Search

Objective: Irrigation is a conventional treatment for acute and chronic periprosthetic joint infections (PJI). However, there has been no unified standard for irrigation during surgery for PJI in the past, and the efficacy is uncertain. The purpose of this study is to create a new irrigation protocol to enhance the infection control rate and reduce the postoperative recurrence rate of PJI patients. Methods: We conducted a single‐institution retrospective review with a total of 56 patients who underwent revision total hip or knee arthroplasties due to PJI from January 2011 to January 2022. Conventional irrigation (CI) was used in 32 cases, and standard operating procedure of irrigation (SOPI) was used in 24. The CI protocol carries out an empirical irrigation after debridement, which is quite random. Our SOPI protocol clearly stipulates the soaking concentration and time of hydrogen peroxide and povidone‐iodine. The irrigation is carried out three times, and tissue samples are taken from multiple parts before and after irrigation, which are sent for microbial culture. The important statistical indicators were the rate of positive microbiological culture and postoperative recurrence rate with an average follow‐up of 24 average months. Results: The drainage volume was lower in the SOPI group than in the CI group on postoperative day 3 (p < 0.01) and 7 (p = 0.016). In addition, the percentage of positive microbiological cultures after the third irrigation was less than that before (p < 0.01) and after (p < 0.01) the first irrigation. The most common causative organism was Staphylococcus aureus, which was detected in 25.0% and 12.5% of the SOPI and CI groups, respectively. The failure rate at the final follow‐up was 8.3% and 31.3% (p = 0.039) for the SOPI and CI groups, respectively. Conclusion: Compared with the traditional CI method, SOPI standardized the soaking time of hydrogen peroxide and povidone‐iodine, increased the frequency of and irrigation, and proved that microorganisms were almost completely removed through the microbial culture of multiple tissues. SOPI has the potential to become a standardized irrigation process worthy of promotion, effectively reducing the postoperative recurrence rate of PJI patients. [ABSTRACT FROM AUTHOR]

Bone marrow mesenchymal stem cells (BMMSCs) transplantation methods are promising candidates for osteoarthritis (OA) treatment. However, inflammatory factors (such as TNF‐α) that occur at cell transplantation sites are critical factors that impair the effectiveness of the treatment. Previous studies have shown that aspirin (AS) had a regulatory role in stem cell differentiation. However, little is known about the role of AS on the chondrogenesis of BMMSCs. The purpose of this study is to explore the protective role of AS against the negative effects of TNF‐α on BMMSC chondrogenesis. In this study, we investigated the effects of AS and TNF‐α on BMMSCs chondrogenesis by performing the Alcian Blue staining, safranin O‐fast green staining, haematoxylin and eosin staining, and immunohistochemical staining, as well as real‐time RT‐PCR and western blot assays. Our results demonstrated that TNF‐α inhibited chondrogenic differentiation of BMMSCs by disrupting the balance of cartilage metabolism and promoting oxidative stress in BMMSCs, while AS treatment attenuated these effects. Furthermore, a detailed molecular mechanistic analysis indicated that Yes‐associated protein (YAP) played a critical regulatory role in this process. In addition, AS treatment mitigated the progression of cartilage degeneration in a mouse destabilization of the medial meniscus (DMM) model. AS alleviated the inhibitory effect of TNF‐α on chondrogenesis of BMMSCs by stabilizing YAP, which may provide new therapeutic strategies for OA treatment. [ABSTRACT FROM AUTHOR]

Objectives: Osteoarthritis (OA) is a degenerative disease causing the progressive destruction of articular cartilage; however, the aetiology has not yet been elucidated. Circular RNAs (circRNAs) are reportedly involved in cartilage degeneration and OA development. In the present study, we identified that circNFIX regulates chondrogenesis and cartilage homeostasis. Materials and Methods: Microarray analysis was performed to explore circRNA expression during the chondrogenic differentiation of human adipose‐drived stem cells (hADSCs). CircNFIX expression was determined using quantitative reverse transcription‐polymerase chain reaction and in situ hybridization. Gain‐ and loss‐of‐function assays were performed to validate the role of circNFIX in cartilage homeostasis. RNA pull‐down, Argonaute2‐RNA immunoprecipitation and luciferase reporter assays were performed to evaluate the interactions among circNFIX, miR758‐3p and KDM6A. Results: CircNFIX expression was upregulated in the early and middle stages, whereas downregulated in the late stage of hADSC chondrogenesis. CircNFIX inhibition attenuated hADSC chondrogenesis. CircNFIX was remarkably downregulated in OA samples, circNFIX overexpression protected against chondrocyte degradation and alleviated OA progression in the destabilization of the medial meniscus OA model. Mechanistically, circNFIX acted as a sponge of miR758‐3p and played a role in the chondrogenesis and chondrocyte degeneration by targeting the miR‐758‐3p/KDM6A axis. Conclusions: Our results revealed a key role of circNFIX in chondrogenesis and cartilage homeostasis, which may provide a potential therapeutic strategy for OA treatment. [ABSTRACT FROM AUTHOR]

Chronic inflammation and infection in the tissue surrounding implants after total joint replacement is closely associated with the innate immune response to surgical implants. Wear particles are known to increase apoptosis and impair the innate immunity in macrophages, which can cause immunosuppression around the implants. Excessive autophagy can induce apoptosis. However, the link between autophagy and apoptosis in macrophages during chronic inflammation and infection remains unknown. In this study, we investigated the autophagy and apoptosis induced by titanium particles in RAW264.7 macrophages, and in the interface membrane of patients with late‐onset periprosthetic joint infection (PJI). We found that titanium particles stimulated autophagy and apoptosis in macrophages. Inhibition of autophagy significantly reduced titanium particle‐induced apoptosis in macrophages, which may be related to the PI3K/Akt signaling pathway. The secretion of inflammatory factors, such as IL‐1β, IL‐6, and TNF‐α, decreased after inhibition of autophagy in titanium particle‐stimulated macrophages, which may be caused by immune dysfunction due to titanium particle‐induced autophagy and apoptosis in macrophages. Furthermore, our in vivo mouse calvarial model also showed that autophagy inhibitors lowered the rate of cell apoptosis. Our findings indicate that wear particle‐induced apoptosis may be caused by enhanced autophagy in macrophages, which could potentially impair the local innate immunity in periprosthetic tissues and could be a risk factor for PJI. Based on these results, autophagy modulators may act as a new therapeutic option for PJI. [ABSTRACT FROM AUTHOR]

[Cu(ttpy‐tpp)Br2]Br (abbreviated as CTB) is a novel mitochondrion‐targeting copper(II) complex synthesized by our research group, which contains tri‐phenyl‐phosphonium (TPP) groups as its lipophilic property. In this study, we explored how CTB affects mitochondrial functions and exerts its anti‐tumour activity. Multiple functional and molecular analyses including Seahorse XF Bioanalyzer Platform, Western blot, immunofluorescence analysis, co‐immunoprecipitation and transmission electron microscopy were used to elucidate the underlying mechanisms. Human hepatoma cells were subcutaneously injected into right armpit of male nude mice for evaluating the effects of CTB in vivo. We discovered that CTB inhibited aerobic glycolysis and cell acidification by impairing the activity of HK2 in hepatoma cells, accompanied by dissociation of HK2 from mitochondria. The modification of HK2 not only led to the complete dissipation of mitochondrial membrane potential (MMP) but also promoted the opening of mitochondrial permeability transition pore (mPTP), contributing to the activation of mitophagy. In addition, CTB co‐ordinately promoted dynamin‐related protein 1 (Drp1) recruitment in mitochondria to induce mitochondrial fission. Our findings established a previously unrecognized role for copper complex in aerobic glycolysis of tumour cells, revealing the interaction between mitochondrial HK2‐mediated mitophagy and Drp1‐regulated mitochondrial fission. [ABSTRACT FROM AUTHOR]

MicroRNAs play critical roles in the pathogenesis of osteoarthritis, the most common chronic degenerative joint disease. Exosomes derived from miR‐95‐5p‐overexpressing primary chondrocytes (AC‐miR‐95‐5p) may be effective in treating osteoarthritis. Increased expression of HDAC2/8 occurs in the tissues and chondrocyte‐secreted exosomes of patients with osteoarthritis and mediates cartilage‐specific gene expression in chondrocytes. We have been suggested that exosomes derived from AC‐miR‐95‐5p (AC‐miR‐95‐5p‐Exos) would enhance chondrogenesis and prevent the development of osteoarthritis by directly targeting HDAC2/8. Our in vitro experiments showed that miR‐95‐5p expression was significantly lower in osteoarthritic chondrocyte‐secreted exosomes than in normal cartilage. Treatment with AC‐miR‐95‐5p‐Exos promoted cartilage development and cartilage matrix expression in mesenchymal stem cells induced to undergo chondrogenesis and chondrocytes, respectively. In contrast, co‐culture with exosomes derived from chondrocytes transfected with an antisense inhibitor of miR‐95‐5p (AC‐anti‐miR‐95‐5p‐Exos) prevented chondrogenic differentiation and reduced cartilage matrix synthesis by enhancing the expression of HDAC2/8. MiR‐95‐5p suppressed the activity of reporter constructs containing the 3ʹ‐untranslated region of HDAC2/8, inhibited HDAC2/8 expression and promoted cartilage matrix expression. Our results suggest that AC‐miR‐95‐5p‐Exos regulate cartilage development and homoeostasis by directly targeting HDAC2/8. Thus, AC‐miR‐95‐5p‐Exos may act as an HDAC2/8 inhibitor and exhibit potential as a disease‐modifying osteoarthritis drug. [ABSTRACT FROM AUTHOR]

The expression of miR-455-3p has been shown to be up-regulated in chondrogenesis of mesenchymal stem cell, but its role in different stages during chondrogenesis remains unknown. Here, we show that miR-455-3p is increased in ATDC5 cells from 0 d to 21 d, but rapidly decreases at 28 d, and a similar expression kinetic is detected in the development of mouse embryos. We show that miR-455-3p functions as an activator for early chondrogenic differentiation, most likely by inhibiting the expression of Runt-related transcription factor 2 (Runx2) as indicated by luciferase reporter assays. In conclusion, miR-455-3p may activate early chondrogenesis by directly targeting Runx2. [ABSTRACT FROM AUTHOR]

Cartilage generation and degradation are regulated by miRNAs. Our previous study has shown altered expression of miR-193b in chondrogenic human adipose-derived mesenchymal stem cells (hADSCs). In the current study, we investigated the role of miR-193b in chondrogenesis and cartilage degradation. Luciferase reporter assays showed that miR-193b targeted seed sequences of the TGFB2 and TGFBR3 3′-UTRs. MiR-193b suppressed the expression of early chondrogenic markers in chondrogenic ATDC5 cells, and TNF-alpha expression in IL-1b-induced PMCs. In conclusion, MiR-193b may inhibit early chondrogenesis by targeting TGFB2 and TGFBR3, and may regulate inflammation by repressing TNF-alpha expression in inflamed chondrocytes. [ABSTRACT FROM AUTHOR]

Application of chondrogenic growth factors is a routine strategy to induce chondrogenesis of hMSCs, but they have economic and safety problems in the long term. It is expected that scaffold material itself could play an important role in chondrogenesis of hMSCs. In this study we tested whether a novel tricalcium phosphate-collagen-hyaluronan scaffold (TCP-COL-HA) had inherent chondro-inductive capacity for chondrogenesis of both ATDC5 and hMSCs without any exogenous growth factors in vitro. hMSCs and ATDC5 were seeded onto TCP-COL-HA scaffolds and cultured in basal medium for 3 weeks to investigate whether the TCP-COL-HA scaffold itself had differentiation-inductive capacity in basal culture. With hMSCs-seeded scaffold in chondrogenic medium (including TGF-β1) as positive control, we then compared the chondrogenic induction of TCP-COL-HA in basal culture and in chondrogenic culture. The chondrogenic differentiation was evaluated by sulfated glycosaminoglycans (GAGs) quantification, type II collagen immunohistochemistry, and RT-PCR. Mechanical strength was evaluated by compression test and the cell death rate of hMSCs was assessed with TUNEL assay. The results showed TCP-COL-HA scaffold itself could efficiently induce chondrogenic differentiation of both ATDC5 and hMSCs after 3 weeks in basal culture. The accumulation of GAGs and the expression of chondrocyte marker genes were all significantly increased. In addition, hMSCs-seeded scaffold showed a significantly higher mechanical strength after 3 weeks in basal culture. The chondrogenic induction of TCP-COL-HA scaffolds in basal medium were almost similar to that in chondrogenic medium on hMSCs. The chondrogenesis-inducing capacity of TCP-COL-HA scaffold might help to improve cartilage tissue engineering with economic and safe benefits. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2725-2735, 2014. [ABSTRACT FROM AUTHOR]

Toll-like receptors (TLRs) recognizing pathogen-associated molecular patterns (PAMP) play a role in local immunity and participate in implant-associated loosening. TLRs-mediated signaling is regulated by interleukin-1 receptor-associated kinase-M (IRAK-M). Our previous studies have proved that IRAK-M is induced by wear particles in macrophages from periprosthetic tissues. In this study, the IRAK-M-related mechanisms were further explored by lipopolysaccharide (LPS) and/or titanium (Ti) particles stimulations and small interfering RNAs (siRNAs). The protein level of IRAK-M was studied using western blotting and tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) levels were measured using ELISA. Results showed that in RAW264.7 cells stimulated by LPS after Ti particle pre-exposure, IRAK-M was slightly changed, compared with LPS stimulation. And levels of TNF-α and IL-1β in cultures stimulated by LPS first after Ti particle pre-exposure were lower than in the other two groups which were stimulated by LPS with or without Ti particles ( p < 0.001), whereas there were no statistic differences between the later two ( p > 0.05). The cytokines were lowest in Ti particles alone stimulation. After siRNAs silenced, IRAK-M-deficient cells exhibited increased expression of the cytokines in LPS stimulation after Ti particle pre-exposure and when stimulated with Ti particles alone. Our findings suggest that debris-induced IRAK-M decreases foreign body reactions, but at the same time, the over-expression of IRAK-M may also be detrimental on local intrusion of PAMPs or bacteria, negatively regulates the LPS-induced and TLRs-mediated inflammation and results in immunosuppression in periprosthetic tissue, which may predispose to implant-associated infections. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 101A: 733-739, 2013. [ABSTRACT FROM AUTHOR]

The most common long-term complication of joint arthroplasty is loosening, which is mediated by chronic inflammatory cytokines produced by macrophages stimulated by implant-derived debris and eventually bacterial components adherent to such debris. In this study, antiinflammatory interleukin-1 receptor-associated kinase-M (IRAK-M) was studied in macrophages in interface membranes in vivo using immunohistochemical staining and in titanium particle-stimulated macrophages in vitro using reverse transcriptase-polymerase chain reaction. Results show that the interface membranes of septically and aseptically loosened prosthesis express more IRAK-M protein than control membranes from osteoarthritic patient and that IRAK-M mRNA-levels increase upon particle stimulation. These findings suggest that, the upregulation of IRAK-M in macrophages is involved in the local immunosuppression around implants, and may contribute to septic and aseptic implant loosening. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012. [ABSTRACT FROM AUTHOR]