Diagnosis of Metal Hypersensitivity in Total Knee Arthroplasty: A Case Report

Delayed type hypersensitivity (DTH) reactions are considered infrequent complications in arthroplasty, but have been recognized to be associated with devastating morbidity and substantial decrease in quality of life of affected patients. Chronic inflammation of artificial joints and associated loss of peri-implant bone often require revision surgery. Methods for the diagnosis of implant-related DTH are available but infrequently considered to the full extent. Sequential diagnostics based on exclusion of septic complications, local and systemic metal level determination, lymphocyte transformation testing (LTT), and local T cell subset analysis are required for an unequivocal DTH diagnosis. Here, we report on a patient with a history of chronic rheumatoid arthritis and an unfavorable outcome of unilateral knee arthroplasty. This case illustrates pitfalls and difficulties in the course of recurrent inflammation following joint replacement. In the early course, suspicion of low-grade bacterial infection led to three two-stage revisions. Afterwards, the joint was proven to be sterile. However, metal level quantification revealed release of especially cobalt and chromium from the joint, LTT indicated persisting cobalt and nickel sensitization and subset analysis of T cells from the synovium suggested DTH as a root cause for the inflammatory symptoms. This report aims to recommend the depicted diagnostic algorithm as an adequate tool for future DTH detection. Yet, systemic to local subset ratios for effector memory and regulatory T cells should be derived from sufficient patient numbers to establish it as a diagnostic marker. Moreover, future prospects regarding implant-related DTH diagnostics are discussed. Therapeutic options for the portrayed patient are proposed, considering pharmaceutical, cell-therapeutic and surgical aspects. Patients who experience peri-implant inflammation but do not have obvious mechanical or infectious problems remain a diagnostic challenge and are at high risk of being treated inadequately. Since potentially sensitizing materials are regularly used in arthroplasty, it is essential to detect cases of acute DTH-derived inflammation of an artificial joint at early postoperative stages. This would reduce the severity of inflammation-related long-term consequences for affected patients and may avoid unnecessary revision surgery

The Allergic Bone Marrow? The Immuno-Capacity of the Human Bone Marrow in Context of Metal-Associated Hypersensitivity Reactions

Arthroplasty ranks among the greatest achievements of surgical medicine, with total hip replacement termed "the operation of the century." Despite its wide success, arthroplasty bears risks, such as local reactions to implant derived wear and corrosion products. Prevalence of allergies across Western society increases and along the number of reported hypersensitivity reactions to orthopedic implant materials. In this context the main focus is on delayed hypersensitivity (DTH). This mechanism is mainly attributed to T cells and an overreaction of the adaptive immune system. Arthroplasty implant materials are in direct contact with bone marrow (BM), which is discussed as a secondary lymphoid organ. However, the mechanisms of sensitization toward implant wear remain elusive. Nickel and cobalt ions can form haptens with native peptides to activate immune cell receptors and are therefore common T helper allergens in cutaneous DTH. The rising prevalence of metal-related allergy in the general population and evidence for the immune-modulating function of BM allow for the assumption hypersensitivity reactions could occur in peri-implant BM. There is evidence that pro-inflammatory factors released during DTH reactions enhance osteoclast activity and inhibit osteoblast function, an imbalance characteristic for osteolysis. Even though some mechanisms are understood, hypersensitivity has remained a diagnosis of exclusion. This review aims to summarize current views on the pathomechanism of DTH in arthroplasty with emphasis on BM and discusses recent advances and future directions for basic research and clinical diagnostics

Multi-Parameter Analysis of Biobanked Human Bone Marrow Stromal Cells Shows Little Influence for Donor Age and Mild Comorbidities on Phenotypic and Functional Properties

Heterogeneous populations of human bone marrow-derived stromal cells (BMSC) are among the most frequently tested cellular therapeutics for treating degenerative and immune disorders, which occur predominantly in the aging population. Currently, it is unclear whether advanced donor age and commonly associated comorbidities affect the properties of ex vivo-expanded BMSCs. Thus, we stratified cells from adult and elderly donors from our biobank (n = 10 and n = 13, mean age 38 and 72 years, respectively) and compared their phenotypic and functional performance, using multiple assays typically employed as minimal criteria for defining multipotent mesenchymal stromal cells (MSCs). We found that BMSCs from both cohorts meet the standard criteria for MSC, exhibiting similar morphology, growth kinetics, gene expression profiles, and pro-angiogenic and immunosuppressive potential and the capacity to differentiate toward adipogenic, chondrogenic, and osteogenic lineages. We found no substantial differences between cells from the adult and elderly cohorts. As positive controls, we studied the impact of in vitro aging and inflammatory cytokine stimulation. Both conditions clearly affected the cellular properties, independent of donor age. We conclude that in vitro aging rather than in vivo donor aging influences BMSC characteristics

Environmental considerations and current status of grouping and regulation of engineered nanomaterials

This article reviews the current status of nanotechnology with emphasis on application and related environmental considerations as well as legislation. Application and analysis of nanomaterials in infrastructure (construction, building coatings, and water treatment) is discussed, and in particular nanomaterial release during the lifecycle of these applications. Moreover, possible grouping approaches with regard to ecotoxicological and toxicological properties, and the fate of nanomaterials in the environment are evaluated. In terms of potential exposure, the opportunities that arise from leveraging advances in several key areas, such as water treatment and construction are addressed. Additionally, this review describes challenges with regard to the European Commission’s definition of ‘nanomaterial’. The revised REACH information requirements, intended to enable a comprehensive risk assessment of nanomaterials, are outlined

Analytical and toxicological aspects of nanomaterials in different product groups: Challenges and opportunities

The widespread integration of engineered nanomaterials into consumer and industrial products creates new challenges and requires innovative approaches in terms of design, testing, reliability, and safety of nanotechnology. The aim of this review article is to give an overview of different product groups in which nanomaterials are present and outline their safety aspects for consumers. Here, release of nanomaterials and related analytical challenges and solutions as well as toxicological considerations, such as dose-metrics, are discussed. Additionally, the utilization of engineered nanomaterials as pharmaceuticals or nutraceuticals to deliver and release cargo molecules is covered. Furthermore, critical pathways for human exposure to nanomaterials, namely inhalation and ingestion, are discussed in the context of risk assessment. Analysis of NMs in food, innovative medicine or food contact materials is discussed. Specific focus is on the presence and release of nanomaterials, including whether nanomaterials can migrate from polymer nanocomposites used in food contact materials. With regard to the toxicology and toxicokinetics of nanomaterials, aspects of dose metrics of inhalation toxicity as well as ingestion toxicology and comparison between in vitro and in vivo conclusions are considered. The definition of dose descriptors to be applied in toxicological testing is emphasized. In relation to potential exposure from different products, opportunities arising from the use of advanced analytical techniques in more unique scenarios such as release of nanomaterials from medical devices such as orthopedic implants are addressed. Alongside higher product performance and complexity, further challenges regarding material characterization and safety, as well as acceptance by the general public are expected

Der Einfluss von Endoprothesenabrieb auf die periprothetische Biologie

The release of wear particles from hip endoprosthesis with metal-on-metal (MoM) bearing remains a clinical problem in hip arthroplasty. Bearing components of MoM-endoprosthesis consist of a cobalt-chromium-molybdenum (CoCrMo) alloy. Exposure to metallic wear products is related to multiple adverse effects. Most dominant local effects are pseudotumor formation and aseptic osteolysis, which leads to early implant loosening and represents the most prevalent indication for revision surgery. Furthermore, acute neurotoxic and cardiotoxic effects were described for patients who exhibit elevated systemic Co-levels. The first aim of the study was the assessment of local metal exposure. The second aim was isolating mesenchymal stromal cells (MSCs) from bone marrow (BM) of in vivo exposed patients and evaluating these cells regarding there viability, proliferation and differentiation capacity in vitro. MSCs are the precursors of rather short-lived mineralizing osteoblasts and therefore important for balanced bone homeostasis. The third aim was evaluating the functionality of MSCs from non-exposed patients following in vitro treatment with Cr(III) and/or Co(II) in relevant concentrations. The underlying hypothesis was that patients with MoM-endoprosthesis are locally exposed to Cr and Co and this exposure affects the functionality of MSCs. Graphite furnace atomic absorption spectroscopy was used to determine metal levels in periprosthetic tissue, synovial fluid and BM samples, which were collected during revision surgery of patients, who exhibited at least on osteolytic lesion. Exposure assessment demonstrated that the patients are not only exposed to particulate but also to dissociated metals. Dissociated Cr and Co were detected in all local compartments including BM. MSCs were isolated from BM of exposed patients and compared to sex and age matched non-exposed patients. In vivo exposed cells neither reveal differences in viability, proliferation, migration nor in their capacity for chondrogenic or adipogenic differentiation. However, the cells reveal an impaired capacity for osteogenic differentiation, which was quantified by diminished matrix mineralization and diminished cellular alkaline phosphatase (ALP) activity. In vitro treatment of MSCs from non-exposed patients with dissociated Cr(III) and Co(II), in non- cytotoxic but clinically relevant concentrations, confirmed these findings. Impaired osteogenesis of MSCs is most likely one important element in the pathogenesis of osteolysis. The results are potentially conferrable to other relevant exposure scenarios, like the corrosion of taper joints in modular hip implants. In preclinical testing of implant materials, not only the biocompatibility of the bulk-materials, but also the kinetics and dynamics of possible wear and corrosion products, should be evaluated to ensure maximum patient safety.Die Freisetzung von Abriebpartikeln aus Hüftendoprothesen mit einer Metall- Metall-Gleitpaarung (MoM) ist ein klinisches Problem in der Hüftendoprothetik. Die Gleitpaarungskomponenten von MoM-Endoprothesen bestehen aus einer Cobalt- Chrom-Molybdän Legierung (CoCrMo). Die Exposition gegenüber metallischen Abriebprodukten ist mit einer Vielzahl von adversen Effekten assoziiert. Dominante lokale Effekte sind Pseudotumorformationen und aseptische Osteolysen, die zu einer frühzeitigen Lockerung führen und damit die häufigste Indikation zur Revision von MoM-Endoprothesen darstellen. Des Weiteren wurden akute neurotoxische und kardiotoxische Effekte bei erhöhten systemischen Co- Spiegeln beschrieben. Das erste Ziel der Arbeit war die Bestimmung der lokalen Metallexposition. Das zweite Ziel war es mesenchymale Stromazellen (MSCs) aus dem Knochenmark (KM) von in vivo belasteten Patienten zu isolieren und in vitro hinsichtlich ihrer Viabilität, Proliferation und ihres Differenzierungspotentials zu untersuchen. MSCs sind Vorläuferzellen von kurzlebigen matrixmineralisierenden Osteoblasten und damit wichtig für die vitale Knochenhomöostase. Das dritte Ziel war es, MSCs von unbelasteten Patienten in vitro gegenüber relevanten Mengen Cr(III) und/oder Co(II) auszusetzten und ebenfalls hinsichtlich ihrer Funktionalität zu untersuchen. Die zugrundeliegende Hypothese war, dass Patienten mit MoM-Gleitpaarung lokal gegenüber Cr und Co exponiert sind und sich diese Exposition auf die Funktionalität von MSCs auswirkt. Für die Bestimmung der lokalen Metallspiegel, mittels Graphitrohr-Atomabsorptions-spektrometrie, wurde periprothetisches Gewebe, Synovialflüssigkeit und KM während der Revisionsoperation von Patienten mit mindestens einer osteolytischen Läsion entnommen. Die Expositionsbestimmung zeigte, dass Patienten mit MoM- Gleitpaarung sowohl gegenüber partikulärem, als auch gegenüber dissoziiertem Cr und Co exponiert sind. Dissoziiertes Cr und Co wurde in allen lokalen Kompartimenten, inklusive des KM, nachgewiesen. MSCs wurden aus dem KM der belasteten Patienten isoliert und mit MSCs von alters- und geschlechts- korrelierten unbelasteten Patienten verglichen. Es konnte gezeigt werden, dass in vivo exponierte Zellen nicht in ihrer Viabilität, Proliferation, Migrationskapazität und in Ihrem Potential zur chondrogenen und adipogenen Differenzierung eingeschränkt sind. Sie wiesen jedoch ein geringeres osteogenes Potential auf, welches durch eine signifikant verminderte Matrixmineralisierung und erniedrigter zellulärer Aktivität der alkalischen Phosphatase (ALP) nachgewiesen wurde. Die in vitro Behandlung von MSCs unbelasteter Patienten mit dissoziiertem Cr(III) und Co(II), in nicht zytotoxischen jedoch klinisch relevanten Konzentrationen, bestätigte diese Ergebnisse. Die beeinträchtigte Osteogenese von MSCs ist sehr wahrscheinlich ein weiterer wichtiger Bestandteil der Pathogenese von Osteolysen. Die erzielten Ergebnisse lassen sich möglicherweise auch auf andere Expositionszenarien, wie die Korrosion von Konussteckverbindungen bei modularen Hüftendoprothesen, übertragen. Um maximale Patientensicherheit zu gewährleisten, sollte bei der präklinischen Testung von Implantatmaterialien nicht nur die Biokompatibilität der Bulk-Materialien, sondern auch die Kinetik und Dynamik von möglichen Abrieb- und Korrosionsprodukten evaluiert werden

The Applications of Microphysiological Systems in Biomedicine: Impact on Urologic and Orthopaedic Research

Definition Microphysiological systems (MPSs) are in vitro models that can incorporate dynamic stimuli such as flow, pressure and contraction in cell culture, enabling the formation of cellular architectures and retrieving physiological function often absent in conventional 2D-cell culture. MPS applications saw a substantial growth in recent years, drawing attention from industry as a strategy to optimize pre-clinical drug-development purposes, as well as from biomedical research, to fill a gap between in vivo and in vitro models. Several MPS platforms are now available and are employed in the development of bone and kidney complex systems for urologic and orthopaedic research. These advances have enabled, for example, the in vitro modelling of bone regeneration and renal drug secretion, and have dramatic potential to improve research into both orthopaedic and urology cancers

Scaffold Guided Bone Regeneration for the Treatment of Large Segmental Defects in Long Bones

Bone generally displays a high intrinsic capacity to regenerate. Nonetheless, large osseous defects sometimes fail to heal. The treatment of such large segmental defects still represents a considerable clinical challenge. The regeneration of large bone defects often proves difficult, since it relies on the formation of large amounts of bone within an environment impedimental to osteogenesis, characterized by soft tissue damage and hampered vascularization. Consequently, research efforts have concentrated on tissue engineering and regenerative medical strategies to resolve this multifaceted challenge. In this review, we summarize, critically evaluate, and discuss present approaches in light of their clinical relevance; we also present future advanced techniques for bone tissue engineering, outlining the steps to realize for their translation from bench to bedside. The discussion includes the physiology of bone healing, requirements and properties of natural and synthetic biomaterials for bone reconstruction, their use in conjunction with cellular components and suitable growth factors, and strategies to improve vascularization and the translation of these regenerative concepts to in vivo applications. We conclude that the ideal all-purpose material for scaffold-guided bone regeneration is currently not available. It seems that a variety of different solutions will be employed, according to the clinical treatment necessary

Scaffold Guided Bone Regeneration for the Treatment of Large Segmental Defects in Long Bones

Bone generally displays a high intrinsic capacity to regenerate. Nonetheless, large osseous defects sometimes fail to heal. The treatment of such large segmental defects still represents a considerable clinical challenge. The regeneration of large bone defects often proves difficult, since it relies on the formation of large amounts of bone within an environment impedimental to osteogenesis, characterized by soft tissue damage and hampered vascularization. Consequently, research efforts have concentrated on tissue engineering and regenerative medical strategies to resolve this multifaceted challenge. In this review, we summarize, critically evaluate, and discuss present approaches in light of their clinical relevance; we also present future advanced techniques for bone tissue engineering, outlining the steps to realize for their translation from bench to bedside. The discussion includes the physiology of bone healing, requirements and properties of natural and synthetic biomaterials for bone reconstruction, their use in conjunction with cellular components and suitable growth factors, and strategies to improve vascularization and the translation of these regenerative concepts to in vivo applications. We conclude that the ideal all-purpose material for scaffold-guided bone regeneration is currently not available. It seems that a variety of different solutions will be employed, according to the clinical treatment necessary

Biocompatible Gas Plasma Treatment Affects Secretion Profiles but Not Osteogenic Differentiation in Patient-Derived Mesenchymal Stromal Cells

Cold physical plasma (CPP), a partially ionized gas that simultaneously generates reactive oxygen and nitrogen species, is suggested to provide advantages in regenerative medicine. Intraoperative CPP therapy targeting pathologies related to diminished bone quality could be promising in orthopedic surgery. Assessment of a clinically approved plasma jet regarding cellular effects on primary bone marrow mesenchymal stromal cells (hBM-MSCs) from relevant arthroplasty patient cohorts is needed to establish CPP-based therapeutic approaches for bone regeneration. Thus, the aim of this study was to derive biocompatible doses of CPP and subsequent evaluation of human primary hBM-MSCs’ osteogenic and immunomodulatory potential. Metabolic activity and cell proliferation were affected in a treatment-time-dependent manner. Morphometric high content imaging analyses revealed a decline in mitochondria and nuclei content and increased cytoskeletal compactness following CPP exposure. Employing a nontoxic exposure regime, investigation on osteogenic differentiation did not enhance osteogenic capacity of hBM-MSCs. Multiplex analysis of major hBM-MSC cytokines, chemokines and growth factors revealed an anti-inflammatory, promatrix-assembling and osteoclast-regulating secretion profile following CPP treatment and osteogenic stimulus. This study can be noted as the first in vitro study addressing the influence of CPP on hBM-MSCs from individual donors of an arthroplasty clientele