Biological effects of low-level laser irradiation (LLLI) on stem cells from human exfoliated deciduous teeth (SHED).

ABSTRACT

OBJECTIVES: To investigate the effects of low-level laser irradiation (LLLI) on viability/proliferation, migration, osteo/odontogenic differentiation, and in vitro biomineralization of stem cells from human exfoliated deciduous teeth (SHED). MATERIALS AND METHODS: SHED cultures were established by enzymatic dissociation from pulps of deciduous teeth. SHED were irradiated with a diode laser (InGaAsP; 940 nm; 0.2 W, continuous mode) at energy fluences 4, 8, and 16 J/cm2 in the dark, while non-irradiated SHED served as control. Cell viability/proliferation was evaluated by MTT assay and cell mobilization by Transwell™ migration assay. Expression of osteo/odontogenesis-related genes (ALP, BMP-2, BGLAP, DSPP, MSX2, RUNX2) was assessed by real-time PCR, while in vitro biomineralization by Alizarin Red staining. Statistical analysis was performed by two-way ANOVA and Tukey's post hoc tests (*p < 0.05, **p < 0.01). RESULTS: Statistically significant stimulation of cell viability/proliferation was observed at all energy fluences, reaching the highest effect for the 4 and 16 J/cm2. Although the 8 J/cm2 fluence showed the lowest stimulatory effect on cell viability/proliferation, it was the most effective in inducing SHED migration, upregulation of odontogenesis-related genes (DSPP, ALP, BMP-2) at specific time-points, and the in vitro biomineralization potential of SHED compared to the other two energy fluences. CONCLUSIONS: LLLI proved beneficial in promoting SHED biological processes critical for pulp repair in deciduous teeth. Overall, the 8 J/cm2 energy fluence showed the most beneficiary effects. CLINICAL RELEVANCE These results provide insights on a narrow "therapeutic window" of LLLI application in vital pulp therapies of deciduous teeth, paving the way for the establishment of effective clinical protocols.