Simari, Robert D.

Rationale : Macrophages regulate blood vessel structure and function in health and disease. The origins of tissue macrophages are diverse, with evidence for local production and circulatory renewal. Objective : We identified a vascular adventitial population containing macrophage progenitor cells and investigated their origins and fate. Methods and Results : Single-cell disaggregates from adult C57BL/6 mice were prepared from different tissues and tested for their capacity to form hematopoietic colony-forming units. Aorta showed a unique predilection for generating macrophage colony-forming units. Aortic macrophage colony-forming unit progenitors coexpressed stem cell antigen-1 and CD45 and were adventitially located, where they were the predominant source of proliferating cells in the aortic wall. Aortic Sca-1 + CD45 + cells were transcriptionally and phenotypically distinct from neighboring cells lacking stem cell antigen-1 or CD45 and contained a proliferative (Ki67 + ) Lin − c-Kit + CD135 − CD115 + CX 3 CR1 + Ly6C + CD11b − subpopulation, consistent with the immunophenotypic profile of macrophage progenitors. Adoptive transfer studies revealed that Sca-1 + CD45 + adventitial macrophage progenitor cells were not replenished via the circulation from bone marrow or spleen, nor was their prevalence diminished by depletion of monocytes or macrophages by liposomal clodronate treatment or genetic deficiency of macrophage colony-stimulating factor. Rather adventitial macrophage progenitor cells were upregulated in hyperlipidemic ApoE −/− and LDL-R −/− mice, with adventitial transfer experiments demonstrating their durable contribution to macrophage progeny particularly in the adventitia, and to a lesser extent the atheroma, of atherosclerotic carotid arteries. Conclusions : The discovery and characterization of resident vascular adventitial macrophage progenitor cells provides new insight into adventitial biology and its participation in atherosclerosis and provokes consideration of the broader existence of local macrophage progenitors in other tissues.

To understand the role of bone marrow mononuclear cells in the treatment of acute myocardial infarction, this overview offers a retrospective examination of strengths and limitations of 3 contemporaneous trials with attention to critical design features and provides an analysis of the combined data set and implications for future directions in cell therapy for acute myocardial infarction.

Background— The impact of changing demographics on causes of long-term death after percutaneous coronary intervention (PCI) remains incompletely defined. Methods and Results— We evaluated trends in cause-specific long-term mortality after index PCI performed at a single center from 1991 to 2008. Deaths were ascertained by scheduled prospective surveillance. Cause was determined via telephone interviews, medical records, autopsy reports, and death certificates. Competing-risks analysis of cause-specific mortality was performed using 3 time periods of PCI (1991–1996, 1997–2002, and 2003–2008). Final follow-up was December 31, 2012. A total of 19 077 patients survived index PCI hospitalization, of whom 6988 subsequently died (37%, 4.48 per 100 person-years). Cause was determined in 6857 (98.1%). Across 3 time periods, there was a 33% decline in cardiac deaths at 5 years after PCI (incidence: 9.8%, 7.4%, and 6.6%) but a 57% increase in noncardiac deaths (7.1%, 8.5%, and 11.2%). Only 36.8% of deaths in the recent era were cardiac. Similar trends were observed regardless of age, extent of coronary disease, or PCI indication. After adjustment for baseline variables, there was a 50% temporal decline in cardiac mortality but no change in noncardiac mortality. The decline in cardiac mortality was driven by fewer deaths from myocardial infarction/sudden death ( P <0.001) but not heart failure ( P =0.85). The increase in noncardiac mortality was primarily attributable to cancer and chronic diseases ( P <0.001). Conclusions— This study found a marked temporal switch from predominantly cardiac to predominantly noncardiac causes of death after PCI over 2 decades. The decline in cardiac mortality was independent of changes in baseline clinical characteristics. These findings have implications for patient care and clinical trial design.

Ultrasound (US) enhancement of plasmid-based gene transfer is an emerging technique. Our hypothesis was that two contrast agents (Optison and PESDA), and two US exposure modalities (dedicated continuous wave system and diagnostic scanner) may have different effects. Luciferase plasmid with or without contrast agent was added to vascular smooth muscle cells and endothelial cells, followed by US exposure. Luciferase activity was measured 24 h later. US exposure consistently induced higher transfection rates than all controls. PESDA was superior to Optison in both cell lines. In vitro, continuous wave and diagnostic US were not significantly different. In vivo, Lux and PESDA were injected into skeletal muscles of rats (IM or intra-arterial) followed or not by US exposure. In separate animals, adenovirus encoding for luciferase was injected IM and was not followed by US exposure. Gene transfer efficacy was 8–10 fold higher with US and PESDA than with plasmid alone, but 2 fold lower than with adenovirus. However, as opposed to adenovirus, US-enhanced plasmid gene transfer was highly localized to the injected muscle, with no expression at distal sites. Our results support the hypothesis that contrast agents and exposure modalities are not equivalent with regard to gene transfer efficacy.

Objective— Endothelial outgrowth cells (EOC) decrease inflammation and improve endothelial repair. Inflammation aggravates kidney injury in renal artery stenosis (RAS), and may account for its persistence upon revascularization. We hypothesized that EOC would decrease inflammatory (M1) macrophages and improve renal recovery in RAS. Approach and Results— Pigs with 10 weeks of RAS were studied 4 weeks after percutaneous transluminal renal angioplasty (PTRA+stenting) or sham, with or without adjunct intrarenal delivery of autologous EOC (10×10 6 ), and compared with similarly treated normal controls (n=7 each). Single-kidney function, microvascular and tissue remodeling, inflammation, oxidative stress, and fibrosis were evaluated. Four weeks after PTRA, EOC were engrafted in injected RAS-kidneys. Stenotic-kidney glomerular filtration rate was restored in RAS+EOC, RAS+PTRA, and RAS+PTRA+EOC pigs, whereas stenotic-kidney blood flow and angiogenesis were improved and fibrosis attenuated only in EOC-treated pigs. Furthermore, EOC increased cell proliferation and decreased the ratio of M1 (inflammatory)/M2 (reparative) macrophages, as well as circulating levels and stenotic-kidney release of inflammatory cytokines. Cultured-EOC released microvesicles in vitro and induced phenotypic switch (M1-to-M2) in cultured monocytes, which was inhibited by vascular endothelial growth factor blockade. Finally, a single intrarenal injection of rh-vascular endothelial growth factor (0.05 μg/kg) in 7 additional RAS pigs also restored M1/M2 ratio 4 weeks later. Conclusions— Intrarenal infusion of EOC after PTRA induced a vascular endothelial growth factor–mediated attenuation in macrophages inflammatory phenotype, preserved microvascular architecture and function, and decreased inflammation and fibrosis in the stenotic kidney, suggesting a novel mechanism and therapeutic potential for adjunctive EOC delivery in experimental RAS to improve PTRA outcomes.

Renal artery stenosis (RAS) is an important cause of chronic renal dysfunction. Recent studies have underscored a critical role for CCL2 (MCP-1)-mediated inflammation in the progression of chronic renal damage in RAS and other chronic renal diseases. In vitro studies have implicated p38 MAPK as a critical intermediate for the production of CCL2. However, a potential role of p38 signaling in the development and progression of chronic renal disease in RAS has not been previously defined. We sought to test the hypothesis that inhibition of p38 MAPK ameliorates chronic renal injury in mice with RAS. We established a murine RAS model by placing a cuff on the right renal artery and treated mice with the p38 inhibitor SB203580 or vehicle for 2 wk. In mice treated with vehicle, the cuffed kidney developed interstitial fibrosis, tubular atrophy, and interstitial inflammation. In mice treated with SB203580, the RAS-induced renal atrophy was reduced (70% vs. 39%, P < 0.05). SB203580 also reduced interstitial inflammation and extracellular matrix deposition but had no effect on the development of hypertension. SB203580 partially blocked the induction of CCL2, CCL7 (MCP-3), CC chemokine receptor 2 (CCR2), and collagen 4 mRNA expression in the cuffed kidneys. In vitro, blockade of p38 hindered both TNF-α and TGF-β-induced CCL2 upregulation. Based on these observations, we conclude that p38 MAPK plays a critical role in the induction of CCL2/CCL7/CCR2 system and the development of interstitial inflammation in RAS.

Background— Spontaneous coronary artery dissection (SCAD) is an acute coronary event of uncertain origin. Clinical features and prognosis remain insufficiently characterized. Methods and Results— A retrospective single-center cohort study identified 87 patients with angiographically confirmed SCAD. Incidence, clinical characteristics, treatment modalities, in-hospital outcomes, and long-term risk of SCAD recurrence or major adverse cardiac events were evaluated. Mean age was 42.6 years; 82% were female. Extreme exertion at SCAD onset was more frequent in men (7 of 16 versus 2 of 71; P <0.001), and postpartum status was observed in 13 of 71 women (18%). Presentation was ST-elevation myocardial infarction in 49%. Multivessel SCAD was found in 23%. Initial conservative management (31 of 87) and coronary artery bypass grafting (7 of 87) were associated with an uncomplicated in-hospital course, whereas percutaneous coronary intervention was complicated by technical failure in 15 of 43 patients (35%) and 1 death. During a median follow-up of 47 months (interquartile range, 18–106 months), SCAD recurred in 15 patients, all female. Estimated 10-year rate of major adverse cardiac events (death, heart failure, myocardial infarction, and SCAD recurrence) was 47%. Fibromuscular dysplasia of the iliac artery was identified incidentally in 8 of 16 femoral angiograms (50%) undertaken before closure device placement and in the carotid arteries of 2 others with carotid dissection. Conclusions— SCAD affects a young, predominantly female population, frequently presenting as ST-elevation myocardial infarction. Although in-hospital mortality is low regardless of initial treatment, percutaneous coronary intervention is associated with high rates of complication. Risks of SCAD recurrence and major adverse cardiac events in the long term emphasize the need for close follow-up. Fibromuscular dysplasia is a novel association and potentially causative factor.

Abstract —Adrenomedullin, originally discovered in human pheochromocytoma, is a vasodilating and natriuretic peptide of vascular endothelial and smooth muscle cell origin. Although endothelin-1 (ET-1) has been implicated as a vasoconstricting and growth-promoting peptide of endothelial origin, it may more importantly function as an autocrine factor and release vasodilatory substances such as nitric oxide by mechanisms linked to the endothelin-B (ET B ) receptor subtype. The present study was designed to establish that the ET B receptor stimulates the secretion of adrenomedullin from cultured canine aortic endothelial cells. We first sought to determine the presence and production of adrenomedullin in canine aortic endothelial cells using immunohistochemistry and Northern blot analysis, which revealed that adrenomedullin immunoreactivity and adrenomedullin mRNA were present in canine aortic endothelial cells. Second, adrenomedullin was time-dependently secreted from canine aortic endothelial cells, with a secretion rate of 15.7±1.5 pg/10 5 cells per 24 hours. Furthermore, immunohistochemistry revealed the presence of the ET B receptor in canine aortic endothelial cells, and ET B receptor stimulation by sarafotoxin S6c increased adrenomedullin production and secretion from canine aortic endothelial cells. Such actions were blocked with the ET B receptor antagonist IRL-2500 but not with ET A receptor antagonist FR-139317. These studies are the first to report an additional autocrine role of the ET B receptor in the release of vasodilating and natriuretic peptide adrenomedullin, and they suggest another important vasoactive system regulated by the ET receptor subtype.