New technologies in dentistry: the regenerative effects of LEDs devices

Aim Low level laser therapy (LLLT), phototherapy or photobiomodulation refers to the use of photons at a non-thermal irradiance to alter biological activity. LLLT uses either coherent light sources (lasers) or non-coherent light sources consisting of filtered lamps or light-emitting diodes (LED) or, on occasion, a combination of both. It Is known that cellular exposure to low energy light activates a set of biochemical pathways, which modulates the activity of many cellular organelles, influencing cellular homeostasis and functionality of several organs. Although Phototherapy is now used to treat a wide variety of ailments, it remains controversial as a therapy for two principle reasons: first, its underlying biochemical mechanisms remain poorly understood, so its use is largely empirical. The aim of the study is to evaluate the effect of light irradiation through a 880 nm LED device on cell degranulation, beta galactosidase activity and interleukin modulation. Methods A NIR-LED device, characterized by an 880 nm-wavelength, has been used as a light source (Tr-Lux, Errevi, Italy). Monocyte/macrophage established tumor cell line U937 cells (ATCC; Manassas, VA, USA) were grown in RPMI 1640 supplemented with 10% heat-inactivated fetal bovine serum (FBS), 2 mM L-glutamine and 1% Pen-Strep at 37 °C in 5% CO2. The concentration of several cytokines was detected using a Cytofluorimetry FITC-labelled assay and the level of expression of p65 NF-kB and cleaved Caspase-3 by Western blot analysis were analyzed. Results This study shows that LED exposure at 880 nm-wavelength activates cell degranulation, beta galactosidase activity and promotes a statistically significant modulation of IL-8 and IL-1β. In all experiments the IL-8 induction was 10 times higher than the basal level. When we tested the LED exposure on U937 cells, in the presence or absence of LPS, surprisingly we observed a slight increase on the release of cytokines in particular regarding IL-8. Additionally, evidences were raised that the well-known pro-inflammatory NF-kB transcription factor and the apoptotic marker, cleaved Caspase-3, were upregulated in response to a proinflammatory biochemical pathway. Conclusions These data, suggest that LED irradiation at these specific parameters is able to promote cellular regeneration on target organs and remodeling process on target cells, including neo-angiogenesis, wound healing and tissue repair mechanisms.