Stimulatory effect of helium-neon laser irradiation on human umbilical vein endothelial cells

ABSTRACT

Low-level laser irradiation [LLLI] has been shown to modulate the proliferation of endothelial cells. Helium-neon [He-Ne] laser is the best type of laser for biostimulation. The aim of the present study was to investigate the direct stimulatory effect of LLLI on the proliferative potential of human umbilical vein endothelial cell line in vitro. This study included five groups group I [zero time after seeding He-Ne laser irradiation], group II [24 h after seeding He-Ne laser irradiation], group III [48 h after seeding He-Ne laser irradiation], group IV [96 h after seeding He-Ne laser irradiation], and group V [cumulative He-Ne laser irradiation every 48 h for a period of 6 days]. Each group was subdivided into three subgroups subgroup a [control], subgroup b [1.77 J/cm[2]He-Ne laser irradiation], and subgroup c [3.54 J/cm[2] He-Ne laser irradiation]. A continuous wave He-Ne laser, emitting a wavelength of 632.8 nm with a power output of 5 mW was used for irradiating the cells. A growth curve was constructed for each group to determine the growth parameters. The most efficient cellular response to LLLI was in subgroup Ic depending on the population doublings achieved, followed by subgroup Ib. Therefore, the early the use of He-Ne laser irradiation for the cultured cells, the more the cellular stimulation and proliferation. Meanwhile, their delayed use resulted in less cellular stimulation and proliferation. Moreover, the results showed that 1.77 and 3.54 J/cm[2] of He-Ne laser irradiation were always stimulatory for endothelial cells either significantly or insignificantly. The present study showed that 1.77 and 3.54 J/cm[2] of He-Ne laser irradiation stimulated human umbilical vein endothelial cell line proliferation