Vincent J. Pompili

Expression and Function of Recombinant Endothelial Nitric Oxide Synthase Gene in Canine Basilar Artery

Endothelial NO synthase (eNOS) is an enzyme responsible for the production of a potent vasodilator and a key regulator of vascular tone, NO. In peripheral arteries, expression of a recombinant eNOS gene increases production of NO in the blood vessel wall. This approach appears to be a promising strategy for gene therapy of cerebrovascular disease. The major objective of the present study was to determine whether a recombinant eNOS gene (AdCMVNOS) can be functionally expressed in cerebral arteries. Replication-defective recombinant adenovirus vectors encoding bovine eNOS and Escherichia coli beta-galactosidase (AdCMVLacZ) genes, driven by the cytomegalovirus promoter, were used for ex vivo gene transfer. Rings of canine basilar artery were incubated with increasing titers of the vectors in MEM. Twenty-four or forty-eight hours after gene transfer, expression and function of AdCMVNOS were evaluated by (1) immunohistochemical staining, (2) isometric tension recording, and (3) cGMP radioimmunoassay. Transfection with AdCMVNOS resulted in the expression of recombinant eNOS protein in the vascular adventitia and endothelium, associated with significantly reduced contractile responses to UTP and enhanced endothelium-dependent relaxation to calcium ionophore A23187. Basal production of cGMP was significantly increased in the transfected vessels. The reduced contractions to UTP with increased cGMP production were reversed by a NOS inhibitor, N(G)-monomethyl-L-arginine. Contractions to UTP or production of cGMP were not affected in arteries transfected with AdCMVLacZ reporter gene. The results of the present study represent the first successful transfer and functional expression of recombinant eNOS gene in cerebral arteries. Our findings suggest that cerebral arterial tone can be modulated by recombinant eNOS expression in the vessel wall.

Expression and function of a recombinant endothelial nitric oxide synthase gene in porcine coronary arteries

OBJECTIVES Direct gene transfer of exogenous nitric oxide synthase, with the subsequent increase in nitric oxide production, could represent a potential therapeutic strategy in the treatment of vascular proliferative disorders. The goal of the present study was to determine if porcine coronary arteries could be transduced with an adenoviral vector encoding endothelial nitric oxide synthase (Ad.CMVeNOS) resulting in functional expression. METHODS AND RESULTS Segments of porcine right coronary artery were exposed for 1 h at 37 degrees C to either replication-deficient adenovirus encoding bovine endothelial nitric oxide synthase (Ad.CMVeNOS, 5 x 10(9) pfu/ml) or control adenovirus encoding Escherichia coli beta-galactosidase (Ad.CMVLacZ, 5 x 10(9) pfu/ml). Immunohistochemistry with a monoclonal antibody specific for nitric oxide synthase (NOS) demonstrated recombinant gene expression in both the endothelial and adventitial layers of Ad.CMVeNOS transduced coronaries with only endogenous NOS confirmed in the endothelium of Ad.CMVLacZ arteries. Coronary arteries transduced with Ad.CMVeNOS yielded 517 +/- 110 (mean +/- S.E.M.) nM/ng nitrite while vessels transduced with Ad.CMVLacZ yielded 126 +/- 84 nM/ng (P < 0.05, n = 6). Isometric tension recording, following prostaglandin F2 alpha constriction, documented a reduced tension in Ad.CMVeNOS transduced coronaries, compared to matched Ad.CMVLacZ coronaries (6.10 +/- 1.08 g vs. 8.45 +/- 1.19 g, respectively, P = 0.05, n = 8). This tension differential was eliminated with prior incubation in NG-monomethyl-L-arginine (L-NMMA, 10(-4) M). The EC50 for calcium ionophore relaxation of Ad.CMVeNOS coronary arteries was reduced compared to Ad.CMVLacZ (-7.90 +/- 0.03 logM vs. -7.26 +/- 0.11 logM, respectively, P < 0.05, n = 8). CONCLUSIONS These studies demonstrate successful transfer of endothelial nitric oxide synthase into porcine coronary arteries as verified by histochemical localization of recombinant protein with an increase of nitric oxide release as demonstrated by enhanced nitrite production and an alteration in vasomotor function.

Left internal mammary artery graft perforation due to high-pressure stent deployment

Perforation of newly placed left internal mammary artery (LIMA) grafts due to stent deployment is an infrequent but potentially dangerous complication of coronary interventions. It may lead to brisk hemorrhage and massive cardiac tamponade requiring emergent pericardiocentesis and surgery. We report a case of a LIMA graft perforation following stent deployment with a high‐pressure balloon 12 days after surgery. The patient was treated with emergent pericardiocentesis, rapid autotransfusion of the pericardial aspirate into the systemic circulation, and surgical repair of the ruptured vessel. Cathet. Cardiovasc Intervent. 47:199–202, 1999.

Enhanced angiogenesis and unfavorable remodeling in injured porcine coronary artery lesions: Effects of local basic fibroblast growth factor delivery

There is interest in the role of growth factors in the genesis of arterial remodeling. We studied local administration of basic fibroblast growth factor (bFGF) to coronary lesions to determine whether there is a difference in remodeling and whether neovascularization could be induced in such stenoses and distal myocardium. Pigs were randomized to balloon infusion of either saline or bFGF at each thermally injured arterial site. After the animals were killed, their internal elastic lamina, neointima, and lumen areas were measured. Capillaries were counted in the arteries and myocardium. There was a greater loss of lumen and internal elastic lamina in the bFGF group. The neointima, media, and myocardium in the bFGF treated arteries had statistically more capillaries. This study showed that local intracoronary bFGF, at a dose that results in arterial luminal revascu larization in injured segments, adversely affects arterial remodeling. Thus, the angio genic response to exogenous bFGF may be offset by concomitant shrinkage of injured arterial segments.

Saphenous Vein Graft Ectasia: An Unusual Late Complication of Coronary Artery Bypass Surgery A Case Report

Aneurysms and ectasias of saphenous vein grafts are infrequent complications of coronary artery bypass surgery. They usually present as an expanding asymptomatic mediastinal mass on chest x-ray film or computed tomography scan. Though rare, they must be excluded from the differential diagnosis of mediastinal masses to avoid potentially dangerous needle biopsy. The authors describe ectasia of a saphenous vein graft in a 62- year-old man 14 years after coronary artery bypass surgery. The relevant literature is also discussed.

Vascular Cell Proliferation Dynamics: Implications for Gene Transfer and Restenosis

Pharmacologic treatment of restenosis following coronary angioplasty has completely failed. The most widely accepted cause is formation of neointimal hyperplasia, considered a result of uncontrolled medial smooth muscle cell proliferation [1–5]. Studies in the rat carotid artery injury model has been the basis of this paradigm, having been documented in many studies [6, 7]. Therapies aimed at inhibiting proliferation have been quite successful in rat arterial injury [8, 9]. Yet when applied to large scale patient trials, these therapies have failed to exhibit any effect whatsoever on the loss of minimal lumen diameter (MLD) [10]. Reasons for these failures are unclear, but may relate in part to an incomplete understanding of cell kinetics in the growth of human neointimal hyperplasia. The literature is conflicting regarding the role of proliferation in human restenosis. Two studies of human restenotic lesions obtained using directional atherectomy demonstrated opposite conclusions. Pickering and colleagues [11] found peak cellular proliferation rates of about 20%, while in a similar study, O’Brien [12] reported a proliferation rate of less than 1%. Much debate has surfaced about the reasons for these divergent results, but centers on questions of technical factors such as tissue fixation methods and visual interpretation of positive cells by proliferating cell nuclear antigen (PCNA) staining.