Comparative analysis of different doses of coherent light (laser) and non-coherent light (light-emitting diode) on cellular necrosis and apoptosis: a study in vitro

Abstract

Introduction: Threshold doses of electromagnetic radiation can initiate necrosis and apoptosis in cells. The purpose of this study was to evaluate cellular apoptosis and necrosis immediately (t 0 ) and 24 hours (t 24 ) after irradiation with different doses of coherent light (laser) or non-coherent light (LED). Methods: CHO-K1 lineage cells were irradiated with laser (810nm) or LED (945±20nm), with 24mW, contact area of 1cm 2 and doses of 10, 20, 30, 40 and 50J/cm 2 for 300, 660, 960, 1230 and 1620s, respectively, at both wavelengths. Cells were evaluated by fluorescence microscopy, differentiating viable, apoptotic and necrotic cells immediately and 24 hours after irradiation. Results: The number of necrotic cells at t 0 was higher in the LED 40 and 50J/cm 2 groups (86±14 and 84±16% respectively, p <0.05), than in the 10 and 20J/cm 2 laser (5±2 and 5±3%, p<0.05) and LED (5±3 and 4±1%, p<0.05) conditions. At t 24, the LED 40J/cm 2 (80±20%, p<0.05) group also showed more necrosis than the control and lower dose groups (laser 10, 20, and 30J/cm 2 percentage of 6±4, 10±3 and 7±3%, p<0.05; LED 10 and 20J/cm 2 percentage of 3±1 and 17±10%, p<0.05). A decrease in apoptotic cells was observed in the laser group with doses of 10, 40, and 50J/cm 2 (6±4, 3±1 and 1±1% respectively, not significant), as well as in the LED 40J/cm 2 (2±2%, not significant) group versus control. The cells had a higher percentage of apoptosis cells in the control group and with laser doses of 10 and 30J/cm 2 (percentage of 20±1 and 20±4%, not significant), while only the LED 40J/cm 2 (10±10%, not significant) had a lower percentage compared the control group. Conclusion: Laser or LED stimulation promoted an increase in cell necrosis in a high energy density condition as characterized in a dose-dependent inhibition therapy. Laser or LED infrared irradiation in low doses (up to 20J/cm 2 ) reduced the percentage of apoptosis in CHO-K1 cells, while high doses (30J/cm 2 ) elevated apoptosis.

Analysis of laser therapy effects in Sporothrix schenckii inactivation in vivo

“…Several studies have reported the possibility of using a low-power laser in many areas of medicine, such as in vitro experiments to reduce the rate of apoptosis (Silva et al, 2016), experimental models to reduce tetanic contractions (Giaretta et al, 2016), improvement in muscle function (Giaretta et al, 2015), treatment of acute medullary trauma (Abreu et al, 2011) pulmonary inflammation (Oliveira et al, 2010), bone defects (Feitosa et al, 2012), tendinopathies (Bjordal et al, 2003), neuro-rehabilitation (Hashmi et al, 2010), chronic obstructive pulmonary disease (Alves et al, 2010), and as an alternative treatment therapy of various diseases caused by microorganisms (Dai et al, 2009;Donnelly et al, 2008;Gilaberte et al, 2014;Hees et al, 2012; Javed et al, 2014; Kozarev, 2010; Soukos and Goodson, 2011).…”