L-arginine improves endothelium-dependent vasorelaxation and reduces intimal hyperplasia after balloon angioplasty.

Introduction: Balloon angioplasty is a commonly applied procedure for treating atherosclerotic vascular diseases. However, the maintenance of long-term lumen patency is relatively difficult due to the occurrence of restenosis. Previous research has shown that the occurrence of vascular wall inflammation is associated with higher rates of restenosis. Sophocarpine (SPC) can exert various therapeutic effects such as anti-oxidation, anti-inflammation, anti-tumor, antivirus and immune regulation. This study aimed to investigate whether SPC can alleviate intimal hyperplasia following balloon injury in a rat carotid artery model. Methods: Twenty Sprague–Dawley rats were randomly assigned to four groups: (i) control, (ii) balloon injury, (iii) balloon injury followed by saline injection, and (iv) balloon injury followed by SPC administration. Each group contained five rats. A high-pressure balloon of 3 mm × 20 mm was placed in the carotid artery. The balloon was inflated to a pressure of 8 atmospheres to carry out rat carotid artery balloon injury model. The areas of neointimal and media were determined by Verhoeff_Van Gieson staining, and the intima-to-media (I:M) ratios were subsequently evaluated. After that, the protein levels of IL-6, IL-1β, MCP-1, NF-κB, TNF-α, VCAM-1, ICAM-1 and eNOS were measured. Results: The ratio of I:M was remarkably higher in the balloon injury group than in the control group (p < 0.01). SPC could significantly decrease the ratio of I:M compared with the balloon injury group (p < 0.01). Besides, the protein levels of IL-6, IL-1β, MCP-1, NF-κB, TNF-α, ICAM-1 and VCAM-1 were increased in rat carotid arteries exposed to balloon injury (p < 0.01), and treatment with SPC could attenuate these effects (p < 0.05). Furthermore, balloon injury inhibited the protein expression of eNOS (p < 0.01), and SPC could elevate its level (p < 0.05). Conclusions: SPC could alleviate an intimal hyperplasia in balloon-injured carotid artery, and the mechanisms underlying this protective effect might be due to its inhibitory potency against inflammation signals. Our study also implies the potential applicability of SPC in treating restenosis after balloon angioplasty.

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Abstract 311: TGFb/Smad3 Stimulation Drives Smooth Muscle Cell De-differentiation

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.33.suppl_1.a311 ◽

2013 ◽

Vol 33 (suppl_1) ◽

Author(s):

Daniel M DiRenzo ◽

Xudong Shi ◽

Stephen Seedial ◽

Lian-wang Guo ◽

Bo Liu ◽

...

Keyword(s):

Gene Expression ◽

Smooth Muscle ◽

Balloon Angioplasty ◽

Intimal Hyperplasia ◽

Cellular Proliferation ◽

Smooth Muscle Actin ◽

Tgfβ Signaling ◽

And Migration ◽

Proliferation And Migration

Restenosis, or vessel re-narrowing, occurs in approximately 25-50% of arterial interventions involving balloon angioplasty due to the formation of a proliferative plaque in the vessel lumen termed neo-intimal hyperplasia. Arterial smooth muscle cells (SMCs) contribute to neo-intimal hyperplasia through a de-differentiation process that includes downregulation of their contractile gene expression and conversion to a phenotype that includes proliferation, migration, and matrix synthesis. Expression of TGFβ and its downstream signaling protein, Smad3, are greatly upregulated following vascular injury, including balloon angioplasty. Classically, TGFβ signaling has been shown to suppress SMC proliferation and migration in vitro, however, Smad3 overexpressing SMCs demonstrate enhanced proliferation and migration. Furthermore, overexpression of Smad3 in rat carotid arteries enhances neo-intimal hyperplasia following balloon angioplasty. These results lead us to hypothesize that TGFβ signaling, in the context of upregulated Smad3, drives SMC de-differentiation leading to enhanced cellular proliferation and migration. We utilized primary rat SMCs infected with adenovirus constructs overexpressing Smad3 or GFP control and performed gene expression microarrays 24 hours following TGFβ administration. We observed statistically significant (p<0.05) upregulation of 145 genes and downregulation of 76 genes by more than 3-fold. GO term analysis revealed that genes involved in embryonic tissue development (41 genes) and stem/progenitor cell differentiation (27 genes) were significantly enriched in TGFβ/Smad3 stimulated cells. Confirmatory qRT-PCR demonstrated that the contractile genes SM-MHC, smooth muscle actin, and calponin were significantly downregulated -6.3, -2.7 and -2.1 fold, respectively. In contrast, stem/developmental related genes Cxcr4, Cd34, Wnt11, Wnt2b and IL11 were significantly upregulated by 105.2, 22.3, 11.5, 14.0, and 12.5 fold, respectively. These results strongly suggest that TGFβ/Smad3 stimulation is a powerful de-differentiation signal in SMCs and plays an important role in the development of neo-intimal hyperplasia.

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