-
Eric W Holroyd,
Sinny Delacroix,
Katarina Larsen,
Adriana Harbuzariu,
Peter J Psaltis,
Ling Wang,
Shuchong Pan,
Thomas A White,
Tyra A Witt, Laurel S Kleppe,
Cheryl S Mueske,
Debabrata Mukhopadhyay,
Robert D Simari
[show abstract]
[hide abstract]
ABSTRACT: Tissue factor pathway inhibitor (TFPI) is the primary regulator of the tissue factor (TF) coagulation pathway. As such, TFPI may regulate the proangiogenic effects of TF. TFPI may also affect angiogenesis independently of TF, through sequences within its polybasic carboxyl terminus (TFPI C terminus [TFPIct]). We aimed to determine the effects of TFPI on angiogenesis and the role of TFPIct.
Transgenic overexpression of TFPI attenuated angiogenesis in the murine hindlimb ischemia model and an aortic sprout assay. In vitro, TFPI inhibited endothelial cell migration. Peptides within the human TFPIct inhibited endothelial cell cord formation and migration in response to vascular endothelial growth factor (VEGF) 165 but not VEGF121. Furthermore, exposure to human TFPIct inhibited the phosphorylation of VEGF receptor 2 at residue Lys951, a residue known to be critical for endothelial cell migration. Finally, systemic delivery of a murine TFPIct peptide inhibited angiogenesis in the hindlimb model.
These data demonstrate an inhibitory role for TFPI in angiogenesis that is, in part, mediated through peptides within its carboxyl terminus. In addition to its known role as a TF antagonist, TFPI, via its carboxyl terminus, may regulate angiogenesis by directly blocking VEGF receptor 2 activation and attenuating the migratory capacity of endothelial cells.
Arteriosclerosis Thrombosis and Vascular Biology 03/2012; 32(3):704-11. · 6.37 Impact Factor
-
Peter J Psaltis,
Adriana Harbuzariu,
Sinny Delacroix,
Tyra A Witt,
Eric W Holroyd,
Daniel B Spoon,
Scott J Hoffman,
Shuchong Pan, Laurel S Kleppe,
Cheryl S Mueske,
Rajiv Gulati,
Gurpreet S Sandhu,
Robert D Simari
[show abstract]
[hide abstract]
ABSTRACT: Hematopoiesis originates from the dorsal aorta during embryogenesis. Although adult blood vessels harbor progenitor populations for endothelial and smooth muscle cells, it is not known if they contain hematopoietic progenitor or stem cells. Here, we hypothesized that the arterial wall is a source of hematopoietic progenitor and stem cells in postnatal life.
Single-cell aortic disaggregates were prepared from adult chow-fed C57BL/6 and apolipoprotein E-null (ApoE(-/-)) mice. In short- and long-term methylcellulose-based culture, aortic cells generated a broad spectrum of multipotent and lineage-specific hematopoietic colony-forming units, with a preponderance of macrophage colony-forming units. This clonogenicity was higher in lesion-free ApoE(-/-) mice and localized primarily to stem cell antigen-1-positive cells in the adventitia. Expression of stem cell antigen-1 in the aorta colocalized with canonical hematopoietic stem cell markers, as well as CD45 and mature leukocyte antigens. Adoptive transfer of labeled aortic cells from green fluorescent protein transgenic donors to irradiated C57BL/6 recipients confirmed the content of rare hematopoietic stem cells (1 per 4 000 000 cells) capable of self-renewal and durable, low-level reconstitution of leukocytes. Moreover, the predominance of long-term macrophage precursors was evident by late recovery of green fluorescent protein-positive colonies from recipient bone marrow and spleen that were exclusively macrophage colony-forming units. Although trafficking from bone marrow was shown to replenish some of the hematopoietic potential of the aorta after irradiation, the majority of macrophage precursors appeared to arise locally, suggesting long-term residence in the vessel wall.
The postnatal murine aorta contains rare multipotent hematopoietic progenitor/stem cells and is selectively enriched with stem cell antigen-1-positive monocyte/macrophage precursors. These populations may represent novel, local vascular sources of inflammatory cells.
Circulation 12/2011; 125(4):592-603. · 14.74 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Pulmonary hypertension (PH) is a commonly recognized complication of chronic respiratory disease. Enhanced vasoconstriction, pulmonary vascular remodeling, and in situ thrombosis contribute to the increased pulmonary vascular resistance observed in PH associated with hypoxic lung disease. The tissue factor pathway regulates fibrin deposition in response to acute and chronic vascular injury. We hypothesized that inhibition of the tissue factor pathway would result in attenuation of pathophysiologic parameters typically associated with hypoxia-induced PH. We tested this hypothesis using a chronic hypoxia-induced murine model of PH using mice that overexpress tissue factor pathway inhibitor (TFPI) via the smooth muscle-specific promoter SM22 (TFPI(SM22)). TFPI(SM22) mice have increased pulmonary TFPI expression compared with wild-type (WT) mice. In WT mice, exposure to chronic hypoxia (28 d at 10% O(2)) resulted in increased systolic right ventricular and mean pulmonary arterial pressures, changes that were significantly reduced in TFPI(SM22) mice. Chronic hypoxia also resulted in significant pulmonary vascular muscularization in WT mice, which was significantly reduced in TFPI(SM22) mice. Given the pleiotropic effects of TFPI, autocrine and paracrine mechanisms for these hemodynamic effects were considered. TFPI(SM22) mice had less pulmonary fibrin deposition than WT mice at 3 days after exposure to hypoxia, which is consistent with the antithrombotic effects of TFPI. Additionally, TFPI(SM22) mice had a significant reduction in the number of proliferating (proliferating cell nuclear antigen positive) pulmonary vascular smooth muscle cells compared with WT mice, which is consistent with in vitro findings. These findings demonstrate that overexpression of TFPI results in improved hemodynamic performance and reduced pulmonary vascular remodeling in a murine model of hypoxia-induced PH. This improvement is in part due to the autocrine and paracrine effects of TFPI overexpression.
American Journal of Respiratory Cell and Molecular Biology 08/2009; 43(1):35-45. · 5.13 Impact Factor
-
Shuchong Pan,
Horng H Chen,
Deborah M Dickey,
Guido Boerrigter,
Candace Lee, Laurel S Kleppe,
Jennifer L Hall,
Amir Lerman,
Margaret M Redfield,
Lincoln R Potter,
John C Burnett,
Robert D Simari
[show abstract]
[hide abstract]
ABSTRACT: Alternative RNA splicing may provide unique opportunities to identify drug targets and therapeutics. We identified an alternative spliced transcript for B-type natriuretic peptide (BNP) resulting from intronic retention. This transcript is present in failing human hearts and is reduced following mechanical unloading. The intron-retained transcript would generate a unique 34 amino acid (aa) carboxyl terminus while maintaining the remaining structure of native BNP. We generated antisera to this carboxyl terminus and identified immunoreactivity in failing human heart tissue. The alternatively spliced peptide (ASBNP) was synthesized and unlike BNP, failed to stimulate cGMP in vascular cells or vasorelax preconstricted arterial rings. This suggests that ASBNP may lack the dose-limiting effects of recombinant BNP. Given structural considerations, a carboxyl-terminal truncated form of ASBNP was generated (ASBNP.1) and was determined to retain the ability of BNP to stimulate cGMP in canine glomerular isolates and cultured human mesangial cells but lacked similar effects in vascular cells. In a canine-pacing model of heart failure, systemic infusion of ASBNP.1 did not alter mean arterial pressure but increased the glomerular filtration rate (GFR), suppressed plasma renin and angiotensin, while inducing natriuresis and diuresis. Consistent with its distinct in vivo effects, the activity of ASBNP.1 may not be explained through binding and activation of NPR-A or NPR-B. Thus, the biodesigner peptide ASBNP.1 enhances GFR associated with heart failure while lacking the vasoactive properties of BNP. These findings demonstrate that peptides with unique properties may be designed based on products of alternatively splicing.
Proceedings of the National Academy of Sciences 07/2009; 106(27):11282-7. · 9.68 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Tissue factor pathway inhibitor (TFPI) is a Kunitz-type protease inhibitor that regulates the extrinsic pathway of coagulation by inhibiting the factor VIIa/tissue factor (TF) catalytic complex. TFPI is expressed by both endothelial and smooth muscle cells in the vasculature and circulates at low levels. The role of local vascular TFPI in thrombosis and the development of vascular disease is unknown. To establish an experimental animal model to directly modulate smooth muscle cell-derived TFPI on the development of arterial thrombosis, transgenic mice in which a cDNA encoding murine TFPI is expressed from the murine SM22alpha promoter were generated. Expression of transgenic mRNA was 4-fold higher than the level of endogenous TFPI mRNA in arteries from transgenic mice. In situ hybridization confirmed that expression of the transgene was limited to medial vascular smooth muscle cells. Vascular TFPI activity was increased to 2 to 3-fold in carotid homogenates. There was no difference in plasma TFPI levels or hemostatic measures (PT, aPTT and tail vein bleeding times) between these mice and their wildtype littermates. In a ferric chloride-induced model of carotid thrombosis, homozygotic transgenic mice demonstrated resistance to thrombotic occlusion compared to wildtype littermates. In transgenic mice 22% occluded within 30 minutes of application while 84% of wild type mice occluded within the same time frame (p<0.01). Heterozygotic transgenic mice had an intermediate thrombotic phenotype. Taken together, these data indicated that local VSMC-specific TFPI overexpression attenuated ferric chloride-induced thrombosis without systemic or hemostatic effects. Furthermore, this transgenic mouse model should prove useful for studying the role of TFPI in the development and progression of vascular disease.
Thrombosis and Haemostasis 09/2004; 92(3):495-502. · 5.04 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Delivery of a heterogeneous population of cells with endothelial phenotype derived from peripheral blood has been shown to improve vascular responses after balloon arterial injury in an endothelium-dependent manner. Refinement of culture techniques has enabled the generation of outgrowth endothelial cells (OECs), a homogeneous population of distinctly endothelial cells expanded from circulating progenitor cells. The present study tested the hypothesis that OEC delivery would confer vascular protection after balloon arterial injury in a rabbit model. Rabbit peripheral blood mononuclear cells (PBMCs) were cultured in endothelial growth medium for 4-5 wk, yielding proliferative OECs with distinct endothelial phenotype (morphology, incorporation of acetylated LDL, and expression of endothelial nitric oxide synthase and caveolin-1 but not CD14). Animals underwent balloon carotid injury immediately followed by local delivery of autologous OECs for 20 min. Fluorescent-labeled OECs were detected in all layers at 4 wk, with immunostaining revealing maintenance of endothelial phenotype (von Willebrand factor-positive and RAM-11-negative) by luminal and nonluminal cells. To evaluate functional effects, additional animals received autologous OECs, saline, or freshly harvested PBMCs as noncultured cell controls by local dwell after balloon injury. Local OEC delivery improved endothelium-dependent vasoreactivity (P < 0.05 vs. saline and PBMC) and similarly reduced neointimal formation (P < 0.05 vs. saline and PBMC). These data suggest that OECs can be detected in injured arterial segments at 4 wk. Moreover, delivery of OECs confers greater vascular protection than PBMCs or saline controls and may thus offer a novel, autologous strategy to limit the response to mechanical injury.
AJP Heart and Circulatory Physiology 08/2004; 287(2):H512-7. · 3.71 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Caveolin-1 is a regulator of signaling events originating from plasma membrane microdomains termed caveolae. This study was performed to determine the regulatory role of caveolin-1 on the proliferative events induced by platelet-derived growth factor (PDGF) in vascular smooth muscle cells (VSMCs).
Treatment of VSMCs with PDGF for 24 hours resulted in a loss of caveolin-1 protein expression and plasma membrane-associated caveolae, despite a 3-fold increase in caveolin-1 mRNA. Pretreatment of VSMCs with chloroquine, an inhibitor of lysosomal function, inhibited the PDGF-induced loss of caveolin-1. These studies demonstrated that caveolin-1 was a target of PDGF signaling events. Adenoviral overexpression of caveolin-1 was associated with a switch in PDGF-induced signaling events from a proliferative response to an apoptotic response. This overexpression inhibited PDGF-induced expression of cyclin D1 in the presence of unaffected mitogen-activated protein kinase activation.
Taken together, these studies suggest that caveolin-1 is an inhibitor of PDGF proliferative responses and might be capable of transforming PDGF-induced proliferative signals into death signals.
Arteriosclerosis Thrombosis and Vascular Biology 10/2003; 23(9):1521-7. · 6.37 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Bone marrow-derived cells have been shown to contribute to endothelial replacement after vascular injury. In vitro culture of peripheral blood mononuclear cells produces cells with phenotypic characteristics of endothelium. To test the hypothesis that delivery of autologous culture-modified mononuclear cells (CMMCs) to injured arteries could attenuate the vascular response to injury, a rabbit model was studied.
Rabbit peripheral blood mononuclear cells were cultured in endothelial growth media for 7 to 12 days, yielding highly proliferative cells with distinct endothelial phenotype (expressing CD31 and endothelial nitric oxide synthase and capable of acetylated LDL uptake). A rabbit model of balloon carotid injury was used to evaluate the effect of day 7 CMMC delivery on vascular responses. Animals underwent balloon injury and immediate delivery of autologous CMMCs or buffered saline by 20 minutes of local dwelling. Fluorescence-labeled CMMCs were detected in all vessel layers 4 weeks after delivery. Colonies of cells that localized to the lumen and stained for endothelial markers were also identified. Local CMMC administration at the time of balloon injury accelerated reendothelialization at 4 weeks compared with saline (P<0.05). Moreover, CMMC delivery markedly improved endothelium-dependent vasoreactivity at 4 weeks compared with saline (P<0.005). Finally, CMMC treatment reduced neointimal formation by 55% at 4 weeks (P<0.05).
These data demonstrate that delivery of CMMCs to balloon-injured arteries is associated with accelerated reendothelialization, enhanced endothelium-dependent vasoreactivity, and reduced neointimal formation. Thus, delivery of autologous CMMCs represents a novel vasculoprotective approach to attenuate the response to acute vascular injury.
Circulation 09/2003; 108(12):1520-6. · 14.74 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Tissue factor (TF) is a small-molecular-weight glycoprotein that initiates the extrinsic coagulation pathway but may have important noncoagulation vascular functions as well. Tissue factor pathway inhibitor (TFPI) is a major physiological inhibitor of TF-initiated coagulation. Enhancement of vascular TFPI either by overexpression using gene transfer or delivery of protein to the vessel has been shown to reduce neointimal formation. However, the inherent role of TFPI in this process has not been defined. To do so, we utilized a murine model of vascular remodeling using flow cessation in mice, which are heterozygous for a genetic deletion of the first Kunitz domain of TFPI or wild type littermates. The heterozygotic mice had 50% of wild type TFPI activity in plasma as well as vascular homogenates. To study the effect of TFPI deficiency on neointimal formation, age matched TFPI(K1)+/- and wildtype littermates underwent unilateral common carotid artery ligation. Mice were sacrificed at 4 weeks and the ligated carotid arteries were analyzed. There was a significantly greater neointima to media ratio and less luminal area in the TFPI(K1)+/- mice compared to their TFPI(K1)+/+ littermates. The proliferative index of intimal cells in TFPI(K1)+/- mice at 1 week was significantly higher compared to TFPI(K1)+/+ mice. We conclude that TFPI deficiency enhances neointimal formation and proliferation associated with flow cessation. This suggests that TFPI may regulate vascular remodeling primarily through modulation of neointimal formation.
Thrombosis and Haemostasis 05/2003; 89(4):747-51. · 5.04 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Cells with an endothelial phenotype can be cultured from peripheral blood. These cells include cells of a monocytic origin with endothelial features (culture-modified mononuclear cells, CMMCs) and, at later time points, blood outgrowth endothelial cells (BOECs). Both are promising candidates for systemic cell-based cardiovascular therapies and each may have unique capabilities. Indeed, the combined use of both cell types has been shown to have synergistic therapeutic features requiring simultaneous delivery. However, the majority of preclinical studies of cell delivery have used splenectomized animals to increase systemic distribution. The goal of this study was to directly compare the distribution of these two cell types following systemic delivery in an intact animal model. A similar pattern of delivery was seen following delivery of both cell types with detection in the lung, liver, bone marrow, and spleen. Taken together, the data suggest that strategies using systemic delivery of circulation-derived cells must consider the distribution and efficiency of delivery in intact animals.
Endothelium 14(1):1-5. · 1.65 Impact Factor
