Flow cytometric technique for the detection of phagocytosed wear particles in patients with total joint arthroplasty

Micro and Nanoplastic Contamination and Its Effects on Freshwater Mussels Caged in an Urban Area

Plastic-based contamination has become a major cause of concern as it pervades many environments such as air, water, sediments, and soils. This study sought to examine the presence of microplastics (MPs) and nanoplastics (NPs) in freshwater mussels placed at rainfall/street runoff overflows, downstream (15 km) of the city centre of Montréal, and 8 km downstream of a municipal effluent dispersion plume. MPs and NPs were determined using flow cytometry and size exclusion chromatography using fluorescence detection. Following 3 months of exposure during the summer season, mussels contained elevated amounts of both MPs and NPs. The rainfall overflow and downstream of the city centre were the most contaminated sites. Lipid peroxidation, metallothioneins, and protein aggregates (amyloids) were significantly increased at the most contaminated sites and were significantly correlated with NPs in tissues. Based on the levels of MPs and NPs in mussels exposed to municipal effluent, wastewater treatment plants appear to mitigate plastic contamination albeit not completely. In conclusion, the data support the hypothesis that mussels placed in urbanized areas are more contaminated by plastics, which are associated with oxidative damage. The highest responses observed at the overflow site suggest that tire wear and/or asphalt (road) erosion MPs/NPs represent important sources of contamination for the aquatic biota.

Popliteal Skin Lesion due to Wear Disease in Total Knee Arthroplasty: A Case Report

CASE

An 87-year-old woman presented with a popliteal skin lesion due to polyethylene wear 13 years following a left total knee arthroplasty. Excisional biopsy through a posterior approach was performed. Histology showed inflammation with granulomas and birefringent foreign body particles in the skin. Cultures remained negative, and revision knee arthroplasty was performed.

CONCLUSIONS

A popliteal skin lesion due to polyethylene wear disease in total knee arthroplasty has not previously been described. Patients with an atypical inflammation of the skin with an underlying joint implant should be referred to an orthopaedic surgeon, and dermal biopsies should be checked for birefringent material.

LEVEL OF EVIDENCE

Level V.

The induction of CXCR4 expression in human osteoblast-like cells (MG63) by CoCr particles is regulated by the PLC-DAG-PKC pathway

BACKGROUND

Osteolysis which leads to aseptic loosening of implants is a fundamental problem in joint replacement surgery (arthroplasty) and the leading cause for implant failure and revision surgery. Metal (CoCr) particles separated from implants by wear cause osteolysis and the failure of orthopedic implants, but the molecular mechanism is not clear. The chemokine receptor CXCR4 has been shown to play a pivotal role in periprosthetic osteolysis. The aim of this study was to determine which signal transduction pathway (PLC-DAG-PKC or MAPK/ERK) induces CXCR4 expression in osteoblast-like cells (MG63) cells.

METHODS

MG63 and Jurkat cells were stimulated with different amounts of particles (10⁷ , 10⁶ , and 10⁵ ) for different time periods (30 min to 24 h), in the presence and absence of specific inhibitors (chelerythrine for the PLC-DAG-PKC pathway and PD98059 for the MAPK/ERK pathway). The expression of CXCR4-specific mRNA was determined by real-time polymerase chain reaction (PCR), and the PKC activity was measured by Western Blot using an antibody specific for PKC-related phosphorylation.

RESULTS

Real-time PCR data showed that CXCR4 mRNA expression in MG63 cells induced by CoCr particles was significantly diminished by the PKC-specific inhibitor chelerythrine. This effect was not observed with the MAPK/ERK inhibitor PD98059. The involvement of PKC was also confirmed by an intensified phosphorylation pattern after stimulation with CoCr particles. In Jurkat cells, none of the inhibitors exhibited any effect.

CONCLUSION

The induction of CXCR4-specific mRNA expression in MG63 cells after stimulation with CoCr particles is regulated by the PLC-DAG-PKC pathway and not by the MAPK/ERK pathway. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2326-2332, 2017.

Simultaneous flow cytometric measurement of antigen attachment to phagocytes and phagocytosis

The current available assays cannot differentiate the stages of phagocytosis. We, therefore, established methods for concurrent detection of antigen attachment and engulfment by phagocyte using latex beads coated with lipopolysaccharide, rabbit IgG, and carboxyfluorescein diacetate succinimidyl ester. The generated beads were incubated with whole blood at 37°C for 1 hr and stained with PE-Cy5.5 anti-rabbit IgG antibody. By flow cytometry, attachment and phagocytic processes could be detected, simultaneously. The established method is a valuable tool for diagnosis of phagocytic disorder and study of molecules involved in phagocytosis.

Polyethylene wear particles play a role in development of osteoarthritis via detrimental effects on cartilage, meniscus, and synovium

OBJECTIVE

While ultra-high molecular weight polyethylene (UHMWPE) wear particles are known to cause periprosthetic osteolysis, its interaction with other intra-articular tissues in the case of partial joint arthroplasties is not well understood. We hypothesized that UHMWPE particles per se would interact with intra-articular tissue, which by acting as inflammatory reservoirs, would subsequently induce osteoarthritic (OA) changes. Our goal was to assess the inflammatory response, phagocytic activity, as well as apoptosis of intra-articular cells in the presence of UHMWPE particles in vitro, and the in vivo response of those tissues after intra-articular injection of particles in a murine model.

DESIGN

Three cell types were used for the in vitro study; chondrocytes, meniscal fibrochondrocytes, and synoviocytes. Each cell type was cultured with two different concentrations of UHMWPE particles. Pro-inflammatory cytokine production, phagocytosis, and apoptosis were analyzed. In vivo experiments were done by injecting two concentrations of UHMWPE particles into normal and murine OA model knee joints.

RESULTS

In vitro experiments showed that UHMWPE particles increase pro-inflammatory cytokine and mediator (IL-1β, IL-6, TNF-α, Nitric Oxide, and Prostaglandin E2) production, phagocytosis of particles, and apoptosis in all cell types. In vivo experiment showed degeneration of cartilage and meniscus, as well as synovitis after particle injection.

CONCLUSIONS

UHMWPE wear particles per se exert detrimental effects in cartilage, synovium, and meniscus of the knee joint resulting in pro-inflammatory cytokine release, phagocytosis of particles and apoptosis. Particles induced and exacerbated OA changes in a murine model.

Nano-osteoimmunology as an important consideration in the design of future implants

The size of wear particles emanating from a prosthesis at interfaces is critical to the interfacial properties of the joint replacement and responses from the biological environment. Nanoscale particles in particular require investigation. This project aimed to evaluate the osteoimmunological response to nanoscale ultrahigh molecular weight polyethylene (UHMWPE) wear particles in vitro, including dendritic cells (DCs), macrophages, osteoclasts (OCs), cytokine secretion, and co-cultured OCs and osteoblasts (OBs). The wear particles generated from a constant-load knee prosthesis actuator were profiled using atomic force microscopy and fractionated into sizes of 0.05-0.2, 0.2-0.8, 0.8-1, 1-5 and 5-10 μm. The fractions were exposed to DCs isolated from mice spleen, human OCs, and co-cultured human OBs and OCs, and the effects of the particles on the cells were determined. Results revealed that exposure to nanoscale UHMWPE wear particles induced significant DC activation (p<0.05) and consequently increased cytokine interleukin (IL)-6 and IL-1β secretion (p<0.05). Exposure to nanoscale particles promoted OC maturation, resulting in the suppression of OB proliferation in OB and OC co-cultures. Therefore, the results of this study could contribute to a more mechanistic understanding of wear-debris-associated prosthesis failure. Furthermore, nanoscale UHMWPE wear particles should be considered as mediators of periprosthetic inflammation in the future development of biomaterials for joint replacement bearing surfaces.

Five types of inflammatory arthritis following total knee arthroplasty

Joint effusion after total knee arthroplasty (TKA) is considered as a manifestation of certain inflammatory reactions within prosthetic joints. This study investigated causes of joint effusion following TKA and analyzed phenotypic characteristics of synovial fluid leukocytes for each cause. Forty-six TKAs for rheumatoid arthritis (RA) and 49 TKAs for osteoarthritis (OA) displaying joint effusion were investigated. Causes of joint effusion were clinically identified and frequencies of each cause were compared between RA and OA. Synovial fluid cell phenotypes were analyzed using a fluorescence-activated cell sorter. Clinical diagnoses for joint effusion were classified into five different groups: deep infection (DI); increased activity of RA (IRA); particle-induced synovitis (PS); metal sensitivity (MS); and nonspecific synovitis (NS). The most frequent cause of post-TKA effusion was IRA in RA, and NS in OA. Biomaterial-related arthritis such as PS and MS were more frequent with OA than with RA. Analysis of synovial fluid cell phenotypes revealed that the characteristic cells for each diagnosis were CD16(+)CD14(-) neutrophils in IRA and DI, CD14(+) macrophages in PS, and CD3(+)CD45RO(+) T cells in MS. Post-TKA joint effusion is clinically caused by five different types of arthritis. Phenotypic characteristics of synovial fluid leukocytes reflect joint pathology and contribute to diagnosis and exclusion of biomaterial-related arthritis.

How much sterile saline should be used for efficient lavage during total knee arthroplasty? Effects of pulse lavage irrigation on removal of bone and cement debris

Bone and polymethyl methacrylate (PMMA) debris particles generated during total knee arthroplasty (TKA) reportedly cause third-body wear. The present study investigated the volume of pulse lavage sufficient for removal of intraoperative PMMA and bone particles. Subjects comprised 8 patients who underwent cemented TKA. Pulse lavage with 8 L of sterile saline was performed using a pulsatile irrigator. During pulse lavage, aspirated fluid was collected in a 1-L aliquot, and the number and size of bone and PMMA particles in each fluid were measured. Image analysis revealed that the number of particles peaked at first lavage and gradually decreased until eighth lavage. Significant differences were found between the first vs second, second vs third, and third vs fourth lavage. However, no significant differences were found beyond the fourth lavage. This study indicated that 4 L of pulse lavage is effective for removing the particles during cemented TKA.

The nonopsonic allogeneic cell phagocytosis of macrophages detected by flow cytometry and two photon fluorescence microscope

Phagocytosis, one of the apparent functions for macrophages, represents an early and crucial event in triggering host defenses against invading pathogens as well as allo- or xenogeneic rejection. Now, some methods have been used in detecting the opsonic phagocytosis of macrophages in xenogeneic settings. Efficient nonopsonic phagocytosis analysis method has not been established yet. In the present studies, allogeneic lymphocytes pre-labeled with 5-(and-6)-carboxyfluorescein diacetate succinimidyl ester (CFSE) or derived from green fluorescent protein transgeneic B6 mice (GFP-B6 mice) were co-incubated with primary murine peritoneal macrophages (PEMs) for 1-2 h or were injected into murine peritoneal cavity for 30 to 240 min. Assays by flow cytometry (FCM) and two photon laser scanning microscope (TPM) showed an efficient uptake of both allogeneic lymphocytes and xenogeneic chicken red blood cells. The continuing process of nonopsonic phagocytosis of allogeneic lymphocytes by PEMs was recorded by TPM. Furthermore, the phenotype differences of PEMs with or without phagocytosis of allogeneic cells were determined by three-color FCMs. Significantly upregulated expressions of CD11b, CD44, TLR2 and TLR4 on PEMs were observed as early as 6 h after phagocytosis of allogeneic cells. Our present data indicated that the FCM and TPM combined method is a practical approach to detect macrophage nonopsonic phagocytosis of allogeneic lymphocytes and to identify the phenotype alteration of macrophages after phagocytosis.

Compliant layer acetabular cups: friction testing of a range of materials and designs for a new generation of prosthesis that mimics the natural joint

Total joint replacements (TJRs) have a limited lifetime, but the introduction of components that exhibit good lubricating properties with low friction and low wear could extend the life of TJRs. A novel acetabular cup design using polyurethane (PU) as a compliant layer (to mimic the natural joint) has been developed. This study describes a series of friction tests that have been used to select the most appropriate material, optimize the design parameters, and fine-tune the manufacturing processes of these joints. To determine accurately the mode of lubrication under which these joints operate, a synthetic lubricant was used in all these tests. Friction tests were carried out to assess the lubrication of four PU bearing materials. Corethane 80A was the preferred material and was subjected to subsequent testing. Friction tests conducted on acetabular cups, manufactured using Corethane 80A articulating against standard, commercially available femoral heads, demonstrated friction factors approaching those for full-fluid-film lubrication with only approximately 1 per cent asperity contact. As the joint produces these low friction factors within less than half a walking cycle after prolonged periods of loading, start-up friction was not considered to be a critical factor. Cups performed well across the full range of femoral head sizes, but a number of samples manufactured with reduced radial clearances performed with higher than expected friction. This was caused by the femoral head being gripped around the equator by the low clearance cup. To avoid this, the cup design was modified by increasing the flare at the rim. In addition to this the radial clearance was increased. As the material is incompressible, a radial clearance of 0.08 mm was too small for a cup diameter of 32 mm. A clearance of between 0.10 and 0.25 mm produced a performance approaching full-fluid-film lubrication. This series of tests acted as a step towards the optimization of the design of these joints, which has now led to an in vivo ovine model.