Enhance Bone Healing Research Articles

Histological and Immunohistochemical Evaluation of Local Exogenous Application of the Green Tea on Bone Healing (Experimental Study On Rats)

Background: The study was designed to identify the role of local exogenous green tea in bone healing . Material and method: Thirty male albino rats, were subjected for bone defects in medial sides of both tibia bone (right tibia was considered as experimental site with 1μl of extract green tea, while the left be the control one, (treated with 1μl of normal saline). The rats were scarified at 3,7,10 days post surgery. Bone healing was histologically examined with immunohistochemical for local- ization of bone morphogenic protein 2. Results : show bone healing treated with extracted green tea illustrated to be faster in apposition of ostoid and bone trabeculae that is detected to fill the most of bone defect in comparism with control group. Conclusion: Our results indicate that low application of exogenous green tea could be an effective therapeutic for bone injures, these data are promising for a possible future clinical usage especially for enhancement of bone healing.

Investigation of the inner corrosion layer formed in pulse electrodeposition coating on Mg-Sr alloy and corresponding degradation behavior

Magnesium-based metals are considered as promising biodegradable orthopedic implant materials due to their potentials of enhancing bone healing and reconstruction, and in vivo absorbable characteristic without second operation for removal. However, the rapid corrosion has limited their clinical applications. Ca-P coating by electrodeposition has been supposed to be effective to control the degradation rate and enhance the bioactivity. In this work, a brushite coating was fabricated on the Mg-Sr alloy by pulse electrodeposition (PED) to evaluate its efficacy for orthopedic application. Interestingly, an inner corrosion layer was observed between the PED coating and the alloy substrate. Meanwhile the results of in vitro immersion and electrochemical tests showed that the corrosion resistance of the coated alloy was undermined in comparison with the uncoated alloy. It was deduced that the existence of this corrosion layer was attributed to the worse corrosion performance of the alloy. The mechanism on formation of the inner corrosion layer and its influence on consequent degradation were analyzed. It can be concluded that the electrodeposition coating should be not suitable for those magnesium alloys with poor corrosion resistance such as the Mg-Sr alloy. More importantly, it should be noted that the process of coating formation combined with the nature of substrate alloy is important to evaluate the efficacy of coating for biodegradable Mg-based implants application.

Functional synergy of anti-mir221 and nanohydroxyapatite scaffold in bone tissue engineering of rat skull

An appropriate cell source, effective cell modification, and proper supportive matrices are the main bases of tissue engineering. The effectiveness of anti-mir221 or hydroxyapatite (HA) in improving the osteogenic differentiation of mesenchymal stem cells (MSCs) has been reported previously. Herein, simultaneous application of these osteogenic inducers was investigated in vivo. The Poly-caprolactone (PCL)/HA nanofibers were characterized using contact angle measurement, tensile test, Fourier transform infrared spectroscopy, and electron microscopy. Rat MSCs were isolated, characterized and transfected with anti-mir221. The rats were divided into 4 groups and an 8mm defect were created in the mid-calvaria of each rat by trephine bur. Group 1 received (PCL)/HA nanofibers, group 2 received (PCL)/HA nanofibers plus autologous MSCs, group 3 received (PCL)/HA nanofibers plus MSCs transfected with anti-mir221, and group 4 rats were left empty as an additional control group. Histomorphometric and radiomorphometric evaluation after 4 and 8weeks revealed more new bone formation in the cell-treated groups compared to the scaffold alone group. There was evidence for a combination of increased osteoclasts and osteoblast vascular lake containing red blood cells in the anti-mir221 transfected group. New bone penetration into the scaffolds empirically demonstrated the capability of this combination for efficient osteointegration. Altogether, the co-application of HA and anti-mir221 transfected cells can enhance bone healing of the rat skull.

Effects on the osseointegration of titanium implants incorporating calcium-magnesium: a resonance frequency and histomorphometric analysis in rabbit tibia.

This study assessed the bone formation around titanium surface incorporating the calcium-magnesium (CaMg) deposited by blasted in rabbit tibia bone to determine whether this surface would further enhance bone healing compared with commercially available implant surface. The deposition of CaMg on the titanium SLA surface were obtained by blasting formed the experimental group (EX group), while implants with traditional SLA surface were used as control group (CO group), in this study. Fifty cylindrical threaded implants with a length of 8mm were used (P=25 per group). Five implants of each group were used to surface characterization by scanning electron microscopy, energy dispersive spectrometry, and optical profilometry. Ten New Zealand white rabbits received 40 implants (n=20 per group). Resonance frequency analysis was performed three times (0, 4, and 6weeks). Histomorphometric analysis was performed 4 and 6weeks after implantation. Statistical significance was set at P<0.05. Blasted CaMg deposition on SLA implant surface displayed almost identical surface morphologies and R(a) values at the micron scale. In comparing the implant stability quotient at the three time points, highly significant statistic differences were found (P<0.001). Histomorphological analysis showed higher degrees of bone organization in the samples of test implant surfaces at both implantation times. Within the limitations of this study, the results indicate that the deposition of CaMg on the SLA titanium surface may be effective in enhancing the osseointegration of moderately rough grit-blasted implants by increasing the degree of bone-implant contact.

Treatment of Different Types of Bone Defects with Concentrated Growth Factor: Four Case Reports

Various techniques have been attempted in the past to truly regenerate the lost bone structures. Owing to its stimulatory effect on angiogenesis and epithelialization, concentrated growth factor (CGF) is an excellent material for enhancing bone healing. The purpose of these case series is to document the beneficial role of CGF in the healing of different bone defect areas. This report describes four female patients presented with (lateral cyst on tooth 22; periimplantitis on mandibular left first premolar area; furcation lesion on tooth 36, periapical abcess on teeth 11-21). Mucoperiosteal full-thickness flaps were elevated to perform the surgical debridement of lesion areas in all patients. Then, minced CGF mixed with bone graft was applied to fill the defects. Recall radiographs of cases showed satisfactory healing of the bony defects. According to the results obtained in these case reports, the positive clinical impact of additional application of CGF with bone graft materials in treatment of bone defects is based on significant radiographic defect bone fill.

Amorphous polyphosphate/amorphous calcium carbonate implant material with enhanced bone healing efficacy in a critical-size defect in rats

In this study the effect of amorphous calcium carbonate (ACC) microparticles and amorphous calcium polyphosphate (polyP) microparticles (termed aCa-polyP-MP) on bone mineral forming cells/tissue was investigated in vitro and in vivo. The ACC particles (termed ACC-P10-MP) were prepared in the presence of Na-polyP. Only the combinations of polyP and ACC microparticles enhanced the proliferation rate of human mesenchymal stem cells (MSCs). Gene expression studies revealed that ACC causes an upregulation of the expression of the cell membrane-associated carbonic anhydrase IX (CA IX; formation of ACC), while the transcript level of the alkaline phosphatase (ALP; liberation of orthophosphate from polyP) changes only relatively little. In contrast, aCa-polyP-MP primarily induces ALP expression. If both components are applied together a strong stimulation of expression of both marker genes is observed. In order to investigate whether ACC also enhances bone regeneration induced by polyP in vivo, the particles were encapsulated into PLGA (poly(d,l-lactide-co-glycolide)) microspheres (diameter ~800 μm) and implanted into rat critical-size calvarial defects. The studies revealed that animals that received aCa-polyP-MP microspheres showed an increased rate of regeneration compared to β-tri-calcium phosphate (β-TCP) controls. This effect is even accelerated if microspheres with both aCa-polyP-MP and ACC-P10-MP (1 : 1 weight ratio) are applied, resulting in an almost complete restoration of the defect area after 12 weeks. qRT-PCR analyses of tissue sections through the regeneration zone with microspheres containing both aCa-polyP-MP and ACC-P10-MP revealed a significantly higher upregulation of expression of the marker genes compared to each of the components alone. The Young’s moduli for microspheres containing aCa-polyP-MP (1.74 MPa) and aCa-polyP-MP/ACC-P10-MP (2.38 MPa) were markedly higher compared to β-TCP-controls (0.63 mPa). Our results show that the combined application of ACC and Ca-polyP (both in the amorphous state) opens new strategies for the development of regenerative implants for the reconstruction of bone defects.

Managing lateral tibial plateau fractures by reversed 3.5 mm buttress plate: A report of four cases

Osteonecrosis is a common disorder of bone, which if left untreated, will lead to progressive collapse of bone, and degeneration of the overlying articular cartilage. Recently, new techniques have been developed in which the osteonecrotic lesion is drilled (core decompression) and/or more extensively debrided, and osteoprogenitor cells from the iliac crest are harvested, concentrated and delivered to the lesion to enhance bone healing. In the earlier stages of osteonecrosis of the hip and knee without collapse or arthritic changes in the involved joint, the intermediate term results for preserving (rather than replacing) the joint using these techniques have been very encouraging. Future basic and clinical research is necessary to develop evidence-based algorithms to optimize patient selection, cell harvesting, expansion and delivery, preparation of the osteonecrotic lesion, biomechanical support and appropriate rehabilitation protocols.

OSTEOGROW: BMP6 device for enhance bone healing

Searchable abstracts of presentations at key conferences on calcified tissues ISSN 2052-1219 (online)

Bone Regenerative Potential of Enamel Matrix Protein in the Circumferential Defect Around a Dental Implant.

The aim of this study was to determine the bone regenerative potential of enamel matrix derivative (EMD) in a defect around a dental implant. Five mongrel dogs were used. A circumferential defect was created around osteotomies that had been fabricated to receive titanium implants. The defects were treated with EMD, biphasic calcium phosphate (BCP), a mixture of EMD and BCP (EBCP), or blood coagulum (control). In general, the amount of new bone formation, the most-coronal level of bone-implant contact, defect fill, and bone-implant contact ratio were greater in the EMD group than in the control group, but the differences did not reach statistical significance. The EBCP group yielded no beneficial effect in new bone formation. Histologically, there was no notable difference in healing pattern between the EMD group and the control, and the EBCP and the BCP group. Few of the specimens in the EMD and EBCP groups exhibited remarkable bone regeneration. Neither EMD alone nor a mixture of BCP and EMD enhanced bone healing in a circumferential gap defect around a dental implant.

Enhancement of Bone-Healing by Low-Intensity Pulsed Ultrasound: A Systematic Review.

Low-intensity pulsed ultrasound (LIPUS) is frequently used to enhance or to accelerate fracture-healing, but its clinical role and effectiveness as a treatment modality remain uncertain. We performed a systematic review and meta-analysis of randomized controlled trials to determine the efficiency of LIPUS on bone-healing and/or fracture union, as well as on functional recovery. The databases of PubMed/MEDLINE, Cochrane Central Register of Controlled Trials, CINAHL, Web of Science, and Embase were searched for trials concerning LIPUS stimulation and bone-healing or fracture repair, in any language, published from the inception of the database to January 2, 2015. Eligible studies were randomized controlled trials that enrolled patients with any type of fracture, delayed union, or nonunion and randomly assigned them to LIPUS treatment or a control group. Two reviewers independently agreed on eligibility, assessed methodological quality, and extracted outcome data. All relevant outcomes were pooled, and a meta-analysis was performed. Twenty-four unique randomized trials were selected for analysis after the search of all databases and the inclusion of one trial by the senior author. Time to radiographic fracture union was the most common primary outcome measure evaluated. After pooling the data concerning time to radiographic healing in the combined patient population (n = 429), LIPUS treatment resulted in a mean reduction in healing time of 39.8 days (95% confidence interval, 17.7 to 62.0 days; I = 94%). The most reduction in time to radiographic union by LIPUS treatment was seen in fractures with a long natural healing tendency. Three trials evaluating the time to return to work or active duty, as a surrogate for functional recovery, were unable to demonstrate a beneficial effect of LIPUS (n = 179). Evidence from two high-quality trials implied that LIPUS enhances fracture-healing through increased bone formation in cases of delayed and/or impaired bone-healing. The prevention of delayed union or nonunion by LIPUS treatment could not be demonstrated. LIPUS treatment effectively reduces the time to radiographic fracture union, but this does not directly result in a beneficial effect of accelerated functional recovery or the prevention of delayed union or nonunion. The increase in bone formation as a result of LIPUS treatment may provide a valuable tool in fracture repair, but it does not always lead to healing. Future studies should focus on reporting of a combination of subjective signs of clinical healing, functional recovery, and radiographic union to determine the effectiveness of LIPUS treatment in clinical fracture-healing. Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Modulating macrophage polarization with divalent cations in nanostructured titanium implant surfaces

Nanoscale topographical modification and surface chemistry alteration using bioactive ions are centrally important processes in the current design of the surface of titanium (Ti) bone implants with enhanced bone healing capacity. Macrophages play a central role in the early tissue healing stage and their activity in response to the implant surface is known to affect the subsequent healing outcome. Thus, the positive modulation of macrophage phenotype polarization (i.e. towards the regenerative M2 rather than the inflammatory M1 phenotype) with a modified surface is essential for the osteogenesis funtion of Ti bone implants. However, relatively few advances have been made in terms of modulating the macrophage-centered early healing capacity in the surface design of Ti bone implants for the two important surface properties of nanotopography and and bioactive ion chemistry. We investigated whether surface bioactive ion modification exerts a definite beneficial effect on inducing regenerative M2 macrophage polarization when combined with the surface nanotopography of Ti. Our results indicate that nanoscale topographical modification and surface bioactive ion chemistry can positively modulate the macrophage phenotype in a Ti implant surface. To the best of our knowledge, this is the first demonstration that chemical surface modification using divalent cations (Ca and Sr) dramatically induces the regenerative M2 macrophage phenotype of J774.A1 cells in nanostructured Ti surfaces. In this study, divalent cation chemistry regulated the cell shape of adherent macrophages and markedly up-regulated M2 macrophage phenotype expression when combined with the nanostructured Ti surface. These results provide insight into the surface engineering of future Ti bone implants that are harmonized between the macrophage-governed early wound healing process and subsequent mesenchymal stem cell-centered osteogenesis function.

Clinical and radiographic evaluation of the influence of antihyperglycemic drug (metformin) on healing of bone and periodontal defects after impacted mandibular third molar surgery

Objectives The purpose of the current study was to clinically and radiographically assess the regenerative potential of metformin in enhancement of bone healing in third molar extraction sites. Patients and methods The present study included 40 healthy volunteers (27 females and 13 males) aged 21-27 years who had been scheduled for surgical removal of their impacted mandibular third molars. Volunteers were randomly assigned to either groups A or B. Twenty patients of group A (test) underwent surgical removal of impacted mandibular third molar followed by application of metformin gel in the surgical site. Twenty patients of group B (control) underwent surgical removal of impacted mandibular third molar only. Clinical and radiographic evaluation (cone beam computed tomography) was performed immediately after operation and at 6 months postoperatively in terms of the probing pocket depth, the bone defect length at the distal side of second lower molars, and bone density. Data were collected and statistical analysis was performed. Results At 6 months postoperatively group A (test) showed significantly higher (P ≤ 0.001) mean bone density compared with group B (control). On the other hand, there was nonsignificant (P ≥ 0.001) difference in the periodontal pocket depth and defect length between the test and control groups after 6 months. Conclusion There was a significant improvement regarding bone density at the surgical site using metformin after impacted mandibular third molar removal. Thus bone-formative effects of the common oral antihyperglycemic agent MF can provide a new direction in the field of bone healing.

Sustained delivery of thymoquinone and epigallocatechin-3 gallate to potentiate osteogenesis in a femoral rat defect rat model

Event Abstract Back to Event Sustained delivery of thymoquinone and epigallocatechin-3 gallate to potentiate osteogenesis in a femoral rat defect rat model Hamed A. Benghuzzi1 and Michelle A. Tucci1 1 Universitry of Mississippi Medical Center, United States Introduction: The goal of this study is to explore, for the first time, the capability of Tricalcium Phosphate Lysine (TCPL) ceramic implants to deliver Thymoquinone (TMQ) and epigallocatechin-3 gallate (EGCG), in a sustained manner using femoral defect animal model. The hypothesis of this project is that the use of alternative anti-oxidant based therapy can provide an ideal means to promote osteogenesis in femoral traumatized model. Black Seed herb contains over 100 components, many of which are yet to be discovered. The common one that is thought to be of medicinal value is TMQ [1]. It is a rich source of unsaturated fatty acids and contains about 35% oil, 21% protein, and 38% carbohydrates. More than 50% of the oil are essential fatty acids. EGCG is a potent anti-inflammatory molecule found in green tea. Previous studies have documented that EGCG intake promoted cardiovascular efficiency along with anti-rheumatic activity. Materials and Methods: Adult male rats were randomly divided into 5 groups of 5 each. Group I were untreated and served as intact control. Group II animals were implanted with the TCPL capsule loaded with antibiotic (30 mg Vancomycin (VC)) alone. Groups III-V animals were implanted with TCPL capsule containing VC+TMQ (20mg), VC+EGCG (20mg) and VC+EGCG (20mg)+TMQ (20mg); respectively. Generally, an incision was made to expose the left hind femur where a hole was drilled using a #6 dental bar (2 mm). Each TCPL capsule was implanted at a close proximity to the femoral defect. Fabrication of Ceramics: The microcrystals of TCP were prepared by following a method developed by Benghuzzi and Bajpai [2][3]. Protein Determination: Total protein content in all experimental and control groups was determined using Pierce BCA method [2]. Morphometric Analysis: All morphological analysis were done utilizing the Image Pro Software. Data Analysis: Sigma Stat Software, Jandel Inc. and Slide Write Software were used to determine and compute statistical significance and produce graphical representations of the results. Analysis of variance was used to compare the groups ad significance differences reported at p<0.05. Results and Discussion: Results obtained from this study demonstrated that TCPL delivery system was capable of releasing EGCG, TMQ alone or in combination at sustained levels for 30 days. The release profiles of both agents ranged between 4.35+/-0.12 and 6.78+/- 0.24 ng/ml. Data obtained revealed that there were no significant changes in body weights of animals treated with either EGCG or TMQ compared to the control group. The levels of proteins in all the groups were observed to be fluctuating as the measurements were done for the four different sampling periods. However, there were no significant differences between the groups for specific sampling dates. The levels of alkaline phosphatase continued to decline with time, however, there were no statistical differences between the groups was noted (p<0.05). All animals exposed to a combination of EGCG+TMQ showed extensive bone ingrowth suggestive of a synergistic effect compared to animals exposed to individual agents (moderate ingrowth). Conclusions: It appears that sustained delivery of TMQ can enhance bone healing with little or no side effects on major vital and reproductive organs. Despite the fact that there is barely any work documented done previously using TMQ+EGCG in an attempt to test its viability in healing fractures, the results obtained in this experiment were promising. Therefore, calls for the need of comprehensive studies to establish mode of action of sustained delivery of TMQ+EGCG.

Cell signalling and bone remodelling Part II: Developments in the pathogenesis and principles of management of selected skeletal disease states

Mapping of the bone remodelling signalling pathways contributed significantly to the establishment of a scientific basis for the development of pharmaceuticals which have the potential to induce or suppress bone formation. Enhancing bone healing and the establishment of a pre-determined skeletal phenotype are now within reach of the medical profession. This manuscript provides practitioners with an overview of recent developments in the quest for uncovering the molecular mechanisms involved in the pathogenesis of selected bone disease states and the role these discoveries play in the future management of bone healing and skeletal health.

Structural and mechanical characterizations of nano calcium phosphate coatings prepared by induction suspension plasma spray (rf-SPS)

Event Abstract Back to Event Structural and mechanical characterizations of nano calcium phosphate coatings prepared by induction suspension plasma spray (rf-SPS) Frédéric Faivre1, 2, Max Loszach2, Ghislaine Bertrand1, François Gitzhofer2, Joel Alexis3, Jade Pecune3, David Grossin1 and Christian Rey1 1 CIRIMAT, Université de Toulouse, France 2 Université de Sherbrooke, Département de génie chimique et génie biotechnologique, Canada 3 LGP, Université de Toulouse, France Introduction: Among the variety of coating technologies developed to deposit stoichiometric hydroxyapatite, plasma spraying is the most widely used technique implemented by industry to treat prosthetic devices.[1] The good biocompatibility and osteoconductivity of this material have been found to enhance bone healing at early implantation time but long-term stability is still controversial. The mechanisms which are responsible for this change can be related to instability of the coating/bone tissue interface (dissolution at neutral pH, resorption by osteoclasts) or of the coating/implant interface (delamination due to stress, preferential dissolution of amorphous phase, poor initial adhesion).[2] To find an optimal and sustainable integration, a nanostructured substituted hydroxyapatite coating mimicking the complex surface topography (roughness, grain size, porosity) and structure (Ca/P ratio, stoichiometry, crystallinity) of the mineral part of the natural bone was produced implementing the suspension/solution inductively rf coupled plasma spray system.[3] The objective of the present study is to assess the influence of operating conditions (suspension composition, power, pressure, gas composition, spraying distance) on coating/TA6V substrate adherence and coating physical and structural characteristics. Materials and Methods: Hydroxyapatite and substituted hydroxyapatite (Mg,Na,K)xCa10-x(PO4)6(F,Cl)y(OH)2-y coatings have been produced using a 50 kW inductively coupled RF plasma spray system operating at 3 MHz and equipped with a suspension feeder nozzle (Tekna Plasma System Inc.). The structural characteristics were determined by XRD, FTIR and Raman spectroscopies, the chemical compositions by ICP or SAAF and the morphology by SEM. Qualitative and quantitative determination of the phases, including the crystallinity of the coatings has been carried using Rietveld refinement. Micro and nano hardness tests were performed to evaluate the Young modulus and coating cohesion. 3-points bending tests with stiffener were applied to determine the coating adhesion. Results and Discussion: The spraying chamber pressure, the power, the liquid/solid phase ratio in the suspension and the spraying distance have a strong influence on the CaP phases. It was demonstrated that the optimized coating was mainly constituted of HA (91 vol.%) with nanometric sizes (below 100 nm). The secondary phases were (a-TCP, β-TCP, CaO and TTCP) as usually in plasma sprayed calcium phosphate coatings. Furthermore, it was showed that multisubstituted hydroxyapatite coating is achievable by suspension plasma spray. Coating roughness was around 5 µm and could be adapted thanks to substrate surface treatment. Finally mechanical properties of optimized coatings exhibited similar values (bending test Fc=140N, hardness test E=7±2 GPa, H=2.5±1 GPa) to the ones of a commercial HA coating (Fc=100 to 160 N, E=10 GPa, H=1.5 to 3 GPa). Conclusion: Both physical and structural characteristics can be tuned by adjusting the operating plasma spray parameters in order to favor the nanometric grain size, crystallinity (targeted phase HA), adhesion and cohesion as well as complex compositions. We would like to thank the CPCFQ-biennum 2013-2014 for providing financial support to this project during two years.

Exercise and Anti-Osteoporotic Medication Combined Treatment for Osteoporosis

Antiosteoporotic medications are often used to reduce fracture risk and treat osteoporosis. Similarly, regular physical activity also plays an important role in both maintaining and improving bone density. Recently, it has been shown that exercise combined with osteoporosis medications may produce greater benefits on bone associated with osteoporosis than either intervention alone. This commentary evaluates the current literature mostly produced in our laboratory from animal models to determine the optimal combination of physical exercise and medications on osteoporosis induced by ovariectomy and exogenous glucocorticoids. The data suggest that both approaches enhance bone healing, however the combined effects of these two therapies do not appear to produce any remarkable synergetic or additive effects. Clinical studies are needed to fully understand the effects of exercise and selective medications on bone remodelling in order to optimise treatment of fragility fractures in patients with underlying osteoporosis.

Combination therapy with BMP-2 and a systemic RANKL inhibitor enhances bone healing in a mouse critical-sized femoral defect

Recombinant human BMP-2 (rhBMP-2) is a potent osteoinductive agent, but has been associated not only with bone formation, but also osteoclastogenesis and bone resorption. Osteoprotegerin (OPG) is a RANKL inhibitor that blocks differentiation and function of osteoclasts. We hypothesized that the combination of local BMP-2 (recombinant protein or a product of gene therapy) plus systemic OPG-Fc is more effective than BMP-2 alone in promoting bone repair. To test this hypothesis we used a mouse critical-sized femoral defect model. Col2.3eGFP (osteoblastic marker) male mice were treated with rhBMP-2 (group I), rhBMP-2 and systemic OPG (group II), rhBMP-2 and delayed administration of OPG (group III), mouse BM cells transduced with a lentiviral vector containing the BMP-2 gene (LV-BMP-2; group IV), LV-BMP-2 and systemic OPG (group V), a carrier alone (group VI) and administration of OPG alone (group VII). All bone defects treated with BMP-2 (alone or combined with OPG) healed, whereas minimal bone formation was noted in animals treated with the carrier alone or OPG alone. MicroCT analysis showed that bone volume (BV) in rhBMP-2+OPG and LV-BMP-2+OPG groups was significantly higher compared to rhBMP-2 alone (p<0.01) and LV-BMP-2 alone (p<0.001). Similar results were observed in histomorphometry, with rhBMP-2 alone defects exhibiting significantly lower bone area (B.Ar) compared to rhBMP-2+OPG defects (p<0.005) and LV-BMP-2 defects having a significantly lower B.Ar compared to all BMP-2+OPG treated groups (p≤0.01). TRAP staining demonstrated a major osteoclast response in the groups that did not receive OPG (rhBMP-2, LV-BMP-2 and sponge alone) beginning as early as 7days post-operatively. In conclusion, we demonstrated that locally delivered BMP-2 (recombinant protein or gene therapy) in combination with systemically administered OPG improved bone healing compared to BMP-2 alone in a mouse critical-sized bone defect. These data indicate that osteoclasts can diminish healing responses to BMP-2 and that RANKL inhibition may thus accentuate BMP-2 efficacy.

Effect of osteoporosis medications on fracture healing.

Antiosteoporotic medications are often used to concurrently treat a patient's fragility fractures and underlying osteoporosis. This review evaluates the existing literature from animal and clinical models to determine these drugs' effects on fracture healing. The data suggest that these medications may enhance bone healing, yet more thorough prospective studies are warranted. Pharmacologic agents that influence bone remodeling are an essential component of osteoporosis management. Because many patients are first diagnosed with osteoporosis when presenting with a fragility fracture, it is critical to understand how osteoporotic medications influence fracture healing. Vitamin D and its analogs are essential for the mineralization of the callus and may also play a role in callus formation and remodeling that enhances biomechanical strength. In animal models, antiresorptive medications, including bisphosphonates, denosumab, calcitonin, estrogen, and raloxifene, do not impede endochondral fracture healing but may delay repair due to impaired remodeling. Although bisphosphonates and denosumab delay callus remodeling, they increase callus volume and result in unaltered biomechanical properties. Calcitonin increases cartilage formation and callus maturation, resulting in improved biomechanical properties. Parathyroid hormone, an anabolic agent, has demonstrated promise in animal models, resulting in accelerated healing with increased callus volume and density, more rapid remodeling to mature bone, and improved biomechanical properties. Clinical data with parathyroid hormone have demonstrated enhanced healing in distal radius and pelvic fractures as well as postoperatively following spine surgery. Strontium ranelate, which may have both antiresorptive and anabolic properties, affects fracture healing differently in normal and osteoporotic bone. While there is no effect in normal bone, in osteoporotic bone, strontium ranelate increases callus bone formation, maturity, and mineralization; forms greater and denser trabeculae; and improves biomechanical properties. Further clinical studies with these medications are needed to fully understand their effects on fracture healing in order to simultaneously treat fragility fractures and underlying osteoporosis.

Placement-induced effects on high tibial osteotomized construct - biomechanical tests and finite-element analyses.

BackgroundHigh tibial osteotomy (HTO) with a medially opening wedge has been used to treat osteoarthritic knees. However, the osteotomized tibia becomes a highly unstable structure and necessitates the use of plate and screws to stabilize the medial opening and enhance bone healing. A T-shaped plate (e.g. TomoFix) with locking screws has been extensively used as a stabilizer of the HTO wedge. From the biomechanical viewpoint, however, the different plate sites and support bases of the HTO plate should affect the load-transferring path and wedge-stabilizing ability of the HTO construct. This study uses biomechanical tests and finite-element analyses to evaluate the placement- and base-induced effects of the HTO plates on construct performance.MethodsTest-grade synthetic tibiae are chosen as the standard specimens of the static tests. A medial wedge is created for each specimen and stabilized by three plate variations: hybrid use of T- and I-shaped plates (TIP), anteriorly placed TomoFix (APT), and medially placed TomoFix (MPT). There are five tests for each variation. The failure loads of the three constructs are measured and used as the load references of the fatigue finite-element analysis. The residual life after two hundred thousand cycles is predicted for all variations.ResultsThe testing results show no occurrence of implant back-out and breakage under all variations. However, the wedge fracture consistently occurs at the opening tip for the APT and MPT and the medially resected plateau for the TIP, respectively. The testing results reveal that both failure load and wedge stiffness of the TIP are the highest, followed by the MPT, while those of the APT are the least (P < 0.05). The fatigue analyses predict comparable values of residual life for the TIP and MPT and the highest value of damage accumulation for the APT. Both experimental and numerical tests show the biomechanical disadvantage of the APT than their counterparts. However, the TIP construct without locking screws shows the highest stress at the plate-screw interfaces.ConclusionsThis study demonstrates the significant effect of placement site and support base on the construct behaviors. The TIP provides a wider base for supporting the HTO wedge even without the use of locking screws, thus significantly enhancing construct stiffness and suppressing wedge fracture. Compared to the APT, the MPT shows performance more comparable to that of the TIP. If a single plate and a smaller incision are considered, the MPT is recommended as the better alternative for stabilizing the medial HTO wedge.

Biodistribution of LV-TSTA transduced rat bone marrow cells used for "ex-vivo" regional gene therapy for bone repair.

"Ex vivo" regional gene therapy using lentiviral (LV) vectors to over-express bone morphogenetic protein 2 (BMP-2) is an effective way to enhance bone healing in animal models. Here, we evaluated two different "ex vivo" approaches using either "same day" rat bone marrow cells (SDRBMCs) or cultured rat bone marrow cells (C-RBMCs), both transduced with a LV based two-step transcriptional activation system overexpressing GFP (LV-TSTA-EGFP), to assess the fate of the transduced cells and the safety of this approach. The transduced cells were implanted in femoral defects of syngeneic rats. Animals were sacrificed at 4, 14, 28 and 56 days after surgery (n=5 per group). Viral copies were detectable in the defect site of SD-RBMC group and gradually declined at 8w (5 log decrease compared to 4d). In the C-RBMC animals, there was a 2-4 log decline in the viral copy numbers at 2w and 4w, but at 8w there was a relative rise (about 100 fold) in the number of the viral vectors in the defect site of 4 (out of 5) animals compared to the previous time points. For both gene transfer approaches, the pattern of tissue distribution was non-specific and no histological abnormalities were noted in either group. In summary, we demonstrated that the LV-TSTA transduced cells remain in the defect site for at least 56 days, though the numbers decreased over time. There were no consistent findings of viral copies in internal organs which is encouraging with respect to the development of this strategy for use in humans.