Efeitos da irradiação com laser de baixa intensidade vermelha e infravermelha na viabilidade e proliferação de células-tronco derivadas da polpa de dentes decíduos humanos (SHED)

Abstract

The aim of this study was to evaluate the in vitro effects of different energy density of visible and infrared Low-level laser (LLL) on the viability and proliferation of stem cells from human exfoliated deciduous teeth (SHED). SHED were maintained in MEMα culture medium supplemented with 10% fetal bovine serum (FBS) and 1% penicillin and streptomycin. Between the 10th and 15th passages, SHED were irradiated with red laser (I - 660 nm) or infrared laser (II - 780 nm) set with the following dosimetry: a (1.2 J/cm 2 ), b (2.5 J/cm 2 ), c (5.0 J/cm 2 ), d (7.5 J/cm 2 ), C+ (non-irradiated cells, grown under regular nutritional conditions - 10% FBS), C- (non-irradiated cells, grown under nutritional deficit - 1% FBS). Cell viability was assessed by MTT and Crystal Violet (CV) assays, and proliferation through SRB after 24, 48 and 48 h of irradiation. The values were analyzed by two-way ANOVA followed by Tukey test with statistical significance established at 5%. At 24 and 48 h period, group Ic showed significantly higher rates cell viability rates than Ia by MTT, and Ib group through CV assay. At 48 h, Ib also revealed lower proliferation than Ic. Comparing to the C+ group, Ib exhibited lower viability at 72 h, and proliferation at 24 and 48 h. Ia, IIa and IIc groups were less viable at 24 h, while Ia, IIb e IIc revealed lower proliferative capacity at 48 h. Regarding to the different types of laser, Ic enhanced SHED viability in comparison to IIc at 24 and 48 h. Ia e Ib groups showed lower cell viability rates than IIa e IIb at 48 h. In this period, cell proliferation rate of Ib was also lower than IIb. According to the results, 5 J/cm2 applied by red LLL induced high rates of cell viability and proliferation, while the irradiation of this dose for infrared laser led to negative effects. LLL irradiation with 1.2 and 2.5 J/cm2 caused damage to metabolic activity and proliferation of SHED regardless of the type of laser, and the reduction of viability and cell proliferation rates was higher after the application of these doses with red laser.