Evaluation of bone repair after application of a norbixin membrane scaffold with and without laser photobiomodulation (λ 780 nm)

Tailoring photobiomodulation to enhance tissue regeneration

Photobiomodulation (PBM), the use of biocompatible tissue-penetrating light to interact with intracellular chromophores to modulate the fates of cells and tissues, has emerged as a promising non-invasive approach to enhancing tissue regeneration. Unlike photodynamic or photothermal therapies that require the use of photothermal agents or photosensitizers, PBM treatment does not need external agents. With its non-harmful nature, PBM has demonstrated efficacy in enhancing molecular secretions and cellular functions relevant to tissue regeneration. The utilization of low-level light from various sources in PBM targets cytochrome c oxidase, leading to increased synthesis of adenosine triphosphate, induction of growth factor secretion, activation of signaling pathways, and promotion of direct or indirect gene expression. When integrated with stem cell populations, bioactive molecules or nanoparticles, or biomaterial scaffolds, PBM proves effective in significantly improving tissue regeneration. This review consolidates findings from in vitro, in vivo, and human clinical outcomes of both PBM alone and PBM-combined therapies in tissue regeneration applications. It encompasses the background of PBM invention, optimization of PBM parameters (such as wavelength, irradiation, and exposure time), and understanding of the mechanisms for PBM to enhance tissue regeneration. The comprehensive exploration concludes with insights into future directions and perspectives for the tissue regeneration applications of PBM.

Investigation of the optimal light parameters for photobiomodulation to induce osteogenic differentiation of the human bone marrow stem cell and human umbilical vein endothelial cell co-culture

Bones have an important role in the human body with their complex nature. Mesenchymal stem cells and endothelial cells together support their unique and complex nature. Photobiomodulation (PBM) is a promising method that provides cell proliferation, osteogenic differentiation, and bone regeneration. However, there are still unknowns in the mechanism of osteogenic differentiation induced by PBM. The main aim of the study is to understand the molecular mechanism of PBM at 655 and 808 nm of wavelengths and identify the most effective energy densities of both wavelengths for osteogenic differentiation. The effect of PBM on osteogenic differentiation of Human Bone Marrow Stem Cell (hBMSC) and Human Umbilical Vein Endothelial Cell (HUVEC) co-culture was examined at 1, 3, and 5 J/cm2 energy densities of red and near-infrared light through different analysis such as cell viability, scratch assay, intracellular reactive oxygen species production, and ATP synthesis, nitric oxide release, temperature monitoring, and osteogenic differentiation analyses. Even though all PBM-treated groups exhibited better results compared to the control group, 5 J/cm2 energy density induced faster cell proliferation and migration at both wavelengths. The increases in ATP and NO levels as signaling molecules, and the increases in DNA, ALPase, and calcium contents as osteogenic markers were higher in the groups treated with 5 J/cm2 energy density at both wavelengths. Only a slight change was obtained in the level of intracellular ROS after any light applications. It can be concluded that NO release has a very important role together with ATP production in PBM therapy to trigger DNA synthesis, ALPase activity, and mineralization for osteogenic differentiation of the hBMSC and HUVEC co-culture at 655 and 808 nm of wavelengths.

Evaluation of How Methacrylate Gelatin Hydrogel Loaded with Ximenia americana L. Extract (Steam Bark) Effects Bone Repair Activity Using Rats as Models

The use of bioactive materials, such as Ximenia americana L., to stimulate the bone repair process has already been studied; however, the synergistic effects of its association with light emitting diode (LED) have not been reported. The present work aims to evaluate the effect of its stem bark extract incorporated into methacrylate gelatin hydrogel (GelMA) on the bone repair process using pure hydrogel and hydrogel associated with LED therapy. For this purpose, the GelMA hydrogel loaded with Ximenia americana L. extract (steam bark) was produced, characterized and applied in animal experiments. The tests were performed using 50 male Wistar rats (divided into 5 groups) submitted to an induced tibia diaphyseal fracture. The therapy effects were verified for a period of 15 and 30 days of treatment using histological analysis and Raman spectroscopy. After 15 days of induced lesion/treatment, the new bone formation was significantly higher in the GXG (GelMA + X. americana L.) group compared to the control group (p < 0.0001). After 30 days, a statistically significant difference was observed when comparing the GXLEDG (GelMA + X. americana L. + LED) and the control group (p < 0.0001), the GXG and the control group (p < 0.001), and when comparing the GG, GXG (p < 0.005) and GXLEDG (p < 0.001) groups. The results shows that the Ximenia americana L. stem extract incorporated into GelMA hydrogel associated with LED therapy is a potentiator for animal bone repair.

Photobiomodulation therapy at red and near-infrared wavelengths for osteogenic differentiation in the scaffold-free microtissues

One of the novel strategies for bone tissue regeneration is photobiomodulation (PBM) which depends on the red and near-infrared light absorption by mitochondria and may trigger bone tissue regeneration via the production of intracellular ROS and ATP, NO release, etc. It is also important to identify the changes in those signal molecule levels in an in vivo mimicking platform such as 3-Dimensional (3D) Scaffold Free Microtissues (SFMs) that may serve more natural osteogenic differentiation responses to PBM. Herein, we aimed to increase the osteogenic differentiation capability of the co-culture of Human Bone Marrow Stem Cells (hBMSC) and Human Umbilical Vein Endothelial Cells (HUVECs) on 3D SFMs by triple light treatment at 655 and 808-nm of wavelengths with the energy densities of 1, 3, and 5 J/cm². We performed the analysis of cell viability, diameter measurements of SFMs, intracellular ROS production, NO release, ATP activity, temperature measurements, DNA content, ALPase activity, calcium content, and relative gene expressions of ALP, Collagen, and Osteopontin by qRT-PCR. It was found that both wavelengths were effective in terms of the viability of SFMs. 1 and 5 J/cm² energy densities of both wavelengths increased the SFM diameter with significant changes in intracellular ROS, ATP, and NO levels compared to the control group. We concluded that PBM therapy was successful to induce osteogenesis. 1 J/cm² at 655 nm of wavelength and 5 J/cm² at 808 nm of wavelength were the most effective energy densities for osteogenic differentiation on SFMs with triple light treatment.

Nanohydroxyapatite/Titanate Nanotube Composites for Bone Tissue Regeneration

Strategies for the production of new nanocomposites that promote bone tissue regeneration are important, particularly those that enhance the osteoinduction of hydroxyapatite in situ. Here, we studied and report the synthesis of nanohydroxyapatite and titanate nanotube (nHAp/TiNT) composites formulated at different concentrations (1, 2, 3, and 10 wt % TiNT) by means of a wet aqueous chemical reaction. The addition of TiNT affects the morphology of the nanocomposites, decreasing the average crystallite size from 54 nm (nHAp) to 34 nm (nHAp/TiNT10%), while confirming its interaction with the nanocomposite. The crystallinity index (CI) calculated by Raman spectroscopy and XRD showed that the values decreased according to the increase in TiNT concentration, which confirmed their addition to the structure of the nanocomposite. SEM images showed the presence of TiNTs in the nanocomposite. We further verified the potential cytotoxicity of murine fibroblast cell line L929, revealing that there was no remarkable cell death at any of the concentrations tested. In vivo regenerative activity was performed using oophorectomized animal (rat) models organized into seven groups containing five animals each over two experimental periods (15 and 30 days), with bone regeneration occurring in all groups tested within 30 days; however, the nHAp/TiNT10% group showed statistically greater tissue repair, compared to the untreated control group. Thus, the results of this study demonstrate that the presently formulated nHAp/TiNT nanocomposites are promising for numerous improved bone tissue regeneration applications.

In vivo evaluation of bone repair guided with biological membrane based on polyhydroxybutyrate and norbixin

The present work aimed to synthesize and verify the effectiveness of the polyhydroxybutyrate and norbixin membrane as a scaffold in bone defects induced in the tibia of rats. Twenty-four male Rattus norvegicus rats were used, divided into control and membrane groups. After anesthesia, a bone defect was induced in the right tibia, followed by the implantation of the biomaterial at the site of the lesion only in the membrane group, with euthanasia after 15 and 30 days of the experiment. The deposition of organic and inorganic matrix, the quality of newly formed bone tissue and the morphology of the bone defect were measured. After 15 days of the experiment, the biomaterial significantly influenced the deposition of hydroxyapatite crystals, the formation of collagen I matrix and mineralization content in relation to the control group, in addition to the abbreviation of the inflammatory process and superior quality of the newly formed bone tissue. After 30 days, only the membrane group had fully completed its repair process. The biomaterial acted as a scaffold in the regeneration of the guided bone defect by accelerating the synthesis of collagen matrix, mineralization content, density, and maturity when compared to the control group.

Effect of Cerium-Containing Hydroxyapatite in Bone Repair in Female Rats with Osteoporosis Induced by Ovariectomy

Osteoporosis is a public health problem, with bone loss being the main consequence. Hydroxyapatite (HA) has been largely used as a bioceramic to stimulate bone growth. In our work, a cerium-containing HA (Ce-HA) has been proposed and its effects on the antimicrobial and bone-inducing properties were investigated. The synthesis of the materials occurred by the suspension–precipitation method (SPM). The XRD (X-ray Diffraction) confirmed the crystalline phase, and the Rietveld refinement confirmed the crystallization of HA and Ce-HA in a hexagonal crystal structure in agreement with ICSD n° 26205. Characterizations by FT-IR (Fourier Transform Infrared Spectroscopy), XPS (X-ray Photoemission Spectroscopy), and FESEM-EDS (Field Emission Scanning Electron Microscope-Energy Dispersive X-ray Spectroscopy) confirmed the presence of cerium (Ce3+ and Ce4+). The antibacterial activity of Has was evaluated against Staphylococcus aureus 25,923 and Escherichia coli 25,922 strains, which revealed that the material has antimicrobial properties and the cytotoxicity assay indicated that Ce-containing HA was classified as non-toxic. The effects of Ce-HA on bone repair, after application in bone defects in the tibia of female rats with osteoporosis induced by ovariectomy (OVX), were evaluated. After 15 and 30 days of implantation, the samples were analyzed by Raman, histology and X-ray microtomography. The results showed that the animals that had the induced bone defects filled with the Ce-HA materials had more expressive bone neoformation than the control group.

Effects of photobiomodulation on bone defects grafted with bone substitutes: A systematic review of in vivo animal studies

A present, photobiomodulation therapy (PBMT) effectiveness in enhancing bone regeneration in bone defects grafted with or without biomaterials is unclear. This systematic review (PROSPERO, ref. CRD 42019148959) aimed to critically appraise animal in vivo published data and present the efficacy of PBMT and its potential synergistic effects on grafted bone defects. MEDLINE, CCCT, Scopus, Science Direct, Google Scholar, EMBASE, EBSCO were searched, utilizing the following keywords: bone repair; low-level laser therapy; LLLT; light emitting diode; LEDs; photobiomodulation therapy; in vivo animal studies, bone substitutes, to identify studies between 1994 and 2019. After applying the eligibility criteria, 38 papers included where the results reported according to "PRISMA." The results revealed insufficient and incomplete PBM parameters, however, the outcomes with or without biomaterials have positive effects on bone healing. In conclusion, in vivo animal studies with a standardized protocol to elucidate the effects of PBMT on biomaterials are required initially prior to clinical studies.

Characterization and assessment of the genotoxicity and biocompatibility of poly (hydroxybutyrate) and norbixin membranes

Purpose

To synthesize and characterize poly(hydroxybutyrate) (PHB) and norbixin membranes to evaluate them for genotoxicity in rats and wound healing in mice by histological staining.

Methods

For the evaluation of genotoxicity, male rats ( Rattus novegicus ) were divided into three groups (n= 5): 5% PHB/Norbixin membrane introduced into the peritoneum by laparotomy; B – negative control; C – positive control (intraperitoneal dose of cyclophosphamide 50 mg/kg). For the evaluation of biocompatibilty, a cutaneous wound was induced on the back of males mice ( Mus musculus ) divided into two experimental treatment groups: control and membrane that underwent euthanasia after 7 and 14 days treatment. Statistical analysis ware made by One Way Anova post hoc Tukey Test (p<0.05).

Results

Regarding the incidence of polychromatic erythrocytes, there was no difference between negative control and 5% PHB/Norbixin membrane; however, when compared to the positive control represented by cyclophosphamide, there was a significant difference (p <0.001). As for DNA damage, the changes induced in the first 4h were repaired in 24h. In addition, the membrane was effective in abbreviating the inflammatory process and served as a scaffold due to the stimulus to reepithelialization mainly on the 7 days of treatment.

Conclusion

The non-genotoxic PHB/Norbixin 5% membrane presented promising results that suggest its effectiveness as a guide for tissue regeneration given its biocompatibility.

Effect of low intensity photobiomodulation associated with norbixin-based poly (hydroxybutyrate) membrane on post-tenotomy tendon repair. In vivo study

Purpose:

To evaluate the in vivo response of photobiomodulation therapy associated with norbixin-based poly(hydroxybutyrate) membrane (PHB) in tenotomized calcaneal tendon.

Methods:

Thirty rats were randomly allocated to six groups (n=5 each): LED groups (L1, L2 and L3) and membrane + LED groups (ML1, ML2 and ML3). The right calcaneal tendons of all animals were sectioned transversely and were irradiated with LED daily, one hour after surgery every 24 hours, until the day of euthanasia. At the end of the experiments the tendons were removed for histological analysis.

Results:

The histological analysis showed a significant reduction in inflammatory cells in the ML1, ML2 and ML3 groups (p=0.0056, p=0.0018 and p<0.0001, respectively) compared to those in the LED group. There was greater proliferation of fibroblasts in the ML1 (p<0.0001) and L3 (p<0.0001) groups. A higher concentration of type I collagen was also observed in the ML1 group (p=0.0043) replacing type III collagen.

Conclusion:

Photobiomodulation in association with norbixin-based PHB membrane led to control of the inflammatory process. However, it did not favor fibroblast proliferation and did not optimize type I collagen formation in the expected stage of the repair process.

Effect of norbixin-based poly(hydroxybutyrate) membranes on the tendon repair process after tenotomy in rats

Purpose:

To determine the efficacy of norbixin-based poly(hydroxybutyrate) (PHB) membranes for Achilles tendon repair.

Methods:

Thirty rats were submitted to total tenotomy surgery of the right Achilles tendon and divided into two groups (control and membrane; n = 15 each), which were further subdivided into three subgroups (days 7, 14, and 21; n = 5 each). Samples were analyzed histologically.

Results:

Histological analysis showed a significant reduction in inflammatory infiltrates on days 7, 14 (p < 0.0001 for both), and 21 (p = 0.0004) in the membrane group compared to that in the control group. There was also a significant decrease in the number of fibroblasts in the control group on days 7, 14 (p < 0.0001), and 21 (p = 0.0032). Further, an increase in type I collagen deposition was observed in the membrane group compared to that in the control group on days 7 (p = 0.0133) and 14 (p = 0.0107).

Conclusion:

Treatment with norbixin-based PHB membranes reduces the inflammatory response, increases fibroblast proliferation, and improves collagen production in the tendon repair region, especially between days 7 and 14.

Effects of the combination of low-level laser therapy and anionic polymer membranes on bone repair

In view of the limitations of bone reconstruction surgeries using autologous grafts as a gold standard, tissue engineering is emerging as an alternative, which permits the fabrication and improvement of scaffolds to stimulate osteogenesis and angiogenesis, processes that are essential for bone repair. Polymers are used to mimic the extracellular bone matrix and support cell growth. In addition, bone neoformation can be induced by external factors such as laser irradiation, which stimulates bone metabolism. The objective of this study was to evaluate the regeneration of bone defects using collagen and elastin membranes derived from intestinal serosa and bovine auricular cartilage combined with low-level laser application. Thirty-six Wistar rats were operated to create a 3-mm defect in the distal metaphysis of the left femur and divided into six groups: G1 (control, no treatment); G2 (laser); G3 (elastin graft), G4 (elastin+laser); G5 (collagen graft); G6 (collagen+laser). The animals were sacrificed 6 weeks after surgery and the femurs were removed for analysis of bone repair. Macroscopic and radiological results showed the absence of an infectious process in the surgical area. This was confirmed by histological analysis, which revealed no inflammatory infiltrate. Histomorphometry showed that the formation of new bone started from the margins of the bone defect and its volume was greater in elastin+laser and collagen+laser. We conclude that newly formed bone in the graft area was higher in the groups that received the biomaterials and laser. The collagen and elastin matrices showed biocompatibility.