Articles

Low-Level Light Stimulates Excisional Wound Healing in Mice

Demidova-Rice, T.N., Salomatina, E.V., Yaroslavsky, A.N.

Lasers in Surgery and Medicine 2007

39: 706-715

Background: Low levels of laser or non-coherent light, termed low-level laser therapy (LLLT) have been reported to accelerate some phases of wound healing but its clinical use remains controversial.

Methods: A full thickness dorsal excisional wound in mice was treated with a single exposure to light of various wavelengths and fluences 30 minutes after wounding. Wound areas were measured until complete healing and immunofluorescence staining of tissue samples was carried out.

Results: Wound healing was significantly stimulated in BALB/c and SKH1 hairless mice but not in C57BL/6 mice. Illuminated wounds started to contract while control wounds initially expanded for the first 24 hours. We found a biphasic dose – response curve for fluence of 635-nm light with a maximum positive effect at 2 J/cm². Eight hundred twenty nanometer was found to be the best wavelength tested compared to 635, 670 and 720 nm. We found no difference between non-coherent 635 ± 15-nm light from a lamp and coherent 633-nm light from a HeNe laser. LLLT increased the number of α-smooth muscle actin (SMA)-positive cells at the wound edge.

Conclusions: LLLT stimulates wound contraction in susceptible mouse strains but the mechanism remains uncertain.