Evaluation of Laser photobiomodulation on bone defect in the femur of osteoporotic rats: a Raman spectral study

摘要

Phototherapies have shown positive effects on the bone repair process, increasing the blood supply to the injured area. The aim of this study was to assess through Raman spectroscopy, the efficacy of laser phototherapy (λ = 780 nm, P = 70 mW, CW, 20.4 J/cm~2 per session, 163.2 J/cm~2 per treatment) on the bone repair process of osteoporotic rats. The osteoporosis induction was achieved by ovariectomy surgery. Thirty Wistar rats were divided into 4 groups (Basal; OVX, OVX + Clot and OVX + Clot + Laser), then subdivided into 2 subgroups according to the experimental time (15 and 30 days). After the osteoporosis induction time (60 days), a bone defect with 2 mm was created with a trephine drill in the right femur in the animals of groups OVX, Clot and Clot + Laser. After surgery, the irradiation protocol was applied in the same groups on repeated sessions every 48 hours during 15 days. The samples were analyzed by Raman Spectroscopy to assess the inorganic content of phosphate and carbonated hydroxyapatite (～960 and 1070 cm~(-1), respectively) and organic lipids and proteins (～1454 cm~(-1)). Statistical analysis (ANOVA, Student-T test) showed significant difference between groups Basal, OVX + Clot, and OVX + Clot + Laser for the inorganic content peaks at ～960 (p≤0.001), and ～1070 cm~(-1) (p≤0.001) in both periods of 15 and 30 days, however on peak at ～1450 cm~(-1) no differences were detected. It was concluded that the Laser phototherapy increased deposition of HA on bone repair process of osteoporotic rats.