Effect of multiple exposures of low-level laser therapy on the cellular responses of wounded human skin fibroblasts

Objective: This study aimed to establish the behavior of wounded human skin fibroblasts (HSF) after heliumneon (HeNe) (632.8 nm) laser irradiation using one, two, or three exposures of different doses, namely, 2.5, 5.0, or 16.0 J/cm(2) on each day for 2 consecutive days.

Conclusion: The results show that the correct energy density or fluence (J/cm(2)) and number of exposures can stimulate cellular responses of wounded fibroblasts and promote cell migration and cell proliferation by stimulating mitochondrial activity and maintaining viability without causing additional stress or damage to the wounded cells. Results indicate that the cumulative effect of lower doses (2.5 or 5 J/cm(2)) determines the stimulatory effect, while multiple exposures at higher doses (16 J/cm(2)) result in an inhibitory effect with more damage.