Improve Bone Repair Research Articles

Effect of Energy Level of Photobiomodulation Therapy on Bone Repair in Rats

The aim of this experimental study was to determine the effect of photobiomodulation therapy on bone repair in a rat tibia osteotomy model at 15 and 30 days. The sample consisted of 36 male Holtzman rats that were randomized into 6 equal groups. Groups A1 and A2: osteotomy + 1 J laser energy. Groups B1 and B2: osteotomy + 3 J laser energy. Groups C1 and C2 (controls): osteotomy only. The bone repair was analyzed by histological evaluation of osteoblasts and osteocytes both at 15 days (groups A1, B1, and C1) and at 30 days (groups A2, B2, and C2). Within the results, in all groups a greater number of osteoblasts was found at 15 days vs 30 days (p<0.05), and a greater number of osteocytes in B1 and C2 vs B2 and C1, respectively (p<0.05). When evaluating the 3 groups worked up to 15 days, more osteoblasts were found in A1 and C1 vs B1 (p<0.001); and osteocytes predominated in A1 and B1 vs C1 (p<0.001). At 30 days there was a greater quantity of osteoblasts in C2 vs A2 and B2 (p<0.05) and of osteocytes in C2 vs B2 (p<0.05). It is concluded that 1 J photobiomodulation therapy improved bone repair at 15 days; however, this improvement was not observed at 30 days because there were no differences between the irradiated groups and the control.

Low-level laser efficiency in reparation of bone defects

Introduction/Objective. Bone resorption is a common problem in dentistry, and bone reparation cannot be easily achieved. Several techniques of bone grafting and the use of low-level laser treatment (LLLT) as a new therapeutic optional recommended for improving bone repair were applied. The aim of the study was to investigate the influence of LLLT in bone repair of artificially made bone defects in the rat mandible using histomorphometry. Methods. The research was carried out on 60 female rats. Bone defects were made in the mandible, and animals were divided into two groups, each containing 30 animals. In the study group, the implantation site was submitted to GaAlAs laser irradiation 670 nm, 5 mW, 4 minutes per day for 5 days. The control group had no postoperative treatment. The animals were sacrificed after two, six, and eight weeks post LLLT, and preparations were analysed by histomorphometry, determining bone area fraction, bone area, integral density, mean density, and density variation. Results. Histomorphometric analysis revealed statistically higher values of area fraction, area, and integral density in the study group after two and six weeks. However, no beneficial laser effect was noticed after eight weeks. Conclusion. Low-level lasers have a stimulating effect on reparatory mechanisms in the early regeneration stage of artificially made bone defects in the rat mandible and can be used as a useful helping method in bone treatment.

Establishing a Diaphyseal Femur Fracture Model in Mice.

Bones have a significant regenerative capacity. However, fracture healing is a complex process, and depending on the severity of the lesions and the age and overall health status of the patient, failures can occur, leading to delayed union or nonunion. Due to the increasing number of fractures resulting from high-energy trauma and aging, the development of innovative therapeutic strategies to improve bone repair based on the combination of skeletal/mesenchymal stem/stromal cells and biomimetic biomaterials is urgently needed. To this end, the use of reliable animal models is fundamental to better understanding the key cellular and molecular mechanisms that determine the healing outcomes. Of all the models, the mouse is the preferred research model because it offers a wide variety of transgenic strains and reagents for experimental analysis. However, the establishment of fractures in mice may be technically challenging due to their small size. Therefore, this article aims to demonstrate the procedures for the surgical establishment of a diaphyseal femur fracture in mice, which is stabilized with an intramedullary wire and resembles the most common bone repair process, through cartilaginous callus formation.

Idiopathic Bone Cavity of Mandibular Symphysis: a Case Report

Introduction:An idiopathic bone cavity of the jaw is a rare pseudocyst with unclear etiology and is most commonly found in the body of the mandible. This lesion is generally asymptomatic and incidentally discovered on dental radiographs. Objetives:The aim of this study is to report the case of a 15-year-old male with surgical treatment of this lesion involving the mandibular symphysis, but the vitality pulp was positive. Conclusion: Although there is a non-surgical or surgical option for the treatment of this lesion, the latter is most indicated due to the possibility of a definitive diagnosis and improving bone repair.

FTY720 administration results in a M2 associated immunoregulatory effect that positively influences the outcome of alveolar bone repair outcome in mice.

The alveolar bone repair process may be influenced by multiple local and systemic factors, which include immune system cells and mediators. Macrophages allegedly play important roles in the repair process, and the transition of an initial inflammatory M1 profile into a pro-reparative M2 profile theoretically contributes to a favorable repair outcome. In this context, considering immunoregulatory molecules as potential targets for improving bone repair, this study evaluated the role of the immunoregulatory molecule FTY720, previously described to favor the development of the M2 phenotype, in the process of alveolar bone healing in C57Bl/6 (WT) mice. Experimental groups submitted to tooth extraction and maintained under control conditions or treated with FTY720 were evaluated by microtomographic (μCT), histomorphometric, immunohistochemical and molecular analysis to characterize healing and host response features at 0, 1, 3, 7 and 14days. Our results demonstrated that the FTY720 group presented higher bone tissue density, higher bone tissue volume, greater tissue volume fraction, greater number and thickness of trabeculae and a higher number of osteoblasts and osteoclasts than the control group. Accordingly, the bone markers BMP2, BMP7, ALPL, SOST and RANK mRNA expressions increased in the FTY720 treated group. Furthermore, the levels of FIZZ, ARG2 and IL-10 mRNA increased in the FTY720 group together with the presence of CD206+ cells, suggesting that the boost of bone formation mediated by FTY720 involves an increased polarization and activity of M2 macrophages in healing sites. Thus, our results demonstrate that FTY720 favored the process of alveolar bone repair, probably trough a strengthened M2 response, associated with an increased expression of markers osteogenic differentiation and activity markers. Immunoregulatory strategies based in the modulation of macrophage polarization profile can comprise effective tools to improve the bone repair process.

Novel bioactive collagen-polyurethane-pectin scaffolds for potential application in bone regenerative medicine

Recently, the development of bioactive scaffolds that allow improved bone repair is of interest for hard tissue regenerative medicine strategies. The use of biopolymers with synthetic polymer represents an innovative alternative for this purpose due to its excellent capacity to mimic the bone extracellular matrix. In this work, scaffolds based on bovine tendon collagen and pectin derived from orange (Citrus sinensis) peels were designed. The surfaces were prepared by a polymeric semi-interpenetration process where linear pectin chains were interpenetrated in a polyurethane-crosslinked collagen matrix. The effect of pectin content (10–40 wt.%) on the structural, physicochemical and biological properties of this type of scaffolds was evaluated. The increment in pectin content generates amorphous, granular surfaces with interconnected porosity, improving crosslinking, decreasing swelling and accelerating its rate of degradation in physiological and proteolytic media, also promoting antibacterial capacity showing inhibition of growth of pathogens such as E. coli. Specifically, the scaffold with 20 wt.% pectin (CPc20) shows a mechanical improvement of 342 ± 12% (with respect to crosslinked collagen), allowing the mineralization of 15 ± 1.5% of carbonated apatite on its surface, showing no cytotoxic effects on fibroblasts and allowing their proliferation; in addition, it was determined that immune system cells such as human monocytes can secrete high levels of transforming growth factor beta (TGF-β) and low levels of tumor necrosis factor alpha (TNF-α), conditions required in the process of bone formation. These results demonstrate that these bioactive scaffolds could be applied in bone tissue regenerative medicine strategies.

Acceleration Voltage and Spot Size of Advanced Bio Material in Nano scale

Hydrogels, films, micro/nanofibers, and particles, which have recently emerged as advanced biomaterials, have great potential for use as cell/drug carriers for localised drug delivery and as biomimetic scaffolds for future regenerative therapies. Biological properties such as biocompatibility, biodegradability, immunogenicity of biomaterials, and current application strategies are discussed. Finally, the final remarks and prospects for such advanced biomaterials are discussed. This article discusses stem cell biology, biomaterials, and technological approaches, as well as the design of biomaterials and devices used in vivo and in vitro. Generating new functional liver substitutes, improving bone repair processes, neurogenesis, groundbreaking models of cardiac fibrosis, and developing novel venous valve prostheses are some of the specific topics covered. This interdisciplinary approach emphasises how various properties of biomaterials and devices play a role in promoting Nano materials to Modern Technology.

Therapeutic approaches to activate the canonical Wnt pathway for bone regeneration.

Activation of the canonical Wingless-related integration site (Wnt) pathway has been shown to increase bone formation and therefore has therapeutic potential for use in orthopedic conditions. However, attempts at developing an effective strategy to achieve Wnt activation has been met with several challenges. The inherent hydrophobicity of Wnt ligands makes isolating and purifying the protein difficult. To circumvent these challenges, many have sought to target extracellular inhibitors of the Wnt pathway, such as Wnt signaling pathway inhibitors Sclerostin and Dickkopf-1, or to use small molecules, ions and proteins to increase target Wnt genes. Here, we review systemic and localized bioactive approaches to enhance bone formation or improve bone repair through antibody-based therapeutics, synthetic Wnt surrogates and scaffold doping to target canonical Wnt. We conclude with a brief review of emerging technologies, such as mRNA therapy and Clustered Regularly Interspaced Short Palindromic Repeats technology, which serve as promising approaches for future clinical translation.

Bioprinting Bone and Encoding Genes May Improve Bone Repair

Bioprinting Bone and Encoding Genes May Improve Bone Repair

Defective bone repletion in aged Balb/cBy mice was caused by impaired osteoblastic differentiation.

This study was undertaken to gain mechanistic information about bone repair using the bone repletion model in aged Balb/cBy mice. onemonth-old (young) mice were fed a calcium-deficient diet for 2weeks and 8month-old (adult) and 21-25month-old (aged) female mice for 4weeks during depletion, which was followed by feeding a calcium-sufficient diet for 16days during repletion. To determine if prolonged repletion would improve bone repair, an additional group of aged mice were repleted for 4 additional weeks. Control mice were fed calcium-sufficient diet throughout. In vivo bone repletion response was assessed by bone mineral density gain and histomorphometry. In vitro response was monitored by osteoblastic proliferation, differentiation, and senescence. There was no significant bone repletion in aged mice even with an extended repletion period, indicating an impaired bone repletion. This was not due to an increase in bone cell senescence or reduction in osteoblast proliferation, but to dysfunctional osteoblastic differentiation in aged bone cells. Osteoblasts of aged mice had elevated levels of cytosolic and ER calcium, which were associated with increased Cav1.2 and CaSR (extracellular calcium channels) expression but reduced expression of Orai1 and Stim1, key components of Stored Operated Ca2+ Entry (SOCE). Activation of Cav1.2 and CaSR leads to increased osteoblastic proliferation, but activation of SOCE is associated with osteoblastic differentiation. The bone repletion mechanism in aged Balb/cBy mice is defective that is caused by an impaired osteoblast differentiation through reducedactivationof SOCE.

Coordination of Osteoblastogenesis and Osteoclastogenesis by the Bone Marrow Mesenchymal Stem Cell-Derived Extracellular Matrix To Promote Bone Regeneration.

Extracellular matrix (ECM)-based therapies have been developed to improve bone repair because of their abundance of bioactive components. Besides the osteogenic promotion and the immune response, the potential effect of the ECM on the coordination between osteoblastogenesis and osteoclastogenesis in vivo should also deserve great attention because both osteoblasts and osteoclasts get involved in bone regeneration and are critical for the final repair outcome. Herein, based on our previous study on decellularization, antigen removal, and growth factor retention, porous poly (lactic-co-glycolic acid) (PLGA) scaffolds decorated with the bone marrow mesenchymal stem cell (BMSC)-derived ECM were prepared, and the functions of the ECM on BMSC osteogenic differentiation and osteoclastogenesis in vitro were preferentially investigated. Afterward, bone regeneration and osteoclast formation in vivo induced by ECM-decorated PLGA scaffolds were further studied. The in vitro tests revealed that ECM-decorated PLGA scaffolds obviously facilitated BMSC proliferation and osteogenic differentiation. However, when osteoclast precursors were cultured on the BMSC-derived ECM, the number and size of osteoclasts, expression of cathepsin K and matrix metalloproteinase 9, and tartrate-resistant acid phosphatase activity were notably decreased, accompanied by the reduction in the reactive oxygen species (ROS) level. Interestingly, the addition of exogenous hydrogen peroxide elevated the osteoclast amount on the ECM and up-regulated the resorption-related enzyme levels, implying that the repressive effect of the BMSC-derived ECM on osteoclasts may be related to the intracellular ROS. After implantation into calvarial defects, the ECM-decorated PLGA scaffolds significantly increased bone volume and bone mineral density compared with bare PLGA scaffolds and did not stimulate the overmuch formation of osteoclasts in vivo. This study evidenced that the BMSC-derived ECM may coordinate osteoblastogenesis and osteoclastogenesis and promote favorable bone formation without stimulating bone resorption.

Expression of inflammatory cytokines in mesenchymal stem cells derived from proximal humerus fractures.

Mesenchymal stem cells (MSCs) are an excellent treatment option for a wide variety of orthopaedic conditions. This study aimed to establish if bone marrow MSCs obtained from proximal humerus fractures can be an alternative source for obtaining primary cultures of human MSCs. Human bone marrow was obtained during osteosynthesis surgeries on closed proximal humerus fractures within 48 hours of injury. MSCs were harvested using the Ficoll gradient separation protocol and in vitro cultured until the third passage. Then, the cells were immunophenotyped by flow cytometry using stem cell specific surface markers. The cells were also induced to differentiate into osteoblasts and adipocytes for the characterization and confirmation of MSCs. The production of cytokines interleukin (IL)-1β, IL-6, IL-8, IL-10, tumor necrosis factor α (TNF-α), and interferon γ (IFN-γ) was assessed using enzyme-linked immunosorbent assay (ELISA) in the supernatant of the cultures after 3, 5 or 7 days. Immunophenotyping showed high expression of the stem cell surface markers CD73, CD90, and CD105 and negative or very low expression of CD34, CD45, CD11b, CD19, and human leukocyte antigen (HLA)-DR. The bone marrow derived MSCs were able to differentiate into osteoblasts and adipocytes. The quantification of secreted cytokines revealed that IL-8 was the most produced cytokine, followed by IL-6 and IL-10 at similar quantities and lower levels of IL-1β. TNF-α and IFN-γ were not detected. Proximal humerus fractures can be an alternative source for the collection of bone marrow MSCs. The cytokine production of these cells is very similar to the production profile of fracture haematomas previously reported and may be used for improving bone repair.

Does the incorporation of strontium into calcium phosphate improve bone repair? A meta-analysis

BackgroundThe application of calcium phosphate (CaP)-based bone substitutes plays an important role in periodontal regeneration, implant dentistry and alveolar bone reconstruction. The incorporation of strontium (Sr) into CaP-based bone substitutes appears to improve their biological properties, but the reported in vivo bone repair performance is inconsistent among studies. Herein, we conducted a systematic review and meta-analysis to investigate the in vivo performance of Sr-doped materials.MethodsWe searched PubMed, EMBASE (via OVIDSP), and reference lists to identify relevant animal studies. The search, study selection, and data extraction were performed independently by two investigators. Meta-analyses and sub-group analyses were conducted using Revman version 5.4.1. The heterogeneity between studies were assessed by I2. Publication bias was investigated through a funnel plot.ResultsThirty-five studies were finally enrolled, of which 16 articles that reported on new bone formation (NBF) were included in the meta-analysis, covering 31 comparisons and 445 defects. The overall effect for NBF was 2.25 (95% CI 1.61–2.90, p < 0.00001, I2 = 80%). Eight comparisons from 6 studies reported the outcomes of bone volume/tissue volume (BV/TV), with an overall effect of 1.42 (95% CI 0.65–2.18, p = 0.0003, I2 = 75%). Fourteen comparisons reported on the material remaining (RM), with the overall effect being -2.26 (95% CI − 4.02 to − 0.50, p = 0.0009, I2 = 86%).ConclusionsOur study revealed that Sr-doped calcium phosphate bone substitutes improved in vivo performance of bone repair. However, more studies are also recommended to further verify this conclusion.

Bioperformance Studies of Biphasic Calcium Phosphate Scaffolds Extracted from Fish Bones Impregnated with Free Curcumin and Complexed with β-Cyclodextrin in Bone Regeneration.

Fish bones are a natural calcium phosphate (CaP) sources used in biomaterials production for bone regeneration. CaP scaffolds can be enriched with other substances with biological activity to improve bone repair. This study aimed to evaluate the physicochemical properties and bone regeneration potential of biphasic calcium phosphate (BCP) scaffolds impregnated with free curcumin (BCP-CL) or complexed with β-cyclodextrin (BCP-CD) compared to BCP scaffolds. Rietveld’s refinement showed that BCP is composed of 57.2% of HAp and 42.8% of β-TCP and the molar ratio of Ca/P corresponds to 1.59. The scaffolds presented porosity (macro and microporosity) of 57.21%. Apatite formation occurred on the BCP, BCP-CL, and BCP-CD surface, in vitro, in SBF. Micro-Raman technique showed a reduction in the dissolution rate of β-TCP in the curcumin-impregnated scaffolds over time, and in vivo studies on critical-size defects, in rat calvaria, had no additional regenerative effect of BCP-CL and BCP-CD scaffolds, compared to BCP scaffolds. Despite this, the study showed that curcumin impregnation in BCP scaffolds prolongs the release of the β-TCP phase, the BCP- phase with the higher osteoinductive potential, representing an advantage in tissue engineering.

Local Application of Mineral-Coated Microparticles Loaded With VEGF and BMP-2 Induces the Healing of Murine Atrophic Non-Unions.

Deficient angiogenesis and disturbed osteogenesis are key factors for the development of nonunions. Mineral-coated microparticles (MCM) represent a sophisticated carrier system for the delivery of vascular endothelial growth factor (VEGF) and bone morphogenetic protein (BMP)-2. In this study, we investigated whether a combination of VEGF- and BMP-2-loaded MCM (MCM + VB) with a ratio of 1:2 improves bone repair in non-unions. For this purpose, we applied MCM + VB or unloaded MCM in a murine non-union model and studied the process of bone healing by means of radiological, biomechanical, histomorphometric, immunohistochemical and Western blot techniques after 14 and 70 days. MCM-free non-unions served as controls. Bone defects treated with MCM + VB exhibited osseous bridging, an improved biomechanical stiffness, an increased bone volume within the callus including ongoing mineralization, increased vascularization, and a histologically larger total periosteal callus area consisting predominantly of osseous tissue when compared to defects of the other groups. Western blot analyses on day 14 revealed a higher expression of osteoprotegerin (OPG) and vice versa reduced expression of receptor activator of NF-κB ligand (RANKL) in bone defects treated with MCM + VB. On day 70, these defects exhibited an increased expression of erythropoietin (EPO), EPO-receptor and BMP-4. These findings indicate that the use of MCM for spatiotemporal controlled delivery of VEGF and BMP-2 shows great potential to improve bone healing in atrophic non-unions by promoting angiogenesis and osteogenesis as well as reducing early osteoclast activity.

Effect of sulfated chitosan hydrogel on vascularization and osteogenesis

Bone regeneration and vascularization have presented a clinical challenge for decades. Considering the importance of stem cells, such as mesenchymal stem cells (MSCs), in bone regeneration, endothelial progenitor cells (EPCs) are crucial during bone repair. This paper presented sulfated chitosan (SCS)-based hydrogel scaffolds to accelerate bone tissue regeneration, vascularization enhancement, and improve bone repair. Thus, these scaffolds played a crucial role in the regeneration of blood vessels, with the increased presentation of epithelial progenitors and immune cells in this microenvironment. In vivo experiments showed that the biological impact of SCS was critical for angiogenesis and vascularization, in conjunction with bone morphogenetic protein-2 (BMP-2) and MSCs. Therefore, the BMP-2-/hydrogel system established in this study promoted angiogenesis, stimulated MSC proliferation, and enhanced bone tissue formation. In addition, this paper highlighted the angiogenic role of SCS in creating a micro-environment for effective bone repair and provides insight into the future development of new bone regeneration material.

Preparation and Physicochemical Evaluation of Hydroxyapatite-gelatin Nanoparticles

One of the promising fields of research is tissue engineering that can facilitate available therapeutic methods. Nanosized hydroxyapatite (HA) is one of the key elements in mineral bone. It is possible to affect the surrounding osteoprogenitor cells using nano-sized HA and through this improve bone repair through changing paracrine signaling. The present paper is an attempt to prepare and evaluate physicochemical properties of hydroxyapatite-gelatin nanoparticles. To this end, two sizes were prepared including S100 and S150 using standard chemical precipitation. To characterize the size and morphology of the synthesized powders, X-ray diffraction and Brunauer-Emmett-Teller (BET) surface area were determined using Autosrob-IQ2-MP. To measure the calcium ions released by HANPs, an inductively coupled plasma optical emission spectrometer (ICP-OES) was used. The collected data was analyzed in SPSS 19.0. In the case of S100, the hydrodynamic diameter based on DLS analyses was equal to 626.10±14.95nm; this figure for S150 was equal to 262.33±46.5. There was a larger specific surface area in S100 compared to S150; in addition, S100 had wider diffraction peaks, which is in agreement with small and poorly crystalline crystals. On the other hand, the diffraction peaks of S150 were sharper, which means that the crystallinity was higher in S150. In addition, HANPs of all sizes had degradability and HANPs with smaller sizes (S100) degraded faster compared to larger-sized S150. The pH level of the control, S100, and S150 was 7.24±0.01, and 7.26±0.02 so that there was no significant difference between them. Nanoparticle size is a key factor in the biological environment, which provides a reference for HANPs in biomedical uses.

Apolipoprotein E impairs aged bone fracture healing

Bone fracture healing and osteoblast differentiation are impaired with advanced age. Using a combination of parabiosis and proteomic models, we identified apolipoprotein E (ApoE) to be an aging factor in bone regeneration. Circulating levels of ApoE increased with age in patients and in mice. ApoE impaired bone fracture healing by decreasing bone deposition in the fracture callus which subsequently decreased the mechanical strength of healed tissue. Osteoblasts serve as the sole bone forming cells within the body. In tissue culture models, ApoE treatment decreased osteoblast differentiation and activity which led to decreased matrix formation and mineralization. This inhibition of osteoblast differentiation relied on down-regulation of the Wnt/β-catenin pathway. In mouse models, aged bone repair was rejuvenated when we lowered circulating ApoE levels using a hepatotropic AAV-siRNA model – serving as a proof of concept that ApoE can be targeted to improve bone repair in an older population. While promising, knockdown of circulating ApoE in such a fashion is likely not translatable to patient care. Thus, current work in our laboratory is focused on developing treatment strategies that temporally decrease circulating ApoE levels and consequently improve bone healing after acute injury and/or surgical orthopedic procedure in the geriatric population.

Plasminogen Regulates Fracture Repair by Promoting the Functions of Periosteal Mesenchymal Progenitors.

Defective or insufficient bone repair and regeneration are common in patients as a result of major trauma or severe disease. Cell therapy with periosteal mesenchymal progenitors, which can be limited in severe injury, serves as a promising approach; however, its efficacy is limited due to a repair-hostile ischemic tissue microenvironment after traumatic fracture. Here we report that plasminogen (Plg), a factor that is upregulated in these environments, is critical for fracture healing. Plg knockout mice had impaired trabecular and cortical bone structure and exhibited delayed and incomplete fracture healing. Interestingly, Plg deficiency greatly reduced the thickness of expanded periosteum, suggesting a role of Plg in periosteal mesenchymal progenitor-mediated bone repair. In culture, Plg increased cell proliferation and migration in periosteal mesenchymal progenitors and inhibited cell death under ischemic conditions. Mechanistically, we revealed that Plg cleaved and activated Cyr61 to regulate periosteal progenitor function. Thus, our study uncovers a cellular mechanism underlying fracture healing, by which Plg activates Cyr61 to promote periosteal progenitor proliferation, survival, and migration and improves bone repair after fracture. Targeting Plg may offer a rational and effective therapeutic opportunity for improving fracture healing. © 2021 American Society for Bone and Mineral Research (ASBMR).

Front Cover: Biomaterials and nanomedicine for bone regeneration: Progress and future prospects (EXP2 2/2021)

In article 20210011, Claudia Corbo, Wei Tao, and co-workers present an overview of common causes of bone defects, the unmet clinical needs, and the utility of biomaterials and nanotechnology to facilitate bone regeneration. The authors propose several key approaches to improve bone repair strategies that guide the future research direction of bone repair to improve treatment.