Exosomes From Human Urine-Derived Stem Cells Encapsulated Into PLGA Nanoparticles for Therapy in Mice With Particulate Polyethylene-Induced Osteolysis

Background: Periprosthetic osteolysis is the primary reason for arthroplasty failure after total joint replacement because of the generation of wear particles and subsequent bone erosion around the prosthesis, which leads to aseptic loosening. Periprosthetic osteolysis is often treated with revision surgery because of the lack of effective therapeutic agents. As key messengers of intercellular interactions, exosomes can be independently used as therapeutic agents to promote tissue repair and regeneration. In this study, we fabricated poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) that carry exosomes derived from human urine stem cells (USC-Exos) and explored their effects on polyethylene-induced osteolysis.Methods: USCs were identified by multipotent differentiation and flow cytometry analyses. USC-Exos were isolated and identified by transmission electron microscopy (TEM), dynamic light scattering (DLS), and western blotting. PLGA microspheres containing USC-Exos were fabricated to synthesize NPs using the mechanical double-emulsion method. The obtained NPs were characterized in terms of stability, toxicity, exosome release, and cell uptake. Then, these NPs were implanted into the murine air pouch model, and their effects on polyethylene-induced osteolysis were evaluated by microcomputed tomography (micro-CT) and histological analyses.Results: The average NP diameter was ~282 ± 0.4 nm, and the zeta potential was −2.02 ± 0.03 mV. After long-term storage at room temperature and 4°C, the NP solution was stable without significant coaggregation. In vitro release profiles indicated sustained release of exosomes for 12 days. In vivo, injection of NPs into the murine air pouch caused less osteolysis than that of USC-Exos, and NPs significantly reduced bone absorption, as indicated by histology and micro-CT scanning.Conclusion: Our findings suggest that USC-Exo-based PLGA NPs can prevent particulate polyethylene-induced osteolysis and bone loss.

The wettability of electron spun membranes by synovial fluid

Aseptic loosening due to periprosthetic osteolysis has been accepted as one of the leading causes of revision procedures in patients with previous joint arthroplasty. Recently, several strategies for suppression of osteolysis were proposed, mostly based on biological treatment such as mitigation of chronic inflammatory reactions. However, these biological treatments do not stop the debris migration but only reduce the inflammatory reaction. To address this shortcoming, we propose the concept of ultrahigh molecular weighted polyethylene particles filtration storage by electrospun membranes. Firstly, the surface tension of synovial fluid (SF) is obtained by use of a pendant droplet. Secondly, the contact angle of the electrospun membranes wetted by two different liquids is measured to obtain the free surface energy using of the Owens–Wendt model. Additionally, the wettability of electrospun membranes by SF as a function of technology parameters is studied.

Formation of bone extracellular matrix in a rotational bioreactor: Preseeding of human mesenchymal stromal cells on a thin polymer scaffold

BACKGROUND: Periprosthetic osteolysis is known to be the main reason for aseptic instability after the arthroplasty or dental implantation. The use of tissue-engineered scaffolds that allow bone formation area, produced using flow or rotational bioreactor, seems to be a promising approach for such bone lesions treatment. OBJECTIVE: To evaluate the bone neo-extracellular matrix formation within the three-week culture of a scaffold in a coaxial rotational bioreactor generating the preliminary mathematically modelled FSS values with the aim to develop a tissue-engineered scaffold for periprosthetic osteolysis prevention, but reactor critical characteristics like fluid shear stress (FSS) should be fine-tuned to achieve good cell density and prevent cell loss by the scaffold. METHODS: Thin film biodegradable polymer carrier, produced with electrospun and then seeded with hMSCs (human mesenchymal stromal cell) and culture for three weeks in rotational bioreactor, which generates the preliminary math model-calculated FSS from 4 to 8 mPa. Results were assessed with laser scanning confocal microscopy with immunofluorescence, and electron scanning microscopy with spectroscopy. RESULTS: After two weeks of culture, there were no significant differences between the density of hMSC cultured in the static conditions and bioreactor but after 3 weeks the cell density in the bioreactor increased by 35% compared to the static conditions (up to 3.53×106±462 per 1 cm2, P < 0.001). The immunofluorescence intensity exhibited by type I collagen after two and three weeks of culture increased 2.5-fold (48.3±0.39 a.u., P < 0.001) and 1.31-fold (74.0±0.29 a.u., P < 0.001) in the bioreactor, but for osteopontin after 3 weeks of culture in the static conditions was similar to those in the bioreactor. CONCLUSIONS: Optimization of the reactor characteristics with the mathematically modelled FSS values could significantly improve cell proliferation, differentiation, and enhanced formation of the neo-extracellular matrix within 3 weeks in the rotational bioreactor.

Cimifugin Suppresses NF-κB Signaling to Prevent Osteoclastogenesis and Periprosthetic Osteolysis

Background: Aseptic loosening of prosthesis (ALP) is one of the most common long-term complications of knee and hip arthroplasty. Wear particle-induced osteoclastogenesis and subsequent periprosthetic osteolysis account for the morbidity of ALP. Here, we investigate the potential of cimifugin (CIM), a natural extract from Cimicifuga racemosa and Saposhnikovia divaricata, as a bone-protective drug in the treatment of ALP.Method: First, we performed cell viability and osteoclast formation assays to assess the effect of noncytotoxic CIM on osteoclast differentiation in vitro. Bone slice resorption and F-actin ring immunofluorescence assays were adopted to assess the effects of CIM on bone-resorption function. Then, quantitative real-time polymerase chain reaction (qRT–PCR) analysis was performed to further assess the repressive effects of CIM on osteoclastogenesis at the gene expression level. To elucidate the mechanisms underlying the above findings, Western blot and luciferase reporter gene assays were used to assess the regulatory effects of CIM on the NF-κB and MAPK signaling pathways. Moreover, a Ti particle-induced murine calvarial osteolysis model and subsequent histomorphometric analysis via micro-CT and immunohistochemical staining were used to elucidate the effect of CIM on periprosthetic osteolysis in vivo.Result: CIM dose-dependently inhibited both bone marrow-derived macrophage (BMM)- and RAW264.7 cell-derived osteoclastogenesis and bone resorption pit formation in vitro, which was further supported by the reduced expression of F-actin and osteoclast-specific genes. According to the Western blot analysis, inhibition of IκBα phosphorylation in the NF-κB signaling pathway, not the phosphorylation of MAPKs, was responsible for the suppressive effect of CIM on osteoclastogenesis. Animal experiments demonstrated that CIM alleviated Ti particle-induced bone erosion and osteoclast accumulation in murine calvaria.Conclusion: The current study suggested for the first time that CIM can inhibit RANKL-induced osetoclastogenesis by suppressing the NF-κB signaling pathway in vitro and prevent periprosthetic osteolysis in vivo. These findings suggest the potential of CIM as a therapeutic in ALP.

Long-Term Outcomes of Radial Head Arthroplasty in Complex Elbow Fracture Dislocation

The purpose of the current study was to investigate the long-term outcomes of radial head arthroplasty in complex elbow injuries through radiographic analysis and functional correlation. We evaluated 24 radial head arthroplasties in 24 consecutive patients with complex elbow fracture dislocation. All patients were treated with a single type of modular monopolar prosthesis containing smooth stem in press-fit implantation. Clinical survey using the Mayo Elbow Performance Score (MEPS), self-reported scales of shortened Disabilities of the Arm, Shoulder, and Hand (QuickDASH) and the visual analog scale (VAS) at more than 10-year follow-up were reported and compared to 2-year outcomes. Periprosthetic osteolysis was measured in the 10 zones of prosthesis-cortical interface with a modified radiolucency score, which was calibrated by each prosthesis size. Pearson correlation analysis was performed to detect the association between periprosthetic radiolucency and clinical assessment. At the final follow-up, MEPS, QuickDASH score and VAS score averaged 82.5 ± 15, 14.1 ± 14.3 and 1.6 ± 1.2 respectively. A decline in functional status was noted, with decreased mean MEPS and increased mean QuickDASH and VAS scores as compared to the 2-year results while the difference was insignificant. Periprosthetic osteolysis was more prevalent around stem tip of zone 3 and zone 8. The final and 2-year radiolucency scores averaged 7.4 ± 4.2 and 2.6 ± 2.3 respectively with significant difference. Pearson correlation analysis indicated that the difference between radiolucency scores and clinical outcomes in MEPS/QuickDASH/VAS was −0.836, 0.517 and 0.464. Progression of periprosthetic osteolysis after postoperative 10 years is more prevalent around the stem tip with moderate to high correlation to clinical outcomes. Sustained follow-up is warranted to justify subsequent surgery for revision or implant removal.

Volume and Distribution of Periprosthetic Bone Cysts in the Distal Tibia and Talus before Early Revision of Total Ankle Arthroplasty

Periprosthetic osteolysis is a common complication following total ankle arthroplasty (TAA). However, understanding of osteolysis volume and distribution is still evolving, undermining efforts to reduce the incidence of osteolysis via bone remodeling. We obtained data on the characteristics of osteolysis developing within the distal tibia and talus after TAA. Three-dimensional computed tomography (3D-CT) reconstructions of 12 patients who underwent HINTEGRA TAA were performed. We identified 27 volumes of interest (VOIs) in the tibia and talus and used statistical methods to identify the characteristics of osteolysis in the VOIs. The osteolysis volume was significantly larger in the talus than in the tibia (162.1 ± 13.6 and 54.9 ± 6.1 mm3, respectively, p = 0.00). The extent of osteolysis within the peri-prosthetic region was greater than within other regions (p < 0.05). Particularly, in the talus, the region around the talar pegs exhibited 24.2 ± 4.5% more osteolysis than any other talar region (p = 0.00). Our results may suggest that extensive osteolysis within the peri-prosthetic region reflects changes in stress flow and distribution, which vary according to the design and placement of the fixation components. This is the first study to report 3D osteolysis patterns after TAA. Careful planning of TAA design improvements may reduce the incidence of osteolysis. Our results will facilitate the further development of TAA systems.

Effect of Oxidative Stress on Bone Remodeling in Periprosthetic Osteolysis

The success of implant performance and arthroplasty is based on several factors, including oxidative stress-induced osteolysis. Oxidative stress is a key factor of the inflammatory response. Implant biomaterials can release wear particles which may elicit adverse reactions in patients, such as local inflammatory response leading to tissue damage, which eventually results in loosening of the implant. Wear debris undergo phagocytosis by macrophages, inducing a low-grade chronic inflammation and reactive oxygen species (ROS) production. In addition, ROS can also be directly produced by prosthetic biomaterial oxidation. Overall, ROS amplify the inflammatory response and stimulate both RANKL-induced osteoclastogenesis and osteoblast apoptosis, resulting in bone resorption, leading to periprosthetic osteolysis. Therefore, a growing understanding of the mechanism of oxidative stress-induced periprosthetic osteolysis and anti-oxidant strategies of implant design as well as the addition of anti-oxidant agents will help to improve implants’ performances and therapeutic approaches.

Osteoblasts-derived Exosomes as Novel Communicators in Particle Induced Periprosthetic Osteolysis

BackgroundThe inflammatory response to titanium implant-derived wear particles is considered as the hallmark of periprosthetic osteolysis, an event that cause pain, reduce patient motility, ultimately leading to the need of a revision surgery. Although macrophages are major cell players, other cell types such as bone cells can indirectly contribute to periprosthetic osteolysis, however the mechanisms are not fully understood. Exosomes (Exos) has been related with several bone pathologies, with growing body of literature recognizing them as actively shuttle molecules through the body, with their cargo being completely dependent of external stimuli (e.g. chemicals and metals ions and particles). Till the moment, the role of wear debris on osteoblasts exosomes biogenesis is absent and the possible contribution of Exos to osteoimmune communication and periprosthetic osteolysis is still in its infancy. Taking that in consideration, in this work we investigate the effect of wear debris on Exo biogenesis, where two bone cell models were exposed to titanium dioxide nanoparticles (TiO2 NPs) similar in size and composition to wear debris associated with prosthetic implants. The contribution of Exos to periprosthetic osteolysis was evaluated performing functional tests stimulating primary human macrophages with bone-derived Exos.ResultsFor the first time, we report that TiO2 NPs enter in multivesicular bodies, the nascent of Exos and altered osteoblasts derived exosomes secretion and cargo. No significant differences were observed in Exos morphology and size, however mass spectrometry analysis identified urokinase-type plasminogen activator (uPA), specifically enriched in Exos derived from bone cells pre-incubated with TiO2 NPs. Functional tests confirmed the activation of human macrophages towards a mixed phenotype with consequent secretion of pro and anti-inflammatory cytokines. ConclusionsThe external stimuli of osteoblasts to TiO2 NPs induced a dose dependent secretion of Exos, suggesting alterations in their biogenesis as well as in their cargo. Functional tests reveal that enriched uPA exosomal cargo is stimulating macrophages towards a mixed M1 and M2 phenotype inducing the release of pro-and anti-inflammatory signals that are characteristic of periprosthetic osteolysis. Interestingly, uPA may be proposed, in the future, as a possible candidate biomarker to early diagnose particle induced periprosthetic osteolysis, since uPA was also detected in the pseudocapsular interface around implants of patients with loosening of total hip prosthesis and joint replacement surgery, suggesting their active role in disease progression.