Novel experimental model of enlarging abdominal aortic aneurysm in rabbits

Decellularized adipose matrix hydrogel-based in situ delivery of antagomiR-150-5p for rat abdominal aortic aneurysm therapy

Abdominal aortic aneurysm (AAA) is a progressive aortic disease featured by inflammation, vascular smooth muscle cells (VSMCs) depletion, and elastin degradation. MicroRNAs were related to AAA formation, which bring the approach for precise and targeted drug therapy for AAA. We developed a new strategy based on decellularized adipose matrix (DAM) hydrogel immobilized on the adventitia to release antagomiR-150-5p for preventing the AAA development. In this study, Cacl2-induced and elastase-induced rat AAA models were established. We found that miR-150-5p was upregulated while Notch3 was downregulated in two rat AAA models. Then a mold was designed for shaping hydrogel for miR-150-5p delivery around the abdominal aorta. Interestingly, inhibition of miR-150-5p in AAA by local release of antagomiR-150-5p with DAM hydrogel significantly prevented aortic dilation and elastin degradation. Moreover, inflammatory cell infiltration, the expression of inflammatory cytokines (MCP-1, TNF-α, and NF-κB (p65)), and matrix metalloproteinases (MMP-2, MMP-9) were increased while Notch3 and α-SMA were decreased in rat AAA, which can be attenuated by antagomiR-150-5p treatment. In VSMCs with TNF-α stimulation, we further demonstrated that inhibition of miR-150-5p downregulated NF-κB (p65), MMP-2, and MMP-9 and upregulated elastin via Notch3. This work presents a translational potential strategy for AAA repair via DAM hydrogel sustained release of antagomiR-150-5p, and highlights the mechanism of miR-150-5p during AAA progression by regulating Notch3.

A Novel Method for the Rat Model of Abdominal Aortic Aneurysm Induced by Retroperitoneal Implantation of an Osmotic Pump System With Lipopolysaccharide

BACKGROUND

Few methods can cocurrently mimic the pathological characteristics and nature history of human abdominal aortic aneurysms (AAAs), especially for the exist of the self-healing tendency of rodents. This study tested a novel method for the AAA rat model induced by retroperitoneal implantation of an osmotic pump system with lipopolysaccharide (LPS) based on the hypothesis that chronic inflammation of perivascular adipose tissue directly influenced the development and progression of AAAs.

METHODS

20 male Sprague-Dawley rats (10-month-old) fed with the Paigen diet were randomly divided into 4 groups: the blank group ×2, the sham group ×4, the empty capsule group ×4, and the LPS capsule group ×10. The LPS capsule group received implantations of the ALZET® osmotic pump capsule with LPS (3.6 μg/day) parallel to the abdominal aorta through a retroperitoneal approach. Two weeks later, 6 rats were randomly selected from the LPS capsule group to form the anti-inflammatory group and received implantations of another osmotic pump capsule with interleukin (IL)-10 (75 ng/day) through the same approach. The changes in abdominal aortic diameter were observed by ultrasound every 2 weeks, and samples were harvested for histopathologic and immunohistochemical analysis 6 weeks later.

RESULTS

Within the 6 weeks after modeling, the LPS capsule group showed sustained and significant aortic dilatation (P < 0.01), while the anti-inflammatory group showed a rapid and obvious shrinkage 2 weeks after the IL-10 osmotic pump capsule implantation (P < 0.01). The LPS capsule group presented excellent pathological mimicking of human AAAs and showed severe medial degeneration with the least elastic content among the 5 groups at the end of the sixth week (P < 0.05). Notably, the anti-inflammatory group showed perfect medial preservation with the most elastic content (P < 0.05) and the highest elastin/collagen ratio (P < 0.01) at the end of the study. Matrix metalloproteinases (MMP) 2 and 9 and toll-like receptor 2 showed strong expression in the LPS capsule group at the end of the sixth week, which was significantly higher than that in the blank group and sham group. Interestingly, the anti-inflammatory group showed a slightly higher MMP9 expression than the LPS capsule group though there was no statistical difference between them.

CONCLUSIONS

This novel method for the rat AAA model induced by retroperitoneal implantation of an osmotic pump capsule with LPS can concurrently mimic the histological characteristics and natural history of human AAAs. Further studies were needed to improve the osmotic pump system.

Disturbed flow's impact on cellular changes indicative of vascular aneurysm initiation, expansion, and rupture: A pathological and methodological review

Aneurysms are malformations within the arterial vasculature brought on by the structural breakdown of the microarchitecture of the vessel wall, with aneurysms posing serious health risks in the event of their rupture. Blood flow within vessels is generally laminar with high, unidirectional wall shear stressors that modulate vascular endothelial cell functionality and regulate vascular smooth muscle cells. However, altered vascular geometry induced by bifurcations, significant curvature, stenosis, or clinical interventions can alter the flow, generating low stressor disturbed flow patterns. Disturbed flow is associated with altered cellular morphology, upregulated expression of proteins modulating inflammation, decreased regulation of vascular permeability, degraded extracellular matrix, and heightened cellular apoptosis. The understanding of the effects disturbed flow has on the cellular cascades which initiate aneurysms and promote their subsequent growth can further elucidate the nature of this complex pathology. This review summarizes the current knowledge about the disturbed flow and its relation to aneurysm pathology, the methods used to investigate these relations, as well as how such knowledge has impacted clinical treatment methodologies. This information can contribute to the understanding of the development, growth, and rupture of aneurysms and help develop novel research and aneurysmal treatment techniques.

Degeneration and Regeneration of Smooth Muscle Cells in Two Different Abdominal Aortic Aneurysm Models in Rabbits

BACKGROUND

We aimed to investigate the formation and self-healing process of rabbit abdominal aortic aneurysm (AAA) by focus on the degeneration and regeneration of smooth muscle cells (SMCs) in elastase-induced AAA model and enlarging AAA model in rabbits.

METHODS

Sixty rabbits were equally divided into 2 aneurysm groups (Group A and Group B). Rabbits received a 10-min incubation of elastase in Group A (10 units/µL) and Group B (1 unit/µL). Rabbits underwent aortic stenosis above the incubated segment in Group B. Aortic diameter was measured and rabbits were sacrificed for histopathological and immunohistochemical studies.

RESULTS

The incubated aorta dilated immediately and ran up to maxima by day 21 in Group A. All aneurysms formed by day 21 and enlarged progressively in Group B. SMCs content, elastin content and intima-media thickness decreased significantly by day 0 in Group A. SMCs and elastic fibers were destroyed gradually in Group B, however, SMCs content was significantly lower than Group A by day 70. Intimal thickness increased significantly by day 70 in the Aneurysm groups. MMP2 maintained moderate expression in Group A, which decreased significantly by day 3 in Group B. MMP9 and RAM11 expressions were higher by day 1, but decreased significantly by day 3 in Group B.

CONCLUSIONS

Irreversible degeneration of SMCs is critical to a rapid formation of elastase-induced rabbit AAA model, and SMCs excessive regeneration accounts for the selfhealing process. SMCs degradation and regeneration remain relatively stable in an enlarging AAA model. SMCs should be the key target for studying the mechanism of AAA and intervention therapy.

Smoking and the Pathophysiology of Peripheral Artery Disease

Smoking is one of the most important preventable factors causing peripheral artery disease (PAD). The purpose of this review is to comprehensively analyze and summarize the pathogenesis and clinical characteristics of smoking in PAD based on existing clinical, in vivo, and in vitro studies. Extensive searches and literature reviews have shown that a large amount of data exists on the pathological process underlying the effects of cigarette smoke and its components on PAD through various mechanisms. Cigarette smoke extracts (CSE) induce endothelial cell dysfunction, smooth muscle cell remodeling and macrophage phenotypic transformation through multiple molecular mechanisms. These pathological changes are the molecular basis for the occurrence and development of peripheral vascular diseases. With few discussions on the topic, we will summarize recent insights into the effect of smoking on regulating PAD through multiple pathways and its possible pathogenic mechanism.

MiR-126-5p promotes contractile switching of aortic smooth muscle cells by targeting VEPH1 and alleviates Ang II-induced abdominal aortic aneurysm in mice

Abdominal aortic aneurysm (AAA) is a potential lethal disease that is defined by an irreversible dilatation (>50%) of the aorta. During AAA expansion, the aortic wall is often remodeled, which is featured by extracellular matrix (ECM) degeneration, medial and adventitial inflammation, depletion and phenotypic switching of vascular smooth muscle cells (SMCs). Recent studies have suggested microRNAs as vital regulators for vascular SMC function. Our earlier work demonstrated an anti-AAA role of miR-126-5p in ApoE^-/- mice infused with angiotensin (Ang) II. The present study aimed to further elucidate its role in AAA pathogenesis with a focus on aortic SMC phenotypic switching. Ventricular zone expressed PH domain containing 1 (VEPH1) was identified as a novel negative regulator for vascular SMC differentiation by our group, and its expression was negatively correlated to miR-126-5p in mouse abdominal aortas based on the present microarray data. In vivo, in addition attenuating Ang II infusion-induced aortic dilation and elastin degradation, miR-126-5p agomirs also significantly reduced the expression of VEPH1. In vitro, to induce synthetic transition of human aortic smooth muscle cells (hAoSMCs), cells were stimulated with 1 μM Ang II for 24 h. Ectopic overexpression of miR-126-5p restored the differentiation of hAoSMCs-the expression of contractile/differentiated SMC markers, MYH11, and α-SMA, increased, whilst that of synthetic/dedifferentiated SMC markers, PCNA and Vimentin, decreased. Both mus and homo VEPH1 genes were validated as direct targets for miR-126-5p. VEPH1 re-expression impaired miR-126-5p-induced differentiation of hAoSMCs. In addition, Ang II-induced upregulation in matrix metalloproteinase (MMP)-9 and MMP2, two key proteases responsible for ECM degradation, in mouse aortas and hAoSMCs was reduced by miR-126-5p overexpression as well. Collectively, these results reveal an important, but previously unexplored, role of miR-126-5p in inhibiting AAA development-associated aortic SMC dedifferentiation.

Hemodynamics and pathology of an enlarging abdominal aortic aneurysm model in rabbits

Hemodynamics may play an essential role in the initiation and progression of abdominal aortic aneurysm (AAA). We aimed to study the mechanism of self-healing process by the changes of hemodynamics and pathology in an enlarging AAA in rabbits. Seventy-two rabbits were randomly divided into three groups. Rabbits underwent extrinsic coarctation and received a 10-minute elastase incubation in Group A and Group B. Absorbable suture used in Group A was terminated by balloon dilation at week 4. Diameter was measured after 1, 3, 5, and 15 weeks, computational fluid dynamics analysis was performed at week 3 and week 15. Rabbits were sacrificed after 1, 5, and 15 weeks for pathological and quantitative studies. The higher velocity magnitude, intensified bulk flow and obvious vortex formation were observed in Group A at week 3 instead of week 15. Both low wall shear stress and high relative residence time increased in Group B, however, high oscillatory shear index had relatively less increase compared with Group A. Aortic diameter reached a plateau at 5 weeks in Group A, which was significantly lower than in week 15 in Group B. Intimal hyperplasia, intima-media thickness increased significantly in Group A at week 5, significantly higher than in week 15 in Group B. Marked destruction of elastin fibers and smooth muscle cells occurred at week 1, and increased significantly at week 15 in Group A. Aneurysm exhibited strong expression of matrix metalloproteinase 9 and mouse anti-rabbit macrophage 11 at week 1, and showed a tendency to decrease. Matrix metalloproteinase 2 expression decreased significantly in Group B at week 15 compared with week 5 and Group A. In conclusion, the self-healing of rabbit AAA may attributed to the regeneration of smooth muscle cells. The turbulence flow caused by coarctation is associated with continuous growth of rabbit AAA and prevents the self-healing phenomenon.

Comprehensive intravascular imaging of atherosclerotic plaque in vivo using optical coherence tomography and fluorescence lifetime imaging

Comprehensive imaging of both the structural and biochemical characteristics of atherosclerotic plaque is essential for the diagnosis and study of coronary artery disease because both a plaque's morphology and its biochemical composition affect the level of risk it poses. Optical coherence tomography (OCT) and fluorescence lifetime imaging (FLIm) are promising optical imaging methods for characterizing coronary artery plaques morphologically and biochemically, respectively. In this study, we present a hybrid intravascular imaging device, including a custom-built OCT/FLIm system, a hybrid optical rotary joint, and an imaging catheter, to visualize the structure and biochemical composition of the plaque in an atherosclerotic rabbit artery in vivo. Especially, the autofluorescence lifetime of the endogenous tissue molecules can be used to characterize the biochemical composition; thus no exogenous contrast agent is required. Also, the physical properties of the imaging catheter and the imaging procedures are similar to those already used clinically, facilitating rapid translation into clinical use. This new intravascular imaging catheter can open up new opportunities for clinicians and researchers to investigate and diagnose coronary artery disease by simultaneously providing tissue microstructure and biochemical composition data in vivo without the use of exogenous contrast agent.

Rabbit aortic aneurysm model with enlarging diameter capable of better mimicking human aortic aneurysm disease

The self-healing phenomenon can be found in the elastase-induced abdominal aortic aneurysm (AAA) model, and an enlarging AAA model was successfully induced by coarctation. Unfortunately, aortic coarctation in these enlarging models is generally not found in human AAA disease. This study aimed to create an experiment model of enlarging AAA in rabbits to better mimic human aortic aneurysm disease. Eighty-four male New Zealand white rabbits were randomly divided into three equal groups: two aneurysm groups (A and B) and a SHAM group. Aneurysm group rabbits underwent extrinsic aortic stenosis below the right renal artery and received a 10-minute incubation of 60 μl elastase (1 unit/μl). Absorbable suture was used in Group A and nonabsorbable cotton thread was used in Group B. A sham operation was performed in the SHAM group. Aortic diameter was measured after 1, 3, 7, and 15 weeks; thereafter animals were sacrificed for histopathological, immunohistochemical and quantitative studies. Two rabbits died at 29 and 48 days, respectively, after operation in Group B. All aneurysms formed and enlarged progressively by 3 weeks in the Aneurysm groups. However, diameter enlargement in Group A was significantly lower than that in Group B at 7 weeks. Aneurysm groups developed intimal hyperplasia; intima-media thickness (IMT) increased significantly by week 7, and aortic media thickness and intima-media ratio (IMR) increased significantly by week 15. Marked destruction of elastin fibers and smooth muscle cells (SMCs) occurred 1 week later and increased progressively thereafter. Intimal hyperplasia and SMCs content in Group A increased significantly by week 15 compared with Group B. Aneurysm groups exhibited strong expression of matrix metalloproteinases 2 and 9 and RAM11 by week 1, and decreased progressively thereafter. In conclusion, this novel rabbit AAA model enlarges progressively without coarctation and is capable of better mimicking human aortic aneurysm disease.

Animal Models in the Research of Abdominal Aortic Aneurysms Development

Abdominal aortic aneurysm (AAA) is a prevalent and potentially life threatening disease. Many animal models have been developed to simulate the natural history of the disease or test preclinical endovascular devices and surgical procedures. The aim of this review is to describe different methods of AAA induction in animal models and report on the effectiveness of the methods described in inducing an analogue of a human AAA. The PubMed database was searched for publications with titles containing the following terms “animal” or ‘‘animal model(s)’’ and keywords “research”, “aneurysm(s)’’, “aorta”, “pancreatic elastase’’, “Angiotensin”, “AngII” “calcium chloride” or “CaCl2”. Starting date for this search was set to 2004, since previously bibliography was already covered by the review of Daugherty and Cassis (2004). We focused on animal studies that reported a model of aneurysm development and progression. A number of different approaches of AAA induction in animal models has been developed, used and combined since the first report in the 1960’s. Although specific methods are successful in AAA induction in animal models, it is necessary that these methods and their respective results are in line with the pathophysiology and the mechanisms involved in human AAA development. A researcher should know the advantages/disadvantages of each animal model and choose the appropriate model.

Inhibition of Phosphatidylinositol 3-kinease suppresses formation and progression of experimental abdominal aortic aneurysms

Accumulating evidence suggests an important role of Phosphatidylinositol 3-kinease (PI3K) pathway in inflammatory cells infiltration. Given  the essential role of inflammatory cells infiltration during the formation and progression of abdominal aortic aneurysm (AAA), to investigate the possibility of preventing AAA formation and progression via targeting PI3K is anticipated. Here, experimental AAAs was created in rats by transient intraluminal porcine pancreatic elastase (PPE) infusion into the infrarenal aorta firstly. AAAs rats were administrated with vehicle or Wortmannin during the period of day 0 to day 28 after PPE infusion. The aortic diameter of rats treated with Wortmannin was significantly smaller than those treated with vehicle. Meanwhile, Elastin destruction score and SMC destruction score were significantly decreased in rats treated with Wortmannin. Furthermore, histological analysis revealed infiltration of inflammatory cells were significantly reduced in rats treated with Wortmannin. Finally, the mRNA expression of PI3K and protein expression of pAKT in human abdominal aneurismal aorta tissues was elevated as compare to normal aorta. Our study revealed that PI3K inhibitor suppresses experimental AAAs formation and progression, through mechanisms likely related to impairing inflammation cells infiltration and median elastin degradation. These findings indicated that PI3K inhibitor may hold substantial translation value for AAA diseases.

Transauricular intra-arterial and intravenous digital subtraction angiography for abdominal aortic aneurysm imaging in a rabbit model

Aim

The aim of this study was to evaluate transauricular digital subtraction angiography (DSA) as an alternative to conventional intra-arterial DSA for rabbit abdominal aortic aneurysm (AAA).

Materials and methods

AAA models were created in 8 New Zealand white rabbits by sewing vein patch. The diameters of aortic arteries were measured by DSA via ear vein and ear central artery. The common carotid artery (CCA) was exposed and cannulated for DSA as conventional angiography. Diameter size was measured and compared.

Results

Aortic diameters, tested by DSA via ear vein, ear central artery and CCA were 7.9 ± 1.2 mm, 7.8 ± 1.0 mm and 7.9 ± 1.1 mm respectively, with no significant differences. Angiography via CCA as standard procedure, correlation in aneurysm neck diameter was r = 0.93 for IVDSA and r = 0.96 for angiography via central artery (P < 0.01); Correlation in AAA diameter was r = 0.99 for IVDSA and r = 0.99 for angiography via central artery (P < 0.0001).

Conclusions

Transauricular DSA shows good correlation to conventional DSA, can be used repeatedly with less invasiveness, and suitable for rabbit AAA follow-up study.

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Correlations of DSA via ear vein and ear central artery to conventional DSA were good.

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Transauricular DSA shows good correlation to conventional DSA.

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Transauricular DSA can be used repeatedly with less invasiveness, and suitable for rabbit AAA follow-up study.

Effect of Low-Pressurized Perfusion with Different Concentration of Elastase on the Aneurysm Formation Rate in the Abdominal Aortic Aneurysm Model in Rabbits

Establishing an animal model of abdominal aortic aneurysm (AAA) is the key to study the pathogenesis and the pathophysiological features of AAAs. We investigated the effects of low-pressurized perfusion with different concentrations of elastase on aneurysm formation rate in the AAA model. Fifty male New Zealand white rabbits were randomly divided into A, B, C, D, and E groups. 10 μL of normal saline was perfused into the abdominal aorta in group A and 1 U/mL, 10 U/mL, 100 U/mL, or 200 U/mL of elastase was, respectively, perfused for the other four groups. All the animals were perfused for 7 min. Doppler ultrasound examinations of the abdominal aorta were performed before surgery and on day 14 after surgery. The rabbits were sacrificed and the perfused segment of the abdominal aorta was observed visually and after staining. The aneurysm formation rate of group A, group B, group C, group D, and group E was, respectively, 0%, 0%, 33.3%, 102.5–146.8%, and 241.5–255.2%. The survival rate of five groups was 90%, 90%, 90%, 90%, and 40%, respectively. So, we concluded that low-pressurized perfusion with 100 U/mL of elastase can effectively establish AAAs in rabbits with a high aneurysm formation rate.

Tauroursodeoxycholic Acid Attenuates Angiotensin II Induced Abdominal Aortic Aneurysm Formation in Apolipoprotein E-deficient Mice by Inhibiting Endoplasmic Reticulum Stress

OBJECTIVE/BACKGROUND

Abdominal aortic aneurysm (AAA) is characterised by the infiltration of smooth muscle cell (SMC) apoptosis, inflammatory cells, neovascularisation, and degradation of the extracellular matrix. Previous work has shown that endoplasmic reticulum (ER) stress and SMC apoptosis were increased both in a mouse model and human thoracic aortic aneurysm. However, whether the ER stress is activated in AAA formation and whether suppressing ER stress attenuates AAA is unknown.

METHODS

Human AAA and control aorta samples were collected. Expression of ER stress chaperones glucose-regulated protein (GRP)-78 and GRP-94 was detected by immunohistochemical staining. The effect of ER stress inhibitor tauroursodeoxycholic acid (TUDCA) on AAA formation in angiotensin (Ang) II induced apolipoprotein E^-/- mice was explored. Elastin staining was used to observe the rupture of elastic fragmentation. Immunohistochemistry and Western blot analysis were performed, to detect the protein expression of ER stress chaperones and apoptosis molecules.

RESULTS

There was significant upregulation of GRP-78 and GRP-94 in aneurysmal areas of human AAA and Ang II induced ApoE^-/- mice (p < .05). TUDCA significantly attenuated the maximum diameters of abdominal aortas in Ang II induced ApoE^-/- mice (p < .05). TUDCA significantly reduced expression of ER stress chaperones and the apoptotic cell numbers (p < .05). Furthermore, TUDCA significantly reduced expression of apoptosis molecules, such as caspase-3, caspase-12, C/EBP homologous protein, c-Jun N-terminal kinase activating transcription factor 4, X-box binding protein, and eukaryotic initiation factor 2α in Ang II induced ApoE^-/- mice (p < .05).

CONCLUSION

The results suggest that ER stress is involved in human and Ang II induced AAA formation in ApoE^-/- mice. TUDCA attenuates Ang II induced AAA formation in ApoE^-/- mice by inhibiting ER stress mediated apoptosis.

Inhibition of early AAA formation by aortic intraluminal pentagalloyl glucose (PGG) infusion in a novel porcine AAA model

Background

The vast majority of abdominal aortic aneurysms found in screening programs are small, and as no effective treatment exits, many will expand until surgery is indicated. Therefore, it remains intriguing to develop a safe and low cost treatment of these small aneurysms, that is able to prevent or delay their expansion.

In this study, we investigated whether intraluminal delivered pentagalloyl glucose (PGG) can impair the early AAA development in a porcine model.

Methods

The infrarenal aorta was exposed in thirty pigs. Twenty underwent an elastase based AAA inducing procedure and ten of these received an additional intraluminal PGG infusion. The final 10 were sham operated and served as controls.

Results

All pigs who only had an elastase infusion developed macroscopically expanding AAAs. In pigs treated with an additional PGG infusion the growth rate of the AP-diameter rapidly returned to physiological values as seen in the control group. In the elastase group, histology revealed more or less complete resolution of the elastic lamellae in the media while they were more abundant, coherent and structurally organized in the PGG group. The control group displayed normal physiological growth and histology.

Conclusion

In our model, intraluminal delivered PGG is able to penetrate the aortic wall from the inside and impair the early AAA development by stabilizing the elastic lamellae and preserving their integrity. The principle holds a high clinical potential if it can be translated to human conditions, since it, if so, potentially could represent a new drug for stabilizing small abdominal aneurysms.

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Pentagalloyl glucose impairs the early AAA development in a porcine model.

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Pentagalloyl glucose stabilizes arterial elastic lamellae and preserves their integrity.

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Pentagalloyl glucose can penetrate the arterial wall in large AAA prone arteries from the inside.

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Pentagalloyl glucose, a potential new drug for stabilizing small abdominal aneurysms.

Interference of doxycycline pretreatment in a model of abdominal aortic aneurysms

BACKGROUND

Abdominal aortic aneurysm (AAA) is characterized by chronic inflammation and degradation of the extracellular matrix, mediated by matrix metalloproteinases (MMPs). Doxycycline has been reported to control the progression of AAA by regulation of MMP. We hypothesized that doxycycline pretreatment in a rat model of AAA would cause reduction in gelatinolytic activity of MMP-2 and -9 and the inflammatory response in the wall of an aneurysm, consequently decreasing the formation and development of AAAs.

METHODS

Male Wistar rats were divided into the following four groups: aneurysm (A); control (C); aneurysm+doxycycline (A+D) and control+doxycycline (C+D), with 24 animals per group subdivided into n=6 animals at different time points [1, 3, 7, and 15 days postsurgery (dps)]. The (A) and (A+D) groups simultaneously received the injury and extrinsic stenosis of the aortic wall. The (C) and (C+D) groups received sham operation. The treated animals received doxycycline via gavage (30 mg/kg/day) from 48 h before surgery until the end of experiment. At 1, 3, 7, and 15 dps, the animals were euthanized, and the aortas were collected for morphological analyses, immunohistochemistry, and zymography.

RESULTS

The animals from the (A) group developed AAAs. However, the animals treated with doxycycline showed a 85% decrease in AAA development, which was associated with a large reduction in gelatinolytic activity of MMP-2 and -9, and decreased inflammatory response (P<.05).

CONCLUSIONS

These results suggest that pretreatment with doxycycline before surgery inhibited the activity of MMP-2 and -9, as well as the inflammatory response, and may play an important role in the prevention of the development of AAAs.