Biostimulatory effect of low-level laser therapy on keratinocytes in vitro

Epithelial cells play an important role in reparative events. Therefore, therapies that can stimulate the proliferation and metabolism of these cells could accelerate the healing process. To evaluate the effects of low-level laser therapy (LLLT), human keratinocytes were irradiated with an InGaAsP diode laser prototype (LASERTable; 780?±?3 nm; 40 mW) using 0.5, 1.5, 3, 5, and 7 J/cm² energy doses. Irradiations were done every 24 h totaling three applications. Evaluation of cell metabolism (MTT assay) showed that LLLT with all energy doses promoted an increase of cell metabolism, being more effective for 0.5, 1.5, and 3 J/cm². The highest cell counts (Trypan blue assay) were observed with 0.5, 3, and 5 J/cm². No statistically significant difference for total protein (TP) production was observed and cell morphology analysis by scanning electron microscopy revealed that LLLT did not promote morphological alterations on the keratinocytes. Real-time polymerase chain reaction (qPCR) revealed that LLLT also promoted an increase of type I collagen (Col-I) and vascular endothelial growth factor (VEGF) gene expression, especially for 1.5 J/cm², but no change on fibroblast growth factor-2 (FGF-2) expression was observed. LLLT at energy doses ranging from 0.5 to 3 J/cm² promoted the most significant biostimulatory effects on cultured keratinocytes.     

Effect of low-level laser therapy on types I and III collagen and inflammatory cells in rats with induced third-degree burns

Low-level laser therapy (LLLT) has been increasingly used to accelerate wound healing in third-degree burns. This study investigated the effects of lasers on the tissue repair process of third-degree burns. Burns were produced on the backs of male Wistar rats. The animals were divided into four groups (n?=?12): control, injury, LLLT 3 J/cm², and LLLT 4 J/cm². Each group was further divided into two subgroups; the rats in one subgroup were killed on day 8 and those in the other, on day 16 after injury. The animals in LLLT 3 J/cm² and LLLT 4 J/cm² were irradiated 1 h after injury, and irradiation was repeated every 48 h. Laser (660 nm, 35 mW) treatment at fluences of 3 and 4 J/cm² were used. After killing the rats, tissue fragments from the burnt area were removed for histological analysis. The LLLT-treated groups showed a significant decrease (p <0.05) in the number of inflammatory cells and increased collagen deposition compared to the injury group. Laser irradiation (both 3 and 4 J/cm²) resulted in reduction in the inflammatory process and improved collagen deposition, thereby ameliorating the healing of third-degree burns.     

Effect of low-level laser therapy on healing of tenotomized Achilles tendon in streptozotocin-induced diabetic rats

Diabetes mellitus (DM) is associated with musculoskeletal damage. Investigations have indicated that healing of the surgically tenotomized Achilles tendon was considerably augmented following low-level laser therapy (LLLT) in non-diabetic, healthy animals. The aim of the present study was to evaluate the effect of LLLT on the Achilles tendon healing in streptozotocin-induced diabetic (STZ-D) rats via a biomechanical evaluating method. Thirty-three rats were divided into non-diabetic (n?=?18) and diabetic (n?=?15) groups. DM was induced in the rats by injections of STZ. The right Achilles tendons of all rats were tenotomized 1 month after STZ injections. The two experimental groups (n?=?6 for each group) of non-diabetic rats were irradiated with a helium–neon (He–Ne) laser at 2.9 and 11.5 J/cm² for ten consecutive days. The two experimental groups of diabetic rats (n?=?5 for each group) were irradiated with a He–Ne laser at 2.9 and 4.3 J/cm² for ten consecutive days. The tendons were submitted to a tensiometric test. Significant improvements in the maximum stress (MS) values (Newton per square millimeter) were found following LLLT at 2.9 J/cm² in both the non-diabetic (p?=?0.031) and diabetic (p?=?0.019) experimental groups when compared with their control groups. LLLT at 2.9 J/cm² to the tenotomized Achilles tendons in the non-diabetic and diabetic rats significantly increased the strength and MS of repairing Achilles tendons in our study.     

The effects of low-level laser irradiation on cellular viability and proliferation of human skin fibroblasts cultured in high glucose mediums

Delayed wound healing is one of the most challenging complications of diabetes mellitus (DM) in clinical medicine. This study has aimed to evaluate the effects of low-level laser therapy (LLLT) on human skin fibroblasts (HSFs) cultured in a high glucose concentration. HSFs were cultured either in a concentration of physiologic glucose (5.5 mM/l) or high glucose media (11.1 and15?mM/l) for either 1 or 2 weeks after which they were subsequently cultured in either the physiologic glucose or high concentration glucose media during laser irradiation. LLLT was carried out with a helium–neon (He–Ne) laser unit at energy densities of 0.5, 1, and 2 J/cm², and power density of 0.66 mW/cm² on 3 consecutive days. HSFs’ viability and proliferation rate were evaluated with the dimethylthiazol-diphenyltetrazolium bromide (MTT) assay. The LLLT at densities of 0.5 and 1 J/cm² had stimulatory effects on the viability and proliferation rate of HSFs cultured in physiologic glucose (5.5 mM/l) medium compared to their control cultures (p?=?0.002 and p?=?0.046, respectively). All three doses of 0.5, 1, and 2 J/cm² had stimulatory effects on the proliferation rate of HSFs cultured in high glucose concentrations when compared to their control cultures (p?=?0.042, p?=?0.000, and p?=?0.000, respectively). This study showed that HSFs originally cultured for 2 weeks in high glucose concentration followed by culture in physiologic glucose during laser irradiation showed enhanced cell viability and proliferation. Thus, LLLT had a stimulatory effect on these HSFs.     

LLLT improves tendon healing through increase of MMP activity and collagen synthesis

The Achilles tendon has a high incidence of rupture, and the healing process leads to a disorganized extracellular matrix (ECM) with a high rate of injury recurrence. To evaluate the effects of different conditions of low-level laser (LLL) application on partially tenotomized tendons, adult male rats were divided into the following groups: G1, intact; G2, injured; G3, injured + LLL therapy (LLLT; 4 J/cm² continuous); G4, injured + LLLT (4 J/cm², 20 Hz); G5, injured; G6, injured + LLLT (4 J/cm² continuous); and G7, injured + LLLT (4 J/cm², 20 Hz until the 7th day and 2 kHz from 8 to 14 days). G2, G3, and G4 were euthanized 8 days after injury, and G5, G6, and G7 were euthanized on the 15th day. The quantification of hydroxyproline (HOPro) and non-collagenous protein (NCP), zymography for matrix metalloproteinase (MMP)-2 and MMP-9, and Western blotting (WB) for collagen types I and III were performed. HOPro levels showed a significant decrease in all groups (except G7) when compared with G1. The NCP level increased in all transected groups. WB for collagen type I showed an increase in G4 and G7. For collagen type III, G4 presented a higher value than G2. Zymography for MMP-2 indicated high values in G4 and G7. MMP-9 increased in both treatment groups euthanized at 8 days, especially in G4. Our results indicate that the pulsed LLLT improved the remodeling of the ECM during the healing process in tendons through activation of MMP-2 and stimulation of collagen synthesis.     

The influence of low-level laser therapy on parameters of oxidative stress and DNA damage on muscle and plasma in rats with heart failure

In heart failure (HF), there is an imbalance between the production of reactive oxygen species and the synthesis of antioxidant enzymes, causing damage to the cardiovascular function and increased susceptibility to DNA damage. The aim of this study was to evaluate the influence of low-level laser therapy (LLLT) on parameters of oxidative stress and DNA damage in skeletal muscle and plasma of rats with HF. Wistar rats were allocated into six groups: “placebo” HF rats (P-HF, n?=?9), “placebo” Sham rats (P-sham, n?=?8), HF rats at a dose 3 J/cm² of LLLT (3 J/cm²-HF, n?=?8), sham rats at a dose 3 J/cm² of LLLT (3 J/cm²-sham, n?=?8), HF rats at a dose 21 J/cm² of LLLT (21 J/cm²-HF, n?=?8) and sham rats at a dose 21 J/cm² of LLLT (21 J/cm²-sham, n?=?8). Animals were submitted to a LLLT protocol for 10 days at the right gastrocnemius muscle. Comparison between groups showed a significant reduction in superoxide dismutase (SOD) activity in the 3 J/cm²-HF group (p?=?0.03) and the 21 J/cm²-HF group (p?=?0.01) compared to the P-HF group. 2′,7′-Dihydrodichlorofluorescein (DCFH) oxidation levels showed a decrease when comparing 3 J/cm²-sham to P-sham (p?=?0.02). The DNA damage index had a significant increase either in 21 J/cm²-HF or 21 J/cm²-sham in comparison to P-HF (p?=?0.004) and P-sham (p?=?0.001) and to 3 J/cm²-HF (p?=?0.007) and 3 J/cm²-sham (p?=?0.037), respectively. Based on this, laser therapy appears to reduce SOD activity and DCFH oxidation levels, changing the oxidative balance in the skeletal muscle of HF rats. Otherwise, high doses of LLLT seem to increase DNA damage.     

Effects of different fluences of low-level laser therapy in an experimental model of spinal cord injury in rats

The aim of this study was to evaluate the in vivo response of different fluences of low-level laser therapy (LLLT) on the area of the injury, inflammatory markers, and functional recovery using an experimental model of traumatic spinal cord injury (SCI). Thirty two rats were randomly divided into four experimental groups: control group (CG), laser-treated group 500 J/cm² (L-500), laser-treated group 750 J/cm² (L-750), and laser-treated group 1000 J/cm² (L-1000). SCI was performed by an impactor equipment (between the ninth and tenth thoracic vertebrae), with a pressure of 150 kdyn. Afterwards, the injured region was irradiated daily for seven consecutive sessions, using an 808-nm laser, at the respective fluence of each experimental groups. Motor function and tactile sensitivity were performed on days 1 and 7 post-surgery. Animals were euthanized on the eighth day after injury, and the samples were retrieved for histological and immunohistochemistry analyses. Functional evaluation and tactile sensitivity were improved after LLLT, at the higher fluence. Additionally, LLLT, at 750 and 1000 J/cm², reduces the lesion volume and modulates the inflammatory process with decrease of CD-68 protein expression. These results suggest that LLLT at higher doses was effective in promoting functional recovery and modulating inflammatory process in the spinal cord of rats after SCI.     

Effect of low-level laser therapy on odontoblast-like cells exposed to bleaching agent

The aim of the present study was to evaluate the effect of low-level laser therapy (LLLT) on odontoblast-like MDPC-23 cells exposed to carbamide peroxide (CP 0.01 %–2.21 μg/mL of H₂O₂). The cells were seeded in sterile 24-well plates for 72 h. Eight groups were established according to the exposure or not to the bleaching agents and the laser energy doses tested (0, 4, 10, and 15 J/cm²). After exposing the cells to 0.01 % CP for 1 h, this bleaching solution was replaced by fresh culture medium. The cells were then irradiated (three sections) with a near-infrared diode laser (InGaAsP—780?±?3 nm, 40 mW), with intervals of 24 h. The 0.01 % CP solution caused statistically significant reductions in cell metabolism and alkaline phosphate (ALP) activity when compared with those of the groups not exposed to the bleaching agent. The LLLT did not modulate cell metabolism; however, the dose of 4 J/cm² increased the ALP activity. It was concluded that 0.01 % CP reduces the MDPC-23 cell metabolism and ALP activity. The LLLT in the parameters tested did not influence the cell metabolism of the cultured cells; nevertheless, the laser dose of 4 J/cm² increases the ALP activity in groups both with and without exposure to the bleaching agent.     

What is better in TRAM flap survival: LLLT single or multi-irradiation?

Low-level laser therapy (LLLT) has been used with the aim of improving vascular perfusion of the skin and musculocutaneous flaps. This study evaluated the effect of LLLT on transverse rectus abdominis musculocutaneous flap (TRAM) viability, vascular angiogenesis, and VEGF release. Eighty-four Wistar rats were randomly divided into seven groups with 12 rats in each group. Group 1 received sham laser treatment; group 2, 3 J/cm² at 1 point; group 3, 3 J/cm² at 24 points; group 4, 72 J/cm² at 1 point; group 5, 6 J/cm² at 1 point; group 6, 6 J/cm² at 24 points; and group 7, 144 J/cm² at 1 point. All experimental groups underwent LLLT immediately after the TRAM operation and on the following 2 days; thus, animals underwent 3 days of treatment. The percentage of skin flap necrosis area was calculated on the fourth postoperative day using the paper template method, and two skin samples were collected using a 1-cm² punch to evaluate alpha smooth muscle actin (1A4) and VEGF levels in blood vessels. Significant differences were found in necrosis percentage, and higher values were seen in group 1 than in the other groups. Statistically significant differences were not found among groups 3 to 7 (p?<?0.292). Groups 5 and 7 showed significantly higher VEGF levels compared to other groups. Groups 3 and 5 had an increase in levels of blood vessels compared to other groups. LLLT at energy densities of 6 to 144 J/cm² was efficient to increase angiogenesis and VEGF levels and promote viability in TRAM flaps in rats.     

Effects of equal daily doses delivered by different power densities of low-level laser therapy at 670 nm on open skin wound healing in normal and corticosteroid-treated rats: a brief report

The optimal parameters for low-level laser therapy (LLLT) for wound healing are still open to discussion. Hence, our study was aimed at comparing the effects of different power densities of LLLT at 670 nm in rats. Four round full-thickness skin wounds were placed on the backs of 16 rats which were divided into two groups (non-steroid and steroid-treated). Three wounds were stimulated daily with a diode laser (daily dose 5 J/cm²) at different power densities (5, 15 and 40 mW/cm², respectively), and the fourth wound served as a control. Six days after surgery all animals were killed and samples removed for histological evaluation. Significant acceleration of fibroblast proliferation and new vessel formation was observed in wounds treated at the selected power densities. No significant differences were found in corticosteroid-treated rats. In conclusion, LLLT with the methodology used improved wound healing in non-steroid rats, but was not effective after corticosteroid-treatment.     

Comparative analysis of low-level laser therapy (660 nm) on inflammatory biomarker expression during the skin wound-repair process in young and aged rats

The wound-healing process plays an essential role in the protective response to epidermal injury by tissue regeneration. In the elderly, skin functions deteriorate as a consequence of morphological and structural changes. This study aimed to evaluate and compare the effect of low-level laser therapy (LLLT) in cutaneous wound healing in young and aged rats. A total of 60 male rats comprising 30 young (±30 days) and 30 aged (±500 days) was used. The animals were divided into four experimental groups and underwent skin wound and/or treatment with LLLT (660 nm, 30 mW, 1.07 W/cm², 0.028 cm², 72 J/cm², and 2 J). Analyses were conducted to verify the effects of LLLT in the tissue repair process, in the gene expression, and protein expression of TNF-α, IL-1β, and IL-10, obtained in skin wound model. Results showed that there were significant differences between the young control group and the aged control group and their respective treated groups (LLLT young and LLLT aged). We conclude that LLLT has shown to be effective in the treatment of skin wounds in young and aged animals at different stages of the tissue repair process, which suggests that different LLLT dosimetry should be considered in treatment of subjects of different ages. Further clinical trials are needed to confirm these findings in clinical settings.     

LLLT for the management of patients with ankylosing spondylitis

This study aimed to compare the effectiveness of the combined low-level laser therapy (LLLT) and passive stretching with combined placebo LLLT laser and the same passive stretching exercises in patients suffering from Αnkylosing spondylitis. Forty-eight patients suffering from Αnkylosing spondylitis participated in the study and were randomized into two groups. Group A (n?=?24) was treated with a λ?=?820 Ga-Al-As laser CW, with power intensity?=?60 mW/cm², energy per point in each session?=?4.5 J, total energy per session?=?27.0 J, in contact with specific points technique, plus passive stretching exercises. Group B (n?=?24), received placebo laser plus the same passive stretching exercises. Both groups received 12 sessions of laser or placebo within 8 weeks; two sessions per week (weeks 1–4) and one session per week (weeks 5–8). Pain and function scales were completed before the treatment, at the end of the fourth and eighth week of treatment, and 8 weeks after the end of treatment (follow-up). Group A revealed a significant improvement after 8 weeks of treatment in all pain and function scales. At 8-week follow-up, the improvement remained only for the pain, while for all other function outcomes the differences were not statistically significant. The results suggested that after an 8-week treatment and after a follow-up, the combination of LLLT and passive stretching exercises decreased pain more effectively than placebo LLLT along with the same passive stretching exercises in patients with Αnkylosing spondylitis. Future studies are needed to establish the relative and absolute effectiveness of the above protocol.     

Long-term low-level laser therapy promotes an increase in maximal oxygen uptake and exercise performance in a dose-dependent manner in Wistar rats

The use of low-level laser therapy (LLLT) represents a new intervention modality that has been explored to enhance exercise performance. The aim of this study was to evaluate the influence of LLLT (GaAIAs—850 nm) at different doses on VO_2max and on exercise performance in rats. Male Wistar rats were divided into three groups: “placebo” rats (P-LLLT, n?=?10), rats at a dose of 0.315 J per treatment point of LLLT (8.7 J/cm²-LLLT, n?=?10), and rats at a dose of 2.205 J per treatment point of LLLT (61.2 J/cm²-LLLT, n?=?10). The LLLT was applied bilaterally at the biceps femoris, gluteus, lateral and medial gastrocnemius, iliopsoas, and adductor longus muscles. One spot in each muscle belly was applied, with a sum of 12 spots in each rat, once a day, for 10 days. All animals performed the maximal exercise test (ET) at a metabolic treadmill for rats, with simultaneous gas analysis. The distance covered was measured during ET, before and after the conclusion of the LLLT protocol. The data were compared by a repeated measures two-way ANOVA followed by the Student-Newman-Keuls post hoc tests (p?<?.05). The 61.2 J/cm²-LLLT group increased VO_2basal (~40 %), VO_2max (~24 %), VCO_2max (~17 %), and distance covered (~34 %) after LLLT application on the skeletal muscle. No significant results were found comparing before and after conditions for the studied variables considering P-LLLT and 8.7 J/cm²-LLLT groups. The LLLT promoted in a dose-dependent manner an increase in oxygen consumption uptake and a performance increment of male Wistar rats.     

Infrared low-level diode laser on serum chemokine MCP-1 modulation in mice

The effect of the low-level laser therapy (LLLT) in the modulation of cells related to inflammatory processes has been widely studied, with different parameters. The objective was to investigate the immediate and cumulative effect of infrared LLLT on chemokine monocyte chemotactic protein-1 (MCP-1) modulation in mice. Fifty-two isogenic mice were distributed in seven groups: control (n?=?10, no surgical procedure), laser I (n?=?7, surgical procedure and a single LLLT exposure 12 h after the surgery), laser II (n?=?7, surgery followed by two LLLT exposures, 12 and 36 h after surgery), and laser III (n?=?7, surgery followed by three LLLT exposures, 12, 36, and 60 h after surgery). For each group, a sham group (n?=?21) underwent surgery without laser application. The animals in the laser groups received an infrared diode continuous laser exposure (AsGaAl, 780 nm wavelength, power of 20 mW, energy density of 10 J/cm², spot size of 0,04 cm²) on three points (20 s per point), and a final energy of 0.4 J. The animals were sacrificed 36 h (laser I and sham I groups), 60 h (laser II and sham II), and 84 h (laser III and sham III groups) after surgery. The MCP-1 concentrations were measured by cytometric bead array. There was no significant difference between the three periods in the sham group (p?=?0.3). There was a lower concentration of MCP-1 in the laser III group compared to the laser I group (p?=?0.05). The infrared LLLT showed a cumulative effect in the modulation of chemokine MCP-1 concentration. Three LLLT exposures were necessary to achieve the MCP-1 modulation.     

Effect of low-level laser therapy on angiogenesis and matrix metalloproteinase-2 immunoexpression in wound repair

Low-level laser therapy (LLLT) induces anti-inflammatory and angiogenic activities in wound healing. However, the mechanism of action and optimal parameters require further clarification. In this study, we investigated the effects of LLLT on wound healing matrix metalloproteinase (MMP)-2 immunoexpression and angiogenic processes. Twenty female Wistar rats were randomly divided into four groups (n?=?5) according to the treatments as follows. CG7 and CG14 were control groups at days 7 and 14, respectively, which received physiological saline (0.9 % NaCl daily). LG7 and LG14 were laser therapy groups at days 7 and 14, respectively, which received two (LG7) or four (LG14) LLLT applications (40 mW; 660 nm; 4 J/cm²). A dorsal skin sample in the wound area (measuring 2 cm²) was removed after the experimental period, and then the animals were euthanized. The specimens were processed for qualitative and quantitative histological analyses and measurement of MMP-2 expression in the dermis and epidermis. A persistent crust and moderate number of inflammatory cells were found in CG7 and CG14 groups. In the LG14 group, wounds demonstrated complete re-epithelization at the remodeling phase. Angiogenesis and MMP-2 expression were higher in LLLT-treated groups, particularly the LG14 group, which correlated according to the Spearman correlation test. LLLT improves wound healing by enhancing neocollagenesis, increasing the amount of new vessels formed in the tissue (neoangiogenesis), and modulating MMP-2 expression. Epidermal overexpression of MMP-2 was correlated to angiogenic processes.     

Low-level laser therapy prevents degenerative morphological changes in an experimental model of anterior cruciate ligament transection in rats

The aim of this study was to analyze the effects of low-level laser therapy (LLLT) on the prevention of cartilage damage after the anterior cruciate ligament transection (ACLT) in knees of rats. Thirty male rats (Wistar) were distributed into three groups (n?=?10 each): injured control group (CG); injured laser-treated group at 10 J/cm² (L10), and injured laser-treated group at 50 J/cm² (L50). Laser treatment started immediately after the surgery and it was performed for 15 sessions. An 808 nm laser, at 10 and 50 J/cm², was used. To evaluate the effects of LLLT, the qualitative and semi-quantitative histological, morphometric, and immunohistochemistry analysis were performed. Initial signs of tissue degradation were observed in CG. Interestingly, laser-treated animals presented a better tissue organization, especially at the fluence of 10 J/cm². Furthermore, laser phototherapy was able of modulating some of the aspects related to the degenerative process, such as the prevention of proteoglycans loss and the increase in cartilage area. However, LLLT was not able of modulating chondrocytes proliferation and the immunoexpression of markers related to inflammatory process (IL-1 and MMP-13). This study showed that 808 nm laser, at both fluences, prevented features related to the articular degenerative process in the knees of rats after ACLT.     

Low-level laser therapy improves the inflammatory profile of rats with heart failure

Following heart failure (HF), immune activation leads to an imbalance between pro-inflammatory and anti-inflammatory cytokines. Low-level laser therapy (LLLT) has been used as an anti-inflammatory treatment in several disease conditions. However, the effect of LLLT on the skeletal muscle of rats with HF remains unclear. The present report aimed to evaluate the influence of LLLT on the inflammatory profile of rats with HF. The left coronary artery was ligated to induce HF and a sham operation was performed in the control groups. Male Wistar rats (n?=?49) were assigned to one of six groups: placebo sham rats (P-Sham; n?=?8), LLLT at a dose of 3 J/cm² sham rats (3 J/cm²-Sham; n?=?8), LLLT at a dose of 21 J/cm² sham rats (21 J/cm²-Sham; n?=?8), placebo HF rats (P-HF; n?=?9), LLLT at a dose of 3 J/cm² HF rats (3 J/cm²-HF; n?=?8), and LLLT at a dose of 21 J/cm² HF rats (21 J/cm²-HF; n?=?8). Four weeks after myocardial infarction or sham surgery, rats were subjected to LLLT (InGaAlP 660 nm, spot size 0.035 cm², output power 20 mW, power density 0.571 W/cm², energy density 3 or 21 J/cm², exposure time 5.25 s and 36.75 s) on the right gastrocnemius for 10 consecutive days. LLLT reduced plasma IL-6 levels (61.3 %; P?<?0.01), TNF-α/IL-10 (61.0 %; P?<?0.01) and IL-6/IL-10 ratios (77.3 %; P?<?0.001) and increased IL-10 levels (103 %; P?<?0.05) in the 21 J/cm²-HF group. Moreover, LLLT reduced the TNF-α (20.1 % and 21.3 %; both P?<?0.05) and IL-6 levels (54.3 % and 37.8 %; P?<?0.01 and P?<?0.05, respectively) and the IL-6/IL-10 ratio (59.7 % and 42.2 %; P?<?0.001 and P?<?0.05, respectively) and increased IL-10 levels (81.0 % and 85.1 %; both P?<?0.05) and the IL-10/TNF-α ratio (171.5 % and 119.8 %; P?<?0.001 and P?<?0.05, respectively) in the gastrocnemius in the 3 J/cm²-HF and 21 J/cm²-HF groups. LLLT showed systemic and skeletal muscle anti-inflammatory effects in rats with HF.     

Combined effects of low-level laser therapy and human bone marrow mesenchymal stem cell conditioned medium on viability of human dermal fibroblasts cultured in a high-glucose medium

Low-level laser therapy (LLLT) exhibited biostimulatory effects on fibroblasts viability. Secretomes can be administered to culture mediums by using bone marrow mesenchymal stem cells conditioned medium (BM-MSCs CM). This study investigated the combined effects of LLLT and human bone marrow mesenchymal stem cell conditioned medium (hBM-MSCs CM) on the cellular viability of human dermal fibroblasts (HDFs), which was cultured in a high-glucose (HG) concentration medium. The HDFs were cultured either in a concentration of physiologic (normal) glucose (NG; 5.5 mM/l) or in HG media (15 mM/l) for 4 days. LLLT was performed with a continuous-wave helium-neon laser (632.8 nm, power density of 0.00185 W/cm² and energy densities of 0.5, 1, and 2 J/cm²). About 10 % of hBM-MSCs CM was added to the HG HDF culture medium. The viability of HDFs was evaluated using dimethylthiazol-diphenyltetrazolium bromide (MTT) assay. A significantly higher cell viability was observed when laser of either 0.5 or 1 J/cm² was used to treat HG HDFs, compared to the control groups. The cellular viability of HG-treated HDFs was significantly lower compared to the LLLT?+?HG HDFs, hBM-MSCs CM-treated HG HDFs, and LLLT?+?hBM-MSCs CM-treated HG HDFs. In conclusion, hBM-MSCs CM or LLLT alone increased the survival of HG HDFs cells. However, the combination of hBM-MSCs CM and LLLT improved these results in comparison to the conditioned medium.     

Evaluation of low-level laser therapy,platelet-rich plasma,and their combination on the healing of Achilles tendon in rabbits

Tendon repair is still one of the challenges for rehabilitation. Various treatments for tendon injuries have been used in recent decade. This study was established to investigate the effects of low-level laser therapy (LLLT), platelet-rich plasma (PRP) treatment alone, and using combined method on the healing of Achilles tendon in rabbits. Seventy-two healthy mature male white New Zealand rabbits were divided randomly into four groups of 18 animals each: control: partial tenotomy with no treatment, only 1 mL normal saline was injected on days 1, 8, and 15 at the site of splitting; PRP: partial tenotomy with PRP treatment on days 1, 8, and 15 at the site of splitting; LLLT: partial tenotomy with LLLT (K30 hand-held probe, AZOR, Technica, Russia, 650 nm, 30 mW, surface area?=?1 cm², 60 S/cm², energy density?=?1.8 J/cm²) for 15 consecutive days; LLLT?+?PRP: partial tenotomy with LLLT?+?PRP. At the end of trial, the rabbits were euthanatized and tendon specimens were harvested and were submitted for histopathological evaluation, hydroxyproline levels, and biomechanical measurement. The Tukey post hoc test was performed. The results for these parameters showed that PRP or LLLT alone has significant advantages over untreated animals (P?<?0.05). Furthermore, it was found that the combined treatment with PRP and LLLT is even more efficient. There was no significant difference (P?>?0.05) between the two groups of LLLT and PRP. However, the treatments combining PRP and LLLT showed significant results in comparison of PRP or LLLT alone (P?<?0.05). Our results demonstrate that the healing time of injured tendon decreases by using the two therapies combined.