Influence of low-power laser illumination on pro-inflammatory response in human endothelial cells stimulated with interleukin-1a.

Background: Regarding recent findings on the proven influence of laser light on healing and endothelial regeneration processes, this study was conducted in order to examine the influence of low-power laser illumination on the endothelial inflammatory response. Materials and Methods: Human umbilical vein endothelial cells (HUVECs) isolated from umbilical cord, cultured in standard conditions, were harvested and passaged in 24-well plates. Laser influence on HUVEC inflammatory response was measured by stimulating them with Interleukin-1β (IL-1β) followed by laser light illumination. A 808-nm wave length laser diode and light energy doses of 1.5 and 4.5 J/cm 2 were used (50 mW for 90 and 270 s respectively). The response was measured by assessing Cluster of differentiation 54 (CD54), Cluster of differentiation 62E (CD62E), Monocyte chemotactic protein- 1 (MCP-1) expression and von Willebrand factor (vWF) release, at 6 and 24 h after stimulation. The MCP-1 and vWF activity in cell supernatants was measured with an enzyme- linked immunosorbent assay (ELISA) kit. Cytofluorometry was used to assess CD54 and CD62E expression. Results: MCP-1 concentration in supernatants from HUVECs was significantly lower 6 h after 4.5 J/cm 2 stimulation compared to IL-1β-stimulated cells. No changes in MCP-1 levels after IL-1β stimulation plus 1.5 J/cm 2 illumination, compared to IL-1β stimulated HUVECs were noted. IL-1β stimulation significantly enhanced the concentration of vWF and the expression of CD54 and CD62E. Both energies of laser light illumination inhibited the IL-1β-induced increase of CD54 and CD62E concentration. vWF activity after illumination was comparable to that of unstimulated cells. There were no significant differences in the viable cell count between the