Acute Vascular Injury Research Articles

Abstract 109: The Chromatin Remodeling Protein Brg1 Regulates Adventitial Progenitor Cell Myofibroblast Differentiation And Pathological Vascular Remodeling

Cardiovascular diseases lead to long-term stiffening of arteries and small vessels. The vascular wall contains several cellular populations that coordinate to maintain vessel homeostasis and induce vascular remodeling in disease states. We identified a population of smooth muscle-derived progenitor cells that reside in the adventitial layer (AdvSca1-SM cells) that drive vascular fibrosis after acute vascular injury. AdvSca1-SM cells can differentiate into myofibroblasts and secrete numerous pro-remodeling factors including extracellular matrix proteins and pro-inflammatory cytokines. While the response of AdvSca1-SM cells to vascular injury has been studied, the epigenetic changes that influence their differentiation towards myofibroblasts is poorly understood. We observed Brahma-related gene 1 (Brg1), a highly conserved chromatin remodeling ATPase, is upregulated in AdvSca1-SM cells in response to vascular injury and may be a key factor in regulating gene expression to influence AdvSca1-SM differentiation. We hypothesize that Brg1 induces expression of gene sets associated with remodeling and fibrosis and ultimately drives AdvSca1-SM cell differentiation towards pathologic myofibroblasts. Results: Carotid arteries from mice subject to carotid ligation exhibit decreased perivascular collagen deposition, smaller neointima, decreased adventitial expansion, decreased numbers of alpha-actin positive AdvSca1-SM cells, and fewer infiltrating macrophages when treated with the pharmacological Brg1 bromodomain inhibitor PFI-3 as compared to mice that received vehicle control. In a cell culture system, TGF-β induces AdvSca1-SM cells to express myofibroblast-specific genes, including alpha actin and periostin, and demonstrate enhanced contractile function in collagen contraction assays. PFI-3 blocks TGF-β induced myofibroblast gene expression and dampens contractile function. Gene Ontology analysis reveals the top 100 TGF-β inducible genes blunted by PFI-3 are related to fibrosis and extracellular matrix signaling. In conclusion, these results suggest Brg1 is a major regulator of vascular remodeling and fibrosis and may be a targetable protein to help people who suffer from disease-related vascular stiffening.

Abstract 240: Role Of Smooth Muscle-derived Vascular Progenitor Cells In Atherosclerosis

Purpose: Atherosclerosis is a major cause of morbidity and mortality worldwide, but current therapies fail to adequately meet clinical needs. Emerging evidence implicates the outer layer of the blood vessel, the adventitia, in the pathogenesis of atherosclerosis. Specifically, it has been suggested that expansion of adventitial microvessels, the vasa vasorum (VV), drives atherosclerosis progression by facilitating inflammatory cell infiltration. Our group previously identified a unique population of multipotent resident vascular stem cells (AdvSca1-SM cells) that derive from mature vascular smooth muscle cells (SMCs) and reside in the vessel adventitia, where they are poised to respond to vascular injury. We hypothesized that in the setting of atherosclerosis, AdvSca1-SM cells contribute to VV expansion to drive disease progression. Methods: We generated a highly specific lineage tracing mouse model in order to track AdvSca1-SM cells in vivo even if they differentiate into other cell types. Lineage tracing mice were placed on either normal chow or Western diet for 8 or 16 weeks, then vascular tissue was analyzed using IF microscopy, scRNA-Seq, and flow cytometry. Results: scRNA-Seq and flow cytometry revealed that AdvSca1-SM cells in atherosclerosis primarily differentiate into mature SMCs, modulated SMCs, and myofibroblasts. Contrary to our preliminary data, AdvSca1-SM cells very rarely differentiate into endothelial cells. Additionally, despite previous evidence of SMCs gaining a macrophage-like phenotype in atherosclerosis, we identified only rare instances of AdvSca1-SM cells contributing to macrophage populations. Conclusions: As in our findings in acute vascular injury, AdvSca1-SM cells in atherosclerosis predominantly differentiate into SMCs and myofibroblasts. Future studies on advanced lesions will define the functional role of AdvSca1-SM cells in atherosclerotic plaque progression.

Abstract 208: The Chromatin Remodeling Protein Brg1 Regulates Adventitial Progenitor Cell Myofibroblast Differentiation And Pathological Vascular Remodeling

Cardiovascular diseases lead to long-term stiffening of arteries and small vessels. The vascular wall contains several cellular populations that coordinate to maintain vessel homeostasis and induce vascular remodeling in disease states. We identified a population of smooth muscle-derived progenitor cells that reside in the adventitial layer (AdvSca1-SM cells) that drive vascular fibrosis after acute vascular injury. AdvSca1-SM cells can differentiate into myofibroblasts and secrete numerous pro-remodeling factors including extracellular matrix proteins and pro-inflammatory cytokines. While the response of AdvSca1-SM cells to vascular injury has been studied, the epigenetic changes that influence their differentiation towards myofibroblasts is poorly understood. We observed Brahma-related gene 1 (Brg1), a highly conserved chromatin remodeling ATPase, is upregulated in AdvSca1-SM cells in response to vascular injury and may be a key factor in regulating gene expression to influence AdvSca1-SM differentiation. We hypothesize that Brg1 induces expression of gene sets associated with remodeling and fibrosis and ultimately drives AdvSca1-SM cell differentiation towards pathologic myofibroblasts. Results: Carotid arteries from mice subject to carotid ligation exhibit decreased perivascular collagen deposition, smaller neointima, decreased adventitial expansion, decreased numbers of alpha-actin positive AdvSca1-SM cells, and fewer infiltrating macrophages when treated with the pharmacological Brg1 bromodomain inhibitor PFI-3 as compared to mice that received vehicle control. In a cell culture system, TGF-β induces AdvSca1-SM cells to express myofibroblast-specific genes, including alpha actin and periostin, and demonstrate enhanced contractile function in collagen contraction assays. PFI-3 blocks TGF-β induced myofibroblast gene expression and dampens contractile function. Gene Ontology analysis reveals the top 100 TGF-β inducible genes blunted by PFI-3 are related to fibrosis and extracellular matrix signaling. In conclusion, these results suggest Brg1 is a major regulator of vascular remodeling and fibrosis and may be a targetable protein to help people who suffer from disease-related vascular stiffening.

Abstract 563: Age-related Differences In Vascular Remodeling Resulting From Acute Injury

Background: The vascular system, like other organ systems, ages, leading to differences in remodeling due to injury. The hallmark of acute vascular injury is the formation of intimal hyperplasia. Vascular procedures performed in the elderly, such as angioplasty, stent and other cardiovascular procedures/surgeries, result in higher rates of acute vascular injury compared to younger adults. We explored age-related differences in vascular remodeling due to acute injury using the unilateral carotid artery ligation (CAL) murine model. Methods: Four-month and twenty-two-month-old C57BL/6 male mice underwent ligation of the left common carotid artery immediately received either angiotensin II (1.4 mg/kg/day; Lig+Ang II) or vehicle (phosphate-buffered saline; Lig) via subcutaneous osmotic minipumps for 4 weeks. Results: Compared to young murine arteries, histopathology showed increased thinning and straightening of elastin in 22 mo. old arteries, as well as increasing collagen deposition in the media layer, resulting in thicker vessel walls.Old vessels were more susceptible to insults, as observed in the Lig group. In turn, the old vessel remodeled with neo-intimal formation, fragmentation of elastin and narrowing of the lumen, whilst there was no neo-intimal formation in the young arteries under the same injury.Even though Ang II increased remodeling in the young vessels with neo-intimal formation, Ang II exacerbated remodeling in the aged arteries with enough intimal hyperplasia that led to the occlusion of the lumen with a necrotic core, and the complete disintegration of the elastin. Molecular analysis showed differences between young and old arteries with and without perturbation. Conclusions: Together, these results indicate that vascular ageing can be detected in old arteries, but that there are age-dependent differences in vascular remodeling following acute injury revealed through pathological and molecular analysis. Thus, this study has provided an invaluable tool for understanding the mechanisms of neo-intimal formation in restenosis to elderly patients following angioplasty and vein grafts. It is also a means for pre-clinical pharmacological interventions.

Abstract 317: Resident Vascular Adventitial Progenitor Cells Of Smooth Muscle Cell-lineage Adopt Profibrotic Phenotype And Contribute To Cardiac Fibrosis

Activated cardiac myofibroblasts are the major contributors to ECM deposition in pathological cardiovascular fibrosis, which is the characteristic feature of cardiovascular diseases. However, due to potential heterogeneity of myofibroblasts, the origin of these cells remains controversial. Using highly specific smooth muscle cell lineage-tracing mouse models, we discovered the smooth muscle cell origin of a subpopulation of resident vascular adventitial progenitor cells, defined by the expression of the stem cell marker Sca1 (AdvSca1-SM cells), which rapidly proliferate and adopt a myofibroblast phenotype in response to acute vascular injury. Further, we identified a specific gene signature of active hedgehog/Wnt/β-catenin/ Klf4 signaling in AdvSca1-SM cells and validated a Gli1 -CreERT2-ROSA26-YFP (Gli1) reporter mouse model to be a faithful lineage tracing system for AdvSca1-SM cells. However, the function of AdvSca1-SM cells in cardiac fibrosis is unknown. Using immunofluorescent staining and label-free second harmonic generation (SHG) imaging, we observed the expansion and migration of AdvSca1-SM cells in close association with perivascular and interstitial cardiac fibrosis in pressure overload-induced cardiac fibrosis in Gli1 reporter mice. We performed single cell RNA sequencing (scRNA-seq) to examine the phenotype of AdvSca1-SM cells in Angiotensin II (AngII) model. Our data showed that, upon AngII challenge, AdvSca1-SM cells differentiate along a profibrotic trajectory, which is characterized by loss of expression of Klf4 , the lncRNA, Meg3 , and stemness genes and up-regulation of myofibroblast genes. Importantly, AngII-induced profibrotic transcriptomic changes of AdvSca1-SM cells were recapitulated in human ventricular tissues exhibiting a gene signature of cardiac hypertrophy, emphasizing the translational significance of this phenotypic transition. Connectivity map analysis of the scRNA-seq data identified statins as potential candidates for inhibition of the profibrotic transition of AdvSca1-SM cells. In agreement, simvastatin induced the expression of stemness genes and inhibited TGFβ-induced up-regulation of αSMA and down-regulation of Klf4 in cultured AdvSca1-SM cells.

17R/S-Benzo-RvD1, a synthetic resolvin D1 analogue, attenuates neointimal hyperplasia in a rat model of acute vascular injury.

Persistent inflammation following vascular injury drives neointimal hyperplasia (NIH). Specialized lipid mediators (SPM) mediate resolution which attenuates inflammation and downstream NIH. We investigated the effects of a synthetic analogue of resolvin D1 (RvD1) on vascular cells and in a model of rat carotid angioplasty. Human venous VSMC and endothelial cells (EC) were employed in migration, cell shape, toxicity, proliferation and p65 nuclear translocation assays. Murine RAW 264.7 cells were utilized to test the effect of pro-resolving compounds on phagocytic activity. A model of rat carotid angioplasty was used to evaluate the effects of 17R/S-benzo-RvD1 (benzo-RvD1) and 17R-RvD1 applied to the adventitia via 25% Pluronic gel. Immunostaining was utilized to examine Ki67 expression and leukocyte recruitment. Morphometric analysis was performed on arteries harvested 14 days after injury. Exposure to benzo-RvD1 attenuated PDGF- stimulated VSMC migration across a range of concentrations (0.1-100 nM), similar to that observed with 17R-RvD1. Pre-treatment with either Benzo-RvD1 or 17R-RvD1 (10, 100nM) attenuated PDGF-BB-induced VSMC cytoskeletal changes to nearly baseline dimensions. Benzo-RvD1 demonstrated modest anti-proliferative activity on VSMC and EC at various concentrations, without significant cytotoxicity. Benzo-RvD1 (10nM) inhibited p65 nuclear translocation in cytokine-stimulated EC by 21% (p<0.05), similar to 17R-RvD1. Consistent with pro-resolving activities of other SPM, both 17R-RvD1 and benzo-RvD1 increased the phagocytic activity of RAW 264.7 cells against S. Aureus and Zymosan particles. There were no significant differences in Ki-67 or CD45 staining observed on day 3 after angioplasty. Periadventitial treatment with benzo-RvD1 reduced carotid neointimal area at 14 days compared to control (0.08 mm2 v. 0.18 mm2; p<0.05), with similar efficacy to 17R-RvD1. 17R/S-benzo-RvD1 and 17R-RvD1 exhibit similar pro-resolving and anti-migratory activity in cell-based assays, and both compounds attenuated NIH following acute arterial injury in rats. Further studies of the mechanisms of resolution following vascular injury, and the translational potential of SPM analogues, are indicated.

Chemokine-Based Therapeutics for the Treatment of Inflammatory and Fibrotic Convergent Pathways in COVID-19.

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by the SARS-CoV-2 betacoronavirus and has taken over 761,426 American lives as of the date of publication and will likely result in long-term, if not permanent, tissue damage for countless patients. COVID-19 presents with diverse and multisystemic pathologic processes, including a hyperinflammatory response, acute respiratory distress syndrome (ARDS), vascular injury, microangiopathy, tissue fibrosis, angiogenesis, and widespread thrombosis across multiple organs, including the lungs, heart, kidney, liver, and brain. C-X-C chemokines contribute to these pathologies by attracting inflammatory mediators, the disruption of endothelial cell integrity and function, and the initiation and propagation of the cytokine storm. Among these, CXCL10 is recognized as a critical contributor to the hyperinflammatory state and poor prognosis in COVID-19. CXCL10 is also known to regulate growth factor-induced fibrosis, and recent evidence suggests the CXCL10-CXCR3 signaling system may be vital in targeting convergent pro-inflammatory and pro-fibrotic pathways. This review will explore the mechanistic role of CXCL10 and related chemokines in fibrotic complications associated with COVID-19 and the potential of CXCL10-targeted therapeutics for early intervention and long-term treatment of COVID-19-induced fibrosis.

Abstract 12355: An Engineered High-Affinity ACE2 Peptide Therapeutically Alleviates Lung Vascular Endothelial Injury and Mortality Induced by Distinct SARS-CoV-2 Variants

Introduction: Vaccine hesitancy and the continuous emergence of SARS-CoV-2 variants of concern that partially escape vaccine-induced immune responses highlight the urgent need for the development of effective therapeutics for COVID-19 patients. Hypothesis: The Engineered high-affinity ACE2 peptide has a therapeutic effect for SARS-CoV-2 and its variant-induced acute lung vascular injury. Methods: K18-hACE2 transgenic mice were inoculated with SARS-CoV-2 WA-1/2020 or P.1 variant of concerns to induce acute lung injury. The sACE2 2 .v2.4-IgG1 was injected once a day for consecutively 7 days starting from 12 hours at 10 mg/kg/day or 24 hours at 15 mg/kg/day post-SARS-CoV-2 inoculation. Results: We demonstrated that the higher binding affinity of sACE2 2 .v2.4-IgG1 to S proteins of the original SARS-CoV-2 WA-1/2020 isolate and the B.1.1.7 (Alpha, UK isolate), B.1.351 (Beta, South Africa isolate), P.1 (Gamma, Brazil isolate), and B.1.617.2 (Delta, India isolate) SARS-CoV-2 variants of concern compared to wild-type soluble ACE2. Using humanized K18-hACE2 mice, we found that both SARS-CoV-2 isolate WA-1/2020 and the P.1 variant of concern induced severe acute lung endothelial injury, which resulted in the severe transvascular leak, lung edema, and death. The P.1 variant induced severe lung vascular leak and death at an earlier time point at Day 5 compared to WA-1 at Day 7, consistent with increased viral entry and replication. Treatment with sACE2 2 .v2.4-IgG1 decoy peptide could be initiated as late as 24h after inoculation with a lethal dose of the SARS-CoV-2 WA-1/2020 isolate and profoundly reduces lung vascular injury and mortality. For the P.1 variant of concern, ACE2 2 .v2.4-IgG1 decoy peptide markedly improved survival and reduced lung vascular injury if administered early at 12 hours post-inoculation. Conclusion: sACE2 2 .v2.4-IgG1 has an exceptional therapeutic efficacy to SARS-CoV-2 WA-1/2020 and variant P.1 -induced acute lung vascular injury.

The accuracy of routine knee MR imaging in detection of acute neurovascular injury following multiligamentous knee injury.

To assess the accuracy of routine knee MRI in detecting acute popliteal artery and/or common peroneal nerve (CPN) dysfunction following multiligamentous knee injury (MLKI), with correlation of MRI findings to clinical outcome. Routine MRI knee examinations in 115 MLKI patients (54/115 with acute neurovascular injury, 61/115 without neurovascular injury) were retrospectively reviewed. Cases were classified by injury mechanism and ligamentous injuries sustained. MRI examinations were reviewed by two readers for vascular (arterial flow void, arterial calibre, intimal flap, perivascular hematoma) and CPN (intraneural T2-hyperintensity, calibre, discontinuity, perineural hematoma) injuries. Accuracy of routineknee MRI in the diagnosis of acute neurovascular injury and correlation of MRI findings to clinical outcome were evaluated. Patients included 86/115 males, mean age 33years. The accuracy of MRI in diagnosis of acute CPN injury was 80.6%, 83.6% (readers 1 and 2): sensitivity (78%, 79.7%), specificity (80%, 86.7%), PPV (78%, 82.5%), and NPV (82.7%, 84.4%). Increased intraneural T2 signal showed a significant correlation to acute CPN dysfunction (p < 0.05). MRI was 75%, 69.8% (readers 1 and 2) accurate in detecting acute vascular injury: sensitivity (73.3%, 86.7%), specificity (75.2%, 67.3%), PPV (30.5%, 36.1%), and NPV (95%, 97.1%). No MRI features of vascular injury showed a statistical correlation with clinical outcome. Neurovascular complications were more common in ultra-low-energy injuries and KD-V3L pattern of ligament disruption. Routine MRI is of limited accuracy in assessing vascular complication, but higher accuracy in assessing CPN injury following MLKI. Increased intraneural T2 signal on conventional knee MR imaging shows statistically significant association with clinically documented acute CPN dysfunction following MLKI.

Abstract MP12: The Epigenetic Remodeling Protein Brg1 Is Implicated In Vascular Progenitor Cell Contribution To Pathological Vascular Remodeling And Fibrosis

Vascular fibrosis is an irreversible consequence of vascular remodeling that ensues in many cardiovascular diseases. Currently, no treatments are available to target chronic vascular fibrosis. We identified a unique population of multipotent smooth muscle-derived Sca1+ progenitor cells that reside in the vascular adventitia (AdvSca1-SM cells). While AdvSca1-SM cells can differentiate into mature smooth muscle cells (SMCs) and repair the vessel wall, AdvSca1-SM cells also have the potential to differentiate into myofibroblasts and greatly contribute to vascular fibrosis after acute vascular injury. The epigenetic remodeling protein Brg1 is upregulated in AdvSca1-SM cells in the setting of vascular injury, but how Brg1 influences AdvSca1-SM differentiation is unknown. Using in vitro and in vivo approaches, our goal was to define the role of Brg1 in AdvSca1-SM cells. We hypothesized that Brg1 regulates chromatin density around genetic loci associated with fibrosis to preferentially drive AdvSca1-SM cell differentiation towards pathologic myofibroblasts. Further, we hypothesized that pharmacologic inhibition of Brg1 will disrupt AdvSca1-SM differentiation into myofibroblasts and attenuate vascular fibrosis. Mice subjected to carotid ligation and treated with the highly specific Brg1 inhibitor, PFI-3, exhibited decreased vascular fibrosis, reduced neointima, and decreased adventitial expansion of AdvSca1-SM cells as compared to mice that received vehicle control. This in vivo data was complemented by in vitro studies where cultured AdvSca1-SM cells stimulated with TGF-β expressed myofibroblast genes including αSMA and periostin, and co-treatment with PFI-3 blocked TGF-β-induced myofibroblast marker expression at the mRNA and protein level. In conclusion, these results support the hypothesis that Brg1 is a major regulator of AdvSca1-SM myofibroblast differentiation and may represent a novel targetable protein to treat vascular fibrosis.

Abstract MP28: The Bet Bromodomain Inhibitor, (+)-JQ1, Inhibits Neointima Formation Following Acute Vascular Injury Via Pten Upregulation

The primary aim of this work was to identify compounds that upregulate phosphatase and tensin homolog (PTEN) expression in smooth muscle cells (SMCs), with the expectation that PTEN upregulation would inhibit pathological vascular remodeling by promoting SMC homeostasis. Our recent work demonstrated that PTEN is an important regulator of SMC phenotype. SMC-specific PTEN deletion promotes spontaneous vascular remodeling and PTEN loss correlates with increased atherosclerotic lesion severity in human coronary arteries. In mice, PTEN overexpression reduces plaque area and preserves SMC contractile protein expression in atherosclerosis and blunts Angiotensin-II-induced pathological vascular remodeling, suggesting that pharmacologic PTEN upregulation could be a novel therapeutic approach to treat vascular disease. Currently, there are few known pharmacologic inducers of PTEN, however, we have shown that (+)-JQ1, which targets the epigenetic reader protein, Brd4, directly activates the PTEN promoter to drive PTEN expression. Mechanistically, our findings suggest that Brd4 inhibition results in p300-mediated hyper-acetylation of the PTEN promoter to increase PTEN transcriptional activity. Administration of (+)-JQ1 or SMC-specific Brd4 deletion inhibited neointima formation following acute carotid artery injury in mice. Using SMC-specific PTEN depletion both in vitro and in vivo, we showed that the observed anti-remodeling, anti-inflammatory effects were PTEN-dependent. Furthermore, we tested the effects of (+)-JQ1 on macrophage polarization, as systemic drug delivery could potentially modulate the phenotype of other resident vascular cells, including macrophages. We found that (+)-JQ1 inhibited bone marrow-derived macrophage polarization towards a pro-inflammatory phenotype, which is notable because vascular inflammation driven by SMC-macrophage cross-talk is known to promote neointima development. Importantly, our findings may hold direct clinical relevance, as BET bromodomain inhibitors related to (+)-JQ1 are currently undergoing clinical trials. These results are significant because they indicate that targeting PTEN upregulation in SMCs is a completely novel approach to inhibit vascular remodeling.

Abstract MP14: The Profibrotic Transition Of Vascular Smooth Muscle Cells-derived Resident Vascular Adventitial Progenitor Cells Contributes To Angiotensin II-induced Cardiac Fibrosis.

Cardiovascular fibrosis is an important end-stage pathology that characterizes most cardiovascular diseases. Activated cardiac myofibroblasts (MFs) are the major contributors to ECM deposition in pathological fibrosis. However, due to potential heterogeneity of MFs, the origin of these cells remains controversial. Using highly specific smooth muscle cell lineage-tracing mouse models, we discovered the smooth muscle cell origin of a subpopulation of resident vascular adventitial progenitor cells, defined by the expression of the stem cell marker Sca1 (AdvSca1-SM cells), which rapidly proliferate and adopt a myofibroblast phenotype in response to acute vascular injury. Further, we identified a specific gene signature of active hedgehog/Wnt/β-catenin/Klf4 signaling in AdvSca1-SM cells and validated a Gli1-CreERT2-ROSA26-YFP (Gli1) reporter mouse model to be a faithful lineage tracing system for AdvSca1-SM cells. However, the function of AdvSca1-SM cells in cardiac fibrosis is unknown. Using immunofluorescent staining and label-free second harmonic generation (SHG) imaging, we observed the expansion and migration of AdvSca1-SM cells in close association with perivascular and interstitial cardiac fibrosis in a model of Angiotensin II (AngII)-induced cardiac fibrosis in Gli1 reporter mice. We performed single cell RNA sequencing (scRNA-seq) to examine the phenotype of AdvSca1-SM cells in this model. Our data showed that, upon AngII challenge, AdvSca1-SM cells differentiate along a profibrotic trajectory, which is characterized by loss of expression of Klf4 , the lncRNA, Meg3 , and stemness genes and up-regulation of myofibroblast genes. Importantly, AngII-induced profibrotic transcriptomic changes of AdvSca1-SM cells were recapitulated in human ventricular tissues exhibiting a gene signature of cardiac hypertrophy, emphasizing the translational significance of this phenotypic transition. Connectivity map analysis of the scRNA-seq data identified statins as potential candidates for inhibition of the profibrotic transition of AdvSca1-SM cells. In agreement, simvastatin induced the expression of stemness genes and inhibited TGFβ-induced up-regulation of αSMA and down-regulation of Klf4 in cultured AdvSca1-SM cells.

Proximal splenic embolisation versus distal splenic embolisation for management of focal distal arterial injuries of the spleen.

To compare the outcomes of proximal (pSAE) versus distal (dSAE) splenic artery embolisation for management of focal distal arterial splenic injuries secondary to blunt splenic trauma. Ethical approval was granted by the hospital research and ethics committee, Project 389/19. All patients who underwent splenic artery embolisation secondary to blunt abdominal trauma from 1 January 2009 to 1 January 2019 were reviewed. Patients with a tandem embolisation (both proximal and distal embolisations) or those with no acute vascular injury on angiography were excluded. Patient demographics, injury type/ AAST grade (2018 classification), technique of embolisation and outcomes were collected. Complications and splenectomy rates up to 30 days were recorded. 136 out of 232 patients had an embolisation performed for a distal vascular injury including active arterial bleeding, pseudoaneurysm or arteriovenous fistula. Mean age was 41 (range 16-84). Mean AAST grade was 4 (range 3-5). Mean Injury Severity Score was 22. pSAE was performed in 79.4% (n = 108) and dSAE in 20.6% (n = 28). Major complications occurred in 12 patients (pSAE n = 12, 11.1%; dSAE n = 0, P > 0.05); 6 pSAE required splenectomy (n = 6, 5.6%). There was no significant difference in outcomes between the two groups or when based on AAST grading. No significant difference was observed between proximal and distal embolisation techniques for blunt trauma patients with a distal vascular injury in terms of technical and clinical success.

Heterogeneous subpopulations of adventitial progenitor cells regulate vascular homeostasis and pathological vascular remodelling.

Cardiovascular diseases are characterized by chronic vascular dysfunction and provoke pathological remodelling events, such as neointima formation, atherosclerotic lesion development, and adventitial fibrosis. While lineage-tracing studies have shown that phenotypically modulated smooth muscle cells (SMCs) are the major cellular component of neointimal lesions, the cellular origins and microenvironmental signalling mechanisms that underlie remodelling along the adventitial vascular layer are not fully understood. However, a growing body of evidence supports a unique population of adventitial lineage-restricted progenitor cells expressing the stem cell marker, stem cell antigen-1 (Sca1; AdvSca1 cells) as important effectors of adventitial remodelling and suggests that they are at least partially responsible for subsequent pathological changes that occur in the media and intima. AdvSca1 cells are being studied in murine models of atherosclerosis, perivascular fibrosis, and neointima formation in response to acute vascular injury. Depending on the experimental conditions, AdvSca1 cells exhibit the capacity to differentiate into SMCs, endothelial cells, chondrocytes, adipocytes, and pro-remodelling cells, such as myofibroblasts and macrophages. These data indicate that AdvSca1 cells may be a targetable cell population to influence the outcomes of pathologic vascular remodelling. Important questions remain regarding the origins of AdvSca1 cells and the essential signalling mechanisms and microenvironmental factors that regulate both maintenance of their stem-like, progenitor phenotype and their differentiation into lineage-specified cell types. Adding complexity to the story, recent data indicate that the collective population of adventitial progenitor cells is likely composed of several smaller, lineage-restricted subpopulations, which are not fully defined by their transcriptomic profile and differentiation capabilities. The aim of this review is to outline the heterogeneity of Sca1+ adventitial progenitor cells, summarize their role in vascular homeostasis and remodelling, and comment on their translational relevance in humans.

Impact of Fever Prevention in Brain-Injured Patients (INTREPID): Study Protocol for a Randomized Controlled Trial

Multiple studies demonstrate that fever/elevated temperature is associated with poor outcomes in patients with vascular brain injury; however, there are no conclusive studies that demonstrate that fever prevention/controlled normothermia is associated with better outcomes. The primary objective of the INTREPID (Impact of Fever Prevention in Brain-Injured Patients) trial is to test the hypothesis that fever prevention is superior to standard temperature management in patients with acute vascular brain injury. INTREPID is a prospective randomized open blinded endpoint study of fever prevention versus usual care in patients with ischemic or hemorrhagic stroke. The fever prevention intervention utilizes the Arctic Sun System and will be compared to standard care patients in whom fever may spontaneously develop. Ischemic stroke, intracerebral hemorrhage or subarachnoid hemorrhage patients will be included within disease-specific time-windows. Both awake and sedated patients will be included, and treatment is initiated immediately upon enrollment. Eligible patients are expected to require intensive care for at least 72h post-injury, will not be deemed unlikely to survive without severe disability, and will be treated for up to 14days, or until deemed ready for discharge from the ICU, whichever comes first. Fifty sites in the USA and worldwide will participate, with a target enrollment of 1176 patients (1000 evaluable). The target temperature is 37.0°C. The primary efficacy outcome is the total fever burden by °C-h, defined as the area under the temperature curve above 37.9°C. The primary secondary outcome, on which the sample size is based, is the modified Rankin Scale Score at 3months. All efficacy analyses including the primary and key secondary endpoints will be primarily based on an intention-to-treat population. Analysis of the as-treated and per protocol populations will also be performed on the primary and key secondary endpoints as sensitivity analyses. The INTREPID trial will provide the first results of the impact of a pivotal fever prevention intervention in patients with acute stroke ( www.clinicaltrials.gov ; NCT02996266; registered prospectively 05DEC2016).

Chemotherapy-induced acute vascular injury involves intracellular generation of ROS via activation of the acid sphingomyelinase pathway

Several categories of chemotherapy confer substantial risk for late-term vascular morbidity and mortality. In the present study, we aimed to investigate the mechanism of acute chemotherapy-induced vascular injury in normal tissues. Specifically, we looked at activation of the acid sphingomyelinase (ASMase)/ceramide pathway, which leads to generation of reactive oxygen species (ROS) and induction of oxidative stress that may result in vascular injury.In particular, we focused on two distinct drugs, doxorubicin (DOX) and cisplatin (CIS) and their effects on normal endothelial cells. In vitro, DOX resulted in increased ASMase activity, intra-cellular ROS production and induction of apoptosis. CIS treatment generated significantly reduced effects in endothelial cells. In-vivo, murine femoral arterial blood flow was measured in real-time, during and after DOX or CIS administration, using fluorescence optical imaging system. While DOX caused constriction of small vessels and disintegration of large vessels' wall, CIS induced minor vascular changes in arterial blood flow, correlating with the in vitro findings. These results demonstrate that DOX induces acute vascular injury by increased ROS production, via activation of ASMase/ceramide pathway, while CIS increases ROS production and its immediate extracellular translocation, without causing detectable acute vascular injury. Our findings may potentially lead to the development of new strategies to prevent long-term cardiovascular morbidity in cancer survivors.

Acute exercise-induced glycocalyx shedding does not differ between exercise modalities, but is associated with total antioxidative capacity

ObjectivesRegular physical exercise is known to protect endothelial integrity. It has been proposed that acute exercise-induced changes of the (anti-)oxidative system influence early (glycocalyx shedding) and sustained endothelial activation (shedding of endothelial cells, ECs) as well as endothelial-cell repair by circulating hematopoietic stem and progenitor cells (HPCs). However, results are not conclusive and data in trained participants performing different exercise modalities is lacking. DesignEighteen healthy, well-trained participants (9 runners, 9 cyclists; age: 29.7 ± 4.2 yrs) performed a strenuous acute exercise session consisting of 4 bouts of 4-min high-intensity with decreasing power profile and 3-min low-intensity in-between. MethodsAverage power/speed of intense phases was 85% of the peak achieved in a previous incremental test. Before and shortly after exercise, total oxidative and antioxidative capacities (TAC), shedding of syndecan-1, heparan sulfate, hyaluronan, ECs, and circulating HPCs were investigated. ResultsTAC decreased from 1.81 ± 0.42 nmol/L to 1.47 ± 0.23 nmol/L post-exercise (p = 0.010) only in runners. Exercise-induced early and sustained endothelial activation were enhanced post-exercise- syndecan-1: 103.2 ± 63.3 ng/mL to 111.3 ± 71.3 ng/mL, heparan sulfate: from 2637.9 ± 800.1 ng/mL to 3197.1 ± 1416.3 ng/mL, both p < 0.05; hyaluronan: 84.3 ± 21.8 ng/mL to 121.4 ± 29.4 ng/mL, ECs: from 6.6 ± 4.5 cells/μL to 9.5 ± 6.2 cells/μL, both p < 0.01; results were not different between exercise modalities and negatively related to TAC concentrations post-exercise. HPC proportions and self-renewal ability were negatively, while EC concentrations were positively associated with circulating hyaluronan concentrations. ConclusionsThese results highlight the importance of the antioxidative system to prevent the endothelium from acute exercise-induced vascular injury – independent of exercise modality – in well-trained participants. Endothelial-cell repair is associated with hyluronan signaling, possibly a similar mechanism as in wound repair.

Anti-inflammatory Effects of Statins in Lung Vascular Pathology: From Basic Science to Clinical Trials.

HMG-CoA reductase inhibitors (or statins) are cholesterol-lowering drugs and are among the most widely prescribed medications in the United States. Statins exhibit pleiotropic effects that extend beyond cholesterol reduction including anti-atherosclerotic, antiproliferative, anti-inflammatory, and antithrombotic effects. Over the last 20years, statins have been studied and examined in pulmonary vascular disorders, including both chronic pulmonary vascular disease such as pulmonary hypertension, and acute pulmonary vascular endothelial injury such as acute lung injury. In both research and clinical settings, statins have demonstrated promising vascular protection through modulation of the endothelium, attenuation of vascular leak, and promotion of endothelial repair following lung inflammation. This chapter provides a summary of the rapidly changing literature, summarizes the anti-inflammatory mechanism of statins on pulmonary vascular disorders, and explores clinical evidence for statins as a potential therapeutic approach to modulation of the endothelium as well as a means to broaden our understanding of pulmonary vasculopathy pathophysiology.

Dynamic Changes in Resolution Circuits after Acute Vascular Injury Highlight an Early Resolution Deficit

Dynamic Changes in Resolution Circuits after Acute Vascular Injury Highlight an Early Resolution Deficit

A Human Vascular Injury-on-a-Chip Model of Hemostasis.

Hemostasis is an innate protective mechanism that plays a central role in maintaining the homeostasis of the vascular system during vascular injury. Studying this essential physiological process is often challenged by the difficulty of modeling and probing the complex dynamics of hemostatic responses in the native context of human blood vessels. To address this major challenge, this paper describes a microengineering approach for in vitro modeling of hemostasis. This microphysiological model replicates the living endothelium, multilayered microarchitecture, and procoagulant activity of human blood vessels, and is also equipped with a microneedle that is actuated with spatial precision to simulate penetrating vascular injuries. The system recapitulates key features of the hemostatic response to acute vascular injury as observed in vivo, including i) thrombin-driven accumulation of platelets and fibrin, ii) formation of a platelet- and fibrin-rich hemostatic plug that halts blood loss, and iii) matrix deformation driven by platelet contraction for wound closure. Moreover, the potential use of this model for drug testing applications is demonstrated by evaluating the effects of anticoagulants and antiplatelet agents that are in current clinical use. The vascular injury-on-a-chip may serve as an enabling platform for preclinical investigation of hematological disorders and emerging therapeutic approaches against them.