In Vitro Effects of Photobiomodulation with 660 Nm Laser and Vitamin D on Osteoblastic Differentiation of Human Periodontal Ligament Stem Cells.

Background: Mesenchymal stem cells (MSCs) can be found inside the human periodontal ligament. Application of vitamin D and photobiomodulation for regulation of the proliferation of MSCs and bone differentiation have been recently considered in cell engineering. This study is performed to evaluate the effects of photobiomodulation with 660 nm laser exposure and vitamin D on human periodontal ligament stem cells (HPDLSCs) and their osteoblastic differentiation properties.

Materials and methods: This study, was an in vitro experimental study performed on HPDLSCs in six groups of (I) control cells in the culture medium with no intervention, (II) addition of 10-7 mol vitamin D to the medium, (III) 660 nm diode laser exposure in 3 J/cm2 density of energy, (IV) 660 nm diode laser exposure in 3 J/cm2 density of energy + addition of 10-7 mol vitamin D to the medium, (V) 660 nm diode laser exposure in 5 J/cm2 density of energy, and (VI) 660 nm diode laser exposure in 5 J/cm2 density of energy + addition of 10-7 mol vitamin D to the medium. after 24 hours of the last exposure, cell viability had been assessed by methyl thiazolyl tetrazolium assay. The expression of Runt-related transcription factor 2 (RUNX2), osteopontin (OPN), alkaline phosphatase (ALP), and osteocalcin (OCN) genes was also assessed by reverse transcription-polymerase chain reaction, then Alizarin red staining was used to assess calcification.

Results: Combined use of 660 nm laser with 3 and 5 J/cm2 density of energy and 10-7 mol vitamin D significantly increased cell viability, osteoblastic differentiation by upregulation of RUNX2, ALP, OPN, and OCN, and calcification (P0.05).

Conclusion: The results showed that combined use of vitamin D3 and irradiation of 660 nm laser with 3 J/cm2 and particularly 5 J/cm2 energy density increased the viability of HPDLSCs and enhanced their osteoblastic differentiation.