Improve Bone Healing Research Articles

IGFBP7 regulates the osteogenic differentiation of bone marrow-derived mesenchymal stem cells via Wnt/β-catenin signaling pathway.

Insulin-like growth factor-binding protein 7 (IGFBP7), a low-affinity IGF binder, may play an important role in bone metabolism. However, its function in osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (BMSCs) remains unclear. Therefore, we investigated its effects on osteogenic differentiation. Overexpression of IGFBP7 enhanced the expression of osteo-specific genes and proteins, and IGFBP7 knockdown decreased osteogenesis-specific markers. More mineral deposits and higher alkaline phosphatase activity were observed after the up-regulation of IGFBP7. Moreover, β-catenin levels were up-regulated by the overexpression of IGFBP7 or the addition of extracellular IGFBP7 protein and were reduced by the depletion of IGFBP7. The increase in osteogenic differentiation due to the overexpression of IGFBP7 was partially decreased by specific Wnt/β-catenin signaling inhibitors. Using a rat tibial osteotomy model, a sheet of IGFBP7-overexpressing BMSCs improved bone healing, as demonstrated by imaging, biomechanical, and histologic analyses. Taken together, these findings indicate that IGFBP7 regulates the osteogenic differentiation of BMSCs partly via the Wnt/β-catenin signaling pathway.-Zhang, W., Chen, E., Chen, M., Ye, C., Qi, Y., Ding, Q., Li, H., Xue, D., Gao, X., Pan, Z. IGFBP7 regulates the osteogenic differentiation of bone marrow-derived mesenchymal stem cells via Wnt/β-catenin signaling pathway.

Effectiveness of Nanosilver, Nanogold and their Combination on the Healing Potential of Critical Radial Bone Defects in Rats

A new composition of platelet-fibrin glue (FPG), gelatin (Gel), nanohydroxyapatite (nHA), silver nanoparticles (SNPs) and gold nanoparticles (GNPs) was synthesized and employed in preparation of hybrid scaffolds and was applied in bone tissue engineering in the surgically critical-sized bone defect in a rat model. Sixty bilateral radial bone defects were randomly divided into six groups including untreated defects, autograft and those treated with Gel/FPG/nHA containing scaffolds including nHA alone, nHA/SNPs, nHA/GNPs and nHA/SNPs/GNPs (n=10 in each group). The defects were assessed by radiography, histopathology, scanning electron microscopy and biomechanical testing. In comparison with the untreated defects, all the treated defects demonstrated significantly superior new bone formation, remodeling and bone tissue volume. Moreover, the defects treated with GNPs showed significantly higher ultimate strength, yield strength and stiffness. The nHA and nHA/SNPs moderately improved bone regeneration that were not close to the autograft in some parameters, whereas nHA/GNPs and nHA/SNPs/ GNPs significantly improved bone healing closely comparable with those of the autograft group in most parameters. In conclusion, although all the scaffolds had some beneficial effectiveness on bone regeneration, the scaffolds containing GNPs were more effective in improving the structural and functional properties of the newly formed bone and were more osteoinductive than other scaffolds and were comparable to the autograft. Therefore, the scaffolds including GNPs can be regarded as a promising option to be used in bone tissue engineering.

Laser for bone healing after oral surgery: systematic review.

The purpose of this study is to perform a systematic review on the use of lasers in oral surgery for bone healing. Selection of articles was carried out by two evaluators in Pubmed and Web of Science databases for published articles and OpenGray for gray literature. Search strategy was developed based on the PICO Question "Does the use of lasers after oral surgery improve bone healing?". Eligibility criteria were: being on laser; evaluate bone healing; involve oral surgery; do not be about implant, periodontics, orthodontics, osteonecrosis or radiotherapy, nor revisions, clinical cases, etc. Data were collected from each article in a structured spreadsheet and a descriptive analysis was performed. Risk assessment of bias of the articles was carried out through the tool elaborated by the Cochrane collaboration. A total of 827 potentially relevant references were identified. No articles were found in OpenGray. Eleven articles met the eligibility criteria and were included in the systematic review. Most of studies were in vivo and in jaw, being conducted with low-power lasers which were applied immediately after the surgical procedure of extraction. Neoformation and bone density were the outcomes of choice and there was a tendency of increase in bone density, neoformation, regeneration, mineralization, or bone condensation when laser was applied. Regarding the bias risk assessment, studies were not clear in reporting most of the parameters. Low-power laser therapy seems to reduce time of bone healing in oral surgery, although there are no defined protocols and the level of evidence is still considered weak.

Baculovirus-Mediated miR-214 Knockdown Shifts Osteoporotic ASCs Differentiation and Improves Osteoporotic Bone Defects Repair

Osteoporotic patients often suffer from bone fracture but its healing is compromised due to impaired osteogenesis potential of bone marrow-derived mesenchymal stem cells (BMSCs). Here we aimed to exploit adipose-derived stem cells from ovariectomized rats (OVX-ASCs) for bone healing. We unraveled that OVX-ASCs highly expressed miR-214 and identified 2 miR-214 targets: CTNNB1 (β-catenin) and TAB2. We demonstrated that miR-214 targeting of these two genes blocked the Wnt pathway, led to preferable adipogenesis and hindered osteogenesis. As a result, OVX-ASCs implantation into OVX rats failed to heal critical-size metaphyseal bone defects. We further engineered the OVX-ASCs with a novel Cre/loxP-based hybrid baculovirus vector that conferred prolonged expression of miR-214 sponge. Gene delivery for miR-214 sponge expression successfully downregulated miR-214 levels, activated the Wnt pathway, upregulated osteogenic factors β-catenin/Runx2, downregulated adipogenic factors PPAR-γ and C/EBP-α, shifted the differentiation propensity towards osteogenic lineage, enhanced the osteogenesis of co-cultured OVX-BMSCs, elevated BMP7/osteoprotegerin secretion and hindered exosomal miR-214/osteopontin release. Consequently, implanting the miR-214 sponge-expressing OVX-ASCs tremendously improved bone healing in OVX rats. Co-expression of miR-214 sponge and BMP2 further synergized the OVX-ASCs-mediated bone regeneration in OVX rats. This study implicates the potential of suppressing miR-214 by baculovirus-mediated gene delivery in osteoporotic ASCs for regenerative medicine.

Healing potential of nanohydroxyapatite, gelatin, and fibrin-platelet glue combination as tissue engineered scaffolds in radial bone defects of rats

ABSTRACTDifferent biomaterials have been used in orthopedic surgery. Evaluation of biomaterials for bone healing promotion has been a wide area of research of the orthopedic field. Sixty critical size defects of 5 mm long were bilaterally created in the radial diaphysis of 30 rats. The animals were randomly divided into six equal groups as empty defect, autograft, nanohydroxyapatite (nHA), Gelatin (Gel)-nHA, fibrin-platelet glue (FPG)-nHA, and Gel-FPG-nHA groups (n = 10 in each group). Radiographs of each forelimb were taken postoperatively on the 1st day and then at the 28th and 56th days post injury. After 56 days, the rats were euthanized and their harvested healing bone samples were evaluated by histopathology, scanning electron microscopy, and biomechanical testing.All the treated defects demonstrated significantly superior new bone formation, remodeling, and bone tissue volume. Moreover, the defects treated with FPG-nHA showed significantly higher ultimate load, yield load, and stiffness. The Gel-FPG-nHA moderately improved bone regeneration that was not close to the autograft in some parameters, whereas FPG-nHA significantly improved bone healing closely comparable with the autograft group in most parameters. In conclusion, although all the nHA-containing scaffolds had some beneficial effects on bone regeneration, the FPG-nHA scaffold was more effective in improving the structural and functional properties of the newly formed bone and was more osteoinductive than the Gel and was comparable to the autograft. Therefore, the FPG can be regarded as a promising option to be used in conjunction with mineral scaffolds for bone tissue engineering.

Local and Systemic Morphofunctional Response of Osteoporotic Rabbits Bone Defect Following Implantation of Strontium Doped Biphasic Ceramic Granules

Variety of different bone substitutive materials are synthetized to improve bone healing potentials in pathological bone conditions. Physiologically active molecules within biomaterials, can initiate expression level of biomarkers, regulating bone remodeling. Aim of our study was to analyze bone healing process in bone defects followed by implantation with 5% strontium substituted hydroxyapatite (HAP) /tricalcium phosphate (TCP) 70/30 granules (group A) or HAP/TCP biphasic ceramic granules without strontium substitution (group B), or sham surgery affected bone (group C) in osteoporotic rabbits’ femur. Tissue samples from contralateral intact left leg were used for evaluation of systemic effects after surgery. Changes of bone volume were measured and appearance of OPG, NFkB-105, OC, COL-1, BMP-2/4, MMP-2, TIMP-2, IL-1 and IL-10-positive osteocytes in osteoporotic rabbits’ bone defect were evaluated. No statistical difference between groups of trabecular bone volume was detected. All analyzed markers showed higher appearance of positive osteocytes in groups A and B with comparison to control left leg (p<0.05). Only NFkB105-positive cells showed important difference between sham surgery affected leg and control one (p=0.034). Numerous OPG-positive cells appeared in group A, while moderate number of them was found in groups B and C (p=0.025; p=0.027). Numerous to abundant OC-positive osteocytes were detected in group A, while moderate in group C (p=0.034). Statistical difference of rest biomarkers between groups was not detected. We concluded that implantation of biomaterials in osteoporotic bone improves local bone regenerative properties. However, the notable increase of OPG-containing cells proves the increase of osteoclastogenesis suppression and gives the evidence for renew of bone functionality.

Peri-Implant Osteogenesis Behavior in Ovariectomized Rats Treated with Strontium Ranelate

The aim of this study was to evaluate the bone repair and biomechanical responss after installation of implants in tibia of ovariectomized rats treated with strontium ranelate (RE). 30 Wistar adult rats were divided into 3 groups (n = 10): Group OVX, rats submitted to bilateral ovariectomy; SHAM group, rats sham submitted surgery of ovariectomy; OVX group RE, rats submitted to ovariectomy and treated with RE. 30 days after ovariectomy, RE OVX rats were orally gavage 625 mg / kg / day of RE until euthanasia of the animals. 30 days after the start of medication (RE), each animal received 1 implant per tibia. Euthanasia was performed 42 days after implant placement. In a tibia held the reverse torque of the implants with digital torque wrench and the other tibia was removed in order to realize the demineralization pocess of peri-implant tissue for histological and immunohistochemical evaluation. The higher reverse torque values were found in RE OVX group and SHAM followed by OVX (p <0.05, ANOVA / Tukey). Immunostaining osteoprotegerin was more pronounced in ER OVX and sham groups when compared to the OVX group. While the RANKL protein proved more marking in OVX rats. For all microtomography parameters there was no statistically significance difference among the groups (P>0.05), however it was clear that RE showed a tendency to improve the quantity (BV/TV: SHAM=39.92%, OVX=37.8%, and OVX/RE 38.30%) and quality (Tb.Th and Tb.N) of bone tissue. Therefore, the RE was able to improve bone healing and biomechanics around the implants in ovariectomized rats.

Strontium Ranelate in the Healing of Fractures Complicated with Delayed Union. It is Really Effective?

Osteoporosis is a systemic skeletal disease characterized by low bone strength, which leads to an increased risk of fracture. The primary objective of osteoporosis treatment is the prevention of fragility fractures and the secondary objective is their rapid healing if they occur. Strontium ranelate is an antiosteoporotic therapeutic agent with a double action mechanism: the increase of bone formation and the decrease of bone resorption, contributing thus to the improvement of bone healing. Preclinical studies have demonstrated the efficacy of strontium ranelate for the improvement of bone healing and bone microarhitecture, as well as of the osteointegration of implants. Some clinical cases have been reported regarding the efficacy of strontium ranelate in the healing of long bone fractures complicated by nonunion or delayed union. In the present study we have reported 2 clinical cases that demonstrate the effectiveness of the treatment with strontium ranelate (Osseor) for 3-6 months in the healing of complicated long bone fractures with delayed union. Our cases confirm the results of the open label study CL3-12911-036 (delayed union and non-union fracture study), where the treatment with 2 g/day of strontium ranelate improved healing and led to a better quality of life. Even if there are some cardiovascular contraindications, strontium ranelate is proven to reduce vertebral and non-vertebral fracture risk in osteoporosis and in the same time improves bone microarchitecture and accelerates fracture healing.

Regulatory elements driving the expression of skeletal lineage reporters differ during bone development and adulthood

To improve bone healing or regeneration more insight in the fate and role of the different skeletal cell types is required. Mouse models for fate mapping and lineage tracing of skeletal cells, using stage-specific promoters, have advanced our understanding of bone development, a process that is largely recapitulated during bone repair. However, validation of these models is often only performed during development, whereas proof of the activity and specificity of the used promoters during the bone regenerative process is limited. Here, we show that the regulatory elements of the 6kb collagen type II promoter are not adequate to drive gene expression during bone repair. Similarly, the 2.3kb promoter of collagen type I lacks activity in adult mice, but the 3.2kb promoter is suitable. Furthermore, Cre-mediated fate mapping allows the visualization of progeny, but this label retention may hinder to distinguish these cells from ones with active expression of the marker at later time points. Together, our results show that the lineage-specific regulatory elements driving gene expression during bone development differ from those required later in life and during bone repair, and justify validation of lineage-specific cell tracing and gene silencing strategies during fracture healing and bone regenerative applications.

Improved autologous cortical bone harvest and viability with 2Flute otologic burs.

To determine if 2Flute (Stryker Corporation, Kalamazoo, MI) otologic burs improve the size, cellular content, and bone healing of autologous cortical bone grafts harvested during canal wall reconstruction (CWR) tympanomastoidectomy with mastoid obliteration. Institutional review board-approved prospective cohort study. Human autologous cortical bone chips were harvested using various burs (4 and 6 mm diameter; multiflute, and 2Flute [Stryker Corporation]) from patients undergoing CWR tympanomastoidectomy for the treatment of chronic otitis media with cholesteatoma. Bone chip size, cell counts, cellular gene expression, and new bone formation were quantified. Bone chips were significantly larger when harvested with 2Flute (Stryker Corporation) bur compared to multiflute burs at both 6 mm diameter (113 ± 14 μm2 vs. 66 ± 8 μm2 ; P < 0.05) and 4 mm diameter (70 ± 8 μm2 vs. 50 ± 3 μm2 ; P < 0.05). After 2 weeks in culture, cell numbers were significantly higher when harvested with 2Flute (Stryker Corporation) bur compared to multiflute burs at both 6 mm diameter (48.7 ± 3 vs. 31.8 ± 3 cells/μg bone; P < 0.05) and 4 mm diameter (27.6 ± 1.2 vs. 8.8 ± 1.2 cells/μg bone; P < 0.05). Bone-derived cells express osteoblast markers (alkaline phosphatase, osteocalcin). Cultured cells are able to form new bone in culture, and bone formation is facilitated by the presence of bone chips. Use of 2Flute (Stryker Corporation) otologic burs for human autologous cortical bone harvest results in more viable bone fragments, with larger bone chips and more osteoblasts. Future studies are needed to determine if this leads to improved bone healing. NA. Laryngoscope, 128:E41-E46, 2018.

Strontium- and cobalt-substituted bioactive glasses seeded with human umbilical cord perivascular cells to promote bone regeneration via enhanced osteogenic and angiogenic activities.

Bone regeneration is considered as an unmet clinical need. The most recent researches focused on incorporation of strontium (Sr2+) and cobalt (Co2+) ions into bioactive glasses structure. Strontium is an alkaline earth metal which is currently used in the treatment of osteoporosis. Also, cobalt is considered as another promising element in the bone regeneration field that may induce hypoxia-mediated angiogenesis. In this study, the osteogenic potential of the strontium- and cobalt-substituted bioactive glasses in granule form seeded with human umbilical cord perivascular cells (HUCPVCs) was evaluated in vitro and in vivo. Indeed, the main goal of this study was to improve the osteogenenic and angiogenic properties of bioactive glasses through the incorporation of strontium and cobalt ions in the glass composition. Although some researches have been conducted on this subject, the influence of the simultaneous use of strontium and cobalt ions on the improvement of bone healing in vivo has been not yet well understood and, therefore, deserves further investigation.

The effect of a hydroxyapatite impregnated PCL membrane in rat subcritical calvarial bone defects

ObjectiveThe present study evaluated the effect of polymeric-nanofibers membranes impregnated with microparticulate hydroxyapatite (HA) in the subcritical calvarial bone defects (SCBD) healing. DesignPCL membranes with and without HA were obtained by electrospinning. SCBD were perforated (3.3mm) in left and right sides of 36 rat calvarias. The right-side SBCD of 18 animals was filled with HA mixed with blood clot and blood clot at the contralateral side. The remaining animals received PCL+HA membrane at the right-side SCBD and PCL membrane at the contralateral side. Animals were killed after 30, 60 and 90days after surgery. Bone defect volume (in mm3) was measured by tomography (CBCT). Qualitative histological analysis and SBCD area (in mm2) were measured. Quantitative data were submitted to Kruskal-Wallis/Dunn tests. ResultsReduction of SBCD volume was observed in all treatments but PCL. Association with HA significantly improved bone healing induced by PCL and blood clot. PCL+HA induced the lowest SBCD volume at 60 and 90days. Complete bone healing was not observed even at 90days in SCBD treated with blood clot. In every period, more bone formation was observed for SCBD treated with membranes. ConclusionsWe concluded that both PCL membrane and HA were able to improve bone healing.

The Role of Platelet Rich Plasma on Healing of Induced Femoral Fracture Fixed With Dynamic Compression Plate in Dogs.

The present study was carried out to evaluate the platelet rich plasma (PRP) as a factor for accelerating bone healing and compared with normal healing in 18 apparently healthy male mongrel dogs based on clinical, radiographic and histopathological findings. Induction of femoral fracture was done in all dogs of both groups, a gap (0.5 cm × 0.5cm with the whole depth of the near cortex) was created at the fracture sit bone rongeur and the fracture was fixed with standard dynamic compression plate (DCP) and self taping cortical screws. Dogs were divided into two equal groups, each of 9 dogs. Group I was left as a control. In group II, the gap was packed with autogenous PRP. The results of this study pointed out that PRP slightly improved bone healing.

Effect of strontium citrate on bone consolidation during mandibular distraction osteogenesis.

Mandibular distraction osteogenesis (MDO) involves a lengthy consolidation phase where complications can occur. Strontium is an element that has been shown to improve bone healing. The objective of this study was to determine whether strontium citrate can be used to enhance bone healing during MDO in a rabbit model. Prospective animal model study. Custom-made MDO devices were placed on 20 New Zealand White rabbits. After a 7-day latency period, distraction was performed at 1 mm/day for 5 days. The study group rabbits (n = 10) received oral strontium citrate; the other 10 rabbits served as controls. Mandibles were removed at the end of the consolidation period (4 weeks). Formation and healing of new bone were evaluated with microcomputed tomography, histology, and a three-point bending mechanical test. New bone formed in all animals, but the consolidation process was enhanced in rabbits that received strontium. The histological analysis showed that study group rabbits had more mature bone. Microcomputed tomographic images demonstrated significantly higher bone density for study group animals, and the three-point bending test results demonstrated that the maximum load of the study group specimens was significantly greater than that of the control group mandibles. Strontium citrate improved the formation of new bone in the current rabbit model of MDO. The prolonged consolidation period may be shortened with strontium citrate, which may also have the potential to reduce complications. NA Laryngoscope, 127:E212-E218, 2017.

Pilot study on laser propagation in maxillary and mandibular bone: Grey level image analysis for optical measurements

BackgroundBone tissue anatomy, density and porosity vary among subjects in different phases of life and even within areas of a single specimen. The optical characteristics of changes in bone tissue are analyzed based on these properties. Photobiomodulation has been used to improve bone healing after surgery or fractures. Thus, knowledge on light propagation is of considerable importance to the obtainment of successful clinical outcomes. ObjectiveThis study determines light penetration and distribution in human maxillary and mandibular bones in three different regions (anterior, middle, and posterior). MethodsA HeNe laser (633nm) irradiated maxillary and mandibular bones in the cervical–apical direction. The light propagation and scattering pattern were acquired and the grey level of the images was analyzed. Three-dimensional plots of the intensity profile and attenuation profiles were created. ResultsDifferences in optical properties were found between the mandibular and maxillary bones. The maxilla attenuated more light than the mandible at all sites, leading to a shallower penetration depth. ConclusionOur results provide initial information on the behavior of the propagation of red laser on alveolar bone using an optical method.

Comparative study on the healing potential of chitosan, polymethylmethacrylate, and demineralized bone matrix in radial bone defects of rat

This study aimed to compare the effectiveness of xenogeneic demineralized bone matrix (DBM), chitosan (CS), and polymethylmethacrylate (PMMA) on the regeneration of the critical-sized radial bone defects in rats after eight weeks. Fifty bilateral radial bone defects were randomly divided into five groups including untreated defects and those treated with autograft, CS scaffold, PMMA, and DBM. The defects were evaluated by diagnostic imaging, histopathology, histomorphometry, scanning electron microscopy, and biomechanical testing. Compared with the defect, CS, and PMMA groups, the autograft and DBM treated defects showed significantly higher new bone formation, bone volume, ultimate mechanical strength, and stiffness, but significantly lower inflammatory cells, fibroblasts, fibrocytes, and strain. Moreover, DBM showed significantly superior biocompatibility, biodegradability, osteoconductivity, and osteoinductivity to the CS scaffold and PMMA. In conclusion, both CS and PMMA alone were non-biocompatible polymers with slow biodegradation which retarded bone regeneration, whereas DBM significantly improved bone healing close to the gold method. However CS was not osteoconductive or osteoinductive alone, it can be combined with other biomaterials and molecules considering the excellent properties of this carbohydrate biopolymer for bone healing and regeneration.

Efficacy and safety of human mesenchymal stromal cells in healing of critical-size bone defects in immunodeficient rats.

To evaluate the preclinical efficacy and safety of human mesenchymal stem cells (hMSC) rapidly expanded in growth medium for clinical use with human serum and recombinant growth factors, we conducted a controlled, randomized trial of plasma clots with hMSC vs. plasma clots only in critical segmental femoral defects in rnu/rnu immunodeficient rats. X-ray, microCT and histomorphometrical evaluation were performed at 8 and 16 weeks. MSC were obtained from healthy volunteers and patients with lymphoid malignancy. Human MSC survived in the defect for the entire duration of the trial. MSC from healthy volunteers, in contrast to hMSC from cancer patients, significantly improved bone healing at 8, but not 16 weeks. However, at 16 weeks, hMSC significantly improved vasculogenesis in residual defect. We conclude that hMSC from healthy donors significantly contributed to the healing of bone defects at 8 weeks and to the vascularisation of residual connective tissue for up to 16 weeks. We found the administration of hMSC to be safe, as no adverse reaction to human cells at the site of implantation and no evidence of migration of hMSC to distant organs was detected.

BMP-2-coated mineral coated microparticles improve bone repair in atrophic non-unions.

Atrophic non-unions are a major clinical problem. Mineral coated microparticles (MCM) are electrolyte-coated hydroxyapatite particles that have been shown in vitro to bind growth factors electrostatically and enable a tuneable sustained release. Herein, we studied whether MCM can be used in vivo to apply Bone Morphogenetic Protein-2 (BMP-2) to improve bone repair of atrophic non-unions. For this purpose, atrophic non-unions were induced in femurs of CD-1 mice (n = 48). Animals either received BMP-2-coated MCM (MCM + BMP; n = 16), uncoated MCM (MCM; n = 16) or no MCM (NONE; n = 16). Bone healing was evaluated 2 and 10 weeks postoperatively by micro-computed tomographic (µCT), biomechanical, histomorphometric and immunohistochemical analyses. µCT revealed more bone volume with more highly mineralised bone in MCM + BMP femurs. Femurs of MCM + BMP animals showed a significantly higher bending stiffness compared to other groups. Histomorphometry further demonstrated that the callus of MCM + BMP femurs was larger and contained more bone and less fibrous tissue. After 10 weeks, 7 of 8 MCM + BMP femurs presented with complete osseous bridging, whereas NONE femurs exhibited a non-union rate of 100 %. Of interest, immunohistochemistry could not detect macrophages within the callus, indicating a good biocompatibility of MCM. In conclusion, the local application of BMP-2-coated MCM improved bone healing in a challenging murine non-union model and, thus, should be of clinical interest in the treatment of non-unions.

Pulsed electromagnetic field inhibits RANKL-dependent osteoclastic differentiation in RAW264.7 cells through the Ca2+-calcineurin-NFATc1 signaling pathway

Pulsed electromagnetic field (PEMF) has been reported to improve bone healing in osteoporosis patients. However, the precise mechanism has remained largely unknown. This study aimed to investigate the effects of PEMF on nuclear factor κB ligand (RANKL)-dependent osteoclastic differentiation and the Ca2+-calcineurin-NFATc1 signaling pathway in RAW264.7 cells in vitro. Treating RAW264.7 cells with RANKL for 4 days induced osteoclastic differentiation in vitro, and the formation of multinucleated osteoclasts, bone resorption-pit formation, tartrate-resistant acid phosphatase (TRAP) activity and the protein levels of cathepsin K, TRAP, Nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1) and matrix metalloproteinase 9 (MMP-9) were significantly decreased. The mRNA levels of specific genes related to osteoclastogenesis (TRAP, NFATc1, CTSK and MMP-9) were also reduced. Moreover, the oscillations of intracellular Ca2+ in RANKL-dependent RAW264.7 cells were suppressed by PEMF, as well as by inhibitors of membrane and store-operated Ca2+ channels. Meanwhile, calcineurin activity was increased, although its protein level was not changed. PEMF increased phospho-NFATc1 in the cytosol while suppressing the nuclear translocation of NFATc1, thus inhibiting osteoclastic differentiation by suppressing the Ca2+-calcineurin-NFATc1 signaling pathway. Although many questions remain unresolved, to our knowledge, this is the first report demonstrating that PEMF is beneficial against RANKL-dependent osteoclastic differentiation in RAW264.7 cells in vitro via inhibiting the Ca2+-calcineurin-NFATc1 signaling pathway.

Local Administration of Bisphosphonate-soaked Hydroxyapatite for the Treatment of Osteonecrosis of the Femoral Head in Rabbit.

Background:Systemic administration of bisphosphonates has shown promising results in the treatment of osteonecrosis of the femoral head (ONFH). However, few studies have evaluated the efficacy of local zoledronate (ZOL) administration in the treatment of ONFH. The purpose of this study was to investigate whether local administration of bisphosphonate-soaked hydroxyapatite (HA) could improve bone healing in an experimental rabbit model of ONFH.Methods:This experimental study was conducted between October 2014 and June 2015. Forty-five rabbits underwent simulated ONFH surgery. Immediately following surgery, they were divided into three groups: model (untreated, n = 15), HA (treated with HA alone, n = 15), and HA + ZOL (treated with HA soaked in a low-dose ZOL solution, n = 15). Histological, immunohistochemical, and quantitative analyses were performed to evaluate bone formation and resorption 2, 4, and 8 weeks after surgery.Results:Gross bone matrix and hematopoietic tissue formation were observed in the HA + ZOL group 4 weeks after surgery. The immunohistochemical staining intensities for 5-bromodeoxyuridine, runt-related transcription factor 2, osteocalcin, osteopontin, and osteoprotegerin were significantly higher in the HA + ZOL group than that in the model (P < 0.001, P < 0.001, P < 0.001, P < 0.001, and P = 0.018, respectively) and HA groups (P = 0.003, P = 0.049, P < 0.001, P = 0.020, and P = 0.019, respectively), whereas receptor activator of the nuclear factor-κB ligand staining intensity was significantly lower in the HA + ZOL group than that in the model and HA groups (P = 0.029 and P = 0.015, respectively) 4 weeks after surgery. No significant differences in bone formation or bone resorption marker expression were found between the three groups 2 or 8 weeks after surgery (P > 0.05).Conclusions:Local administration of HA soaked in a low-dose ZOL solution increased new bone formation while inhibiting bone resorption in an animal model of ONFH, which might provide new evidence for joint-preserving surgery in the treatment of ONFH.