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In vivo evidence of blue-LED-light photobiomodulation
1 , 1 , * 2 , 1, 3 , 1 , 4, 5 , 5, 6 , 1
1  Istituto di Fisica Applicata “Nello Carrara”, Consiglio Nazionale delle Ricerche (IFAC-CNR), 50019 Sesto Fiorentino, Florence, Italy
2  Institute of Applied Physics "Nello Carrara", National Research Council
3  Dipartimento di Biologia, Università di Firenze, 50019 Sesto Fiorentino, Florence, Italy
4  Istituto Nazionale di Ottica, Consiglio Nazionale delle Ricerche (INO-CNR), 50125 Sesto Fiorentino, Florence, Italy
5  Laboratorio Europeo di Spettroscopia Non-Lineare (LENS), Università di Firenze, 50019 Sesto Fiorentino, Florence, Italy
6  Dipartimento di Fisica, Università di Firenze, 50019 Sesto Fiorentino, Florence, Italy
Academic Editor: Allan Stensballe


Blue LED light (410-430 nm) induces hemostasis through a photo-thermo-coagulation process, mediated by the absorption of the light from macromolecules naturally present in tissues, such as hemoglobin or even the cytochrome C. These macromolecules can trigger intracellular pathways, which are involved in the healing process. Clinical evidence of PhotoBioModulation (PBM) has been observed, and blue-light treatment is successfully used in dermatological practice and in wound management. Here, we describe the effects of the one-time application of 20.6 J/cm2 of blue LED light in two murine models: superficial and full-thickness wounds. In the first model (33 CD1 mice), the inflammatory response was studied: neutrophils, mast cells and their degranulation index, M1 and M2 macrophages, and endothelial cells were investigated after 1-3-6-9-12-18-24-72-144 hours from the wound induction by histology and immunofluorescence analysis. In the second model, 63 CD1 mice were randomized into three groups: in two groups one wound was performed, while two wounds were induced in the other group. Only one wound was treated by applying 20.6 J/cm2 of blue light. The animals were sacrificed after 1-3-6-9- 24 hours and 7-14 days after the treatment. An ELISA assay was used to study EGF, bFGF, VEGF, TNF-α, MMP-2 and pro-MMP-9. Our findings show that the treated samples have a higher immunity reaction in the time span between 1 and 9 hours, but a lower degree of inflammation after 24 hours. After 24 hours, an increase in mast-cell density and their degranulation index correlated to the expression of the MHC was found. The expression of bFGF, EGF and Pro-MMP-9 evidenced a modulation due to the light treatment. These results demonstrated that blue-LED-light PBM stimulates an earlier activation of the first phases of wound healing, leading to a faster recovery of the wounded tissue. On these bases, blue LED light can be considered a valid additional treatment to standard therapies in wound management.

Keywords: Blue light; wound healing; Photobiomodulation; inflammatory response;