The role of laser fluence in cell viability, proliferation, and membrane integrity of wounded human skin fibroblasts following helium‐neon laser irradiation

Abstract

Background: In medicine, lasers have been used predominantly for applications, which are broadly termed low level laser therapy (LLLT), phototherapy or photobiomodulation. This study aimed to establish cellular responses to Helium-Neon (632.8 nm) laser irradiation using different laser fluences (0.5, 2.5, 5, 10, and 16 J/cm 2 ) with a single exposure on 2 consecutive days on normal and wounded human skin fibroblasts. Materials and Methods: Changes in normal and wounded fibroblast cell morphology were evaluated by light microscopy. Changes following laser irradiation were evaluated by assessing the mitochondrial activity using adenosine triphosphate (ATP) luminescence, cell proliferation using neutral red and an alkaline phosphatase (ALP) activity assay, membrane integrity using lactate dehydrogenase (LDH), and percentage cytotoxicity and DNA damage using the Comet assay. Results: Morphologically, wounded cells exposed to 5 J/ cm 2 migrate rapidly across the wound margin indicating a stimulatory or positive influence of phototherapy. A dose of 5 J/cm 2 has a stimulatory influence on wounded fibroblasts with an increase in cell proliferation and cell viability without adversely increasing the amount of cellular and molecular damage. Higher doses (10 and 16 J/cm 2 ) were characterized by a decrease in cell viability and cell proliferation with a significant amount of damage to the cell membrane and DNA. Conclusions: Results show that 5 J/cm 2 stimulates mitochondrial activity, which leads to normalization of cell function and ultimately stimulates cell proliferation and migration of wounded fibroblasts to accelerate wound closure. Laser irradiation can modify cellular processes in a dose or fluence (J/cm 2 ) dependent manner. Lasers Surg.

Effects of low-level laser therapy on the proliferation and apoptosis of gingival fibroblasts treated with zoledronic acid

“…23,24 Conversely, increased cell proliferation rates have been observed for LLLT-treated cells at both energy doses selected for use in this study (0.5 and 3 J/cm 2 ), confirming that this type of therapy, at specific parameter levels, may biomodulate cell functions. [13][14][15][16][17][18]25,26 Most of the effects of LLLT have been associated with the activation of mitochondrial cytochrome c oxidase, which leads to increased adenosine triphosphate (ATP) production and the activation of several cell-signalling pathways. 27,28 In the present study, it may be speculated that similar laser biostimulation occurred in those irradiated fibroblasts that presented significantly increased proliferation (Table 3).…”

“…[9][10][11][12] Several researchers have demonstrated the biostimulatory effects of LLLT on different cell types, such as increased cell proliferation, migration, differentiation, and protein synthesis, as well as gene expression of collagen type I and growth factors. [13][14][15][16][17] Based on the positive effects of LLLT on bisphosphonate-induced osteonecrosis lesions and the toxic effects of these types of drugs on cells, the aim of the present study was to evaluate the proliferation and apoptosis rates of gingival fibroblasts exposed to ZA treatment and subjected to LLLT according to specific parameters.…”

The use of low-level light therapy in supportive care for patients with breast cancer: review of the literature

“…LLLT can also induce collagen synthesis and growth factor secretion. Furthermore, there is also a downregulation of the production of pro-inflammatory cytokines and cell apoptosis by LLLT [14][15][16][17][18][19][20].…”

Análisis Comparativo del Número de Neurofilamentos en Nervios Isquiáticos de Rata Sometidos a Neuropraxia Tratadas con Láser de Baja Intensidad y Ultrasonido Terapéutico

“…La dosis de irradiación puede cambiar los procesos celulares, además, la aplicación de una dosis baja o muy baja puede producir ningún efecto o incluso efectos negativos o inhibidores (Hawkins & Abrahamse, 2006). En nuestro estudio observamos que la dosis más alta de irradiación por LBI (10 J/ cm 2 ) generó menor reparación nerviosa comparada a la irradiación por dosis más baja (2 J/cm 2 ), lo que confirma lo propuesto por Chen et al (2005) que indican que la irradiación por LBI inadecuada podría impedir o retardar el proceso de regeneración del nervio, por lo tanto, señalamos que es primordial la utilización de un protocolo seguro para irradiación LBI en la práctica clínica.…”