The effects of local and systemic alendronate delivery on wear debris‐induced osteolysis in vivo

We investigated the effects of locally and systemically administered alendronate on wear debris‐induced osteolysis in vivo. Endotoxin‐free titanium particles were injected into rabbit femurs, prior to insertion of a nonweight‐bearing polymethylmethacrylate plug into the distal femur canal. Then the particles were repeatedly injected into the knee 2, 4, and 6 weeks after the implantation. Alendronate was incorporated at three different concentrations (0.1, 0.5, and 1.0 wt %) into bone cement for local delivery. For systemic delivery, alendronate was subcutaneously injected (1.0 mg/kg/week) 1 week after the implantation and then once a week until sacrifice. Eight weeks postoperatively, there was significant evidence of osteolysis surrounding the plug in the control group compared with markedly blocked osteolysis in the 0.5 wt % and the 1.0 wt % groups, and the systemic group. There was a concentration‐dependent effect of alendronate‐loaded bone cement on the improvement of peri‐prosthetic bone stock. Notably, no significant differences were found between the 0.5 wt % and the systemic group in peri‐prosthetic bone stock and implant fixation. Collectively, although the biological efficacy after the systemic delivery of alendronate was slightly higher than that in the local treatment groups, alendronate‐loaded bone cement may be therapeutically effective in inhibiting titanium particle‐induced osteolysis in vivo. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:893–899, 2010     

红霉素抑制磨损颗粒诱发体内骨溶解的研究

[目的]通过小鼠体内磨损颗粒颅骨溶解模型研究红霉素(erythromycin,EM)抑制磨损颗粒诱发骨溶解的效果。[方法]24只8周龄的C57BL/J6雄性小鼠随机分为4组:聚甲基丙烯酸甲酯(polymethyl-methacrylate,PM-MA)组接受PMMA30 mg颗粒植入颅顶部,PMMA 2EM组接受30 mg PMMA颗粒植入加每天EM2 mg/kg腹腔内注射,PMMA 10EM组接受PMMA30 mg颗粒植入加每天EM10 mg/kg腹腔内注射,对照组接受假手术。7 d后取出颅骨进行病理学分析。[结果]颅骨破坏面积对照组为0.079 mm2±0.011 mm2,PMMA组0.335 mm2±0.129 mm2,PM-MA 2EM组0.094 mm2±0.019 mm2,PMMA 10EM组0.091 mm2±0.028 mm2。对照组颅骨实验区域内破骨细胞计数为5.3±1.0个,PMMA组为19.2±5.3个,PMMA 2EM组为6.6±1.1个,PMMA 10EM组为6.1±1.9个。与对照组相比,PMMA颗粒可以诱发骨溶解(P<0.001),而EM治疗可以抑制PMMA颗粒诱发的颅骨溶解(P<0.001),及破骨细胞生成(P<0.001)。[结论]EM可以抑制PMMA磨损颗粒诱发的骨溶解。     

Differential effects of biologic versus bisphosphonate inhibition of wear debris‐induced osteolysis assessed by longitudinal micro‐CT

Aseptic loosening of total joint replacements is caused by wear debris‐induced osteoclastic bone resorption, for which bisphosphonates (BPs) and RANK antagonists have been developed. Although BPs are effective in preventing metabolic bone loss, they are less effective for inflammatory bone loss. Because this difference has been attributed to the antiapoptotic inflammatory signals that protect osteoclasts from BP‐induced apoptosis, but not RANK antagonists, we tested the hypothesis that osteoprotegerin (OPG) is more effective in preventing wear debris‐induced osteolysis than zoledronic acid (ZA) or alendronate (Aln) in the murine calvaria model using in vivo micro‐CT and traditional histology. Although micro‐CT proved to be incompatible with titanium (Ti) particles, we were able to demonstrate a 3.2‐fold increase in osteolytic volume over 10 days induced by polyethylene (PE) particles versus sham controls (0.49 ± 0.23mm³ versus 0.15 ± 0.067mm³; p < 0.01). Although OPG and high‐dose ZA completely inhibited this PE‐induced osteolysis (p < 0.001), pharmacological doses of ZA and Aln were less effective but still reached statistical significance (p < 0.05). Traditional histomorphometry of the sagital suture area of calvaria from both Ti and PE‐treated mice confirmed the remarkable suppression of resorption by OPG (p < 0.001) versus the lack of effect by physiological BPs. The differences in drug effects on osteolysis were largely explained by the significant difference in osteoclast numbers observed between OPG versus BPs in both Ti‐ and PE‐treated calvaria; and linear regression analyses that demonstrated a highly significant correlation between osteolysis volume and sagittal suture area versus osteoclast numbers (p < 0.001). © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:1340–1346, 2008     

Expression of XBP1s in fibroblasts is critical for TiAl6V4 particle‐induced RANKL expression and osteolysis

Wear particle‐induced osteolysis is a major cause of aseptic loosening, which is one of the most common reasons for total hip arthroplasty (THA) failure. Previous studies have shown that the expression of Receptor activation of nuclear factor (NF)‐kB (RANKL) by fibroblasts in periprosthetic membrane played a crucial role in wear particle‐induced osteolysis. However, the underlying mechanism of RANKL expression remains largely unknown. In the present study, we investigated the effect of TiAl₆V₄ particle (TiPs)‐induced XBP1s (spliced form of X‐box binding protein 1) on RANKL expression and osteoclastogenesis both in vitro and in vivo. The levels of XBP1s in peri‐implant membrane, animal models, and TiPs‐stimulated fibroblasts were determined by western blots. To assess the effect of XBP1s on RANKL expression, fibroblasts were treated with both a small interfering RNA (siRNA) and an inhibitor of XBP1 prior to exposure to TiPs. The effect of XBP1s on osteoclasts formation was determined by tartrate‐resistant acid phosphatase (TRAP) staining in vitro osteoclastogenesis assay and in animal models. The resorption of bone was assessed by micro‐computed tomography (micro‐CT) with three‐dimensional reconstruction. Our results demonstrated that XBP1s was activated in periprosthetic membrane, mouse calvaria models, and TiPs‐stimulated human synovial fibroblasts. Further, inhibition of XBP1s decreased the expression of RANKL and osteoclasts formation in vitro. In mouse calvaria models, both of the osteoclastogenesis and osteolysis were inhibited XBP1s inhibitor. Our results suggested that XBP1s mediated TiPs‐induced of RANKL expression in fibroblasts, and down regulating XBP1s may represent a potential therapy for wear particle‐induced osteolysis. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:752–759, 2017.

     

Variation in the secreted frizzled‐related protein‐3 gene and risk of Osteolysis and heterotopic ossification after total hip arthroplasty

Secreted frizzled‐related protein‐3 (sFRP3) antagonizes ligands that promote new bone formation in adult tissues. We examined whether variation in the FRZB gene that encodes sFRP3 is associated with development of osteolysis or heterotopic ossification (HO) after total hip arthroplasty (THA). Genomic DNA was extracted from 609 subjects (osteolysis group n = 268) at a mean of 11 years following cemented THA for idiopathic osteoarthritis and genotyped for the FRZB Arg200Trp and Arg324Gly polymorphisms. The Brooker classification was used to assess HO following primary THA in 563 of the subjects. The carriage rate of the FRZB 200Trp allele was 14.2% in subjects with osteolysis versus 21.0% in controls (p = 0.041). The carriage rate of this allele was 21.7% in subjects with HO (n = 299) versus 12.0% in those without HO (p = 0.063). The odds ratio for osteolysis with carriage of FRZB 200Trp was 0.62 (95% CI 0.38 to 0.99; p = 0.049) and for HO was 1.64 (1.05 to 2.54; p = 0.028), after adjustment for the effects of other risk factors associated with the development of osteolysis or HO. Variants in the FRZB 324 locus alone were not associated with osteolysis or HO. However, the most frequent haplotype (FRZB 200Arg:324Arg) was associated with osteolysis (OR 1.50, 95% CI 1.09 to 2.07; p = 0.014). Our data suggest that the FRZB Arg200Trp locus may be a marker for pro‐osteoblastic activity after THA. Carriage of the FRZB 200Trp allele is associated with a “positive” bone balance phenotype (osteolysis ?: HO+). © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:1665–1670, 2007     

Contribution of micro‐motion to backside wear in a fixed bearing total knee arthroplasty

This study seeks to identify important factors related to backside wear of tibial inserts in vivo and determine an appropriate wear model for backside wear. An IRB approved database was queried for tibial inserts of a single design from one manufacturer that exhibited evidence of rotatory motion on the backside of the polyethylene. These devices were measured for volumetric wear using a previously established protocol. Features including the change in locking lip width and measurement of micro‐motion marks were used to describe the motion pattern. Volumetric wear and implant characteristics were compared using linear regressions by modeling wear theories suggested by Archard and Wang to determine the most appropriate model for backside wear. The Wang model showed that duration, adjusted sliding distance, and cross‐shear index accounted for approximately 58% of the volumetric wear variation while adjusted sliding distance and duration in vivo accounted for approximately 35% of the volumetric wear variation in the Archard model. Patient weight (p = 0.750), patient BMI (p = 0.680), and backside area (p = 0.784) of the tibial insert were all found to be non‐significant in the Wang model. Similarly, patient weight (p = 0.233), patient BMI (p = 0.162), and backside area (p = 0.796) were found to be non‐significant in the Archard model. Multidirectional micro‐motion appears to contribute significantly to the wear of these components, supporting the Wang theory of cross‐shear for polyethylene wear. Cross‐shear of polymers on an unpolished titanium tray can lead to an increase in wear debris in the body. Care should be taken when designing locking mechanisms and tray designs. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1933–1940, 2016.     

BMP induced inflammation: A comparison of rhBMP‐7 and rhBMP‐2

Concern has been raised because of reports of inflammatory swelling following the use of recombinant human bone morphogenetic protein‐2 (rhBMP‐2) and recombinant human bone morphogenetic protein‐7 (rhBMP‐7). The purpose of this study is to compare the inflammatory action of rhBMP‐7 with those of rhBMP‐2. ELISA assays (IL‐6, TNF‐α) were used to measure the cytokine response to different concentrations of rhBMP‐7 and ‐2. Recombinant human BMP‐7 was absorbed into absorbable collagen sponges and different amounts were implanted either subcutaneously (SC) or intramuscularly (IM) into the backs of rats. Using MRI and MIPAV software, we measured the degree of soft tissue edema at 3 h and at 2, 4, and 7 days postoperatively. After sacrificing rats on day 7 the inflammatory zone and mass were measured and the tissue examined histologically. Soft tissue edema after rhBMP‐7 and rhBMP‐2 implantation was dose‐dependent and peaked at 3 h for the subcutaneous implants and at 2 days for the intramuscular implants. RhBMP‐7 was associated with a significantly smaller soft tissue edema volume than was rhBMP‐2 only at the highest dose (20 µg/ml). Both rhBMP‐2 and rhBMP‐7 triggered dose‐dependent inflammatory reactions. Compared to rhBMP‐2, rhBMP‐7 is associated with somewhat smaller soft tissue edema volumes. Although rhBMP‐7 is associated with an inflammatory reaction leading to soft tissue edema, at high doses this response is significantly less than that seen with rhBMP‐2. Our animal model can be used to test materials that could ameliorate this reaction. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1985–1994, 2012     

An injectable composite material containing bone morphogenetic protein‐2 shortens the period of distraction osteogenesis in vivo

To investigate new methods that can decrease the duration of bone transport (BT) distraction osteogenesis, we injected composite materials containing recombinant human bone morphogenetic protein‐2 (BMP‐2) and induced the generation of a callus bridge by rapid segmental transport (4 mm/day) in a rabbit bone defect model. The composite materials consisted of BMP‐2 (0, 30, or 100 µg), β‐tricalcium phosphate powder (βTCP, 100 mg/animal; particle size, <100 µm), and polyethylene glycol (PEG; 40 mg/animal). A paste of equivalent composition was percutaneously injected at the lengthening and the docking sites after surgery and after BT, respectively. The radiographic, mechanical, and histological examinations 12 weeks post‐operative revealed that the generation of bridging callus in the presence and in the absence of BMP‐2 was significantly different. The callus mass in the bone defect region was adequately and consistently developed in the presence of 100 µg of BMP (administered for 6 weeks), and the bones were consolidated in 12 weeks. Such an adequate callus formation was not observed in the control animals without BMP‐2 treatment. The result of this experimental study suggests the potential application of BMP‐2 in accelerating callus formation and in enabling rapid bone transporting, thereby shortening the treatment period for the repair of diaphyseal bone defects by distraction osteogenesis. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:452–456, 2011     

Synthetic hydrogel scaffold is an effective vehicle for delivery of INFUSE (rhBMP2) to critical‐sized calvaria bone defects in rats

Medtronic's INFUSE Bone Graft provides surgeons with a potent tool for stimulating bone formation. Current delivery vehicles that rely on Absorbable Collagen Sponges (ACS) require excessive quantities of the active ingredient in INFUSE, recombinant human Bone Morphogenic Protein‐2 (rhBMP2), to achieve physiologically relevant concentrations of the growth factor, driving up the cost of the product and increasing the likelihood of undesirable side effects in neighboring tissues. We demonstrate that a simple light‐mediated, thiol‐ene chemistry can be used to create an effective polymer delivery vehicle for rhBMP2, eliminating the use of xenographic materials and reducing the dose of rhBMP2 required to achieve therapeutic effects. Comprised entirely of synthetic components, this system entraps rhBMP2 within a biocompatible hydrogel scaffold that is degraded by naturally occurring remodeling enzymes, clearing the way for new tissue formation. When tested side‐by‐side with ACS in a critical‐sized bone defect model in rats, this polymeric delivery system significantly increased bone formation over ACS controls. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 401–406, 2013     

Protective effects of udenafil citrate,piracetam and dexmedetomidine treatment on testicular torsion/detorsion‐induced ischaemia/reperfusion injury in rats

The aim of this study was to investigate the antioxidant properties of udenafil citrate (1.4 mg kg^?1–2.8 mg kg^?1), dexmedetomidine 25 μg kg^?1 and piracetam 200 mg kg^?1 administered on ipsilateral/contralateral testes after ischaemia in a rat model of testicular torsion/detorsion (T/D) and define its protective effect histologically. Fifty‐six Wistar albino rats were included and randomly assigned into 6 groups. No intervention was performed in control group (Group 1, n = 8) and in torsion/detorsion group, (Group 2, n = 8). Udenafil 1.4 mg kg^?1 was given to torsion/detorsion group (Group 3, n = 10), udenafil 2.8 mg kg^?1 was given to torsion/detorsion group (Group 4, n = 10), piracetam 200 mg kg^?1 was given to torsion/detorsion group (Group 5, n = 10) and dexmedetomidine 25 μg kg^?1 was given to torsion/detorsion group (Group 6, n = 10) intraperitoneally after 60 mins of testicular torsion. Biochemical and histopathological testicular injury were evaluated. When the tissue was examined by TOS values, Group 3, Group 4 and Group 5 were significantly lower than Group 2. In contrary Group 6 values were significantly higher than Group 2. The increasing doses of udenafil demonstrated antioxidant properties on the testis tissue and histopathological that protects the testicles.     

Material properties of bone in the femoral head treated with ibandronate and BMP‐2 following ischemic osteonecrosis

Bone morphogenetic protein (BMP)‐2 and ibandronate (IB) decrease the femoral head deformity following ischemic osteonecrosis of the femoral head (ONFH). The purpose of this study was to determine the effects of BMP‐2 and IB on the mineral content and nanoindentation properties of the bone following ONFH. ONFH was surgically induced in the femoral head of piglets. There were five groups: normal control, untreated, IB, BMP, and BMP + IB (n = 5/group). Backscattered electron imaging, Raman spectroscopy, and nanoindentation testing were performed. Both BMP and BMP + IB groups showed calcium content in the trabecular bone similar to the normal group, while the IB and no‐treatment groups showed a significant increase in the calcium content compared to the normal group. The carbonate content relative to phosphate was significantly increased in the IB and BMP + IB groups (p < 0.01) compared to the normal group. No significant difference was found between the BMP and the normal group. The nanoindentation modulus of the bone in the IB group was significantly increased compared to the normal group (p < 0.05). No significant differences were observed between the BMP and BMP + IB groups compared to the normal group. The nanoindentation hardness measurements in the IB group were also significantly increased compared to the BMP and BMP + IB groups (p < 0.05). In summary, trabecular bone treated with BMP or BMP + IB had material properties comparable to normal bone whereas the bone in the IB group retained the increased mineral content and the nanoindentation hardness found in the necrotic bone. Hence, BMP or BMP + IB better restores the normal mineral content and nanomechanical properties after ONFH than IB treatment alone. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1453–1460, 2017.