Adeno-associated virus-mediated osteoprotegerin gene transfer protects against particulate polyethylene-induced osteolysis in a murine model. (57/642)

OBJECTIVE: Osteoprotegerin (OPG), a natural negative regulator of osteoclastogenesis and bone resorption, may be a potential therapeutic agent for treatment of osteolysis-associated prosthetic joint loosening. Using an in vivo adeno-associated virus (AAV)-mediated gene transfer technique, this study was designed to evaluate the protective effects of OPG transgene against orthopedic wear debris-induced bone loss in a murine model of osteolysis. METHODS: Bone tissue was implanted into established pouches on BALB/c mice, followed by the introduction of ultra-high-molecular-weight polyethylene (UHMWPE) particles to provoke inflammation and osteolysis. The viruses encoding human OPG gene (rAAV-hOPG) or beta-galactosidase marker gene (rAAV-LacZ) were injected into the air pouches, and the tissue was harvested 7 days after viral infection for histologic and molecular analyses. RESULTS: Successful transgene expression was confirmed by the detection of OPG by enzyme-linked immunosorbent assay and positive X-Gal staining of pouch tissue (LacZ). Real-time polymerase chain reaction indicated significant diminishment of messenger RNA expression of osteoclast markers in OPG-transduced pouches compared with rAAV-LacZ-transduced pouches. The transduction and expression of OPG also markedly decreased the gene copies of the biologic receptor activator of nuclear factor kappaB. The expression of OPG in the bone-implanted pouch reduced bone calcium release by a mean of 39% compared with the calcium release in the other 2 groups. Computerized image analysis revealed that expression of OPG significantly protected against bone collagen loss. CONCLUSION: OPG gene transfer mediated by rAAV effectively protects against particulate polyethylene-induced bone resorption in this experimental model. Data suggest that gene transfer using rAAV-OPG may be a feasible and effective therapeutic candidate to treat or prevent wear debris-associated osteolysis and aseptic loosening.  (+info)

Clonotypic myeloma cells able to xenograft myeloma to nonobese diabetic severe combined immunodeficient mice copurify with CD34 (+) hematopoietic progenitors. (58/642)

The identity of the multiple myeloma (MM) precursor(s) is unknown. Our objective was to determine the myelomagenic capabilities of CD34-enriched autografts. Hematopoietic progenitor fractions from fresh or cryopreserved granulocyte-colony-stimulating factor mobilized blood from myeloma patients were obtained by sorting or enrichment, followed by RT-PCR analysis of clonotypic transcripts and/or their ability to transfer myeloma to immunodeficient mice. CD34(+) enrichment using immunomagnetic methods comparable with those used clinically results in copurification of MM cells able to xenograft nonobese diabetic severe combined immunodeficient mice. Highly purified CD34(+) progenitors from granulocyte-colony-stimulating factor mobilized blood of myeloma patients include, on average, 31% clonotypic MM cells. CD34(+) progenitors also include 31% DNA aneuploid cells. For six of six MM patients, enriched progenitors were myelomagenic as measured by engraftment of clonotypic cells and/or the development of lytic bone lesions. Intrasternal injection of enriched progenitor fractions led to clonotypic cells in the femoral bone marrow and bone lesions at distant skeletal locations, confirming dissemination of myelomagenic cells. MM precursors copurify with normal hematopoietic progenitors, emphasizing the need for tumor-free grafts. Autologous MM engraftment is likely to be considerably more efficient than in a xenogeneic host, strongly suggesting that MM autografts contribute to posttransplant relapse. The xenografting myelomagenic component(s) is unlikely to be plasma cells, given the lack of morphologically identified plasma cells among enriched progenitors. Xenografting MM precursors appear to be CD34(+)CD45(low), similar to normal progenitors. Precursor function within the MM clone seems to be complex and may involve multiple components of the MM hierarchy.  (+info)

The influence of biomaterial on patterns of failure after cemented total hip replacement. (59/642)

We examined aseptic loosening and osteolysis in 77 revised McKee-Arden total hip arthroplasties (THAs) using polyethylene cups and identical femoral stems made from either cobalt chrome alloy or titanium alloy. Time to failure was significantly shorter in the titanium group. Loosening and peri-prosthetic osteolysis occurred with significantly higher frequency in the titanium group compared to the cobalt chrome group.  (+info)

Human myeloma cells stimulate the receptor activator of nuclear factor-kappa B ligand (RANKL) in T lymphocytes: a potential role in multiple myeloma bone disease. (60/642)

The biologic mechanisms involved in the pathogenesis of multiple myeloma (MM) bone disease are not completely understood. Recent evidence suggests that T cells may regulate bone resorption through the cross-talk between the critical osteoclastogenetic factor, receptor activator of nuclear factor-kappaB ligand (RANKL), and interferon gamma (IFN-gamma) that strongly suppresses osteoclastogenesis. Using a coculture transwell system we found that human myeloma cell lines (HMCLs) increased the expression and secretion of RANKL in activated T lymphocytes and similarly purified MM cells stimulated RANKL production in autologous T lymphocytes. In addition, either anti-interleukin 6 (anti-IL-6) or anti-IL-7 antibody inhibited HMCL-induced RANKL overexpression. Consistently, we demonstrated that HMCLs and fresh MM cells express IL-7 mRNA and secrete IL-7 in the presence of IL-6 and that bone marrow (BM) IL-7 levels were significantly higher in patients with MM. Moreover, we found that the release of IFN-gamma by T lymphocytes was reduced in presence of both HMCLs and purified MM cells. Furthermore, in a stromal cell-free system, osteoclastogenesis was stimulated by conditioned medium of T cells cocultured with HMCLs and inhibited by recombinant human osteoprotegerin (OPG; 100 ng/mL to 1 microg/mL). Finally, RANKL mRNA was up-regulated in BM T lymphocytes of MM patients with severe osteolytic lesions, suggesting that T cells could be involved at least in part in MM-induced osteolysis through the RANKL overexpression.  (+info)

Guanosine nucleotides inhibit different syndromes of PTHrP excess caused by human cancers in vivo. (61/642)

There are two well-described syndromes caused by tumor production of parathyroid hormone-related peptide (PTHrP), namely osteolytic bone disease associated with breast cancer and humoral hypercalcemia of malignancy (HHM) that occurs with or without bone metastasis. Both syndromes have been shown experimentally to be inhibited by neutralizing antibodies to PTHrP. In a search for small-molecule inhibitors of PTHrP production or effects, we have identified guanine-nucleotide analogs as compounds that inhibit PTHrP expression by human tumor cells associated with these syndromes. We show in nude athymic murine models that these compounds reduce PTHrP-mediated osteolytic lesions associated with metastatic human breast-cancer cells as well as the degree of hypercalcemia caused by excessive PTHrP production by a squamous-cell carcinoma of the lung. These results suggest that the PTHrP gene promoter may be a suitable target for treating the skeletal effects of malignancy.  (+info)

Relative accretion of 99mTc-polyphosphate by forming and resorbing bone systems in rats: its significance in the pathologic basis of bone scanning. (62/642)

The relative roles of osteogenesis andd osteolysis in the production of positive radionuclide images of skeletal lesions were investigated. The uptake of 99mTc-polyphosphate (Tc-PP) by each process was measured in an animal model that permitted bone formation and resorption to be studied independently. Ten rats received intramuscular implants of bone-forming demineralized matrix (DM) and resorbing devitalized bone (DV). Radiographs and Tc-PP scintiscans were made each week thereafter. At 6-10 weeks, the implants and normal bone samples were removed, counted for 99mTc, and examined histologically. The uptake of Tc-PP BY DM implants was first detected on images made 3 weeks after implanatation, and by DV implants, 1-2 weeks later. Serial radiography showed progressive calcification of DM an resorption of DV implants. Microscopic examinations of undecalcified sections, stained with a modified Goldner preparation, revealed vital-bone formation in the DM implants and osteoclastic resorption in the DV. Activity counts per gram of DM and DV implants were, respectively, 200% and 90% that of normal bone. Since only the bone-forming system (DM) accumulated Tc-PP at greater than normal concentrations, this study indicates that positive bone images of osteolytic lesions solely reflect compensatory osteogenic responses.  (+info)

Macrophage inflammatory protein 1-alpha (MIP-1 alpha ) triggers migration and signaling cascades mediating survival and proliferation in multiple myeloma (MM) cells. (63/642)

Recently, it has been demonstrated that macrophage inflammatory protein 1- alpha (MIP-1 alpha) is crucially involved in the development of osteolytic bone lesions in multiple myeloma (MM). The current study was designed to determine the direct effects of MIP-1 alpha on MM cells. Thus, we were able to demonstrate that MIP-1 alpha acts as a potent growth, survival, and chemotactic factor in MM cells. MIP-1 alpha-induced signaling involved activation of the AKT/protein kinase B (PKB) and the mitogen-activated protein kinase (MAPK) pathway. In addition, inhibition of AKT activation by phosphatidylinositol 3- kinase (PI3-K) inhibitors did not influence MAPK activation, suggesting that there is no cross talk between MIP-1 alpha-dependent activation of the PI3-K/AKT and extracellular-regulated kinase (ERK) pathway. Our data suggest that besides its role in development of osteolytic bone destruction, MIP-1 alpha also directly affects cell signaling pathways mediating growth, survival, and migration in MM cells and provide evidence that MIP-1 alpha might play a pivotal role in the pathogenesis of MM.  (+info)

Receptor activator of NF-kappaB ligand, macrophage inflammatory protein-1alpha, and the proteasome: novel therapeutic targets in myeloma. (64/642)

BACKGROUND: The bone destruction in myeloma patients is largely responsible for the clinical features of the disease. However, only recently has attention focused on identifying and developing drugs targeted specifically at the osteolysis. Receptor activator of NF-kappaB ligand (RANKL), macrophage inflammatory protein (MIP)-1alpha, and proteasomal function have been implicated in the pathogenesis of myeloma and associated bone disease. We provide "proof of principle" in preclinical myeloma models that these are indeed valid molecular targets in development of novel therapeutics. METHODS: The efficacy of antagonists of RANKL and MIP-1alpha bioactivities (RANK.Fc and neutralizing monoclonal anti-MIP-1alpha antibody) in ameliorating osteolysis and reducing tumor burden was evaluated in a mouse model in which murine myeloma 5TGM1 cells are injected intravenously into syngeneic mice. In addition, the activity of a petidyl aldehyde proteasome inhibitor (proteasome inhibitor-1 [PSI]) on tumor growth was tested in a murine 5TGM1 plasmacytoma model and in mice intravenously inoculated with 5TGM1 cells. RESULTS: RANK.Fc and anti-MIP-1alpha antibody inhibited the development and progression of osteolytic lesions and significantly reduced tumor load assessed by serum monoclonal paraprotein titers. Intratumoral injections of PSI inhibited growth of 5TGM1 plasmacytomas and induced tumor regression in some cases. In addition, systemic administration of PSI significantly prolonged time to onset of paraplegia in tumor-bearing mice. CONCLUSIONS: The results highlight the critical roles of RANKL and MIP-1alpha in the development and progression of myeloma and provide a basis for future evaluation in myeloma patients of novel therapeutics that disrupt interactions of RANKL and MIP-1alpha with their cognate receptors. The data also suggest that further studies in preclincal myeloma models aimed at identifying other proteasome inhibitors with antitumor efficacy would be worthwhile.  (+info)