Rodent models of pulmonary embolism and chronic thromboembolic pulmonary hypertension

Pulmonary embolism (PE) is the third most prevalent cardiovascular disease. It is associated with high in-hospital mortality and the development of acute and chronic complications. New approaches aimed at improving the prognosis of patients with PE are largely dependent on reliable animal models. Mice, rats, hamsters, and rabbits, are currently most commonly used for PE modeling because of their ethical acceptability and economic feasibility. This article provides an overview of the main approaches to PE modeling, and the advantages and disadvantages of each method. Special attention is paid to experimental endpoints, including morphological, functional, and molecular endpoints. All approaches to PE modeling can be broadly divided into three main groups: 1) induction of thromboembolism, either by thrombus formation in vivo or by injection of in vitro prepared blood clots; 2) introduction of particles of non-thrombotic origin; and 3) surgical procedures. The choice of a specific model and animal species is determined based on the objectives of the study. Rodent models of chronic thromboembolic pulmonary hypertension (CTEPH), which is the most devastating complication of PE, are also described. CTEPH models are especially challenging because of insufficient knowledge about the pathogenesis and high fibrinolytic activity of rodent plasma. The CTEPH model should demonstrate a persistent increase in pulmonary artery pressure and stable reduction of the vascular bed due to recurrent embolism. Based on the analysis of available evidence, one might conclude that currently, there is no single optimal method for modeling PE and CTEPH.

JANEX-1 improves acute pulmonary embolism through VEGF and FAK in pulmonary artery smooth muscle cells

IMPACT STATEMENT

Accumulating evidence suggests that vascular remodeling due to immoderate proliferation and migration of SMCs is a common process occurring in APE. In this work, we tried to find a breakthrough in the pathological mechanism to alleviate the prognosis of APE by improving SMCs proliferation and explored the effect of JANEX-1 on PDGF-induced proliferation-related molecules in PVSMCs and assessed the therapeutic potential of JAK3 for vascular remodeling in APE mice. We demonstrated that JANEX-1, blocking JAK3 expression or activity, reduced JAK3/STAT3 signaling pathway, VEGF expression and FAK activation, and PDGF-induced proliferation of PVSMCs. Moreover, JANEX-1 inhibited the thrombus-induced intimal hyperplasia and the expression of VEGF and FAK activation in neointimal SMCs of APE mice. The data are helpful to elucidate the pharmacological mechanism and potential therapeutic effect of JANEX-1 in APE.

High-Mobility Group Box 1 (HMGB1) Induces Migration of Endothelial Progenitor Cell via Receptor for Advanced Glycation End-Products (RAGE)-Dependent PI3K/Akt/eNOS Signaling Pathway

BACKGROUND High-mobility group box1 (HMGB1) is a cytokine that has been demonstrated to have an important role in inducing migration and homing of endothelial progenitor cells (EPCs) in the process of neovascularization during wound healing, but its specific mechanism remains elusive. The aim of this study was to investigate the effects of the HMGB-RAGE axis in EPC migration, as well as the underlying molecular mechanism responsible for these effects. MATERIAL AND METHODS EPCs were isolated from the mice and identified using flow cytometry and fluorescence staining. The effect of HMGB1 on the activity of EPCs was detected using the Cell Counting Kit-8 (CCK-8). Then, the migration of EPCs was detected by scratch wound-healing and cell migration assay. NO levels were analyzed by ELISA. The expression of p-PI3K, p-Akt, and p-eNOS was determined by Western blot analysis. RAGE expression was measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot analysis. F-actin was assessed by fluorescent staining. RESULTS The results showed that HMGB1 induced a concentration-dependent migration of EPCs, and the migration was RAGE-dependent. The migration could be almost completely blocked by PI3K inhibitors and eNOS inhibitor. HMGB1-RAGE upregulated the expression of p-Akt, p-eNOS, and p-ERK. We also demonstrated that the MEK/ERK signaling pathway is not involved in the EPC migration induced by HMGB1-RAGE. CONCLUSIONS These data demonstrate that HMGB1 activates RAGE and induces PI3K/Akt/eNOS signaling transduction pathway activation to promote EPC migration. Therefore, the HMGB1-RAGE axis plays an important role in the EPC migration process and may become a potential target in wound healing.

Angiogenic Factor AGGF1-Primed Endothelial Progenitor Cells Repair Vascular Defect in Diabetic Mice

Hyperglycemia-triggered vascular abnormalities are the most serious complications of diabetes mellitus (DM). The major cause of vascular dysfunction in DM is endothelial injury and dysfunction associated with the reduced number and dysfunction of endothelial progenitor cells (EPCs). A major challenge is to identify key regulators of EPCs to restore DM-associated vascular dysfunction. We show that EPCs from heterozygous knockout Aggf1^+/- mice presented with impairment of proliferation, migration, angiogenesis, and transendothelial migration as in hyperglycemic mice fed a high-fat diet (HFD) or db/db mice. The number of EPCs from Aggf1^+/- mice was significantly reduced. Ex vivo, AGGF1 protein can fully reverse all damaging effects of hyperglycemia on EPCs. In vivo, transplantation of AGGF1-primed EPCs successfully restores blood flow and blocks tissue necrosis and ambulatory impairment in HFD-induced hyperglycemic mice or db/db mice with diabetic hindlimb ischemia. Mechanistically, AGGF1 activates AKT, reduces nuclear localization of Fyn, which increases the nuclear level of Nrf2 and expression of antioxidative genes, and inhibits reactive oxygen species generation. These results suggest that Aggf1 is required for essential function of EPCs, AGGF1 fully reverses the damaging effects of hyperglycemia on EPCs, and AGGF1 priming of EPCs is a novel treatment modality for vascular complications in DM.

Bioinformatics-based study to detect chemical compounds that show potential as treatments for pulmonary thromboembolism

The objectives of the present study comprised the recognition of major genes related to pulmonary thromboembolism (PTE) and the evaluation of their functional enrichment levels, in addition to the identification of small chemical molecules that may offer potential for use in PTE treatment. The RNA expression profiling of GSE84738 was obtained from the Gene Expression Omnibus database. Following data preprocessing, the differently expressed genes (DEGs) between the PTE group and the control group were identified using the Linear Models for Microarray package. Subsequently, the protein‑protein interaction (PPI) network of these DEGs was examined using the Search Tool for the Retrieval of Interacting Genes/Proteins database, visualized via Cytoscape. The most significantly clustered modules in the network were identified using Multi Contrast Delayed Enhancement, a plugin of Cytoscape. Subsequently, functional enrichment analysis of the DEGs was performed, using the Database for Annotation Visualization and Integrated Discovery tool. Furthermore, the chemical‑target interaction networks were investigated using the Comparative Toxicogenomics Database as visualized via Cytoscape. A total of 548 DEGs (262 upregulated and 286 downregulated) were identified in the PTE group, compared with the control group. The upregulated and downregulated genes were enriched in Gene Ontology terms related to inflammation and eye sarcolemma, respectively. Tumor necrosis factor (TNF) and erb‑b2 receptor tyrosine kinase 2 (ERBB2) were upregulated genes that ranked higher in the PPI network (47 and 40 degrees, respectively) whereas C‑JUN was the most downregulated gene (46). Small chemical molecules ethinyl (135), cyclosporine (126), thrombomodulin precursor (113) and tretinoin (111) had >100 degrees in the DEG‑chemical interaction network. In addition, ethinyl targeted to TNF, whereas TNF and ERBB2 were targeted by cyclosporine, and tretinoin was a targeted chemical of ERBB2. Therefore, cyclosporine, ethinyl, and tretinoin may be potential targets for PTE treatment.

Crocetin restores diabetic endothelial progenitor cell dysfunction by enhancing NO bioavailability via regulation of PI3K/AKT-eNOS and ROS pathways

AIMS

Endothelial progenitor cell (EPC) dysfunction underlies a critical risk factor in diabetic vascular complications due to function defect in restoring endothelium injury. Crocetin has attracted increasing attention in several vascular-related diseases. In present study, we aimed to explore the role of crocetin in diabetic EPC dysfunction.

MAIN METHODS

EPCs were isolated from bone marrow in diabetic mice and identified using the fluorescence staining and flow cytometry. After exposure to various doses of crocetin, cell viability was detected by MTT assy. Then, colony formation, lactate dehydrogenase (LDH) release, cell apoptosis and caspase-3 activity were assessed. The underlying mechanism was also investigated by western blotting.

KEY FINDINGS

EPCs from diabetic mice exhibited dysfunction under hyperglycemia condition. Interestingly, crocetin treatment alleviated the impairment in diabetic EPC proliferation and colony formation. Simultaneously, the increases in LDH release, cell apoptosis and caspase-3 activity were also restrained following crocetin stimulation. Additionally, EPC migration response to SDF-1 was also impaired under diabetic condition, which was partly restored by crocetin. Mechanism analysis manifested that administration with crocetin repaired the damage in the activation of PI3K/AKT-eNOS pathway and NO production, but attenuated ROS elevation in diabetic EPCs. Importantly, preconditioning with antagonist of LY294002 (for PI3K/AKT) or N^G-monomethyl-l-arginine (for eNOS) antagonized the beneficial effect of crocetin on diabetic EPC dysfunction.

SIGNIFICANCE

These data corroborated that crocetin could restore the dysfunction of diabetic EPCs by enhancing NO bioavailability via regulation of PI3K/AKT-eNOS and ROS pathways. Therefore, this research supports a potential promising therapeutic aspect for diabetic patients.

Gene Expression Profiling of Pulmonary Artery in a Rabbit Model of Pulmonary Thromboembolism

Acute pulmonary thromboembolism (PTE) refers to the obstruction of thrombus in pulmonary artery or its branches. Recent studies have suggested that PTE-induced endothelium injury is the major physiological consequence of PTE. And it is reasonal to use PTE-induced endothelium injury to stratify disease severity. According to the massive morphologic and histologic findings, rabbit models could be applied to closely mimic the human PE. Genomewide gene expression profiling has not been attempted in PTE. In this study, we determined the accuracy of rabbit autologous thrombus PTE model for human PTE disease, then we applied gene expression array to identify gene expression changes in pulmonary arteries under PTE to identify potential molecular biomarkers and signaling pathways for PTE. We detected 1343 genes were upregulated and 923 genes were downregulated in PTE rabbits. The expression of several genes (IL-8, TNF-α, and CXCL5) with functional importance were further confirmed in transcript and protein levels. The most significantly differentially regulated genes were related to inflammation, immune disease, pulmonary disease, and cardiovascular diseases. Totally 87 genes were up-regulated in the inflammatory genes. We conclude that gene expression profiling in rabbit PTE model could extend the understanding of PTE pathogenesis at the molecular level. Our study provides the fundamental framework for future clinical research on human PTE, including identification of potential biomarkers for prognosis or therapeutic targets for PTE.

Statins, HMG-CoA Reductase Inhibitors, Improve Neovascularization by Increasing the Expression Density of CXCR4 in Endothelial Progenitor Cells

Statins, inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, are used to reduce cholesterol biosynthesis in the liver. Accordingly, statins regulate nitric oxide (NO) and glutamate metabolism, inflammation, angiogenesis, immunity and endothelial progenitor cells (EPCs) functions. The function of EPCs are regulated by stromal cell-derived factor 1 (SDF-1), vascular endothelial growth factor (VEGF), and transforming growth factor β (TGF-β), etc. Even though the pharmacologic mechanisms by which statins affect the neovasculogenesis of circulating EPCs, it is still unknown whether statins affect the EPCs function through the regulation of CXCR4, a SDF-1 receptor expression. Therefore, we desired to explore the effects of statins on CXCR4 expression in EPC-mediated neovascularization by in vitro and in vivo analyses. In animal studies, we analyzed the effects of atorvastatin or rosuvastatin treatments in recovery of capillary density and blood flow, the expression of vWF and CXCR4 at ischemia sites in hindlimb ischemia ICR mice. Additionally, we analyzed whether the atorvastatin or rosuvastatin treatments increased the mobilization, homing, and CXCR4 expression of EPCs in hindlimb ischemia ICR mice that underwent bone marrow transplantation. The results indicated that statins treatment led to significantly more CXCR4-positive endothelial progenitor cells incorporated into ischemic sites and in the blood compared with control mice. In vivo, we isolated human EPCs and analyzed the effect of statins treatment on the vasculogenic ability of EPCs and the expression of CXCR4. Compared with the control groups, the neovascularization ability of EPCs was significantly improved in the atorvastatin or rosuvastatin group; this improvement was dependent on CXCR4 up-regulation. The efficacy of statins on improving EPC neovascularization was related to the SDF-1α/CXCR4 axis and might be regulated by the NO. In conclusion, atorvastatin and rosuvastatin improved neovascularization in hindlimb ischemia mice; this effect may have been mediated by increased CXCR4 expression in EPCs.

Calvarial defect healing by recruitment of autogenous osteogenic stem cells using locally applied simvastatin

Local statins implant has been shown to promote bone healing, the underlying mechanisms are unclear. The purpose of this study was to test the effect of local simvastatin implant on bone defect healing; to evaluate the mobilization, migration, and homing of bone marrow-derived mesenchymal stem cells (BMSCs) and endothelial progenitor cells (EPCs) induced by simvastatin. We found that local simvastatin implant increased bone formation by 51.8% (week 6) and 64.8% (week 12) compared with polyglycolic acid controls (P < 0.01), as verified by X-ray, CT, and histology. Simvastatin increased migration capacity of BMSCs and EPCs in vitro (P < 0.05). Local simvastatin implant increased mobilization of EPCs to the peripheral blood by 127% revealed by FACS analysis (P < 0.01), and increased osteogenic BMSCs to the peripheral blood dramatically revealed by Alizarin Red-S staining for mineralized nodules formation. Pre-transplanted GFP-transfected BMSCs as a tracing cell and bioluminescence imaging revealed that local simvastatin implant recruited GFP-labeled BMSC. Also, local simvastatin implant induced the HIF-1α and BMP-2 expression. In conclusion, local simvastatin implantation promotes bone defect healing, where the underlying mechanism appears to involve the higher expression of HIF-1α and BMP-2, thus recruit autogenous osteogenic and angiogenetic stem cells to the bone defect area implanted with simvastatin.