Résumé
Abstract The aim of this experimental study was to determine the effect of photobiomodulation therapy on bone repair in a rat tibia osteotomy model at 15 and 30 days. The sample consisted of 36 male Holtzman rats that were randomized into 6 equal groups. Groups A1 and A2: osteotomy + 1 J laser energy. Groups B1 and B2: osteotomy + 3 J laser energy. Groups C1 and C2 (controls): osteotomy only. The bone repair was analyzed by histological evaluation of osteoblasts and osteocytes both at 15 days (groups A1, B1, and C1) and at 30 days (groups A2, B2, and C2). Within the results, in all groups a greater number of osteoblasts was found at 15 days vs 30 days (p<0.05), and a greater number of osteocytes in B1 and C2 vs B2 and C1, respectively (p<0.05). When evaluating the 3 groups worked up to 15 days, more osteoblasts were found in A1 and C1 vs B1 (p<0.001); and osteocytes predominated in A1 and B1 vs C1 (p<0.001). At 30 days there was a greater quantity of osteoblasts in C2 vs A2 and B2 (p<0.05) and of osteocytes in C2 vs B2 (p<0.05). It is concluded that 1 J photobiomodulation therapy improved bone repair at 15 days; however, this improvement was not observed at 30 days because there were no differences between the irradiated groups and the control.
Resumen El objetivo de este estudio experimental fue determinar el efecto de terapia de fotobiomodulación sobre la reparación ósea en un modelo de osteotomía de tibia de rata a los 15 y 30 días. La muestra estuvo compuesta por 36 ratas Holtzman macho que se aleatorizaron en 6 grupos iguales. Grupos A1 y A2: osteotomía + energía láser de 1 Joule. Grupos B1 y B2: osteotomía + energía láser 3 Joule. Grupos C1 y C2 (controles): solo osteotomía. La reparación ósea fue analizada por evaluación histológica de osteoblastos y osteocitos tanto a los 15 días (grupos A1, B1 y C1) como a los 30 días (grupos A2, B2 y C2). Como resultados se encontró que en todos los grupos hubo mayor número de osteoblastos a los 15 días vs. 30 días (p<0,05), y mayor número de osteocitos en B1 y C2 vs B2 y C1, respectivamente (p<0,05). Al evaluar a los animales a los 15 días, se observó mayor número de osteoblastos en A1 y C1 vs B1 (p<0.001); y mayor número de osteocitos en A1 y B1 vs C1 (p<0,001). Al evaluar a los ratones a los 30 días hubo mayor cantidad de osteoblastos en C2 vs A2 y B2 (p<0,05) y de osteocitos en C2 vs B2 (p<0,05). Se concluye que la terapia de fotobiomodulación con 1 Joule mejoró la reparación ósea a los 15 días; sin embargo, dicha mejora no se observó a los 30 días porque no hubo diferencias entre los grupos irradiados y el control.
Sujets)
Animaux , Rats , Tibia , Photobiologie , Photothérapie de faible intensité , Os et tissu osseuxRésumé
BACKGROUND: The human dermal papilla cells (hDPCs) play an important role in regulation of hair cycling and growth. OBJECTIVE: The aim of this study was to investigate the effect of different wavelengths of light-emitting diode (LED) irradiation on the proliferation of cultured hDPCs and on the growth of human hair follicles (HFs) in vitro. METHODS: We examined the effect of LED irradiation on Wnt/β-catenin signaling and mitogen-activated protein kinase (MAPK) pathways in hDPCs. Anagen HFs were cultured with LED irradiation and elongation of each hair shaft was measured. RESULTS: The most potent wavelength in promoting the hDPC proliferation is 660 nm and 830 nm promoted hDPC proliferation to a lesser extent than 660 nm. Various wavelengths significantly increased β-catenin, Axin2, Wnt3a, Wnt5a and Wnt10b mRNA expression. LED irradiation significantly increased β-catenin and cyclin D expression, and the phosphorylation of MAPK and extracellular signal-regulated kinase (ERK). HFs irradiated with 415 nm and 660 nm grew longer than control. CONCLUSION: Our result suggests that LED has a potential to stimulate hDPC proliferation via the activation of Wnt/β-catenin signaling and ERK pathway. To our best knowledge, this is the first report which investigated that the effect of various wavelengths of LED on hDPC proliferation and the underlying mechanisms.
Sujets)
Humains , Cycline D , Extracellular Signal-Regulated MAP Kinases , Follicule pileux , Poils , Techniques in vitro , Système de signalisation des MAP kinases , Phosphorylation , Phosphotransferases , Protein kinases , ARN messagerRésumé
Low-level laser or light therapy (LLLT) was used to accelerate wound healing without the use of thermal effects in the early days. Although the exact mechanism of LLLT is still unclear, it has been recognized as a photobiomodulation process. Today, LLLT is being credited as a non-invasive treatment modality, and in particular, being widely applied in the field of dermatology. In this review, we summarize the basic principles and clinical applications of LLLT to provide an up-to-date guidance on its practical and safe uses. Further studies are needed to elucidate the mechanism of action of LLLT in various indications, and to determine the wavelength and dose for optimal clinical use.