BMPs in periprosthetic tissues around aseptically loosened total hip implants

Background and purpose

Primary and dynamically maintained periprosthetic bone formation is essential for osseointegration of hip implants to host bone. Bone morphogenetic proteins (BMPs) play a role in osteoinductive bone formation. We hypothesized that there is an increased local synthesis of BMPs in the synovial membrane-like interface around aseptically loosened total hip replacement (THR) implants, as body attempts to generate or maintain implant fixation.

Patients and methods

We compared synovial membrane-like interface tissue from revised total hip replacements (rTHR, n = 9) to osteoarthritic control synovial membrane samples (OA, n = 11. Avidin-biotin-peroxidase complex staining and grading of BMP-2, BMP-4, BMP-6, and BMP-7 was done. Immunofluorescence staining was used to study BMP proteins produced by mesenchymal stromal/stem cells (MSCs) and osteoblasts.

Results and interpretation

All BMPs studied were present in the synovial lining or lining-like layer, fibroblast-like stromal cells, interstitial macrophage-like cells, and endothelial cells. In OA and rTHR samples, BMP-6 positivity in cells, inducible by the proinflammatory cytokines tumor necrosis factor−α and interleukin-1β, predominated over expression of other BMPs. Macrophage-like cells positive for BMP-4, inducible in macrophages by stimulation with particles, were more frequent around loosened implants than in control OA samples, but apparently not enough to prevent loosening. MSCs contained BMP-2, BMP-4, BMP-6, and BMP-7, but this staining diminished during osteogenesis, suggesting that BMPs are produced by progenitor cells in particular, probably for storage in the bone matrix.     

Increased expression of EMMPRIN in the tissue around loosened hip prostheses

Matrix metalloproteinases (MMPs) have been shown to play a role in aseptic loosening of total hip replacement (THR). Extracellular matrix metallo-proteinase inducer (EMMPRIN) can upregulate expression of several MMPs but has little effect on their tissue inhibitor (TIMP)- Using the avidin-biotin-per-oxidase complex immunostaining method, we detected strong immunoreactivity of EMMPRIN in the lining-like layers, sublining area and vascular endothelium of synovial membrane-like interface tissue around loosened prostheses. In contrast, EMMPRIN staining was very weak in the synovial samples from patients with hip arthrosis. Double immunofluorescence labeling revealed EMMPRIN/MMP-1 double-positive cells in iining-iike layers and the sublining area of interface tissue.

Our findings indicate that EMMPRIN expression is upregulated in interface tissue, and that locally accumulated EMMPRIN may modulate MMP-1 expression. An imbalance in the activity of MMPs and TIMP may lead to tissue destruction and periprosthetic osteolysis. These biological responses, combined with mechanical stress caused by micromotion and oscillating fluid pressure, may eventually cause aseptic loosening of THR.     

Increased expression of EMMPRIN in the tissue around loosened hip prostheses

Matrix metalloproteinases (MMPs) have been shown to play a role in aseptic loosening of total hip replacement (THR). Extracellular matrix metalloproteinase inducer (EMMPRIN) can upregulate expression of several MMPs but has little effect on their tissue inhibitor (TIMP). Using the avidin-biotin-peroxidase complex immunostaining method, we detected strong immunoreactivity of EMMPRIN in the lining-like layers, sublining area and vascular endothelium of synovial membrane-like interface tissue around loosened prostheses. In contrast, EMMPRIN staining was very weak in the synovial samples from patients with hip arthrosis. Double immunofluorescence labeling revealed EMMPRIN/MMP-1 double-positive cells in lining-like layers and the sublining area of interface tissue. Our findings indicate that EMMPRIN expression is upregulated in interface tissue, and that locally accumulated EMMPRIN may modulate MMP-1 expression. An imbalance in the activity of MMPs and TIMP may lead to tissue destruction and periprosthetic osteolysis. These biological responses, combined with mechanical stress caused by micromotion and oscillating fluid pressure, may eventually cause aseptic loosening of THR.     

Increased expression of EMMPRIN in the tissue around loosened hip prostheses

Matrix metalloproteinases (MMPs) have been shown to play a role in aseptic loosening of total hip replacement (THR). Extracellular matrix metallo-proteinase inducer (EMMPRIN) can upregulate expression of several MMPs but has little effect on their tissue inhibitor (TIMP)- Using the avidin-biotin-per-oxidase complex immunostaining method, we detected strong immunoreactivity of EMMPRIN in the lining-like layers, sublining area and vascular endothelium of synovial membrane-like interface tissue around loosened prostheses. In contrast, EMMPRIN staining was very weak in the synovial samples from patients with hip arthrosis. Double immunofluorescence labeling revealed EMMPRIN/MMP-1 double-positive cells in iining-iike layers and the sublining area of interface tissue.

Our findings indicate that EMMPRIN expression is upregulated in interface tissue, and that locally accumulated EMMPRIN may modulate MMP-1 expression. An imbalance in the activity of MMPs and TIMP may lead to tissue destruction and periprosthetic osteolysis. These biological responses, combined with mechanical stress caused by micromotion and oscillating fluid pressure, may eventually cause aseptic loosening of THR.     

人工关节无菌性松动界膜中的免疫反应

目的 探讨人工关节无菌性松动界膜的免疫反应状况及其与无菌性松动的关系。方法 对 9例人工关节无菌性松动界膜标本进行组织学观察 ,并行 T淋巴细胞及其亚群 (CD 3、 CD 4、 CD 8)、 IL－ 2受体 (CD 25)、巨噬细胞 (CD 68)及组织相容性抗原 (HLA－ DR)的免疫组织化学染色,观察 T淋巴细胞的表达情况及其与炎症反应的关系。结果 所有界膜标本中均可见肉芽肿性组织,有大量的巨噬细胞和异物巨细胞浸润,其中 5例 T淋巴细胞数量增加, T淋巴细胞及其亚型的分布大致相同,且 3例 T淋巴细胞呈现 IL－ 2R阳性。 T淋巴细胞的增加及 IL－ 2受体阳性的 T淋巴细胞的表达与巨噬细胞、 HLA－ DR的表达和炎症反应程度有一定的相关性。结论 在部分假体周围存在着针对假体材料的超敏反应,并且可能是导致假体无菌性松动的原因之一。     

Histological analysis and biological effects of granulation tissue around loosened hip prostheses in the development of osteolysis

Although aseptic loosening of the prosthesis is a long-term complication after total joint replacement, the detailed mechanism of osteolysis remains unknown. We examined 82 samples from 40 patients with aseptic loosened hip prostheses histologically, and compared the distribution of particles, macrophages/histiocytes, and foreign body giant cells in the retrieved tissue from capsules and around prostheses. Furthermore, to investigate the mechanism of osteolysis, we cultured tissue from a patient with massive osteolysis and examined the effects of the conditioned medium on osteoblasts in vitro. Numerous multinucleated giant cells and histiocytes were present, and polyethylene particles ranging from medium to large were identified in the polarized light. However, the distribution was heterogeneous, and no particles were found microscopically in about 30%–40% of periprosthetic tissues, and in 60% of capsules. The amount of particles correlated with giant cells, but not with histiocytes. The conditioned medium of the granulation tissue culture stimulated osteoblasts to produce interleukin-6 in both protein and mRNA, and this was in part inhibited by anti-tumor necrosis factor- or the interleukin-1 antibody, suggesting that interleukin-6 production is mediated by several cytokines. These findings suggest that interleukin-6, which is produced not only by macrophages but also by osteoblasts, is a contributing factor to aseptic loosening.     

No lymphokines in T-cells around loosened hip prostheses

Research results have been contradictory about the role of lymphocytes and immune response in aseptic loosening of total hip replacement (THR). Conclusive evidence is still lacking in spite of extensive in vivo and in vitro studies. Our study was designed to check whether T-cells were activated and if they produced lymphokines in synovial membrane-like interface tissue around loosened THRs. Tissue sections were stabilized and permeabilized to allow the cytokine-specific antibodies to penetrate through the cell membrane and the membranes of intracellular organelles. This technique, combined with computer-assisted image analysis, permits the detection and quantitation of lymphokine-producing cells. We found that the number of T-cells was low, and none of the T-cells was activated, as shown by the absence of interleukin-2 receptor (IL-2R) immunoreactivity. There was no cell producing lymphokines, such as interleukin-2 (IL-2), interferon-gamma (IFN-gamma), and tumor necrosis factor-beta (TNF-beta). Our results suggest that T-cell-mediated immune response is not actively involved in aseptic loosening of THR.     

No lymphokines in T-cells around loosened hip prostheses

Research results have been contradictory about the role of lymphocytes and immune response in aseptic loosening of total hip replacement (THR). Conclusive evidence is still lacking in spite of extensive in vivo and in vitro studies. Our study was designed to check whether T-cells were activated and if they produced lymphokines in synovial membrane-like interface tissue around loosened THRs. Tissue sections were stabilized and permeabilized to allow the cytokine-specific antibodies to penetrate through the cell membrane and the membranes of intracellular organelles. This technique, combined with computer-assisted image analysis, permits the detection and quantitation of lymphokine-producing cells. We found that the number of T-cells was low, and none of the T-cells was activated, as shown by the absence of interleukin-2 receptor (IL-2R) immunoreactivity. There was no cell producing lymphokines, such as interleukin-2 (IL-2), interferon-gamma (IFN-γ), and tumor necrosis factor-beta (TNF-β). Our results suggest that T-cell-mediated immune response is not actively involved in aseptic loosening of THR.     

无菌性松动假体周围界膜组织中PDGF-B和BMP-7受体的分布及其临床意义

目的 通过对比研究PDGF－B和BMP－7受体在无菌性松动假体周围界膜组织细胞中的分布,探讨骨－假体界膜组织的分化趋势、假体松动的生物学原因并提出防治因界膜形成而导致假体松动的相应措施。方法 以预聚合SABC法,采用PDGF－B受体（PDGFR－β）和BMP－7受体（ActR-I)的多克隆抗体分别对10例无菌性松动假体周围溶骨区和非溶骨区界膜组织行免疫组织化学染色。检测每例每种阳性各100个的相对灰度值,在不同部位的组织和细胞间进行比较。结果 界膜组织中PDGFR－β在不同细胞上的分布没有特异性,但溶骨区界膜中巨噬细胞的成纤维细胞该受体的表达量明显高于非溶骨区（P＜0．01）,并以成纤维细胞表达量较高（P＜0．05）,ActR-I主要分布于无磨损颗粒非溶骨区界中层丰富的间充质细胞或成纤维细胞上,存在磨损颗粒的界膜中细胞也可有表达。结论 溶骨和成骨因子受体在界膜组织细胞上均有分布。磨损颗粒等因素致PCGF－B表达增加可能促进界面骨溶解和纤维增生,从而造成假体的不稳定或松动。而在界面施加成骨因子则可能是在一定程度上削弱人工关节无菌性松动生物学因素的一种尝试。     

No lymphokines in T-cells around loosened hip prostheses

Research results have been contradictory about the role of lymphocytes and immune response in aseptic loosening of total hip replacement (THR). Conclusive evidence is still lacking in spite of extensive in vivo and in vitro studies. Our study was designed to check whether T-cells were activated and if they produced lymphokines in synovial membrane-like interface tissue around loosened THRs. Tissue sections were stabilized and permeabilized to allow the cytokine-specific antibodies to penetrate through the cell membrane and the membranes of intracellular organelles. This technique, combined with computer-assisted image analysis, permits the detection and quantitation of lymphokine-producing cells. We found that the number of T-cells was low, and none of the T-cells was activated, as shown by the absence of interleukin-2 receptor (IL-2R) immunoreactivity. There was no cell producing lymphokines, such as interleukin-2 (IL-2), interferon-gamma (IFN-^7;), and tumor necrosis factor-beta (TNF-^6;). Our results suggest that T-cell-mediated immune response is not actively involved in aseptic loosening of THR.     

Do non-pathogenic bacilli aggravate tissue reaction around silicone implants?

Summary Tissue reactions around various silicone implants, contaminated by Staphylococcus albus and bacillus subtilis, have been studied in rabbits by Silicone Radiation Measurements. No increase of phagocytosis was found around the contaminated materials compared to the non-contaminated implants. The morphology of the capsule was the same in the contaminated and the non-contaminated groups. Concerning the specific tissue reaction in silicone implants, a prophylactic use of antibiotics in clinical augmentation mammaplasty seems not mandatory.     

Radiation-induced capsule tissue reactions around textured breast implants in a rat model

Capsule fibrosis and other complications around various filled breast implants were evaluated in a rat radiation model after 12 months of implantation. Model implants, one per rat, were implanted subcutaneously. One month after subcutaneous implantation, high voltage radiation followed one half each group. A higher rate of capsule fibrosis occurred in radiated animals. Malignant tumors at the implantation site developed in 40% of radiated and 24% of non-radiated animals, with a much higher rate of mitosis in the radiated group (Mann-Whitney, P=0.008). The presence of an implant is a cofactor for tumor development in rats (chi2-test, chi2=6.927; P=0.008) as well as radiation, since none of the control animals developed tumors. Applied to humans, capsule contracture (fibrosis) is a common complication of radiation, while development of radiation-induced sarcoma is a rare complication after postoperative radiotherapy by all account. Still further long-term follow-up human studies are necessary.     

IL-17和IL-8在单纯BPH与合并炎症BPH患者前列腺组织中的表达

目的:探讨单纯良性前列腺增生(BPH)与伴有前列腺炎的BPH患者前列腺组织中IL-17和IL-8表达差异。方法:收集行经尿道前列腺电切术的60例BPH患者标本。根据标本HE染色不同分为单纯BPH组23例和合并炎症的BPH组37例。对两组患者的临床资料进行分析比较;用免疫组化方法检测各标本IL-17和IL-8的表达情况,用荧光定量PCR和Western印迹检测各标本IL-17和IL-8 mRNA和蛋白的表达。结果:单纯BPH组和合并炎症的BPH组患者的国际前列腺症状评分(IPSS)[(21.6±3.7)分vs(29.1±6.2)分]、生活质量评分(Qo L)[(4.4±1.6)分vs(5.4±1.3)分]、最大尿流率(Qmax)[(8.2±1.8)ml/s vs(4.7±2.1)ml/s]、残余尿量(RUV)[(98.2±19.3)ml vs(198.6±15.5)ml]、前列腺体积[(49.8±16.5)ml vs(69.2±24.1)ml]、PSA[(2.8±0.8)μg/L vs(7.4±1.9)μg/L]和C反应蛋白(CRP)[(1.5±0.6)mg/L vs(5.1±2.0)mg/L],两组相比差异明显,有统计学意义(P0.05);合并炎症的BPH组患者尿潴留的发生率[32.4%(12/37)]明显高于单纯BPH组[8.69%(2/23),P0.05];IL-17 mRNA和IL-8 mRNA在合并炎症的BPH组前列腺组织中的表达量(0.303±0.076和0.536±0.059)均明显高于单纯BPH组(0.042±0.019和0.108±0.025,P0.05);IL-17和IL-8蛋白在单纯BPH组和在合并炎症的BPH组患者前列腺组织中的蛋白表达(0.34±0.05 vs 0.88±0.10,0.43±0.04 vs1.07±0.08),两者相比差异显著,有统计学意义(P0.05)。结论:IL-17和IL-8在合并炎症的BPH患者前列腺组织中的表达上调,其可能在BPH的发生发展中起重要作用。     

无菌性松动假体－骨界面溶骨因子和成骨因子表达的对比研究

目的 对比研究无菌性松动假体周围界膜中溶骨因子和成骨因子的表达,进一步探讨磨损颗粒致界面骨溶解的生物学原因。方法 采用逆转录－聚合酶链反应（ｒｅｖｅｒｓｅ ｔｒａｎｓｃｒｉｐｔｉｏｎ ｐｏｌｙｍｅｒａｓｅ ｃｈａｉｎ ｒｅａｃｔｉｏｎ,ＲＴ－ＰＣＲ）和计算机图像分析的方法,分别检测溶骨区界膜（含磨损颗粒）和非溶骨区界膜中ＰＤＧＦ－Ｂ和ＢＭＰ－７ ｍＲＮＡ的表达量,并以正常滑膜、骨性关节炎（ｏｓｔｅ     

The use of biomedical sensors to monitor capsule formation around soft tissue implants

Piezoelectric sensors have been shown to respond reproducibly to changes in tissue mechanical properties surrounding an implant over a 4-month period. The vibrational amplitude at a frequency corresponding to the radial resonance shows a statistically significant change over time. The initial period of inflammation is marked by a significant reduction in amplitude, which is indicative of an increase in viscous dissipation of the tissue. As collagen displaces the cellular response, the amplitude continues to decrease. Finally, as the tissue matures, the capsule becomes stiffer, and the viscous dissipation lessens. These results are consistent with qualitative assessments of explanted capsules. Strain gauges encased in a monolithic block of silicone exhibited a greater degree of variability, yet show similar trends over time. The strain increases in the initial 4-week period and remains relatively steady over the following 4 weeks. Beyond 8 weeks, the gauges begin to extrude from the animal or suffer a loss of electrical continuity. Steps are being taken to improve the strain sensor longevity in the animals.     

Mechanisms of cellular recruitment in aseptic loosening of prosthetic joint implants

The association of macrophages engaged in polymethylmethacrylate (PMMA) particle phagocytosis with pockets of inflammatory cells is a pathognomonic feature of the aseptically loose interface not present at the well-fixed interface. The mechanism by which the presence of PMMA particles leads to cellular recruitment, bone resorption, and ultimate loosening is poorly understood. Granulocyte macrophage colony stimulating factor (GM-CSF) and interleukin 6 (IL-6), cytokines released by osteoblasts, stimulate the recruitment of macrophages into sites of inflammation. We show that exposure of macrophages to PMMA particles stimulated release of tumor necrosis factor (TNF), but no increase in prostaglandin E2 (PGE-2) or interleukin 1. Incubation of osteoblasts with conditioned medium from macrophages exposed to PMMA particles led to release of GMCSF, IL-6, and PGE-2. Incubation of the PMMA/macrophage medium with antibodies to TNF prior to osteoblast exposure inhibited release of GM-CSF, IL-6, and PGE-2 by the osteoblasts. Our data demonstrate that exposure of macrophages to PMMA particles leads to the release of TNF which then stimulates osteoblasts to produce GMCSF, IL-6, and PGE-2. Based upon the results of this study, we propose that the process of cellular recruitment in aseptic loosening is initiated when the mechanical failure of the cement mantle leads to the production of PMMA particles. These particles are phagocytized by macrophages leading to the production of TNF. TNF stimulates surrounding osteoblasts to produce GM-CSF, IL-6, and PGE-2 which leads to recruitment of macrophages and osteoclasts into the area of the bone-cement interface. The recruitment of these cells potentiates this process leading to bone resorption and ultimately, clinical loosening of prosthetic joint implants.     

Structure of the capsules around silicone elastomer implants

Summary Experiments were carried out on rats to determine tissue reactions to silicone rods and sheeting for up to 8 months after implantation. The connective tissue capsule forming around an implant within a few weeks is a structure well supplied with blood vessels which has an inner lining of fibrocytes and histiocytes. A typical feature of the capsules, at any time during the experimental period, was the presence of variable numbers of histiocytes in the capsule wall, in conjunction with different degrees of vascularization. Encapsulation of silicone implants does not lead to a steady state, the capsule remaining an unstable, reactive membrane.