Influência de diferentes protocolos de déficit nutricional e densidade de energia na biomodulação de células-tronco de dentes decíduos esfoliados humanos (SHED)

Abstract

The purpose of the present study was to analyze in vitro the effects of different nutritional deficit conditions to induce the state of cellular stress, prior to irradiation with different dosimetries of Low Level Laser Therapy (LLLT), on the biomodulation of stem cells from human exfoliated deciduous teeth (SHED). These cells, cultured in MEMα culture medium supplemented with 10% FBS, between the 10th and 15th passage, were subjected to nutritional deficit with 1% FBS one hour or 24 hours prior to irradiation (protocols A or B, respectively). In both protocols, cells were irradiated with red laser (660 nm) in the following dosimetries: 2.5 J/cm2 (groups I and V), 5.0 J/cm2 (groups II and VI) and 7.5 J/cm2 (groups III and VII). Non-irradiated cells constituted the negative (group IV) and positive (group VIII) controls. Evaluation of citotoxicity/integrity of cellular membrane was performed by the quantification of lactate dehydrogenase (LDH) in the culture medium after irradiation. Cell viability was assessed by MTT method 24, 48 and 72 hours after irradiation. Data were submitted to two-way ANOVA followed by Tukey test (P<0.05). The levels of LDH at the culture medium where SHED were grown were similar when compared protocols A and B for the same energy density and same concentration of FBS during irradiation. In protocol A, cells were more viable 24 hours after irradiation, irrespective of the energy density, while in protocol B, there was no alteration in cell viability in groups IV (negative control), V, VI, VII and VIII (positive control) over time. Therefore, the induction of cellular stress by culture medium supplementation with 1% FBS, one hour prior to irradiation, was more favorable for maintaining SHED viability after irradiation, with no alteration in the levels of extracellular LDH, in comparison with the results after 24-hour nutritional deficit.