Low-level laser irradiation modulates matrix metalloproteinase activity and gene expression in porcine aortic smooth muscle cells

Background and Objectives The vascular extracellular matrix is maintained by a dynamic balance between matrix synthesis and degradation. This equilibrium is disrupted in arterial pathologies such as abdominal aortic aneurysm. Low‐level laser irradiation (LLLI) promotes wound healing. However, its effect on smooth muscle cells (SMCs), a central player in these responses, has not been established. The current study was designed to determine the effects of LLLI on arterial SMC proliferation, inflammatory markers, and matrix proteins. Study Design/Materials and Methods Porcine primary aortic SMCs were irradiated with a 780 nm laser diode (1 and 2 J/cm2). Trypan blue exclusion assay, immunofluorescent staining for collagen I and III, Sircol assay, gelatin zymography, and RT‐PCR were used to monitor proliferation; collagen trihelix formation; collagen synthesis; matrix metalloproteinase‐2 (MMP‐2) activity, and gene expression of MMP‐1, MMP‐2, tissue inhibitor of MMP‐1 (TIMP‐1), TIMP‐2, and IL‐1‐β, respectively. Results LLLI‐increased SMC proliferation by 16 and 22% (1 and 2 J/cm2, respectively) compared to non‐irradiated cells (P