Decellularized Apple-Derived Scaffolds for Bone Tissue Engineering In Vitro and In Vivo.

Plant-derived cellulose biomaterials have been employed in various tissue engineering applications. In vivo studies have shown the remarkable biocompatibility of scaffolds made of cellulose derived from natural sources. Additionally, these scaffolds possess structural characteristics that are relevant for multiple tissues, and they promote the invasion and proliferation of mammalian cells.

Development of hydrogel-based composite scaffolds containing eggshell particles for bone regeneration applications.

This study describes the development and characterization of novel composite scaffolds, made of an alginate-chitosan hydrogel matrix containing eggshell (ES) particles, for bone tissue engineering applications. Scaffolds with ES particles, either untreated or treated with phosphoric acid to create a nanotextured particle surface, were compared to scaffolds without particles. Results indicate that the nanotexturing process exposed occluded ES proteins orthologous to those in human bone extracellular matrix.

Effects of cobalt and chromium ions on glycolytic flux and the stabilization of hypoxia-inducible factor-1α in macrophages in vitro.

Implant wear and corrosion have been associated with adverse tissue reactions that can lead to implant failure. Wear and corrosion products are therefore of great clinical concern. For example, Co and Cr originating from CoCrMo-based implants have been shown to induce a proinflammatory response in macrophages in vitro.

Effects of cobalt and chromium ions on oxidative stress and energy metabolism in macrophages in vitro.

Cobalt and chromium ions released from cobalt-chromium-molybdenum (CoCrMo)-based implants are a potential health concern, especially since both ions have been shown to induce oxidative stress in macrophages, the predominant immune cells in periprosthetic tissues. Ions of other transition metals (Cd, Ni) have been reported to inhibit the activity of mitochondrial enzymes in the electron transport chain. However, the effects of Co and Cr ions on the energy metabolism of macrophages remain largely unknown.

Effects of metal ions on caspase-1 activation and interleukin-1β release in murine bone marrow-derived macrophages.

Ions released from metal implants have been associated with adverse tissue reactions and are therefore a major concern. Studies with macrophages have shown that cobalt, chromium, and nickel ions can activate the NLRP3 inflammasome, a multiprotein complex responsible for the activation of caspase-1 (a proteolytic enzyme converting pro-interleukin [IL]-1β to mature IL-1β). However, the mechanism(s) of inflammasome activation by metal ions remain largely unknown.

The quest for mechanically and biologically functional soft biomaterials via soft network composites.

Developing multifunctional soft biomaterials capable of addressing all the requirements of the complex tissue regeneration process is a multifaceted problem. In order to tackle the current challenges, recent research efforts are increasingly being directed towards biomimetic design concepts that can be translated into soft biomaterials via advanced manufacturing technologies. Among those, soft network composites consisting of a continuous hydrogel matrix and a reinforcing fibrous network closely resemble native soft biological materials in terms of design and composition as well as physicochemical properties.

Differential proteomic analysis of synovial fluid from hip arthroplasty patients with a pseudotumor vs. Periprosthetic osteolysis .

Adverse tissue reactions to metal implants, including pseudotumors, can compromise implant functionality and survivorship. The identification of specific proteins in the synovial fluid (SF) of hip arthroplasty patients with a pseudotumor may lead to a better understanding of the underlying pathomechanisms. The objective of the present study was to compare the protein content of SF from patients with a short-term metal-on-metal hip implant associated with a pseudotumor and patients with a long-term metal-on-polyethylene hip implant associated with periprosthetic osteolysis.

Biofabricated soft network composites for cartilage tissue engineering.

Articular cartilage from a material science point of view is a soft network composite that plays a critical role in load-bearing joints during dynamic loading. Its composite structure, consisting of a collagen fiber network and a hydrated proteoglycan matrix, gives rise to the complex mechanical properties of the tissue including viscoelasticity and stress relaxation. Melt electrospinning writing allows the design and fabrication of medical grade polycaprolactone (mPCL) fibrous networks for the reinforcement of soft hydrogel matrices for cartilage tissue engineering.

Effects of hip implant modular neck material and assembly method on fatigue life and distraction force.

Hip implant neck fractures and adverse tissue reactions associated with fretting-corrosion damage at modular interfaces are a major source of concern. Therefore, there is an urgent clinical need to develop accurate in vitro test procedures to better understand, predict and prevent in vivo implant failures. This study aimed to simulate in vivo fatigue fracture and distraction of modular necks in an in vitro setting, and to assess the effects of neck material (Ti6Al4V vs.

Effects of cobalt and chromium ions on lymphocyte migration.

A T cell-mediated hypersensitivity reaction has been reported in some patients with CoCrMo-based implants. However, the role of cobalt and chromium ions in this reaction remains unclear. The objective of the present study was to analyze the effects of Co and Cr in culture medium, as well as the effects of culture supernatants of macrophages exposed to Co or Cr , on the migration of lymphocytes.

Do patients with a failed metal-on-metal hip implant with a pseudotumor present differences in their peripheral blood lymphocyte subpopulations?

Background: Early adverse tissue reactions around metal-on-metal (MoM) hip replacements, especially pseudotumors, are a major concern. Because the causes and pathomechanisms of these pseudotumors remain largely unknown, clinical monitoring of patients with MoM bearings is challenging.

Questions/purposes: The purpose of this study was to compare the lymphocyte subpopulations in peripheral blood from patients with a failed MoM hip implant with and without a pseudotumor and patients with a well-functioning MoM hip implant without a pseudotumor.

In vitro macrophage response to nanometer-size chromium oxide particles.

An increasing number of studies have reported adverse tissue reactions around metal-on-metal (MM) hip implants. However, the origin and mechanisms of these reactions remain unclear. Moreover, the biological effects of nanometer-size chromium oxide particles, the predominant type of wear particles produced by MM implants, remain mostly unknown.

PGE₂ and BMP-2 in bone and cartilage metabolism: 2 intertwining pathways.

Osteoarthritis and lesions to cartilage tissue are diseases that frequently result in impaired joint function and patient disability. The treatment of osteoarthritis, along with local bone defects and systemic skeletal diseases, remains a significant clinical challenge for orthopaedic surgeons. Several bone morphogenetic proteins (BMPs) are known to have osteoinductive effects, whereof BMP-2 and BMP-7 are already approved for clinical applications.

New insights into wear and biological effects of metal-on-metal bearings.

Background: Despite the renewed interest in metal-on-metal implants in the past two decades, the underlying wear mechanisms and biological effects are still not fully understood.

Methods: This paper first reviews the tribology of metal-on-metal bearings, bringing new insights into the interaction of wear and corrosion, and putting the characteristics and the potential origin of wear particles in perspective with the proposed wear mechanisms. It then summarizes the current knowledge on the biological effects of particles and metal ions in relation to these wear mechanisms.

Polyethylene and metal wear particles: characteristics and biological effects.

This paper first presents a brief overview about the mechanism of wear particle formation as well as wear particle characteristics in metal-on-polyethylene and metal-on-metal artificial hip joints. The biological effects of such particles are then described, focusing on the inflammatory response induced by each type of particles as well as on how metal wear products may be the source of a T lymphocyte-mediated specific immune response, early adverse tissue responses, and genotoxicity. Finally, some of the current in vivo models used for the analysis of tissue response to various wear particles are presented.

Biologic activity of wear particles.

Aseptic loosening resulting from periprosthetic osteolysis continues to be an important cause of hip implant failure. Wear particles from the bearing surfaces play a major role in initiating periprosthetic osteolysis, which is also potentiated by mechanical factors such as increased synovial fluid pressure. The precise mechanisms by which wear particles induce periprosthetic osteolysis have not been fully elucidated and remain an active subject of research.

Controlled release of bioactive transforming growth factor beta-1 from fibrin gels in vitro.

This study analyzed the ability of fibrin gels to deliver added recombinant transforming growth factor beta-1 (TGF-beta1) in a controlled manner and biologically active form. First, the effects of the amount of TGF-beta1 on the release kinetics were analyzed using a single fibrin gel formulation (fibrinogen complex (FC) at 25 mg/mL, thrombin at 2 IU/mL). Then, the effects of FC and thrombin concentrations were analyzed.

Human mesenchymal stem cell proliferation and osteogenic differentiation in fibrin gels in vitro.

This study analyzed human mesenchymal stem cell (hMSC) behavior in a fibrin sealant. hMSC morphology, proliferation, and osteogenic differentiation were analyzed after up to 28 days of incubation in eight different formulations of fibrin gels (Tisseel) prepared with various concentrations of fibrinogen complex (FC) and thrombin. Cell morphology and distribution within the gels were observed by fluorescence microscopy after cell staining with calcein dye.

Quantitative analysis of macrophage apoptosis vs. necrosis induced by cobalt and chromium ions in vitro.

The potential toxicity of metal ions in tissues surrounding metal-metal hip replacements is a cause for concern. Previous studies conducted in our laboratory demonstrated that Co(2+) and Cr(3+) induce TNF-alpha secretion in macrophages, as well as cell mortality. However, the degree of apoptosis and necrosis remained to be investigated.

Induction of apoptosis and necrosis by metal ions in vitro.

There has been a renewed interest in the use of the metal-on-metal (MOM) implants for total hip arthroplasty (THA). It is well known, however, that the MOM articulation generates both metal particles and ions. The physiologic effects of these ions are poorly understood and their potential toxicity remains a cause for concern.

Comparison of in vitro with in vivo characteristics of wear particles from metal-metal hip implants.

The purpose of the present study was to compare wear particles isolated from metal-metal (MM) hip implants worn in an orbital bearing simulator with particles from similar MM total hip replacement (THR) implants worn in vivo. Comparison of these particles is important because it will help to assess the overall suitability of this type of hip simulator for reproducing in vivo wear and for producing physiological wear particles suitable for biological studies of in vitro cellular response. Commercial grade components made of ASTM F75 (cast) alloy were evaluated.

Effect of cobalt and chromium ions on bcl-2, bax, caspase-3, and caspase-8 expression in human U937 macrophages.

The bcl-2 and caspase families of proteins play a central role in the modulation of apoptosis. The purpose of this study was to analyze the effect of Co(2+) and Cr(3+) ions on the expression of bcl-2, bax, caspase-3 and caspase-8 to better understand the mechanisms leading to ion-induced apoptosis in macrophages. U937 human macrophages were exposed to Co(2+) and Cr(3+) ions.