An in vitro method to test the safety and efficacy of low-level laser therapy (LLLT) in the healing of a canine skin model

Abstract

BackgroundLow-level laser therapy (LLLT) has been used clinically as a treatment modality for a variety of medical conditions including wound-healing processes. It is an attractive and emerging method to enhance wound healing and improve clinical outcomes both in human and veterinary medicine. Despite the fact that the use of LLLT continues to gain in popularity, there is no universally accepted theory that defends all its cellular effects and beneficial biological processes in tissue repair. The present study was designed to evaluate the effect of LLLT on cellular migration and proliferation of cultured canine epidermal keratinocytes (CPEK) in an in vitro wound healing model.ResultsKeratinocyte migration and proliferation were assessed using a scratch migration assay and a proliferation assay, respectively. Fifteen independent replicates were performed for each assay. Canine epidermal keratinocyte cells exposed to LLLT with 0.1, 0.2, and 1.2 J/cm2 migrated significantly more rapidly (p < 0.03) and showed significantly higher rates of proliferation (p < 0.0001) compared to non-irradiated cells cultured in the same medium and cells exposed to the higher energy dose of 10 J/cm2. Irradiation with 10 J/cm2 was characterized by decreased cellular migration and proliferation. These results revealed that LLLT has a measurable, dose-dependent effect on two different aspects of keratinocyte biology in vitro.ConclusionIn this in vitro wound-healing model, LLLT increased cellular migration and proliferation at doses of 0.1, 0.2, and 1.2 J/cm2 while exposure to 10 J/cm2 decreased cellular migration and proliferation. These data suggest that the beneficial effects of LLLT in vivo may be due, in part, to effects on keratinocyte behavior.

Effects of low‐level laser therapy on the healing of surgically closed incisions and surgically created open wounds in dogs

“…The ideal laser energy density (J/cm 2 ) and treatment frequency delivered to incisions and wounds are unknown. Lower energy settings may not have any remedial effect on the wound; however, higher energy settings have been shown to be detrimental to wound healing . Authors of in vitro studies using human fibroblasts and in vivo studies assessing rat wounds have suggested that 0.5‐5 J/cm 2 stimulates healing, whereas >10 J/cm 2 may be inhibitory .…”

“…Authors of in vitro studies using human fibroblasts and in vivo studies assessing rat wounds have suggested that 0.5‐5 J/cm 2 stimulates healing, whereas >10 J/cm 2 may be inhibitory . Using canine keratinocytes, authors of a recent in vitro study found increased cellular migration and proliferation at 0.1, 0.2, and 1.2 J/cm 2 and detrimental effects at 10 J/cm 2 . It is not known how these findings translate into in vivo healing because of the many variables that could affect healing.…”

“…Promising results have been achieved in vitro, demonstrating an increase in human fibroblast migration, cell viability, increased collagen production, decreased inflammatory cytokine production, and decreased apoptosis . A recent study that used canine epidermal keratinocytes in culture suggested an increased migration and proliferation when cells were exposed to LLLT at 0.1, 0.2, or 1.2 J/cm 2 but saw detrimental effects at 10 J/cm 2 …”

The effects of different 650 nm laser diode irradiation times on the viability and proliferation of human periodontal ligament fibroblast cells

“…10 Lasers are known to induce biphasic dose responses (BDR), namely; biostimulation and bioinhibition responses. 11 This effect is related to an increase in adenosine triphosphate (ATP) in the mitochondria that produce deoxyribonucleic acid (DNA) and ribose nucleic acid (RNA) and whose synthesis increases after laser diode irradiation. This increase can cause cellular responses to injury through the production of proteins associated with repair and healing processes.…”

Uso do laser de baixa potência em estrias de distensão: ensaio clínico randomizado controlado

“…A laserterapia de baixa intensidade já é reconhecida como um método de tratamento eficaz para cicatrização de tecidos. Vários estudos in vitro e in vivo têm mostrado ações positivas na perfusão tecidual e estimulo à neovascularização, proliferação fibroblástica e queratinócitos, aumento na síntese e deposição de colágeno e hidroxiprolina, diminuição de mediadores inflamatórios como IL-1β, IL-10, TNF-α e NF-κB, diminuição do estresse oxidativo e aceleração da cura tecidual [7,9,[12][13][14][15].…”