Photobiostimulation of human neuroblastoma mitochondria with low-level laser therapy (LLLT) using different parameters.

According to WHO (World Health Organization), the prevalence of Alzheimer's disease is higher in developing countries. Also, in the spotlight of veterinarian field, there is a high number of cases of dogs with Canine Cognitive Dysfunction (CCD), a neurodegenerative syndrome, like AD. In both distinct aspects, considering a low-cost therapeutic strategy for neurodegenerative disorders is a matter of urgency. In AD, toxicity of reactive oxygen species stimulates metabolic damage and neurodegeneration, consequently impairing mitochondrial activity and cytoviability. Therefore, treating neurodegenerative diseases, such as AD and CCD, with low-level laser therapy (LLLT) represents an important affordable strategy, providing photophysical, photochemical and photobiological biomodulation on cells. This study evaluates mitochondrial activity of human neuroblastoma (SH-SY5Y) irradiated with LLL, under distinct parameters.Human neuroblastoma (SH-SY5Y) were cultivated and distributed into 5 different LLLT groups, irradiated with the energy density of 1, 5, 10, 15 and 20 J/cm2 laser (Laser specifications: ArGaAl diode laser, Bioset®, (λ)830 nm, (P)200 mW, continuous emission beam Ø3mm), respectively. Cells not exposed to LLLT were used as control and cells exposed to a high concentration of H2 O2 (10mM) were used as positive control for death. 24h and 48h after LLLT, mitochondrial activity was analyzed by MTT, evaluating functional status of the respiratory chain IV through a colorimetric method.As represented in figure 1, there was no statistical difference between any LLLT group compared to the control group 24h after laser irradiation. However, 48h after therapy, all the LLLT groups were statistically significant (p<0.0001), compared to the 48h-control group and compared to 48h-1J/cm2 LLLT group (p<0.5 and p<0.0001). As expected, positive control for death group statistically reduced the cytoviability (p <0.0001) compared to the respective control group.LLLT positively photobiostimulates and modulate mitochondrial activity of human neuroblastoma, specially using 1J/cm2 48h after therapy. Our further steps include the elucidation of metabolic modulation of laser irradiation on human neuroblastoma and glial cells under induced stress and the investigation of LLLT on CCD. References: (1) WHO(2017).Global ActionPlan on the Public Health Response to Dementia_2017-2025. (2) Xuan,Weijun,et al."Transcranial low-level laser therapy improves neurological performance in traumatic brain injury in mice: effect of treatment repetition regimen."PloS one8.1(2013):e53454.