Abstract
Low-level laser therapy (LLLT) is used clinically to stimulate healing, including re-epithelialization of wounds. The aim of this study was to investigate the effects of laser therapy on the proliferation of keratinocytes. The effects of laser emissions at 632.8 nm (continuous wave) and at 904 nm (200 ns pulses at frequencies of 1205 pps and 3125 pps) at energy densities of 0.25-4 J/cm2 were investigated.
Phenotypic alterations have been noted in keratinocytes from cultures kept at confluence for several days. Cells from confluent and sub-confluent keratinocyte cultures were used in order to investigate whether these changes could be reversed more quickly, on subculture, following exposure to laser emission. Keratinocytes were grown in either 5% or 1% fetal calf serum (FCS), proliferation being slower in the latter, and the effects of LLLT on them compared.
The results obtained indicate that: (1) LLLT stimulates keratinoycte proliferation; (2) the delay in proliferation observed in keratinocytes taken from confluent cultures may be reduced by laser irradiation; (3) LLLT has a greater effect on cultures grown in the poor conditions of 1% FCS than in the better conditions provided by 5% FCS; and (4) LLLT has biostimulatory properties at energy densities as low as 0.25 J/cm2.
