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Introduction: The current treatment paradigm of abdominal aortic aneurysms (AAA) focuses on observing patients until their disease reaches certain thresholds for intervention, with no preceding treatment available. There is an opportunity to develop drug or cell-based therapies to prevent further aneurysmal growth and decrease the risk of a highly morbid rupture. A previously validated acute AAA swine model was treated directly with gelfoam containing human adipose-derived stem cells (h-ADSCs). Methods: Male Yorkshire swine (n=16) received periadventitial injections (type 1 collagenase and porcine pancreatic elastase) into a 4 cm segment of infrarenal aorta. Experimental group (n=7) received gel foam soaked with 10 million h-ADSCs and control group (n=9) media-soaked gel foam. Aortic diameters (AD) were monitored at post-operative day (POD) 7 and 14 using ultrasound with euthanasia on POD 21. Suprarenal (control) and infrarenal aortas (experimental) were harvested for PCR, mechanical tensiometry testing, histopathological analyses as well as immunohistochemistry (IHC). Each animal served as their own control. Groups were compared with paired t-tests and Mann Whitney U tests. Results: Twelve animals survived until POD 21. Stem cell treated AAAs, unlike controls, demonstrated no growth (-1.6 ± 8.8% vs. 34.8 ± 13.7%, p Conclusion: Stem cell therapy prevents the development of aortic aneurysms in a swine model. Stem cell treated swine with induced AAAs show more normal gross features, histologic, and biochemical properties compared to untreated controls with induced AAAs. Further investigation is merited as a possible translatable therapy for aneurysmal disease.

Introduction: Abdominal aortic aneurysms (AAA) are responsible for over 150,000 deaths worldwide annually. Attempts at producing a reliable large-animal model of AAA have proven challenging. We sought to create a reproducible swine model of AAA using enzymatic degradation of the aortic wall. Methods: A total of 9 male Yorkshire swine received periadventitial injections of type 1 collagenase (23.5 mg) and porcine pancreatic elastase (500 mg) into a 4 cm segment of infrarenal aorta. Aortic diameter growth was monitored at POD 7 and 14 using ultrasound. The animals were euthanized on POD 21, and the suprarenal (control) and infrarenal (treated) aorta was harvested for analysis, after gross measurement of aortic diameter under physiologic blood pressure. Sections of control and treated aorta were used to obtain tensile strength using a tensiometer. Additional segments of the aorta were collected for histopathological analysis (H&E, elastin, alpha smooth muscle actin). PCR of matrix metalloproteinases (MMP9) was conducted. Groups were compared with paired t-tests, or ANOVA for repeated measures, where appropriate. Results: Average percent growth of aortic diameter at POD 21 for treated segments was 27% +/- 16.5% versus 4.5% +/- 4% for control tissue. The average difference in aortic growth by subject, was 26.7% [14.6%-38.8%]; (p Conclusion: A reproducible, large-animal model of AAA, with anatomical, histopathological, and biomechanical properties that are clinically translatable, can be achieved with extraluminal enzymatic degradation.