Femoral Artery Injury Research Articles

Mechanism of matrix metalloproteinase axis-induced neointimal growth

Tumor necrosis factor-α, platelet-derived growth factor, matrix metalloproteinases 9 and 2 have very important roles in neointimal hyperplasia, which develops after endovascular injury. However, the relationships among the four factors in inducing neointimal hyperplasia are unclear. Here, we used a mouse model of femoral arterial transluminal wire injury, and examined neointimal hyperplasia within the 28days that followed the injury. We confirmed that the neointima kept growing during the 28days, and found that expression of TNF-α and PDGF mRNAs in femoral arteries peaked within 24h after injury. However, MMP9 mRNA expression peaked 7days, and MMP2 mRNA expression peaked 28days after injury. Then, we administered exogenous TNF-α or PDGF to the peri-femoral artery following an injury, and found that exogenous TNF-α led to significantly more neointimal hyperplasia during the first 2weeks, and PDGF led to increased neointimal hyperplasia during the second 2weeks after injury. We also used the model of femoral artery injury in MMP9- or MMP2-deficient (MMP9−/− or MMP2−/−) mice. We found that neointimal hyperplasia was reduced in MMP9−/− mice during the first 2weeks after injury, and neointimal hyperplasia was reduced in MMP2−/− mice during the second 2weeks after injury. When TNF-α or PDGF was administered to the peri-femoral artery immediately after injury, TNF-α did not promote neointimal hyperplasia in MMP9−/− mice during the first 2weeks after injury but did in MMP2−/− mice, and PDGF did not promote neointimal hyperplasia in MMP2−/− mice during the second 2weeks after injury but did in MMP9−/− mice. We used an in vitro system to treat vascular smooth muscle cells (VSMCs) with TNF-α or PDGF; TNF-α induced MMP9, but not MMP2, expression at a fast reaction speed, while PDGF induced MMP2, but not MMP9, expression at a slow reaction speed. Meanwhile, TNF-α induced VSMC migration in a MMP9-dependent manner, and PDGF induced VSMC proliferation in a MMP2-dependent manner. Taken together, our studies elucidated the axis of TNF-α-MMP9-VSMC migration and PDGF-MMP2-VSMC proliferation, both of which contributed to the mechanism of neointimal hyperplasia formation.

Abstract 18000: The Role of X-box Binding Protein 1 Splicing in Smooth Muscle Cell Proliferation and Neointima Formation

Background: Smooth muscle cell (SMC) proliferation plays an important role in neointima formation in response to vascular injury. However, the underlying mechanism is still not well understood. It has been well documented that endoplasmic reticulum (ER) stress plays a provoking role in cardiovascular disease including neointima formation. As one of the key transducer in ER stress response, the X-box binding protein 1 (XBP1) has been demonstrated to contribute to endothelial cell proliferation, autophagic response and apoptosis, but less is known about its role in SMC growth. Methods and Results: In this study, we intend to study the role of XBP1 in SMC proliferation and its contribution to neointima formation in response to vascular injury. Quantitative RT-PCR and immunohistological staining analysis revealed that XBP1 splicing was up-regulated in the arterial vasculature in aged ApoE deficient mice and in response to vascular injury in wild type mice with elevated XBP1 protein in the neointima. Platelet derived growth factor (PDGF) induced XBP1 splicing via the interaction between PDGF receptor and inositol requiring enzyme 1 alpha (IRE1α). Transient over-expression of the spliced XBP1 (XBP1s) increased SMC proliferation, while knockdown of XBP1 or IRE1α abolished PDGF-induced SMC proliferation. XBP1s down-regulated calponin H1 gene expression at mRNA and protein levels, which might be through the down-regulation of TGFβ3 signalling. Reconstitution of calponin H1 via adenoviral transfer could ablate XBP1s-induced SMC proliferation. Addition of exogenous TGFβ3 abolished XBP1s-induced calponin H1 suppression and SMC proliferation. High levels of TGFβ3 and calponin H1 were detected in SMCs isolated from SM22-Cre/XBP1 loxP mice. These SMCs showed retardation in proliferation as compared to SMCs from wild type litters. Importantly, in the femoral artery injury model, XBP1 deficiency in SMCs prevented the neointima formation. CONCLUSION: XBP1 splicing plays an important role in SMC proliferation via regulating calponin H1 expression. Targeting XBP1 splicing in SMC may provide a novel therapeutic strategy to intervene neointima formation.

Apurinic/apyrimidinic endonucelase 1 maintains adhesion of endothelial progenitor cells and reduces neointima formation

Apurinic/apyrimidinic endonuclease 1 (APE1) is a multifunctional protein that processes DNA-repair function and controls cellular response to oxidative stress. Endothelial progenitor cells (EPCs) are recruited to oxidative stress-rich injured vascular walls and positively contribute to vascular repair and endothelialization. We hypothesized that APE1 functions for EPCs-mediated inhibition of neointima formation in injured vasculature. EPCs isolated from bone marrow cells of C57BL6 mice (12-16 wk old) were able to survive in the presence of hydrogen peroxide (H2O2; up to 1,000 μM) due to the highly expressed reactive oxygen species (ROS) scavengers. However, adhesion capacity of EPCs was significantly inhibited by H2O2 (100 μM) even though an intracellular ROS was retained at small level. An APE1-selective inhibitor or RNA interference-mediated knockdown of endogenous APE1 in EPCs aggravated the H2O2-mediated inhibition of EPCs-adhesion. In contrast, when APE1 was overexpressed in EPCs using an adenovirus harboring the APE1 gene (APE-EPCs), adhesion was significantly improved during oxidative stress. To examine in vivo effects of APE1 in EPCs, APE-EPCs were transplanted via the tail vein after wire-mediated injury of the mouse femoral artery. The number of adherent EPCs at injured vascular walls and the vascular repair effect of EPCs were enhanced in APE-EPCs compared with control EPCs. Among the cellular functions of EPCs, adhesion is especially sensitive to oxidative stress. APE1 enhances in vivo vascular repair effects of EPCs in part through the maintenance of adhesion properties of EPCs. APE1 may be a novel and useful target gene for effective cellular transplantation therapy.

Tuning Ligand Density on Intravenous Hemostatic Nanoparticles Dramatically Increases Survival Following Blunt Trauma

Targeted nanoparticles are being pursued for a range of medical applications. Here we utilized targeted nanoparticles (synthetic platelets) to halt bleeding in acute trauma. One of the major questions that arises in the field is the role of surface ligand density in targeted nanoparticles' performance. We developed intravenous hemostatic nanoparticles (GRGDS-NP1) and previously demonstrated their ability to reduce bleeding following femoral artery injury and increase survival after lethal liver trauma in the rat. These nanoparticles are made from block copolymers, poly(lactic-co-glycolic acid)-b-poly L-lysine-b-poly(ethylene glycol). Surface-conjugated targeting ligand density can be tightly controlled with this system, and here we investigated the effect of varying density on hemostasis and biodistribution. We increased the targeting peptide (GRGDS) concentration 100-fold (GRGDS-NP100) and undertook an in vitro dose-response study using rotational thromboelastometry, finding that GRGDS-NP100 hemostatic nanoparticles were efficacious at doses at least 10 times lower than the GRGDS-NP1. These results were recapitulated in vivo, demonstrating efficacy at eight-fold lower concentration after lethal liver trauma. 1 h survival increased to 92% compared with a scrambled peptide control, 45% (OR = 14.4, 95% CI = [1.36, 143]), a saline control, 47% (OR = 13.5, 95% CI = [1.42, 125]), and GRGDS-NP1, 80% (OR = 1.30, n.s.). This work demonstrates the impact of changing synthetic platelet ligand density on hemostasis and lays the foundation for methods to determine optimal ligand concentration parameters.

Management of war-related vascular injuries: experience from the second gulf war

AimTo study the biomechanism, pattern of injury, management, and outcome of major vascular injuries treated at Mubarak Al-Kabeer Teaching Hospital, Kuwait during the Second Gulf War.MethodsThis is a descriptive retrospective study. War-related injured patients who had major vascular injuries and were treated at Mubarak Al-Kabeer Teaching Hospital from August 1990 to September 1991 were studied. Studied variables included age, gender, anatomical site of vascular injury, mechanism of injury, associated injuries, type of vascular repair, and clinical outcome.Results36 patients having a mean (SD) age of 29.8 (10.2) years were studied. 32 (89%) were males and 21 (58%) were civilians. Majority of injuries were caused by bullets (47.2%) and blast injuries (47.2%). Eight patients (22%) presented with shock.There were 31 arterial injuries, common and superficial femoral artery injuries were most common (10/31). Arterial repair included interposition saphenous vein graft in seven patients, thrombectomy with end-to-end / lateral repair in twelve patients, vein patch in two patients, and arterial ligation in four patients. Six patients had arterial ligation as part of primary amputation. 3/21 (14.3%) patients had secondary amputation after attempted arterial vascular repair of an extremity. There were a total of 17 venous injuries, 13 managed by lateral suture repair and 4 by ligation. The median (range) hospital stay was 8 (1–76) days. 5 patients died (14%).ConclusionsMajor vascular injuries occurred in 10% of hospitalized war-related injured patients. Our secondary amputation rate of extremities was 14%. The presence of a vascular surgeon within a military surgical team is highly recommended. Basic principles and techniques of vascular repair remain an essential part of training general surgeons because it may be needed in unexpected wars.

Role of macrophage-derived hypoxia-inducible factor (HIF)-1α as a mediator of vascular remodelling

Excessive vascular remodelling leads to progression of a wide range of vasculopathies, and the immune response to intimal injuries is crucial in this process. This vascular remodelling occurs in the hypoxic microenvironment and is closely related to the immune system. Macrophages play a key role in immunological-cell-mediated arterial remodelling. In this study, we clarified the role of macrophage-derived hypoxia-inducible factor (HIF-1α) in vascular remodelling. Wire-induced femoral arterial injury was inflicted in mice lacking the macrophage-specific HIF-1α gene and in their wild-type counterparts. The mutant mice showed both suppressed wire-induced neointimal thickening and decreased infiltration of inflammatory cells in the adventitia, compared with wild-type mice. Studies to clarify the mechanism of restrained vascular remodelling in the mutant mice revealed decreased production of pro-inflammatory cytokines by the activated macrophages and suppressed macrophage migration activity in the mutant mice. Gene expressions of the HIF-1α-deficient macrophages positively correlated with the phenotypic profile of M2 macrophages and negatively correlated with that of M1 macrophages. Our results show that HIF-1α in macrophages plays a crucial role in promoting vascular inflammation and remodelling. As decreasing HIF-1α activity in macrophages may prevent the progression of vascular remodelling, HIF-1α may be a possible therapeutic target in vascular diseases.

Differential Endothelial Coverage, Response to Injury and Neointimal Integration of CX3CR1/Smooth Muscle-Like Cells after Carotid or Femoral Arterial Injury

Background: Previously, we established the importance of the CX3CL1/CX3CR1 axis in the promotion of myeloid cell differentiation into neointimal smooth muscle-like cells (SMLC). Methods: In this study, acute (24 h) endothelial coverage and CX3CL1 expression as well as chronic (2 weeks) vascular remodeling was examined with respect to whether myeloid CX3CR1⁺ SMLC number in the neointima differed between carotid and femoral artery wire injury. Results and Conclusion: Twenty-four hours after injury, CX3CL1 expression was significantly elevated in injured carotid compared to femoral arteries. In mice with CX3CR1 promoter-driven expression of green fluorescent protein, neointima formation was significantly greater (p < 0.05) 2 weeks after injury in femoral versus carotid arteries as determined by the intima/media ratio. Although the percentage of F4/80/CX3CR1⁺ cell integration was similar in both models, the carotid lesion had greater proportions of cells coexpressing CX3CR1 and both α-smooth muscle actin and calponin (p < 0.05). Wire injury of carotid arteries was associated with greater CX3CL1 expression in the acute phase followed by greater CX3CR1 coexpressing SMLC content in later lesions as well as less neointima formation than in femoral arteries. This may, in part, explain the variability in lesion composition after carotid versus femoral wire injury.

Type VIII Collagen Mediates Vessel Wall Remodeling after Arterial Injury and Fibrous Cap Formation in Atherosclerosis

Collagens in the atherosclerotic plaque signal regulation of cell behavior and provide tensile strength to the fibrous cap. Type VIII collagen, a short-chain collagen, is up-regulated in atherosclerosis; however, little is known about its functions invivo. We studied the response to arterial injury and the development of atherosclerosis in type VIII collagen knockout mice (Col8(-/-) mice). After wire injury of the femoral artery, Col8(-/-) mice had decreased vessel wall thickening and outward remodeling when compared with Col8(+/+) mice. We discovered that apolipoprotein E (ApoE) is an endogenous repressor of the Col8a1 chain, and, therefore, in ApoE knockout mice, type VIII collagen was up-regulated. Deficiency of type VIII collagen in ApoE(-/-) mice (Col8(-/-);ApoE(-/-)) resulted in development of plaques with thin fibrous caps because of decreased smooth muscle cell migration and proliferation and reduced accumulation of fibrillar type I collagen. In contrast, macrophage accumulation was not affected, and the plaques had large lipid-rich necrotic cores. We conclude that in atherosclerosis, type VIII collagen is up-regulated in the absence of ApoE and functions to increase smooth muscle cell proliferation and migration. This is an important mechanism for formation of a thick fibrous cap to protect the atherosclerotic plaque from rupture.

Omega 3 polyunsaturated fatty acids modulate cyclooxygenase‐2 induction via interactions with GPR120

Cyclooxygenase‐2 (COX‐2)‐derived prostaglandins are implicated in numerous inflammatory disorders. Omega 3 polyunsaturated fatty acids (ω3 PUFAs) such as docosahexaenoic acid (DHA) are recognized as anti‐inflammatory agents. Here, we explore the potential interaction between COX‐2 induction and ω3 PUFAs via the G‐protein‐coupled receptor 120 (GPR120). Pre‐exposure to DHA for 24 h reduced prostaglandin E2 (PGE2) production primarily through COX‐2 inhibition and partially through down‐regulating microsomal prostaglandin E synthase‐1 (mPGES‐1) expression, but not through affecting COX‐1 expression. DHA could also inhibit activation of a human COX‐2 promoter‐luciferase reporter construct containing NF‐κB response elements. We also demonstrated that COX‐2 induction is attenuated in macrophages obtained from Fat‐1 mice where ω3 PUFAs are synthesized endogenously from ω6 PUFAs. In a FeCl3 femoral artery injury mouse model, post‐injury blood flow in Fat‐1 mice was higher relative to their wild type littermates. Knockdown of GPR120 abrogates DHA effects on COX‐2 induction, PGE2 production and interleukin 6 (IL‐6) gene expression, through ERK, Akt, and JNK signaling pathways. These studies provide a new mechanistic basis for the anti‐inflammatory effects of PUFAs via interactions with GPR120. Supported by a joint grant from the CIHR and NSFC (CCI 117951).

Accelerated reendothelialization, increased neovascularization and erythrocyte extravasation after arterial injury in BAMBI-/- mice.

BackgroundIntimal injury rapidly activates TGFβ and enhances vascular repair by the growth of endothelial (EC) and vascular smooth muscle cells (VSMC). The response to the TGFβ family of growth factors can be modified by BAMBI (BMP, Activin, Membrane Bound Inhibitor) acting as a non-signaling, competitive antagonist of TGFβ type I receptors such as ALK 1 and 5. In vivo the effect of BAMBI will depend on its cell-specific expression and of that of the ALK type receptors. We recently reported EC restricted BAMBI expression and genetic elimination of BAMBI resulting in an in vitro and in vivo phenotype characterized by endothelial activation and proliferation involving alternative pathway activation by TGFβ through ALK 1.Methodology/Principal FindingsTo test the hypothesis that BAMBI modulates arterial response to injury via its effects on endothelial repair and arterial wall neovascularization we used a model of femoral arterial denudation injury in wild type (WT) and BAMBI−/− mice. Arterial response was evaluated at 2 and 4 weeks after luminal endothelial denudation of femoral arteries. The BAMBI−/− genotype mice showed accelerated luminal endothelial repair at 2 weeks and a highly unusual increase in arterial wall neovascularization compared to WT mice. The exuberant intimal and medial neovessel formation with BAMBI−/− genotype was also associated with significant red blood cell extravasation. The bleeding into the neointima at 2 weeks transiently increased it’s area in the BAMBI−/−genotype despite the faster luminal endothelial repair in this group. Vascular smooth muscle cells were decreased at 2 weeks in BAMBI−/− mice, but comparable to wild type at 4 weeks.Conclusions/SignificanceThe absence of BAMBI results in a highly unusual surge in arterial wall neovascularization that surprisingly mimiks features of intra-plaque hemorrhage of advanced atheroma in a mechanical injury model. This suggests important effects of BAMBI on arterial EC homeostasis that need to be further studied in a model of inflammatory atherosclerosis.

Inactivation of Nuclear Factor-Y Inhibits Vascular Smooth Muscle Cell Proliferation and Neointima Formation

Atherosclerosis and restenosis are multifactorial diseases associated with abnormal vascular smooth muscle cell (VSMC) proliferation. Nuclear factor-Y (NF-Y) plays a major role in transcriptional activation of the CYCLIN B1 gene (CCNB1), a key positive regulator of cell proliferation and neointimal thickening. Here, we investigated the role of NF-Y in occlusive vascular disease. We performed molecular and expression studies in cultured cells, animal models, and human tissues. We find upregulation of NF-Y and cyclin B1 expression in proliferative regions of murine atherosclerotic plaques and mechanically induced lesions, which correlates with higher binding of NF-Y to target sequences in the CCNB1 promoter. NF-YA expression in neointimal lesions is detected in VSMCs, macrophages, and endothelial cells. Platelet-derived growth factor-BB, a main inductor of VSMC growth and neointima development, induces the recruitment of NF-Y to the CCNB1 promoter and augments both CCNB1 mRNA expression and cell proliferation through extracellular signal-regulated kinase 1/2 and Akt activation in rat and human VSMCs. Moreover, adenovirus-mediated overexpression of a NF-YA-dominant negative mutant inhibits platelet-derived growth factor-BB-induced CCNB1 expression and VSMC proliferation in vitro and neointimal lesion formation in a mouse model of femoral artery injury. We also detect NF-Y expression and DNA-binding activity in human neointimal lesions. Our results identify NF-Y as a key downstream effector of the platelet-derived growth factor-BB-dependent mitogenic pathway that is activated in experimental and human vasculoproliferative diseases. They also identify NF-Y inhibition as a novel and attractive strategy for the local treatment of neointimal formation induced by vessel denudation.

Very bad clinical aspect towards diagnosis of deep femoral artery injury: Hypovolemic shock

Very bad clinical aspect towards diagnosis of deep femoral artery injury: Hypovolemic shock

Myeloid Cell 5-Lipoxygenase Activating Protein Modulates the Response to Vascular Injury

Human genetics have implicated the 5-lipoxygenase enzyme in the pathogenesis of cardiovascular disease, and an inhibitor of the 5-lipoxygenase activating protein (FLAP) is in clinical development for asthma. Here we determined whether FLAP deletion modifies the response to vascular injury. Vascular remodeling was characterized 4 weeks after femoral arterial injury in FLAP knockout mice and wild-type controls. Both neointimal hyperplasia and the intima/media ratio of the injured artery were significantly reduced in the FLAP knockouts, whereas endothelial integrity was preserved. Lesional myeloid cells were depleted and vascular smooth muscle cell (VSMC) proliferation, as reflected by bromodeoxyuridine incorporation, was markedly attenuated by FLAP deletion. Inflammatory cytokine release from FLAP knockout macrophages was depressed, and their restricted ability to induce VSMC migration ex vivo was rescued with leukotriene B(4). FLAP deletion restrained injury and attenuated upregulation of the extracellular matrix protein, tenascin C, which affords a scaffold for VSMC migration. Correspondingly, the phenotypic modulation of VSMC to a more synthetic phenotype, reflected by morphological change, loss of α-smooth muscle cell actin, and upregulation of vascular cell adhesion molecule-1 was also suppressed in FLAP knockout mice. Transplantation of FLAP-replete myeloid cells rescued the proliferative response to vascular injury. Expression of lesional FLAP in myeloid cells promotes leukotriene B(4)-dependent VSMC phenotypic modulation, intimal migration, and proliferation.

Intravenous Hemostatic Nanoparticles Increase Survival Following Blunt Trauma Injury

Trauma is the leading cause of death for people ages 1-44, with blood loss comprising 60-70% of mortality in the absence of lethal CNS or cardiac injury. Immediate intervention is critical to improving chances of survival. While there are several products to control bleeding for external and compressible wounds, including pressure dressings, tourniquets, or topical materials (e.g., QuikClot, HemCon), there are no products that can be administered in the field for internal bleeding. There is a tremendous unmet need for a hemostatic agent to address internal bleeding in the field. We have developed hemostatic nanoparticles (GRGDS-NPs) that reduce bleeding times by ~50% in a rat femoral artery injury model. Here, we investigated their impact on survival following administration in a lethal liver resection injury in rats. Administration of these hemostatic nanoparticles reduced blood loss following the liver injury and dramatically and significantly increased 1 h survival from 40 and 47% in controls (inactive nanoparticles and saline, respectively) to 80%. Furthermore, we saw no complications following administration of these nanoparticles. We further characterized the nanoparticles' effect on clotting time (CT) and maximum clot firmness (MCF) using rotational thromboelastometry (ROTEM), a clinical measurement of whole-blood coagulation. Clotting time is significantly reduced, with no change in MCF. Administration of these hemostatic nanoparticles after massive trauma may help staunch bleeding and improve survival in the critical window following injury, and this could fundamentally change trauma care.

The efficacy of Combat Gauze in extreme physiologic conditions

IntroductionCombat Gauze (CG) is currently the most widely used hemostatic dressing in combat. The testing of CG was initially performed in healthy and physiologically normal animals. The goal this study was to assess the efficacy in a model of severe acidosis and coagulopathy. MethodsTo obtain an acidotic and coagulopathic model, Yorkshire swine sustained 35% blood volume hemorrhage followed by a 50-min supraceliac aortic ischemia-reperfusion injury with 6-h resuscitation (epinephrine to keep mean arterial pressure >40 and intravenous fluids to keep central venous pressure >4). We created a femoral artery injury and randomized the animals to CG versus a standard gauze (SG) dressing. We performed rotational thromboelastography with both CG and SG. ResultsUsing our model, 17 anesthetized Yorkshire swine developed appropriately significant coagulopathy, acidosis, and anemia. The SG failure rate was 100% on the first application and worked once on the second application. Combat Gauze was successful in achieving hemostasis 93% of the time on the first application and had 100% success with the second application. Rotational thromboelastography demonstrated that the only difference was a decreased clotting time with CG compared with SG (P = 0.012). ConclusionsCombat Gauze significantly outperforms standard gauze dressings in a model of major vascular hemorrhage in acidotic and coagulopathic conditions. This effect appears to result from a decreased time lag between activation and first detectable clotting. Combat Gauze appears to maintain its efficacy even in the setting of severe acidosis and coagulopathy for the control of hemorrhage from vascular injury.

Hemostatic function of novel absorbable crosslinked microporous hemostatic starch

Objective To prepare an absorbable crosslinked microporous hemostatic starch(ACMHS),to observe its hemostasis effect in the liver,kidney and femoral artery,and to discuss the hemostasis mechanism.Methods Thirty adult healthy New Zealand rabbits of either sex,weighing 2,000-2,250 g,were equally randomized into 3 groups: liver bleeding group(group A),kidney bleeding group(group B) and femoral artery bleeding group(group C).Each group was further divided into a test group and a control group randomly(n=5) according to different hemostatic powders;ACMHS was used in the test group(group A1,B1,C1),and AristaTM was used in the control group(group A2,B2,C2).The bleeding amount and bleeding time were accurately recorded.The pathological changes at incision and in the surrounding tissues of the liver,kidney and femoral artery were observed by hematoxylin-eosin staining after test.Results All the bleeding amounts of group A1 and A2 were(1.02±0.10) g and(1.03±0.09) g,and the bleeding time periods of group A1 and A2 were(92.6±5.16) s and(95.6±5.31) s,respectively(P0.05).All the bleeding amounts of group B1 and B2 were(0.92±0.09) g and(0.94±0.08) g,and the bleeding time periods of group B1 and B2 were(87.5±7.48) s and(88.8±6.54) s,respectively(P0.05).All the hemostatic efforts failed in group C.Hematoxylin-eosin staining showed accumulation of red blood cells at the incision and in surrounding tissues of the liver and kidney in group A and group B,without evidence of burn.Conclusion ACMHS has the same hemostatic function as AristaTM in parenchymatous organ injury,but it is not suitable for bleeding of femoral artery injury with high pressure.

Surface Markers of Heterogeneous Peripheral Blood–Derived Smooth Muscle Progenitor Cells

Smooth muscle progenitor cells (SMPCs) were intriguingly shown to act as a double-edged sword in the pathogenesis of atherosclerosis. To fully clarify the roles of SMPCs in atherosclerosis, a distinct panel of SMPC surface markers is mandatory to be developed. Microarray gene expression analyses were used to discover potential surface markers of SMPCs. In vitro and in vivo experiments documented that platelet-derived growth factor receptor-β, carboxypeptidase M, carbonic anhydrase 12, receptor activity-modifying protein 1, and low-density lipoprotein receptor-related protein were the 5 specific surface markers regulating various SMPC functions, including migration, extracellular matrix formation, resistance to hypoxia, and anti-inflammation. In severe combined immunodeficiency/nonobese diabetic mice after femoral arterial wire injury, injected human peripheral blood mononuclear cells contributed to substantial amount of neointimal α-smooth muscle actin-positive cells, coexpressing platelet-derived growth factor receptor-β, carboxypeptidase M, carbonic anhydrase 12, receptor activity-modifying protein 1, and low-density lipoprotein receptor-related protein. Based on these markers, a novel quantification assay was developed to enumerate circulating early SMPC. Early SMPC numbers were higher in patients with unstable angina compared with those with normal coronary angiograms. In patients with acute ST-elevation myocardial infarction, different patterns of serial early SMPC changes were noted, related to different clinical presentations. Surface markers of heterogeneous SMPCs exhibit various functions associated with atherosclerotic pathophysiology. Quantification of surface marker-defined SMPCs provides a platform for studying SMPCs in cardiovascular diseases.

Efficacy and safety of emergency non-invasive pelvic ring stabilisation

BackgroundUrgent non-invasive pelvic ring stabilisation (pelvic binding, PB) in shocked patients is recommended by state and institutional guidelines regardless of the fracture pattern. The purpose of this study was to determine the adherence to the guidelines, efficacy of the technique and identification of potential adverse effects associated with PB. Patients and methodsA 41-month retrospective analysis of the prospective pelvic fracture database was undertaken at a level 1 trauma centre. High-energy pelvic fractures were included in the analysis with exclusion of the A type injuries (AO/OTA classification) and patients who were dead on arrival. Collected data included patient demographics, injury severity score, fracture classification, application and timing of PB, associated injuries, physiological parameters, resuscitation fluids and outcomes. Pre and post-PB radiographs were reviewed. The potential effects of the PB on soft tissue (femoral vessel, bladder and rectal injury) complications were assessed by independent experts. Results115 patients with high-energy B and C type pelvic ring injuries were included. Thirty-six (31%) patients presented in haemorrhagic shock on arrival. A total of 43 pelvic bindings were performed, 18 of them on shocked patients. The adherence to the guidelines was 50% (18/36) overall. Analysing fracture types of shocked patients the adherence was: B1 80%, B2 20%, B3 20%, C1 66%, C2 86%, C3 33%. The alignment of the pelvis was improved or perfect on post-PB radiographs in 68% and had not changed in 21%. In some cases of B2 and B3 type injuries the PB increased the deformity after application (11%). There were 10 deaths (8.7%) in the study group, with 4 deaths attributed to acute pelvic bleeding. Two of these had PB applied and two were identified as potential for improvement. One femoral artery injury, four bladder injuries and three rectum injuries were identified in patients who had PB applied. Association between the PB and these injuries is unlikely. ConclusionThe adherence to the guidelines should be improved with further education and system development. The good effect of the technique was evident on radiographs. Although in some lateral compression fracture patterns the deformity increased, no hazards were associated with the use of PB.

Gαq G proteins modulate MMP-9 gelatinase during remodeling of the murine femoral artery

BackgroundVessels heal after injury and G protein–coupled receptors are involved in the vascular smooth muscle cell proliferation required to form intimal hyperplasia. We have previously identified the role of Gαq in vascular smooth muscle cell proliferation in vitro. This study now examines the role of Gαq in the developing intimal hyperplasia in a murine model and the impact of disruption of Gαq signaling on intimal hyperplasia development. MethodsWe employed a murine femoral wire injury model in which a micro-wire is passed through a branch of the femoral artery and used to denude the common femoral artery. We perfusion-fixed specimens and stained sections with hematoxylin-eosin and Movat's stains such that morphometric analysis could be performed using an Image-Pro system. We also harvested additional specimens of femoral artery and snap-froze them for Western blotting or zymography, to allow for the study of G protein expression and both protease expression and activity. We used contralateral vessels as controls. We immersed additional vessels in pluronic gel containing the chemical Gαq G protein inhibitors GP-2A, siRNA to Gαq or adenovirus containing mutant inactive Gαq. ResultsGαq expression increased in a time-dependent manner after femoral artery injury. Sham-operated vessels did not produce such a response. Inhibition of Gαq reduced cell proliferation without affecting cell migration. Interruption of Gαq signaling also inhibited the development of intimal hyperplasia. Inhibition of Gαq did not alter peak urinary-type plasminogen activator activity and expression, but did increase early plasminogen activator inhibitor-1 activity and expression. Inhibition of Gαq reduced peak metalloproteinase (MMP)-9 activity at Day 3 but did not influence peak MMP-2 activity at Day 7. Protein expression for MMP-9 was also decreased, but that of MMP-2 was not affected. There were no changes in the expression or the activity of the respective inhibitors for MMP-9 and MMP-2, and tissue inhibitor of metalloproteinases-1 and -2. ConclusionsThese data demonstrate that femoral wire injury in the mouse is associated with a time-dependent increase in Gαq expression. Inhibition of Gαq alters cell proliferation and is associated with decreased MMP-9 expression and activity.

Abstract 491: Injury-Activated TGFβ Recruits MSCs for Vascular Remodeling

Stem/progenitor cells can be recruited to participate in tissue remodeling, regeneration, or repair following injury. In particular, bone marrow-derived or local resident stem /progenitor cells are implicated in vascular repair and remodeling. It is believed that migratory factor(s) released by injured tissue creates a gradient to mediate the migration of stem cells to the injury sites. The key mediator(s) inducing the recruitment of the cells to the vascular lesions remains to be defined. Here we show that nestin + cells, which represent similar population as Sca1 + CD29 + CD11b - CD45 - mesenchymal/stromal stem cells (MSCs), were recruited and incorporated into the neointimal tissue in both rat model of balloon injury of carotid artery and mouse model of wire injury of femoral artery. Importantly, elevated active TGFβ1 level was observed in the injured vessels as early as 8 hr post injury, and the elevation lasted for 2 wks. To investigate whether injury-induced activation of TGFβ1 in vascular matrix stimulates migration of MSCs, we developed an aorta-conditioned medium (Aorta-CM)-based cell migration assay in which MSCs were placed in the upper chamber and the Aorta-CM prepared by culturing ex vivo injured aorta was placed in the lower chamber of a transwell chamber. Aorta-CM prepared from ex vivo injured aorta significantly enhanced cell migration compare to CM prepared from uninjured aorta. When neutralizing antibody specific for TGFβ1 or the inhibitor of TGFβ type I receptor (TβRI) was added to the CM, the migration of MSCs was almost abolished, indicating that active TGFβ1 released by the injured arteries mediates MSCs migration. To examine the role of TGFβ in MSCs recruitment following vascular injury in vivo , TβRI inhibitor was injected into mice with injury of femoral arteries. Both the development of neointima and the recruitment of nestin + cells were blocked with the inhibitor treatment compare to those with vehicle treatment. Collectively, the results suggest that TGFβ is an injury-activated messenger essential for the recruitment of MSCs to participate in vascular remodeling.