Role of Girdin in intimal hyperplasia in vein grafts and efficacy of atelocollagen-mediated application of small interfering RNA for vein graft failure.

Intimal hyperplasia is a major obstacle to patency in grafted veins. Although migration and proliferation of vascular smooth muscle cells (SMCs) pivotally affect the vascular remodeling process, no therapy has been established to prevent intimal hyperplasia of vein grafts. We previously reported that the actin-binding protein Girdin crucially affects arterial remodeling. In this study, we investigated the role of Girdin in venous SMCs and evaluated a therapeutic strategy for vein graft failure in vivo using small interfering RNA (siRNA) that targets Girdin. We investigated the relationship between Girdin expression and intimal hyperplasia using a rabbit vein graft model. Vein grafts under low-flow conditions were performed in Japanese White rabbits. For in vitro analyses, we isolated primary venous SMCs from vein graft neointima. siRNA that targets Girdin was mixed with atelocollagen, which stabilizes and releases nucleic acid reagents slowly and is applied perivascularly to the vein grafts at operation. Intimal hyperplasia was evaluated 4 weeks later. In the rabbit model, increased Girdin expression was seen in the neointima after the grafting operation. Using primary venous SMCs, we showed that Girdin is required for rearrangement of the actin cytoskeleton in venous SMCs and that siRNA-mediated Girdin knockdown significantly reduced venous SMC migration and proliferation. Girdin knockdown via perivascular application of siRNA using atelocollagen markedly reduced intimal thickening after the grafting operation. Depletion of Girdin attenuated venous SMCs migration and proliferation in vitro and intimal hyperplasia in vein grafts in vivo. Our findings suggest that Girdin affects migration and proliferation of vascular SMCs in vein grafts and that controlled release of Girdin siRNA using atelocollagen could be a novel therapeutic strategy for vein graft failure.

Miyachi H ，Mii S ，Enomoto A ，Murakumo Y ，Kato T ，Asai N ，Komori K ，Takahashi M ... -  《-》

Controlled release of small interfering RNA targeting midkine attenuates intimal hyperplasia in vein grafts.

Banno H ，Takei Y ，Muramatsu T ，Komori K ，Kadomatsu K ... -  《JOURNAL OF VASCULAR SURGERY》

Effect of microRNA-145 to prevent vein graft disease in rabbits by regulation of smooth muscle cell phenotype.

Because microRNA-145 (miR-145) is a specific mediator in the regulation of the proliferation and differentiation of smooth muscle cells, we investigated the effect of miR-145 on the intimal hyperplasia in the rabbit model of vein graft disease using electroporation-mediated gene transfer. The right jugular vein of male Japanese white rabbits was harvested and transduced with miR-145-encoding plasmids using an electroporator and then interposed in the carotid artery. At 2 or 4 weeks postoperatively, the venous graft was explanted, and the intimal thickness and intima/media area ratio were evaluated. Furthermore, 3 days after implantation, the myocardin and serum response factors were measured using real-time polymerase chain reaction. At 2 weeks after implantation, immunohistochemical investigations using mature smooth muscle markers, myosin heavy chain smooth muscle-1 and -2, and proliferation marker Ki-67 were performed. MiR-145 transduction significantly reduced the neointimal thickness at both 2 and 4 weeks (2 weeks, 52.1 ± 15.7 vs 113.2 ± 26.9 μm, P < .05, n = 6; 4 weeks, 42.4 ± 4.8 vs 136.5 ± 38.3 μm, P < .05, n = 8), and it also significantly reduced the intima/media area ratio at 4 weeks (0.22 ± 0.04 vs 1.13 ± 0.23, P < .01, n = 8). Additionally, it upregulated the mRNA expression level of myocardin compared with that in the grafts that did not receive gene transfer. Smooth muscle-2 and Ki-67 expression revealed that miR-145 transduced grafts contained more smooth muscle-2-positive mature smooth muscle cells and fewer Ki-67-positive proliferating cells. Nonviral transduction of miR-145 into the bypass graft could be a novel option for preventing intimal hyperplasia in vein graft disease.

Ohnaka M ，Marui A ，Yamahara K ，Minakata K ，Yamazaki K ，Kumagai M ，Masumoto H ，Tanaka S ，Ikeda T ，Sakata R ... -  《-》

Inhibitory Effect of TLR4 Gene Silencing on Intimal Hyperplasia of Vein Grafting.

The present study aimed to explore the regulating effect of Toll-like receptor 4 (TLR4) on intimal hyperplasia in rat vein grafts. Rat models of external jugular vein carotid artery bypass grafting were established. Afterward, TLR4 small interfering RNA (siRNA) recombinant plasmids were constructed, which were transfected into rat vein graft bypass to study the effect of TLR4 silencing on intimal hyperplasia and to explore the underlying mechanisms. Real-time polymerase chain reaction and Western blot were used to detect the expression levels of TLR4 and inflammatory factors in TLR4 siRNA-transfected vein graft bypass. The intimal thickness was evaluated using hematoxylin-eosin staining. Compared with the scramble siRNA group, the intimal thickness of vein grafting was decreased significantly, while the inflammatory factors including interleukin (IL) 1β, IL-6, and tumor necrosis factor α in grafted vein were dramatically downregulated in the TLR4 siRNA group. These results showed that local silencing of TLR4 in the vein grafts could inhibit intimal hyperplasia by downregulating the expression of inflammatory factors in the vein grafts, suggesting that TLR4 can be used as a new target for therapy of vascular intimal hyperplasia.

Zhu Z ，Xu R ，Zheng X ，Wang T ，Li D ，Wang Y ，Liu K ... -  《-》

Small interfering RNA targeting nuclear factor kappa B to prevent vein graft stenosis in rat models.

Intimal hyperplasia plays an important role in vein graft stenosis. Inflammatory injury, especially nuclear factor kappaB (NF-κB) gene activation, is highly involved in stenosis progression. We examined whether neointimal hyperplasia and vein graft stenosis could be inhibited by silencing the NF-κB gene with small interference RNA (siRNA). Sixty adult male Sprague-Dawley rats were randomly divided into a normal vein group, a vein graft group, a scrambled siRNA group, and an NF-κB siRNA group. We performed reverse interpositional grafting of the autologous external jugular vein to the abdominal aorta. Vein grafts were treated with liposome and gel complexes containing NF-κB siRNA or scrambled siRNA. The levels of monocyte chemoattractant protein -1, tumor necrosis factor-α, and NF-κB p65 in vessel tissues were evaluated after surgery for content of proliferating cell nuclear antigen (PCNA) and vascular wall thickness. NF-κB siRNA treated vein graft showed less neointimal formation and fewer positive PCNA cells (P < .05). In addition there were lower levels of, NF-κB p65 protein and of inflammatory mediators (P < .05) compared with the vein graft group. Our study suggested that siRNA transfection suppressed NF-κB expression, reduced inflammatory factors, lessened neointimal proliferation, and suppressed PCNA.

Meng XB ，Bi XL ，Zhao HL ，Feng JB ，Zhang JP ，Song GM ，Sun WY ，Bi YW ... -  《-》