Effect of low-level laser therapy on mast cells in second-degree burns in rats

Mast cells have been shown to participate in the
wound healing process. We investigated the effects of low-level
laser therapy (LLLT) on mast cell number in the inflammation,
proliferation, and remodeling phases of the wound healing process
of experimental burns. Sixty rats subjected to third-degree
burns were divided into four groups: two laser-treated, one control,
and one nitrofurazone-treated group. In the two lasertreated
groups, burned areas received LLLT with a helium-neon
laser at energy densities of 38.2 J/cm2 and 76.4 J/cm2, respectively.
The effects on mast cell number and degranulation were
assessed 7, 16, and 30 days postburn (inflammation, proliferation,
and remodeling phases of wound healing, respectively).
Intact and degranulated mast cells were counted. Five rats with
no burns were used for baseline studies. On day 7 in the first
laser group, the total number of mast cells was significantly
higher than in the other groups. On day 16 in the nitrofurazonetreated
group, the total number of mast cells was significantly
higher than in the control, first laser, and normal groups. LLLT
on the experimental third-degree burns significantly increased
the total number of mast cells during the inflammation phase of
wound healing; also, topical application of 0.2% nitrofurazone
ointment on the same burns significantly increased the total
number of mast cells during the proliferation phase of burn
healing.