Rat carotid artery balloon injury model

Intravascular delivery of an MK2 inhibitory peptide to prevent restenosis after angioplasty

Peripheral artery disease is commonly treated with balloon angioplasty, a procedure involving minimally invasive, transluminal insertion of a catheter to the site of stenosis, where a balloon is inflated to open the blockage, restoring blood flow. However, peripheral angioplasty has a high rate of restenosis, limiting long-term patency. Therefore, angioplasty is sometimes paired with delivery of cytotoxic drugs like paclitaxel to reduce neointimal tissue formation. We pursue intravascular drug delivery strategies that target the underlying cause of restenosis - intimal hyperplasia resulting from stress-induced vascular smooth muscle cell switching from the healthy contractile into a pathological synthetic phenotype. We have established MAPKAP kinase 2 (MK2) as a driver of this phenotype switch and seek to establish convective and contact transfer (coated balloon) methods for MK2 inhibitory peptide delivery to sites of angioplasty. Using a flow loop bioreactor, we showed MK2 inhibition in ex vivo arteries suppresses smooth muscle cell phenotype switching while preserving vessel contractility. A rat carotid artery balloon injury model demonstrated inhibition of intimal hyperplasia following MK2i coated balloon treatment in vivo. These studies establish both convective and drug coated balloon strategies as promising approaches for intravascular delivery of MK2 inhibitory formulations to improve efficacy of balloon angioplasty.

Vascular restenosis following paclitaxel-coated balloon therapy is attributable to NLRP3 activation and LIN9 upregulation

Lower limb arterial occlusive disease is treated with intraluminal devices, such as paclitaxel (PTX)-coated balloons (PCBs); however, post-procedural restenosis remains a significant challenge. NLRP3 activation is known to play a significant role in atherosclerosis, but its involvement in restenosis following PCB intervention remains to be investigated. We identified that NLRP3 was differentially expressed in lower-limb arterial tissues sourced from healthy controls and patients with arterial occlusive disease. Through cell experiments, we confirmed that PTX is involved in the activation of NLRP3. Subsequently, we demonstrated that NLRP3 activation promotes the proliferation and migration of vascular smooth muscle cell (VSMC), thereby reducing their sensitivity to PTX. NLRP3 activation also stimulates the secretion of the inflammatory cytokine interleukin IL-1β. RNA sequencing of IL-1β-treated VSMC revealed the upregulation of BRD4 and LIN9. Further mechanistic investigations confirmed that IL-1β facilitates BRD4 recruitment, leading to enhanced LIN9 expression. The transcription factor LIN9 binds to the promoter region of the cell-cycle regulator AURKA, thereby promoting its transcription and subsequently upregulating the expression of the cell proliferation-associated molecule FOXM1. These processes ultimately mediate the proliferation, migration, and PTX resistance of VSMC. Additionally, we discovered that JQ1 inhibited the overexpression of the above molecules, and exhibited a synergistic effect with PTX. Our conclusions were validated through in vivo experiments in Sprague-Dawley rats. Collectively, our findings provide insights into the molecular mechanisms underlying restenosis following PCB therapy, and suggest that the combined use of JQ1 and PTX devices may represent a promising therapeutic strategy.

Atlas of Cell Repertoire Within Neointimal Lesions Is Metabolically Altered in Hypertensive Rats

BACKGROUND

High blood pressure has been suggested to accelerate vascular injury-induced neointimal formation and progression. However, little is known about the intricate relationships between vascular injury and hypertension in the context of arterial remodeling.

METHODS

Single-cell RNA-sequencing analysis was used to depict the cell atlas of carotid arteries of Wistar Kyoto rats and spontaneously hypertensive rats with or without balloon injury.

RESULTS

We found that hypertension significantly aggravated balloon injury-induced arterial stenosis. A total of 36 202 cells from carotid arteries with or without balloon injury were included in single-cell RNA-sequencing analysis. Cell composition analysis showed that vascular injury and hypertension independently induced distinct aortic cell phenotypic alterations including immune cells, endothelial cells (ECs), and smooth muscle cells. Specifically, our data showed that injury and hypertension-induced specific EC phenotypic alterations, and revealed a transition from functional ECs to hypermetabolic, and eventually dysfunctional ECs in hypertensive rats upon balloon injury. Importantly, our data also showed that vascular injury and hypertension-induced different smooth muscle cell phenotypic alterations, characterized by deferential expression of synthetic signatures. Interestingly, pathway analysis showed that dysregulated metabolic pathways were a common feature in monocytes/macrophages, ECs, and smooth muscle cells in response to injury and hypertension. Functionally, we demonstrate that inhibition of mitochondrial respiration significantly ameliorated injury-induced neointimal formation in spontaneously hypertensive rats.

CONCLUSIONS

This study provides the cell landscape changes of the main aortic cell phenotypic alterations in response to injury and hypertension. Our findings suggest that targeting cellular mitochondrial respiration could be a novel therapeutic for patients with hypertension undergoing vascular angioplasty.

BAY-9835: Discovery of the First Orally Bioavailable ADAMTS7 Inhibitor

The matrix metalloprotease ADAMTS7 has been identified by multiple genome-wide association studies as being involved in the development of coronary artery disease. Subsequent research revealed the proteolytic function of the enzyme to be relevant for atherogenesis and restenosis after vessel injury. Based on a publicly known dual ADAMTS4/ADAMTS5 inhibitor, we have in silico designed an ADAMTS7 inhibitor of the catalytic domain, which served as a starting point for an optimization campaign. Initially our inhibitors suffered from low selectivity vs MMP12. An X-ray cocrystal structure inspired us to exploit amino acid differences in the binding site of MMP12 and ADAMTS7 to improve selectivity. Further optimization composed of employing 5-membered heteroaromatic groups as hydantoin substituents to become more potent on ADAMTS7. Finally, fine-tuning of DMPK properties yielded BAY-9835, the first orally bioavailable ADAMTS7 inhibitor. Further optimization to improve selectivity vs ADAMTS12 seems possible, and a respective starting point could be identified.

In Vivo Visualization and Quantification of Rat Laryngeal Blood Supply After Hydration Challenge

OBJECTIVES

Systemic dehydration decreases total body blood volume; however, hemodynamic alterations at the level of local organs, such as the larynx, remain unclear. Here we sought to quantify superior thyroid artery (STA) blood flow after dehydration and rehydration using in vivo magnetic resonance angiography (MRA) and ultrasound imaging in a rat model.

METHODS

Male Sprague-Dawley rats (N = 17) were included in this prospective, repeated measures design. Rats first underwent MRA to determine baseline STA cross-sectional area, followed by high-frequency in vivo ultrasound imaging to measure STA blood velocity at baseline. Next, rats were systemically dehydrated (water withholding), followed by rehydration (water ad-lib). Ultrasound imaging was repeated immediately after dehydration and following rehydration. The STA blood velocity and STA cross-sectional area were used to compute STA blood flow. Three rats served as temporal controls for ultrasound imaging. To determine if the challenges to hydration status affected the STA cross-sectional area, four rats underwent only MRA at baseline, dehydration, and rehydration.

RESULTS

Systemic dehydration resulted in 10.5% average body weight loss. Rehydration resulted in average body weight gain of 10.9%. Statistically significant reductions were observed in STA mean blood flow rate after dehydration. Rehydration reversed these changes to pre-dehydration levels. No significant differences were observed in STA cross-sectional area with dehydration or rehydration.

CONCLUSION

Systemic dehydration decreased blood flow in the superior thyroid artery. Rehydration restored blood flow in the STA. Change in hydration status did not alter the STA cross-sectional area. These preliminary findings demonstrate the feasibility of using ultrasound and MRA to quantify hemodynamic changes and visualize laryngeal blood vessels.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:779-785, 2024.

Myeloid-derived growth factor suppresses VSMC dedifferentiation and attenuates postinjury neointimal formation in rats by activating S1PR2 and its downstream signaling

Restenosis after angioplasty is caused usually by neointima formation characterized by aberrant vascular smooth muscle cell (VSMC) dedifferentiation. Myeloid-derived growth factor (MYDGF), secreted from bone marrow-derived monocytes and macrophages, has been found to have cardioprotective effects. In this study we investigated the effect of MYDGF to postinjury neointimal formation and the underlying mechanisms. Rat carotid arteries balloon-injured model was established. We found that plasma MYDGF content and the level of MYDGF in injured arteries were significantly decreased after balloon injury. Local application of exogenous MYDGF (50 μg/mL) around the injured vessel during balloon injury markedly ameliorated the development of neointimal formation evidenced by relieving the narrow endovascular diameter, improving hemodynamics, and reducing collagen deposition. In addition, local application of MYDGF inhibited VSMC dedifferentiation, which was proved by reversing the elevated levels of osteopontin (OPN) protein and decreased levels of α-smooth muscle actin (α-SMA) in the left carotid arteries. We showed that PDGF-BB (30 ng/mL) stimulated VSMC proliferation, migration and dedifferentiation in vitro; pretreatment with MYDGF (50-200 ng/mL) concentration-dependently eliminated PDGF-BB-induced cell proliferation, migration and dedifferentiation. Molecular docking revealed that MYDGF had the potential to bind with sphingosine-1-phosphate receptor 2 (S1PR2), which was confirmed by SPR assay and Co-IP analysis. Pretreatment with CCG-1423 (Rho signaling inhibitor), JTE-013 (S1PR2 antagonist) or Ripasudil (ROCK inhibitor) circumvented the inhibitory effects of MYDGF on VSMC phenotypic switching through inhibiting S1PR2 or its downstream RhoA-actin monomers (G-actin) /actin filaments (F-actin)-MRTF-A signaling. In summary, this study proves that MYDGF relieves neointimal formation of carotid arteries in response to balloon injury in rats, and suppresses VSMC dedifferentiation induced by PDGF-BB via S1PR2-RhoA-G/F-actin-MRTF-A signaling pathway. In addition, our results provide evidence for cross talk between bone marrow and vasculature.

Generation of a novel ex-vivo model to study re-endothelialization

Endothelial dysfunction initiates the pathogenesis of a myriad of cardiovascular diseases, yet the precise underlying mechanisms remain unclear. Current model utilises mechanical denudation of arteries resulting in an arterial-injury model with onset of intimal hyperplasia (IH). Our study shows that 5 min enzymatic denudation of human umbilical artery (hUA) lumen at 37 °C efficiently denudes hUA while maintaining vessel integrity without significantly increase intima-media thickness after 7 days in culture. This ex-vivo model will be a valuable tool in understanding the mechanism of re-endothelialization prior to smooth muscle cells (SMC) activation thus placating IH at an early stage.

FoxO3 normalizes Smad3-induced arterial smooth muscle cell growth

Transition of arterial smooth muscle (ASM) from a quiescent, contractile state to a growth-promoting state is a hallmark of cardiovascular disease (CVD), a leading cause of death and disability in the United States and worldwide. While many individual signals have been identified as important mechanisms in this phenotypic conversion, the combined impact of the transcription factors Smad3 and FoxO3 in ASM growth is not known. The purpose of this study was to determine that a coordinated, phosphorylation-specific relationship exists between Smad3 and FoxO3 in the control of ASM cell growth. Using a rat in vivo arterial injury model and rat primary ASM cell lysates and fractions, validated low and high serum in vitro models of respective quiescent and growth states, and adenoviral (Ad-) gene delivery for overexpression (OE) of individual and combined Smad3 and/or FoxO3, we hypothesized that FoxO3 can moderate Smad3-induced ASM cell growth. Key findings revealed unique cellular distribution of Smad3 and FoxO3 under growth conditions, with induction of both nuclear and cytosolic Smad3 yet primarily cytosolic FoxO3; Ad-Smad3 OE leading to cytosolic and nuclear expression of phosphorylated and total Smad3, with almost complete reversal of each with Ad-FoxO3 co-infection in quiescent and growth conditions; Ad-FoxO3 OE leading to enhanced cytosolic expression of phosphorylated and total FoxO3, both reduced with Ad-Smad3 co-infection in quiescent and growth conditions; Ad-FoxO3 inducing expression and activity of the ubiquitin ligase MuRF-1, which was reversed with concomitant Ad-Smad3 OE; and combined Smad3/FoxO3 OE reversing both the pro-growth impact of singular Smad3 and the cytostatic impact of singular FoxO3. A primary takeaway from these observations is the capacity of FoxO3 to reverse growth-promoting effects of Smad3 in ASM cells. Additional findings lend support for reciprocal antagonism of Smad3 on FoxO3-induced cytostasis, and these effects are dependent upon discrete phosphorylation states and cellular localization and involve MuRF-1 in the control of ASM cell growth. Lastly, results showing capacity of FoxO3 to normalize Smad3-induced ASM cell growth largely support our hypothesis, and overall findings provide evidence for utility of Smad3 and/or FoxO3 as potential therapeutic targets against abnormal ASM growth in the context of CVD.

Highly reproducible rat arterial injury model of neointimal hyperplasia

Models of arterial injury in rodents have been invaluable to our current understanding of vessel restenosis and play a continuing role in the development of endovascular interventions for cardiovascular disease. Mechanical distention of the vessel wall and denudation of the vessel endothelium are the two major modes of vessel injury observed in most clinical pathologies and are critical to the reproducible modelling of progressive neointimal hyperplasia. The current models which have dominated this research area are the mouse wire carotid or femoral injury and the rat carotid balloon injury. While these elicit simultaneous distension of the vessel wall and denudation of the luminal endothelium, each model carries limitations that need to be addressed using a complementary injury model. Wire injuries in mice are highly technical and procedurally challenging due to small vessel diameters, while rat balloon injuries require permanent blood vessel ligation and disruption of native blood flow. Complementary models of vascular injury with reproducibility, convenience, and increased physiological relevance to the pathophysiology of endovascular injury would allow for improved studies of neointimal hyperplasia in both basic and translational research. In this study, we developed a new surgical model that elicits vessel distention and endothelial denudation injury using sequential steps using microforceps and a standard needle catheter inserted via arteriotomy into a rat common carotid artery, without requiring permanent ligation of branching arteries. After 2 weeks post-injury this model elicits highly reproducible neointimal hyperplasia and rates of re-endothelialisation similar to current wire and balloon injury models. Furthermore, evaluation of the smooth muscle cell phenotype profile, inflammatory response and extracellular matrix within the developing neointima, showed that our model replicated the vessel remodelling outcomes critical to restenosis and those becoming increasingly focused upon in the development of new anti-restenosis therapies.

Transcriptomic and physiological analyses reveal temporal changes contributing to the delayed healing response to arterial injury in diabetic rats

Objective

Atherosclerosis is a leading cause of mortality in the rapidly growing population with diabetes mellitus. Vascular interventions in patients with diabetes can lead to complications attributed to defective vascular remodeling and impaired healing response in the vessel wall. In this study, we aim to elucidate the molecular differences in the vascular healing response over time using a rat model of arterial injury applied to healthy and diabetic conditions.

Methods

Wistar (healthy) and Goto-Kakizaki (GK, diabetic) rats (n = 40 per strain) were subjected to left common carotid artery (CCA) balloon injury and euthanized at different timepoints: 0 and 20 hours, 5 days, and 2, 4, and 6 weeks. Noninvasive morphological and physiological assessment of the CCA was performed with ultrasound biomicroscopy (Vevo 2100) and corroborated with histology. Total RNA was isolated from the injured CCA at each timepoint, and microarray profiling was performed (n = 3 rats per timepoint; RaGene-1_0-st-v1 platform). Bioinformatic analyses were conducted using R software, DAVID bioinformatic tool, online STRING database, and Cytoscape software.

Results

Significant increase in the neointimal thickness (P < .01; two-way analysis of variance) as well as exaggerated negative remodeling was observed after 2 weeks of injury in GK rats compared with heathy rats, which was confirmed by histological analyses. Bioinformatic analyses showed defective expression patterns for smooth muscle cells and immune cell markers, along with reduced expression of key extracellular matrix-related genes and increased expression of pro-thrombotic genes, indicating potential faults on cell regulation level. Transcription factor-protein-protein interaction analysis provided mechanistic evidence with an array of transcription factors dysregulated in diabetic rats.

Conclusions

In this study, we have demonstrated that diabetic rats exhibit impaired arterial remodeling characterized by a delayed healing response. We show that increased contractile smooth muscle cell marker expression coincided with decreased matrix metalloproteinase expression, indicating a potential mechanism for a lack of extracellular matrix reorganization in the impaired vascular healing in GK rats. These results further corroborate the higher prevalence of restenosis in patients with diabetes and provide vital molecular insights into the mechanisms contributing to the impaired arterial healing response in diabetes. Moreover, the presented study provides the research community with the valuable longitudinal gene expression data bank for further exploration of diabetic vasculopathy.

Methyltransferase like 3-mediated N6-methylatidin methylation inhibits vascular smooth muscle cells phenotype switching via promoting phosphatidylinositol 3-kinase mRNA decay

N6-methylatidine (m6A) is involved in post-transcriptional metabolism and a variety of pathological processes. However, little is known about the role of m6A in vascular proliferative diseases, particularly in vascular smooth muscle cells (VSMCs) phenotype switching-induced neointimal hyperplasia. In the current study, we discovered that methyltransferase like 3 (METTL3) is a critical candidate for catalyzing a global increase in m6A in response to carotid artery injury and various VSMCs phenotype switching. The inhibited neointimal hyperplasia was obtained after in vivo gene transfer to knock-down Mettl3. In vitro overexpression of Mettl3 resulted in increased VSMC proliferation, migration, and reduced contractile gene expression with a global elevation of m6A modification. In contrast, Mettl3 knockdown reversed this facilitated phenotypic switch in VSMCs, as demonstrated by downregulated m6A, decreased proliferation, migration, and increased expression of contractile genes. Mechanistically, Mettl3 knock-down was found to promote higher phosphatidylinositol 3-kinase (Pi3k) mRNA decay thus inactivating the PI3K/AKT signal to inhibit VSMCs phenotype switching. Overall, our findings highlight the importance of METTL3-mediated m6A in VSMCs phenotype switching and offer a novel perspective on targeting METTL3 as a therapeutic option for VSMCs phenotype switching modulated pathogenesis, including atherosclerosis and restenosis.

Systemic single administration of anti-inflammatory microRNA 146a-5p loaded in polymeric nanomedicines with active targetability attenuates neointimal hyperplasia by controlling inflammation in injured arteries in a rat model

Neointimal hyperplasia (NIH) after revascularization is a key unsolved clinical problem. Various studies have shown that attenuation of the acute inflammatory response on the vascular wall can prevent NIH. MicroRNA146a-5p (miR146a-5p) has been reported to show anti-inflammatory effects by inhibiting the NF-κB pathway, a well-known key player of inflammation of the vascular wall. Here, a nanomedicine, which can reach the vascular injury site, based on polymeric micelles was applied to deliver miR146a-5p in a rat carotid artery balloon injury model. In vitro studies using inflammation-induced vascular smooth muscle cell (VSMC) was performed. Results showed anti-inflammatory response as an inhibitor of the NF-κB pathway and VSMC migration, suppression of reactive oxygen species production, and proinflammatory cytokine gene expression in VSMCs. A single systemic administration of miR146a-5p attenuated NIH and vessel remodeling in a carotid artery balloon injury model in both male and female rats in vivo. MiR146a-5p reduced proinflammatory cytokine gene expression in injured arteries and monocyte/macrophage infiltration into the vascular wall. Therefore, miR146a-5p delivery to the injury site demonstrated therapeutic potential against NIH after revascularization.

Icariside II Restores Vascular Smooth Muscle Cell Contractile Phenotype by Enhancing the Focal Adhesion Signaling Pathway in the Rat Vascular Remodeling Model

Vascular smooth muscle cell (VSMC) phenotypic transition represents the fundamental pathophysiological alteration in the vascular remodeling process during the initiation and progression of cardiovascular diseases. Recent studies have revealed that Icariside II (ICS-II), a flavonol glycoside derived from the traditional Chinese medicine Herba Epimedii, exhibited therapeutic effects in various cardiovascular diseases. However, the therapeutic efficacy and underlying mechanisms of ICS-II regarding VSMC phenotypic transition were unknown. In this study, we investigated the therapeutic effects of ICS-Ⅱ on vascular remodeling with a rat’s balloon injury model in vivo. The label-free proteomic analysis was further implemented to identify the differentially expressed proteins (DEPs) after ICS-II intervention. Gene ontology and the pathway enrichment analysis were performed based on DEPs. Moreover, platelet-derived growth factor (PDGF-BB)-induced primary rat VSMC was implemented to verify the restoration effects of ICS-II on the VSMC contractile phenotype. Results showed that ICS-II could effectively attenuate the vascular remodeling process, promote SMA-α protein expression, and inhibit OPN expression in vivo. The proteomic analysis identified 145 differentially expressed proteins after ICS-II intervention. Further, the bioinformatics analysis indicated that the focal adhesion signaling pathway was enriched in the ICS-II group. In vitro studies showed that ICS-II suppressed VSMC proliferation and migration, and promoted VSMC contractile phenotype by modulating the focal adhesion signaling pathway. Taken together, our results suggest that ICS-II attenuates the vascular remodeling process and restores the VSMC contractile phenotype by promoting the focal adhesion pathway.

Downregulation of the endothelial histone demethylase JMJD3 is associated with neointimal hyperplasia of arteriovenous fistulas in kidney failure

Jumonji domain-containing protein-3 (JMJD3), a histone H3 lysine 27 (H3K27) demethylase, promotes endothelial regeneration, but its function in neointimal hyperplasia (NIH) of arteriovenous fistulas (AVFs) has not been explored. In this study, we examined the contribution of endothelial JMJD3 to NIH of AVFs and the mechanisms underlying JMJD3 expression during kidney failure. We found that endothelial JMJD3 expression was negatively associated with NIH of AVFs in patients with kidney failure. JMJD3 expression in endothelial cells (ECs) was also downregulated in the vasculature of chronic kidney disease (CKD) mice. In addition, specific knockout of endothelial JMJD3 delayed EC regeneration, enhanced endothelial mesenchymal transition, impaired endothelial barrier function as determined by increased Evans blue staining and inflammatory cell infiltration, and accelerated neointima formation in AVFs created by venous end to arterial side anastomosis in CKD mice. Mechanistically, JMJD3 expression was downregulated via binding of transforming growth factor beta 1-mediated Hes family transcription factor Hes1 to its gene promoter. Knockdown of JMJD3 enhanced H3K27 methylation, thereby inhibiting transcriptional activity at promoters of EC markers and reducing migration and proliferation of ECs. Furthermore, knockdown of endothelial JMJD3 decreased endothelial nitric oxide synthase expression and nitric oxide production, leading to the proliferation of vascular smooth muscle cells. In conclusion, we demonstrate that decreased expression of endothelial JMJD3 impairs EC regeneration and function and accelerates neointima formation in AVFs. We propose increasing the expression of endothelial JMJD3 could represent a new strategy for preventing endothelial dysfunction, attenuating NIH, and improving AVF patency in patients with kidney disease.

Simultaneous Noninvasive Detection and Therapy of Atherosclerosis Using HDL Coated Gold Nanorods

Cardiovascular disease (CVD) is a major cause of death and disability worldwide. A real need exists in the development of new, improved therapeutic methods for treating CVD, while major advances in nanotechnology have opened new avenues in this field. In this paper, we report the use of gold nanoparticles (GNPs) coated with high-density lipoprotein (HDL) (GNP-HDL) for the simultaneous detection and therapy of unstable plaques. Based on the well-known HDL cardiovascular protection, by promoting the reverse cholesterol transport (RCT), injured rat carotids, as a model for unstable plaques, were injected with the GNP-HDL. Noninvasive detection of the plaques 24 h post the GNP injection was enabled using the diffusion reflection (DR) method, indicating that the GNP-HDL particles had accumulated in the injured site. Pathology and noninvasive CT measurements proved the recovery of the injured artery treated with the GNP-HDL. The DR of the GNP-HDL presented a simple and highly sensitive method at a low cost, resulting in simultaneous specific unstable plaque diagnosis and recovery.

Galangin inhibits neointima formation induced by vascular injury via regulating the PI3K/AKT/mTOR pathway

Galangin inhibits neointimal hyperplasia after vascular injury by inhibiting vascular smooth muscle cell proliferation, migration, phenotypic switching and promoting autophagy.

Single-Cell RNA Sequencing of the Rat Carotid Arteries Uncovers Potential Cellular Targets of Neointimal Hyperplasia

Aims: In-stent restenosis (ISR) remains an Achilles heel of drug-eluting stents despite technical advances in devices and procedural techniques. Neointimal hyperplasia (NIH) is the most important pathophysiological process of ISR. The present study mapped normal arteries and stenotic arteries to uncover potential cellular targets of neointimal hyperplasia.

Methods and Results: By comparing the left (control) and right (balloon injury) carotid arteries of rats, we mapped 11 clusters in normal arteries and 11 mutual clusters in both the control and experimental groups. Different clusters were categorized into 6 cell types, including vascular smooth muscle cells (VSMCs), fibroblasts, endothelial cells (ECs), macrophages, unknown cells and others. An abnormal cell type expressing both VSMC and fibroblast markers at the same time was termed a transitional cell via pseudotime analysis. Due to the high proportion of VSMCs, we divided them into 6 clusters and analyzed their relationship with VSMC phenotype switching. Moreover, N-myristoyltransferase 1 (NMT1) was verified as a credible VSMC synthetic phenotype marker. Finally, we proposed several novel target genes by disease susceptibility gene analysis, such as Cyp7a1 and Cdk4, which should be validated in future studies.

Conclusion: Maps of the heterogeneous cellular landscape in the carotid artery were defined by single-cell RNA sequencing and revealed several cell types with their internal relations in the ISR model. This study highlights the crucial role of VSMC phenotype switching in the progression of neointimal hyperplasia and provides clues regarding the underlying mechanism of NIH.

RhoGDI1-Cdc42 Signaling Is Required for PDGF-BB-Induced Phenotypic Transformation of Vascular Smooth Muscle Cells and Neointima Formation

RhoGTPase is involved in PDGF-BB-mediated VSMC phenotypic modulation. RhoGDIs are key factors in regulating RhoGTPase activation. In the present study, we investigated the regulatory effect of RhoGDI1 on the activation of RhoGTPase in VSMC transformation and neointima formation. Western blot and co-immunoprecipitation assays showed that the PDGF receptor inhibition by crenolanib promoted RhoGDI1 polyubiquitination and degradation. Inhibition of RhoGDI1 degradation via MG132 reversed the decrease in VSMC phenotypic transformation. In addition, RhoGDI1 knockdown significantly inhibited VSMC phenotypic transformation and neointima formation in vitro and in vivo. These results suggest that PDGF-BB promotes RhoGDI1 stability via the PDGF receptor and induces the VSMC synthetic phenotype. The co-immunoprecipitation assay showed that PDGF-BB enhanced the interaction of RhoGDI1 with Cdc42 and promoted the activation of Cdc42; these enhancements were blocked by crenolanib and RhoGDI1 knockdown. Moreover, RhoGDI1 knockdown and crenolanib pretreatment prevented the localization of Cdc42 to the plasma membrane (PM) to activate and improve the accumulation of Cdc42 on endoplasmic reticulum (ER). Furthermore, Cdc42 inhibition or suppression significantly reduced VSMC phenotypic transformation and neointima formation in vitro and in vivo. This study revealed the novel mechanism by which RhoGDI1 stability promotes the RhoGDI1-Cdc42 interaction and Cdc42 activation, thereby affecting VSMC phenotypic transformation and neointima formation.

Cytokine-induced apoptosis inhibitor 1 (CIAPIN1) accelerates vascular remodelling via p53 and JAK2-STAT3 regulation in vascular smooth muscle cells

BACKGROUND AND PURPOSE

Abnormal vascular smooth muscle cell (VSMC) proliferation and migration lead to neointima formation, which eventually results in cardiovascular hyperplastic diseases. The molecular mechanisms underlying these cellular processes have not been fully understood. Cytokine-induced apoptosis inhibitor 1 (CIAPIN1) has been identified as an anti-apoptotic molecule, but little is known about its target genes and related pathways in VSMC dysfunction or its clinical implication in neointima formation following vascular injury.

EXPERIMENTAL APPROACH

Determination, using loss/gain-of-function approaches by gene delivery, of whether CIAPIN1 modulates VSMC proliferation, migration and neointima formation and the underlying mechanisms was carried out. Balloon injury or ligation and local delivery of lentivirus were performed on rat or mouse carotid arteries. Rat aortic smooth muscle cells, the primary cell, was used as the model to evaluate the effect of CIAPIN1 on proliferation and migration.

KEY RESULTS

CIAPIN1 was overexpressed in the neointimal region of rat arteries. CIAPIN1 deficiency markedly inhibited injury-induced or ligation-induced intimal hyperplasia and suppressed PDGF-BB-induced VSMC proliferation, migration and cell cycle progression, while overexpression promoted proliferation, migration and neointima formation. CIAPIN1 negatively regulated Tp53 transcription, which promoted cell cycle progression and migration via cyclin E1-CDK2/pRb/PCNA and the MMP2 pathway. CIAPIN1 also increased JAK2 expression, enhancing JAK2 and STAT3 phosphorylation by vascular injury, which forced phenotypic switching from contractile to synthetic state in injured arteries.

CONCLUSIONS AND IMPLICATIONS

These findings provide new insights into the mechanism by which CIAPIN1 regulates vascular remodelling and suggest a novel therapeutic target for treating vascular proliferative diseases.

Janus Kinase 3 Deficiency Promotes Vascular Reendothelialization-Brief Report

[Figure: see text].

Plasma Small Extracellular Vesicle-Carried miRNA-501-5p Promotes Vascular Smooth Muscle Cell Phenotypic Modulation-Mediated In-Stent Restenosis

Vascular smooth muscle cell (VSMC) phenotypic modulation plays an important role in the occurrence and development of in-stent restenosis (ISR), the underlying mechanism of which remains a key issue needing to be urgently addressed. This study is designed to investigate the role of plasma small extracellular vesicles (sEV) in VSMC phenotypic modulation. sEV were isolated from the plasma of patients with ISR (ISR-sEV) or not (Ctl-sEV) 1 year after coronary stent implantation using differential ultracentrifugation. Plasma sEV in ISR patients are elevated markedly and decrease the expression of VSMC contractile markers α-SMA and calponin and increase VSMC proliferation. miRNA sequencing and qRT-PCR validation identified that miRNA-501-5p was the highest expressed miRNA in the plasma ISR-sEV compared with Ctl-sEV. Then, we found that sEV-carried miRNA-501-5p level was significantly higher in ISR patients, and the level of plasma sEV-carried miRNA-501-5p linearly correlated with the degree of restenosis (R² = 0.62). Moreover, miRNA-501-5p inhibition significantly increased the expression of VSMC contractile markers α-SMA and calponin and suppressed VSMC proliferation and migration; in vivo inhibition of miRNA-501-5p could also blunt carotid artery balloon injury induced VSMC phenotypic modulation in rats. Mechanically, miRNA-501-5p promoted plasma sEV-induced VSMC proliferation by targeting Smad3. Notably, endothelial cells might be the major origins of miRNA-501-5p. Collectively, these findings showed that plasma sEV-carried miRNA-501-5p promotes VSMC phenotypic modulation-mediated ISR through targeting Smad3.

Exosomal Transfer of miR-185 Is Controlled by hnRNPA2B1 and Impairs Re-endothelialization After Vascular Injury

Dysfunction of endothelial cells (ECs) contributes to restenosis after vascular reconstruction for patients with coronary artery disease (CAD). The intercellular communication between ECs and vascular smooth muscle cells (VSMCs) might be critical in the development of restenosis and can be mediated by exosomes carrying functional microRNAs. miR-185 is reported to be associated with atherosclerosis, whether it plays a similar role in restenosis is unknown. In this study, we observed an elevated level of extracellular miR-185 in platelet-derived growth factor (PDGF)-stimulated VSMCs. The medium from PDGF-stimulated VSMCs promoted miR-185 expression in rat aortic ECs and inhibited EC angiogenesis. PDGF-stimulated VSMCs transferred miR-185 into ECs via exosomes. Furthermore, we found that the CXCL12 gene, a target of miR-185, is essential for the angiogenic potential of ECs. Exosomes derived from miR-185 mimic transfected VSMCs attenuated re-endothelialization after vascular injury. Moreover, we show that exosome-mediated miR-185 transfer is modulated by hnRNPA2B1. We also observed that hnRNPA2B1 is up-regulated during neointima formation and hnRNPA2B1 inhibition accelerates re-endothelialization and attenuates neointima formation following carotid injury. Taken together, our results indicate that exosomal miR-185 transfer from VSMCs to ECs is controlled by hnRNPA2B1 and impairs re-endothelialization after vascular injury.

Potential Target miR-455 Delaying Arterial Stenosis Progression Through PTEN

Background: Vascular smooth muscle cells (VSMC) underwent phenotypic switching upon stimulation signals, and this is the prerequisite for their proliferation and migration. Previous work revealed that miR-455 may be involved in vascular stenosis. Thus, this study aimed to explore potential targets and mechanisms underlying the dynamics of miR-455 in vascular stenosis.

Methods: miR-455 and PTEN expression levels were studied in normal and stenosis tissue, as well as in VSMC in proliferation model. Manipulating miR-455 expression levels was achieved by transfection of either miR-455 mimic or inhibitor, and its effect on cell proliferation was studied by CCK-8 assay. Its effect on gene expression was studied by RT-qPCR and western blot. The expression regulation mechanism was studied by luciferase reporter system. Finally, the effect of miR-455 on regulating vascular stenosis was studied using a rat balloon-injured carotid artery stenosis model.

Results: High expression levels of miR-455 were detected in both stenosis arterial tissues and VSMC proliferation models. In contrast, the expression levels of PTEN were downregulated in these systems. miR-455 transfected VSMC showed higher levels of proliferation and decreased levels of PTEN. Potential binding sites between miR-455 and PTEN 3′UTR were predicted and confirmed. NF-kB p65 was found to bind directly on miR-455 promoter region and regulate its transcription. The progression of arterial stenosis could be delayed by introducing miR-455 antagomir.

Conclusions: The p65/miR-455/PTEN signaling pathway plays a crucial role in regulating VSMC proliferation and vascular stenosis. This indicated that miR-455 is a novel target that would help improve treatment outcomes in patients suffering from vascular stenosis.

Light sheet fluorescence microscopy as a new method for unbiased three-dimensional analysis of vascular injury

AIMS

Assessment of preclinical models of vascular disease is paramount in the successful translation of novel treatments. The results of these models have traditionally relied on two-dimensional (2D) histological methodologies. Light sheet fluorescence microscopy (LSFM) is an imaging platform that allows for three-dimensional (3D) visualization of whole organs and tissues. In this study, we describe an improved methodological approach utilizing LSFM for imaging of preclinical vascular injury models while minimizing analysis bias.

METHODS AND RESULTS

The rat carotid artery segmental pressure-controlled balloon injury and mouse carotid artery ligation injury were performed. Arteries were harvested and processed for LSFM imaging and 3D analysis, as well as for 2D area histological analysis. Artery processing for LSFM imaging did not induce vessel shrinkage or expansion and was reversible by rehydrating the artery, allowing for subsequent sectioning and histological staining a posteriori. By generating a volumetric visualization along the length of the arteries, LSFM imaging provided different analysis modalities including volumetric, area, and radial parameters. Thus, LSFM-imaged arteries provided more precise measurements compared to classic histological analysis. Furthermore, LSFM provided additional information as compared to 2D analysis in demonstrating remodelling of the arterial media in regions of hyperplasia and periadventitial neovascularization around the ligated mouse artery.

CONCLUSION

LSFM provides a novel and robust 3D imaging platform for visualizing and quantifying arterial injury in preclinical models. When compared with classic histology, LSFM outperformed traditional methods in precision and quantitative capabilities. LSFM allows for more comprehensive quantitation as compared to traditional histological methodologies, while minimizing user bias associated with area analysis of alternating, 2D histological artery cross-sections.

Inhibition of ERK or Akt ameliorates intimal hyperplasia via up-regulation of Cx37 and down-regulation of Cx43 in balloon injury rat model

Background

Connexins (Cxs) are reported to participate in atherosclerosis associated intimal hyperplasia (IH), while their function involved in the balloon injury (BI) induced IH and restenosis is less reported.

Methods

Forty-eight male Sprague-Dawley rats were randomly assigned to not injured (NI) group and BI group, which were further administrated with ERK-inhibitor U0216 and Akt-inhibitor MIK2206. Western blot and RT-PCR were utilized to detect the expression of Cx30, Cx37, Cx40, and Cx43 at 6 hours, 24 hours, 7 days, and 14 days post-surgery. H&E staining and related intima area, media area, and luminal area measurement were applied to indicate neointima formation and IH. ERK and Akt phosphorylation levels and proliferating cell nuclear antigen (PCNA) immunostaining were also detected.

Results

Among the four Cxs detected, Cx37 showed down-regulated, and Cx43 showed up-regulated temporal expression pattern in BI rats with confirmed neointima formation. Up-regulated p-ERK (P<0.01) and p-Akt (P<0.01) can be detected in BI rats compared with NI rats. Meanwhile, U0216 and MIK2206 can significantly reduce Cx43 expression and increase CX37 expression accompanied with reduced neointima formation and PCNA staining (P<0.05 or P<0.01) in BI rats.

Conclusions

ERK or Akt inhibition can alleviate BI-induced IH via up-regulation of Cx37 and down-regulation of Cx43.

A Rat Carotid Artery Pressure-Controlled Segmental Balloon Injury with Periadventitial Therapeutic Application

Cardiovascular disease remains the leading cause of death and disability worldwide, in part due to atherosclerosis. Atherosclerotic plaque narrows the luminal surface area in arteries thereby reducing adequate blood flow to organs and distal tissues. Clinically, revascularization procedures such as balloon angioplasty with or without stent placement aim to restore blood flow. Although these procedures reestablish blood flow by reducing plaque burden, they damage the vessel wall, which initiates the arterial healing response. The prolonged healing response causes arterial restenosis, or re-narrowing, ultimately limiting the long-term success of these revascularization procedures. Therefore, preclinical animal models are integral for analyzing the pathophysiological mechanisms driving restenosis, and provide the opportunity to test novel therapeutic strategies. Murine models are cheaper and easier to operate on than large animal models. Balloon or wire injury are the two commonly accepted injury modalities used in murine models. Balloon injury models in particular mimic the clinical angioplasty procedure and cause adequate damage to the artery for the development of restenosis. Herein we describe the surgical details for performing and histologically analyzing the modified, pressure-controlled rat carotid artery balloon injury model. Additionally, this protocol highlights how local periadventitial application of therapeutics can be used to inhibit neointimal hyperplasia. Lastly, we present light sheet fluorescence microscopy as a novel approach for imaging and visualizing the arterial injury in three-dimensions.

Circular RNAs in the pathogenesis of atherosclerosis

Atherosclerosis is a common cause of cardiovascular and cerebrovascular diseases. Noncoding RNAs (ncRNAs), including microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs) have attracted substantial attention for their roles in various physiological and pathological processes. In recent years, research on the roles of circRNAs in atherosclerosis has progressed rapidly, and they have been implicated in the pathophysiological processes underlying the development of atherosclerosis, including changes in the functions of endothelial cells (ECs), vascular smooth muscle cells (VSMCs), and macrophages. In this review article, we summarize currently available data regarding the role of circRNAs in atherosclerosis and how circRNAs influence the development of atherosclerosis by regulating ECs, VSMCs, and macrophages. We also discuss their potential as diagnostic biomarkers for coronary artery disease.

ASK1 inhibition: a therapeutic strategy with multi-system benefits

p38 mitogen-activated protein kinases (P38α and β) and c-Jun N-terminal kinases (JNK1, 2, and 3) are key mediators of the cellular stress response. However, prolonged P38 and JNK signalling is associated with damaging inflammatory responses, reactive oxygen species-induced cell death, and fibrosis in multiple tissues, such as the kidney, liver, central nervous system, and cardiopulmonary systems. These responses are associated with many human diseases, including arthritis, dementia, and multiple organ dysfunctions. Attempts to prevent P38- and JNK-mediated disease using small molecule inhibitors of P38 or JNK have generally been unsuccessful. However, apoptosis signal-regulating kinase 1 (ASK1), an upstream regulator of P38 and JNK, has emerged as an alternative drug target for limiting P38- and JNK-mediated disease. Within this review, we compile the evidence that ASK1 mediates damaging cellular responses via prolonged P38 or JNK activation. We discuss the potential benefits of ASK1 inhibition as a therapeutic and summarise the studies that have tested the effects of ASK1 inhibition in cell and animal disease models, in addition to human clinical trials for a variety of disorders.

Transcriptomic profiling of experimental arterial injury reveals new mechanisms and temporal dynamics in vascular healing response

Objective

Endovascular interventions cause arterial injury and induce a healing response to restore vessel wall homeostasis. Complications of defective or excessive healing are common and result in increased morbidity and repeated interventions. Experimental models of intimal hyperplasia are vital for understanding the vascular healing mechanisms and resolving the clinical problems of restenosis, vein graft stenosis, and dialysis access failure. Our aim was to systematically investigate the transcriptional, histologic, and systemic reaction to vascular injury during a prolonged time.

Methods

Balloon injury of the left common carotid artery was performed in male rats. Animals (n = 69) were euthanized before or after injury, either directly or after 2 hours, 20 hours, 2 days, 5 days, 2 weeks, 6 weeks, and 12 weeks. Both injured and contralateral arteries were subjected to microarray profiling, followed by bioinformatic exploration, histologic characterization of the biopsy specimens, and plasma lipid analyses.

Results

Immune activation and coagulation were key mechanisms in the early response, followed by cytokine release, tissue remodeling, and smooth muscle cell modulation several days after injury, with reacquisition of contractile features in later phases. Novel pathways related to clonal expansion, inflammatory transformation, and chondro-osteogenic differentiation were identified and immunolocalized to neointimal smooth muscle cells. Analysis of uninjured arteries revealed a systemic component of the reaction after local injury, underlined by altered endothelial signaling, changes in overall tissue bioenergy metabolism, and plasma high-density lipoprotein levels.

Conclusions

We demonstrate that vascular injury induces dynamic transcriptional landscape and metabolic changes identifiable as early, intermediate, and late response phases, reaching homeostasis after several weeks. This study provides a temporal “roadmap” of vascular healing as a publicly available resource for the research community.

Endovascular intervention causes an injury to the arterial wall that subsequently induces a healing response to restore the vessel wall homeostasis. Complications after vascular interventions related to defective or excessive healing response, such as thrombosis or restenosis, are common and result in increased morbidity, suffering of the patient, need for repeated interventions, and possibly death. Thus, there is a need for better understanding of the underlying molecular mechanisms during vascular injury and healing response to identify and to assess the risk of complications in patients. Using an experimental model of vascular injury, this study demonstrates the full landscape of dynamic transcriptional changes in the resolution of vascular injury, accompanied also by systemic variations in plasma lipid levels and reaching homeostasis several weeks after injury. These results can guide the development of new strategies and molecular targets for modulation of the intimal response on endovascular interventions.

MicroRNA-126 protects against vascular injury by promoting homing and maintaining stemness of late outgrowth endothelial progenitor cells

BACKGROUND

Endothelial progenitor cells (EPCs) contribute to reendothelialization and neovascularization and protect against vascular injury and ischemia of various organs. We have previously shown downregulation of microRNA (miR)-126 in EPCs from diabetic patients, which contributes to dysfunction of EPCs including impaired migratory ability. The aims of the present study were to examine (1) in vitro the effects of miR-126 on the homing and stemness of late outgrowth EPCs (LOCs), along with relevant signaling pathways, and (2) in vivo the effects of modulating LOCs by manipulating miR-126 expression on LOC homing and reendothelialization of injured arteries in GK rats (a non-obese diabetes model).

METHODS

Rat bone marrow-derived LOCs were transfected with miR-126 inhibitor or lentiviral vectors expressing miR-126. LOC migration was determined by transwell migration assay. CXCR4 expression was measured by real-time PCR, Western blotting, and confocal microscopy while related signaling pathway proteins were measured by Western Blotting. Stemness gene expression, and gene and protein expression and promoter activity of KLF-8 were also measured. LOCs transfected with lenti-miR-126 or miR-126 inhibitor were injected into GK rats with carotid artery injury, and then vascular reendothelialization and the extent of intimal hyperplasia were examined.

RESULTS

Lenti-miR-126 increased while miR-126 inhibitor decreased LOC migration and CXCR4 expression on LOCs. miR-126 positively regulated p-ERK, VEGF, p-Akt, and eNOS protein expression, and inhibitors of these proteins blocked miR-126-induced CXCR4 expression and also reduced LOC migration. Overexpression of miR-126 promoted while inhibition of miR-126 suppressed stemness gene expression in LOCs. miR-126 also inhibited gene and protein expression and promoter activity of KLF-8 while shRNA-mediated knockdown of KLF-8 increased stemness gene expression. Upregulation of stemness gene expression by miR-126 overexpression was completely abrogated by co-transfection of lenti-KLF-8 and lenti-miR-126 into LOCs. In GK rats, transplantation of LOCs overexpressing miR-126 enhanced LOC homing and reendothelialization and decreased intimal hyperplasia of injured arteries.

CONCLUSION

Our results indicate that miR-126 protects against vascular injury by promoting CXCR4 expression and LOC homing via ERK/VEGF and Akt/eNOS signaling pathways and maintaining stemness via targeting KLF-8.

Oral Resolvin D1 attenuates early inflammation but not intimal hyperplasia in a rat carotid angioplasty model

Inflammation ensuing from vascular injury promotes intimal hyperplasia (IH) and restenosis. Resolvin D1 (RvD1) is a lipid mediator that attenuates IH in vivo when delivered locally to the vessel wall in animal models. We tested the hypothesis that peri-procedural oral administration of RvD1 could blunt the local inflammatory response to angioplasty, and attenuate downstream IH. Carotid angioplasty was performed on rats fed with either RvD1 or vehicle through oral gavage, starting one day prior to injury until post-operative day (POD) 3 or 14 when arteries were harvested. To study pharmacokinetics and bioactivity of oral RvD1, we measured plasma RvD1 by ELISA, whole blood phagocytosis activity using flow cytometry, and cAMP levels in the thoracic aorta by ELISA. Carotid arteries were harvested on POD3 for staining (anti-CD45, anti-Myeloperoxidase (MPO), anti-Ki67 or dihydroethidium (DHE) for reactive oxygen species), mRNA expression of target genes (quantitative RT-PCR), or on POD14 for morphometry (elastin stain). RvD1 plasma concentration peaked 3 h after gavage in rats, at which point we concurrently observed an increase in circulating monocyte phagocytosis activity and aortic cAMP levels in RvD1-treated rats vs. vehicle. Oral RvD1 attenuated local arterial inflammation after angioplasty by reducing CD45+, MPO+, Ki67+ cells, and DHE staining intensity. Oral RvD1 also reduced the expression of several pro-inflammatory genes within the injured vessels. However, oral RvD1 did not significantly reduce IH. Oral RvD1 attenuated acute inflammation within the arterial wall after angioplasty in rats, but did not significantly affect IH.

Down-regulation of Suv39h1 attenuates neointima formation after carotid artery injury in diabetic rats

Patients with diabetes have an increased risk of vascular complications. Suv39h1, a histone methyltransferase, plays a protective role against myocardial injury in diabetes. Herein, we intend to explore whether Suv39h1 could affect neointimal formation after vascular injury in diabetic rats and reveal the underlying mechanism. In this study, we generated adenovirus expressing Suv39h1 as well as lentivirus expressing Suv39h1‐targeting shRNA and evaluated the significance of Suv39h1 in vascular smooth muscle cells (VSMCs) under diabetic conditions. In vitro, we examined proliferative and migratory behaviours as well as the underlying signalling mechanisms in VSMCs in response to high glucose treatment. In vivo, we induced diabetes in SD rats with streptozocin and established the common carotid artery balloon injury model. Suv39h1 was found to be both necessary and sufficient to promote VSMC proliferation and migration under high glucose conditions. We observed corresponding changes in intracellular signalling molecules including complement C3 and phosphor‐ERK1/2. However, either up‐regulating or down‐regulating Suv39h1, phosphor‐p38 level was not significantly affected. Consistently, Suv39h1 overexpression led to accelerated neointima formation, while knocking down Suv39h1 reduced it following carotid artery injury in diabetic rats. Using microarray analyses, we showed that altering the Suv39h1 level in vivo dramatically altered the expression of myriad genes mediating different biological processes and molecular function. This study reveals the novel role of Suv39h1 in VSMCs of diabetes and suggests its potential role as a therapeutic target in diabetic vascular injury.

Suppression of circDcbld1 Alleviates Intimal Hyperplasia in Rat Carotid Artery by Targeting miR-145-3p/Neuropilin-1

We replicated the rat common carotid artery (CCA) intima hyperplasia model and found the expression of a circular RNA, circRNA_009723 (circDcbld1), was markedly increased in the CCA with intimal hyperplasia. In vitro, the suppression of circDcbld1 in rat vascular smooth muscle cells (VSMCs) led the increase of contractile smooth muscle cell markers and the decrease of cell migration. In vivo, the injection of chemically modified circDcbld1 small interfering RNA (siRNA) lessened the formation of neointima in rat CCA after balloon injury. Further experiments proved that circDcbld1, as a competing endogenous RNA, interacted with miR-145-3p and upregulated the level of neuropilin-1 (Nrp1), thereby regulating the migration of VSMCs. In this study, we demonstrated a new mechanism by which circular RNA promotes intimal hyperplasia. We deem that intervention in the circDcbld1-miR-145-3p/Nrp1 pathway might be a feasible approach to alleviate the post-injury intimal hyperplasia.

Expression profile of circular RNA in rat intimal hyperplasia and target gene prediction

Intimal hyperplasia is an important cause of stenosis or occlusion after vascular injury. Circular RNAs (circRNAs) are known to be related to various cardiovascular diseases. However, the expression profile of circRNAs in the neointima has not been reported in detail. In this study, we established a rat common carotid artery (CCA) injury model. A microarray detection showed significant differences in circRNA expression between the normal and injured CCA. Real-time quantitative polymerase chain reaction verified the differences. We used bioinformatics to predict the microRNAs that possibly interact with the differentially expressed (DE) circRNAs and linked the potential functions of circRNAs to the target genes of the microRNAs. We believe that the DE circRNA in neointima may affect the differentiation, proliferation, and migration of vascular cells through a variety of target genes. The intervention or utilization of certain circRNAs should be a new method for preventing and treating intimal hyperplasia.

Noninvasive in vivo Assessment of the Re-endothelialization Process Using Ultrasound Biomicroscopy in the Rat Carotid Artery Balloon Injury Model

OBJECTIVES

Ultrasound biomicroscopy (UBM), or ultra high-frequency ultrasound, is a technique used to assess the anatomy of small research animals. In this study, UBM was used to assess differences in intimal hyperplasia thickness as a surrogate measurement of the re-endothelialization process after carotid artery balloon injury in rats.

METHODS

Ultrasound biomicroscopic data from 3 different experiments and rat strains (Sprague Dawley, Wistar, and diabetic Goto-Kakizaki) were analyzed. All animals were subjected to carotid artery balloon injury and examined with UBM (30-70 MHz) 2 and 4 weeks after injury. Re-endothelialization on UBM was defined as the length from the carotid bifurcation to the most distal visible edge of the intimal hyperplasia. En face staining with Evans blue dye was performed at euthanasia 4 weeks after injury, followed by tissue harvesting for histochemical and immunohistochemical evaluations.

RESULTS

A significant correlation (Spearman r = 0.63; P < .0001) was identified when comparing all measurements of re-endothelialization obtained from UBM and en face staining. The findings revealed a similar pattern for all rat strains: Sprague Dawley (Spearman r = 0.70; P < .0001), Wistar (Spearman r = 0.36; P < .081), and Goto-Kakizaki (Spearman r = 0.70; P < .05). A Bland-Altman test showed agreement between en face staining and UBM. Immunohistochemical staining confirmed the presence of the endothelium in the areas detected as re-endothelialized by the UBM assessment.

CONCLUSIONS

Ultrasound biomicroscopy can be used for repeated in vivo assessment of re-endothelialization after carotid artery balloon injury in rats.

Long noncoding RNA H19 promotes vascular remodeling by sponging let-7a to upregulate the expression of cyclin D1

Vascular remodeling is mainly caused by excessive proliferation of vascular smooth muscle cells (VSMCs). Noncoding RNAs (ncRNAs) have emerged as important regulators in diverse pathological processes. Previous work has shown the functions and mechanisms of long noncoding RNA H19 (LncRNA H19) on VSMCs. As long noncoding RNAs (lncRNAs) are complex in their mechanisms of action, the aim of the study is to identify if there are any other molecular mechanisms of LncRNA H19 on VSMCs. In vivo studies demonstrated that cyclin D1 was overexpressed in neointima of balloon-injured artery. In vitro studies identified that the overexpression of LncRNA H19 promoted VSMCs proliferation and cyclin D1 upregulation. On the contrary, cellular proliferation and expression of cyclin D1 were inhibited in VSMCs after infection with let-7a. Furthermore, luciferase reporter assays and RNA pull-down assays were used to explore the regulatory mechanism, we found that LncRNA H19 functioned as a competing endogenous RNA (ceRNA) by sponging let-7a to promote the expression of the target gene cyclin D1. In conclusion, LncRNA H19 positively regulated cyclin D1 expression through directly binding to let-7a in VSMCs. Our findings provide new insight into the mechanism of LncRNA H19 in VSMCs proliferation and vascular remodeling, and further indicate the implications of LncRNA H19 in the diagnosis and treatment of vascular proliferative diseases.

Exosomes from mesenchymal stem cells expressing miR-125b inhibit neointimal hyperplasia via myosin IE

Intercellular communication between mesenchymal stem cells (MSCs) and their target cells in the perivascular environment is modulated by exosomes derived from MSCs. However, the potential role of exosome-mediated microRNA transfer in neointimal hyperplasia remains to be investigated. To evaluate the effects of MSC-derived exosomes (MSC-Exo) on neointimal hyperplasia, their effects upon vascular smooth muscle cell (VSMC) growth in vitro and neointimal hyperplasia in vivo were assessed in a model of balloon-induced vascular injury. Our results showed that MSC-Exo were internalised by VSMCs and inhibited proliferation and migration in vitro. Further analysis revealed that miR-125b was enriched in MSC-Exo, and repressed the expression of myosin 1E (Myo1e) by targeting its 3' untranslated region. Additionally, MSC-Exo and exosomally transferred miR-125b repressed Myo1e expression and suppressed VSMC proliferation and migration and neointimal hyperplasia in vivo. In summary, our findings revealed that MSC-Exo can transfer miR-125b to VSMCs and inhibit VSMC proliferation and migration in vitro and neointimal hyperplasia in vivo by repressing Myo1e, indicating that miR-125b may be a therapeutic target in the treatment of vascular diseases.

Smooth muscle cell-driven vascular diseases and molecular mechanisms of VSMC plasticity

Vascular smooth muscle cells (VSMCs) are the major cell type in blood vessels. Unlike many other mature cell types in the adult body, VSMC do not terminally differentiate but retain a remarkable plasticity. Fully differentiated medial VSMCs of mature vessels maintain quiescence and express a range of genes and proteins important for contraction/dilation, which allows them to control systemic and local pressure through the regulation of vascular tone. In response to vascular injury or alterations in local environmental cues, differentiated/contractile VSMCs are capable of switching to a dedifferentiated phenotype characterized by increased proliferation, migration and extracellular matrix synthesis in concert with decreased expression of contractile markers. Imbalanced VSMC plasticity results in maladaptive phenotype alterations that ultimately lead to progression of a variety of VSMC-driven vascular diseases. The nature, extent and consequences of dysregulated VSMC phenotype alterations are diverse, reflecting the numerous environmental cues (e.g. biochemical factors, extracellular matrix components, physical) that prompt VSMC phenotype switching. In spite of decades of efforts to understand cues and processes that normally control VSMC differentiation and their disruption in VSMC-driven disease states, the crucial molecular mechanisms and signalling pathways that shape the VSMC phenotype programme have still not yet been precisely elucidated. In this article we introduce the physiological functions of vascular smooth muscle/VSMCs, outline VSMC-driven cardiovascular diseases and the concept of VSMC phenotype switching, and review molecular mechanisms that play crucial roles in the regulation of VSMC phenotypic plasticity.

Murine models of vascular endothelial injury: Techniques and pathophysiology

Vascular endothelial injury (VEI) triggers pathological processes in various cardiovascular diseases, such as coronary heart disease and hypertension. To further elucidate the in vivo pathological mechanisms of VEI, many animal models have been established. For the easiness of genetic manipulation and feeding, murine models become most commonly applied for investigating VEI. Subsequently, countless valuable information concerning pathogenesis has been obtained and therapeutic strategies for VEI have been developed. This review will highlight some typical murine VEI models from the perspectives of pharmacological intervention, surgery and genetic manipulation. The techniques, pathophysiology, advantages, disadvantages and the experimental purpose of each model will also be discussed.

Mathematical model of hypertension-induced arterial remodeling: A chemo-mechanical approach

The development of chronic hypertension is a poorly described process involving many chemical and structural changes to the artery. Typically, mathematical models of this disease focus primarily on the mechanical aspects such as arterial geometry, elasticity, and tissue content, or alternatively on the chemical drivers of vasoactivity such as nitric oxide and reactive oxygen species. This paper presents a model that considers the powerful interaction between mechanical and biochemical drivers of hypertension and arterial remodeling. Based on biological processes thought to be involved in the development of hypertension, we have built a system of algebraic, differential, and integral equations. Endothelial dysfunction, which is known to limit vasodilation, is explicitly considered in the model and plays a vital role in the development of chronic hypertension. Numerical solutions to the system are consistent with available experimental data for normal and spontaneously-hypertensive rats.

RhoA/ROCK signaling regulates smooth muscle phenotypic modulation and vascular remodeling via the JNK pathway and vimentin cytoskeleton

The RhoA/ROCK signaling pathway regulates cell morphology, adhesion, proliferation, and migration. In this study, we investigated the regulatory role of RhoA/ROCK signaling on PDGF-BB-mediated smooth muscle phenotypic modulation and vascular remodeling and clarified the molecular mechanisms behind these effects. PDGF-BB treatment induced the activation of RhoA, ROCK, PDGF-Rβ, and the expression of PDGF-Rβ in HA-VSMCs (human aortic vascular smooth muscle cells). PDGF-Rβ inhibition and RhoA suppression blocked PDGF-BB-induced RhoA activation and ROCK induction. In addition, PDGF-BB-mediated cell proliferation and migration were suppressed by PDGF-Rβ inhibition, RhoA suppression, and ROCK inhibition, suggesting that PDGF-BB promotes phenotypic modulation of HA-VSMCs by activating the RhoA/ROCK pathway via the PDGF receptor. Moreover, suppressing both ROCK1 and ROCK2 blocked cell cycle progression from G0/G1 to S phase by decreasing the transcription and protein expression of cyclin D1, CDK2, and CDK4 via JNK/c-Jun pathway, thus reducing cell proliferation in PDGF-BB-treated HA-VSMCs. ROCK1 deletion, rather than ROCK2 suppression, significantly inhibited PDGF-BB-induced migration by reducing the expression of vimentin and preventing the remodeling of vimentin and phospho-vimentin. Furthermore, ROCK1 deletion suppressed vimentin by inhibiting the phosphorylation of Smad2/3 and the nuclear translocation of Smad4. These findings suggested that ROCK1 and ROCK2 might play different roles in PDGF-BB-mediated cell proliferation and migration in HA-VSMCs. In addition, PDGF-BB and its receptor participated in neointima formation and vascular remodeling by promoting cell cycle protein expression via the JNK pathway and enhancing vimentin expression in a rat balloon injury model; effects that were inhibited by treatment with fasudil. Together, the results of this study reveal a novel mechanism through which RhoA/ROCK signaling regulates smooth muscle phenotypic modulation and vascular remodeling via the JNK pathway and vimentin cytoskeleton.

Assessment of HIF-1α expression and release following endothelial injury in-vitro and in-vivo

Background

Endothelial injury is an early and enduring feature of cardiovascular disease. Inflammation and hypoxia may be responsible for this, and are often associated with the up-regulation of several transcriptional factors that include Hypoxia Inducible Factor-1 (HIF-1). Although it has been reported that HIF-1α is detectable in plasma, it is known to be unstable. Our aim was to optimize an assay for HIF-1α to be applied to in vitro and in vivo applications, and to use this assay to assess the release kinetics of HIF-1α following endothelial injury.

Methods

An ELISA for the measurement of HIF-1α in cell-culture medium and plasma was optimized, and the assay was used to determine the best conditions for sample collection and storage. The results of the ELISA were validated using Western blotting and immunohistochemistry (IHC). In vitro, a standardized injury was produced in a monolayer of rat aortic endothelial cells (RAECs) and intracellular HIF-1α was measured at intervals over 24 h. In vivo, a rat angioplasty model was used. The right carotid artery was injured using a 2F Fogarty balloon catheter. HIF-1α was measured in the plasma and in the arterial tissue (0, 1, 2, 3 and 5 days post injury).

Results

The HIF-1α ELISA had a limit of detection of 2.7 pg/mL and was linear up to 1000 pg/ mL. Between and within-assay, the coefficient of variation values were less than 15%. HIF-1α was unstable in cell lysates and plasma, and it was necessary to add a protease inhibitor immediately after collection, and to store samples at -80 °C prior to analysis. The dynamics of HIF-1α release were different for the in vitro and in vivo models. In vitro, HIF-1α reached maximum concentrations approximately 2 h post injury, whereas peak values in plasma and tissues occurred approximately 2 days post injury, in the balloon injury model.

Conclusion

HIF-1α can be measured in plasma, but this requires careful sample collection and storage. The carotid artery balloon injury model is associated with the transient release of HIF-1α into the circulation that probably reflects the hypoxia induced in the artery wall.

Electronic supplementary material

The online version of this article (10.1186/s10020-018-0026-5) contains supplementary material, which is available to authorized users.

PET Study of Sphingosine-1-Phosphate Receptor 1 Expression in Response to Vascular Inflammation in a Rat Model of Carotid Injury

Sphingosine-1-phosphate receptor (S1PR) activation plays a key role in vascular inflammatory response. Here, we report in vivo validation of [¹¹C]TZ3321, a potent S1PR1 radioligand, for imaging vascular inflammation in a rat model of carotid injury. The right common carotid artery of male adult Sprague-Dawley rats was injured by balloon overinflation that denuded the endothelium and distended the vessel wall. Animals received a 60-minute micro-positron emission tomography (micro PET) scan with [¹¹C]TZ3321 at 72 hours after injury. Ex vivo autoradiography was also conducted. The expression and cellular location of S1PR1 were examined by immunohistological analysis. Three-dimensional (3D) reconstruction of the first 100-second microPET/computed tomography (CT) image indicated the location of bilateral common carotid arteries. [¹¹C]TZ3321 displayed significantly higher accumulation (standardized uptake values: 0.93 ± 0.07 vs 0.78 ± 0.09, n = 6, P = .001) in the injured carotid artery than in the contralateral side. Increased tracer uptake in the injured artery was confirmed by autoradiography (photostimulated luminescence measures: 85.5 ± 0.93 vs 71.48 ± 6.22, n = 2). Concordantly, high S1PR1expression was observed in infiltrated inflammatory cells in the injured artery. Our studies demonstrate [¹¹C]TZ3321 microPET is able to detect the acute upregulation of S1PR1 expression in inflamed carotid artery. Therefore, [¹¹C]TZ3321 has potential to be a PET radiotracer for detecting early inflammatory response and monitoring therapeutic efficacy of vascular inflammation.

Photodynamic therapy of balloon-injured rat carotid arteries using indocyanine green

Photodynamic therapy (PDT) has been used to inhibit intimal hyperplasia in injured arteries. Because of the limited tissue penetration of visible light, an endovascular light source with a guided wire is often required for effective treatment. Indocyanine green (ICG), a near-infrared (NIR) photosensitizer, has been used in PDT for cancers. An extracorporeal light source may be used for shallow tissue because of the better tissue penetration of NIR light. The aim of this study was to evaluate the effect of ICG-PDT using extracorporeal NIR light on the inhibition of intimal hyperplasia in balloon-injured carotid arteries. A balloon injury (BI) model was used to induce intimal hyperplasia of carotid artery. Sprague-Dawley rats were divided into control, BI, BI + 1 × PDT, and BI + 2 × PDT groups. The control group underwent a sham procedure. PDT was performed 7 days after BI. In the BI + 1 × PDT group, ICG was administered 1 h before light irradiation. External illumination with 780-nm light-emitting diode light at a fluence of 4 J/cm² was applied. For the BI + 2 × PDT group, PDT was performed again at day 7, following the first PDT. Hematoxylin and eosin (H & E) staining was performed to assess vessel morphology. Arterial wall thickness was significantly larger in the BI group compared with the control group. ICG-PDT significantly reduced arterial wall thickness compared with the BI group. Repeated PDT further decreased arterial wall thickness to the level of the control group. These findings indicate a promising approach for the treatment of restenosis of carotid arteries.

A New Technique to Induce Experimental Myointimal Hyperplasia

BACKGROUND

Arterial myointimal hyperplasia (MIH) has a significant impact on the long-term outcomes of vascular procedures such as bypass surgery and angioplasty. In this study, we describe a new and innovative technique to induce MIH using a dental flossing cachet in Wistar rats.

METHODS

The intimal damage in the common carotid artery was induced by inserting the tip of the dental flossing cachet through the external carotid artery into the common carotid artery and turning it on for 3 rounds of 20 s each (n = 10). After 2 weeks, the rats were anesthetized and the common carotid arteries of the experimental side and the contralateral side (control) were harvested and preserved for histopathological studies.

RESULTS

The experimental carotid arteries showed significant intimal proliferation and thickening compared to the controls. The intima/media ratio of the experimental and normal (control) common carotid arteries were 1.274 ± 0.162 and 0.089 ± 0.023 (mean ± SEM), respectively (p < 0.001).

CONCLUSION

This technique is simple, inexpensive, and highly reproducible and it induces sufficient MIH to study this phenomenon in animal models.

The Rabbit Model of Accelerated Atherosclerosis: A Methodological Perspective of the Iliac Artery Balloon Injury

Acute coronary syndrome resulting from coronary occlusion following atherosclerotic plaque development and rupture is the leading cause of death in the industrialized world. New Zealand White (NZW) rabbits are widely used as an animal model for the study of atherosclerosis. They develop spontaneous lesions when fed with atherogenic diet; however, this requires long time of 4 - 8 months. To further enhance and accelerate atherogenesis, a combination of atherogenic diet and mechanical endothelial injury is often employed. The presented procedure for inducing atherosclerotic plaques in rabbits uses a balloon catheter to disrupt the endothelium in the left iliac artery of NZW rabbits fed with atherogenic diet. Such mechanical damage caused by the balloon catheter induces a chain of inflammatory reactions initiating neointimal lipid accumulation in a time dependent fashion. Atherosclerotic plaque following balloon injury show neointimal thickening with extensive lipid infiltration, high smooth muscle cell content and presence of macrophage derived foam cells. This technique is simple, reproducible and produces plaque of controlled length within the iliac artery. The whole procedure is completed within 20 - 30 min. The procedure is safe with low mortality and also offers high success in obtaining substantial intimal lesions. The procedure of balloon catheter induced arterial injury results in atherosclerosis within two weeks. This model can be used for investigating the disease pathology, diagnostic imaging and to evaluate new therapeutic strategies.