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This study assessed the impact of low-level laser irradiation on the viability and proliferation of human periodontal ligament stem cells (hPDLSCs) cultivated on polylactic acid (PLA) scaffolds. hPDLSCs were obtained, characterized, and grown on the surface of PLA films produced via the solvent casting technique. The study involved two groups: the control group, which was not exposed to radiation, and the laser group, which was irradiated with a diode laser (InGaAIP) with a power of 30 mW, a wavelength of 660 nm, and a single dose of 1 J/cm² emitted continuously. Cell viability was assessed 24 and 48 hours after irradiation using the Alamar blue and Live/Dead assays. Flow cytometry was used to assess cell cycle events, and scanning electron microscopy (SEM) was used to evaluate the interaction between cells and the biomaterial. The results revealed a statistically significant increase in cell metabolic activity in the laser group compared with the control group at 24 hours (p <0.05) and 48 hours (p <0.001), as indicated by the Alamar blue assay. The Live/Dead assay also revealed a greater density of viable cells in the laser group. The cell cycle analysis revealed a significant increase in the number of cells in the proliferative phase (G2/M) in the laser group compared with the control group (p <0.001). The SEM images demonstrated that the irradiated group had a greater concentration of cells while still maintaining their cell shape and projections. This study demonstrated that photobiomodulation can increase the viability and proliferation of periodontal stem cells cultured on PLA scaffolds, suggesting the potential of this protocol for future studies on periodontal tissue engineering., (© 2024. The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.)

Low-level laser irradiation (LLLI) stimulates the proliferation of a variety of cell types. However, very little is known about the effect of laser therapy on dental stem cells. The aim of the present study was to evaluate the effect of LLLI (660 nm, 30 mW) on the proliferation rate of human periodontal ligament stem cells (hPDLSC), obtained from two healthy permanent third molars extracted due to surgical indication. Culture cells were either irradiated or not (control) with an InGaAIP diode laser at 0 and 48 h, using two different energy densities (0.5 J/cm², 16 s and 1.0 J/cm², 33 s). Cell proliferation was evaluated by the Trypan blue exclusion method and by measuring mitochondrial activity using the MTT-based cytotoxicity assay at intervals of 0, 24, 48, and 72 h after the first laser application. An energy density of 1.0 J/cm² improved the cell proliferation in comparison to the other groups (control and laser 0.5 J/cm²) at 48 and 72 h. The group irradiated with 1.0 J/cm² presented significantly higher MTT activity at 48 and 72 h when compared to the energy density of 0.5 J/cm². It can be concluded that LLLI using infrared light and an energy density of 1.0 J/cm² has a positive stimulatory effect on the proliferation of hPDLSC.

Cryopreservation aims to cease all biological functions of living tissues in a reversible and controlled manner, i.e., to permit the recovery of cells by maintaining a high degree of their viability and functional integrity. The objective of this study was to evaluate in vitro the influence of cryopreservation on undifferentiated mesenchymal cells derived from the periodontal ligament of human third molars. Mesenchymal cells were isolated from six healthy teeth and cultured in α-MEM medium supplemented with antibiotics and 15% FBS in a humid atmosphere with 5% CO(2) at 37°C. The cells isolated from each tooth were divided into two groups: group I (fresh, non-cryopreserved cells) was immediately cultured, and group II was submitted to cryopreservation for 30 days. The rates of cell adhesion and proliferation were analyzed in the two groups by counting the cells adhered to the wells at 24, 48 and 72 h after plating. The number of cells per well was obtained by counting viable cells in a hemocytometer using the Trypan blue exclusion method. Differences between groups at each time point were evaluated by the Wilcoxon test. The Friedman test was used to determine differences between time points and, if detected, the Wilcoxon test with Bonferroni correction was applied. The results showed no significant difference in the in vitro growth capacity of undifferentiated mesenchymal cells between the two groups. In conclusion, cryopreservation for 30 days had no influence on periodontal ligament mesenchymal cells.

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Piceatannol is a resveratrol metabolite that is considered a potent antioxidant and cytoprotector because of its high capacity to chelate/sequester reactive oxygen species. In pathogenesis of periodontal diseases, the imbalance of reactive oxygen species is closely related to the disorder in the cells and may cause changes in cellular metabolism and mitochondrial activity, which is implicated in oxidative stress status or even in cell death. In this way, this study aimed to evaluate piceatannol as cytoprotector in culture of human periodontal ligament fibroblasts through in vitro analyses of cell viability and oxidative stress parameters after oxidative stress induced as an injury simulator. Fibroblasts were seeded and divided into the following study groups: control, vehicle, control piceatannol, H2O2 exposure, and H2O2 exposure combined with the maintenance in piceatannol ranging from 0.1 to 20 μM. The parameters analyzed following exposure were cell viability by trypan blue exclusion test, general metabolism status by the 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) method, mitochondrial activity through the ATP production, total antioxidant capacity, and reduced gluthatione. Piceatannol was shown to be cytoprotective due the maintenance of cell viability between 1 and 10 μM even in the presence of H2O2. In a concentration of 0.1 μM piceatannol decreased significantly cell viability but increased cellular metabolism and antioxidant capacity of the fibroblasts. On the other hand, the fibroblasts treated with piceatannol at 1 μM presented low metabolism and antioxidant capacity. However, piceatannol did not protect cells from mitochondrial damage as measured by ATP production. In summary, piceatannol is a potent antioxidant in low concentrations with cytoprotective capacity, but it does not prevent all damage caused by hydrogen peroxide. [ABSTRACT FROM AUTHOR]