Abstract: Objective To determine the effects of oxidative stress reaction on intima hyperplasia after autologous vein grafting. Methods Seventy female SpragueDawley(SD) rats were randomly divided into a control group(n=10) and an experimental group (n=60). The experimental group was then divided into six time points of one day; one, two, four, and six weeks; and two months after surgery; with 10 rats for each time point. Autologous vein grafting models were established. At each time point the designated rats were anaesthetized, and the grafts were isolated and stained with HE. The same length of external jugular vein was cut from each rat in the control group. The neointima to tunica media area ratios (I/M) were measured with acomputerized digital image analysis system. Nuclear factorkappa B (NF-κB) and copper zinc superoxide dismutase (CuZnSOD) were detected byimmunohistochemistry. The concentration of malondialdehyde (MDA) in serum was analyzed by colorimetry. Results In the control group, expression levels of NF-κB and CuZnSOD were low. In the experimental group, expression of NF-κB increased after the operation and peaked two weeks later. The plateau was sustained for about one month, and then the level of expression declined gradually, reaching the baseline at the twomonth time point. The expression of CuZnSOD increased gradually after the operation and peaked one week later, then declined to the normal level after 2-3 weeks at the plateau. In the control group, the concentration of serum MDA was 4.966±1.346 nmol/ml. In the experimental -group, the-MDA concentration increased dramatically after the operation, then-declined from its highest level at the oneday time point (21.161±2.174 nmol/ml) to the normal level at two months (6.208±2.908 nmol/ml) after the operation (P＜0.05). In the control group, I/M was 0.2096±0.0253, while in the experimental group, it was higher one week after the operation (0.6806±0.0737) and peaked at four weeks (1.4527±0.0824), falling to 1.0353±00656 at six weeks and 0.9583±0.0516 attwo months (P＜0.05) for the experimental and control groups). Conclusion Endothelial cell injury initiates an oxidative stress reaction after autologous vein grafting and augments inflammation by activating NF-κB, thus playing an important role in inducing restenosis of the grafted vein.
To evaluate the implantation effect of artificial vascular grafts with recombinant fibrinolytic enzyme factor II (rF II)-immobil ized lumina in animal test. Methods Four mm internal diameter (ID) polyurethane (PU) artificial vascular grafts were prepared by di pping and leaching method. The micro-pore size and morphology of the graft walls were observed by SEM. The graft lumina were immobil ized with rF II. Twenty hybrid male dogs [weighing (20 ± 1) kg] were used for animal model of carotid artery defect and were randomly divided into 3 groups: rF II -immobil ized PU group, no rF II -immobil ized PU group and expanded polytetrafluoroethylene (ePTFE) group. The vascular grafts were implanted for repairing injured segments of carotid artery in dogs. The general health state of animals was recorded. At 30 days and 60 days,the patency rate of every group was calculated. At 60 days IDs were measured, cell prol iferation in neointima was inspected by l ight microscope, morphology on neointima was observed by SEM. Results The ID of the PU vascular grafts was (3.74 ± 0.06) mm, wall thickness was 0.4-0.6 mm, the wall density was 0.25 g/cm3, the porosity was 79.8%, racical compl iance was 8.57%/100 mmHg. In the wall, micropores were well distributed and opened-pores structure was observed. Pore size was (140 ± 41) μm in the outside layer, pore size was (100 ± 3) μm in the inside layer, thickness ratio of outside / inside layers was 2 ∶ 1, the pore size was (40 ± 16) μm on the lumina surface. After operation the wounds on neck healed, all the animals survived and had no compl ication. At 30 days and 60 days after implantation, the patency rate for rF II -immobil ized PU group were 100% and 66.7%, for no rF II -immobil ized PU group were 66.7% and 33.3%, and for ePTFE group were 67.7% and 0 respectively, but at 60 days there were thrombosis at anastamotic sites of some grafts occluded. Before operation the IDs for rF II-immobil ized PU group, no rF II -immobil ized PU group and ePTFE group were (3.74 ± 0.06), (3.74 ± 0.06) and (4.00 ± 0.03) mm, at 60 days after operation the IDs were (4.51 ± 0.05), (4.31 ± 0.24) and (4.43 ± 0.12) mm respectively, showing no statistically significant differences between 3 groups (P gt; 0.05). Histological inspection indicated that at 15 days a layer of plasma protein deposited on the lumina, at 30 days some cells adhered to the lumina, at 60 days neointima could be observed on the lumina. Thickness of the neointima became larger with implantation time. At 60 days neointima thickness at proximal end, middle site and distal end ofgraft were (560 ± 22), (78 ± 5) and (323 ± 31) μm respectively for rF II -immobil ized PU group. The results of SEM showed that neointima surface consisted of flat and long cells which long axes ranged with blood flow direction and was similar to lumina morphology of carotid artery of dog. Conclusion Immobil ization of rF II to lumina of grafts could enhance fibrinolytic activity and inhibited formation of thrombo-embol ia which led to an increase in patency rate after implantation.
Objective To investigate an inhibitive effect of the chitosan nanoparticles with the proliferation cell nuclear antigen （PCNA）-antisense oligo deoxy nucleotides (ASODN) on the intimal cell proliferation after the vein grafting.Methods Fiftyfour male SD rats, weighing 450-600g, were randomly divided in the experimental group and the control group of 27 rats each. In the experimental group, the chitosan nanoparticles with PCNAASODN were infused into the anastomosis segment of the right jugular artery and vein; then, the anastomosis segment was transplanted to the jugular artery on the same side. The rats in the control group were infused with normal saline by the same procedures. There were 24 rats in each group which used to experiment. The hemodynamic data were obtained from the Doppler ultrasound examinations at 1, 2, 3 and 4 weeks. The specimens were taken. Immunohistochemistry, Westernblot, and bloodvesselwall histopathology were performed at the different week points. Results There was no significant difference in the thrombogenesis rate between the experimental group and the control group (3/27 vs. 3/27,P＞0.05). During the 4 week observation, PCNA Westernblot showed that the PCNA level was lower in the grafted vein and the anastomosis segment in the experimental group than in the control group. The indexes of the PCNA postive proliferating cells in the intimal area (0.13%±0.11%，0.79%±0.28%，0.45%±0.29%, 0.43%±0.25%) and the medial area (1.90%± 0.84%，2.11%±0.98%，2.48%±0.77%，2.17%±0.36%) were significantlydecreased at 1,2,3 and 4 weeks in the experimental group when compared with those in the control group（P＜0.05）. The lumen areas in the grafted vein (88.71±16.96，95.98±21.44，88.48±32.81，97.86±34.11 μm 2) and the anastomosis segment (41.49±3.34，45.15±11.65，46.27±8.90，51.62±8.85 μm 2) were significantly greater in the experimental group than in the control group (P＜0.05). The ratios of the initmal area to the medial area in the grafted vein (22.73%±3.11%，32.40%±4.55%，45.14%±3.19%，45.70%±5.01%) and the anastomsis segment (41.49%±3.34%，45.15%±11.65%，46.27%±890%，51.62%±8.85%) were significantly smaller in the experimental group than in the control group（P＜0.05）. The maximum velocities (Vmax) of the blood flow inthe grafted vein and the anastomsis segment were almost the same in the two groups at 1 week, but had different changes at the next 3 weekpoints. In the control group, the Vmax of the blood flow gradually increased and at 3 weeks it reached the peak point; however, at 4 weeks it decreased. In the experimental group,the Vmax of the blood flow gradually decreased, and at 3 weeks it decreased to the lowest point; however, at 4 weeks it increased. So, at 4 weeks the Vmax of the blood flow in the grafted vein and the anastomsis segment was almost the samein the two groups. There was no significant difference in the Vmax of the bloodflow between the two groups (P＞0.05), but in the same group there wasa significant difference at the different time points. Conclusion The chitosan nanoparticles with PCNAASODN can effectively inhibit the intimal cell proliferation after the grafting of the blood vessel, so that the neointimal thickening can be prevented.