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Biomedical subjects

Walter J Koch

Publications and source records attributed to Walter J Koch.

At least 37 records · Page 2Linked to original sources
PubMed2005

Acute ischemic cardiac dysfunction is attenuated via gene transfer of a peptide inhibitor of the beta-adrenergic receptor kinase (betaARK1).

Acute myocardial ischemia is a critical adverse effect potentially occurring during cardiac procedures. A peptide inhibitor of the beta-adrenergic receptor kinase (betaARK1), betaARKct, has been successful in rescuing chronic myocardial ischemia. The present study focused on the effects of adenoviral-mediated betaARKct (Adv-betaARKct) delivery on left ventricle (LV) dysfunction induced by acute coronary occlusion. Rabbits received intracoronary delivery of phosphate-buffered saline (PBS) (n=9) or 5x10(11) viral particles of betaARKct (n=8). A loose prolene 5-0 Potz-loop suture was placed around the circumflex coronary artery (LCx) with both ends buried under the skin. Four days later, the suture was retrieved and pulled to occlude the LCx. Ischemia was confirmed by immediate ECG changes. LV function was continuously recorded for 45 min. Contractility (LVdP/dtmax), relaxation (LVdP/dtmin) and end diastolic pressure (EDP) were less impaired in the betaARKct group as compared to PBS (P<0.05, two-way ANOVA). betaAR density was higher in the ischemic area of the LV in the betaARKct group (betaARKct: 71.9+/-4.6 fmol/mg protein, PBS: 54.5+/-4.0 fmol/mg protein, P<0.05). Adenylyl cyclase activity was also improved basally and in response to betaAR stimulation. betaARK1 activation was less in the betaARKct group (P<0.05). Therefore, inhibition of myocardial betaARK1 may represent a new strategy to prevent LV dysfunction induced by acute coronary ischemia.

Adenoviridae↗
PubMed2005

Reduction of vascular intimal-medial hyperplasia in polytetrafluoroethylene arteriovenous grafts via expression of an inhibitor of G protein signaling.

Polytetrafluoroethylene (PTFE) arteriovenous (AV) grafts are performed routinely for vascular access. The limited life span of PTFE grafts is a major cause of morbidity. Graft failure is attributed to venous outflow tract vascular smooth muscle (VSM) hyperplasia, which is linked to heterotrimeric G protein signaling. We proposed that expression of a peptide inhibitor of G(betagamma) signaling (betaARKct) in the venous outflow of PTFE grafts would reduce hyperplasia and prolong graft patency. Left carotid to right external jugular vein PTFE AV grafts were placed in swine. The isolated external jugular vein was treated with an adenovirus encoding betaARKct, empty adenovirus, or phosphate-buffered saline for approximately 25 min. After 7 or 28 days, flow probe analysis was performed and the vein was harvested and analyzed for cross-sectional area comparison. After both 7 and 28 days, when compared to controls, treated animals demonstrated a statistically significant reduction in VSM hyperplasia with a reduction in cross-sectional intimal and medial areas of >40% (p < 0.05). Flow was maintained in treated grafts, while control groups demonstrated a >50% reduction (p < 0.05) at 7 days. Further, treated grafts demonstrated significant improvement in graft patency at 28 days (100% vs. 12% for treated and untreated grafts, respectively). The inhibition of G(betagamma) signaling reduces intimal-medial hyperplasia and prolongs graft patency in PTFE AV grafts. This represents a novel molecular therapeutic strategy for improving the patency of vascular access grafts.

Anatomy, Cross-Sectional↗
PubMed2005

A Gbetagamma inhibitor reduces intimal hyperplasia in aortocoronary saphenous vein grafts.

OBJECTIVE: Approximately 50% of aortocoronary saphenous vein grafts are occluded 10 years after coronary revascularization surgery. Intimal hyperplasia, a critical component in saphenous vein graft failure, is defined by vascular smooth muscle cell proliferation, which is mediated in part by betagamma subunits of heterotrimeric G proteins (G(betagamma)) and downstream effectors such as mitogen-activated protein kinases. A peptide consisting of the carboxyl-terminus of the beta-adrenergic receptor kinase (betaARKct) binds G(betagamma), thereby inhibiting G(betagamma) signaling. Utilizing a recombinant adenovirus containing the coding sequence for the betaARKct peptide (AdbetaARKct), this study investigates whether treatment of the vein graft with AdbetaARKct reduces intimal hyperplasia in a large animal model of aortocoronary saphenous vein graft intimal hyperplasia. METHODS: Twenty-seven dogs (27-32 kg) underwent aortocoronary bypass grafting to the left anterior descending artery using autologous saphenous vein. Vein grafts were treated with saline (n = 8), an empty adenovirus (n = 8), or AdbetaARKct (n = 8). A subset of dogs (n = 3) were sacrificed on postoperative day 7 and betaARKct expression confirmed by Northern blotting. RESULTS: Arteriograms performed on postoperative day 90 confirmed that saphenous vein grafts were patent. At postoperative day 90, AdbetaARKct-treated grafts demonstrated reduced intimal area compared to empty virus and saline treated animals (P < .05). Additionally, AdbetaARKct treatment of isolated vascular smooth muscle cells in vitro inhibited mitogen-activated protein kinase activation and decreased overall vascular smooth muscle cell proliferation. CONCLUSION: This study demonstrates that betaARKct expression in aortocoronary saphenous vein grafts reduces intimal hyperplasia and decreases vascular smooth muscle cell proliferation in vitro via inhibition of G(betagamma)-mediated mitogen-activated protein kinase activation. Modulation of G(betagamma) via betaARKct may represent a novel therapy to reduce intimal hyperplasia and saphenous vein graft failure.

Animals↗
PubMed2005

Gene therapy approaches to cardiovascular disease.

The potential of enhanced cardiovascular function via gene therapy has aroused extensive interest. Both viral and nonviral vectors have shown promise in the realm of cardiovascular gene therapy. Modification of vectors or addition of further transgenes to the expression cassette has permitted targeted and regulated gene expression. The many potential targets of cardiovascular gene therapy can be considered under the following headings: vascular, congenital heart disease, and myocardial. Cardiac gene delivery may be to either the endothelium of either native coronary vessels or coronary artery bypass grafts, or to the myocardium. Myocardial gene delivery is possible either via direct myocardial injection or via the coronary vasculature. However, alteration of any cardiac cellular signaling pathway may have cardiotoxic effects. Thus, any genes that appear to cause enhanced cardiac function, must undergo extensive toxicity studies in animals before similar experiments are performed in human subjects. The techniques described may be utilized in the future to deliver various genes targeted to combat many different disease processes, in different animal models, and ultimately to provide feasible gene therapy approaches to human cardiovascular disease.

Animals↗
PubMed2005

Cardiac gene delivery using DNA-adenoviral constructs.

In view of the limitations of current cardiac gene transfer techniques by direct myocardial injection, or via the coronary vasculature, we have been attempting to develop potentially clinically applicable methods. Selective catheterization of the coronary arteries has been performed, but the duration of exposure of the heart to the virus is limited. Present systems require high infusion pressure to inject the virus, which could result in endothelial or myocardial injury, and extracardiac transgene expression occurs. An alternative method has been developed in which the adenoviral vector is administered following cardioplegic arrest of the heart during cardiopulmonary bypass (CPB), which allows prolonged myocardial contact with the adenoviral vector. This may be advantageous since intracoronary delivery of vector in a Langendorff perfused heart model has shown that prolonged contact time with the virus improves gene transfer. Despite the detrimental effect of cold temperatures and contact with blood on transgene expression in the in vitro and ex vivo studies, we have demonstrated that these factors are unimportant in this in vivo model. Exposure of extracardiac tissues to the vector is limited. Moreover, administration of the beta2AR transgene has resulted in amelioration of impaired cardiac function following CPB and cardioplegic arrest.

Adenoviridae↗
PubMed2004

Role of Omi/HtrA2 in apoptotic cell death after myocardial ischemia and reperfusion.

BACKGROUND: Omi/HtrA2 is a proapoptotic mitochondrial serine protease involved in caspase-dependent as well as caspase-independent cell death. However, the role of Omi/HtrA2 in the apoptotic cell death that occurs in vivo under pathological conditions remains unknown. The present study was designed to investigate whether Omi/HtrA2 plays an important role in postischemic myocardial apoptosis. METHODS AND RESULTS: Male adult mice were subjected to 30 minutes of myocardial ischemia followed by reperfusion and treated with vehicle or ucf-101, a novel and specific Omi/HtrA2 inhibitor, 10 minutes before reperfusion. Myocardial ischemia/reperfusion significantly increased cytosolic Omi/HtrA2 content and markedly increased apoptosis. Treatment with ucf-101 exerted significant cardioprotective effects, as evidenced by less terminal dUTP nick end-labeling staining, a lower incidence of DNA ladder fragmentation, and smaller infarct size. Furthermore, treatment with ucf-101 before reperfusion attenuated X-linked inhibitor of apoptosis protein degradation and inhibited caspase-9 and caspase-3 activities. CONCLUSIONS: Taken together, these results demonstrate for the first time that ischemia/reperfusion results in Omi/HtrA2 translocation from the mitochondria to the cytosol, where it promotes cardiomyocyte apoptosis via a protease activity-dependent, caspase-mediated pathway.

Animals↗
PubMed2004

Cardioprotective effects of thioredoxin in myocardial ischemia and reperfusion: role of S-nitrosation [corrected].

Apoptosis contributes to myocardial ischemia/reperfusion (MI/R) injury, and both thioredoxin (Trx) and nitric oxide have been shown to exert antiapoptotic effects in vitro. Recent evidence suggests that this particular action of Trx requires S-nitrosation at Cys-69. The present study sought to investigate whether or not exogenously applied Trx reduces MI/R injury in vivo and to which extent this effect depends on S-nitrosation. Adult mice were subjected to 30 min of MI and treated with either vehicle or human Trx (hTrx, 2 mg/kg, i.p.) 10 min before reperfusion. Native hTrx was incorporated into myocardial tissue as shown by immunostaining, and reduced MI/R injury as evidenced by decreased terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) staining, DNA fragmentation, caspase-3 activity, and infarct size. When hTrx was partially S-nitrosated by preincubation with S-nitrosoglutathione, its cardioprotective effect was markedly enhanced. Treatment with hTrx significantly reduced p38 mitogen-activated protein kinase (MAPK) activity, and this effect was also potentiated by S-nitrosation. To further address the role of S-nitrosation for the overall antiapoptotic effect to Trx, the action of Escherichia coli Trx (eTrx) was investigated in the same model. Whereas eTrx inhibited MI/R-induced apoptosis to a degree similar to hTrx, S-nitrosation of this protein, which lacks Cys-69, failed to further enhance its antiapoptotic action. Collectively, our results demonstrate that systemically applied Trx is taken up by the myocardium to exert potent cardioprotective effects in vivo, offering interesting therapeutic avenues. In the case of hTrx, these effects are further potentiated by S-nitrosation, but this posttranslational modification is not essential for protection.

Animals↗
PubMed2004

Calcium channel function and regulation in beta 1- and beta 2-adrenoceptor transgenic mice.

Cardiac effects of catecholamines on the L-type calcium channel depend on beta-adrenoceptor subtype (beta(1)- vs. beta(2)-adrenoceptor). Chronic overexpression of these receptors leads to hypertrophy and early death at moderate (beta(1)) or excessive (beta(2)) levels of overexpression respectively. In order to examine the role of L-type calcium channels in altered cardiomyocyte calcium homeostasis found with beta(1)-adrenoceptor overexpression, and to understand the quantitative differences between beta-adrenoceptor subtypes regarding calcium channel regulation, we examined single channels in myocytes obtained from beta(1)- and beta(2)-adrenoceptor transgenic mice. The effects of the agonist isoproterenol were investigated and compared with acute receptor stimulation in the respective non-transgenic littermates. Channels from beta(1)-adrenoceptor transgenic mice have normal baseline activity, and channel number is not reduced. This contrasts to previous findings with beta(2)-adrenoceptor transgenic mice, where channel activity is depressed. Isoproterenol is unable to stimulate channel activity in both transgenic models. In conclusion, the L-type calcium channel is not likely to be involved in alterations of calcium handling of beta(1)-adrenoceptor transgenic myocytes. Furthermore, chronic beta(1)-adrenoceptor overexpression does not depress channel activity, giving another example of the difference between beta(1)- and beta(2)-adrenoceptor signal transduction.

Adrenergic beta-Agonists↗
PubMed2004

Targeted beta-adrenergic receptor kinase (betaARK1) inhibition by gene transfer in failing human hearts.

BACKGROUND: Failing human myocardium is characterized by an attenuated contractile response to beta-adrenergic receptor (betaAR) stimulation due to changes in this signaling cascade, including increased expression and activity of the beta-adrenergic receptor kinase (betaARK1). This leads to desensitization and downregulation of betaARs. Previously, expression of a peptide inhibitor of betaARK1 (betaARKct) has proven beneficial in several animal models of heart failure (HF). METHODS AND RESULTS: To test the hypothesis that inhibition of betaARK1 could improve beta-adrenergic signaling and contractile function in failing human myocytes, the betaARKct was expressed via adenovirus-mediated (AdbetaARKct) gene transfer in ventricular myocytes isolated from hearts explanted from 10 patients with end-stage HF undergoing cardiac transplantation. AdbetaARKct also contained the marker gene, green fluorescent protein, and successful gene transfer was confirmed via fluorescence and immunoblotting. Compared with uninfected failing myocytes (control), the velocities of both contraction and relaxation in the AdbetaARKct-treated cells were increased in response to the beta-agonist isoproterenol (contraction: 57.5+/-6.6% versus 37.0+/-4.2% shortening per second, P<0.05; relaxation: 43.8+/-5.5% versus 27.5+/-3.9% lengthening per second, P<0.05). Fractional shortening was similarly enhanced (12.2+/-1.2% versus 8.0+/-0.9%, P<0.05). Finally, adenylyl cyclase activity in response to isoproterenol was also increased in AdbetaARKct-treated myocytes. CONCLUSIONS: These results demonstrate that as in animal models of HF, expression of the betaARKct can improve contractile function and beta-adrenergic responsiveness in failing human myocytes. Thus, betaARK1 inhibition may represent a therapeutic strategy for human HF.

Adenoviridae↗
PubMed2004

G protein-coupled receptor internalization signaling is required for cardioprotection in ischemic preconditioning.

The present study is designed to explore the role of G protein-coupled receptors (GPCRs) in the protection afforded by ischemic preconditioning (PC). We used TG mice with cardiac-specific overexpression of a Gbetagamma-sequestering peptide, betaARKct (TG betaARKct mice), to test whether the protection of PC is Gbetagamma-dependent. To test the role of G(i) protein, we used wild-type mice pretreated with the G(i) inhibitor pertussis toxin. Recovery of left ventricular developed pressure and infarct size were measured as indices of protection. PC induced protection in wild-type mice, but this protection was blocked by pertussis toxin treatment and was also blocked in TG betaARKct mice. To determine the mechanism of Gbetagamma-induced protection in PC, we investigated one of the downstream targets of Gbetagamma, the PI3K/p70S6K pathway. PC-induced phosphorylation of p70S6K was not blocked in TG betaARKct hearts; therefore, we investigated other targets of Gbetagamma. Recent studies suggest a role for Gbetagamma in GPCR internalization. We found that betaARKct, a specific PI3K inhibitor wortmannin, and bafilomycin A1, which all block receptor recycling, all blocked the protective effect of PC. To additionally test whether PI3K is involved in PC-activated receptor internalization and endosomal signaling, we used TG mice with cardiac-specific overexpression of a catalytically inactive mutant PI3Kgamma, which disrupts the recruitment of functional PI3K to agonist-activated GPCRs in vivo. We found that the catalytically inactive mutant of PI3Kgamma blocks the protection of PC. In summary, these data suggest the novel finding that the cardioprotective effect of PC requires receptor internalization.

Androstadienes↗
PubMed2004

Cardioprotective effects of erythropoietin in the reperfused ischemic heart: a potential role for cardiac fibroblasts.

Erythropoietin has recently been shown to have effects beyond hematopoiesis such as prevention of neuronal and cardiac apoptosis secondary to ischemia. In this study, we evaluated the in vivo protective potential of erythropoietin in the reperfused rabbit heart following ventricular ischemia. We show that "preconditioning" with erythropoietin activates cell survival pathways in myocardial tissue in vivo and adult rabbit cardiac fibroblasts in vitro. These pathways, activated by erythropoietin in both whole hearts and cardiac fibroblasts, are also activated acutely by ischemia/reperfusion injury. Moreover, in vivo studies indicate that erythropoietin treatment either prior to or during ischemia significantly enhances cardiac function and recovery, including left ventricular contractility, following myocardial ischemia/reperfusion. Our data indicate that a contributing in vivo cellular mechanism of this protection is mitigation of myocardial cell apoptosis. This results in decreased infarct size as evidenced by area at risk studies following in vivo ischemia/reperfusion injury, translating into more viable myocardium and less ventricular dysfunction. Therefore, erythropoietin treatment may offer novel protection against ischemic heart disease and may act, at least in part, by direct action on cardiac fibroblasts and myocytes to alter survival and ventricular remodeling.

Animals↗
PubMed2004

S100A1 gene transfer: a strategy to strengthen engineered cardiac grafts.

BACKGROUND: Cardiac tissue replacement therapy, although a promising novel approach for the potential treatment of heart failure, still suffers from insufficient contractile support to the failing myocardium. Here, we explore a strategy to improve contractile properties of engineered heart tissue (EHT) by S100A1 gene transfer. METHODS: EHTs were generated from neonatal rat cardiomyocytes and transfected (MOI 10 PFU) with the S100A1 adenovirus (AdvS100A1, n = 25) while an adenovirus devoid of the S100A1 cDNA served as a control (AdvGFP, n = 30). Contractile properties of transfected EHTs were measured 7 days following gene transfer. RESULTS: Western blot analysis confirmed a 8.7 +/- 3.6-fold S100A1 protein overexpression in AdvS100A1-transfected EHTs (n = 4; P < 0.01) that increased maximal isometric force (mN; AdvGFP 0.175 +/- 0.03 vs. AdvS100A1 0.47 +/- 0.06; P < 0.05) at 0.4 mmol/L extracellular calcium concentration [Ca(2+)](e). In addition, S100A1 overexpression enhanced both maximal Ca(2+)-stimulated force generation (+81%; P < 0.05) and Ca(2+)-sensitivity of EHTs (EC50% [Ca(2+)](e) mM; AdvGFP 0.33 +/- 0.04 vs. AdvS100A1 0.21 +/- 0.0022; P < 0.05). The S100A1-mediated gain in basal graft contractility was preserved throughout a series of isoproterenol interventions (10(-9) to 10(-6) M). Physiological properties of EHTs resembling intact heart preparations were preserved. CONCLUSIONS: S100A1 gene transfer in EHT is feasible and augments contractile performance, while characteristic physiological features of EHT remain unchanged. Thus, specific genetic manipulation of tissue constructs prior to implantation should be part of an improved tissue replacement strategy in heart failure.

Adenoviridae↗
PubMed2004

Catheter-mediated delivery of adenoviral vectors expressing beta-adrenergic receptor kinase C-terminus inhibits intimal hyperplasia and luminal stenosis in rabbit iliac arteries.

BACKGROUND: Previous studies have shown that incubation of balloon-injured rat carotid arteries with adenoviral vectors encoding the carboxyl terminus of the beta-adrenergic receptor kinase (Ad2/betaARKct) for 30 min reduces neointima formation. However, it is unclear whether this beneficial effect of betaARKct could be achieved using a catheter-based vector delivery system and whether the observed inhibition of neointima formation translated into a reduction of vessel stenosis. METHODS: In this study, Ad2/betaARKct was infused into the balloon-injured site of rabbit iliac arteries using a porous infusion catheter over 2 min. Twenty-eight days after gene transfer, angiographic and histological assessments were performed. RESULTS: Angiographic and histological assessments indicate significant (p < 0.05) inhibition of iliac artery neointima formation and lumen stenosis by Ad2/betaARKct. Our studies demonstrate that an inhibitory effect of Ad2/betaARKct on neointima formation is achievable using a catheter-based vector delivery system and that the inhibition of neointima formation translates into a gain in the vessel minimal luminal diameter. The extent of inhibition (35%) was comparable to that observed with adenoviral-mediated expression of thymidine kinase plus ganciclovir treatment, a cytotoxic gene therapy approach for restenosis. CONCLUSIONS: These results suggest that adenoviral-mediated gene transfer of betaARKct is a clinically viable cytostatic gene therapy strategy for the treatment of restenosis.

Adenoviridae↗
PubMed2004

beta2 adrenoceptor gene therapy ameliorates left ventricular dysfunction following cardiac surgery.

OBJECTIVE: Heart surgery is associated with impairment of the myocardial beta-adrenoceptor (betaAR) system. Effective therapies for post-operative ventricular dysfunction are limited. Prolonged inotrope exposure is associated with further betaAR down-regulation. Left ventricular (LV) dysfunction and myocardial betaAR impairment were assessed following cardiopulmonary bypass (CPB) and cardioplegic arrest in a pig model. Transfer of the human beta2-adrenoceptor transgene (Adeno-beta2AR) during cardioplegic arrest was then tested as a potential therapy. METHODS: Five groups of six neonatal piglets were studied. One group did not undergo surgery (Group A). Adeno-beta2AR or phosphate buffered saline (PBS) were delivered via the aortic root during cardioplegic arrest. Groups B (PBS) and C (Adeno-beta2AR) were assessed at 2 days while Groups D (PBS) and E (Adeno-beta2AR) were assessed at 2 weeks from the time of surgery. An LV micromanometer was inserted under sedation to obtain pressure recordings following surgery. betaAR density was measured subsequently. RESULTS: Following cardiac surgery LV betaAR density was reduced (104+/-5.7 vs 135+/-6.1 fmol/mg membrane protein; P=0.007), and, in response to beta agonist stimulation, LV dP/dtmax was reduced (4337+/-405 vs 5328+/-194 mmHg/s; P<0.05) compared to animals which did not undergo surgery. Adeno-beta2AR therapy during cardiac surgery resulted in elevated LV betaAR density (520+/-250.9 fmol/mg) 2 days post-operatively compared to PBS (104+/-5.7 fmol/mg; P=0.002) and compared to the no surgery group (135+/-6.1 fmol/mg; P=0.002). Elevated LV betaAR density was also present at 2 weeks (315+/-74.1 vs 119+/-7.1 fmol/mg; P=0.002). In addition, Adeno-beta2AR therapy enhanced beta agonist stimulated LV dP/dtmax (5348+/-121 vs 4337+/-405 mmHg/s; P<0.05) and heart rate (209+/-6.9 vs 173+/-11.0 bpm; P<0.05), and reduced LVEDP (2.1+/-0.4 vs 6.4+/-1.8 mmHg; P<0.05) compared to PBS treatment. Interestingly, gene delivery was cardiac-selective and beneficial effects on function persisted for 2 weeks. Moreover, beta2AR gene transfer ameliorated LV dysfunction following surgery such that there were no significant differences between non-operated controls and animals treated with Adeno-beta2AR during CPB and cardioplegic arrest. CONCLUSIONS: Reduced betaAR density and impaired LV function were present following CPB and cardioplegic arrest. Cardiac-selective beta2AR gene transfer during CPB resulted in amelioration of LV dysfunction after cardiac surgery. Such a technique may offer a new approach to post-operative ventricular support.

Animals↗
PubMed2004

Dose dependent effects of cardiac beta2 adrenoceptor gene therapy.

BACKGROUND: Adenoviral-mediated gene transfer during cardiopulmonary bypass (CPB) achieves efficient myocardial transgene expression. The optimal vector dose required to produce not only increased beta adrenoceptor (betaAR) density but, more importantly, enhanced left ventricular (LV) function is unknown. In addition, it is unclear if absent extracardiac expression in preliminary studies represented cardiac specific, as opposed to selective gene delivery, as a consequence of low vector doses. MATERIALS AND METHODS: Adenoviral vector encoding the human beta(2) adrenoceptor (Adeno-beta(2)AR) was delivered to cardioplegic arrested hearts of neonatal piglets during CPB in three doses ranging from 5 x 10(11) total viral particles (tvp) to 2 x 10(12) tvp. Control animals received adenoviral vector encoding beta galactosidase (Adeno-betagal) or PBS (PBS). LV and liver betaAR density and in vivo LV function were assessed 5 days later. RESULTS: Elevated LV betaAR density was present after delivery of Adeno-beta(2)AR at all doses. Piglets which received 5 x 10(11) tvp and 1 x 10(12) tvp Adeno-beta(2)AR demonstrated enhanced LV dP/dt(max) but in those receiving 2 x 10(12) tvp LV dP/dt(max) was unchanged. Moreover, at this higher dose of adenoviral vector the detrimental effects of cardiac inflammation and extracardiac gene overexpression became apparent. CONCLUSIONS: Although the highest increase in cardiac betaAR density occurred after high-dose Adeno-beta(2)AR, LV dP/dt(max) was not enhanced. Moreover, significant extracardiac gene expression was present at this dose, emphasizing the need for careful dose response studies in gene therapy. However, cardiac selective beta(2)AR overexpression does occur following adenoviral vector delivery during CPB and cardioplegic arrest resulting in enhanced LV dP/dt(max).

Adenoviridae↗
PubMed2004

Gene delivery to aortocoronary saphenous vein grafts in a large animal model of intimal hyperplasia.

OBJECTIVE: More than 50% of aortocoronary saphenous vein grafts are occluded 10 years after surgery. Intimal hyperplasia is an initial, critical step in the progression toward occlusion. To date, no clinically relevant large animal models of aortocoronary saphenous vein graft intimal hyperplasia have been fully characterized. Gene therapy holds promise as a novel treatment for aortocoronary saphenous vein graft intimal hyperplasia. The 2 objectives of this study are to characterize a canine model of aortocoronary saphenous vein graft intimal hyperplasia and to demonstrate that ex vivo gene delivery is possible in these grafts using adenoviral vectors. METHODS: Ten dogs underwent aortocoronary bypass grafting using saphenous veins. Six dogs underwent serial arteriograms to monitor graft patency. On postoperative day 90, the dogs were killed and their grafted and nongrafted saphenous veins were studied histologically. Four dogs underwent the same procedure, but their saphenous veins were treated with 1 x 10(12) total viral particles of a replication-deficient, recombinant adenovirus containing beta-galactosidase (n = 2) or the beta-adrenergic receptor kinase carboxyl terminus (n = 2). These animals were killed on postoperative day 7 for determination of transgene expression. RESULTS: All grafts were demonstrated patent by arteriogram before the animals were killed. The mean intimal area of the saphenous vein grafts was increased when compared with that of the nongrafted saphenous veins (2.83 mm(2) vs 0.09 mm(2), P <.0008). Adenoviral-treated saphenous vein grafts demonstrated positive transgene expression either by X-gal staining (beta-galactosidase) or Northern analysis (beta-adrenergic receptor kinase carboxyl terminus). CONCLUSION: This study characterizes a clinically relevant canine model of aortocoronary saphenous vein graft intimal hyperplasia. In addition, it demonstrates that adenoviral vectors can be delivered ex vivo to the saphenous vein graft vessel wall at subphysiologic distension pressures. This model may be used in future studies to manipulate molecular targets critical in aortocoronary saphenous vein graft intimal hyperplasia.

Animals↗