Low Level Laser Therapy With an 810-nm Diode Laser Affects the Proliferation and Differentiation of Premature Osteoblasts and Human Gingival Fibroblasts In Vitro

Effect of Low-Level Laser Irradiation (810 nm) on the Proliferation and Differentiation of Osteoblast-Like Cells Cultured on SLA Titanium Discs Exposed to a Peri-implantitis Environment

Introduction: Elimination of inflammation and re-osseointegration are the major objectives of peri-implantitis therapy. Existing data, however, do not support any decontamination approach. Thus, the present in vitro study aims to assess whether the air-debriding decontamination method with erythritol powder restores the biocompatibility of infected titanium discs and to investigate the potent biomodulatory ability of diode laser (810 nm) irradiation to promote cell proliferation and differentiation of premature osteoblast-like cells (MG63) towards osteocytes. Methods: The experimental groups consisted of cells seeded on titanium discs exposed or not in a peri-implantitis environment with or without biomodulation. Infected discs were cleaned with airflow with erythritol powder. Cell cultures seeded on tricalcium phosphate (TCP) surfaces with or without biomodulation with a laser (810 nm) were used as controls. The study evaluated cell viability, proliferation, adhesion (SEM) at 24, 48 and 72 hours, and surface roughness changes (profilometry), as well as the effects of low-level laser therapy (LLLT) on ALP, OSC, TGF-b1, Runx2, and BMP-7 expression in MG63 cells' genetic profile on days 7, 14, and 21. Results: The MTT assay as well as the FDA/PI method revealed that cell proliferation did not show significant differences between sterile and decontaminated discs at any timepoint. SEM photographs on day 7 showed that osteoblast-like cells adhered to both sterile and disinfected surfaces, while surface roughness did not change based on amplitude parameters. The combination of airflow and LLLT revealed a biomodulated effect on the differentiation of osteoblast-like cells with regard to the impact of laser irradiation on the genetic profile of the MG63 cells. Conclusion: In all groups tested, osteoblast-like cells were able to colonize, proliferate, and differentiate, suggesting a restoration of biocompatibility of infected discs using airflow. Furthermore, photomodulation may promote the differentiation of osteoblast-like cells cultured on both sterile and disinfected titanium surfaces.

Synergistic effects of integrin binding peptide (RGD) and photobiomodulation therapies on bone-like microtissues to enhance osteogenic differentiation

Bone tissue engineering aims to diversify and enhance the strategies for bone regeneration to overcome bone-related health problems. Bone mimetic peptides such as Gly-Arg-Gly-Asp-Ser (RGD) are useful tools for osteogenic differentiation. Similarly, photobiomodulation (PBM) at 600-800 nm of wavelength range improves bone tissue healing via the production of intracellular reactive oxygen species (ROS), ATP synthesis, and nitric oxide (NO) release. Besides, traditional monolayer cell culture models have limited conditions to exhibit the details of a mechanism such as a peptide or PBM therapy. However, scaffold-free microtissues (SFMs) can mimic a tissue more properly and be an efficient way to understand the mechanism of therapy via cell-cell interaction. Thus, the synergistic effects of RGD peptide (1 mM) and PBM applications (1 J/cm² energy density at 655 nm of wavelength and 5 J/cm² energy density at 808 nm of wavelength) were evaluated on SFMs formed with the co-culture of Human Bone Marrow Stem Cells (hBMSC) and Human Umbilical Vein Endothelial Cells (HUVEC) for osteogenic differentiation. Cell viability assays, mechanistic analysis, and the evaluation of osteogenic differentiation markers were performed. Combined therapies of RGD and PBM were more successful to induce osteogenic differentiation than single therapies. Especially, RGD + PBM at 655 nm group exhibited a higher capability of osteogenic differentiation via ROS production, ATP synthesis, and NO release. It can be concluded that the concomitant use of RGD and PBM may enhance bone regeneration and become a promising therapeutic tool to heal bone-related problems in clinics.