IADR Abstract Archives

Low Power Laser Activates Latent TGF-beta1 to Induce Dentin Regeneration

Objectives: There are many anecdotal reports of the efficacy of low power laser treatment in wound healing and regeneration, but the mechanism(s) remain unclear. Here we investigate the hypothesis that laser treatment activates Latent Transforming Growth Factor-β (LTGF-β), and that effect can be exploited to promote dentinogenesis.

Methods: An infrared laser (810nm) was used in all studies, and fluorescent dyes were used to assess generation of reactive oxygen species (ROS). The ability of laser-generated ROS to activate LTGF-β1 was assessed using an ELISA and TGF-β responsive (p3TP-luc) reporter assay. The mechanism of activation of LTGF-β1 by ROS was assessed by change in conformation (circular dichroism) and protein modification (mutational and biochemical analysis). To assay biological impact, mouse pre-odontoblast cell line (MDPC-23) and primary human dental stem cells were cultured on 2D (plastic) and 3D (PLGA) scaffolds, irradiated with lasers and assessed for dentin induction by biomineralization assays (alkaline phosphatase, alizarin red staining), molecular assays (RTPCR and immunoblotting /staining) and elemental analysis (SEM-EDAX and FTIR).

Results: A robust increase in ROS generation was observed with increasing laser dose (0.3 to 30J/cm2 for 5min). Laser treatment was capable of activating LTGFβ-1, and the ROS-mediated activation mechanism involved oxidation of a specific methionine residue (m253), resulting in conformational change; this was confirmed by mutational analysis. Laser irradiation of pre-odontoblasts demonstrated activation of intracellular TGF-β signaling (phospho-Smad2), increase in dentin-specific matrix proteins (Dentin Matrix Protein-1, Osteopontin and Osteomodulin), increased alkaline phosphatase activity, and calcium deposition. Specific inhibitors against ROS or TGF-β in above experiments eliminated these effects, implicating their causal relationship.

Conclusions: This work demonstrates a novel molecular mechanism linking ROS generation by lasers and LTGF-β1 activation that can induce dentinogenesis. Ongoing validation in animal models aims to provide an innovative therapeutic clinical tool for pulp-dentin regeneration.

R1DE019023-02


IADR/AADR/CADR General Session
2011 IADR/AADR/CADR General Session (San Diego, California)
San Diego, California
2011
96
Pulp Biology & Regeneration Research
  • Arany, Praveen R.  ( Harvard University, Cambridge, MA, USA )
  • Hunt, Tristan  ( Harvard University, Cambridge, MA, USA )
  • Hahm, Eason  ( Harvard University, Cambridge, MA, USA )
  • Sidhu, Gursimran  ( Harvard University, Cambridge, MA, USA )
  • Chih-hao Chen, Aaron  ( Harvard University, Boston, MA, USA )
  • Padwa, Bonnie  ( Harvard University, Cambridge, MA, USA )
  • Hamblin, Michael  ( Harvard University, Cambridge, MA, USA )
  • Mooney, David  ( Harvard University, Cambridge, MA, USA )
    • Oral Session
    Tooth Development and Regeneration
    03/16/2011