Gang Zhao

Formulation of nanoparticle-eluting stents by a cationic electrodeposition coating technology: efficient nano-drug delivery via bioabsorbable polymeric nanoparticle-eluting stents in porcine coronary arteries.

OBJECTIVESnThe objective of this study was to formulate a nanoparticle (NP)-eluting drug delivery stent system by a cationic electrodeposition coating technology.nnnBACKGROUNDnNanoparticle-mediated drug delivery systems (DDS) are poised to transform the development of innovative therapeutic devices. Therefore, we hypothesized that a bioabsorbable polymeric NP-eluting stent provides an efficient DDS that shows better and more prolonged delivery compared with dip-coating stent.nnnMETHODSnWe prepared cationic NP encapsulated with a fluorescence marker (FITC) by emulsion solvent diffusion method, succeeded to formulate an NP-eluting stent with a novel cation electrodeposition coating technology, and compared the in vitro and in vivo characteristics of the FITC-loaded NP-eluting stent with dip-coated FITC-eluting stent and bare metal stent.nnnRESULTSnThe NP was taken up stably and efficiently by cultured vascular smooth muscle cells in vitro. In a porcine coronary artery model in vivo, substantial FITC fluorescence was observed in neointimal and medial layers of the stented segments that had received the FITC-NP-eluting stent until 4 weeks. In contrast, no substantial FITC fluorescence was observed in the segments from the polymer-based FITC-eluting stent or from bare metal stent. The magnitudes of stent-induced injury, inflammation, endothelial recovery, and neointima formation were comparable between bare metal stent and NP-eluting stent groups.nnnCONCLUSIONSnTherefore, this NP-eluting stent is an efficient NP-mediated DDS that holds as an innovative platform for the delivery of less invasive nano-devices targeting cardiovascular disease.

Local Delivery of Anti-Monocyte Chemoattractant Protein-1 by Gene-Eluting Stents Attenuates In-Stent Stenosis in Rabbits and Monkeys

Objective—We have previously shown that the intramuscular transfer of the anti–monocyte chemoattractant protein-1 (MCP-1) gene (called 7ND) is able to prevent experimental restenosis. The aim of this study was to determine the in vivo efficacy and safety of local delivery of 7ND gene via the gene-eluting stent in reducing in-stent neointima formation in rabbits and in cynomolgus monkeys. Methods and Results—We here found that in vitro, 7ND effectively inhibited the chemotaxis of mononuclear leukocytes and also inhibited the proliferation/migration of vascular smooth muscle cells. We then coated stents with a biocompatible polymer containing a plasmid bearing the 7ND gene, and deployed these stents in the iliac arteries of rabbits and monkeys. 7ND gene-eluting stents attenuated stent-associated monocyte infiltration and neointima formation after one month in rabbits, and showed long-term inhibitory effects on neointima formation when assessments were carried out at 1, 3, and 6 months in monkeys. Conclusions—Strategy of inhibiting the action of MCP-1 with a 7ND gene-eluting stent reduced in-stent neointima formation with no evidence of adverse effects in rabbits and monkeys. The 7ND gene-eluting stent could be a promising therapy for treatment of restenosis in humans.

Stent-Based Local Delivery of Nuclear Factor-κB Decoy Attenuates In-Stent Restenosis in Hypercholesterolemic Rabbits

Background— Nuclear factor-&kgr;B (NF-&kgr;B) plays a critical role in the vascular response to injury. However, the role of NF-&kgr;B in the mechanism of in-stent restenosis remains unclear. We therefore tested the hypothesis that blockade of NF-&kgr;B by stent-based delivery of a cis-element “decoy” of NF-&kgr;B reduces in-stent neointimal formation. Methods and Results— Stents were coated with a polymer containing or not containing NF-&kgr;B decoy, which represented a fast-release formulation (<7 days). Bare, polymer-coated, and NF-&kgr;B decoy–eluting stents were implanted in iliac arteries of hypercholesterolemic rabbits. Increased NF-&kgr;B activity was noted at early stages after stenting, which was suppressed by stent-based delivery of NF-&kgr;B decoy. NF-&kgr;B decoy–eluting stents also reduced monocyte infiltration and monocyte chemoattractant protein-1 expression and suppressed CD14 activation on circulating leukocytes. Importantly, NF-&kgr;B decoy–eluting stents attenuated neointimal formation on day 28. There was no evidence of an incomplete healing process (persistent inflammation, hemorrhage, fibrin deposition, impaired endothelial regeneration) at the site of NF-&kgr;B decoy–eluting stents. Transfection of NF-&kgr;B decoy suppressed proliferation of human coronary artery smooth muscle cells in vitro. No systemic adverse effects of NF-&kgr;B decoy were detected. Conclusions— Stent-based local delivery of NF-&kgr;B decoy reduced in-stent neointimal formation with no evidence of incomplete healing. These data suggest that this strategy may be a practical and promising means for prevention of in-stent restenosis in humans.

Angiotensin II Type 1 Receptor Blockade Attenuates In-Stent Restenosis by Inhibiting Inflammation and Progenitor Cells

The precise mechanism by which angiotensin II type 1 receptor blocker reduces in-stent restenosis in clinical trials is unclear. We, therefore, investigated the mechanism of in-stent neointima formation. Male cynomolgus monkeys and rabbits were fed a high-cholesterol diet and were allocated to untreated control and type 1 receptor blocker groups. Five days after grouping, multilink stents were implanted in the iliac artery. The type 1 receptor blocker reduced the development of in-stent neointima formation by ≈30% in rabbits and monkeys. To investigate potential mechanisms, we examined the expression of renin-angiotensin system markers, all of which increased in monocytes and smooth muscle-like cells in the neointima and media within 7 days. The type 1 receptor blocker attenuated increased oxidative stress, the enhanced expression of markers of the rennin-angiotensin system and monocyte chemoattractant protein-1, and macrophage infiltration. The effects of type 1 receptor blocker on the differentiation of peripheral blood mononuclear cells into vascular progenitor cells were also examined. Treatment with type 1 receptor blocker suppressed the enhanced differentiation to smooth muscle progenitor cells induced by stenting. The type 1 receptor blocker attenuated in-stent neointima formation by inhibiting redox-sensitive inflammatory changes and by reducing recruitment of the progenitor cells. These potential actions of type 1 receptor blocker on inflammation and progenitor cells constitute a novel mechanism of suppression of in-stent restenosis by type 1 receptor blocker.