Ruiming Liu

MCP-1 Stimulates MMP-9 Expression via ERK 1/2 and p38 MAPK Signaling Pathways in Human Aortic Smooth Muscle Cells

Objective: We investigated the molecular mechanism underlying the role of monocyte chemoattractant protein-1 (MCP-1) in the formation and development of human abdominal aortic aneurysm (AAA). Methods: We examined protein expression profiles using a protein array and found that MCP-1 was the most highly expressed protein in AAA tissues compared with normal aortas. To investigate the potential mechanism of MCP-1 involvement in the pathogenesis of AAA, we treated human aortic smooth muscle cells (HASMCs) with human recombinant MCP-1. Results: MCP-1 was the most highly expressed protein in AAA tissues compared with normal aorta; matrix metalloproteinase-9 (MMP-9) expression was also significantly increased. Treatment with MCP-1 significantly increased the expression and activation of MMP-9 and activated the three major mitogen activated protein kinases (MAPKs) extracellular signal regulated kinase (ERK), c-Jun amino terminal kinase (JNK1/2) and p38 MAPK. Furthermore, MCP-1-induced secretion of MMP-9 was inhibited by U0126 (inhibitor of the ERK 1/2 pathway) and SB203580 (inhibitor of the p38 MAPK pathway), but not SP600125 (inhibitor of the JNK1/2 pathway). Conclusion: These data demonstrate that MCP-1 stimulates secretion of MMP-9 directly through the ERK1/2 and p38 MAPK mediated pathways in HASMCs. Thus, inhibition of this molecular mechanism might be a potential therapeutic target in the non-surgical treatment of AAA.

The Preparation and Performance of a New Polyurethane Vascular Prosthesis

We investigated the performance of small-caliber polyurethane (PU) small-diameter vascular prosthesis generated using the electrospinning technique. PU was electrospun into small-diameter, small-caliber tubular scaffolds for potential application as vascular grafts. We investigated the effects of electrospinning conditions (solution concentration, mandrel rotation speed) on the microstructure and porosity of the scaffolds for the purpose of preparing scaffolds with optimum microstructures and properties. We evaluated the mechanical properties of the scaffolds by tensile tests and the cytotoxicity of the PU small-diameter, small-caliber PU synthetic vascular graft by the MTT assay. The adhesion of endothelial cells to the PU scaffold was characterized by Hoechst staining and fluorescence microscopy, and we measured endothelial cell proliferation on the PU scaffold by the CCK-8 assay. We analyzed the prosthesis microstructure and endothelial cell morphology using scanning electron microscopy. With increasing PU concentration in the electrospinning solution, the fiber diameter of the vascular graft increased and the porosity decreased. In addition, with increasing electrospinning time, the wall thickness increased and the porosity decreased. We found that regular fiber orientation can be obtained by adjusting the rotation speed of the mandrel. Cell proliferation was not inhibited as the small-caliber PU synthetic vascular grafts showed little cytotoxicity. The endothelial cells had faster adherence to the PU scaffolds than to the PTFE surface during the initial contact. After prolonged cell culture, significantly higher endothelial cell proliferation rate was observed in the PU scaffold groups than the PTFE group. We obtained small-caliber PU vascular grafts with optimal fiber arrangement, excellent mechanical properties, and optimal biocompatibility by optimizing the electrospinning conditions. This study provides in vitro biocompatibility data that is helpful for the clinical application of the PU small-diameter, small-caliber PU vascular grafts.

The in vivo performance of small-caliber nanofibrous polyurethane vascular grafts.

BackgroundIn a previous in vitro study, we confirmed that small-caliber nanofibrous polyurethane (PU) vascular grafts have favorable mechanical properties and biocompatibility. In the present study, we examined the in vivo biocompatibility and stability of these grafts.MethodsForty-eight adult male beagle dogs were randomly divided into two groups receiving, respectively, polyurethane (PU) or polytetrafluoroethylene (PTFE) grafts (n = 24 animals / group). Each group was studied at 4, 8, 12, and 24 weeks after graft implantation. Blood flow was analyzed by color Doppler ultrasound and computed tomography angiography. Patency rates were judged by animal survival rates. Coverage with endothelial and smooth muscle cells was characterized by hematoxylin-eosin and immunohistological staining, and scanning electron microscopy (SEM).ResultsPatency rates were significantly higher in the PU group (p = 0.02 vs. PTFE group). During the first 8 weeks, endothelial cells gradually formed a continuous layer on the internal surface of PU grafts, whereas coverage of PTFE graft by endothelial cells was inhomogeneous. After 12 weeks, neointimal thickness remained constant in the PU group, while PTFE group showed neointimal hyperplasia. At 24 weeks, some anastomotic sites of PTFE grafts became stenotic (p = 0.013 vs. PU group). Immunohistological staining revealed a continuous coverage by endothelial cells and an orderly arrangement of smooth muscle cells on PU grafts. Further, SEM showed smooth internal surfaces in PU grafts without thrombus or obvious neointimal hyperplasia.ConclusionsSmall-caliber nanofibrous PU vascular grafts facilitate the endothelialization process, prevent excessive neointimal hyperplasia, and improve patency rates.

MiR-142-3p Attenuates the Migration of CD4+ T Cells through Regulating Actin Cytoskeleton via RAC1 and ROCK2 in Arteriosclerosis Obliterans

The migration of CD4+ T cells plays an important role in arteriosclerosis obliterans (ASO). However, the molecular mechanisms involved in CD4+ T cell migration are still unclear. The current study is aimed to determine the expression change of miR-142-3p in CD4+ T cells from patients with ASO and investigate its role in CD4+ T cell migration as well the potential mechanisms involved. We identified by qRT-PCR and in situ hybridization that the expression of miR-142-3p in CD4+ T cells was significantly down-regulated in patients with ASO. Chemokine (C-X-C motif) ligand 12 (CXCL12), a common inflammatory chemokine under the ASO condition, was able to down-regulate the expression of miR-142-3p in cultured CD4+ T cells. Up-regulation of miR-142-3p by lentivirus-mediated gene transfer had a strong inhibitory effect on CD4+ T cell migration both in cultured human cells in vitro and in mouse aortas and spleens in vivo. RAC1 and ROCK2 were identified to be the direct target genes in human CD4+ T cells, which are further confirmed by dual luciferase assay. MiR-142-3p had strong regulatory effects on actin cytoskeleton as shown by the actin staining in CD4+ T cells. The results suggest that the expression of miR-142-3p is down-regulated in CD4+ T cells from patients with ASO. The down-regulation of miR-142-3p could increase the migration of CD4+ T cells to the vascular walls by regulation of actin cytoskeleton via its target genes, RAC1 and ROCK2.

The in vivo blood compatibility of bio-inspired small diameter vascular graft: effect of submicron longitudinally aligned topography.

BackgroundCardiovascular disease is the leading cause of deaths worldwide and the arterial reconstructive surgery remains the treatment of choice. Although large diameter vascular grafts have been widely used in clinical practices, there is an urgent need to develop a small diameter vascular graft with enhanced blood compatibility. Herein, we fabricated a small diameter vascular graft with submicron longitudinally aligned topography, which mimicked the tunica intima of the native arterial vessels and were tested in Sprague–Dawley (SD) rats.MethodsVascular grafts with aligned and smooth topography were prepared by electrospinning and were connected to the abdominal aorta of the SD rats to evaluate their blood compatibility. Graft patency and platelet adhesion were evaluated by color Doppler ultrasound and immunofluorescence respectively.ResultsWe observed a significant higher patency rate (p = 0.021) and less thrombus formation in vascular graft with aligned topography than vascular graft with smooth topography. However, no significant difference between the adhesion rates on both vascular grafts (smooth/aligned: 0.35‰/0.12‰, p > 0.05) was observed. Moreover, both vascular grafts had few adherent activated platelets on the luminal surface.ConclusionBionic vascular graft showed enhanced blood compatibility due to the effect of surface topography. Therefore, it has considerable potential for using in clinical application.

Scab-Inspired Cytophilic Membrane of Anisotropic Nanofibers for Rapid Wound Healing

This work investigates the influence of cytophilic and anisotropic nanomaterials on accelerated cell attachment and directional migration toward rapid wound healing. Inspired by the anisotropic protein nanofibers in scab, a polyurethane (PU) nanofibrous membrane with an aligned structure was fabricated. The membrane showed good affinity for wound-healing-related cells and could guide cell migration in the direction of PU nanofibers. Also, the morphology and distribution of F-actin and paxillin of attached cells were influenced by the underlying nanofibers. The randomly distributed PU nanofibers and planar PU membrane did not show a distinct impact on cell migration. This scab-inspired cytophilic membrane is promising in applications as functional interfacial biomaterials for rapid wound healing, bone repair, and construction of neural networks.

Co-Targeting IGF-1R and Autophagy Enhances the Effects of Cell Growth Suppression and Apoptosis Induced by the IGF-1R Inhibitor NVP-AEW541 in Triple-Negative Breast Cancer Cells.

Background Triple-negative breast cancer (TNBC) is the most intractable type of breast cancer, and there is a lack of effective targeted therapy. Insulin-like growth factor-1 receptor (IGF-1R) is reportedly a potential target for TNBC treatment. However, satisfying treatment outcomes in breast cancer patients have yet to be achieved with IGF-1R-targeted agents. Methods To confirm whether inhibiting IGF-1R could induce autophagy, we detected autophagy-related proteins by western blotting and immunofluorescence staining of LC3-II. The IGF-1R inhibitor NVP-AEW541, autophagy inhibitor 3-methyladenine (3-MA) and Atg7 small interfering RNA (siRNA) were used to further investigate the effects of autophagy induced by IGF-1R inhibition in TNBC cells. The CCK8 assay, EdU assay, apoptosis and cell cycle analyses were applied to test cell function after treatment. Results NVP-AEW541 markedly induced autophagy in TNBC cells by increasing the levels of the autophagy-related protein Beclin-1 and the LC3-II/LC-I ratio and reducing the selective autophagy substrate p62. Joint application of 3-MA or Atg7 siRNA enhanced the cell growth inhibition and apoptosis effects of NVP-AEW541 by arresting cells at G1/G0 phase and increasing Bax expression and decreasing that of Bcl-2. Conclusion Targeting IGF-1R in TNBC induces cell-protective autophagy, thereby weakening the therapeutic effect of agents directed toward IGF-1R. Our findings reveal that combined use autophagy-disrupting agents can enhance the therapeutic efficacy of IGF-1R inhibitors in TNBC cells and may provide a valuable treatment strategy for IGF-1R inhibitor-based therapies for TNBC and other IGF-1 signaling-associated tumors.

IP-10/CXCR3 Axis Promotes the Proliferation of Vascular Smooth Muscle Cells through ERK1/2/CREB Signaling Pathway

Excessive proliferation of vascular smooth muscle cells is one of the main pathological processes leading to atherosclerosis and intimal hyperplasia after vascular interventional therapy. Our previous study has shown that interferon-γ inducible protein-10 contributes to the proliferation of vascular smooth muscle cell. However, the underlying mechanisms remain unclear. Extracellular signal-regulated kinase 1/2, serine/threonine kinase Akt, and cAMP response element binding protein are signaling pathways, which are considered to play important roles in the processes of vascular smooth muscle cell proliferation. Moreover, chemokine receptor 3 and Toll-like receptor 4 are potential receptors of inducible protein-10 in this process. In the present study, IP-10 was found to directly induce vascular smooth muscle cell proliferation, and exposure to inducible protein-10 activated extracellular signal-regulated kinase 1/2, serine/threonine kinase, and cAMP response element binding protein signaling. Inhibitor of extracellular signal-regulated kinase 1/2, rather than inhibitor of serine/threonine kinase, inhibited the phosphorylation of cAMP response element binding protein and reduced inducible protein-10-stimulated vascular smooth muscle cell proliferation. Knockdown of cAMP response element binding protein by siRNA inhibited inducible protein-10-induced vascular smooth muscle cell proliferation. Moreover, anti-CXCR3 IgG, instead of anti-Toll-like receptor 4 IgG, reduced inducible protein-10-induced vascular smooth muscle cell proliferation and inducible protein-10-stimulated extracellular signal-regulated kinase 1/2 and cAMP response element binding protein activation. Together, these results indicate that inducible protein-10 promotes vascular smooth muscle cell proliferation via chemokine receptor 3 and activation of extracellular signal-regulated kinase 1/2 inducible protein-10-induced vascular smooth muscle cell proliferation. These data provide important targets for future studies to modulate atherosclerosis and restenosis after vascular interventional therapy.

A Human Long Non-Coding RNA ALT1 Controls the Cell Cycle of Vascular Endothelial Cells Via ACE2 and Cyclin D1 Pathway

Background/Aims: ALT1 is a novel long non-coding RNA derived from the alternatively spliced transcript of the deleted in lymphocytic leukemia 2 (DLEU2). To date, ALT1 biological roles in human vascular endothelial cells have not been reported. Methods: ALT1 was knocked down by siRNAs. Cell proliferation was analyzed by cck-8. The existence and sequence of human ALT1 were identified by 3’ rapid amplification of cDNA ends. The interaction between lncRNA and proteins was analyzed by RNA-Protein pull down assay, RNA immunoprecipitation, and mass spectrometry analysis. Results: ALT1 was expressed in human umbilical vein endothelial cells (HUVECs). The expression of ALT1 was significantly downregulated in contact-inhibited HUVECs and in hypoxia-induced, growth-arrested HUVECs. Knocking down of ALT1 inhibited the proliferation of HUVECs by G0/G1 cell cycle arrest. We observed that angiotensin converting enzyme Ⅱ(ACE2) was a direct target gene of ALT1. Knocking-down of ALT1 or its target gene ACE2 could efficiently decrease the expression of cyclin D1 via the enhanced ubiquitination and degradation, in which HIF-1α and protein von Hippel-Lindau (pVHL) might be involved. Conclusion: The results suggested the human long non-coding RNA ALT1 is a novel regulator for cell cycle of HUVECs via ACE2 and cyclin D1 pathway.

Denervation in Femoral Artery-Ligated Hindlimbs Diminishes Ischemic Recovery Primarily via Impaired Arteriogenesis

Aims Multiple factors regulate arteriogenesis. Peripheral nerves play a crucial role in vascular remodeling, but the function of peripheral nerves during arteriogenesis is obscure. Our study investigated the contribution of denervation to arteriogenesis during post-ischemic recovery from hindlimb femoral artery ligation. Methods and Results Sprague-Dawley rats were randomly allocated into four groups of normal control (NC), hindlimb ischemia (HI), hindlimb ischemia with denervation (HID) and hindlimb simple denervation (HD). Hindlimb ischemic recovery was assessed by clinical assessment and tibialis anterior muscle remodeling on day 28 post-surgery. Blood flow was determined by laser Doppler imaging on day 0, 3, 7, 14 and 28 post-surgery. Collateral number of hindlimb was observed by angiography and gracilis muscles were tested by immunostaining on day 7 and 28 post-surgery. Angiogenesis was accessed by counting CD31 positive capillaries in tibialis anterior muscles on day 28 post-surgery. Group HID showed impaired ischemic recovery compared with the other 3 groups and impaired blood flow recovery compared with group HI on day 28 post-surgery. The collateral number and capillary density of group HID were lower than group HI. The collateral diameter of both group HID and group HI significantly increased compared with group NC. However, the lumen diameter was much narrower and the vessel wall was much thicker in group HID than group HI. We also demonstrated that the thickened neointima of collaterals in group HID comprised of smooth muscle cells and endothelial cells. Conclusions Denervation of the ligated femoral artery in the hindlimb impairs ischemic recovery via impaired perfusion. The possible mechanisms of impaired perfusion are lower collateral number, lower capillary density and most likely narrower lumen, which damage ischemic recovery. This study illustrates the crucial role of peripheral nerves in arteriogenesis using a model combined ischemia with denervation in hindlimb.