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Background The CIBOR PEEK spinal interbody fusion device is an anterior lumbar interbody fusion construct with a hollow center designed to accommodate an osteoinductive carbon foam insert to promote bony ingrowth to induce fusion where rigid stabilization is needed. Methods Three different sizes of the device were investigated. Part-I: implants were tested under axial compression and rotation using polyurethane foam blocks. Part-II: simulated 2-legged stance using cadaveric specimen using the L5-S1 lumbar spine segment. Part-III: a survey feedback form was used to investigate two orthopedic surgeons concern regarding the implant. Results In Part-I, the subsidence hysteresis under axial compression loading was found to be statistical significant difference between these three implant sizes. It was noted that the implants had migration as rotation applied, and the amount of subsidence was a factor of the axial compression loads applied. In Part-II, a minor subsidence and carbon foam debris were observed when compared to each implant size. Poor contact surface of the implant with the end plates of the L5 or S1 vertebrae from the anterior view under maximum loads was observed; however, the implant seemed to be stable. Each surgeon has their own subjective opinion about the CIBOR implant. Discussion Two out of the three different sizes of the device (medium and large sizes) provided appropriate rigid stabilization at the physiological loads. Neither orthopedic surgeon was 100% satisfied with overall performance of the implant, but felt potential improvement could be made. Clinical Relevance: This study indicates an option for operative treatment of spine interbody fusion, as the CIBOR spine interbody fusion device has a hollow center. This hollow center is designed to accommodate a carbon foam insert to promote bony ingrowth. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1157-1168, 2017. [ABSTRACT FROM AUTHOR]

This study investigated cellular trafficking and inflammatory markers in orthopedic biomaterial particle-challenged human peripheral blood monocytes (PBMCs) using a murine immunodeficiency (SCID) model. Periprosthetic tissues from aseptic loosening patients were transplanted into muscles of SCID mice. PBMCs from the same patients were stimulated in vitro with Ti-6Al-4V, PMMA, UHMWPE, or Co-Cr particles for 3 days before administered intraperitoneally to the periprosthetic tissue-implanted mice. The xenografts were harvested 2 weeks later for histological and molecular analyses. Significant cell infiltration was obvious in the transplanted tissues from mice transfused with Ti-alloy, PMMA and UHMWPE-provoked PBMCs compared to controls, and UHMWPE-provoked PBMCs group accumulated significantly more cells among all groups. There were ubiquitous TRAP+ stained cells in all xenografts from particle-stimulated PBMCs mice. Immunohistochemical staining indicated that significantly more IL-1β and TNF positive cells occurred in Ti and PMMA groups; while the UHMWPE group resulted in stronger positive MCP-1 and IL-6 stains. Polymerase chain reaction (PCR) confirmed overexpression of both IL-1β and TNF in Ti and PMMA-stimulated groups; and more MIP-1α gene expression developed in the UHMWPE group. Overall, different type of orthopedic materials influenced the trafficking ability of particle-activated PBMCs which may depend on upregulation of various proinflammatory cytokines and chemokines. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 358-364, 2015. [ABSTRACT FROM AUTHOR]

Biomimetic composites were constructed using anorganic bone to initiate the polymerization of cyclic lactones. The resulting anorganic bone/polylactone composites preserve the inorganic structure and the mechanical properties of the original bone. Thermal conditions used to prepare the anorganic bone were shown to control the surface functionalities, surface area, and crystallinity, all of which influence the rates of subsequent polymerizations. Thermal pretreatment of anorganic bone was examined as a function of time and temperature, ranging from 400°C to 800°C. Polymerization rates of different monomers were also compared. Additionally, in vitro evaluations of anorganic bone/poly- l-lactide and anorganic bone/polyglycolide composites for osteoblast and osteoclast competence suggest that these composites are good candidates for potential in vivo use, since both composites promoted osteoblast differentiation. The anorganic bone/poly- l-lactide composite also promoted osteoclast differentiation. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 1755-1766, 2014. [ABSTRACT FROM AUTHOR]

ABSTRACT We re-examined experimental model results using half-body specimens with intact extensor mechanisms and navigation to evaluate cruciate-retaining (CR) and posterior stabilized (PS) total knee arthroplasty (TKA) component gaps through an entire range of motion. Six sequential testing regimens were conducted with the knee intact, with a CR TKA in place, and with a PS TKA in place, with and without 22 N traction in place at each stage. Each of 10 knees was taken through six full ranges of motion from 0° to 120° at every stage using a navigated knee system to record component gapping. No significant difference was found between loaded and unloaded component gaps, and no significant differences were found in component gapping between CR and PS TKAs throughout a full range of motion. Flexion-extension gap measurements were significantly different from previously published data (at 90° flexion). No difference was found in kinematics when comparing CR and PS TKA component designs. Our results suggest that intact extensor mechanisms may be required to perform proper kinematic studies of TKA. Our findings provide evidence that the extensor mechanism may play a major role in the flexion-extension gaps in cadaveric knees. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:627-632, 2014. [ABSTRACT FROM AUTHOR]

This study investigates the roles of orthopedic biomaterial particles [Ti-alloy, poly(methyl methacrylate) (PMMA), ultrahigh-molecular-weight polyethylene (UHMWPE), Co-Cr alloy] on the differentiation and functions of bone marrow stromal cells (BMSCs). Cells were isolated from femurs of BALB/c mice and cultured in complete osteoblast-induction medium in presence of micron-sized biomaterial particles at various doses. 3-(4,5)-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and lactate dehydrogenase assay were performed for cell proliferation and cytotoxicity. Differentiation and function of osteoblasts were evaluated by alkaline phosphatase (ALP), osteocalcin, RANKL, OSX, and Runx2 expressions. Murine interleukin-1 (IL-1), IL-6, and tumor necrosis factor-α in culture media were determined by enzyme-linked immunosorbent assay. Challenge with low doses of Ti, UHMWPE, or Co-Cr particles markedly promoted the bone marrow cell proliferation while high dose of Co-Cr significantly inhibited cell growth ( p < 0.05). Cells challenged with low dose of PMMA or UHMWPE particles (0.63 mg/mL) exhibited strong ALP activity, whereas Ti and Co-Cr groups showed minimal effects ( p < 0.05). UHMWPE and Ti particles also promoted higher expression of proinflammatory cytokines. Real-time polymerase chain reaction data suggested that cells treated with low dose (0.5 mg/mL) particles resulted in distinctly diminished RANKL expression compared to those exposed to high concentrated (3 mg/mL) particles. In conclusion, various types of wear debris particles behaved differently in the differentiation, maturation, and functions of osteogenic cells; and the particulate debris-interacted BMSCs may play an important role in the pathogenesis and process of the debris-associated aseptic prosthetic loosening. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 101A: 2817-2825, 2013. [ABSTRACT FROM AUTHOR]

Poly-ϵ-caprolactone (PCL) is a biodegradable polyester that has received great attentions in clinical and biomedical applications as sutures, drug delivery tool, and implantable scaffoldmaterial. Silica aerogel is amaterial composed of SiO2that has excellent physical properties for use in drug release formulations and biomaterials for tissue engineering. The current study addresses a composite of silica aerogel with PCL as a potential bone scaffold material for bone tissue engineering. The biocompatibility evaluation of this composite indicates that the presence of silica aerogel effectively prevented any cytotoxic effects of the PCL membrane during extended tissue culture periods and improved the survival, attachment, and growth of 3T3 cells and primary mouse osteoblastic cells. The beneficial effect of silica aerogelmay be due to neutralization of the acidic condition that develops during PCL degradation. Specifically, it appears that silica aerogel to PCL wt/wt ratio at 0.5 : 1 maintains a constant pH environment for up to 4 weeks and provides a better environment for cell growth. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate and compare the biocompatibility profiles of hyaluronic acid (HA) viscosupplements from avian and non-mammalian sources. Inflammatory and immune reactions were assessed in models of both clinically relevant and stringent immunological exposure conditions. Experiments were conducted to evaluate tissue reactions and immunological responses and assess antibody formation with the capacity to bind directly to and cross-react with the different viscosupplements. Mice were exposed to viscosupplements using the air pouch inflammation model and specific immunization using Freund's complete adjuvant (FCA). Murine pouch membrane tissue reactions revealed generally mild to moderate responses, with cellular infiltration and cytokine profiles of pouch tissue characteristic of predominantly fibroblastic responses rather than marked inflammatory reactions. In vitro testing indicated that pouch injections did not elicit detectable T-cell proliferative responses, while antibody assays revealed that mice immunized with viscosupplements in FCA and subsequently boosted were capable of mounting an antibody response with a range of specificities. High reactivity to avian serum albumin was seen in sera from mice injected with HA from an avian source, while low positive reactivity to the bacterial antigen Staphylococcal Lipotechoic Acid was observed in sera from mice injected with HA from bacterial sources. These specificities did not indicate any propensity to cross-react, suggesting that patients with adverse immune responses to HA from an avian source should be unresponsive to subsequent injection with HA from a non-avian source. Overall, the findings demonstrate that viscosupplements exhibit good biocompatibility profiles in the murine air pouch, but when provoked to elicit immunological reactions exhibit unique antigenic spectra. These findings suggest that an immunologically mediated immune reaction directed against avian proteins should not necessarily be a contraindication for the administration of non-avian viscosupplements. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012. [ABSTRACT FROM AUTHOR]

We investigated the interactions of particulate PMMA or titanium alloy, patient blood monocytes, and periprosthetic tissues using a SCID-hu model of aseptic loosening. Periprosthetic tissues and bone chips obtained at revision surgery for loosening were transplanted into muscles of SCID mice. Peripheral blood monocytes (PBMCs) isolated from the same donors were fluorescently labeled and co-cultured with PMMA or Ti-6Al-4V particles before intraperitoneal injection. Control mice with periprosthetic tissue or non-inflammatory ligament xenografts received naive PBMCs transfusion. Mice were euthanized 2 weeks after PBMC transfusion. The human tissues were well accepted in SCID mice. Transfused fluorescent-labeled PBMCs were markedly accumulated in transplanted periprosthetic tissues. Multinucleated osteoclast-like cells were commonly seen within retrieved xenograft tissue, and focal bone erosions were ubiquitous. Total cell densities and CD68+ cells within the xenograft were significantly increased in mice transfused with PMMA and Ti-provoked PBMCs compared to the naïve PBMC animals ( p < 0.05). Immunohistochemical staining identified much stronger positive IL-1 and TNF stains in xenografts from either PMMA or Ti-stimulated monocytes transfusion groups ( p < 0.05). TRAP+ cells were found around bone chips in both activated-PBMCs groups, although markedly more aggregated TRAP+ cells in the PMMA-challenged group than in the titanium group ( p < 0.05). MicroCT assessment confirmed the significant decrease of bone mineral density in chips interacted with activated-monocytes/osteoclasts. In conclusion, PMMA or titanium particles readily activate peripheral monocytes and promote the cell trafficking to the debris-containing prosthetic tissues. Particles-provoked PBMCs participated in and promoted the local inflammatory process, osteoclastogenesis, and bone resorption. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:781-786, 2011 [ABSTRACT FROM AUTHOR]

The influence of variant pore‐size and porosity on the microstructure and the mechanical properties of poly‐ε‐caprolactone (PCL) and hydroxyapatite (HA) composite were examined for an optimal scaffold in bone tissue engineering. Three various amounts of sodium chloride (NaCl, as porogens) with two distinct particle size ranges (212–355 μm and 355–600 μm) were blended into PCL and HA mixture, followed by a leaching technique to generate PCL‐HA scaffolds with various pores and porosity. The porosities of the scaffolds were correlated with the porogen size and concentration. The morphological properties of the resulting scaffolds were assessed by micro‐computerized tomography (μCT), scanning electron microscopy (SEM), and energy dispersive X‐ray analysis (EDX). Extensive PCL‐HA pore interconnections with thinner pore walls were present in scaffolds with higher concentration (4:1 w/w) and larger particulate of porogen used in the fabrication process. Embedding of HA particles in the scaffold resulted in rough surfaces on the composites. Instron actuator testing indicated that the tensile strengths and Young's moduli of scaffolds were influenced by both the porosities and pore sizes of the scaffold. It was apparent that increasing the concentration of porogen compromised the mechanical properties; and a larger porogen particle size led to increased tensile strength but a reduction in Young's modulus. Overall, the data indicated that modification of the concentration and particle size of porogen altered the porous features and mechanical strength of HA‐PCL scaffolds. This provided means to manipulate the properties of biocompatible cell‐supporting scaffolds for use as bone graft substitutes. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [ABSTRACT FROM AUTHOR]

In addition to a biocompatible scaffold and an osteogenic cell population, tissue-engineered bone requires an appropriate vascular bed to overcome the obstacle of nutrient and oxygen transport in the 3D structure. We hypothesized that the addition of endothelial cells (ECs) may improve osteogenesis and prevent necrosis of engineered bone via effective neovascularization. Osteoblasts and ECs were differentiated from bone marrow of BALB/c mice, and their phenotypes were confirmed prior to implantation. Cylindrical porous polycaprolactone (PCL)-hydroxyapatite (HA) scaffolds were synthesized. ECs were seeded on scaffolds followed by seeding of osteoblasts in the EC-OB group. In the OB group, scaffolds were only seeded with osteoblasts. The cell-free scaffolds were denoted as control group. A 0.4-cm-long segmental femur defect was established and replaced with the grafts. The grafts were evaluated histologically at 6 weeks postimplantation. In comparison with the OB group, the EC-OB group resulted in a widely distributed capillary network, osteoid generated by osteoblasts and absent ischemic necroses. Pre-seeding scaffold with ECs effectively promoted neovascularization in grafts, prevented the ischemic necrosis, and improved osteogenesis. The integration of bone marrow-derived ECs and osteoblasts in porous scaffold is a useful strategy to achieve engineered bone. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:1147-1152, 2008 [ABSTRACT FROM AUTHOR]

We examined a novel mouse model of wear debris-induced prosthesis instability and osteolysis, and its application for the evaluation of therapy. A stainless steel or titanium-alloy pin was implanted into the proximal tibia to form a contiguous surface with the articular cartilage. In some mice, titanium particles were injected into the tibial canal during the surgery, followed by monthly intraarticular injection. MicroCT scans revealed that the implants without particle challenge were stable without bone mineral density changes for 6 months. Histological analysis showed new bone formation around the implant at 6 weeks postsurgery. Periprosthetic soft tissue with inflammatory cells was a ubiquitous finding at the interface between the implant and surrounding bone in samples exposed to titanium particles, and expression of IL-1β, TNFα, and CD68 was common in these joints. Pullout tests indicated that an average 5N load was required to pull out stable implants from surrounding bone. However, particle stimulation dramatically reduced the pullout force to less than 0.4 N. The feasibility of in vivo gene transfer on this model was confirmed by X-gal staining of synovial membrane and periprosthetic tissue after injection of AAV-LacZ in the prosthetic joint. This murine model of weight-bearing knee prosthesis provides an economical, reproducible, and easily obtained means to study joint arthroplasty failure. The ability to evaluate the biomechanical properties of the prosthetic joint, in addition to histological and biochemical examination, results in a useful model to investigate many of the properties of prosthetic joint components during the response to debris-associated osteolysis. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:603-611, 2007 [ABSTRACT FROM AUTHOR]

A murine model of osteosarcoma was developed to investigate the association between the expression of VEGF and the progression of osteosarcoma. Two human osteosarcoma cell lines with distinct VEGF expressions were introduced into proximal tibiae of immuno-deficient SCID mice, either by direct injection through the cortical bone or surgical exposing and drilling on the tibial metaphysis to seed tumor cells. Bone tumors were obvious on microCT within 4 weeks following osteosarcoma cell inoculation through surgical delivery. In contrast, direct injection without drilling often resulted in periosteal tumors. Although neoplasms were developed regardless of VEGF levels, orthotopic tumors derived from high VEGF-expressing cells were detected 2 weeks earlier on CT images than the ones from VEGF negative cells. At sacrifice, high VEGF tumors were distinctively larger in size and more frequently invaded the adjacent bone tissue. Multiple metastatic lesions were found in all the lung tissues at 8 weeks from high VEGF group, whereas only 1 of 7 VEGF negative tumors exhibited pulmonary metastasis. Overall, this model developed with the surgical tumor cell delivery results in histological and radiographic features more consistent with primary osteosarcoma. Interestingly, VEGF expression correlates with the early establishment, rapid tumor growth, and the development of pulmonary metastasis. [ABSTRACT FROM AUTHOR]

Signaling of RANK (receptor activator of nuclear factor kappa B) through its ligand RANKL appears critical in osteolysis associated with aseptic loosening (AL). The purpose of this study was to investigate the role of RANK in a murine osteolysis model developed in RANK knockout (RANK-/-) mice. Ultra high molecular weight polyethylene (UHMWPE) debris was introduced into established air pouches on RANK-/- mice, followed by implantation of calvaria bone from syngeneic littermates. Wild type C57BL/6 (RANK+/+) mice injected with either UHMWPE or saline alone were included in this study. Pouch tissues were collected 14 days after UHMWPE inoculation for molecular and histology analysis. Results showed that UHMWPE stimulation induced strong pouch tissue inflammation in RANK-/- mice, as manifested by inflammatory cellular infiltration, pouch tissue proliferation, and increased gene expression of IL-1β, TNFα, and RANKL. However, the UHMWPE-induced inflammation in RANK-/- mice was not associated with the osteoclastic bone resorption observed in RANK+/+ mice. In RANK+/+ mice subjected to UHMWPE stimulation, a large number of TRAP+ cells were found on the implanted bone surface, where active osteoclastic bone resorption was observed. No TRAP+ cells were found in UHMWPE-containing pouch tissues of RANK-/- mice. Consistent with the lack of osteoclastic activity shown by TRAP staining, no significant UHMWPE particle-induced bone resorption was found in RANK-/- mice. A well preserved bone collagen content (Van Gieson staining) and normal plateau surface contour [microcomputed tomography (µCT)] of implanted bone was observed in RANK-/- mice subjected to UHMWPE stimulation. In conclusion, this study provides the evidence that UHMWPE particles induce strong inflammatory responses, but not associated with osteoclastic bone resorption in RANK-/- mice. This indicates that RANK signaling is essential for UHMWPE particle-induced osteoclastic bone resorption, but does not participate in UHMWPE particle-induced inflammatory response. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 24:1575-1586, 2006 [ABSTRACT FROM AUTHOR]

Up to 20% of patients with total joint arthroplasty will develop radiographic evidence of aseptic loosening (AL), which most likely results from an inflammatory response to billions of wear debris shed from the implant. Our previous work has demonstrated that erythromycin (EM), a macrolide antibiotic, inhibits wear debris-induced inflammatory osteoclastogenesis through the reduction of cytokine production and osteoclast differentiation, both of which involve the NF-κB pathway. The aim of the current study was to determine whether EM inhibits wear debris-induced inflammatory osteolysis in a murine osteolysis model. Ultrahigh molecular-weight polyethylene (UHMWPE) debris was introduced into established air pouches on BALB/c mice, followed by implantation of calvaria bone from syngeneic littermates. EM (2 mg/kg/day) was given to mice intraperitoneally 2 days before UHMWPE introduction and maintained until the sacrifice of the mice. Mice with and without EM treatment, as well as control mice injected with saline alone were included in this study. Pouch tissues were collected 14 days after UHMWPE inoculation for molecular and histology analysis. Our findings indicate that: (1) EM reduced UHMWPE-induced tissue inflammation, including the diminished pouch membrane thickness, reduced inflammatory cellular infiltration, and lowered IL-1β and TNF-α expression (mRNA and protein); (2) EM inhibited UHMWPE-induced osteoclastogenesis, with reduced gene activation of RANK, RANKL, and CPK, and diminished RANKL expression in UHMWPE stimulated pouches, and (3) EM markedly reduced the number of TRAP+ cells in pouch tissues, and protected against bone collagen depletion. In conclusion, this study provides the evidence that EM inhibits the UHMWPE particles-induced inflammatory osteolysis in a murine model, and represents a promising therapeutic candidate for the prevention and treatment of AL. © 2005 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res [ABSTRACT FROM AUTHOR]

Abstract: The significance of an immune response in complications of bone allograft procedures is not well understood. This study evaluates the immunological reaction to bone allografts in either cortical or cancellous form. Serological responses from osteoarthritis (OA) patients and normal individuals to soluble proteins extracted from allografts were assessed using Western blotting and ELISA techniques. A large number of patients expressed antibodies to bone proteins extracted from the washed bone as compared with normal controls. Antibodies were present in patients without the use of bone allografts, indicating that OA patients develop antibodies to bone soluble proteins. However, patients receiving allografts exhibited an increased immune reactivity against multiple bone proteins when compared with non-grafted patients. Protein characterization of the immunoreactive proteins revealed that the majority of antigenic targets were fragments of various collagen molecules. The data suggests that OA patients develop antibodies to bone soluble proteins prior to surgery, and these antibodies increase after revision surgery utilizing bone allografts. These findings support the implications that various collagen molecules as well as their degraded fragments represent potential immunogenic proteins within bone allografts. The removal of these antigenic proteins from the allografts prior to surgery may alleviate this immunological reactivity and improve graft outcome. [Copyright &y& Elsevier]

Activation of nuclear factor kappa B (NF-κB) signaling in response to cell stimulation by wear debris may be critical in the pathogenesis of aseptic loosening. Erythromycin (EM), a macrolide antibiotic, has been shown to effectively suppress some types of inflammatory reactions. In this study, we examined the effect of EM on wear debris-induced osteoclastic bone resorption in vitro. EM inhibited Ca+ release from neonatal calvaria co-cultured with conditioned medium from mouse RAW264.7 macrophages activated by wear debris. Inhibition of Ca+ release was associated with a decreased number of tartrate-resistant acid phosphatase (TRAP)-positive cells in cultured bones. To investigate the mechanism whereby EM inhibits bone-resorption, RAW cells were incubated with wear debris in the presence EM. Real time RT-CR analysis revealed that EM (5 μg/ml) significantly inhibited mRNA expression of NF-κB, cathepsin K (CPK), IL-1β and TNFα, but not RANK in RAW cells stimulated with wear debris. Furthermore, electrophoretic mobility-shift assay showed that EM (0.2 μg–5 μg/ml) could reduce DNA-binding activity of NF-κB in RAW cells stimulated with wear debris. The inhibition of inflammatory osteoclastogenesis by EM treatment was further confirmed by an osteoclast (OC) formation assay using primary cultures of mouse bone marrow progenitor cells stimulated with macrophage colony-stimulating factor and RANK ligand (RANKL). EM treatment (5 μg/ml) resulted in more than 70% reduction in multinucleated OC formation and 50% reduction of TRAP+ cells by bone marrow progenitor cells. Our findings support that EM suppresses wear debris-induced osteoclastic bone resorption by, at least, down-regulation of NF-κB signaling pathway. It appears that EM represents a potential therapeutic candidate for the treatment and prevention of aseptic loosening. [Copyright &y& Elsevier]

There is considerable evidence that orthopaedic wear debris plays a crucial role in the pathology of aseptic loosening of joint prostheses. This study examined the effect of inflammatory membranes stimulated with methyl methacrylate and polyethylene on bone resorption, using the murine air pouch model. The capacity of RAW 264.7 mouse macrophages exposed to polymer particles to produce factors affecting bone metabolism was also studied. Neonatal calvaria bones were co-cultured with either pouch membranes or conditioned media from activated macrophages. Bone resorption was measured by the release of calcium from cultured bones, and the activity of tartrate-resistant acid phosphatase in both bone sections and culture medium was also assayed. Results showed that inflammatory pouch membrane activated by methyl methacrylate and polyethylene enhanced osteoclastic bone resorption. Conditioned media from particles stimulated mouse macrophages also stimulated bone resorption, although this effect was weaker than resorption induced by inflammatory pouch membranes. The addition of the particles directly into the medium of cultured calvaria bones had little effect on bone resorption. Our observations indicate that both inflammatory tissue and macrophages provoked by particles can stimulate bone resorption in cultured mouse neonatal calvaria bones. This simple in vitro bone resorption system allows us to investigate the fundamental cellular and molecular mechanism of wear debris induced bone resorption and to screen potential therapeutic approaches for aseptic loosening. [Copyright &y& Elsevier]

Objective: Following the demonstration that the stress protein, BiP, prevented induction of collagen-induced arthritis (CIA) in HLA-DRB*0101+/+ (HLA-DR1+/+) mice, we investigated the immunotherapeutic ability of BiP to suppress disease during the active phase of CIA in HLA-DR1+/+ and DBA/1 mice., Methods: BiP was administered either subcutaneously or intravenously to DBA/1, HLA-DR1+/+, or interleukin-4 (IL-4)-knockout mice at the onset of arthritis. Immune cells were used in adoptive transfer studies or were restimulated in culture with BiP or type II collagen (CII). Proliferation and cytokine release were measured. In addition, serum anti-CII antibodies were measured by enzyme-linked immunosorbent assay. Disease progression was scored using a visual analog scale., Results: BiP was successful in suppressing established CIA in HLA-DR1+/+ and DBA/1 mice. Serum levels of anticollagen IgG antibodies were reduced in BiP-treated mice. T cells from BiP-immunized mice produced Th2 cytokines, in particular, IL-4. Treatment with BiP was also shown to increase the production of CII-specific IL-5, IL-10, and interferon-gamma at the termination of the study. Development of severe CIA was prevented by the intravenous transfer of BiP-specific cells at the time of CIA induction in HLA-DR1+/+ mice or by transferring BiP-specific cells to DBA/1 mice at the onset of disease. BiP failed to ameliorate the development of CIA in IL-4-/-, HLA-DR1+/+ mice., Conclusion: These novel results show that BiP can suppress active CIA by the induction of regulatory cells that act predominantly via IL-4. Thus, BiP is a potential immunotherapeutic agent for the treatment of patients with rheumatoid arthritis.

Objective: To develop a passively targeted, patient-compliant, intranasal interleukin-10 (IL-10) gene therapy delivery system and to investigate its therapeutic benefit in experimental collagen-induced arthritis, a model of rheumatoid arthritis., Methods: Arthritis was induced in DBA/1 mice and monitored following intranasal administration of an IL-10 plasmid (pG-IL-10) or the empty vector 2 days (days -2 and 19) prior to collagen injection (prophylactic group, as a single dose after collagen boost on day 21 (early therapy group, or as a single dose upon acquisition of a disease score of 3 (late therapy group. IL-10-induced alterations in cytokine secretion and proliferation by spleen and lymph node cells were assessed on days 31 and 65 and correlated with histologic changes and bone erosions assessed on day 65., Results: Intranasal delivery of pG-IL-10 significantly delayed arthritis onset and reduced disease severity in the prophylactic group and early therapy group, reduced cellular infiltration and bone loss in the early therapy group, and reduced T cell proliferation in response to collagen on days 31 and 65 in these two groups, with a significant reduction in tumor necrosis factor alpha production on day 65. Within the late therapy group, disease progression was arrested for the rest of the study. The intranasally administered pG-IL-10 targeted monocytes and macrophages and showed dissemination to inflamed joints and draining lymph nodes in vivo. Importantly, systemic levels of IL-10 (in serum) were transient (peaking on day 2) and undetectable by day 4., Conclusion: Intranasal IL-10 gene delivery significantly reduces bone destruction, shows evidence of reducing joint inflammation, and may be mediated by high local levels of IL-10 produced by transfected monocytes trafficking to inflamed joints and draining lymph nodes.

Objective: To characterize chronic murine pristane-induced arthritis (PIA) with regard to the response to antirheumatic agents, expression levels of proinflammatory cytokines, and immunopathologic features., Methods: Male DBA/1 mice were injected intraperitoneally with pristane oil to induce a chronic polyarthritis, which was monitored by visual scoring. Serum antibody and splenocyte responses to a panel of putative joint-derived autoantigens were measured. Whole paws were evaluated postmortem for changes in the levels of proinflammatory cytokines tumor necrosis factor alpha (TNFalpha), interleukin-1beta (IL-1beta), and IL-6 by enzyme-linked immunosorbent assay, and standard histopathology techniques were used to determine joint structural changes. Therapeutic studies were performed for up to 8 weeks of dosing with prednisolone, methotrexate, 3 nonsteroidal antiinflammatory drugs (celecoxib, diclofenac, and indomethacin), a p38 MAPK inhibitor, SB242235, and human soluble TNF receptor (sTNFR; etanercept) and murine sTNFR fusion proteins., Results: Antibody and cellular responses to the putative joint autoantigens revealed a broad extent of autoimmunity in PIA. TNFalpha, IL-1beta, and IL-6 were all persistently up-regulated in PIA joints. Prednisolone, methotrexate, celecoxib, indomethacin, and SB242235 all significantly reduced the arthritis scores. Etanercept was ineffective in reducing the arthritis scores, whereas murine sTNFR produced a significant, but nonsustained, benefit. Only prednisolone significantly reduced the expression of TNFalpha, IL-1beta, and IL-6 in the joints. Prednisolone and methotrexate demonstrated the most effective joint protection., Conclusion: We have markedly extended the characterization of PIA as a murine model of chronic inflammatory arthritis by demonstrating cellular and humoral autoantigenicity, elevation of clinically precedented joint cytokines, and variation in the response to several antirheumatic therapies. PIA offers significant potential for the long-term study of immunopathologic mechanisms and novel therapies in rheumatoid arthritis., (Copyright 2004 American College of Rheumatology)