A Novel Modification of the Murine Elastase Infusion Model of Abdominal Aortic Aneurysm Formation.

To create a novel procedure that will decrease the mortality of experimental animals in the intraarterial infusion of elastase abdominal aortic aneurysm (AAA) model. Novel models were created by means of direct puncture in the infrarenal abdominal aortic aorta, intraluminal elastase in the 1-cm segment of abdominal aorta. Femoral artery cannula approach and infusing with elastase was considered as the traditional group and that infusing with saline solution as the control group. Survival rate, morphology and histology of aneurysms, and inflammation mediators were calculated. Among the 36 rats, the average length from testicular arteries to left iliolumbar artery was 1.18 ± 0.22 cm, and 77.8% of them were longer than 1 cm. Procedure time was significantly shorter in novel group than that in 2 other groups (P = 0.006; P < 0.0001). During 24 hr postoperation, no death was observed in the novel group. Within 4 wk, survival rate in the control group was 60.6% and 80.8% in the novel group whereas 41.0% in the traditional group. Till the second week, all rats in the traditional and novel group had formed AAAs. And then, the survival rates and rupture rates of AAA between the 2 groups were similar within the following 2 wk (P = 0.487; P = 0.539). Inflammation degree and elastase content in intima media of aneurysms were similar (P = 0.720). However, Tumor necrosis factor alpha and Interleukin-1 beta levels were significantly lower in the novel group than those in the traditional group (P < 0.0001; P < 0.0001). A novel rat AAA model was created by intraluminal elastase infusion through direct puncture the infrarenal aorta. This model is efficient and reliable, with a high survival rate and with similar morphology and histology of aortic aneurysms.

Hu G ，Dong Z ，Fu W 《-》

A novel rat model of abdominal aortic aneurysm using a combination of intraluminal elastase infusion and extraluminal calcium chloride exposure.

Tanaka A ，Hasegawa T ，Chen Z ，Okita Y ，Okada K ... -  《-》

A novel chronic advanced stage abdominal aortic aneurysm murine model.

The purpose of this study was to establish a reliable, chronic model of abdominal aortic aneurysm (AAA). Wild-type 8-week-old C56BL/6 male mice (n = 120) were equally divided into three groups: (1) BAPN group: 0.2% 3-aminopropionitrile fumarate salt (BAPN) drinking water was provided to mice 2 days before surgery until the end of study. Sham aneurysm induction surgery was performed using 5 μL of heat deactivated elastase. (2) Elastase group: mice were given regular drinking water without BAPN. During aneurysm induction surgery, 5 μL of the active form of elastase (10.3 mg protein/mL, 5.9 U/mg protein) was applied on top of the infrarenal abdominal aorta adventitia for 5 minutes. (3) BAPN+elastase group: mice were given BAPN drinking water and the active form of elastase application, as above. On postoperative days 7, 14, 21, 28, and 100, aortic samples were collected for histology, cytokine array, and gelatin zymography after aortic diameter measurement. Compared with the elastase group, the BAPN+elastase group had a higher AAA formation rate (93% vs 65%; P < .01) with more advanced AAAs (25 of 42 vs 1 of 40 for stage II and III; P < .001). Aneurysms from the BAPN+elastase group demonstrated persistent long-term growth (221.5% ± 36.6%, 285.8% ± 78.6%, and 801% ± 160% on days 21, 28, and 100, respectively; P < .001), with considerable thrombus formation (54%) and rupture (31%) at the advanced stages of AAA development. Cytokine levels (pro-matrix metalloproteinase 9, interleukin-1β, interleukin-6, chemokine [C-C motif] ligand 5, triggering receptor expressed on myeloid cells 1, monocyte chemotactic protein 1, and tissue inhibitor of metalloproteinase 1) in the BAPN+elastase group were higher than in the elastase group on day 7. After day 7, cytokine levels returned to baseline, with the exception of elevated matrix metalloproteinase 2 activity. By histology, CD3-positive T cells in the BAPN+elastase group were elevated on days 28 and 100. A combination of oral BAPN administration and periaortic elastase application induced a chronic, advanced-stage AAA with characteristics of persistent aneurysm growth, thrombus formation, and spontaneous rupture. Future studies should use this model, especially for examining tissue remodeling during the late stages of aneurysm development.

Lu G ，Su G ，Davis JP ，Schaheen B ，Downs E ，Roy RJ ，Ailawadi G ，Upchurch GR Jr ... -  《-》

A Modified Murine Abdominal Aortic Aneurysm Rupture Model Using Elastase Perfusion and Angiotensin II Infusion.

The perfused elastase AAA model and subcutaneous Angiotensin II infusion AAA model are widely used murine AAA models. We modified these two current models and developed a new murine model to study aneurysm formation and rupture. The murine abdominal aorta was treated with elastase. Angiotensin II was infused at a dose of 1,000 ng/kg/min via an osmotic pump placed subcutaneously. A saline osmotic pump was used as the control. The aortas were harvested from the mice 4 weeks later, or earlier if mice died. The abdominal aorta was inspected using ultrasound and microscopy for aneurysm formation and/or signs of rupture. The aneurysm outcome was measured using aortic expansion and proinflammatory cytokine expression. It was also compared with the established conventional elastase perfusion and angiotensin II infusion abdominal aortic aneurysm models. By day 28 after surgery, all abdominal aortas of mice treated in the modified group had dilated and progressed to abdominal aortic aneurysms with 60% ruptured aneurysms, whereas none of the control aortas treated with saline became aneurysmal. In mice treated with elastase solution alone, 100% developed aneurysms and only one had a ruptured aneurysm. In mice given angiotensin II infusion alone, 37.5% developed aneurysms and none had a ruptured aneurysm. Histological examination of the modified murine abdominal aortic aneurysm rupture model was identical to that observed in the conventional elastase model. Quantitative polymerase chain reaction analysis revealed similarly increased levels of proinflammatory cytokines. We modified two current murine abdominal aortic aneurysm models to develop a murine abdominal aortic aneurysm model with consistent aneurysm formation and high rupture incidence, which can be used for studying abdominal aortic aneurysm rupture and treatment.

Yue J ，Yin L ，Shen J ，Liu Z ... -  《-》

Serum Calprotectin as a Novel Biomarker in Abdominal Aortic Aneurysm Pathogenesis and Progression: Preliminary Data from Experimental Model in Rats.

Abdominal aortic aneurysm (AAA) formation is associated with by inflammation and matrix degradation. This study tested the hypothesis that calprotectin, a novel biomarker for inflammation, as well as established biomarkers such as C-reactive protein (CRP) and matrix metalloproteinase- 9 (MMP-9) could also be indicative inflammatory biomarkers during AAA pathogenesis and progression. We also evaluated the correlation of serum soluble Receptor for Advanced Glycation End Products (sRAGE) with AAA diameter and serum calprotectin levels. Rat abdominal aortas were perfused with porcine pancreatic elastase (AAA Group) or saline (Control Group) and studied on post-perfusion days 7 and 14 (n=11 per treatment group). Aneurysm was defined as a dilatation of the aorta above 150% of its original diameter. Laparotomy was performed on days 0 (T0), 7 (T7) and 14 (T14) for aortic diameter measurement. At the same time intervals, we measured the serum levels of calprotectin, CRP, sRAGE and MMP-9. All animals developed AAA and no rupture occurred. MMP-9 in AAA group at T14 (p<0.05 compared with T7 and p<0.005 compared with T0) and calprotectin in AAA group at T14 (p<0.001 compared with T7 and T0) continued to significantly increase at all times. Serum sRAGE was significantly lower in the AAA group compared with the control group and within AAA group at all time points (p<0.001). On the other hand, the highest levels of CRP were identified at T7 in both groups. Calprotectin concentrations in AAA group were significantly higher compared with controls at T7 and T14 (p<0.001 and p<0.001, respectively). Aortic diameter was significantly correlated with MMP-9 and calprotectin serum concentrations at all time points (r=0.51, p<0.001; r=0.728, p<0.001 respectively). Serum sRAGE levels were significantly correlated with aortic diameter at all time points (r=-0.48, p<0.001) and serum calprotectin levels (r=-0.22, p<0.001). This is the first evaluation of calprotectin as an AAA inflammation biomarker. It seems to be a promising marker related to AAA natural history. Further experimental and large human studies are needed to fully elucidate the role of calprotectin in the development and progression of AAAs.

Moris D ，Theocharis S ，Davakis S ，Patelis N ，Agrogiannis G ，Vlachos IS ，Spartalis E ，Athanasiou A ，Bakoyiannis C ，Perrea DN ，Georgopoulos S ... -  《-》