Local Delivery of an Ultra-short-acting Nitric Oxide-releasing Compound, DMHD/NO, Is Highly Effective in Inhibiting Acute Platelet-Thrombus Formation on Injured Arterial Strips

In-stent restenosis limitation with stent-based controlled-release nitric oxide: initial results in rabbits

PURPOSE

To evaluate effect of controlled stent-based release of an NO donor to limit in-stent restenosis in rabbits.

MATERIALS AND METHODS

Bioerodable microspheres containing NO donor or biodegradable polymer (polylactide-co-glycolide-polyethylene glycol) were prepared and loaded in channeled stents. Daily concentrations of NO release from NO-containing microspheres were assayed in vitro. NO- and polymer-containing (control) microsphere-loaded stents were deployed in aortas of New Zealand white rabbits (n = 8). Aortas with stents were harvested at 7 (n = 5) and 28 days (n = 3) and evaluated for cyclic guanosine monophosphate (cGMP) levels (7 days), number of proliferating cell nuclear antigen-positive cells (7 days), and intima-to-media ratio (7 and 28 days), with statistical significance evaluated by using one-way analysis of variance.

RESULTS

NO-containing microspheres released NO with an initial bolus in the 1st week, followed by sustained release for the remaining 3 weeks. Significant increase in cGMP levels and decrease in proliferating cell nuclear antigen-positive cells were found at 7 days for the NO-treated group relative to controls (P <.05). Intima-to-media ratio in the NO-treated group was reduced by 46% and 32% relative to controls at 7 and 28 days, respectively (mean, 0.14 +/- 0.01 [standard error] vs 0.26 +/- 0.02 at 7 days, P <.01; 1.34 +/- 0.05 vs 1.98 +/- 0.08 at 28 days, P <.01).

CONCLUSION

Stent-based controlled release of NO donor significantly reduces in-stent restenosis and is associated with increase in vascular cGMP and suppression of proliferation.

Polymeric-based perivascular delivery of a nitric oxide donor inhibits intimal thickening after balloon denudation arterial injury: role of nuclear factor-kappaB

OBJECTIVES

To examine the effect of a polymeric-based periadventitial delivery of a nitric oxide (NO)-releasing diazeniumdiolate, spermine/NO (SPER/NO), on balloon injury-induced neointimal hyperplasia in rat ileofemoral arteries.

BACKGROUND

Reduced local bioavailability and adverse side effects limit systemic administration of NO to modulate vascular response to injury.

METHODS

A polylactic-polyglycolic acid polymeric matrix containing 2.5% SPER/NO (w/w) was applied around the injured arteries. Quantitative histomorphometry was performed at day 14, proliferating cell nuclear antigen (PCNA) immunohistochemistry at day 3 to assess effects on smooth muscle proliferation and electrophoretic mobility shift assay to evaluate effects on transcription factor, nuclear factor-kappaB (NF-kappaB).

RESULTS

Treatment with SPER/NO reduced the intimal area (0.011 +/- 0.009 vs. 0.035 +/- 0.006 mm2 control, p < 0.01) and the intima to media ratio (0.089 +/- 0.062 vs. 0.330 +/- 0.057 control, p < 0.005). Spermine/nitric oxide produced a profound inhibition of PCNA-positive cells (>75%, p < 0.005) and significantly suppressed the injury-induced activation of NF-kappaB. Vascular cyclic guanosine monophosphate (cGMP) levels were elevated after treatment with the SPER/NO (0.28 +/- 0.03 vs. 0.17 +/- 0.02 pmol/mg tissue control, p < 0.01). The inhibitory effects on neointimal proliferation were localized to the site of application of SPER/NO and were not associated with any changes in platelet aggregation or bleeding time. Neither SPER nor polymer alone had any significant effects on any of the variables examined.

CONCLUSIONS

Polymeric-based perivascular delivery of a NO donor produces a marked localized inhibition of neointimal proliferation in balloon-injured arteries. This phenomenon is associated with suppression of NF-kappaB activation and elevation of the vascular cGMP at the site of injury.

Evidence that high-density lipoprotein cholesterol is an independent predictor of acute platelet-dependent thrombus formation

Plasma total and low-density lipoprotein (LDL) cholesterol are established risk factors for atherosclerotic vascular disease and may also contribute to a prothrombotic risk via enhanced platelet reactivity. This study examines whether high-density lipoprotein (HDL) cholesterol, which is inversely correlated with coronary artery disease, is associated with a reduced thrombogenic potential. Platelet thrombus formation was evaluated by exposing porcine aortic media placed in Badimon perfusion chambers to flowing nonanticoagulated venous blood for 5 minutes at a shear rate of 1,000 s(-1). Forty-five subjects, 23 normal (LDL 104 +/- 31, HDL 50 +/- 15 mg/dl) and 22 hypercholesterolemic (LDL 181 +/- 45, HDL 41 +/- 10 mg/dl) patients without coronary artery disease were studied. Platelet aggregation and CD62 antigen expression, and assay for circulating prothrombotic factors were also performed. In univariate analysis platelet thrombus formation correlated with weight (r = 0.33, p = 0.03), diastolic blood pressure (r = 0.39, p = 0.01), HDL cholesterol (r = -0.45, p = 0.003), total/HDL cholesterol (r = 0.43, p = 0.004) and LDL/HDL (r = 0.38, p = 0.01) ratios, and platelet CD62 expression (r = 0.41, p = 0.02). In multiple regression analysis only HDL cholesterol showed significant correlation with platelet thrombus formation (p = 0.03). Platelet aggregation and circulating prothrombotic factors did not correlate with platelet thrombus formation. A comparison between normal and hypercholesterolemic subjects revealed enhanced thrombus area (0.026 +/- 0.20 vs 0.045 +/- 0.039 mm2/mm; p = 0.04), resting CD62 expression (6 +/- 7% vs 15 +/- 10% positive platelets, p = 0.02), and platelet aggregation (16.7 +/- 5.2 vs 21.7 +/- 6.7 ohms, p = 0.04) in hypercholesterolemic subjects. Our results demonstrate that HDL cholesterol is a significant independent predictor of ex vivo platelet thrombus formation.