Oral delivery of fluticasone powder improves esophageal eosinophilic inflammation and symptoms in adults with eosinophilic esophagitis

Topical steroids are the primary medical therapy for eosinophilic esophagitis (EoE). Current steroid formulations are used off-label and designed for airway delivery. It is known that the efficacy of topical steroids depends on drug-mucosal contact time, which is related to its formulation. The purpose of this study is to examine the effectiveness of fluticasone administered by means of an orally administered powder formulation. We conducted a retrospective analysis of patients diagnosed with EoE based on current guidelines and who were treated with orally administered fluticasone powder. The primary outcome was histologic response (peak eosinophil density (eos/hpf)). Secondary outcomes included patient-reported symptoms (EoEQ) and endoscopic features measured by a validated instrument (EoE endoscopic reference score, EREFS). Forty patients were treated with fluticasone powder with doses of 500 to 1000 mcg b.i.d. A significant difference was found between pre- and posttreatment levels of eosinophilia (P < 0.0001). Seventy-five percent of patients achieved peak densities of <15 eos/hpf. Improvement was also demonstrated in dysphagia symptoms (P = 0.031) and endoscopic findings of furrows (P = 0.0001) and exudates (P = 0.0001). Oral fluticasone powder induced significant improvement in histopathology, symptoms, and endoscopic features of inflammation in adults with EoE. It offers an easy-to-administer formulation of a topical steroid that circumvents concerns with esophageal delivery of commonly used, aerosolized inhaler preparations.

Prospective assessment of disease-specific quality of life in adults with eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is an important cause of upper gastrointestinal dysfunction in children and adults. The EoE-quality of life (QOL)-A was validated as a disease-specific measure of quality of life in EoE. This study characterized the extent of QOL concerns in a cohort of adult EoE patients and delineated the relationships between QOL and other disease activity measures. One hundred sixty-seven patients enrolled in this prospective cohort study. Patients with established and suspected EoE undergoing endoscopy at a single university-based medical center were recruited. EoE was diagnosed on the basis of the clinical criteria and histologic demonstration of ≥15 eos/hpf while on proton pump inhibition therapy. Sixty five patients undergoing repeat endoscopy during the enrollment period participated twice. Patients provided demographic information and completed symptom assessments and the EoE-QOL-A. Analyses included comparisons with overall QOL as well as QOL subscales. Outcome measures included endoscopic activity using a validated instrument, the EoE Endoscopic Reference Score, and histology. Overall QOL was significantly correlated with dysphagia frequency, intensity, and severity (P < 0.001). Patients who experienced a food impaction in the last 30 days had significantly worse overall QOL (P = 0.009). There was no correlation between overall QOL and years since diagnosis, symptom duration, endoscopic features, or histologic findings. Patient symptoms correlated with endoscopic features of edema, rings, and stricture severity. Histologic activity was highly correlated with severity of endoscopic features. Patients who underwent repeat endoscopy with histologic response demonstrated improved eating and social QOL; however, overall QOL was unchanged. In adults with EoE, patient reported QOL is associated with symptom severity but not endoscopic or histologic features. Disease-specific QOL may complement parameters of biologic activity in the assessment of overall disease burden in EoE.

Evaluation of esophageal distensibility in eosinophilic esophagitis: an update and comparison of functional lumen imaging probe analytic methods

BACKGROUND

Distensibility evaluation of the esophageal body using the functional lumen imaging probe (FLIP) offers an objective measure to characterize patients with eosinophilic esophagitis (EoE), though this analysis may be limited by unrecognized catheter movement and esophageal contractility. The aims of this study were to report novel FLIP analytic methods of esophageal distensibility measurement in EoE and to assess the effect of contractility.

METHODS

Nine healthy controls (six female; ages 20-49) and 20 EoE patients (four female; ages 19-64; grouped by degree of distension-mediated contractility identified on FLIP) were evaluated with a 16-cm FLIP device during step-wise balloon distension during upper endoscopy. A distensibility plateau (DP) was generated using multiple methods to identify the narrowest esophageal body diameter: (i) wavelet decomposition (WD), (ii) maximal diameter (MD), and (iii) FLIP Analytics software.

KEY RESULTS

Distensibility was reduced in EoE patients compared with controls using the WD (p = 0.002) and MD (p = 0.001) methods; a trend was detected using the FLIP Analytics method (p = 0.055). Significant intra-subject differences were detected between methods among both patients and controls (p-values <0.001 to 0.025); the difference was more pronounced among subjects with a greater degree of contractility. DP was <19 mm among 7/9 controls with FLIP Analytics, 6/9 controls with WD, and 0/9 controls using the MD method.

CONCLUSIONS & INFERENCES

Distension-mediated contractility affects distensibility measurement with the FLIP. Using software-based algorithms, particularly with a method that identifies the maximal-achieved diameters (MD), may improve objective distensibility measurement for clinical research and practice.

Collaborative meta-analysis of individual participant data from observational studies of Lp-PLA2 and cardiovascular diseases

BACKGROUND

A large number of observational epidemiological studies have reported generally positive associations between circulating mass and activity levels of lipoprotein-associated phospholipase A2 (Lp-PLA2) and the risk of cardiovascular diseases. Few studies have been large enough to provide reliable estimates in different circumstances, such as in different subgroups (e.g., by age group, sex, or smoking status) or at different Lp-PLA2 levels. Moreover, most published studies have related disease risk only to baseline values of Lp-PLA2 markers (which can lead to substantial underestimation of any risk relationships because of within-person variability over time) and have used different approaches to adjustment for possible confounding factors.

OBJECTIVES

By combination of data from individual participants from all relevant observational studies in a systematic 'meta-analysis', with correction for regression dilution (using available data on serial measurements of Lp-PLA2), the Lp-PLA2 Studies Collaboration will aim to characterize more precisely than has previously been possible the strength and shape of the age and sex-specific associations of plasma Lp-PLA2 with coronary heart disease (and, where data are sufficient, with other vascular diseases, such as ischaemic stroke). It will also help to determine to what extent such associations are independent of possible confounding factors and to explore potential sources of heterogeneity among studies, such as those related to assay methods and study design. It is anticipated that the present collaboration will serve as a framework to investigate related questions on Lp-PLA2 and cardiovascular outcomes.

METHODS

A central database is being established containing data on circulating Lp-PLA2 values, sex and other potential confounding factors, age at baseline Lp-PLA2 measurement, age at event or at last follow-up, major vascular morbidity and cause-specific mortality. Information about any repeat measurements of Lp-PLA2 and potential confounding factors has been sought to allow adjustment for possible confounding and correction for regression dilution. The analyses will involve age-specific regression models. Synthesis of the available observational studies of Lp-PLA2 will yield information on a total of about 15 000 cardiovascular disease endpoints.

The compensatory potential of increased immigration following intensive American mink population control is diluted by male-biased dispersal

Attempts to mitigate the impact of invasive species on native ecosystems increasingly target large land masses where control, rather than eradication, is the management objective. Depressing numbers of invasive species to a level where their impact on native biodiversity is tolerable requires overcoming the impact of compensatory immigration from non-controlled portions of the landscape. Because of the expected scale-dependency of dispersal, the overall size of invasive species management areas relative to the dispersal ability of the controlled species will determine the size of any effectively conserved core area unaffected by immigration from surrounding areas. However, when dispersal is male-biased, as in many mammalian invasive carnivores, males may be overrepresented amongst immigrants, reducing the potential growth rate of invasive species populations in re-invaded areas. Using data collected from a project that gradually imposed spatially comprehensive control on invasive American mink (Neovison vison) over a 10,000 km² area of NE Scotland, we show that mink captures were reduced to almost zero in 3 years, whilst there was a threefold increase in the proportion of male immigrants. Dispersal was often long distance and linking adjacent river catchments, asymptoting at 38 and 31 km for males and females respectively. Breeding and dispersal were spatially heterogeneous, with 40 % of river sections accounting for most captures of juvenile (85 %), adult female (65 %) and immigrant (57 %) mink. Concentrating control effort on such areas, so as to turn them into “attractive dispersal sinks” could make a disproportionate contribution to the management of recurrent re-invasion of mainland invasive species management areas.

Population genetic structure in farm and feral American mink (Neovison vison) inferred from RAD sequencing-generated single nucleotide polymorphisms

Feral American mink populations (), derived from mink farms, are widespread in Europe. In this study we investigated genetic diversity and genetic differentiation between feral and farm mink using a panel of genetic markers (194 SNP) generated from RAD sequencing data. Sampling included a total of 211 individuals from 14 populations, 4 feral and 10 from farms, the latter including a total of 7 color types (Brown, Black, Mahogany, Sapphire, White, Pearl, and Silver). Our study revealed similar low levels of genetic diversity in both farm and feral mink. Results are consistent with small effective population size as a consequence of line selection in the farms and founder effects of a few escapees from the farms in feral populations. Moderately high genetic differentiation was found between farm and feral animals, suggesting a scenario in which wild populations were founded from farm escapes a few decades ago. Currently, escapes and gene flow are probably limited. Genetic differentiation was higher among farm color types than among farms, consistent with line selection using few individuals to create the lines. Finally, no indications of inbreeding were found in either farm or feral samples, with significant negative values found in most farm samples, showing farms are successful in avoiding inbreeding.

Prospective assessment of the diagnostic utility of esophageal brushings in adults with eosinophilic esophagitis

Patients with eosinophilic esophagitis (EoE) undergo multiple endoscopies with biopsy for both diagnosis and assessment of treatment response, which is inconvenient and costly. Brush cytology has been examined in Barrett's esophagus to reduce the need for repeated endoscopic biopsies. The aim of this pilot study was to evaluate the ability of brush cytology to detect mucosal eosinophilia in patients with EoE. This prospective study included adults with untreated and treated esophageal eosinophilia undergoing endoscopy at a tertiary care center. Patients received paired brushings and biopsies at the proximal and distal esophagus. A blinded pathologist quantified the number of eosinophils and epithelial cells per high-power field (hpf) on the cytology slides. The ratio of eosinophils/epithelial cells was used to normalize the cytology specimens for density of cells collected. The main outcome measures were sensitivity and specificity of brush cytology, and correlation between cytology and histology. Twenty-eight patients enrolled. The average age of the cohort was 37.7 ± 10.4 years; 75% of subjects were male. The sensitivity of cytology was 67-69% at the proximal esophagus and 70-72% at the distal esophagus. The specificity was 61-67% proximally and 70-75% distally. Histology was not significantly correlated with the max ratio of eosinophils/epithelial cells per hpf or the absolute number of eosinophils on cytology slides. Cytology using esophageal brushing has limited sensitivity and specificity for the detection of esophageal mucosal eosinophilia. The presence of exudates on endoscopy increased the detection of eosinophilia, which could make cytology useful in pediatric EoE, which often has a more exudative presentation. Diagnostic yield may improve with alternative acquisition techniques or the incorporation of eosinophil degranulation proteins.

Dysregulation of the Wnt pathway in adult eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a chronic inflammatory disease characterized pathologically by eosinophil infiltration. In addition to loss of barrier integrity, a dominant T Helper 2-associated immune response and strong allergic connection, the esophagus tissue undergoes dramatic changes, with frequent presence of mucosal rings, strictures, linear furrows, and trachealization. Although the inflammatory mechanisms behind this disease are being increasingly well understood, the structural features remain unexplained. We examined the expression of key members of the Wnt-signaling pathway in biopsies from patients with EoE. This pathway has been shown to be critically important in regulating cellular homeostasis, growth, and differentiation and to be dysregulated in several disease conditions. Biopsies from adult EoE patients were collected by endoscopy and mRNA extracted. After cDNA synthesis, the relative gene expression from key upstream (secreted frizzled-related protein 1) and downstream (c-myc and Cyclin D1) molecules in the Wnt pathway, as well as several Wnt pathway members (Wnt1, Axin1, low-density lipoprotein receptor-related protein 6, glycogen synthase kinase 3 beta, and β-catenin), were determined. Biopsies from patients with EoE displayed significantly higher expression of secreted frizzed-related protein 1 than controls, as well as reductions in Cyclin D1 and c-myc. In contrast, there were no differences in the Wnt pathway molecules. The levels of expression of Cyclin D1 and c-myc, as well as β-catenin, in EoE patients showed strong correlations with the frequency of esophageal eosinophils. Our findings suggest that although there are no changes in the overall levels of key Wnt pathway genes in adult EoE, there is evidence for dysregulation of upstream and downstream regulators of Wnt signaling. Importantly, the associations with eosinophilia suggest that these may participate in the pathogenesis of this disease and be markers of disease severity.

Population viability analysis of American mink (Neovison vison) escaped from Danish mink farms

The American mink (Neovison vison) was introduced to Danish fur farms in the 1930s. An unknown number of mink have managed to escape these farms over the years. Today feral mink are found in the wild in most parts of Denmark. A population viability analysis (PVA) was performed using VORTEX, a stochastic population simulation software, to 1) predict the viability and potential population expansion from different sizes of founding populations of farm escapees, 2) investigate which parameters mostly affect the viability, 3) assess the effects of continuous escapes on the feral populations and how the feral populations are affected by management programs, and 4) discuss eradication strategies and their efficiency in management of the feral American mink population in Denmark. The simulations showed that juvenile mortality had the greatest effect on population viability followed by fecundity, adult mortality, and initial population size. Populations supplemented yearly by escapees all reached the carrying capacity and gained genetic variability over the years. Harvesting was modeled as the yearly number of mink caught in Denmark. Most of the simulated harvested populations crashed within few years after the first harvesting event. This indicates that the feral number of mink in Denmark is sustained due to supplements from mink farms and no true feral population exists. To manage the number of feral mink in Denmark it is essential to prevent escapees. The eradication effort would be most effective if focused on late summer and autumn when juvenile mink leave the maternal territory.

Inbreeding affects fecundity of American mink (Neovison vison) in Danish farm mink

Inbreeding is an increasing problem in farmed mink, because of limited exchange of individuals between farms. In this study, genetic relatedness within seven American mink (Neovison vison) colour strains originating from 13 different mink farms in Denmark was analysed using 21 polymorphic microsatellite loci. We detected large differences in the level of relatedness (range 0.017-0.520) within colour strains. Moreover, a very strong and highly significant negative correlation between the level of relatedness and fecundity was observed (r = 0.536, P < 0.001) [Correction added after online publication on 9 March 2011: r(2) has been changed to r]. To our knowledge, this is the first time that such a correlation has been demonstrated for commercially farmed mink.

Facilitative interactions between the Eurasian badger (Meles meles), the red fox (Vulpes vulpes), and the invasive raccoon dog (Nyctereutes procyonoides) in Białowieża Primeval Forest, Poland

Based on radio-tracking of Eurasian badgers ( Meles meles (L., 1758)), red foxes ( Vulpes vulpes (L., 1758)), and raccoon dogs ( Nyctereutes procyonoides (Gray, 1834)) and observations at burrows conducted in Białowieża Primeval Forest (eastern Poland) in 1996–2002, we addressed the hypothesis that facilitative interactions between a native (badger) and an alien (raccoon dog) species contributed to the invasion success of the latter. In winter, 88% of badger setts were occupied by both badgers and raccoon dogs, 4% by badgers and red foxes, and 4% by all three species. In summer, only 20% of badger setts were cohabited by other carnivore species (10% by raccoon dogs and 10% by foxes). Duration of occupation of badger setts by raccoon dogs averaged 117 days (SE = 21 days). Seasonal variation in raccoon dog use of badger setts was explained by changes in ambient temperature: the lower was the temperature, the higher was the rate of sett occupation by raccoon dogs. When wintering in the same sett, badgers and raccoon dogs used different parts of the sett. We conclude that facilitation by badgers (through habitat amelioration and refuge from cold and predation) makes the realized niche of raccoon dogs larger than predicted from their fundamental niche. The facilitating role of badger is stronger in winter, which is a critical period for raccoon dog survival in the temperate and boreal zone.

Lipoprotein-associated Phospholipase A2: A Potential Therapeutic Target for Atherosclerosis

Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) is an enzyme that is produced by inflammatory cells, is bound to circulating LDL, and is involved in hydrolyzing polar phospholipids, including those found in oxidized low-density lipoproteins. To date, the biological role of Lp-PLA(2) in atherogenesis has been controversial, with initial reports purporting an atheroprotective effect attributable to the degradation of platelet activating factor and similar molecules. However, more recent studies suggest a proatherogenic role for this enzyme, which is attributed to Lp-PLA(2)-mediated hydrolysis of oxidatively modified low-density lipoproteins that results in the accumulation of proinflammatory products. The liberation of lysophosphatidylcholine and oxidized nonesterified fatty acids from oxidized phospholipids by the action of Lp-PLA(2) results in diverse inflammatory effects on various cell types involved in atherogenesis. This concept is further supported by a number of recently published epidemiology studies suggesting that plasma levels of the enzyme predict future cardiovascular events independent of conventional risk factors. The development of selective inhibitors of Lp-PLA(2) that inhibit enzyme activity in the circulation as well as within human atherosclerotic lesions opens the possibility of therapeutic manipulation of vascular inflammatory processes to reduce residual cardiovascular events in high risk individuals who continue to suffer fatal and nonfatal events despite the current standard of care.

Oxidative Stress and Lipid Retention in Vascular Grafts

Background —Because saphenous vein grafts (SVGs) exhibit greater cellular heterogeneity and worse clinical outcomes than arterial grafts (AGs), we examined oxidative stress and lipid retention in different vascular conduits.

Methods and Results —In a porcine model of graft interposition into carotid artery, superoxide anion (·O 2 − ) was measured at 2 weeks after surgery. SVGs demonstrated increased ·O 2 − production compared with AGs (SOD-inhibitable nitro blue tetrazolium reduction, P <0.01). The NAD(P)H oxidase inhibitor diphenyleneiodonium ( P <0.01) abolished SVG-derived ·O 2 − , whereas the inhibitors of other pro-oxidant enzymes were ineffective. The change in oxidative stress was also reflected by lower activity of the endogenous antioxidant superoxide dismutase in SVGs than in AGs ( P <0.001). SVG remodeling was associated with increased synthesis of sulfated glycosaminoglycans and augmented expression of a core protein, versican. These changes were accompanied by SVGs retaining significantly more 125 I-labeled LDL than AGs ex vivo ( P <0.001). In hyperlipemic animals, lipid accumulation and oxidized epitopes were preferentially noted in the intima of SVGs at 1 month after surgery.

Conclusions —This study demonstrated significant differences in the biology of SVGs and AGs. SVGs exhibited higher oxidative stress, LDL accumulation, and the presence of oxidized epitopes. These findings suggest that proatherogenic changes in SVGs may commence early after surgical revascularization.

Increased NAD(P)H Oxidase and Reactive Oxygen Species in Coronary Arteries After Balloon Injury

Abstract —Reactive oxygen species (ROS), produced by cellular constituents of the arterial wall, provide a signaling mechanism involved in vascular remodeling. Because adventitial fibroblasts are actively involved in coronary remodeling, we examined whether the changes in the redox state affect their phenotypic characteristics. To this end, superoxide anion production and NAD(P)H oxidase activity were measured in porcine coronary arteries in vivo, and the effect of ROS generation on adventitial fibroblast proliferation was examined in vitro. Superoxide production (SOD- and Tiron-inhibitable nitro blue tetrazolium [NBT] reduction) increased significantly within 24 hours after balloon-induced injury, with the product of NBT reduction present predominantly in adventitial fibroblasts. These changes were NAD(P)H oxidase–dependent, because diphenyleneiodonium (DPI) abolished superoxide generation ( P <0.001). Furthermore, the injury-induced superoxide production was associated with augmented NAD(P)H oxidase activity and upregulation of p47 phox and p67 phox in adventitial fibroblasts (immunohistochemistry). Serum stimulation of isolated adventitial fibroblasts produced time-dependent increases in ROS production (peak 3 to 6 hours). The inhibition of ROS generation with NAD(P)H oxidase inhibitor (DPI) or the removal of ROS with antioxidants (Tiron, catalase) abrogated proliferation of adventitial fibroblasts. These results indicate that vascular NAD(P)H oxidase plays a central role in the upregulation of oxidative stress after coronary injury, providing pivotal growth signals for coronary fibroblasts.

Safety of intracoronary administration of c-myc antisense oligomers after percutaneous transluminal coronary angioplasty (PTCA)

We wished to assess the clinical safety and pharmacokinetics of ascending doses of a synthetic oligodeoxynucleotide (LR-3280) administered after coronary angioplasty. Antisense oligodeoxynucleotides designed to hybridize with target messenger ribonucleic acid (mRNA) in a complementary fashion to inhibit the expression of corresponding protein also have the ability to bind to extracellular growth factors. LR-3280 has been shown to reduce c-myc expression, inhibit growth and collagen biosynthesis in human vascular cells, and reduce neointimal formation in animal models of vascular injury. After successful percutaneous transluminal coronary angioplasty (PTCA), 78 patients were randomized to receive either standard care (n = 26) or standard care and escalating doses of LR-3280 (n = 52) (doses from 1 to 24 mg), administered into target vessel through a guiding catheter. Overall safety was evaluated by clinical adverse events, laboratory tests, and electrocardiograms. Patency was evaluated by quantitative coronary angiography. There were no clinically significant differences between treated and control patients. No adverse effects of LR-3280 on the patency of dilated coronary arteries were observed. Pharmacokinetic data revealed that peak plasma concentrations of LR-3280 occurred at 1 minute over the studied dose range and rapidly decreased after approximately1 hour, with little LR-3280 detected in the urine between 0-6 hours and 12-24 hours. The intracoronary administration of LR-3280 is well tolerated at doses up to 24 mg and produces no adverse effects in dilated coronary arteries. These results provide the basis for the evaluation of local delivery of this phosphorothioate oligodeoxynucleotide for the prevention of human vasculoproliferative disease.

Regional differences in integrin expression: role of alpha(5)beta(1) in regulating smooth muscle cell functions

There is increasing evidence to suggest that coronary smooth muscle cells (SMCs) differ from noncoronary SMCs. As integrin adhesion molecules regulate many SMC functions, we hypothesized that differences in integrin expression on coronary and noncoronary SMCs may account for cellular differences. Analysis of integrin expression on freshly isolated porcine coronary and noncoronary SMCs revealed that coronary SMCs express significantly less alpha(5)beta(1) than noncoronary SMCs, whereas the expression of total beta(1) and that of alpha(v)beta(3) are similar. Consistent with these findings, coronary SMCs demonstrated significantly less adhesion to fibronectin, compared with carotid artery SMCs. As alpha(5)beta(1)-mediated signaling has been associated with cellular proliferation, the effects of differential alpha(5)beta(1) expression on cell proliferation were examined by comparing primary coronary and carotid artery SMC proliferation. Coronary SMC growth was significantly lower than that of carotid artery SMCs when plated on fibronectin or type I collagen. Blocking alpha(5)beta(1) function on carotid artery SMCs produced a significant decrease in cellular proliferation, resulting in growth similar to that of coronary SMCs. Furthermore, blocking alpha(5)beta(1), but not alpha(v)beta(3), inhibited loss of alpha-smooth muscle actin in proliferating SMCs. Proliferating coronary SMCs were found to upregulate alpha(5)beta(1) expression, further indicating a role for alpha(5)beta(1) in SMC growth. These results suggest that dissimilar alpha(5)beta(1) integrin expression may mediate regional differences in phenotype of vascular SMCs.

Myofibroblast involvement in glycosaminoglycan synthesis and lipid retention during coronary repair

Myofibroblasts of adventitial origin have been linked to neointimal formation and remodeling after coronary injury. Accordingly, the goal of this study was to examine whether myofibroblasts contribute to focal accumulation of glycosaminoglycans (GAGs) and lipids during coronary repair. GAG synthesis was assessed by ex vivo labeling of balloon-injured porcine coronary arteries with (14)C-glucosamine. The synthesis of total GAGs transiently increased at 8 days in the normolipemic model (a 2.2-fold increase over baseline, p < 0.05). The majority of newly synthesized GAGs were sensitive to chondroitin ABC lyase (chondroitin/dermatan sulfate GAGs). Versican was localized to myofibroblast-rich regions in the adventitia and neointima [positive for alpha-smooth muscle (SM) actin, negative for h-caldesmon and SM myosin heavy chain]. In contrast, the adjacent SM-rich media showed no increase in versican expression. The association between injury-induced GAG accumulation and lipid retention was examined at 2 weeks after coronary injury in the hyperlipemic model. Lipid (Oil Red O) accumulated in the neointima and adventitia, but not in the adjacent media. Coronary repair under hyperlipemic conditions was associated with macrophage infiltration (19 +/- 5 vs. 3 +/- 2% of neointimal cells in normolipemic animals, p < 0.001) and increased neointimal formation (1.8 +/- 0.5 vs. 1.0 +/- 0.3 mm(2) in normolipemic animals, p < 0.01). In conclusion, this study demonstrated a transient increase in GAG synthesis following coronary injury. Chondroitin sulfate proteoglycans (e.g., versican) were rapidly synthesized by activated adventitial and neointimal cells which could contribute to early lipid retention in injured vessels.

Characteristics of coronary smooth muscle cells and adventitial fibroblasts

BACKGROUND

Recent findings suggesting the involvement of adventitial cells in coronary repair have raised questions regarding the phenotypic "plasticity" of medial smooth muscle cells (SMCs). Accordingly, the aims of the present study were to examine the characteristics of coronary medial and adventitial cells and to compare the responses of coronary and noncoronary SMCs to stimulation.

METHODS AND RESULTS

Enzymatically isolated coronary SMCs (human and porcine) were distinct from noncoronary SMCs, showing poor adhesion and spreading, as well as lower proliferation, collagen synthesis, and LDL degradation. Several extracellular matrix components (Matrigel, collagen I and IV, laminin, vitronectin, fibronectin) or growth factors (epidermal growth factor, platelet-derived growth factor-BB, insulin growth factor-1, interleukin-1alpha) failed to augment the adhesion or proliferation of coronary SMCs to the levels observed in noncoronary SMCs. Unlike coronary SMCs, coronary fibroblasts demonstrated high adhesion, proliferation, collagen synthesis, and avid LDL metabolism. Limited responses of coronary SMCs were associated with sustained expression of differentiation markers (alpha-smooth muscle actin, h-caldesmon, and smooth muscle myosin heavy chain), whereas noncoronary SMCs showed marked phenotypic heterogeneity.

CONCLUSIONS

Coronary SMCs appeared to maintain highly differentiated phenotype in response to stimulation, whereas coronary adventitial fibroblasts demonstrated several characteristics that are essential during vascular repair. Coronary SMCs, however, were distinct from noncoronary medial cells, which displayed greater phenotypic heterogeneity and versatility in culture. We postulate that the mechanism of vascular repair may differ among vascular beds, pointing to the importance of coronary artery-specific investigations in vascular biology.

Role of matrix metalloproteinases and their tissue inhibitors in the regulation of coronary cell migration

The migration of vascular cells is regulated by matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs). Because the activation of adventitial fibroblasts has been implicated in coronary repair, we have examined regional differences in cell outgrowth and the synthesis of MMPs/TIMPs in different layers of porcine coronary arteries. Coronary medial explants demonstrated significantly slower cell outgrowth than coronary adventitia in culture (P<0.001). These observations were paralleled by the predominant expression of TIMP-1 and -2 in the media (14-fold and 37-fold higher than in adventitia, respectively, P<0.001), whereas higher gelatinolytic activities (MMP-2 and -9) were released from adventitial explants. Smooth muscle cell outgrowth from the media was regulated by endogenous TIMPs, since TIMP inhibition (recombinant MMP-2 or neutralizing anti-TIMP antibodies) facilitated cell outgrowth (P<0.001). In contrast, the addition of recombinant TIMP-1 or -2 decreased adventitial cell outgrowth. In the coculture experiments, the presence of coronary media retarded adventitial cell outgrowth, whereas medial damage abrogated these effects, allowing for fibroblast migration (P<0.001). In conclusion, this study demonstrated differential migratory properties and distinct MMP/TIMP synthesis by coronary fibroblasts and smooth muscle cells. Endogenous TIMPs in the media may play an important role in maintaining coronary arterial wall homeostasis, whereas high levels of matrix-degrading activities confer the "invasive" characteristics of adventitial fibroblasts.

Sustained reduction of neointima with c-myc antisense oligonucleotides in saphenous vein grafts

BACKGROUND

Treatment of saphenous veins with c-myc antisense oligomers during preparation for grafting reduces medial cellular proliferation and macrophage infiltration, and preserves medial smooth muscle content at 3 days. Accordingly, the purpose of this study was to examine whether c-myc antisense oligomers have an impact on late vein graft remodeling.

METHODS

Sixty-two pigs underwent unilateral saphenous vein-carotid artery interposition grafting. Harvested veins were incubated either in saline (control group) or 20-micromol/L or 200-micromol/L concentrations of c-myc antisense oligomers (treated groups) for 30 minutes intraoperatively. Three months after surgery, vein graft histology was assessed.

RESULTS

Forty-five of 62 randomized animals survived the experiment; no differences in animal survival or graft patency among the groups were observed (p = NS, chi2). C-myc antisense oligomers significantly decreased neointimal and wall thickness, as well as increased lumenal index, in treated groups (p<0.04, p<0.03, and p<0.001, respectively, analysis of variance). In contrast, there was no difference in medial thickness or perivascular wound healing.

CONCLUSION

Intraoperative treatment of saphenous veins with c-myc antisense oligomers decreased neointimal formation at 3 months after grafting. In conjunction with our previous reports, these findings suggest that early inhibition of cellular proliferation and inflammatory infiltration results in a sustained reduction in neointimal formation and favorable graft remodeling.

Early injury to the media after saphenous vein grafting

BACKGROUND

Injury to the smooth muscle cells of the media affects the remodeling process of vein grafts. The purpose of this study was to determine whether different techniques of surgical preparation influence the degree of medial smooth muscle injury.

METHODS

Carotid-saphenous vein interposition grafting was performed in crossbred pigs (n = 32), using distended (n = 16) or nondistended (n = 16) conduits. After 3 to 90 days, the media was evaluated for the presence of smooth muscle cells (desmin stains), myofibroblast formation (transient alpha-SM actin expression), and apoptosis (TdT-mediated dUTP nick end-labeling [TUNEL]).

RESULTS

Smooth muscle loss was uniformly severe; only 5% +/- 5% (p < 0.01) and 14% +/- 9% (p < 0.01) of the medial area of distended and nondistended veins were desmin positive in comparison with 80% +/- 9% of controls. Apoptosis appeared to contribute to medial smooth muscle loss (5.7% +/- 4.3% in vein grafts versus 0.0% +/- 0.0% of TUNEL-positive cells in controls; p = 0.05). There was a time dependent increase in medial myofibroblast formation (p < 0.05).

CONCLUSIONS

Severe medial smooth muscle loss occurs in vein grafts, even when prepared without distension. Apoptosis contributes to the early disappearance of smooth muscle cells. Adjunctive measures, in addition to ideal surgical techniques, should be developed to prevent medial muscle loss.

Saphenous vein graft protection: effects of c-myc antisense

OBJECTIVE

Saphenous vein grafting is associated with extensive medial remodeling, characterized by cellular proliferation, loss of smooth muscle cells, and an inflammatory response. In this study, we examined whether unfavorable responses to vein grafting could be modified by the intraoperative application of c-myc antisense oligomers.

METHODS

The intragraft cell proliferation, macrophage infiltration, and medial preservation were examined in a porcine model in the control and antisense-treated groups (n = 36).

RESULTS

Saphenous veins showed transmural distribution of oligomers within 30 minutes of the ex vivo incubation. A concentration-dependent inhibition of cell proliferation in the media of saphenous grafts was noted 3 days later (0 to 200 mumol/L, p = 0.005). The growth inhibition was sequence-specific, because control oligomers produced only insignificant effects (20 mumol/L). Vascular effects of c-myc antisense were associated with a significant attenuation of macrophage infiltration in saphenous grafts. A concentration-dependent decrease in tissue edema (p = 0.0005) and the attenuated loss of smooth muscle cells (p = 0.002) were noted in the media of the arterialized venous conduits after c-myc antisense.

CONCLUSIONS

Direct application of synthetic DNA to harvested saphenous veins resulted in a rapid transmural distribution. The inhibition of the intragraft cell proliferation in vivo after c-myc antisense was sequence dependent. Decrease in vein graft injury resulted in an attenuated inflammatory response and better medial preservation. These findings provide a rationale for assessment of the long-term effects of vein graft protection with c-myc antisense.

Wound healing around and within saphenous vein bypass grafts

BACKGROUND

Myofibroblasts are a prominent cell type in wound healing. The goal of this study was to examine the extent to which myofibroblasts contribute to structural changes in saphenous vein bypass grafts.

METHODS AND RESULTS

Control veins and reversed saphenous vein bypass conduits of porcine carotid arteries were examined 2 to 4, 7 to 14, and 30 to 90 days after surgery with immunohistochemical markers of cellular proliferation (proliferating cell nuclear antigen), cytoskeletal protein production (alpha-smooth muscle actin and desmin), and histochemistry (Verhoeff's stain). Control veins demonstrated an extremely low level of cellular proliferation and no evidence of myofibroblasts in the adventitia, media, or intima. After bypass grafting, cellular proliferation was followed by myofibroblast formation, which occurred in the perivascular area and within the media. This was evidenced by a dense, but transient, expression of alpha-smooth muscle actin and a variable expression of desmin at 1 to 2 weeks, and with a significant increase in collagenous tissue by 1 to 3 months. Major cytoskeletal protein changes also occurred in the intima, with the appearance of alpha-smooth muscle actin positive cells at 7 to 14 days. alpha-Smooth muscle actin was still present in the neointima at 1 to 3 months, which is compatible with a persistent myofibroblast formation.

CONCLUSION

Myofibroblast formation occurs around and within saphenous veins after bypass grafting. This phenomenon is associated with significant remodeling of the vein grafts. The histologic changes are strikingly similar to events that occur during wound healing and may have implications for the development of neointimal hyperplasia and late vein graft disease.

Remodeling of autologous saphenous vein grafts. The role of perivascular myofibroblasts

BACKGROUND

Aortocoronary saphenous vein grafts (SVGs) undergo structural changes that render them susceptible to atherosclerosis. Accordingly, the origin of neointimal hyperplasia-was examined in porcine arterialized SVGs to determine the mechanism of vein graft remodeling.

METHODS AND RESULTS

At 2 to 4 days after surgery, the percentage of cells lacking differentiation markers characteristic for smooth muscle (SM) cells (ie, alpha-SM actin, desmin, and SM myosin) increased within the media of SVGs interposed in the carotid arteries (P < .001). At 7 to 14 days, these cells acquired a differentiated phenotype (ie, alpha-SM-actin positive/ variable desmin/SM-myosin negative) and accumulated in the neointima. At 3 months, the neointima was positive for alpha-SM actin but mostly negative for desmin, which contrasted with medial SMCs that were invariably positive for alpha-SM actin, desmin, and SM myosin. To determine the role of nonmuscle cells in the above process, perivascular wound fibroblasts were selectively labeled and found to translocate through the media of newly placed SVGs, contributing to neointimal formation. These migrating cells differentiated to myofibroblasts exhibiting sustained alpha-SM-actin expression. The intima of human SVGs, retrieved during repeat aortocoronary bypass surgery, exhibited the profile of cytoskeletal proteins that resembled myofibroblasts seen in porcine SVGs.

CONCLUSIONS

Perivascular fibroblasts may infiltrate injured media of arterialized SVGs, differentiate to myofibroblasts (acquiring alpha-SM actin), and contribute to vein graft remodeling. The similarities between porcine and human SVGs regarding the repertoire of cytoskeletal proteins suggest the involvement of myofibroblasts in graft remodeling in the clinical setting.

Vascular myofibroblasts. Lessons from coronary repair and remodeling

Recent findings demonstrate that adventitial fibroblasts (i.e., nonmuscle cells) are endowed with several characteristics previously attributed to medial SM cells. The response of the coronary artery to balloon angioplasty is associated with the activation of adventitial cells in a porcine model. They appear to be the most reactive in the arterial wall, as reflected by the extent of proliferation and the synthesis of collagen. Differentiation of adventitial cells, which acquire alpha-SM actin, illustrates the formation of vascular myofibroblasts, a ubiquitous cellular mechanism of tissue repair. Myofibroblasts are involved in remodeling of the adventitia and may contribute to the formation of the neointima after balloon-induced coronary injury. These findings suggest that at least some synthetic SM-like cells present in intimal lesions may originate from medial or adventitial nonmuscle cells. Myofibroblasts also appear to play a role in other cardiovascular abnormalities (e.g., vein graft remodeling), which raises the possibility of targeted therapies.

Origin of extracellular matrix synthesis during coronary repair

BACKGROUND

Coronary injury triggers differentiation of activated adventitial fibroblasts to myofibroblasts, which may contribute to neointimal formation and vascular remodeling. Accordingly, the purpose of this study was to examine the cellular origin of the enhanced synthesis of extracellular matrix proteins during coronary repair.

METHODS AND RESULTS

The time course and localization of collagen and elastin expression were examined by in situ hybridization and immunohistochemistry in porcine coronary arteries after balloon-induced injury. Procollagen-alpha 1(I) transcripts and intracellular type I procollagen protein increased in the adventitia within 2 days after injury. This was followed by a sustained synthesis of type I procollagen in neointima beginning at 7 days and the extracellular accumulation of type I collagen in both layers. The origin of synthetic cells was further examined by colocalization of type I procollagen and bromodeoxyuridine labeling to activated adventitial cells, which translocated to neointima. Neointimal cells exhibited sustained synthetic activity manifested by the presence of type I procollagen and elastin at 3 months after injury. In contrast, the media showed only minor changes in the synthesis of collagen or elastin throughout coronary repair.

CONCLUSIONS

Activated adventitial fibroblasts are endowed with synthetic capabilities after coronary injury. They express type I procollagen, with some of them translocating to the intima, where they continue to synthesize procollagen. The accumulation of type I collagen is evident in the adventitia and neointima, whereas elastin accumulates mainly in neointima. These findings support the involvement of adventitial fibroblasts in coronary repair and remodeling after endoluminal injury.

Peripheral vascular complications after intracoronary stent placement: prevention by use of a pneumatic vascular compression device

Peripheral vascular complications are a significant source of morbidity after coronary artery stent implantation. The goal of this study was to assess the incidence, risk factors, and management of vascular complications after stent placement. The study population consisted of 101 consecutive patients who underwent stent placement for either elective or bailout indications. All patients received a standardized anticoagulation regimen of aspirin, dipyridamole, low molecular weight dextran, heparin, and warfarin. Peripheral vascular access sites were examined daily until hospital discharge. Vascular complications occurred in 16 of 101 (16%) patients, including femoral artery pseudoaneurysm (n = 11), hematoma requiring transfusion or surgery (n = 4), and arteriovenous fistula (n = 1). Intervention was required in 14 of 16 (88%) patients with complications. These included transfusion (n = 7), ultrasound-guided compression (n = 8), and/or vascular surgery (n = 7). Length of hospital stay was prolonged in patients with complications (14 +/- 9 vs. 8 +/- 5 d, P < 0.001). The development of peripheral vascular complications did not correlate with clinical or procedural variables such as age, cardiovascular risk factors, arterial sheath size, or elective vs. bailout indication. After the introduction of a pneumatic vascular compression device (FEMOSTOP, C.A. Bard, Billerica, MA), a significant reduction in vascular complications was observed. Complications occurred in only 1 of 41 (2.4%) patients in whom the compression device was used in contrast to 13 of 58 (22.4%) patients compressed manually (P < 0.01). Thus peripheral vascular complications are frequent after coronary artery stent placement and are associated with serious morbidity and prolongation of hospital stay. These complications are significantly reduced by the use of a pneumatic vascular compression device despite intensive systemic anticoagulation.

Transforming growth factor-beta 1 expression and myofibroblast formation during arterial repair

Transforming growth factor-beta 1 (TGF-beta 1) plays a central role in tissue repair owing to its modulating effects on cell growth and the synthesis of extracellular matrix. We have previously shown that adventitial fibroblasts differentiate to myofibroblasts after endoluminal injury, thereby contributing to arterial remodeling. Since TGF-beta 1 exerts several biologic actions attributed to myofibroblasts, we examined its role in myofibroblast formation in a porcine model of balloon overstretch coronary artery injury. TGF-beta 1 transcripts were induced in numerous adventitial cells 2 days after injury (47 +/- 10%, P < .001 versus control). These cells displayed no smooth muscle (SM) markers, i.e., alpha-SM actin or desmin, which suggested their fibroblastic origin. This was further corroborated by the rare presence of macrophages in the injured adventitia (3 +/- 1%). At 7 to 8 days, most TGF-beta 1-expressing cells demonstrated alpha-SM actin immunoreactivity. Their myofibroblast phenotype was confirmed by electron microscopy, which revealed microfilaments (stress fibers) and a well-developed rough endoplasmic reticulum. The distribution of TGF-beta 1 transcripts by in situ hybridization was paralleled by the immunolocalization of intracellular and extracellular TGF-beta 1 epitopes. At later times (> 14 days after injury), the decrease in TGF-beta 1 coincided with the disappearance of adventitial myofibroblasts, whereas the neointima exhibited longer TGF-beta 1 expression. In conclusion temporal and spatial relationships between TGF-beta 1 and myofibroblast formation suggest an important role for autocrine TGF-beta 1 in the phenotypic modulation of vascular fibroblasts. Induction of TGF-beta 1 expression may provide a differentiation signal for adventitial fibroblasts to become myofibroblasts, which affect arterial remodeling via their mechanical and synthetic properties.

Adventitial myofibroblasts contribute to neointimal formation in injured porcine coronary arteries

BACKGROUND

The adventitia undergoes remodeling changes after a deep medial coronary injury. Because this process is associated with the formation of adventitial myofibroblasts, which resemble medial smooth muscle (SM) cells, we have examined myofibroblast involvement in the development of neointima.

METHODS AND RESULTS

In a porcine model, severe endoluminal coronary injury resulted in fibroblast proliferation and adventitial remodeling. Significant adventitial responses were associated with increased neointimal formation (P < .01). To examine the contribution of adventitial cells to the development of neointima, proliferating cells were labeled with bromodeoxyuridine (BrdU) at 12 and 24 hours after injury, and their subsequent localization was determined by immunohistochemistry (n = 24). At 2 to 3 days after severe injury, the adventitia contained numerous BrdU-labeled cells (37 +/- 4%), whereas the media demonstrated infrequent labeled cells (4 +/- 1%). Adventitial cells lacked alpha-SM actin and desmin, which distinguished them from medial SM cells. At 7 to 8 days, some labeled cells acquired characteristics of myofibroblasts expressing alpha-SM actin. They were found to translocate to the gap between dissected media and contributed to the formation of neointima (76 +/- 19%). At 18 to 35 days, labeled cells were abundant in the neointima (86 +/- 5%). They showed uniform immunostaining for alpha-SM actin but not for desmin, thereby differing from medial SM cells and blood-borne cells.

CONCLUSIONS

This study demonstrates translocation of adventitial fibroblasts to neointima, their phenotypic modulation to myofibroblasts, and distinct characteristics of myofibroblasts within neointima after severe endoluminal coronary injury. These findings suggest the significance of vascular fibroblasts in the process of arterial repair.

Host nerve fibers that regenerate and reside long-term in a rejected nerve allograft are not protected by permability barriers

We investigated whether permeability barriers develop and protect host nerve fibers that regenerate and reside long-term in a rejected nerve allograft. In order for the barriers to form, host cells have to enter the rejected allograft and differentiate into new endothelial and perineurial cells that respectively form the impermeable endoneurial blood-nerve and the perineurium-nerve barriers that are present in normal nerve. A 2-cm long graft of peroneal nerve was taken from American Cancer Institute (ACI) or Fischer (FR) rats and transplanted to bridge a 2-cm gap between the cut ends of the peroneal nerve of other FR rats. Six months postoperatively, histology revealed that regenerated host nerve fibers in ACI allografts were compartmentalized into numerous minifascicles by perineurial cells and that blood vessels were located outside rather than inside the perineurial compartments among the nerve fibers. Administration of the permeability indicator horseradish peroxidase to allograft recipients (intravenously or topically to the graft in situ) revealed that it entered the endoneurium of microcompartments and spread around the nerve fibers. In contrast, none of the indicator reached nerve fibers in FR syngrafts or normal ACI or FR nerves which were not microcompartmentalized. We concluded that host nerve fibers that regenerate and reside long-term in a rejected nerve allograft are not protected by permeability barriers.

Adventitial remodeling after coronary arterial injury

BACKGROUND

Intraluminal thrombus formation and medial smooth muscle (SM) cell proliferation are recognized responses of the arterial system to injury. In contrast to these well-characterized processes during vascular repair, changes involving the adventitia have been largely neglected in previous studies. Hence, the goal of this investigation was to assess the response of the adventitia to coronary arterial injury.

METHODS AND RESULTS

Adventitial changes in porcine coronary arteries subjected to medial injury were characterized by immunohistochemistry, histochemistry, and microscopic morphometry. The rapid development of a hypercellular response in the adventitia was evident 3 days after balloon-induced medial injury. Cell proliferation, as assessed by proliferating cell nuclear antigen immunostaining, reached the maximum level in the adventitia at 3 days, whereas at 14 and 28 days, the number of replicating cells reverted toward the baseline. The proliferating activity in the adventitia exceeded that seen in the media at all times after injury. To further define the changes in the phenotype of adventitial cells, the expression of three cytoskeletal proteins (vimentin, alpha-SM actin, and desmin) was characterized. Fibroblasts in normal adventitia expressed vimentin but no alpha-SM actin or desmin. After injury, these cells acquired characteristics of myofibroblasts expressing alpha-SM actin, which peaked at 7 and 14 days. Desmin expression was patchy in the adventitia, as opposed to its homogeneous distribution in medial SM cells. The modulation of fibroblast phenotype was transient, inasmuch as alpha-SM actin immunostaining declined at 28 days after injury, when dense, collagen-rich scar was evident within the adventitia. The above-described changes involving hypercellularity of the adventitia, myofibroblast formation, and fibrosis were associated with a significant focal adventitial thickening at 3, 7, 14, and 28 days after injury (P < .01 versus uninjured coronary arteries).

CONCLUSIONS

This study demonstrates the involvement of the adventitia in the vascular repair process after medial injury. The hypercellularity of the adventitial layer, proliferation of fibroblasts, and modulation of their phenotype to myofibroblasts are associated with the development of the thickened adventitia. It is postulated that these phenomena affect vascular remodeling and may provide an important insight into the mechanisms of vascular disorders.

Transgene expression in the coronary circulation: transcatheter gene delivery

Therapeutic and research applications of direct gene transfer in the coronary vasculature are limited by varying transgene activity found in the vessel wall. It remains to be determined whether this is due to difficulties in delivery of recombinant DNA into the coronary arteries or if it relates to the state of recipient cells in the arterial wall. Accordingly, using a clinically applicable protocol, we have examined the time course of transgene (luciferase) expression in porcine coronary vasculature following transcatheter gene transfer (1 day to 4 weeks). Liposome-mediated transfection by means of a transcatheter approach resulted in detectable luciferase activity in all transfected vessels at 1 day after gene delivery. However, the activity of a reporter gene rapidly declined at 7 days thereafter, with only 33% of coronary arteries demonstrating luciferase activity. Comparable levels of transgene sequences were present in transfected vessels, although no correlation with luciferase activity was found. To further determine possible mechanisms responsible for rapidly declining transgene expression in vivo, cell proliferation was induced in the vessel wall by means of either balloon denudation or by intramural injections of platelet derived growth factor BB (PDGF-BB) into the porcine coronary vasculature at the time of gene transfer. Luciferase activity was significantly augmented (23-fold) following mitogenic stimulation in vivo as compared with the control transfected coronary arteries. These data demonstrate that a practical transcatheter approach provides an effective route to deliver recombinant DNA sequences into the coronary arterial wall.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of coronary angiographic findings during the first six hours of non-Q-wave and Q-wave myocardial infarction

The angiographic features of non-Q-wave acute myocardial infarction (AMI) soon after symptom onset have not been previously reported. Accordingly, this study reviewed the coronary angiographic findings of 86 patients with AMI studied within 6 hours of symptom onset: 58 had Q-wave and 28 had non-Q-wave AMI. Patients with Q-wave and non-Q-wave AMI were comparable in terms of clinical characteristics, frequency of 1-vessel disease, and infarct-related artery location. Thrombus was observed in 49 patients (84%) with Q-wave AMI versus 12 (43%) with non-Q-wave AMI (p = 0.0002). Whereas complete occlusion of the infarct-related artery was present in 53 patients (91%) with Q-wave AMI, total coronary occlusion was present in only 11 (39%) with non-Q-wave AMI (p = 0.0001). Collaterals to occluded infarct arteries were seen in 10 patients (19%) with Q-wave AMI versus 5 (45%) with non-Q-wave AMI (p = 0.06). Residual perfusion of the infarct artery by either anterograde or collateral flow was typical of patients with non-Q-wave AMI (22 of 28, 79%) but was uncommon in those with Q-wave AMI (15 of 58, 26%) (p = 0.0001). Thus, coronary angiography performed within 6 hours of symptom onset demonstrates important differences between Q-wave and non-Q-wave AMI. Non-Q-wave AMI is characterized by partial perfusion of the infarct-related artery by either anterograde or collateral flow, and a lower incidence of thrombus than Q-wave AMI.(ABSTRACT TRUNCATED AT 250 WORDS)

Transcatheter delivery of c-myc antisense oligomers reduces neointimal formation in a porcine model of coronary artery balloon injury

BACKGROUND

Smooth muscle cell proliferation and extracellular matrix accumulation are the principal mechanisms leading to vascular restenosis. We have previously demonstrated the growth-inhibitory effect of antisense oligomers targeting the c-myc proto-oncogene in human smooth muscle cells. The goal of this study was to investigate whether c-myc antisense oligomers reduce neointimal formation in balloon-denuded porcine coronary arteries.

METHODS AND RESULTS

First, type I collagen synthesis, which reflects synthetic function, was markedly reduced following c-myc antisense oligomers in porcine vascular smooth muscle cells independent of the growth inhibition. These effects in vitro provided the rationale for assessing c-myc antisense oligomers in the prevention of neointima in vivo. Second, the efficiency of single transcatheter delivery of oligomers into denuded porcine coronary arteries was determined. Despite rapid plasma clearance following local delivery, oligomers persisted at the site of injection for at least 3 days, exceeding by severalfold their concentration in peripheral organs. Third, morphometric analyses were carried out in balloon-denuded coronary arteries at 1 month after transcatheter c-myc antisense oligomer administration. Maximal neointimal area was reduced from 0.80 +/- 0.17 mm2 in the control group (n = 12) to 0.24 +/- 0.06 mm2 in the antisense-treated group (n = 13, P < .01). Likewise, a significant reduction in maximal neointimal thickness was observed in the antisense-treated group (P < .01). These changes in vascular remodeling following denuding injury resulted in an increase in residual lumen from 64 +/- 6% in the control group to 81 +/- 5% in the antisense-treated group (P < .05).

CONCLUSIONS

(1) Single transcatheter administration allowed for endoluminal delivery of oligomers to the site of coronary arterial injury. (2) C-myc antisense oligomers reduced the formation of neointima in denuded coronary arteries, implying a therapeutic potential of this approach for the prevention of coronary restenosis. (3) It is postulated that the c-myc proto-oncogene is involved in the process of vascular remodeling, regulating smooth muscle cell proliferation and extracellular matrix synthesis.

Downregulation of c-myc expression by antisense oligonucleotides inhibits proliferation of human smooth muscle cells

BACKGROUND

Proliferation of smooth muscle cells (SMCs) plays an important role in vascular pathobiology, being involved in the development of coronary restenosis and atherosclerosis. The activation of nuclear proto-oncogenes appears to be a final common pathway onto which various mitogenic signals coverage. Accordingly, we attempted to determine whether the activation of the c-myc nuclear proto-oncogene is essential for human SMC proliferation and explored the possibility of inhibiting their growth using antisense oligonucleotides directed against c-myc messenger RNA (mRNA).

METHODS AND RESULTS

Proliferation of human SMCs was associated with an increase in c-myc mRNA expression after growth stimulation. Using 15-mer phosphorothioate oligonucleotides (oligomers), we tested their growth-inhibitory effect in SMCs in vitro. Antisense oligomers directed against the translation initiation region of the human c-myc gene exhibited a significant antiproliferative effect, whereas sense and mismatched oligomers did not inhibit the growth. The growth-inhibitory effect of c-myc antisense oligomers was dose dependent and preventable by an excess of sense oligomers. Furthermore, growth inhibition of SMCs treated with c-myc antisense oligomers was associated with a marked decrease in the c-myc mRNA level. Phosphorothioate oligomers remained stable in medium containing 20% serum and were detectable in SMCs as early as 1 hour after cell exposure. Intact oligomers rapidly accumulated intracellularly and persisted within human SMCs for at least 16 hours.

CONCLUSIONS

c-myc antisense oligomers reduced c-myc expression and produced a significant growth inhibition of human SMCs, indicating an important role of c-myc gene activation in the process of SMC proliferation. Furthermore, extracellular stability and rapid cellular uptake provide the basis for future studies assessing the therapeutic role of the c-myc antisense approach in reducing SMC proliferation in the process of vascular restenosis.

Selective dopamine-1 receptor agonist augments regional myocardial blood flow: Comparison of fenoldopam and dopamine

A new class of vasodilators exhibiting selective dopamine-1 receptor agonist activity is being introduced into clinical practice. Inasmuch as various vasodilators either augment or decrease myocardial blood flow ("coronary steal") depending on their pharmacologic action, the goal of this study was to assess the effects of fenoldopam (selective dopamine-1 receptor agonist) and dopamine (nonselective dopamine-1 receptor agonist) on regional myocardial blood flow in the presence of coronary occlusion. Accordingly, in 16 dogs anesthetized with pentobarbital, the left anterior descending coronary artery was occluded. Cardiovascular and renal hemodynamic effects were measured before and after intravenous infusion of renal equipotent doses of either fenoldopam (n = 9, 0.1 micrograms/kg/min) or dopamine (n = 7, 1 micrograms/kg/min). Both fenoldopam and dopamine caused a significant and comparable increase in renal blood flow. Fenoldopam but not dopamine significantly decreased the calculated peripheral vascular resistance and subsequently increased cardiac output. Dopamine had no effect on regional myocardial blood flow. In contrast, fenoldopam augmented transmural myocardial blood flow in normal (from 114 +/- 10 to 188 +/- 27 ml/100 gm/min, p less than 0.02) and ischemic border myocardium (from 45 +/- 5 to 68 +/- 11 ml/100 gm/min, p less than 0.03 and p less than 0.02 vs dopamine). There was a significant increase in blood flow to both the endocardial and epicardial layers of normal and ischemic border myocardium. These changes were accompanied by a significant reduction in coronary vascular resistance in the normal myocardium.(ABSTRACT TRUNCATED AT 250 WORDS)

Fibrinolytic activity after vessel wall injury

The goal of this study was to assess fibrinolytic activity after vessel wall injury and to correlate changes in fibrinolytic activity with angiographic and histologic findings. Accordingly, in 18 atherosclerotic rabbits, vessel wall injury was produced by means of iliac artery balloon angioplasty (the injury group), whereas 8 atherosclerotic rabbits served as a control group. In all rabbits from the injury group, deep vessel wall injury was documented by either angiography or histologic study. Plasminogen activator inhibitor-1 activity in plasma increased significantly, from 21.79 +/- 1.29 arbitrary units/ml (AU/ml) at baseline study to 32.05 +/- 1.47 AU/ml at 6 h after vessel wall injury (p less than 0.01), whereas activity remained unchanged throughout the 24-h period in the control group. Plasma levels of tissue plasminogen activator activity were similar in both groups. Intravascular thrombus was found in five of six additional rabbits 6 h after vessel wall injury, that is, at the time of impaired fibrinolytic activity, whereas no thrombus was found in the control group (p less than 0.05). It is concluded that deep vessel wall injury is associated with reduced fibrinolytic activity. In addition to other procoagulant factors, elevated plasminogen activator inhibitor-1 activity may lead to intravascular thrombosis and impaired resolution of thrombus.

Evidence for reduced fibrinolytic activity in unstable angina at rest. Clinical, biochemical, and angiographic correlates

BACKGROUND

The goal of this study was to evaluate the role of the fibrinolytic system in patients with unstable angina at rest associated with transient electrocardiographic changes.

METHODS AND RESULTS

Tissue plasminogen activator activity in plasma was comparable among patients with unstable angina (n = 17), patients with stable exertional angina (n = 10), and control patients with normal coronary arteriograms (n = 8). In contrast, plasminogen activator inhibitor-1 (PAI-1) activity in plasma was elevated in the unstable angina group (21.67 +/- 9.52 AU/ml) as compared with either the stable angina group (12.01 +/- 7.06 AU/ml, p less than 0.02) or the controls (12.49 +/- 8.54 AU/ml, p less than 0.02). Coronary angiography performed within 24 hours after the last anginal episode showed a similar extent of coronary artery disease in the unstable and stable angina groups. However, intracoronary thrombi were observed in eight patients in the unstable angina group while no thrombus was noted in the stable angina group (chi 2 = 7.22, p less than 0.01).

CONCLUSIONS

We conclude that patients with unstable angina at rest have a reduced fibrinolytic activity and an increased incidence of intracoronary thrombi. It is postulated that elevated PAI-1 activity in the presence of coronary arterial wall injury may be an important factor leading to the development of acute coronary syndromes.