Objective To observe the expressions of extracellular matrix metalloproteinase inducer (EMMPRIN) and matrix metalloproteinase 9 (MMP-9) around the prosthesis, and to study the relationship between the expressions of EMMPRIN and MMP-9 and osteolysis around prosthesis. Methods Interface tissues were obtained at three Delee-Charnley acetabular sections and seven Gruen femur sections from 8 cases (8 hips) undergoing revision after total hip arthroplasty between February 2010 and January 2012, and were divided into osteolysis group and non-osteolysis group based on preoperative X-ray film and intraoperative observation; the tissues from another 8 patients with osteoarthritis undergoing total hip arthroplasty as the control group. The immunohistochemical staining and RT-PCR assays were used to determine the expressions of EMMPRIN and MMP- 9. The correlation between the positive cells and the severity of osteolysis were analyzed and compared. Results Histological examination showed that many macrophages, multinucleated giant cells assembled in the membrane of osteolysis zone, but many fibroblasts and synovial cells in non-osteolysis zones. EMMPRIN and MMP- 9 positive cells and gene expressions were observed in every group. The percentage of positive cells and gene expression of EMMPRIN and MMP-9 in osteolysis group were significantly higher than those in non-osteolysis and control groups (P lt; 0.05), but no significant difference was found between non-osteolysis group and control group (P gt; 0.05). The percentage of positive cells of EMMPRIN in zone III of acetabular was higher than that in zone I and zone II of revision hip (P lt; 0.05), but no significant difference between zone I and zone II (P gt; 0.05). The percentage of positive cells of MMP-9 in zone I and zone III was significantly higher than that in zone II of revision hip (P lt; 0.05), but no significant difference between zone I and zone III (P gt; 0.05). The expression of EMMPRIN from high to low in order was zones 1, 7, 4, 2, 3, 5, and 6 at femur; the values of zones 1, 7, and 4 were significantly higher than those of zones 2, 3, 5, and 6 (P lt; 0.05), but no significant difference among zones 1, 7, and 4, and among zones 2, 3, 5, and 6 (P gt; 0.05). The expression of MMP-9 from high to low in order was zones 1, 7, 4, 2, 3, 6, and 5 at femur; the values of zones 1 and 7 were significantly higher than those of zones 4, 2, 3, 6, and 5 (P lt; 0.05), and the values of zones 4 and 2 were significantly higher than those of zones 3, 6, and 5 (P lt; 0.05), but no significant difference between zone 1 and zone 7, between zone 4 and zone 2, and among zones 3, 5, and 6 (P gt; 0.05). Conclusion The expressions of EMMPRIN and MMP-9 have certain coherence. The over-expressions of EMMPRIN and MMP-9 may be one of the key points of inhibiting bone reconstruction and bone resorption at bone-implant interface under the stimulation of wear debris．
Objective To observe the effect of local injection of vascular endothel ial growth factor (VEGF) and VEGF antibody on the wear particle-induced osteolysis in the mouse air pouch model and to investigate the role of VEGF in the process of aseptic loosening of prosthesis. Methods The stem of metal hip prosthesis was obtained from the revision surgery.Metallic wear particles were made by vacuum ball mill ing. Wear particles suspension was prepared into the concentration of 10 mg/mL with PBS. Fifty female Kunming mice (aged 8-10 weeks, weighing about 25 g) were selected. Of 50 mice, 10 were used as the donors of bone graft, the other 40 were equally divided into control group (group A), particle group (group B), VEGF group (group C), and VEGF inhibited group (group D). Air pouches were made on the back of 40 mice by injecting sterile air subcutaneously. At 8th day, a graft of calvaria from the donor mice was implanted in air pouch. In groups B, C, and D, 0.5 mL wear particles suspension was injected into the air pouches, and in group A, 0.5 mL PBS was injected. Once a day at 6th and 7th days during the air pouch preparation and one time every two days after bone implantation, 0.2 mL recombinant human VEGF (rhVEGF) and VEGF antibody (Bevacizumab) were injected into the air pouches in groups C and D, respectively. In group A and group B, 0.2 mL sal ine was injected. Pouch tissues and bone were harvested at 2 weeks after bone implantation for HE staining, real-time fluorescent quantitative PCR and ELISA analyses. Results All mice survived to the end of experiment. The gross observation showed that there were mild redness, swell ing, and less neovascularization in air pouches in group A. There were obvious redness, swell ing, and more exudative and neovascularization in groups B, C, and D, most obvious in group C, the next in group B, then in group D. The histological and molecular biological analysis showed that inflammatory responses and osteolysis were obvious in group B and the pouch membrane thickness, the cell density, transforming growth factor α, interleukin 1β, and VEGF were significantly higher than those in group A (P lt; 0.05). The inflammatory responses and osteolysis were mostobvious in group C and the above-mentioned indexes were significantly higher than those in group B (P lt; 0.05). There were some inflammatory responses and osteolysis in group D, but the indexes were significantly lower than those in group B (P lt; 0.05) and were significantly higher than those in group A (P lt; 0.05). Conclusion VEGF can promote inflammatory responses and osteolysis in aseptic loosening of prosthesis. VEGF antibody can effectively inhibit wear particle-induced osteolysis.
Objective To evaluate the mechanisms of p42/p44 kinase phosphorylation in cell models and to investigate the effect of simvastatin on the prevention and treatment of aseptic loosening of prosthesis by observing the influence of simvastatin on the levels of tumor necrosis factor α (TNF-α) and monocyte chemoattractant protein 1 (MCP-1) of human peri pheral blood mononuclear cell (PBMC) challenged with titanium particles. Methods PBMC from 45 mL peripheral blood of healthy adult voluntary donators, were separated and cultured, and divided into 5 groups according to different culturemedium: group A, PBMC and titanium particles; group B, PBMC and titanium particles with 1 × 10-5 mol/L simvastatin; group C, PBMC and titanium particles with 1 × 10-6 mol/L simvastatin; group D, PBMC and titanium particles with 1 × 10-7 mol/L simvastatin; and group E, PBMC and titanium particles with the extracellular signal-regulated kinase (ERK1/2) inhibitor U0126. The contents of TNF-α and MCP-1 were tested by ELISA after 24 hours of culture. PBMC were pretreated with different medium grouping as groups A, B, C, D, and E for 60 minutes, and were challenged with titanium particles for 30 minutes and 60 minutes, then the level of ERK1/2 expression was tested by Western blot. Results In groups A, B, C, D, and E, the absorbance (A) values of TNF-α were 1.115 5 ± 0.243 6, 0.693 6 ± 0.354 3, 0.695 7 ± 0.387 3, 0.716 4 ± 0.478 9, and 0.263 5 ± 0.101 6, respectively; and the A values of MCP-1 were 1.421 0 ± 0.105 3, 0.915 1 ± 0.411 3, 1.003 5 ± 0.464 2, 1.102 0 ± 0.353 9, and 0.271 3 ± 0.145 1, respectively. The levels of TNF-α and MCP-1 in group A were significantly higher than others, showing significant differences (P lt; 0.05). There were significant differences between group E and groups B, C, and D (P lt; 0.05), between group B and groups C, D (P lt; 0.05); no significant difference between group C and group D (P gt; 0.05). Western blot results showed the expression of ERK1/2 in all groups at 30 minutes and 60 minutes of culture. The levels of ERK1/2 expression were 1.612 1 ± 0.068 2, 1.078 1 ± 0.072 8, 1.268 7 ± 0.223 1, 1.439 7 ± 0.180 1, and 0.732 0 ± 0.110 4 in groups A, B, C, D, and E, respectively; showing significant differences between groups (P lt; 0.05). Conclusion ERK1/2 is a phosphorylated protein after stimulated by wear particles; it is also one of the most important cell signal ing activation of macrophage. Simvastatin can inhibit the expression of bone absorptive factors induced by wear particles and may be used in the prevention and treatment of aseptic loosening of prosthesis.