Differential Response of Stro-1+ and Stro-1- Shed to Er,Cr:YSGG Laser Stimulation: Viability, Matrix Production and Lineage Commitment.

Stem cell heterogeneity represents a critical yet underexplored variable in laser-assisted regenerative strategies. While photobiomodulation has been shown to influence mesenchymal stem cell (MSC) behavior, it remains unclear whether stem cell maturation status modulates responsiveness to Er,Cr:YSGG irradiation. This study investigated the differential response of magnetically separated STRO-1+ and STRO-1- SHED subpopulations to low-power Er,Cr:YSGG laser stimulation (0.10 W and 0.25 W), focusing on viability, extracellular matrix production, and lineage commitment. STRO-1+ cells comprised 13.4% ± 1.2% of the total Stem Cells from Human Exfoliated Deciduous teeth (SHED) population. Laser exposure did not impair metabolic activity in either subpopulation. Collagen synthesis demonstrated a power- and time-dependent increase, with maximal enhancement observed in STRO-1+ cells at 0.25 W after 7 days. Laser irradiation selectively promoted osteogenic differentiation, as evidenced by increased alkaline phosphatase (ALP) expression at 0.10 W and enhanced mineral deposition, while chondrogenic potential remained unaffected and adipogenesis was reduced following 0.10 W exposure. These findings suggest that ALP expression is temporally and power-dependently modulated during osteogenic progression. Overall, Er,Cr:YSGG photobiomodulation does not uniformly affect heterogeneous SHED populations but modulates lineage allocation and extracellular matrix deposition in a maturation- and power-dependent manner. Integrating stem cell subpopulation selection with laser-based bioactivation may represent a strategy to refine regenerative endodontic and biomaterial-guided therapies.