Direct stimulatory effect of low-intensity 670 nm laser irradiation on human endothelial cell proliferation.

Background: Endothelial cell (EC) proliferation plays a key role in the process of tissue repair. Low-intensity laser irradiation has been demonstrated to accelerate wound healing and to improve microvascularization.

Objectives: The present study evaluated a possible stimulatory influence of low-intensity laser irradiation on human umbilical vein endothelial cell (HUVEC) proliferation in a systematic manner.

Methods: Subconfluent cultures of HUVEC were irradiated every other day with a 670-nm diode laser (intensity: 10-65 mW cm(-2), dose: 2-8 J cm(-2)) during a period of 6 days. Cell proliferation was evaluated quantitatively by counting in a haemocytometer.

Results: Our data demonstrate a dose-dependent and intensity-dependent stimulatory effect of laser irradiation on HUVEC cell proliferation. Doses of between 2 and 8 J cm(-2) induced statistically significant cell proliferation. Testing different intensities at a constant dose of 8 J cm(-2), 20 and 65 mW cm(-2) induced most pronounced cell proliferation.

Conclusions: Low-intensity laser irradiation influences EC proliferation and might thereby contribute to the increase in angiogenesis and the acceleration of wound healing in vivo.