMD rapidly improved ejection fraction (EF) (HF: 37.16 ± 1.21% vs. HF + UTMD: 46.31 ± 3.00%, P < 0.01) and fractional shortening (FS) (HF: 18.53 ± 0.58% vs. HF + UTMD: 24.05 ± 1.84%, P < 0.01) in rats with ischemic HF. UTMD activated the PI3K/AKT/eNOS signaling pathway (HF vs. HF + UTMD, P < 0.01) and promoted the release of NO and ATP (HF vs. HF + UTMD, both, P < 0.05). Inhibition of the PI3K/AKT/eNOS signaling pathway by LY294002 worsened EF (HF: 37.16 ± 1.21% vs. HF + LY294002: 32.73 ± 3.05%, P < 0.05), and the release of NO and ATP by UTMD (HF + UTMD vs. HF + UTMD+LY294002, P < 0.05).

CONCLUSIONS

UTMD can rapidly improve cardiac function in ischemic HF by activating the PI3K/Akt/eNOS signaling pathway and promoting the release of NO and ATP.

Comparison of the preconditioning effect of different exercise training modalities on myocardial ischemia-reperfusion injury

The study of exercise preconditioning can develop strategies to prevent cardiovascular diseases and outline the efficient exercise model. However, the exercise type with the most protective effect against ischemia-reperfusion injury is unknown. In this study, we examined the effects of three kinds of exercise preconditioning on myocardial ischemia-reperfusion in adult rats and explored the possible underlying mechanisms. Male Wistar rats subjected to ten weeks of endurance, resistance, and concurrent training underwent ischemia (30 min) and reperfusion (120 min) induction. Then, infarction size, serum levels of the CK-MB, the redox status, and angiogenesis proteins (VEGF, ANGP-1, and ANGP-2) were measured in the cardiac tissue. Results showed that different exercise training modes have the same reduction effects on infarction size, but ischemia-reperfusion-induced CK-MB was lower in response to endurance training and concurrent training. Furthermore, cardiac VEGF levels increased in all three kinds of exercise preconditioning but ischemia-reperfusion-induced ANGP-1 elevated more in endurance training. The cardiac GPX activity was improved significantly through the resistance and concurrent exercise compared to the endurance exercise. In addition, all three exercise preconditioning models decreased MPO levels, and ischemia reperfusion-induced MDA was lower in endurance and resistance training. Overall, these results indicated that cardioprotection of exercise training against ischemia-reperfusion injury depends on the exercise modality. Cardioprotective effects of aerobic, resistance, and concurrent exercises are due to different mechanisms. The preconditioning effects of endurance training are mediated mainly by pervasive angiogenic responses and resistance training through oxidative stress amelioration. The preconditioning effects of concurrent training rely on both angiogenesis and oxidative stress amelioration.

Health position paper and redox perspectives on reactive oxygen species as signals and targets of cardioprotection

The present review summarizes the beneficial and detrimental roles of reactive oxygen species in myocardial ischemia/reperfusion injury and cardioprotection. In the first part, the continued need for cardioprotection beyond that by rapid reperfusion of acute myocardial infarction is emphasized. Then, pathomechanisms of myocardial ischemia/reperfusion to the myocardium and the coronary circulation and the different modes of cell death in myocardial infarction are characterized. Different mechanical and pharmacological interventions to protect the ischemic/reperfused myocardium in elective percutaneous coronary interventions and coronary artery bypass grafting, in acute myocardial infarction and in cardiotoxicity from cancer therapy are detailed. The second part keeps the focus on ROS providing a comprehensive overview of molecular and cellular mechanisms involved in ischemia/reperfusion injury. Starting from mitochondria as the main sources and targets of ROS in ischemic/reperfused myocardium, a complex network of cellular and extracellular processes is discussed, including relationships with Ca2+ homeostasis, thiol group redox balance, hydrogen sulfide modulation, cross-talk with NAPDH oxidases, exosomes, cytokines and growth factors. While mechanistic insights are needed to improve our current therapeutic approaches, advancements in knowledge of ROS-mediated processes indicate that detrimental facets of oxidative stress are opposed by ROS requirement for physiological and protective reactions. This inevitable contrast is likely to underlie unsuccessful clinical trials and limits the development of novel cardioprotective interventions simply based upon ROS removal.

Endothelial cell dysfunction in cardiac disease: driver or consequence?

The vascular endothelium is a multifunctional cellular system which directly influences blood components and cells within the vessel wall in a given tissue. Importantly, this cellular interface undergoes critical phenotypic changes in response to various biochemical and hemodynamic stimuli, driving several developmental and pathophysiological processes. Multiple studies have indicated a central role of the endothelium in the initiation, progression, and clinical outcomes of cardiac disease. In this review we synthesize the current understanding of endothelial function and dysfunction as mediators of the cardiomyocyte phenotype in the setting of distinct cardiac pathologies; outline existing in vivo and in vitro models where key features of endothelial cell dysfunction can be recapitulated; and discuss future directions for development of endothelium-targeted therapeutics for cardiac diseases with limited existing treatment options.

[68Ga]Ga-NODAGA-E[(cRGDyK)]2 angiogenesis PET following myocardial infarction in an experimental rat model predicts cardiac functional parameters and development of heart failure

BACKGROUND

Angiogenesis has increasingly been a target for imaging and treatment over the last decade. The integrin αvβ3 is highly expressed in cells during angiogenesis and are therefore a promising target for imaging. In this study, we aimed to investigate the PET tracer [68Ga]Ga-RGD as a marker of angiogenesis following MI and its ability to predict cardiac functional parameters.

METHODS

First, the real-time interaction between [68Ga]Ga-RGD and integrin αvβ3 was investigated using surface plasmon resonance (SPR). Second, an animal study was performed to investigate the [68Ga]Ga-RGD uptake in the infarcted area after one and four weeks following MI in a rat model (MI = 68, sham surgery = 36). Finally, the specificity of the [68Ga]Ga-RGD tracer was evaluated ex vivo using histology, autoradiography, gamma counting and flow cytometry.

RESULTS

SPR showed that [68Ga]Ga-RGD has a high affinity for integrin αvβ3, forming a strong and stable binding. PET/CT showed a significantly higher uptake of [68Ga]Ga-RGD in the infarcted area compared to sham one week (p < 0.001) and four weeks (p < 0.001) after MI. The uptake of [68Ga]Ga-RGD after one week correlated to end diastolic volume (r = 0.74, p < 0.001) and ejection fraction (r = - 0.71, p < 0.001) after four weeks.

CONCLUSION

This study demonstrates that [68Ga]Ga-RGD has a high affinity for integrin αvβ3, which enables the evaluation of angiogenesis and remodeling. The [68Ga]Ga-RGD uptake after one week indicates that [68Ga]Ga-RGD may be used as an early predictor of cardiac functional parameters and possible development of heart failure after MI. These encouraging data supports the clinical translation and future use in MI patients.

ANNEXIN A2 FACILITATES NEOVASCULARIZATION TO PROTECT AGAINST MYOCARDIAL INFARCTION INJURY VIA INTERACTING WITH MACROPHAGE YAP AND ENDOTHELIAL INTEGRIN Β3

ABSTRACT

Cardiac macrophages with different polarization phenotypes regulate ventricular remodeling and neovascularization after myocardial infarction (MI). Annexin A2 (ANXA2) promotes macrophage polarization to the repair phenotype and regulates neovascularization. However, whether ANXA2 plays any role in post-MI remodeling and its underlying mechanism remains obscure. In this study, we observed that expression levels of ANXA2 were dynamically altered in mouse hearts upon MI and peaked on the second day post-MI. Using adeno-associated virus vector-mediated overexpression or silencing of ANXA2 in the heart, we also found that elevation of ANXA2 in the infarcted myocardium significantly improved cardiac function, reduced cardiac fibrosis, and promoted peri-infarct angiogenesis, compared with controls. By contrast, reduction of cardiac ANXA2 exhibited opposite effects. Furthermore, using in vitro coculture system, we found that ANXA2-engineered macrophages promoted cardiac microvascular endothelial cell (CMEC) proliferation, migration, and neovascularization. Mechanistically, we identified that ANXA2 interacted with yes-associated protein (YAP) in macrophages and skewed them toward pro-angiogenic phenotype by inhibiting YAP activity. In addition, ANXA2 directly interacted with integrin β3 in CMECs and enhanced their growth, migration, and tubule formation. Our results indicate that increased expression of ANXA2 could confer protection against MI-induced injury by promoting neovascularization in the infarcted area, partly through the inhibition of YAP in macrophages and activation of integrin β3 in endothelial cells. Our study provides new therapeutic strategies for the treatment of MI injury.

Combination human umbilical cord perivascular and endothelial colony forming cell therapy for ischemic cardiac injury

Cell-based therapeutics are promising interventions to repair ischemic cardiac tissue. However, no single cell type has yet been found to be both specialized and versatile enough to heal the heart. The synergistic effects of two regenerative cell types including endothelial colony forming cells (ECFC) and first-trimester human umbilical cord perivascular cells (FTM HUCPVC) with endothelial cell and pericyte properties respectively, on angiogenic and regenerative properties were tested in a rat model of myocardial infarction (MI), in vitro tube formation and Matrigel plug assay. The combination of FTM HUCPVCs and ECFCs synergistically reduced fibrosis and cardiomyocyte apoptosis, while promoting favorable cardiac remodeling and contractility. These effects were in part mediated by ANGPT2, PDGF-β, and VEGF-C. PDGF-β signaling-dependent synergistic effects on angiogenesis were also observed in vitro and in vivo. FTM HUCPVCs and ECFCs represent a cell combination therapy for promoting and sustaining vascularization following ischemic cardiac injury.

Spatial Multiplexed Protein Profiling of Cardiac Ischemia-Reperfusion Injury

BACKGROUND

Reperfusion therapy is critical to myocardial salvage in the event of a myocardial infarction but is complicated by ischemia-reperfusion injury (IRI). Limited understanding of the spatial organization of cardiac cells, which governs cellular interaction and function, has hindered the search for targeted interventions minimizing the deleterious effects of IRI.

METHODS

We used imaging mass cytometry to characterize the spatial distribution and dynamics of cell phenotypes and communities in the mouse left ventricle following IRI. Heart sections were collected from 12 cardiac segments (basal, mid-cavity, apical, and apex of the anterior, lateral, and inferior wall) and 8 time points (before ischemia [I-0H], and postreperfusion [R-0H, R-2H, R-6H, R-12H, R-1D, R-3D, R-7D]), and stained with 29 metal-isotope-tagged antibodies. Cell community analysis was performed on reconstructed images, and the most disease-relevant cell type and target protein were selected for intervention of IRI.

RESULTS

We obtained a total of 251 multiplexed images, and identified 197 063 single cells, which were grouped into 23 distinct cell communities based on the structure of cellular neighborhoods. The cellular architecture was heterogeneous throughout the ventricular wall and exhibited swift changes following IRI. Analysis of proteins with posttranslational modifications in single cells unveiled 13 posttranslational modification intensity clusters and highlighted increased H3K9me3 (tri-methylated lysine 9 of histone H3) as a key regulatory response in endothelial cells during the middle stage of IRI. Erasing H3K9 methylation, by silencing its methyltransferase Suv39h1 or overexpressing its demethylase Kdm4d in isolated endothelial cells, attenuated cardiac dysfunction and pathological remodeling following IRI. in vitro, H3K9me3 binding significantly increased at endothelial cell function-related genes upon hypoxia, suppressing tube formation, which was rescued by inhibiting H3K9me3.

CONCLUSIONS

We mapped the spatiotemporal heterogeneity of cellular phenotypes in the adult heart upon IRI, and uncovered H3K9me3 in endothelial cells as a potential therapeutic target for alleviating pathological remodeling of the heart following myocardial IRI.

MicroRNA-216a is essential for cardiac angiogenesis

While it is experimentally supported that impaired myocardial vascularization contributes to a mismatch between myocardial oxygen demand and supply, a mechanistic basis for disruption of coordinated tissue growth and angiogenesis in heart failure remains poorly understood. Silencing strategies that impair microRNA biogenesis have firmly implicated microRNAs in the regulation of angiogenesis, and individual microRNAs prove to be crucial in developmental or tumor angiogenesis. A high-throughput functional screening for the analysis of a whole-genome microRNA silencing library with regard to their phenotypic effect on endothelial cell proliferation as a key parameter, revealed several anti- and pro-proliferative microRNAs. Among those was miR-216a, a pro-angiogenic microRNA which is enriched in cardiac microvascular endothelial cells and reduced in expression under cardiac stress conditions. miR-216a null mice display dramatic cardiac phenotypes related to impaired myocardial vascularization and unbalanced autophagy and inflammation, supporting a model where microRNA regulation of microvascularization impacts the cardiac response to stress.

Are There Hopeful Therapeutic Strategies to Regenerate the Infarcted Hearts?

Ischemic heart disease remains the primary cause of morbidity and mortality worldwide. Despite significant advancements in pharmacological and revascularization techniques in the late 20th century, heart failure prevalence after myocardial infarction has gradually increased over the last 2 decades. After ischemic injury, pathological remodeling results in cardiomyocytes (CMs) loss and fibrosis, which leads to impaired heart function. Unfortunately, there are no clinical therapies to regenerate CMs to date, and the adult heart's limited turnover rate of CMs hinders its ability to self-regenerate. In this review, we present novel therapeutic strategies to regenerate injured myocardium, including (1) reconstruction of cardiac niche microenvironment, (2) recruitment of functional CMs by promoting their proliferation or differentiation, and (3) organizing 3-dimensional tissue construct beyond the CMs. Additionally, we highlight recent mechanistic insights that govern these strategies and identify current challenges in translating these approaches to human patients.

Myocardial angiogenesis induced by concurrent vitamin D supplementation and aerobic-resistance training is mediated by inhibiting miRNA-15a, and miRNA-146a and upregulating VEGF/PI3K/eNOS signaling pathway

This study aimed to investigate the effects of co-treatment of aerobic-resistance training (ART), vitamin D₃ (VD₃) on cardiovascular function considering the involvement of microRNA-15a and microRNA-146a, vascular endothelial growth factor (VEGF), phosphatidylinositol-3 kinase (PI3K), and endothelial nitric oxide synthase (eNOS) after myocardial infarction (MI) in rats. To induce MI, male Wistar rats subcutaneously received isoproterenol for 2 days, then MI was confirmed by echocardiography. MI rats were divided into six groups (n = 8/group). MI + VD₃, MI + sesame oil (Veh), MI + ART, MI + VD₃ + ART, and MI + Veh + ART, and received the related treatments for 8 weeks. Exercise tests, echocardiography, real-time quantitative polymerase chain reaction (qRT-PCR), western blotting, and histological staining were performed after the end of treatments. The highest ejection fraction (EF%), fractional shortening (FS%), exercise capacity (EC), and maximal load test (MLT) amounts were observed in the groups treated with VD₃, ART, and VD₃ + ART (P < 0.05). These were accompanied by a significantly increased angiogenesis post-MI. Furthermore, the levels of circulating microRNA-15a and microRNA-146a were significantly decreased in these groups compared to MI rats that were together with a significant upregulation of cardiac VEGF, PI3K, and eNOS expression. Overall, the best results were observed in the group treated with VD₃ + ART. Concurrent VD₃ supplementation and ART attenuated microRNA-15a and microRNA-146a and induced angiogenesis via VEGF/PI3K/eNOS axis. This data demonstrate that concurrent VD₃ supplementation and ART is a more efficient strategy than monotherapy to improve cardiac function post-MI.

ADSC-derived exosomes attenuate myocardial infarction injury by promoting miR-205-mediated cardiac angiogenesis

BACKGROUND

Acute myocardial infarction is a major health problem and is the leading cause of death worldwide. Myocardial apoptosis induced by myocardial infarction injury is involved in the pathophysiology of heart failure. Therapeutic stem cell therapy has the potential to be an effective and favorable treatment for ischemic heart disease. Exosomes derived from stem cells have been shown to effectively repair MI injury-induced cardiomyocyte damage. However, the cardioprotective benefits of adipose tissue-derived mesenchymal stem cell (ADSC)-Exos remain unknown. This study aimed to investigate the protective effects of exosomes from ADSC on the hearts of MI-treated mice and to explore the underlying mechanisms.

METHODS

Cellular and molecular mechanisms were investigated using cultured ADSCs. On C57BL/6J mice, we performed myocardial MI or sham operations and assessed cardiac function, fibrosis, and angiogenesis 4 weeks later. Mice were intramyocardially injected with ADSC-Exos or vehicle-treated ADSCs after 25 min following the MI operation.

RESULTS

Echocardiographic experiments showed that ADSC-Exos could significantly improve left ventricular ejection fraction, whereas ADSC-Exos administration could significantly alleviate MI-induced cardiac fibrosis. Additionally, ADSC-Exos treatment has been shown to reduce cardiomyocyte apoptosis while increasing angiogenesis. Molecular experiments found that exosomes extracted from ADSCs can promote the proliferation and migration of microvascular endothelial cells, facilitate angiogenesis, and inhibit cardiomyocytes apoptosis through miRNA-205. We then transferred isolated exosomes from ADSCs into MI-induced mice and observed decreased cardiac fibrosis, increased angiogenesis, and improved cardiac function. We also observed increased apoptosis and decreased expression of hypoxia-inducible factor-1α and vascular endothelial growth factor in HMEC-1 transfected with a miRNA-205 inhibitor.

CONCLUSION

In summary, these findings show that ADSC-Exos can alleviate cardiac injury and promote cardiac function recovery in MI-treated mice via the miRNA-205 signaling pathway. ADSC-Exos containing miRNA205 have a promising therapeutic potential in MI-induced cardiac injury.

The Role of miRNA in the Regulation of Angiogenesis in Ischemic Heart Disease

Despite continued improvements in primary prevention and treatment, ischemic heart disease (IHD) is the most common cause of mortality in both developing and developed countries. Promoting angiogenesis and reconstructing vascular network in ischemic myocardium are critical process of postischemic tissue repair. Effective strategies to promote survival and avoid apoptosis of endothelial cells in the ischemic myocardium can help to achieve long-term cardiac angiogenesis. Therefore, it is of great importance to investigate the molecular pathophysiology of angiogenesis in-depth and to find the key targets that promote angiogenesis. Recently years, many studies have found that microRNAs play important regulatory roles in almost all process of angiogenesis, including vascular sprouting, proliferation, survival and migration of vascular endothelial cells, recruitment of vascular progenitor cells, and control of angiopoietin expression. This review presents detailed information about the regulatory role of miRNAs in the angiogenesis of IHD in recent years, and provides new therapeutic ideas for the treatment of IHD.

Reduction in mitochondrial ROS improves oxidative phosphorylation and provides resilience to coronary endothelium in non-reperfused myocardial infarction

Recent studies demonstrated that mitochondrial antioxidant MnSOD that reduces mitochondrial (mito) reactive oxygen species (ROS) helps maintain an optimal balance between sub-cellular ROS levels in coronary vascular endothelial cells (ECs). However, it is not known whether EC-specific mito-ROS modulation provides resilience to coronary ECs after a non-reperfused acute myocardial infarction (MI). This study examined whether a reduction in endothelium-specific mito-ROS improves the survival and proliferation of coronary ECs in vivo. We generated a novel conditional binary transgenic animal model that overexpresses (OE) mitochondrial antioxidant MnSOD in an EC-specific manner (MnSOD-OE). EC-specific MnSOD-OE was validated in heart sections and mouse heart ECs (MHECs). Mitosox and mito-roGFP assays demonstrated that MnSOD-OE resulted in a 50% reduction in mito-ROS in MHEC. Control and MnSOD-OE mice were subject to non-reperfusion MI surgery, echocardiography, and heart harvest. In post-MI hearts, MnSOD-OE promoted EC proliferation (by 2.4 ± 0.9 fold) and coronary angiogenesis (by 3.4 ± 0.9 fold), reduced myocardial infarct size (by 27%), and improved left ventricle ejection fraction (by 16%) and fractional shortening (by 20%). Interestingly, proteomic and Western blot analyses demonstrated upregulation in mitochondrial complex I and oxidative phosphorylation (OXPHOS) proteins in MnSOD-OE MHECs. These MHECs also showed increased mitochondrial oxygen consumption rate (OCR) and membrane potential. These findings suggest that mito-ROS reduction in EC improves coronary angiogenesis and cardiac function in non-reperfused MI, which are associated with increased activation of OXPHOS in EC-mitochondria. Activation of an energy-efficient mechanism in EC may be a novel mechanism to confer resilience to coronary EC during MI.

HSPA12A Stimulates p38/ERK-AP-1 Signaling to Promote Angiogenesis and Is Required for Functional Recovery Postmyocardial Infarction

Angiogenesis plays a critical role in wound healing postmyocardial infarction (MI). However, there is still a lack of ideal angiogenic therapeutics for rescuing ischemic hearts clinically, suggesting that a more understanding regarding angiogenesis regulation is urgently needed. Heat shock protein A12A (HSPA12A) is an atypical member of the HSP70 family. Here, we demonstrated that HSPA12A was upregulated during endothelial tube formation, a characteristic of in vitro angiogenesis. Intriguingly, overexpression of HSPA12A promoted in vitro angiogenic characteristics including proliferation, migration, and tube formation of endothelial cells. By contrast, deficiency of HSPA12A impaired myocardial angiogenesis and worsened cardiac dysfunction post-MI in mice. The expression of genes related to angiogenesis (VEGF, VEGFR2, and Ang-1) was decreased by HSPA12A deficiency in MI hearts of mice, whereas their expression was increased by HSPA12A overexpression in endothelial cells. HSPA12A overexpression in endothelial cells increased phosphorylation levels and nuclear localization of AP-1, a transcription factor dominating angiogenic gene expression. Also, HSPA12A increased p38 and ERK phosphorylation levels, whereas inhibition of p38 or ERKs diminished the HSPA12A-promoted AP-1 phosphorylation and nuclear localization, as well as VEGF and VEGFR2 expression in endothelial cells. Notably, inhibition of either p38 or ERKs diminished the HSPA12A-promoted in vitro angiogenesis characteristics. The findings identified HSPA12A as a novel angiogenesis activator, and HSPA12A might represent a viable strategy for the management of myocardial healing in patients with ischemic heart diseases.

Shexiang Tongxin Dropping Pills Promote Macrophage Polarization-Induced Angiogenesis Against Coronary Microvascular Dysfunction via PI3K/Akt/mTORC1 Pathway

Background: Accumulating evidence suggests that coronary microvascular dysfunction (CMD) is one of the important causes of coronary artery diseases. Angiogenesis can effectively improve CMD by increasing blood supply capacity, recovering cardiac function and poor hemodynamics. Clinical studies have approved Shexiang Tongxin dropping pill (STDP), which has exerted remarkable roles on ameliorating CMD, but the effects and mechanisms of STDPs on angiogenesis have not been clarified. Purpose: The purpose of this study was to elucidate the effects and potential mechanisms of STDPs on macrophage polarization-induced angiogenesis against CMD. Methods: Echocardiography, optical microangiography (OMAG), and histological examination were applied to evaluate cardioprotection and proangiogenic effects of STDPs on left anterior descending (LAD) ligation-induced CMD rats. In vitro, oxygen-glucose deprivation-reperfusion (OGD/R)-induced HUVEC model and LPS-stimulated bone marrow-derived macrophage (BMDM) model were established to observe the effects of STDPs on angiogenesis and M2 macrophage polarization. Results: STDPs improved cardiac function, increased microvascular density, and the number of M2 macrophages in the heart of CMD rats. In vitro, STDPs accelerated the proliferation, migration, and tube formation in OGD/R-induced HUVECs similar to the effects of VEGF-A. Furthermore, in LPS-stimulated BMDMs model, STDPs modulated M2 macrophage polarization and increased VEGF-A release via the PI3K/AKT/mTORC1 pathway. Conclusion: STDPs promoted macrophage polarization-induced angiogenesis against CMD via the PI3K/Akt/mTORC1 pathway. Our results demonstrated that the phenotype transformation of macrophages and stimulating the secretion of VEGF-A may be applied as novel cardioprotective targets for the treatment of CMD.

Endothelial Transient Receptor Potential Canonical Channel Regulates Angiogenesis and Promotes Recovery After Myocardial Infarction

Background

Transient receptor potential canonical (TRPC) channels play a role in angiogenesis. However, the involvement of TRPC1 in myocardial infarction (MI) remains unclear. The present study was aimed at investigating whether TRPC1 can improve the recovery of cardiac function via prompting angiogenesis following MI.

Methods and Results

In vitro, coronary artery endothelial cells from floxed TRPC1 mice and endothelial cell‐specific TRPC1 channel knockout mice were cultured to access EC angiogenesis. Both EC tube formation and migration were significantly suppressed in mouse coronary artery endothelial cells from endothelial cell‐specific TRPC1 channel knockout mice. In vivo, coronary artery endothelial cells from floxed TRPC1 and endothelial cell‐specific TRPC1 channel knockout mice were subjected to MI, then echocardiography, triphenyltetrazolium chloride staining and immunofluorescence were performed to assess cardiac repair on day 28. Endothelial cell‐specific TRPC1 channel knockout mice had higher ejection fraction change, larger myocardial infarct size, and reduced capillary density in the infarct area compared with coronary artery endothelial cells from floxed TRPC1 mice. Furthermore, we found underlying regulation by HIF‐1α (hypoxic inducible factor‐1α) and MEK‐ERK (mitogen‐activated protein kinase/extracellular signal‐regulated kinase) that could be the mechanism for the angiogenetic action of TRPC1. Significantly, treatment with dimethyloxaloylglycine, an activator of HIF‐1α, induced cardiac improvement via the HIF‐1α‐TRPC1‐MEK/ERK pathway in MI mice.

Conclusions

Our study demonstrated TRPC1 improves cardiac function after MI by increasing angiogenesis via the upstream regulator HIF‐1α and downstream MEK/ERK, and dimethyloxaloylglycine treatment has protective effect on MI through the HIF‐1α‐TRPC1‐MEK/ERK pathway.

Computational simulations of the 4D micro-circulatory network in zebrafish tail amputation and regeneration

Wall shear stress (WSS) contributes to the mechanotransduction underlying microvascular development and regeneration. Using computational fluid dynamics, we elucidated the interplay between WSS and vascular remodelling in a zebrafish model of tail amputation and regeneration. The transgenic Tg (fli1:eGFP; Gata1:ds-red) zebrafish line was used to track the three-dimensional fluorescently labelled vascular endothelium for post-image segmentation and reconstruction of the fluid domain. Particle image velocimetry was used to validate the blood flow. Following amputation to the dorsal aorta and posterior cardinal vein (PCV), vasoconstriction developed in the dorsal longitudinal anastomotic vessel (DLAV) along with increased WSS in the proximal segmental vessels (SVs) from amputation. Angiogenesis ensued at the tips of the amputated DLAV and PCV where WSS was minimal. At 2 days post amputation (dpa), vasodilation occurred in a pair of SVs proximal to amputation, followed by increased blood flow and WSS; however, in the SVs distal to amputation, WSS normalized to the baseline. At 3 dpa, the blood flow increased in the arterial SV proximal to amputation and through anastomosis with DLAV formed a loop with PCV. Thus, our in silico modelling revealed the interplay between WSS and microvascular adaptation to changes in WSS and blood flow to restore microcirculation following tail amputation.

Computational simulations of the 4D micro-circulatory network in zebrafish tail amputation and regeneration

Wall shear stress (WSS) contributes to the mechanotransduction underlying microvascular development and regeneration. Using computational fluid dynamics, we elucidated the interplay between WSS and vascular remodelling in a zebrafish model of tail amputation and regeneration. The transgenic Tg (fli1:eGFP; Gata1:ds-red) zebrafish line was used to track the three-dimensional fluorescently labelled vascular endothelium for post-image segmentation and reconstruction of the fluid domain. Particle image velocimetry was used to validate the blood flow. Following amputation to the dorsal aorta and posterior cardinal vein (PCV), vasoconstriction developed in the dorsal longitudinal anastomotic vessel (DLAV) along with increased WSS in the proximal segmental vessels (SVs) from amputation. Angiogenesis ensued at the tips of the amputated DLAV and PCV where WSS was minimal. At 2 days post amputation (dpa), vasodilation occurred in a pair of SVs proximal to amputation, followed by increased blood flow and WSS; however, in the SVs distal to amputation, WSS normalized to the baseline. At 3 dpa, the blood flow increased in the arterial SV proximal to amputation and through anastomosis with DLAV formed a loop with PCV. Thus, our in silico modelling revealed the interplay between WSS and microvascular adaptation to changes in WSS and blood flow to restore microcirculation following tail amputation.

Differential action of pro-angiogenic and anti-angiogenic components of Danhong injection in ischemic vascular disease or tumor models

OBJECTIVE

We investigate the chemical basis and mechanism of angiogenesis regulation by a multicomponent Chinese medicine Danhong injection (DHI).

METHODS

DHI was fractionated and screened for angiogenesis activities by in vitro tube formation and migration assays. The composition of DHI components was determined by UPLC. The effects of the main active monomers on angiogenesis-related gene and protein expression in endothelial cells were determined by qPCR and Western blotting analyses. Mouse hind limb ischemia and tumor implant models were used to verify the angiogenesis effects in vivo by Laser Doppler and bioluminescent imaging, respectively.

RESULTS

Two distinct chemical components, one promoting (pro-angiogenic, PAC) and the other inhibiting (anti-angiogenic, AAC) angiogenesis, were identified in DHI. PAC enhanced angiogenesis and improved recovery of ischemic limb perfusion while AAC reduced Lewis lung carcinoma growth in vivo in VEGFR-2-Luc mice. Among the PAC or AAC monomers, caffeic acid and rosmarinic acid upregulated TSP1 expression and downregulated KDR and PECAM expression. Caffeic acid and rosmarinic acid significantly decreased while protocatechuic aldehyde increased CXCR4 expression, which are consistent with their differential effects on EC migration.

CONCLUSIONS

DHI is capable of bi-directional regulation of angiogenesis in disease-specific manner. The pro-angiogenesis activity of DHI promotes the repair of ischemic vascular injury, whereas the anti-angiogenesis activity inhibits tumor growth. The active pro- and anti-angiogenesis activities are composed of unique chemical combinations that differentially regulate angiogenesis-related gene networks.

Targeting angiogenesis in myocardial infarction: Novel therapeutics (Review)

Acute myocardial infarction (AMI) remains the main cause of mortality worldwide. Despite surgery and medical treatment, the non-regeneration of dead cardiomyocytes and the limited contractile ability of scar tissue can lead to heart failure. Therefore, restoring blood flow in the infarcted area is important for the repair of myocardial injury. The objective of the present review was to summarize the factors influencing angiogenesis after AMI, and to describe the application of angiogenesis for cardiac repair. Collectively, this review may be helpful for relevant studies and to provide insight into future therapeutic applications in clinical practice.

miR-124 promotes apoptosis and inhibits the proliferation of vessel endothelial cells through P38/MAPK and PI3K/AKT pathways, making it a potential mechanism of vessel endothelial injury in acute myocardial infarction

Due to its rapid onset and high rates of fatality, acute myocardial infarction (AMI) has long been one of the most fatal diseases among all types of heart diseases. Therefore, intensive research efforts have been focused on understanding AMI's potential pathogenesis to seek effective treatment options. In the present study, 20 peripheral blood samples were collected from patients with AMI, after which reverse transcription-quantitative PCR analysis revealed that microRNA (miR)-124 levels in the peripheral blood of patients with AMI was significantly elevated compared with that in the control group. In vitro, a model using pcDNA3.1-miR-124 transfected human umbilical vein endothelial cells (HUVECs) indicated that overexpression of miR-124 could significantly promote the apoptosis and suppress the proliferation of HUVECs using flow cytometry, TUNEL assay and Cell Counting Kit-8 assays. Based on the present findings, RNA samples of HUVECs overexpressing miR-124 was extracted and sequenced to explore the gene expression profile after miR-124 overexpression. Gene Set Enrichment Analysis (GSEA) analysis revealed that the downregulated genes were mainly enriched in signaling pathways, such as PI3K-AKT, whilst the upregulated genes were mainly enriched in metabolism-related signaling pathways, such as the metabolism of xenobiotics by cytochrome P450 pathway. Additionally, Rideogram software was used to determine the chromosomal localization of the differentially expressed genes. The results demonstrated that they were distributed on all chromosomes except for chromosome Y. In addition, characteristic profiles of the differentially expressed genes caused by miR-124 overexpression were analyzed using Connectivity Map. In total, two medicines, anisomycin and sanguinarine, which function as p38/MAPK signaling agonists that can inhibit angiogenesis, presented with the highest enrichment scores. Together with the GSEA results, which indicated that the differentially expressed genes were mainly enriched in the angiogenesis-inhibiting PI3K/AKT signaling pathway, the present study reported that high expression of miR-124 was negatively associated with patients with AMI, promoting the apoptosis and suppressing the proliferation of vessel endothelial cells.

Dynamic resistance exercise increases skeletal muscle-derived FSTL1 inducing cardiac angiogenesis via DIP2A-Smad2/3 in rats following myocardial infarction

PURPOSE

The aim of this study was to investigate the potential of dynamic resistance exercise to generate skeletal muscle-derived follistatin like-1 (FSTL1), which may induce cardioprotection in rats following myocardial infarction (MI) by inducing angiogenesis.

METHODS

Male, adult Sprague-Dawley rats were randomly divided into 5 groups (n = 12 in each group): sham group (S), sedentary MI group (MI), MI + resistance exercise group (MR), MI + adeno-associated virus (AAV)-FSTL1 injection group (MA), and MI + AAV-FSTL1 injection + resistance exercise group (MAR). The AAV-FSTL1 vector was prepared by molecular biology methods and injected into the anterior tibialis muscle. The MI model was established by ligation of the left anterior descending coronary artery. Rats in the MR and MAR groups underwent 4 weeks of dynamic resistance exercise training using a weighted climbing-up ladder. Heart function was evaluated by hemodynamic measures. Collagen volume fraction of myocardium was observed and analyzed by Masson's staining. Human umbilical vein vessel endothelial cells culture and recombinant human FSTL1 protein or transforming growth factor-β receptor 1 (TGFβR1) inhibitor treatment were used to elucidate the molecular signaling mechanism of FSTL1. Angiogenesis, cell proliferation, and disco interacting protein 2 homolog A (DIP2A) location were observed by immunofluorescence staining. The expression of FSTL1, DIP2A, and the activation of signaling pathways were detected by Western blotting. Angiogenesis of endothelial cells was observed by tubule experiment. One-way analysis of variance and Student's t test were used for statistical analysis.

RESULTS

Resistance exercise stimulated the secretion of skeletal muscle FSTL1, which promoted myocardial angiogenesis, inhibited pathological remodeling, and protected cardiac function in MI rats. Exercise facilitated skeletal muscle FSTL1 to play a role in protecting the heart. Exogenous FSTL1 promoted the human umbilical vein vessel endothelial cells proliferation and up-regulated the expression of DIP2A, while TGFβR1 inhibitor intervention down-regulated the phosphorylation level of Smad2/3 and the expression of vascular endothelial growth factor-A, which was not conducive to angiogenesis. FSTL1 bound to the receptor, DIP2A, to regulate angiogenesis mainly through the Smad2/3 signaling pathway. FSTL1-DIP2A directly activated Smad2/3 and was not affected by TGFβR1.

CONCLUSION

Dynamic resistance exercise stimulates the expression of skeletal muscle-derived FSTL1, which could supplement the insufficiency of cardiac FSTL1 and promote cardiac rehabilitation through the DIP2A-Smad2/3 signaling pathway in MI rats.

Ultrasound-Targeted Microbubble Destruction Accelerates Angiogenesis and Ameliorates Left Ventricular Dysfunction after Myocardial Infarction in Mice

Failure of coronary recanalization within 12 h or no flow in the myocardium after percutaneous coronary intervention is associated with high mortality from myocardial infarction, and insufficient angiogenesis in the border zone results in the expansion of infarct area. In this study, we examined the effects of ultrasound-targeted microbubble destruction (UTMD) on angiogenesis and left ventricular dysfunction in a mouse model of myocardial infarction. Fifty-four mice with MI were treated with no UTMD, ultrasound (US) alone or UTMD four times (days 1, 3, 5 and 7), and another 18 mice underwent sham operation and therapy. Therapeutic US was generated with a linear transducer connected to a commercial diagnostic US system (VINNO70). UTMD was performed with the VINNO70 at a peak negative pressure of 0.8 MPa and lipid microbubbles. Transthoracic echocardiography was performed on the first and seventh days. The results indicated that UTMD decreased the infarct size ratio from 78.1 ± 5.3% (untreated) to 43.3 ± 6.4%, accelerated angiogenesis and ameliorated left ventricular dysfunction. The ejection fraction increased from 25.05 ± 8.52% (untreated) to 42.83 ± 9.44% (UTMD). Compared with that in other groups, expression of vascular endothelial growth factor and endothelial nitric oxide synthase and release of nitric oxide were significantly upregulated after UTMD treatment, indicating angiogenesis. Therefore, UTMD is a potential physical approach in the treatment of myocardial infarction.

Gastrin exerts a protective effect against myocardial infarction via promoting angiogenesis

Background

It is known that increased gastrin concentration is negatively correlated with cardiovascular mortality, and plasma gastrin levels are increased in patients after myocardial infarction (MI). However, whether gastrin can play a protective role in MI remains unknown.

Methods

Adult C57BL/6 mice were subjected to ligation of the left anterior descending coronary artery (LAD) and subcutaneous infusion of gastrin (120 μg/Kg body weight/day, 100 μL in the pump) for 28 days after MI. Plasma gastrin concentrations were measured through an ELISA detection kit. Mice were analyzed by echocardiography after surgery. CD31 and VEGF expression were quantified using immunofluorescence staining or/and western blot to assess the angiogenesis in peri-infarct myocardium. Capillary-like tube formation and cell migration assays were performed to detect gastrin-induced angiogenesis.

Results

We found that gastrin administration significantly ameliorated MI-induced cardiac dysfunction and reduced fibrosis at 28 days in post-MI hearts. Additionally, gastrin treatment significantly decreased cardiomyocyte apoptosis and increased angiogenesis in the infarct border zone without influencing cardiomyocyte proliferation. In vitro results revealed that gastrin up-regulated the PI3K/Akt/vascular endothelial growth factor (VEGF) signaling pathway and promoted migration and tube formation of human coronary artery endothelial cells (HCAECs). Cholecystokinin 2 receptor (CCK₂R) mediated the protective effect of gastrin since the CCK₂R blocker CI988 attenuated the gastrin-mediated angiogenesis and cardiac function protection.

Conclusion

Our data revealed that gastrin promoted angiogenesis and improved cardiac function in post-MI mice, highlighting its potential as a therapeutic target candidate.

Gastrin mediates cardioprotection through angiogenesis after myocardial infarction by activating the HIF-1α/VEGF signalling pathway

Acute myocardial infarction (MI) is one of the leading causes of death in humans. Our previous studies showed that gastrin alleviated acute myocardial ischaemia-reperfusion injury. We hypothesize that gastrin might protect against heart injury after MI by promoting angiogenesis. An MI model was simulated by ligating the anterior descending coronary artery in adult male C57BL/6J mice. Gastrin was administered twice daily by intraperitoneal injection for 2 weeks after MI. We found that gastrin reduced mortality, improved myocardial function with reduced infarct size and promoted angiogenesis. Gastrin increased HIF-1α and VEGF expression. Downregulation of HIF-1α expression by siRNA reduced the proliferation, migration and tube formation of human umbilical vein endothelial cells. These results indicate that gastrin restores cardiac function after MI by promoting angiogenesis via the HIF-1α/VEGF pathway.

Long-Term Severe In Vitro Hypoxia Exposure Enhances the Vascularization Potential of Human Adipose Tissue-Derived Stromal Vascular Fraction Cell Engineered Tissues

The therapeutic potential of mesenchymal stromal/stem cells (MSC) for treating cardiac ischemia strongly depends on their paracrine-mediated effects and their engraftment capacity in a hostile environment such as the infarcted myocardium. Adipose tissue-derived stromal vascular fraction (SVF) cells are a mixed population composed mainly of MSC and vascular cells, well known for their high angiogenic potential. A previous study showed that the angiogenic potential of SVF cells was further increased following their in vitro organization in an engineered tissue (patch) after perfusion-based bioreactor culture. This study aimed to investigate the possible changes in the cellular SVF composition, in vivo angiogenic potential, as well as engraftment capability upon in vitro culture in harsh hypoxia conditions. This mimics the possible delayed vascularization of the patch upon implantation in a low perfused myocardium. To this purpose, human SVF cells were seeded on a collagen sponge, cultured for 5 days in a perfusion-based bioreactor under normoxia or hypoxia (21% and <1% of oxygen tension, respectively) and subcutaneously implanted in nude rats for 3 and 28 days. Compared to ambient condition culture, hypoxic tension did not alter the SVF composition in vitro, showing similar numbers of MSC as well as endothelial and mural cells. Nevertheless, in vitro hypoxic culture significantly increased the release of vascular endothelial growth factor (p < 0.001) and the number of proliferating cells (p < 0.00001). Moreover, compared to ambient oxygen culture, exposure to hypoxia significantly enhanced the vessel length density in the engineered tissues following 28 days of implantation. The number of human cells and human proliferating cells in hypoxia-cultured constructs was also significantly increased after 3 and 28 days in vivo, compared to normoxia. These findings show that a possible in vivo delay in oxygen supply might not impair the vascularization potential of SVF- patches, which qualifies them for evaluation in a myocardial ischemia model.

Platelet derived growth factor-A (Pdgf-a) gene transfer modulates scar composition and improves left ventricular function after myocardial infarction

BACKGROUND

Novel therapies that can limit or reverse damage caused by myocardial infarction (MI) could ease the increasing burden of heart failure. In this regard Platelet Derived Growth Factor (PDGF) has been previously shown to contribute to cardiac repair after MI. Here, we use a rodent model of MI and recombinant adeno-associated virus 9 (rAAV9)-mediated gene transfer to overexpress Pdgf-a in the injured heart and assess its therapeutic potential.

METHODS AND RESULTS

Sprague Dawley rats underwent temporary occlusion of the left anterior descending coronary artery, followed immediately by systemic delivery of 1 × 10^11 vector genomes of either rAAV9 Pdgf-a or rAAV9 Empty vector (control). At day 28 post-MI echocardiography showed significantly improved left ventricular (LV) function (fractional shortening) after rAAV9 Pdgf-a (0.394 ± 0.019%) treatment vs control (0.304 ± 0.018%). Immunohistochemical analysis demonstrated significantly increased capillary and arteriolar density in the infarct border zone of rAAV9 Pdgf-a treated hearts together with a significant reduction in infarct scar size (rAAV9 Pdgf-a 6.09 ± 0.94% vs Empty 12.45 ± 0.92%). Western blot and qPCR analyses confirmed overexpression of PDGF-A and showed upregulation of smooth muscle alpha actin (Acta2), collagen type III alpha 1 (Col3a1) and lysyl oxidase (Lox) genes in rAAV9 Pdgf-a treated infarcts.

CONCLUSION

Overexpression of Pdgf-a in the post-MI heart can modulate scar composition and improve LV function. Our study highlights the potential of rAAV gene transfer of Pdgf-a as a cardio-reparative therapy.

The effect of immune cell-derived exosomes in the cardiac tissue repair after myocardial infarction: Molecular mechanisms and pre-clinical evidence

After a myocardial infarction (MI), the inflammatory responses are induced and assist to repair ischaemic injury and restore tissue integrity, but excessive inflammatory processes promote abnormal cardiac remodelling and progress towards heart failure. Thus, a timely resolution of inflammation and a firmly regulated balance between regulatory and inflammatory mechanisms can be helpful. Molecular- and cellular-based approaches modulating immune response post-MI have emerged as a promising therapeutic strategy. Exosomes are essential mediators of cell-to-cell communications, which are effective in modulating immune responses and immune cells following MI, improving the repair process of infarcted myocardium and maintaining ventricular function via the crosstalk among immune cells or between immune cells and myocardial cells. The present review aimed to seek the role of immune cell-secreted exosomes in infarcted myocardium post-MI, together with mechanisms behind their repairing impact on the damaged myocardium. The exosomes we focus on are secreted by classic immune cells including macrophages, dendritic cells, regulatory T cells and CD4+ T cells; however, further research is demanded to determine the role of exosomes secreted by other immune cells, such as B cells, neutrophils and mast cells, in infarcted myocardium after MI. This knowledge can assist in the development of future therapeutic strategies, which may benefit MI patients.

Effect of snail mucus on angiogenesis during wound healing

Background: Angiogenesis is the process through which new blood vessels are formed from existing ones. This process plays an important role in supplying the oxygen and nutrients needed for cellular metabolism and eliminating cell debris during wound healing. Snail mucus can bind to several factors that stimulate angiogenesis, including vascular endothelial growth factor, platelet-derived growth factor, and fibroblast growth factor. The aim of this study is to observe changes in angiogenesis during the healing of wounds topically applied with snail mucus. Methods: Punch biopsy was performed on the back of male Wistar rats to obtain four wounds, and different concentrations of snail mucus were applied to each of these wounds. The animals were sacrificed on days 2, 4, and 7 to observe the extent of angiogenesis during wound healing by microscopy. Results: Two-way ANOVA showed differences in number of blood vessels formed (p = 0.00) and day of observation (p = 0.00) between groups. Post hoc Tukey's HSD test showed that 24% snail mucus treatment does not significantly affect wound healing (p = 0.488); by contrast, treatment with 48% and 96% snail mucus demonstrated significant effects on angiogenesis (p = 0.01). Spearman's test showed interactive effects between snail mucus concentration and day of observation on the extent of angiogenesis (p = 0.001, R = 0.946). Conclusion: Topical application of snail mucus gel can increase angiogenesis during wound healing in Wistar rat skin.

A Brief Review on the Biology and Effects of Cellular and Circulating microRNAs on Cardiac Remodeling after Infarction

Despite advances in diagnostic, prognostic, and treatment modalities, myocardial infarction (MI) remains a leading cause of morbidity and mortality. Impaired cellular signaling after an MI causes maladaptive changes resulting in cardiac remodeling. MicroRNAs (miRNAs/miR) along with other molecular components have been investigated for their involvement in cellular signaling in the pathogenesis of various cardiac conditions like MI. miRNAs are small non-coding RNAs that negatively regulate gene expression. They bind to complementary mRNAs and regulate the rate of protein synthesis by altering the stability of their targeted mRNAs. A single miRNA can modulate several cellular signaling pathways by targeting hundreds of mRNAs. This review focuses on the biogenesis and beneficial effects of cellular and circulating (exosomal) miRNAs on cardiac remodeling after an MI. Particularly, miR-1, -133, 135, and -29 that play an essential role in cardiac remodeling after an MI are described in detail. The limitations that will need to be addressed in the future for the further development of miRNA-based therapeutics for cardiovascular conditions will also be discussed.

H2S Pretreatment Is Promigratory and Decreases Ischemia/Reperfusion Injury in Human Microvascular Endothelial Cells

Endothelial cell injury and vascular function strongly correlate with cardiac function following ischemia/reperfusion injury. Several studies indicate that endothelial cells are more sensitive to ischemia/reperfusion compared to cardiomyocytes and are critical mediators of cardiac ischemia/reperfusion injury. H₂S is involved in the regulation of cardiovascular system homeostasis and can act as a cytoprotectant during ischemia/reperfusion. Activation of ERK1/2 in endothelial cells after H₂S stimulation exerts an enhancement of angiogenesis while its inhibition significantly decreases H₂S cardioprotective effects. In this work, we investigated how H₂S pretreatment for 24 hours prevents the ischemia/reperfusion injury and promotes angiogenesis on microvascular endothelial cells following an ischemia/reperfusion protocol in vitro, using a hypoxic chamber and ischemic buffer to simulate the ischemic event. H₂S preconditioning positively affected cell viability and significantly increased endothelial cell migration when treated with 1 μM H₂S. Furthermore, mitochondrial function was preserved when cells were preconditioned. Since ERK1/2 phosphorylation was extremely enhanced in ischemia/reperfusion condition, we inhibited ERK both directly and indirectly to verify how H₂S triggers this pathway in endothelial cells. Taken together, our data suggest that H₂S treatment 24 hours before the ischemic insult protects endothelial cells from ischemia/reperfusion injury and eventually decreases myocardial injury.

A New Therapeutic Candidate for Cardiovascular Diseases: Berberine

Cardiovascular diseases (CVD) are the leading cause of death in the world. However, due to the limited effectiveness and potential adverse effects of current treatments, the long-term prognosis of CVD patients is still discouraging. In recent years, several studies have found that berberine (BBR) has broad application prospects in the prevention and treatment of CVD. Due to its effectiveness and safety for gastroenteritis and diarrhea caused by bacterial infections, BBR has been widely used in China and other Asian countries since the middle of the last century. The development of pharmacology also provides evidence for the multi-targets of BBR in treating CVD. Researches on CVD, such as arrhythmia, atherosclerosis, dyslipidemia, hypertension, ischemic heart disease, myocarditis and cardiomyopathy, heart failure, etc., revealed the cardiovascular protective mechanisms of BBR. This review systematically summarizes the pharmacological research progress of BBR in the treatment of CVD in recent years, confirming that BBR is a promising therapeutic option for CVD.

The Role of Epoxyeicosatrienoic Acids in Cardiac Remodeling

Epoxyeicosatrienoic acids (EETs) are metabolites of arachidonic acid by cytochrome P450 (CYP) epoxygenases, which include four regioisomers: 5,6-EET, 8,9-EET, 11,12-EET, and 14,15-EET. Each of them possesses beneficial effects against inflammation, fibrosis, and apoptosis, which could combat cardiovascular diseases. Numerous studies have demonstrated that elevation of EETs by overexpression of CYP2J2, inhibition of sEH, or treatment with EET analogs showed protective effects in various cardiovascular diseases, including hypertension, myocardial infarction, and heart failure. As is known to all, cardiac remodeling is the major pathogenesis of cardiovascular diseases. This review will begin with the introduction of EETs and their protective effects in cardiovascular diseases. In the following, the roles of EETs in cardiac remodeling, with a particular emphasis on myocardial hypertrophy, apoptosis, fibrosis, inflammation, and angiogenesis, will be summarized. Finally, it is suggested that upregulation of EETs is a potential therapeutic strategy for cardiovascular diseases. The EET-related drug development against cardiac remodeling is also discussed, including the overexpression of CYP2J2, inhibition of sEH, and the analogs of EET.

Effect of captopril on post-infarction remodelling visualized by light sheet microscopy and echocardiography

Angiotensin converting enzyme inhibitors, among them captopril, improve survival following myocardial infarction (MI). The mechanisms of captopril action remain inadequately understood due to its diverse effects on multiple signalling pathways at different time periods following MI. Here we aimed to establish the role of captopril in late-stage post-MI remodelling. Left anterior descending artery (LAD) ligation or sham surgery was carried out in male C57BL/6J mice. Seven days post-surgery LAD ligated mice were allocated to daily vehicle or captopril treatment continued over four weeks. To provide comprehensive characterization of the changes in mouse heart following MI a 3D light sheet imaging method was established together with automated image analysis workflow. The combination of echocardiography and light sheet imaging enabled to assess cardiac function and the underlying morphological changes. We show that delayed captopril treatment does not affect infarct size but prevents left ventricle dilation and hypertrophy, resulting in improved ejection fraction. Quantification of lectin perfused blood vessels showed improved vascular density in the infarct border zone in captopril treated mice in comparison to vehicle dosed control mice. These results validate the applicability of combined echocardiographic and light sheet assessment of drug mode of action in preclinical cardiovascular research.

Platelet-derived growth factor-AB improves scar mechanics and vascularity after myocardial infarction

Therapies that target scar formation after myocardial infarction (MI) could prevent ensuing heart failure or death from ventricular arrhythmias. We have previously shown that recombinant human platelet-derived growth factor-AB (rhPDGF-AB) improves cardiac function in a rodent model of MI. To progress clinical translation, we evaluated rhPDGF-AB treatment in a clinically relevant porcine model of myocardial ischemia-reperfusion. Thirty-six pigs were randomized to sham procedure or balloon occlusion of the proximal left anterior descending coronary artery with 7-day intravenous infusion of rhPDGF-AB or vehicle. One month after MI, rhPDGF-AB improved survival by 40% compared with vehicle, and cardiac magnetic resonance imaging showed left ventricular (LV) ejection fraction improved by 11.5%, driven by reduced LV end-systolic volumes. Pressure volume loop analyses revealed improved myocardial contractility and energetics after rhPDGF-AB treatment with minimal effect on ventricular compliance. rhPDGF-AB enhanced angiogenesis and increased scar anisotropy (high fiber alignment) without affecting overall scar size or stiffness. rhPDGF-AB reduced inducible ventricular tachycardia by decreasing heterogeneity of the ventricular scar that provides a substrate for reentrant circuits. In summary, we demonstrated that rhPDGF-AB promotes post-MI cardiac wound repair by altering the mechanics of the infarct scar, resulting in robust cardiac functional improvement, decreased ventricular arrhythmias, and improved survival. Our findings suggest a strong translational potential for rhPDGF-AB as an adjunct to current MI treatment and possibly to modulate scar in other organs.

Injectable Drug-Releasing Microporous Annealed Particle Scaffolds for Treating Myocardial Infarction

Intramyocardial injection of hydrogels offers great potential for treating myocardial infarction (MI) in a minimally invasive manner. However, traditional bulk hydrogels generally lack microporous structures to support rapid tissue ingrowth and biochemical signals to prevent fibrotic remodeling toward heart failure. To address such challenges, a novel drug-releasing microporous annealed particle (drugMAP) system is developed by encapsulating hydrophobic drug-loaded nanoparticles into microgel building blocks via microfluidic manufacturing. By modulating nanoparticle hydrophilicity and pregel solution viscosity, drugMAP building blocks are generated with consistent and homogeneous encapsulation of nanoparticles. In addition, the complementary effects of forskolin (F) and Repsox (R) on the functional modulations of cardiomyocytes, fibroblasts, and endothelial cells in vitro are demonstrated. After that, both hydrophobic drugs (F and R) are loaded into drugMAP to generate FR/drugMAP for MI therapy in a rat model. The intramyocardial injection of MAP gel improves left ventricular functions, which are further enhanced by FR/drugMAP treatment with increased angiogenesis and reduced fibrosis and inflammatory response. This drugMAP platform represents a new generation of microgel particles for MI therapy and will have broad applications in regenerative medicine and disease therapy.

Endothelial cell HSPA12B and yes-associated protein cooperatively regulate angiogenesis following myocardial infarction

Angiogenesis is essential for cardiac functional recovery after myocardial infarction (MI). HSPA12B is predominately expressed in endothelial cells and required for angiogenesis. Yes-associated protein (YAP) plays an important role in tumor angiogenesis. This study investigated the cooperative role of HSPA12B and YAP in angiogenesis after MI. Silencing of either HSPA12B or YAP impaired hypoxia-promoted endothelial cell proliferation and angiogenesis. Deficiency of HSPA12B suppressed YAP expression and nuclear translocation after hypoxia. Knockdown of YAP attenuated hypoxia-stimulated HSPA12B nuclear translocation and abrogated HSPA12B-promoted endothelial cell angiogenesis. Mechanistically, hypoxia induced an interaction between endothelial HSPA12B and YAP. ChIP assay showed that HSPA12B is a target gene of YAP/transcriptional enhanced associated domain 4 (TEAD4) and a coactivator in YAP-associated angiogenesis. In vivo studies using the MI model showed that endothelial cell-specific deficiency of HSPA12B (eHspa12b-/-) or YAP (eYap-/-) impaired angiogenesis and exacerbated cardiac dysfunction compared with WT mice. MI increased YAP expression and nuclear translocation in WT hearts but not eHspa12b-/- hearts. HSPA12B expression and nuclear translocation were upregulated in WT MI hearts but not eYap-/- MI myocardium. Our data demonstrate that endothelial HSPA12B is a target and coactivator for YAP/TEAD4 and cooperates with YAP to regulate endothelial angiogenesis after MI.

Histological Validation of Cardiovascular Magnetic Resonance T1 Mapping for Assessing the Evolution of Myocardial Injury in Myocardial Infarction: An Experimental Study

Objective

To determine whether T1 mapping could monitor the dynamic changes of injury in myocardial infarction (MI) and be histologically validated.

Materials and Methods

In 22 pigs, MI was induced by ligating the left anterior descending artery and they underwent serial cardiovascular magnetic resonance examinations with modified Look-Locker inversion T1 mapping and extracellular volume (ECV) computation in acute (within 24 hours, n = 22), subacute (7 days, n = 13), and chronic (3 months, n = 7) phases of MI. Masson's trichrome staining was performed for histological ECV calculation. Myocardial native T1 and ECV were obtained by region of interest measurement in infarcted, peri-infarct, and remote myocardium.

Results

Native T1 and ECV in peri-infarct myocardium differed from remote myocardium in acute (1181 ± 62 ms vs. 1113 ± 64 ms, p = 0.002; 24 ± 4% vs. 19 ± 4%, p = 0.031) and subacute phases (1264 ± 41 ms vs. 1171 ± 56 ms, p < 0.001; 27 ± 4% vs. 22 ± 2%, p = 0.009) but not in chronic phase (1157 ± 57 ms vs. 1120 ± 54 ms, p = 0.934; 23 ± 2% vs. 20 ± 1%, p = 0.109). From acute to chronic MI, infarcted native T1 peaked in subacute phase (1275 ± 63 ms vs. 1637 ± 123 ms vs. 1471 ± 98 ms, p < 0.001), while ECV progressively increased with time (35 ± 7% vs. 46 ± 6% vs. 52 ± 4%, p < 0.001). Native T1 correlated well with histological findings (R² = 0.65 to 0.89, all p < 0.001) so did ECV (R² = 0.73 to 0.94, all p < 0.001).

Conclusion

T1 mapping allows the quantitative assessment of injury in MI and the noninvasive monitoring of tissue injury evolution, which correlates well with histological findings.

Dynamic Changes in Microvascular Flow Conductivity and Perfusion After Myocardial Infarction Shown by Image-Based Modeling

Background

Microcirculation is a decisive factor in tissue reperfusion inadequacy following myocardial infarction (MI). Nonetheless, experimental assessment of blood flow in microcirculation remains a bottleneck. We sought to model blood flow properties in coronary microcirculation at different time points after MI and to compare them with healthy conditions to obtain insights into alterations in cardiac tissue perfusion.

Methods and Results

We developed an image‐based modeling framework that permitted feeding a continuum flow model with anatomical data previously obtained from the pig coronary microvasculature to calculate physiologically meaningful permeability tensors. The tensors encompassed the microvascular conductivity and were also used to estimate the arteriole–venule drop in pressure and myocardial blood flow. Our results indicate that the tensors increased in a bimodal pattern at infarcted areas on days 1 and 7 after MI while a nonphysiological decrease in arteriole–venule drop in pressure was observed; contrary, the tensors and the arteriole–venule drop in pressure on day 3 after MI, and in remote areas, were closer to values for healthy tissue. Myocardial blood flow calculated using the condition‐dependent arteriole–venule drop in pressure decreased in infarcted areas. Last, we simulated specific modes of vascular remodeling, such as vasodilation, vasoconstriction, or pruning, and quantified their distinct impact on microvascular conductivity.

Conclusions

Our study unravels time‐ and region‐dependent alterations of tissue perfusion related to the structural changes occurring in the coronary microvasculature due to MI. It also paves the way for conducting simulations in new therapeutic interventions in MI and for image‐based microvascular modeling by applying continuum flow models in other biomedical scenarios.

[68Ga]-NODAGA-RGD Positron Emission Tomography (PET) for Assessment of Post Myocardial Infarction Angiogenesis as a Predictor for Left Ventricular Remodeling in Mice after Cardiac Stem Cell Therapy

Angiogenesis plays a central role in the healing process following acute myocardial infarction. The PET tracer [⁶⁸Ga]-NODAGA-RGD, which is a ligand for the α_vβ₃ integrin, has been investigated for imaging angiogenesis in the process of healing myocardium in both animal and clinical studies. It’s value as a prognostic marker of functional outcome remains unclear. Therefore, the aim of this work was to establish [⁶⁸Ga]-NODAGA-RGD for imaging angiogenesis in the murine infarct model and evaluate the tracer as a predictor for cardiac remodeling in the context of cardiac stem cell therapy. [⁶⁸Ga]-NODAGA-RGD PET performed seven days after left anterior descending coronary artery (LAD) occlusion in 129S6 mice showed intense tracer accumulation within the infarct region. The specificity was shown in a sub-group of animals by application of the competitive inhibitor cilengitide prior to tracer injection in a subgroup of animals. Myocardial infarction (MI) significantly reduced cardiac function and resulted in pronounced left ventricular remodeling after three weeks, as measured by cardiac MRI in a separate group. Cardiac induced cells (CiC) that were derived from mESC injected intramyocardially in the therapy group significantly improved left ventricular ejection fraction (LVEF). Surprisingly, CiC transplantation resulted in significantly lower tracer accumulation seven days after MI induction. Accordingly, we successfully established the PET tracer [⁶⁸Ga]-NODAGA-RGD for the assessment of α_vβ₃ integrin expression in the healing process after MI in the mouse model. Yet, our results indicate that the mere extent of angiogenesis following MI does not serve as a sufficient prognostic marker for functional outcome.

Morroniside enhances angiogenesis and improves cardiac function following acute myocardial infarction in rats

Angiogenesis is critical for re-establishing blood supply to the ischemic myocardium after acute myocardial infarction (AMI). This study aimed to investigate the effects of morroniside on angiogenesis after AMI and explored associated proangiogenic mechanisms. A rat model of AMI was established by ligation of the left anterior descending coronary artery followed by administration of three doses of morroniside. Immunofluorescence staining was performed to identify newly generated endothelial cells and arterioles. The protein expression levels associated with angiogenesis were examined by western blots. Echocardiography was used to examine cardiac function. Our data revealed that morroniside promoted angiogenesis and improved cardiac function in rats with AMI. The proangiogenic effect of morroniside might be mediated by the VEGFA/VEGF receptor 2 signaling pathway.

Myocardial Extracellular Volume Fraction Allows Differentiation of Reversible Versus Irreversible Myocardial Damage and Prediction of Adverse Left Ventricular Remodeling of ST-Elevation Myocardial Infarction

BACKGROUND

The relationship between dynamic changes of myocardial injury in ST-elevation myocardial infarction (STEMI) patients and long-term prognosis is still unclear.

PURPOSE

To evaluate the extracellular volume fraction (ECV) in the differentiation of reversible from irreversible myocardial injury and the prediction value of left ventricular adverse remodeling in patients with STEMI after reperfusion.

STUDY TYPE

Prospective.

POPULATION

Twenty-four STEMI patients after reperfusion were included FIELD STRENGTH/SEQUENCE: 3.0 T, T₁ mapping, ECV, T₂ -STIR, and late gadolinium enhancement (LGE).

ASSESSMENT

All the patients underwent cardiac MRI at four timepoints (days 1, 3, and 7, and at 6 months). The regions of interest (ROIs) were selected at the infarcted myocardium (with/without intramyocardial hemorrhage [IMH] and microvascular obstruction [MVO]).

STATISTICAL TESTS

One-way analysis of variance and the Kruskal-Wallis test were used for the statistical analysis.

RESULTS

Native T₁ of MI (without MVO/IMH) gradually decreased after reperfusion (P < 0.05). The ECV of MI increased during the first 3 days and then slowly declined. Native T₁ of MI with MVO/IMH was the lowest (1184 msec; 1108.5-1266), while ECV (78%; 65.5-87%) was the highest, P < 0.001. Native T₁ and ECV of salvageable myocardium were higher than those of the remote myocardium but lower than those of the MI without MVO or IMH (P < 0.001). ROC analysis revealed an area under the curve (AUC) of ECV (0.85, P < 0.001) for differentiating infarcted and salvageable myocardium was higher than that of native T₁ mapping (AUC: 0.63, P < 0.001) in the first week after STEMI (P < 0.0001). T₁ and ECV differed significantly between patients with and without left ventricle adverse remodeling (P < 0.05).

DATA CONCLUSION

Dynamic temporal changes in reversibly and irreversibly damaged myocardia were differentiated via native T₁ and ECV mapping after primary percutaneous coronary intervention in STEMI patients. ECV may better reflect microvascular injury severity and myocardial viability. MI with higher native T₁ and ECV or with severe microvascular injury (MVO and IMH) was correlated with adverse LV remodeling.

LEVEL OF EVIDENCE

2 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2020. J. Magn. Reson. Imaging 2020;52:476-487.

Astragaloside IV alleviates heart failure by promoting angiogenesis through the JAK-STAT3 pathway

CONTEXT

Heart failure (HF) is one of the most serious diseases worldwide. Astragaloside IV (ASI) is widely used for the treatment of cardiovascular disease in China.

OBJECTIVE

To evaluate the protective effect of ASI on the HF in a Sprague-Dawley rat model of left coronary artery ligation, and investigate the angiogenesis-related mechanisms.

MATERIALS AND METHODS

Left coronary artery was ligated to induce a rat model of HF, and the rats were treated with vehicle (saline) or different doses of ASI (0.1, 0.3 and 1 mg/kg/day) by oral gavage for 6 weeks. Cardiac function was evaluated by echocardiography. Infarct size was determined by triphenyltetrazolium chloride staining. Cardiac vascular density was analyzed by microangiography. Real-time PCR, Western blot and chromatin immunoprecipitation were performed to investigate the mechanisms.

RESULTS

ASI treatment improved the body weight and survival rate of HF rats, as well as the cardiac function of HF rats, with significantly improved ejection fraction (75.27 ± 5.75% vs. 36.26 ± 4.14%) and fractional shortening (45.39 ± 3.66% vs. 17.88 ± 1.32%). ASI reduced the infarct size of the HF rats by 47%. ASI promoted angiogenesis, with increased vascular density (2.08-fold) and induced mRNA expression of CD31 (1.81-fold) and VEGF (2.70-fold) in the ischemic heart. Furthermore, ASI induced the phosphorylation of JAK (1.89-fold) and STAT3 (2.95-fold), as well as the activity of VEGF promoter which was regulated by STAT3.

DISCUSSION AND CONCLUSIONS

ASI alleviated HF by promoting angiogenesis through JAK-STAT3 pathway, providing novel alternative strategies to prevent HF in the future.

Injectable human recombinant collagen matrices limit adverse remodeling and improve cardiac function after myocardial infarction

Despite the success of current therapies for acute myocardial infarction (MI), many patients still develop adverse cardiac remodeling and heart failure. With the growing prevalence of heart failure, a new therapy is needed that can prevent remodeling and support tissue repair. Herein, we report on injectable recombinant human collagen type I (rHCI) and type III (rHCIII) matrices for treating MI. Injecting rHCI or rHCIII matrices in mice during the late proliferative phase post-MI restores the myocardium's mechanical properties and reduces scar size, but only the rHCI matrix maintains remote wall thickness and prevents heart enlargement. rHCI treatment increases cardiomyocyte and capillary numbers in the border zone and the presence of pro-wound healing macrophages in the ischemic area, while reducing the overall recruitment of bone marrow monocytes. Our findings show functional recovery post-MI using rHCI by promoting a healing environment, cardiomyocyte survival, and less pathological remodeling of the myocardium.