PurposeThis review aims to elucidate the mechanisms underlying chondrocyte senescence in osteoarthritis (OA) from 4 core perspectives: extracellular inflammation, mechanical overload and stress, intracellular metabolic and signaling dysregulation, and genetics-related alterations. It further summarizes emerging therapeutic strategies targeting chondrocyte senescence to address the unmet clinical need for disease-modifying OA interventions.FindingsAccumulating evidence indicates that chondrocyte senescence drives OA progression through multiple interconnected mechanisms. These include amplification of inflammation and extracellular matrix degradation via the senescence-associated secretory phenotype (SASP), disruption of anabolic-catabolic homeostasis, dysregulation of mechanotransduction pathways under excessive mechanical load, and reshaping of intracellular metabolism and redox balance. Additional contributing mechanisms involve epigenetic dysregulation, non-coding RNA-mediated gene modulation, and impaired autophagy. Therapeutic approaches under preclinical or clinical investigation encompass senolytic and senomorphic agents, chondroprotective biological materials, genetic or RNA-based interventions, as well as strategies targeting SASP modulation and extracellular microenvironment repair.ConclusionsChondrocyte senescence serves as a central convergent mechanism in OA pathogenesis and a promising target for disease-modifying therapies. Advances in mechanistic understanding and senescence-targeted interventions offer new avenues for translational innovation, though critical challenges related to specificity, safety, and long-term efficacy require further resolution.

BACKGROUND:Mitochondrial dysfunction induces chondrocyte senescence, thereby precipitating articular cartilage (AC) degeneration in the pathogenesis of osteoarthritis (OA). Although the transfer of mitochondria from mesenchymal stem cells (MSCs) to host cells and their potential protective role have been demonstrated, whether MSCs can alleviate chondrocyte mitochondrial dysfunction or reverse OA progression remains unclear. METHODS:A mitochondrial tracer was used to investigate the transfer of mitochondria-rich extracellular vesicles (MEV) derived from the culture supernatant of human synovial fluid-derived mesenchymal stem cells (hSF-MSCs). Human articular chondrocytes (hACs) impaired by oxidative stress co-incubated with MEV were used for experimental research in vitro. Healthy hACs and stressed hACs were cultured separately acting as the control groups. The MEV was injected into the OA rats' knee joint serving as experimental group. Healthy and OA rats were served as the control groups. Quantitative reverse transcription polymerase chain reaction (qRT-PCR), western blot (WB), enzyme- linked immunosorbent assay (ELISA), flow cytometry (FC), immunofluorescence (IF), fluorescence spectrophotometer (FS), immunohistochemistry (IHC) and other methods are used to analyze the effect of MEV on hACs and OA progression. RESULTS:MEV derived from hSF-MSCs could transfer into hACs. Compared to the negative control group, co-incubation with MEV resulted in a significant down-regulation of oxidative stress markers and senescence-associated proteins in hACs, while improved mitochondrial function of hACs. Moreover, the MEV could traverse the dense interstitial layer and migrate towards the deeper cartilage, while intra-articular injection of MEV could effectively attenuate AC degeneration. CONCLUSION:The transfer of MEV derived from hSF-MSCs represents a promising strategy for safeguarding AC, thereby offering a potential avenue and mechanism for the treatment of OA.

Background:Several traditional dressings may have limitation in treating wounds. A novel chitosan-based dressing designed for improved hemostasis, moisture, and sealing shows promise in wound healing. However, its efficacy and safety are yet to be sufficiently verified in patients. Methods:This randomized controlled trial enrolled 40 patients suffering from acute skin wounds in the limbs from 12/2022 to 12/2023. They were randomly divided into two groups (20 vs. 20) and received regular treatments in the Shenzhen Second People's Hospital. The experimental group was treated with chitosan-based liquid dressing, whereas the control group was treated with traditional dressing with recombinant human epidermal growth factor (rhEGF). The therapeutic effects (scar area and pigment deposition), adverse events, visual analogue scale (VAS), healing time, cost, and the patient and observer scar assessment scale (POSAS) were evaluated on days 0, 7, 14, and 28. Results:No adverse events were observed throughout the trial. On day 28, effective rate between groups were not statistically significant between the groups (70% vs. 85%, p = 0.256). Other parameters that were not significant included VAS (5.10 ± 1.62 vs. 6.35 ± 2.39, p = 0.06), healing time (8.45 ± 4.26 vs. 8.60 ± 5.44 days, p = 0.923), and cost (49.00 ± 22.48 vs. 57.40 ± 27.59, p = 0.298). However, on day 28, the patient- and observer-reported SAS of the chitosan (CS) group was significantly lower than that of the rhEGF group (12.00 vs. 9.50, z = 2.477, p = 0.013; 18.50 vs. 12.50, z = 2.209, p = 0.026; respectively), and the total POSAS (30.50 vs. 22.00, z = 2.374, p = 0.017). Conclusion:Compared to rhEGF, the CS-based liquid dressing showed reliable safety and equivalent performance in treating acute limb skin wounds, as revealed by improvements in healing time and rate, pain relief, and costs. Moreover, liquid dressing significantly reduced scar formation, indicating its potential in wound therapy.

Osteoarthritis (OA) is a chronic joint disease characterized by articular cartilage degeneration, secondary bone hyperplasia, inadequate extracellular matrix synthesis and degeneration of articular cartilage. Mesenchymal stem cells (MSCs) can self-renew and undergo multidirectional differentiation; they can differentiate into chondrocytes. Aging MSCs have a weakened ability to differentiate, and release various pro-inflammatory cytokines, which may contribute to OA progression; the other mechanism contributing to OA is epigenetic regulation (for instance, DNA methylation, histone modification and regulation of non-coding RNA). Owing to the self-renewal and differentiation ability of MSCs, various MSC-based exogenous cell therapies have been developed to treat OA. The efficacy of MSC-based therapy is mainly attributed to cytokines, growth factors and the paracrine effect of exosomes. Recently, extensive studies have been conducted on MSC-derived exosomes. Exosomes from MSCs can deliver a variety of DNA, RNA, proteins and lipids, thereby facilitating MSC migration and cartilage repair. Therefore, MSC-derived exosomes are considered a promising therapy for OA. The present review summarized the association between MSC aging and OA in terms of genetics and epigenetics, and characteristics of MSC-derived exosomes, and the mechanism to alleviate OA cartilage damage.

Contactin-2 (CNTN2), an immunoglobulin cell adhesion molecule (IgCAM) expressed on the neural cell surface, regulates the formation of myelin sheaths, facilitates communication between neurons and axoglial cells, and coordinates the migration of neural cells. However, the assembly of full-length CNTN2 is still not fully elucidated. Here, we found that the full-length human CNTN2 forms a concentration-dependent homodimer. We further determined the cryo-EM structures of the full-length CNTN2, revealing a novel bowknot-shaped scaffold constituted of the Ig1-6 repeats from two protomers, with the flexible ribbon-like FNIII repeats extending outward in opposite directions. The Ig1-6 domains, rather than the previously proposed Ig1-4 domains, have an indispensable role in mediating CNTN2-dependent cell adhesion and clustering. Moreover, structure-guided mutagenesis analyses supported the idea that CNTN2 homodimerization observed in our structure is essential for cell adhesion. Our findings offer novel insights into the mechanism through which CNTN2 forms a homodimer to maintain cell-cell contacts in the nervous system.

ClC-2 transports chloride ions across plasma membranes and plays critical roles in cellular homeostasis. Its dysfunction is involved in diseases including leukodystrophy and primary aldosteronism. AK-42 was recently reported as a specific inhibitor of ClC-2. However, experimental structures are still missing to decipher its inhibition mechanism. Here, we present cryo-EM structures of apo ClC-2 and its complex with AK-42, both at 3.5 Å resolution. Residues S162, E205 and Y553 are involved in chloride binding and contribute to the ion selectivity. The side-chain of the gating glutamate E205 occupies the putative central chloride-binding site, indicating that our structure represents a closed state. Structural analysis, molecular dynamics and electrophysiological recordings identify key residues to interact with AK-42. Several AK-42 interacting residues are present in ClC-2 but not in other ClCs, providing a possible explanation for AK-42 specificity. Taken together, our results experimentally reveal the potential inhibition mechanism of ClC-2 inhibitor AK-42.

Pannexin 2 (Panx2) is a large-pore ATP-permeable channel with critical roles in various physiological processes, such as the inflammatory response, energy production and apoptosis. Its dysfunction is related to numerous pathological conditions including ischemic brain injury, glioma and glioblastoma multiforme. However, the working mechanism of Panx2 remains unclear. Here, we present the cryo-electron microscopy structure of human Panx2 at a resolution of 3.4 Å. Panx2 structure assembles as a heptamer, forming an exceptionally wide channel pore across the transmembrane and intracellular domains, which is compatible with ATP permeation. Comparing Panx2 with Panx1 structures in different states reveals that the Panx2 structure corresponds to an open channel state. A ring of seven arginine residues located at the extracellular entrance forms the narrowest site of the channel, which serves as the critical molecular filter controlling the permeation of substrate molecules. This is further verified by molecular dynamics simulations and ATP release assays. Our studies reveal the architecture of the Panx2 channel and provide insights into the molecular mechanism of its channel gating.

Drug discovery is a crucial part of human healthcare and has dramatically benefited human lifespan and life quality in recent centuries, however, it is usually time- and effort-consuming. Structural biology has been demonstrated as a powerful tool to accelerate drug development. Among different techniques, cryo-electron microscopy (cryo-EM) is emerging as the mainstream of structure determination of biomacromolecules in the past decade and has received increasing attention from the pharmaceutical industry. Although cryo-EM still has limitations in resolution, speed and throughput, a growing number of innovative drugs are being developed with the help of cryo-EM. Here, we aim to provide an overview of how cryo-EM techniques are applied to facilitate drug discovery. The development and typical workflow of cryo-EM technique will be briefly introduced, followed by its specific applications in structure-based drug design, fragment-based drug discovery, proteolysis targeting chimeras, antibody drug development and drug repurposing. Besides cryo-EM, drug discovery innovation usually involves other state-of-the-art techniques such as artificial intelligence (AI), which is increasingly active in diverse areas. The combination of cryo-EM and AI provides an opportunity to minimize limitations of cryo-EM such as automation, throughput and interpretation of medium-resolution maps, and tends to be the new direction of future development of cryo-EM. The rapid development of cryo-EM will make it as an indispensable part of modern drug discovery.

[This corrects the article DOI: 10.2147/IJN.S394666.].

Background: Calf muscle venous thrombosis (CMVT) is among the most important medical complications after hip surgery. CMVT has been known for many years, but many opinions about the incidence and risk factors of CMVT are still controversial. The objective of this retrospective study was to investigate the incidence and associated risk factors of postoperative CMVT in patients with hip fractures. Methods: Patients with hip fractures from January 2020 to April 2022 (n = 320) at Shenzhen Second People’s Hospital were recruited in this study. The personal characteristics and clinical data of CMVT and no-CMVT patients were compared and analyzed. Binary logistic regression analyses were performed to identify potential risk factors of CMVT in patients with hip fractures. Finally we performed a receiver operating characteristic (ROC) curve analysis to compare the diagnostic values of different variables. Results: The overall incidence of new-onset CMVT in patients with hip fractures was 18.75% (60 of 320). Among the 60 CMVT patients, 70% (42 of 60) were diagnosed with femoral neck fractures, 28.3% (17 of 60) with intertrochanteric fractures, and 1.7% (1 of 60) with subtrochanteric fractures. No pulmonary embolism (PE) occurred. High preoperative D-dimer (OR = 1.002, 95%CI 0.97–1.03), sex (OR = 1.22, 95%CI 0.51–2.96), the caprini score (OR = 2.32, 95%CI 1.05–5.16) and the waterlow score (OR = 1.077, 95%CI 0.35–3.36) significantly increased the risk of developing postoperative new-onset CMVT. Conclusions: CMVT has become a common clinical disease, and its harm should not be underestimated. Our study found that D-dimer, sex, the caprini score and the waterlow score were independent risk factors for postoperative CMVT. According to our clinical work, we should pay attention to identifying the risk factors of CMVT formation and targeted intervention measures to prevent new-onset CMVT.

Periodontal disease is one of the most common oral diseases with the highest incidence world-wide. In particular, the treatment of periodontal bone defects caused by periodontitis has attracted extensive attention. Guided bone regeneration (GBR) has been recognized as advanced treatment techniques for periodontal bone defects. GBR technique relies on the application of barrier membranes to protect the bone defects. The commonly used GBR membranes are resorbable and non-resorbable. Resorbable GBR membranes are divided into natural polymer resorbable membranes and synthetic polymer resorbable membranes. Each has its advantages and disadvantages. The current research focuses on exploring and improving its preparation and application. This review summarizes the recent literature on the application of GBR membranes to promote the regeneration of periodontal bone defects, elaborates on GBR development strategies, specific applications, and the progress of inducing periodontal bone regeneration to provide a theoretical basis and ideas for the future application of GBR membranes to promote the repair of periodontal bone defects.

[This retracts the article DOI: 10.3892/ol.2018.7994.].

There are debates in residual end preservation technique in anterior cruciate ligament reconstruction whether it would promote the bone-tendon healing, knee proprioception recovery, vascularization of synovial membrane and transplanted ligament. This article retrieved the literatures from January 2018 to September 2022, and provided induction, summary and discussion of the influence of residual preservation in anterior cruciate ligament reconstruction on bone tunnel, proprioception recovery, vascularization of synovial membrane and transplanted ligament, and early knee function recovery. Preservation residual anterior cruciate ligament reconstruction shows advantages in promoting early tendon bone healing and vascularization of synovial membrane and transplanted ligament, and is also conducive to the recovery of proprioception, which in turn accelerate the knee joint function recovery. Clinical doctors should base on the residual type of the anterior cruciate ligament rupture in patients, for patients who meet the conditions of residual reserves, surgeons shall retaine the tissue as far as possible during anterior cruciate ligament reconstruction.

Full-thickness skin wounds are have continued to be reconstructive challenges in dermal and skin appendage regeneration, and skin substitutes are promising tools for addressing these reconstructive procedures. Herein, the one-step fabrication of a cell sheet integrated with a biomimetic hydrogel as a tissue engineered skin for skin wound healing generated in one step is introduced. Briefly, cell sheets with rich extracellular matrix, high cell density, and good cell connections were integrated with biomimetic hydrogel to fabricate gel + human skin fibroblasts (HSFs) sheets and gel + human umbilical vein endothelial cells (HUVECs) sheets in one step for assembly as a cell sheet-laden hydrogel (CSH). The designed biomimetic hydrogel formed with UV crosslinking and ionic crosslinking exhibited unique properties due to the photo-generated aldehyde groups, which were suitable for integrating into the cell sheet, and ionic crosslinking reduced the adhesive force toward the substrate. These properties allowed the gel + cell sheet film to be easily released from the substrate. The cells in the harvested cell sheet maintained excellent viability, proliferation, and definite migration abilities inside the hydrogel. Moreover, the CSH was implanted into a full-thickness skin defects to construct a required dermal matrix and cell microenvironment. The wound closure rate reached 60.00 ± 6.26% on the 2nd day, accelerating mature granulation and dermis formation with skin appendages after 14 days. This project can provide distinct guidance and strategies for the complete repair and regeneration of full-thickness skin defects, and provides a material with great potential for tissue regeneration in clinical applications.

Introduction: The increasing use of gold nanoparticles (Au NPs) in the medical field has raised concerns about the potential adverse effect of Au NPs exposure. However, it is difficult to assess the health risks of Au NPs exposure at the individual organ level using current measurement techniques.Methods: The physical and chemical properties of Au NPs were characterized by transmission electron microscope (TEM), Fourier transform infrared (FTIR), and zeta sizer. The RNA-seq data of Au NPs-exposed worms were analyzed. The food intake was measured by liquid culture and Pharyngeal pumping rate. The function of the smell and taste neurons was evaluated by the chemotaxis and avoidance assay. The activation of ASE neurons was analyzed by calcium imaging. The gene expression of ins-22 and egl-19 was obtained from the C. elegans single cell RNA-seq databases.Results: Our data analysis indicated that 62.8% of the significantly altered genes were functional in the nervous system. Notably, developmental stage analysis demonstrated that exposure to Au NPs interfered with animal development by regulating foraging behavior. Also, our chemotaxis results showed that exposure to Au NPs reduced the sensation of C. elegans to NaCl, which was consistent with the decrease in calcium transit of ASEL. Further studies confirmed that the reduced calcium transit was dependent on voltage-gated calcium channel EGL-19. The neuropeptide INS-22 was partially involved in Au NPs-induced NaCl sensation defect. Therefore, we proposed that Au NPs reduced the calcium transit in the ASEL neuron through egl-19-dependent calcium channels. It was partially regulated by the DAF-16 targeting neuropeptide INS-22.Discussion: Our results demonstrate that Au NPs affect food sensation by reducing the calcium transit in ASEL neurons, which further leads to reduced pharynx pumping and feeding defects. The toxicology studies of Au NPs from worms have great potential to guide the usage of Au NPs in the medical field such as targeted drug delivery.

Objective To construct the recombinant adeno-associated virus（rAAV） vector which carrying nuclear location signal core binding factor beta（NLS-CBFβ）, and induce chondrogenic differentiation of articular fluid mesenchymal stem cells in vitro. Methods pAAV-NLS-CBFβ-RFP expression plasmid was constructed by combining adeno-associated virus vector with NLS-CBFβ gene using molecular biology method. pAAV-NLS-CBFβ-RFP expression plasmid, pAAV-RC and pAAV-Helper plasmid were co-transfected into the AAV-293 cells by PEI transfection method, recombinant adeno-associated virus rAAV-NLS-CBFβ-RFP carrying CBFβ was packed and produced, the virus was further infected with human synovial fluid mesenchymal stem cells, the expression level of CBFβ gene in the cells were detected by real-time fluorescent quantitative polymerase chain reaction（qRT-PCR）. Results pAAV-NLS-CBFβ-RFP expression plasmid expression plasmid was successfully constructed and was verified by double digestion and DNA sequencing, and the expression of red fluorescent protein in AAV-293 cells indicated that co-transfection was successful. After the recombinant adeno-associated virus rAAV-CBFβ-RFP was infected with human joint fluid mesenchymal stem cells, it can significantly increase the expression level of CBFβ gene in cells. Conclusion The recombinant adeno-associated virus carrying NLS-CBFβ was successfully packaged and effectively transfected and expressed in human joint fluid mesenchymal stem cells, which provided an experimental basis for further research on the chondrogenic differentiation of mesenchymal stem cells induced by rAAV-NLS-CBFβ.

Leucine-rich repeat-containing protein 8 A (LRRC8A) protein is a critical member of volume-regulated anion channels. It plays a critical roles in the regulation of cellular volume and involves in the development of diseases like osteoarthritis. Screening of lead compounds to modulate its function may provide potential therapeutics of related diseases. Here, we employ virtual screening techniques and molecular dynamics (MD) simulation to screen potential inhibitors against LRRC8A. LRRC8A was regarded as the drug target to investigate potential compounds from the ZINC15 database via molecular docking. The final compound was selected among the top 10 Autodock Vina score (-8.8 Kcal/mol) with the ZINC ID ZINC000018195627 after druggability prediction. The docked complex from the virtual screening was subjected to MD simulation to analyze the stability of the LRRC8A protein-ligand complex, with parameters including root mean square deviation, root mean square fluctuation and radius of gyration. Molecular Mechanics/Poisson-Boltzmann Surface Area (MM/PBSA) method was further employed to predict the binding free energies from MD simulation trajectory. Our study provides insightful analysis for the potential compound to modulate LRRC8A and lay the foundation of therapeutics development against osteoarthritis.Communicated by Ramaswamy H. Sarma