Cardiovascular Research Advance Access first published online on May 14, 2009
This version [Corrected Proof] published online on June 8, 2009
Cardiovascular Research, doi:10.1093/cvr/cvp149
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Low-level laser irradiation inhibits abdominal aortic aneurysm progression in apolipoprotein E-deficient mice
1 Department of Anatomy and Cell Biology, The Hebrew University—Hadassah Medical School, PO Box 12272, Jerusalem 91120, Israel
2 Department of Vascular Surgery, The Hebrew University—Hadassah Medical School and University Hospital, Jerusalem, Israel
3 Department of Cardiology, The Hebrew University—Hadassah Medical School and University Hospital, Jerusalem, Israel
4 Department of Veterinary Surgery, The Hebrew University—Hadassah Medical School, Jerusalem, Israel
5 Department of Surgery (Shaarei Zedek Hospital), The Hebrew University—Hadassah Medical School, Jerusalem, Israel
* Corresponding author. Tel: +972 2 675 8422; fax: +972 2 675 7451. E-mail address: gertz{at}cc.huji.ac.il
Aims: Increased early detection of abdominal aortic aneurysm (AAA) and the severe complications of its current treatment have emphasized the need for alternative therapeutic strategies that target pathogenetic mechanisms of progression and rupture. Recent in vitro studies from our laboratory have shown that low-level laser irradiation (LLLI) (780 nm) modifies cellular processes fundamental to aneurysm progression. The present study was designed to determine whether LLLI retards the progression of suprarenal AAA in vivo.
Methods and results: High-frequency ultrasonography (0.01 mm resolution) was used to quantify the effect of LLLI on aneurysmatic aortic dilatation from baseline to 4 weeks after subcutaneous infusion of angiotensin II by osmotic minipumps in the apolipoprotein E-deficient mouse. At 4 weeks, seven of 15 non-irradiated, but none of the 13 LLLI, mice had aneurysmal dilatation in the suprarenal aneurysm-prone segments that had progressed to 
50% increase in maximal cross-sectional diameter (CSD) over baseline (P = 0.005 by Fisher's exact test). The mean CSD of the suprarenal segments (normalized individually to inter-renal control segments) was also significantly lower in irradiated animals (LLLI vs. non-irradiated: 1.32 ± 0.14 vs. 1.82 ± 0.39, P = 0.0002 by unpaired, two-tailed t-test) with a 94% reduction in CSD at 4 weeks compared with baseline. M-mode ultrasound data showed that reduced radial wall velocity seen in non-treated was significantly attenuated in the LLLI mice, suggesting a substantial effect on arterial wall elasticity.
Conclusion: These in vivo studies, together with previous in vitro studies from this laboratory, appear to provide strong evidence in support of a role for LLLI in the attenuation of aneurysm progression. Further studies in large animals would appear to be the next step towards testing the applicability of this technology to the human interventional setting.
KEYWORDS Low-level laser; Apolipoprotein E-deficient mice; Aneurysm; Angiotensin-II; High-frequency ultrasound
Time for review: 18 days