Surgical injury of rat arteries: genetic control of the remodelling process

Gene therapy with antisense oligonucleotides silencing c-myc reduces neointima formation and vessel wall thickness in a mouse model of vein graft disease

Gene therapy for avoiding intimal hyperplasia of vein grafts after coronary artery bypass grafting is still discussed controversially. A promising application of gene therapy in vein grafts is the use of antisense oligonucleotides to block the expression of genes encoding cell cycle regulatory proteins in vascular smooth muscle cells. C-myc, either directly or by regulating the expression of other proteins, controls cell proliferation, apoptosis and cell survival, tissue remodeling, angiogenesis, cell metabolism, production of inflammatory and anti-inflammatory cytokines, and also participates in cell transformation. Forty C57BL/6J mice underwent interposition of the inferior vena cava from isogenic donor mice into the common carotid artery using a previously described cuff technique. Twenty mice received periadventitial administration of antisense oligonucleotides directed against c-myc (treatment group), the other twenty mice received no treatment (control group). All vein grafts were harvested two weeks after surgery, dehydrated, wax embedded, cut into slides of 2 μm thickness, stained and histologically and immunohistochemically examined under light microscope. In our study, we could show the promising effects of antisense oligonucleotide treatment in a mouse model of vein graft disease including the significant reduction of neointimal, media and total vessel wall thickness with a significantly lower percentage of SMA positive cells, elastic fibres and acid mucopolysaccharides in the neointima and media, a decreased vascularization, and a lower expression of PDGFR ß, MMP-9 and VEGF-A positive cells throughout the whole vein graft wall.

The experimental study of hemodynamic changes and pathological morphology after artery anastomosis

The purpose of this article is to dynamically observe hemodynamic and medium-term pathomorphological changes and to investigate the pathophysiological variation at the vascular anastomotic stoma. Eighteen New Zealand white rabbits underwent right common carotid artery in situ anastomosis, and the hemodynamic changes of anastomotic stoma were recorded by color Doppler ultrasonography before surgery and 5 minutes, 1 week, 2 weeks, 3 weeks, 4 weeks, 8 weeks, 12 weeks, and 16 weeks after surgery. Pathological sections of stoma were made and the pathomorphological changes viewed. Artery anastomoses were preformed successfully in 15 rabbits; 4 rabbits suffered postoperative death. It took 1.22 ± 0.77 hours to complete every operation. All the data involved, mean velocity, peak systolic velocity, and resistant index, had no significant differences between preoperative and postoperative follow-up. The obvious differences were found in the diameters of stoma 5 minutes, 1 week, 2 weeks, and 3 weeks after operation (P values were .002, .001, .003, and .008, respectively). The variance of stoma diameters 2 weeks later was also different from those after 1 week, but no other differences were observed during other weeks. The decrease in stoma diameters after anastomosis was clear, with the maximum decrease occurring 2 weeks after the operation, after which the diameters of stoma became stable 16 weeks after the operation. Some collagens around anastomoses could be found by the pathological sections of stoma, which indicated that the deposition of collagen might be related to the decrease in stoma diameter.

Upregulated TRPC1 channel in vascular injury in vivo and its role in human neointimal hyperplasia

Occlusive vascular disease is a widespread abnormality leading to lethal or debilitating outcomes such as myocardial infarction and stroke. It is part of atherosclerosis and is evoked by clinical procedures including angioplasty and grafting of saphenous vein in bypass surgery. A causative factor is the switch in smooth muscle cells to an invasive and proliferative mode, leading to neointimal hyperplasia. Here we reveal the importance to this process of TRPC1, a homolog of Drosophila transient receptor potential. Using 2 different in vivo models of vascular injury in rodents we show hyperplasic smooth muscle cells have upregulated TRPC1 associated with enhanced calcium entry and cell cycle activity. Neointimal smooth muscle cells after balloon angioplasty of pig coronary artery also express TRPC1. Furthermore, human vein samples obtained during coronary artery bypass graft surgery commonly exhibit an intimal structure containing smooth muscle cells that expressed more TRPC1 than the medial layer cells. Veins were organ cultured to allow growth of neointimal smooth muscle cells over a 2-week period. To explore the functional relevance of TRPC1, we used a specific E3-targeted antibody to TRPC1 and chemical blocker 2-aminoethoxydiphenyl borate. Both agents significantly reduced neointimal growth in human vein, as well as calcium entry and proliferation of smooth muscle cells in culture. The data suggest upregulated TRPC1 is a general feature of smooth muscle cells in occlusive vascular disease and that TRPC1 inhibitors have potential as protective agents against human vascular failure.