Effects of phototherapy on cartilage structure and inflammatory markers in an experimental model of osteoarthritis

Abstract

The aim of this study was to evaluate the effects of laser phototherapy on the degenerative modifications on the articular cartilage after the anterior cruciate ligament transection (ACLT) in the knee of rats. Eighty male rats (Wistar) were distributed into four groups: intact control group (IG), injured control group (CG), injured laser treated group at 10 J/cm(2) (L10), and injured laser treated group at 50 J/cm(2) (L50). Animals were distributed into two subgroups, sacrificed in 5 and 8 weeks postsurgery. The ACLT was used to induce knee osteoarthritis in rats. After 2 weeks postsurgery, laser phototherapy initiated and it was performed for 15 and 30 sessions. The histological findings revealed that laser irradiation, especially at 10 J/cm(2), modulated the progression of the degenerative process, showing a better cartilage structure and lower number of condrocytes compared to the other groups. Laser phototherapy was not able to decrease the degenerative process measured by Mankin score and prevent the increase of cartilage thickness related to the degenerative process. Moreover, it did not have any effect in the biomodulation of the expression of markers IL1β, tumor necrosis factor-α, and metalloprotein-13. Furthermore, laser irradiated animals, at 50 J/cm(2) showed a lower amount of collagen type 1.

Effects of low-level laser therapy on the expression of osteogenic genes during the initial stages of bone healing in rats: a microarray analysis

“…From digitalized images of the defect, the amount of newly formed bone was determined within five regions of interest, i.e.,: ROI1 (upper region of the border), ROI2 (right border), ROI3 (bottom region of the border), ROI4 (left border), and ROI5 (central region of the bone defect). This analysis was established in a previous study conducted by our team [6,7]. The amount of newly formed bone was determined in square micrometers in each ROI, and the total newly formed bone was represented as ROI1+ ROI2+ ROI3+ ROI4+ ROI5.…”

“…The animals received analgesia (i.m., 0.05 mg/kg buprenorphine (Temgesic; Reckitt Benckiser Health Care Limited, Schering Plough, Hoddesdon, UK) and were returned to their cages. The health status of the rats was monitored daily [6,7].…”

“…In this context, the clinical demand for therapeutic strategies to promote bone repair has been growing in recent years in direct relation to the increase on the human population [4]. One of the most promising treatments is the use of low-level laser therapy (LLLT), which is able of reestablishing cellular homeostasis and regenerating biological tissues, such as the muscle, tendons, cartilage, and bone [1,[5][6][7][8][9].…”

“…Moreover, it has been demonstrated that LLLT can stimulate VEGF expression and angiogenesis [6,17]. Thus, this therapeutic modality has been used to promote wound healing, to accelerate tissue repair, and to modulate the inflammatory process after injuries [7,18].…”

“…Furthermore, LLLT modulates the expression of some inflammatory mediators such as Cyclooxygenase-2 (COX-2), tumor necrosis factor α (TNFα), interleukin 1β, (IL1β), and interleukin 10 (IL10) [7,15,16]. Moreover, it has been demonstrated that LLLT can stimulate VEGF expression and angiogenesis [6,17].…”