LLLT Affects Attachment, Proliferation And TGF-ß1 Production in Osteoblast-like Cells

Objective: In animal studies, the biostimulating effect of low laser therapy (LLLT) has been demonstrated successfully in more rapid healing bone defects at a dose of 2.4 J. However, the effect of LLLT directly on osteoblasts grown on titanium implant materials has not been clarified yet. This in vitro study was aimed to examine the effect of LLLT with a GaAlAs diode laser device on attachment, proliferation and production of transforming growth factor-ß1 (TGF-ß1) in human osteoblast-like cells (HOB). Methods: Cells derived from human mandibular bone were exposed to GaAlAs diode laser at dosages of 1.5 or 3 J/cm2 and then seeded on titanium discs. Non-lased cultures were used as control groups. After 1, 3 and 24 h cells were stained by Hoechst and Prodidium iodide staining and the attached cells were counted under a Zeiss confocal microscope. The cells were also cultured on the titanium specimens for 24 h and then treated by the laser for three consecutive days to investigate cell proliferation after 48, 72 and 96 h. Furthermore, cellular production of TGF-ß1 after 10 days was measured by an enzyme-linked immunosorbent assay (ELISA), using commercially available Kits. Results: The cellular attachment was significantly enhanced with LLLT (P<0.05). The proliferation assays after 96 h but not after 48 and 72 h, showed higher cell proliferation on the irradiated groups than on non-irradiated cells. The greatest production of TGF-ß1 was on cells exposed to 3 J/cm2. Conclusion: These results showed that osteoblast-like cells cultured on titanium implant material, had a tendency for increased cellular attachment, proliferation and production of TGF-ß1 in response to low level laser, indicating that LLLT may modulate the activity of cells and tissues surrounding an implant.