The effects of low level laser therapy on the proliferation of keratinocytes

Abstract

Low-level laser therapy (LLLT) is used clinically to stimulate healing, including re-epitheiialization of wounds. The aim of this study was to investigate (he effects of laser therapy on the proliferation of keratinoeytes. The effects of laser emissions at 632.8 nm (continuous wave) and at 904 nm (200 us 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 keratinoeytes from cultures kept at con Hucncc for several days, Cells from ccmfkscnt and sub-con fluent kcratinocytc cultures were used in order to investigate whether these changes could he reversed more quickly, on subculture, following exposure to laser emission. Keratinoeytes were grown in either 5% or 1% fetal calf serum (FCS), proliferation heing slower in the latter, and the effects of LLLT on them compared. The results obtained indicate that: (1) LLLT stimulates keratinovcte proliferation; (2) the delay in proliferation observed in keratinoeytes taken front confluent cultures may be reduced by iaser 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. © 1993, International Phototherapy Association. All rights reserved.