Arrest of progression of pre-induced abdominal aortic aneurysm in apolipoprotein E-deficient mice by low level laser phototherapy

Background and Objectives Using non‐invasive, high‐frequency ultrasonography (HF‐u/s), we showed that low‐level laser phototherapy (LLL) inhibits de‐novo formation of abdominal aortic aneurysms (AAA) in apolipoprotein‐E‐deficient (Apo‐E‐/‐) mice. The current study tests the effect of LLL on the progression of pre‐induced AAA. Study Design/Material and Methods AAA was induced in Apo‐E‐/‐ mice (age16–20 weeks) by subcutaneous infusion of angiotensin‐II using osmotic minipumps (1000 ng/kg/minutes, 4 weeks). HF‐u/s (40 MHz, 0.01 mm resolution, Vevo‐770, VisualSonics) was used to measure the maximum cross‐sectional‐diameter (MCD) of the suprarenal abdominal aorta, the anterior wall displacement (AWD), and radial wall velocity (RWV). The aortas of mice that developed >35% dilatation at 2 weeks over baseline were exposed retroperitoneally and treated with LLL (780 nm, 2.2 J/cm2, 9 minutes) or sham‐operated. HF‐u/s was repeated at 4 weeks, the mice sacrificed by perfusion fixation, and the aortas excised for histopathology. Results Of all mice with >35% MCD expansion of the suprarenal aorta at 2 weeks, 7(58%) of 12 non‐treated, but only 1(7%) of 14 LLL, had increased MCD(> 1 SD) at 4 weeks (P