Systemic and local inflammatory response after implantation of biomaterial in critical bone injuries.

PURPOSE: To evaluate inflammatory response in critical bone injuries after implantation of the biomaterial composed of hydroxyapatite (HA)/poly (lactic-coglycolic acid) (PLGA)/BLEED. METHODS: Forty-eight male Wistar rats (280 ± 20 grams) were divided into two groups: control group (CG), in which the animals do not receive any type of treatment; and biomaterial group (BG), in which the animals received the HA/PLGA/BLEED scaffold. Critical bone injury was induced in the medial region of the skull calotte with the aid of a trephine drill 8 mm in diameter. The biomaterial was implanted in the form of 1.5-mm thick scaffolds. Serum and calotte were collected at one, three and seven days. RESULTS: Biomaterial had a significant effect on the morphological structure of the bone, accelerating osteoblast activation within three days, without causing exacerbated systemic inflammation. In addition, quantitative real-time polymerase chain reaction (qRT-PCR) analysis showed that BG induced upregulation of osteogenic genes such as runt-related transcription factor 2, and stimulated genes of inflammatory pathways such as tumor necrosis factor-α, on the first day without overexpressing genes related to bone matrix degradation, such as tissue inhibitor of metalloproteinases-1 and matrix metalloproteinase-9. CONCLUSIONS: The HA/PLGA/BLEED® association can be used as a bone graft to aid bone repair, as it is capable of modulating expression of important genes at this stage of the repair process.

The Effects of Electrode Placement on Analgesia Using Transcutaneous Electrical Nerve Stimulation for Primary Dysmenorrhea: A Single-Blind Randomized Controlled Clinical Trial.

Background Primary dysmenorrhea (PD) refers to the occurrence of painful menstrual cramps without pathological involvement of the pelvic organs, with considerable morbidity and high prevalence among females of reproductive age. Objective The objective of this study is to present and test the efficacy of an innovative method of interactive transcutaneous electrical nerve stimulation (iTENS) for PD. Methods and materials This study is a single-blind controlled clinical trial. This was conducted at the outpatient clinic of the faculty of physical therapy. Females with PD (n=124) were divided into the treated group (transcutaneous electrical nerve stimulation {TENS} group {TG}, n=62) and the placebo group (PG, n=62). A single session of either iTENS or placebo intervention was used for 35 minutes. Pain, the duration of analgesia, and the use of pain medication were assessed before and after the intervention. Data from before and after the treatment were compared between groups (Student's t-test). The level of significance was set at 5%. Results A significant decrease in pain (p<0.001) was observed after the intervention for the TG, with a more long-lasting analgesia (p<0.001) and decreased need for pain medication (p<0.001). Conclusions The proposed method of transcutaneous electrical nerve stimulation (TENS) application showed positive results for pain management on females with PD, with no reported adverse effects. The new proposed TENS application takes into account the preferences of the patient regarding positioning and the number of channels needed to cause analgesia. This application was able to promote almost complete analgesia in females with primary dysmenorrhea, and the analgesia persisted for more than one menstrual cycle.

Systemic and local inflammatory response after implantation of biomaterial in critical bone injuries

Purpose: To evaluate inflammatory response in critical bone injuries after implantation of the biomaterial composed of hydroxyapatite (HA)/poly (lactic-coglycolic acid) (PLGA)/BLEED. Methods: Forty-eight male Wistar rats (280 ± 20 grams) were divided into two groups: control group (CG), in which the animals do not receive any type of treatment; and biomaterial group (BG), in which the animals received the HA/PLGA/BLEED scaffold. Critical bone injury was induced in the medial region of the skull calotte with the aid of a trephine drill 8 mm in diameter. The biomaterial was implanted in the form of 1.5-mm thick scaffolds. Serum and calotte were collected at one, three and seven days. Results: Biomaterial had a significant effect on the morphological structure of the bone, accelerating osteoblast activation within three days, without causing exacerbated systemic inflammation. In addition, quantitative real-time polymerase chain reaction (qRT-PCR) analysis showed that BG induced upregulation of osteogenic genes such as runt-related transcription factor 2, and stimulated genes of inflammatory pathways such as tumor necrosis factor-α, on the first day without overexpressing genes related to bone matrix degradation, such as tissue inhibitor of metalloproteinases-1 and matrix metalloproteinase-9. Conclusions: The HA/PLGA/BLEED® association can be used as a bone graft to aid bone repair, as it is capable of modulating expression of important genes at this stage of the repair process.

Fast inactivation of coronavirus in filtering-facepiece respirators in a reflective cylindrical UV-C chamber.

Objective: We report on the development and characterization of a UV-C (λ  =  200 - 280 nm, λpeak = 254 nm) chamber designed for the rapid disinfection of N95 class filtering-facepiece respirators contaminated with SARS-CoV-2 coronaviruses. The device was evaluated against Betacoronavirus strain MHV-3 and its virucidal capacity was evaluated as a function of different applied UV-C doses (UV-C exposure times of 60 s, 120 s, 180 s, and 240 s) using two types of respirators geometry (shell and two-panel shapes, 3M 8801 H and 9920 H, respectively), at eight points of the respirators. Background: Most chemical disinfection methods are not recommended for N95 masks. UV-C light provided by UVGI lamps (254 nm) is an effective physical agent against viruses and bacteria due to direct photochemical harming effect on DNA/RNA, and can provide rapid disinfection for personal protective equipment such as N95/PFF2 masks. Results: The device reached a mean elimination rate of 99.9999% of MHV-3 inoculated into all the assessed different points on the tested PFF2 respirator models in a UV-C cycle of just 60 s. Statistical analysis performed through Person´s chi-square test showed no correlation between the viral infectivity reduction and the viral inoculation point (p = 0.512) and the tested respirator models (p = 0.556). However, a correlation was found between the exposure time and the viral infectivity reduction (p = 0.000*), between UV-C and no UV-C exposure. All the tested UV-C exposure times (60 s, 120 s, 180 s, and 240 s) provided the same reduction in infection rates. Therefore, 60 s was confirmed as the minimum exposure time to achieve a 99.9999% or 6 Log reduction in MHV-3 coronavirus infection rates in the PFF2 samples tested in the device. Conclusions: We conclude that the assessed UV-C chamber for the inactivation of MHV-3 coronavirus in N95/PFF2 standard masks can be a promising tool for effective and rapid disinfection of coronaviruses, including SARS-CoV-2 virus.

Comparison of two different biomaterials in the bone regeneration (15, 30 and 60 days) of critical defects in rats.

PURPOSE: To evaluate and compare two types of different scaffolds in critical bone defects in rats. METHODS: Seventy male Wistar rats (280 ± 20 grams) divided into three groups: control group (CG), untreated animals; biomaterial group 1 (BG1), animals that received the scaffold implanted hydroxyapatite (HA)/poly(lactic-co-glycolic) acid (PLGA); and biomaterial group 2 (BG2), animals that received the scaffolds HA/PLGA/Bleed. The critical bone defect was induced in the medial region of the skull calotte with the aid of an 8-mm-diameter trephine drill. The biomaterial was implanted in the form of 1.5 mm thick scaffolds, and samples were collected after 15, 30 and 60 days. Non-parametric Mann-Whitney test was used, with the significance level of 5% (p ≤ 0.05). RESULTS: Histology revealed morphological and structural differences of the neoformed tissue between the experimental groups. Collagen-1 (Col-1) findings are consistent with the histological ones, in which BG2 presented the highest amount of fibers in its tissue matrix in all evaluated periods. In contrast, the results of receptor activator of nuclear factor kappa-Β ligand (Rank-L) immunoexpression were higher in BG2 in the periods of 30 and 60 days, indicating an increase of the degradation of the biomaterial and the remodeling activity of the bone. CONCLUSIONS: The properties of the HA/PLGA/Bleed scaffold were superior when compared to the scaffold composed only by HA/PLGA.

Comparison of two different biomaterials in the bone regeneration (15, 30 and 60 days) of critical defects in rats

ABSTRACT Purpose To evaluate and compare two types of different scaffolds in critical bone defects in rats. Methods Seventy male Wistar rats (280 ± 20 grams) divided into three groups: control group (CG), untreated animals; biomaterial group 1 (BG1), animals that received the scaffold implanted hydroxyapatite (HA)/poly(lactic-co-glycolic) acid (PLGA); and biomaterial group 2 (BG2), animals that received the scaffolds HA/PLGA/Bleed. The critical bone defect was induced in the medial region of the skull calotte with the aid of an 8-mm-diameter trephine drill. The biomaterial was implanted in the form of 1.5 mm thick scaffolds, and samples were collected after 15, 30 and 60 days. Non-parametric Mann-Whitney test was used, with the significance level of 5% (p ≤ 0.05). Results Histology revealed morphological and structural differences of the neoformed tissue between the experimental groups. Collagen-1 (Col-1) findings are consistent with the histological ones, in which BG2 presented the highest amount of fibers in its tissue matrix in all evaluated periods. In contrast, the results of receptor activator of nuclear factor kappa-Β ligand (Rank-L) immunoexpression were higher in BG2 in the periods of 30 and 60 days, indicating an increase of the degradation of the biomaterial and the remodeling activity of the bone. Conclusions The properties of the HA/PLGA/Bleed scaffold were superior when compared to the scaffold composed only by HA/PLGA.

Biphasic Dose/Response of Photobiomodulation Therapy on Culture of Human Fibroblasts.

Objective: The objective of this study was to evaluate the effects of application of different fluences and energies of laser in the 24-, 48-, and 72-h periods in fibroblasts originating from human skin (HFF-1). Methods: The cell used as a template for cell proliferation was HFF-1. For the photobiomodulation (PBM) application, a 660 nm laser with a power of 40 mW and energies of 0.84, 1.40, 5.88, and 6.72 J was used. Five experimental groups were studied: one control group (CG) with simulated PBM and four groups that received PBM in different doses. The changes observed after laser irradiation were evaluated by cell viability (trypan blue) and proliferation [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)] tests. Intergroup comparisons were performed using two-way analysis of variance and the Tukey post hoc test (software GraphPad Prism 7.0). Results: In the trypan blue test, the total number of cells was significantly different between the irradiated groups and the CG at all times studied. The total number of cells increased in laser group (LG)1 (0.84 J) and LG2 (1.40 J) and decreased in LG4 (6.72 J). The mitochondrial activity increased significantly in LG1 and LG2 at 48 and 72 h and decreased in LG3 (5.88 J) and LG4 (6.72 J) compared with CG. Conclusions: The results indicate that the lower doses (0.45 and 0.75 J/cm2) of PBM induce the highest mitochondrial activity and cellular viability.

Inflammatory response and macrophage polarization using different physicochemical biomaterials for oral and maxillofacial reconstruction.

Knowledge about the action of immune system in the recognition of biomaterials has been extremely helpful when it comes about understanding host response and biomaterials' fate in human body. This study aimed to investigate inflammatory response and macrophage polarization during bone healing process of rat's calvaria critical defects using different bone materials in order to evaluate their influence on bone repair and on the quality of the newly formed bone tissue. Eighty male albinus Wistar rats underwent surgical procedure for the confectioning of a 5-mm diameter bone defect in their right parietal bone, and divided in four groups (n = 20 each), according the biomaterial: AG - Control, particulate intramembranous autogenous bone graft, HA/TCP - particulate biphasic calcium phosphate with HA/TCP (60/40), DBB - particulate deproteinized bovine bone, VC - particulate bioactive vitroceramic. After 3, 7, 21, and 45 days, the specimens were removed and prepared for microcomputed tomography (microCT), light and polarized microscopy, immunohistochemical analysis, and histomorphometry. No significant differences were detected considering percentage of leukocytes among the groups and periods, as well as in relation to immunolabeling for inflammatory (M1) and reparative (M2) macrophages. However, immunolabeling for bone marker indicated a delayed osteoblast differentiation in VC group, resulting in a decrease in mineralized bone matrix parameters in this group, revealed by microCT. In addition, AG and HA/TCP presented a satisfactory bone collagenous content. Despite the distinct origins and physicochemical properties of the tested biomaterials, they presented similar immune-inflammatory responses in the present experimental model, influencing bone-related proteins and bone quality, which must be considered according to their use.

Photobiomodulation on critical bone defects of rat calvaria: a systematic review.

Bone defects following trauma represent a high impact on the quality of life of millions of people around the world. The aim of this study was to review photobiomodulation (PBM) action in the treatment of bone critical defects in rat calvaria, related to evaluation of the current protocols applied. One hundred and forty-seven articles related to the subject were found by searching the main databases (Pubmed, Lilacs, Web of Science, and Scopus) considering the period of publication until the year 2017, and only 14 corresponded the inclusion criteria established for this systematic review. The main parameters of the PBM were expressed in Table 1. In addition, it was possible to observe the use of two different wavelengths (red and infrared), which are considered therapeutic. Most of the evaluated articles presented positive results that describe a greater amount of neoformed bone, an increase in collagen synthesis, and a contribution to microvascular reestablishment. However, two studies report no effect on the repair process when the PBM was used. In addition, we observed considerable variations between the values of power, fluence, and total energy, which make it difficult to compare the results presented between the selected studies. It was possible to conclude that the infrared laser was more effective in positively stimulating the bone repair process of critical defects. Furthermore, a discrepancy was found in the parameter values used, which made it difficult to choose the best protocol for the treatment of this type of lesion.

Photobiomodulation and bacterial cellulose membrane in the treatment of third-degree burns in rats.

Burns are injuries caused mainly by thermal trauma, which can progress to unsatisfactory results healing. This study aimed to evaluate the biomaterial (bacterial cellulose membrane) and photobiomodulation, exclusively and associated, in the treatment of third degree burns in rats. Forty male Wistar rats (±280 g) were randomly divided into four groups, with 10 animals each: control group (CG); bacterial cellulose membrane group (MG); laser group (LG) and bacterial cellulose membrane and laser group (MG + L). The burn was caused with a 1 cm2 aluminum plate heated to 150 °C and pressed on the animal's back for 10 s. The treatments were started immediately after induction of injury. For to laser irradiation (660 nm, 100 mW, 25 J/cm2 and energy of 1 J) on five distinct application points were used, on alternate days, a total of five sessions. After ten days of treatment the animals were euthanized for collected samples. One-way ANOVA and Tukey's tests (P < 0.05) were used. Histological analysis revealed differences regarding the healing process phase in each experimental group. MG showed the proliferative phase. The LG demonstrated greater amount of blood vessels and immune expression of VEGF. However, when the treatments were combined, the number of vessels and the immune expression of VEGF factor was lower than LG. Thus, it was concluded that both treatments proposed (biomaterial and LLLT) are good alternatives for third degree burns when applied isolated because they stimulate the healing process by acting on the modulation of the inflammatory phase and promote stimulation of angiogenesis.

Evaluation of the low-level laser therapy application parameters for skin burn treatment in experimental model: a systematic review.

Burn is defined as a traumatic injury of thermal origin, which affects the organic tissue. Low-level laser therapy (LLLT) has gained great prominence as a treatment in this type of injury; however, the application parameters are still controversial in the literature. The aims of this study were to review the literature studies that use LLLT as a treatment in burns conducted in an experimental model, discuss the main parameters used, and highlight the benefits found in order to choose an appropriate therapeutic window to be applied in this type of injury. The selection of the studies related to the theme was carried out in the main databases (PubMed, Cochrane Library, LILACS, Web of Science, and Scopus in the period from 2001 to 2017). Subsequently, the articles were then chosen that fell within the inclusion criteria previously established. In the end, 22 were evaluated, and the main parameters were presented. The analyzed studies presented both LLLT use in continuous and pulsed mode. Differences between the parameters used (power, fluence, and total energy) were observed. In addition, the protocols are distinct as to the type of injury and the number of treatment sessions. Among the results obtained by the authors are the improvements in the local microcirculation and cellular proliferation; however, a study reported no effects with LLLT as a treatment. LLLT is effective in accelerating the healing process. However, there is immense difficulty in establishing the most adequate protocol, due to the great discrepancy found in the applied dosimetry values.

Bacterial cellulose membrane used as biological dressings on third-degree burns in rats.

INTRODUCTION: Burn injuries represent a high risk of morbidity and mortality. The wound healing process is complex and requires the participation of different types of cells. Therefore, new biomaterials, which innovate the wound healing process, are being investigated. OBJECTIVE: The aim of this study was to investigate the use of bacterial cellulose both in its pure state and enriched with lidocaine in full-thickness burns in rats. METHODS: Thirty rats (Wistar) (260 ± 20 gramas) divided into control group (CG), bacterial cellulose membrane group (MG) and bacterial cellulose membrane enriched with lidocaine group (MLG) were used. The burns were induced using a 150°C heated soldering iron, held on the animal neck for 10 seconds. The biomaterial was applied immediately after injury and skin samples were collected on the tenth day of the treatment. The level of significance of p⩽0.05 was used for the conclusion of the statistical analysis. RESULTS: The groups treated with the biomaterials, a histological pattern compatible with a more advanced repair stage showing skin appendages, mild inflammatory infiltrate, better collagen fiber organization and mild immunostaining COX-2 and MMP-9 was observed, when compared to the control group that did not receive any type of treatment. CONCLUSION: Thus, was concluded that the bacterial cellulose-based biomaterial both in its pure state and enriched with lidocaine optimizing the full-thickness burn wound healing in rats.

Effect of photobiomodulation therapy (808 nm) in the control of neuropathic pain in mice.

Neuropathic pain can be defined as the pain initiated or caused by a primary lesion or dysfunction of the central or peripheral nervous system. Photobiomodulation therapy (PBM) stands out among the physical therapy resources used for analgesia. However, application parameters, especially the energy density, remain controversial in the literature. Therefore, this study aimed to investigate the PBM effect, in different energy densities to control neuropathic pain in mice. Fifty (50) mice were induced to neuropathy by chronic constriction surgery of the sciatic nerve (CCI), treated with PBM (808 nm), and divided into five groups: GP (PBM simulation), GS (sham), GL10, GL20, GL40 (energy density of 10, 20, and 40 J/cm2, respectively). The evaluations were carried out using the hot plate test and Randall and Selitto test, before and after the CCI surgery, every 15 days during the 90 days experiment. ß-Endorphin blood dosage was also tested. For both the hot plate and Randall and Selitto tests, the GL20 and GL40 groups presented reduction of the nociceptive threshold from the 30th day of treatment, the GL10 group only after day 75, and the GP group did not show any improvement throughout the experiment. The ß-endorphin dosage was higher for all groups when compared to the GP group. However, only the GL20 group and GL40 presented a significant increase. This study demonstrates that PBM in higher energy density (20, 40 J/cm2) is more effective in the control of neuropathic pain.

Low-level laser therapy induces an upregulation of collagen gene expression during the initial process of bone healing: a microarray analysis.

This study investigates the histological modifications produced by low level laser therapy (LLLT) on the first day of bone repair, as well as evaluates the LLLT effects on collagen expression on the site of a fracture. Twenty Wistar rats were distributed into a control group (CG) and a laser group (LG). Laser irradiation of Ga-Al-As laser 830 nm, 30 mW, 94 s, 2.8 J was performed in five sessions. Animals were euthanized on day 5 postsurgery. Histopathological analysis showed that LLLT was able to increase deposition of granulation tissue and newly formed bone at the site of the injury. In addition, picrosirius analysis showed that collagen fiber organization in the LG was enhanced compared to CG. Microarray analysis demonstrated that LLLT produced an upregulation type I collagen (COL-I). Immunohistochemical analysis revealed that the subjects that were treated presented a higher immunoexpression of COL-I. Our findings indicated that LLLT improves bone healing by producing a significant increase in the expression of collagen genes.

Effects of Low-Level Laser Therapy Applied Before Treadmill Training on Recovery of Injured Skeletal Muscle in Wistar Rats.

OBJECTIVE: The aim of this study was to analyze the effects of low-level laser therapy (LLLT) when associated with treadmill training on the recovery of skeletal muscle, during two periods of rest after muscle injury in rats. BACKGROUND DATA: Because of photostimulation, LLLT has been presented as an alternative for accelerating the tissue healing process. MATERIALS AND METHODS: Forty rats were divided into two groups (A and B) containing four subgroups each: GC (Control Group)-cryolesion untreated; EG (Exercise Group)-cryolesion treated with physical exercise; LG (Laser Group)-cryolesion treated with laser; ELG (Exercise and Laser Group)-cryolesion treated with laser and physical exercise. The right tibialis anterior (TA) of the middle belly was injured by a cooling iron bar (cryoinjury). Group A remained at rest for 3 days, whereas Group B remained at rest for 7 days. The laser parameters utilized were 780 nm with 15 mW average optical power and spot size of 0.04 cm(2) applied during 10 sec, leading to 0.152 J and 3.8 J/cm(2). Treadmill training with and without laser application was performed during 5 days, with each session lasting for 12 min at a velocity of 17 m/min. Subsequently, the TA muscle was removed for a histological and morphometric analysis. RESULTS: The damaged area was significantly smaller for the ELG at both periods of rest, 3 and 7 days, respectively (4.4 ± 0.42% and 3.5 ± 0.14%, p < 0.05), when compared with the LG (18.6 ± 0.64% and 7.5 ± 0.13%), the EG (21 ± 0.26% and 8.7 ± 0.32%), and the CG (23.9 ± 0.37% and 21.4 ± 0.38%). In addition, the number of blood vessels were significantly higher for the ELG at both periods of rest, 3 and 7 days, respectively (71.2 ± 13.51 and 104.5 ± 11.78, p < 0.05), when compared with the LG (60.6 ± 11.25 and 93.5 ± 16.87), the EG (51.6 ± 7.3 and 93.8 ± 15.1) and the CG (34.4 ± 2.54 and 65.7 ± 14.1). CONCLUSIONS: The LLLT applied before the physical exercise on the treadmill stimulated the angiogenesis and accelerated the process of muscle recovery.

Comparative effects of two different doses of low-level laser therapy on wound healing third-degree burns in rats.

Burns are injuries caused by direct or indirect contact to chemical, physical, or biological agents. Low-level laser therapy (LLLT) is a promising treatment since it is low-cost, non-invasive, and induces cell proliferation. This study aimed to investigate the effects of LLLT (660 nm) at two different fluences (12.5 J/cm(2) and 25 J/cm(2) ) per point of application on third-degree burns in rats. Thirty rats (Wistar) divided into GC, GL12.5, and GL25 were used in the study, and submitted to burn injury through a soldering iron at 150°C, pressed on their back for 10 s. LLLT was applied immediately, and 2, 4, 6, and 8 days after wound induction. Histological analysis revealed a decreased inflammatory infiltrate in the group treated with 25 J/cm(2) , and intense inflammatory infiltrate in the control group and in the group treated with 12.5 J/cm(2) . The immunostaining of COX-2 was more intense in the control groups and in the group treated with 12.5 J/cm(2) than in the group treated with 25 J/cm(2) . Conversely, VEGF immunomarking was more expressive in the group treated with 25 J/cm(2) than it was in the other two groups. Therefore, our findings suggest that the use of 25 J/cm(2) and 1 J of energy was more effective in stimulating the cellular processes involved in tissue repair on third-degree burns in rats by reducing the inflammatory phase, and stimulating angiogenesis, thus restoring the local microcirculation which is essential for cell migration.

Effects of low level laser therapy on inflammatory and angiogenic gene expression during the process of bone healing: A microarray analysis.

The process of bone healing as well as the expression of inflammatory and angiogenic genes after low level laser therapy (LLLT) were investigated in an experimental model of bone defects. Sixty Wistar rats were distributed into control group and laser group (830nm, 30mW, 2,8J, 94seg). Histopathological analysis showed that LLLT was able to modulate the inflammatory process in the area of the bone defect and also to produce an earlier deposition of granulation tissue and newly formed bone tissue. Microarray analysis demonstrated that LLLT produced an up-regulation of the genes related to the inflammatory process (MMD, PTGIR, PTGS2, Ptger2, IL1, 1IL6, IL8, IL18) and the angiogenic genes (FGF14, FGF2, ANGPT2, ANGPT4 and PDGFD) at 36h and 3days, followed by the decrease of the gene expression on day 7. Immunohistochemical analysis revealed that the subjects that were treated presented a higher expression of COX-2 at 36h after surgery and an increased VEGF expression on days 3 and 7 after surgery. Our findings indicate that LLLT was efficient on accelerating the development of newly formed bone probably by modulating the inflammatory and angiogenic gene expression as well as COX2 and VEGF immunoexpression during the initial phase of bone healing.

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

This study evaluated the morphological changes produced by LLLT on the initial stages of bone healing and also studied the pathways that stimulate the expression of genes related to bone cell proliferation and differentiation. One hundred Wistar rats were divided into control and treated groups. Noncritical size bone defects were surgically created at the upper third of the tibia. Laser irradiation (Ga-Al-As laser 830 nm, 30 mW, 94 s, 2.8 J) was performed for 1, 2, 3, 5, and 7 sessions. Histopathology revealed that treated animals produced increased amount of newly formed bone at the site of the injury. Moreover, microarray analysis evidenced that LLLT produced a significant increase in the expression TGF-ß, BMP, FGF, and RUNX-2 that could stimulate osteoblast proliferation and differentiation, which may be related to improving the deposition of newly formed bone at the site of the injury. Thus, it is possible to conclude that LLLT improves bone healing by producing a significant increase in the expression of osteogenic genes.

Porous bioactive scaffolds: characterization and biological performance in a model of tibial bone defect in rats.

The aim of this study was to evaluate the effects of highly porous Biosilicate(®) scaffolds on bone healing in a tibial bone defect model in rats by means of histological evaluation (histopathological and immunohistochemistry analysis) of the bone callus and the systemic inflammatory response (immunoenzymatic assay). Eighty Wistar rats (12 weeks-old, weighing±300 g) were randomly divided into 2 groups (n=10 per experimental group, per time point): control group and Biosilicate® group (BG). Each group was euthanized 3, 7, 14 and 21 days post-surgery. Histological findings revealed a similar inflammatory response in both experimental groups, 3 and 7 days post-surgery. During the experimental periods (3-21 days post-surgery), it was observed that the biomaterial degradation, mainly in the periphery region, provided the development of the newly formed bone into the scaffolds. Immunohistochemistry analysis demonstrated that the Biosilicate® scaffolds stimulated cyclooxygenase-2, vascular endothelial growth factor and runt-related transcription factor 2 expression. Furthermore, in the immunoenzymatic assay, BG presented no difference in the level of tumor necrosis factor alpha in all experimental periods. Still, BG showed a higher level of interleukin 4 after 14 days post-implantation and a lower level of interleukin 10 in 21 days post-surgery. Our results demonstrated that Biosilicate® scaffolds can contribute for bone formation through a suitable architecture and by stimulating the synthesis of markers related to the bone repair.

Evaluation of the bone healing process in an experimental tibial bone defect model in ovariectomized rats.

The aim of this study was to evaluate the influence of postmenopausal bone loss (induced by ovariectomy) in the process of bone healing in a tibial bone defect model in rats by means of histological evaluation of bone defects and the analysis of the expression of genes and proteins involved in bone consolidation. Twenty female Wistar rats (12 weeks old, weighing ±250 g) were randomly divided into two groups: control group (CG) and ovariectomized group (OG). Rats of OG were submitted to ovariectomy and after 8 weeks post-surgery, all animals were submitted to the tibial bone defect model. The main histological finding analysis revealed that ovariectomized animals showed a higher amount of granulation tissue and immature newly formed bone compared to CG. Furthermore, quantitative histological analysis showed that OG presented a significant decrease in the amount of newly formed bone (p = 0.0351). RT-PCR analysis showed no difference in Runx2, ALP, RANK, RANKL and Osterix gene expression 14-day post-surgery. Interestingly, immunohistochemical evaluation showed that Runx2 was down expressed (p = 0.0001) and RANKL was up expressed (p = 0.0022) in the OG. In conclusion, these data highlight that bone loss induced by ovariectomy causes an impairment in the capacity of bone to heal mainly probably because of alterations in the imbalance of osteoblasts and osteoclasts activities.