Atherosclerosis, a hyperlipidemia-induced chronic inflammatory process of the arterial wall, develops preferentially at sites where disturbed laminar flow compromises endothelial cell (EC) function. Here we show that endothelial miR-126-5p maintains a proliferative reserve in ECs through suppression of the Notch1 inhibitor delta-like 1 homolog (Dlk1) and thereby prevents atherosclerotic lesion formation. Endothelial recovery after denudation was impaired in Mir126−/− mice because lack of miR-126-5p, but not miR-126-3p, reduced EC proliferation by derepressing Dlk1. At nonpredilection sites, high miR-126-5p levels in endothelial cells confer a proliferative reserve that compensates for the antiproliferative effects of hyperlipidemia, such that atherosclerosis was exacerbated in Mir126−/− mice. In contrast, downregulation of miR-126-5p by disturbed flow abrogated EC proliferation at predilection sites in response to hyperlipidemic stress through upregulation of Dlk1 expression. Administration of miR-126-5p rescued EC proliferation at predilection sites and limited atherosclerosis, introducing a potential therapeutic approach.

Macrophages in atherosclerotic plaques drive inflammatory responses, degrade lipoproteins, and phagocytose dead cells. MicroRNAs (miRs) control the differentiation and activity of macrophages by regulating the signaling of key transcription factors. However, the functional role of macrophage-related miRs in the immune response during atherogenesis is unknown. Here, we report that miR-155 is specifically expressed in atherosclerotic plaques and proinflammatory macrophages, where it was induced by treatment with mildly oxidized LDL (moxLDL) and IFN-γ. Leukocyte-specific Mir155 deficiency reduced plaque size and number of lesional macrophages after partial carotid ligation in atherosclerotic (Apoe -/-) mice. In macrophages stimulated with moxLDL/IFN-γ in vitro, and in lesional macrophages, loss of Mir155 reduced the expression of the chemokine CCL2, which promotes the recruitment of monocytes to atherosclerotic plaques. Additionally, we found that miR-155 directly repressed expression of BCL6, a transcription factor that attenuates proinflammatory NF-κB signaling. Silencing of Bcl6 in mice harboring Mir155 -/-macrophages enhanced plaque formation and CCL2 expression. Taken together, these data demonstrated that miR-155 plays a key role in atherogenic programming of macrophages to sustain and enhance vascular inflammation.

Enhanced permeability and retention (EPR), and the (over-) expression of angiogenesis-related surface receptors are key features of tumor blood vessels. As a consequence, EPR-mediated passive and RGD-and NGR-based active tumor targeting have received considerable attention in the last couple of years. Using several different in vivo and ex vivo optical imaging techniques, we here visualized and quantified the benefit of RGD-and NGR-based vascular vs. EPR-mediated passive tumor targeting. This was done using ~10 nm-sized polymeric nanocarriers, which were either labeled with DY-676 (peptide-modified polymers) or with DY-750 (peptide-free polymers). Upon co-injection into mice bearing both highly leaky CT26 and poorly leaky BxPC3 tumors, it was found that vascular targeting did work, resulting in rapid and efficient early binding to tumor blood vessels, but that over time, passive targeting was significantly more efficient, leading to higher overall levels and to more efficient retention within tumors. Although this situation might be different for larger carrier materials, these insights indicate that caution should be taken not to over-estimate the potential of active over passive tumor targeting. KeywordsNanomedicine; Drug targeting; EPR; RGD; NGR Paralleled by the ever-increasing advances in nanotechnology and chemical engineering, nanomedicine formulations have started to attract significant attention in the last couple of years. Nanomedicines are 1-100(0) nm-sized carrier materials designed to improve the biodistribution and target site accumulation of low-molecular-weight (chemo-) therapeutic agents. By means of both passive and active targeting mechanisms, nanocarrier materials * Corresponding Authors Prof. Dr. Fabian Kiessling; Tel: +49-241-8080116; fkiessling@ukaachen.de Dr. Dr. Twan Lammers; Tel: +49-241-8036681; tlammers@ukaachen.de. Supporting Information Materials and methods describing the synthesis and characterization of the polymeric nanocarriers are provided as supplementary information. This material is available free of charge via the Internet at http://pubs.acs.org. Europe PMC Funders GroupAuthor Manuscript Nano Lett. Author manuscript; available in PMC 2014 March 04. Published in final edited form as:Nano Lett. 2014 February 12; 14(2): 972-981. doi:10.1021/nl404391r. Europe PMC Funders Author ManuscriptsEurope PMC Funders Author Manuscripts aim to more efficiently deliver drug molecules to pathological sites, while at the same time preventing their accumulation in potentially endangered healthy tissues, thereby beneficially affecting the balance between their efficacy and toxicity 1-4 .Passive drug targeting relies on the hyper-permeable tumor vasculature. Endothelial gaps and improperly aligned vascular endothelium result in leaky blood vessels, which enable the extravasation of carrier materials with sizes of up to several 100's of nm into the tumor interstitium. In addition to this, dysfunctional lymphatic drainage results in the retention of extravasated nanomaterials within tumo...

Objectives-In chronic liver injury, angiogenesis, the formation of new blood vessels from preexisting ones, may contribute to progressive hepatic fibrosis and to development of hepatocellular carcinoma. Although hypoxia-induced expression of vascular endothelial growth factor (VEGF) occurs in advanced fibrosis, we hypothesized that inflammation may endorse hepatic angiogenesis already at early stages of fibrosis.Design-Angiogenesis in livers of c57BL/6 mice upon carbon tetrachloride (CCl 4 ) or bile duct ligation (BDL) induced chronic hepatic injury was non-invasively monitored using in vivo contrast-enhanced micro-computed tomography (CT) and ex vivo anatomical μCT after hepatic Microfil perfusion. Functional contributions of monocyte-derived macrophage subsets for angiogenesis were explored by pharmacological inhibition of CCL2 using the Spiegelmer mNOX-E36.Results-Contrast-enhanced in vivo μCT imaging allowed non-invasively monitoring the close correlation of angiogenesis, reflected by functional hepatic blood vessel expansion, with experimental fibrosis progression. On a cellular level, inflammatory monocyte-derived

The combination of target-specific drugs like bevacizumab with chemotherapeutics has improved treatment efficacy in advanced colorectal cancer (CRC). However, the clinical prognosis of metastatic CRCs is still poor, and novel drugs are currently assessed with respect to their efficacies in patients with CRCs. In a phase III study, the multikinase inhibitor regorafenib has recently been shown to prolong survival of patients with CRCs after standard therapies failed. In the present study, the activity of regorafenib was investigated in comparison with the angiogenesis inhibitor DC101 in the highly aggressive, murine CT26 metastatic colon cancer model. While a treatment for 10 days with DC101 given at a dose of 34 mg/kg every third day significantly delayed tumor growth compared with vehicle-treated animals, regorafenib completely suppressed tumor growth at a daily oral dose of 30 mg/kg. Regorafenib also induced a stronger reduction in tumor vascularization, as longitudinally assessed in vivo by dynamic contrast-enhanced MRI (DCE-MRI) and confirmed by immunohistochemistry. In addition, regorafenib inhibited the angiogenic activity more strongly and induced a three times higher apoptosis rate than DC101. Even more important, regorafenib completely prevented the formation of liver metastases, whereas in DC101-treated animals, the metastatic rate was only reduced by 33% compared with the vehicle group. In addition, regorafenib significantly reduced the amount of infiltrating macrophages. These data show that the multikinase inhibitor regorafenib exerts strong antiangiogenic, antitumorigenic, and even antimetastatic effects on highly aggressive colon carcinomas indicative for its high potential in the treatment of advanced CRCs.