Bionic ECM scaffolds for directional articular hyaline cartilage regeneration and long-term homeostasis maintenance

Cartilage defects play a key role in osteoarthritis, causing functional impairment as the disease progresses. Microfracture surgery is commonly used to treat articular cartilage defects, providing early pain relief and functional improvement. However, the blood clot formed during the procedure differs from the natural cartilage microenvironment, hindering hyaline cartilage formation and promoting fibrocartilage, which limits long-term outcomes. This study proposes combining a bionic flexible extracellular matrix (ECM) scaffold with microfracture surgery as a treatment for cartilage defects. By filling the microfracture site with the scaffold and thermosensitive agarose gel, we can anchor BMSCs leaking from the bone marrow while creating a 3D microenvironment that regulates stem cell differentiation. Our results show that the scaffold's mechanical strength is comparable to that of hyaline cartilage, offering excellent biomimetic properties and biocompatibility. In vitro, BMSCs migrating into the scaffold exhibited a survival rate of nearly 90 % by day 2, significantly higher than the 25 % survival rate in the control agarose gel group, with cells observed anchoring around the scaffold. In vivo, stem cells anchored to the scaffold successfully differentiated into articular hyaline cartilage, driven by the combined effects of the scaffold's physical structure and its contained cytokines. The generated hyaline cartilage maintains homeostasis over time, reducing the risk of fibrocartilage formation. This strategy addresses a key limitation of microfracture surgery, where regenerated cartilage is often fibrocartilage, offering a promising new approach for cartilage repair.

Periprosthetic osteolysis: Mechanisms and potential treatment strategies

Periprosthetic osteolysis is a common bone-related disorder that often occurs after total hip arthroplasty. The implants can cause damage to bone and bone-related cells due to mechanical stress and micromotions, resulting in the generation of a large number of wear particles. These wear particles trigger inflammation and oxidative stress in the surrounding tissues, disrupting the delicate balance maintained by osteoblasts and osteoclasts, ultimately leading to bone loss around the implant. Clinical investigations have demonstrated that Epimedium prenylflavonoids, miR-19a-3p, stem cell-derived exosomes, and certain non-PPO category pharmaceuticals have regulatory effects on bone homeostasis through distinct molecular pathways. Notably, this phenomenon reflects inherent biological rationality rather than stochastic occurrence. Extensive research has revealed that multiple natural compounds, non-coding RNAs, exosomes, and non-PPO therapeutics not only exert modulatory influences on critical pathophysiological processes including inflammatory cascades, oxidative stress responses, and tissue regeneration mechanisms, but also effectively regulate bone-related cellular functions to inhibit PPO progression. Therefore, this review comprehensively and systematically summarizes the main pathogenic mechanisms of periprosthetic osteolysis. Furthermore, it delves deeper into the research progress on the applications of currently reported natural products, ncRNAs, exosomes, and non-PPO medications in the treatment of periprosthetic osteolysis. Based on this, we hope that this paper can provide new perspectives and references for the future development of drugs targeting periprosthetic osteolysis.

Pathophysiology of the Effects of Oxidative Stress on the Skeletal System

Reactive oxygen species (ROS) are molecules that are generated primarily during energy production in cells. ROS are involved in critical biological functions such as signal transduction; when the production of ROS is imbalanced, excessive ROS causes oxidative stress, and subsequent cellular damage. Oxidative stress is linked to numerous pathological disorders in major organs including the skeletal system. In an aging society, understanding the role of ROS in skeletal health is critical to developing preventative and therapeutic interventions. Oxidative stress causes defects in cellular differentiation, apoptosis, mitochondrial dysfunction, and inflammation. The effects of oxidative stress on the skeletal system have been implicated in the development of osteoporosis, knee osteoarthritis, and osteonecrosis by inhibiting bone remodeling, increasing osteoclast activity, and decreasing osteoblast function. ROS are also involved in many signaling pathways that regulate immune defense, cell proliferation, and inflammation. This underscores the importance of maintaining a balance between ROS and antioxidants to prevent oxidative stress and related diseases. Targeting ROS and oxidative stress mechanisms may offer new treatments for diseases affecting the skeletal system and other organs, potentially improving health outcomes, and extending healthy lifespans. This review highlights the significant impact of oxidative stress on skeletal health and explores potential preventative and therapeutic strategies to mitigate the adverse effects of ROS.

Recent advances in osteonecrosis of the femoral head: a focus on mesenchymal stem cells and adipocytes

Osteonecrosis of the femoral head (ONFH) is a debilitating orthopedic disease characterized by femoral head collapse and destruction of bone and articular cartilage, resulting in severe joint pain and loss of hip mobility. Bone marrow mesenchymal stem cells (BMSCs) exhibit multilineage differentiation potential, including osteoblasts, adipocytes, fibroblasts, chondrocytes, and neurocytes. The imbalance between osteogenesis and adipogenesis in BMSCs plays a critical role in ONFH pathogenesis. Factors such as alcohol consumption and glucocorticoid exposure promote adipogenic differentiation while inhibiting osteogenic differentiation, leading to excessive adipocyte accumulation, reduced bone formation, and vascular impairment. We highlight the molecular mechanisms underlying ONFH with a particular focus on the role of BMSCs and further discuss the involvement of adipocytes. Moreover, we suggest that the use of adipose-derived mesenchymal stem cells (ADMSCs) is a viable approach for stem cell therapy and may have immense potential in ONFH. Several signaling pathways, including the Wnt, TGFβ/BMP, and PI3K/AKT pathways, along with various RNAs and other regulators, govern the osteogenesis and adipogenesis of BMSCs. These signaling pathways target essential transcription factors, such as Runx2 for osteogenesis and PPARγ and C/EBPs for adipogenesis. Adipocytes and their secreted adipokines, including leptin and adiponectin, strongly influence ONFH progression. Emerging therapies involving ADMSCs show potential for promoting bone regeneration and neovascularization. Our review provides a comprehensive overview of the current understanding of ONFH mechanisms by focusing on mesenchymal stem cells and adipocytes and suggests future research directions for therapeutic interventions.

Focusing on ferroptosis in alveolar bone loss during periodontitis: From mechanisms to therapies

Periodontitis is an oral immunoinflammatory disease induced by bacterial infection. During periodontitis, the aggravating destruction of the alveolar bone can result in tooth movement and even tooth loss. Current conventional treatments for periodontitis primarily focus on infection control, but their effectiveness in halting and restoring alveolar bone destruction is limited. To identify additional therapeutic targets, researchers have been dedicated to investigating other pathological mechanisms underlying alveolar bone loss during periodontitis. Recently, findings indicate that ferroptosis plays a role in the development of periodontitis. Ferroptosis is a nonapoptotic type of cell death marked by iron accumulation and lipid peroxidation. Recent investigations have revealed the complex interplay of ferroptosis and inflammation. The positive feedback loop between ferroptosis and inflammation may significantly contribute to the exacerbation of alveolar bone loss. In light of the advancements in research within this field in recent years, this review intends to thoroughly summarize the processes by which ferroptosis aggravates alveolar bone loss during periodontitis, along with relevant ferroptosis-targeted therapeutic agents. By highlighting the latest advancements in this area, we hope this review will inspire researchers to develop novel therapeutic strategies for more effective inflammation control and regeneration of alveolar bone.

Optimal parameters and Biomechanical analysis of the lightbulb technique for osteonecrosis of the femoral head: a finite element analysis

BACKGROUND

The lightbulb technique (LBT) is a common surgical procedure for treating peri-collapse osteonecrosis of the femoral head (ONFH). However, the drilling parameters and biomechanics of the technique have not been analyzed. The aim of this study was to optimize the biomechanical stability of the LBT by finite element (FE) analysis to guide intraoperative and postoperative schemes.

METHODS

FE models were established based on computed tomography images of a healthy adult, including three different degrees of necrotic lesion (60°, 100°, 115°), drilling locations (points C and L) and diameters (1.0 cm, 1.5 cm). The stress of the drilling entrance area, superior and inferior edges of the femoral neck, and bone flap was evaluated under three different loads at 0.5 times body weight (0.5 BW, standing on two feet), 2.75 BW (standing on one foot), and 4 BW (walking with the middle foot on the ground).

RESULTS

The stress of the superior and inferior edges of femoral neck, entrance, and bone flap increased as drilling diameter increased. The maximum Von Mises stress of proximal femur does not exceed its yield strength with diameter of 1.0 cm, except for diameter of 1.5 cm. The stress of entrance area and bone flap cortex at point L were higher than those at point C with same diameter. Moreover, the stress of femoral neck and entrance area decreased as the range of lesions increased, except for bone flap cortex. Furthermore, the maximum Von Mises stress of proximal femur did not exceed its yield strength with patients standing on one or both feet and walking process (4BW) with drilling diameter of 1.0 cm at points C or L after surgery, except for diameter of 1.5 cm. Meanwhile, the angles reaching to the coronal plane and transverse plane of weight-bearing area through point L with diameter of 1.0 cm were smaller than those through point C.

CONCLUSIONS

The optimal parameters of LBT can be selected with a diameter of 1.0 cm at point L. Patients can load partial weight to stimulate the healing of the necrotic area after surgery, but avoid beyond middle foot weight during walking.

Shaking culture attenuates circadian rhythms in induced pluripotent stem cells during osteogenic differentiation through the TEAD-Fbxl3-CRY axis

Circadian rhythms, which synchronize cellular and organismal activities with the Earth's 24-hour light-dark cycle, are controlled by clock genes. These genes not only regulate metabolic and physiological processes but also influence osteogenesis. Despite extensive research on the genetic control of circadian rhythms, little is known about the mechanisms by which mechanical factors in the extracellular environment affect these rhythms during the osteogenic differentiation of induced pluripotent stem cells (iPSCs). Shaking culture, which promotes the formation of three-dimensional organoid-like constructs from iPSC embryoid bodies (iPSC-EBs), introduces distinct biomechanical forces compared with static adherent culture. This raises the question of how these forces affect the circadian gene expression during osteogenic differentiation. In this study, we investigated the effects of shaking cultures on the circadian rhythm of key clock genes (Clock, Bmal1, and Npas2) in iPSC-EBs. In the adherent culture, iPSC-EBs displayed rhythmic oscillations of the clock genes, which were attenuated in the shaking culture. RNA-seq analysis revealed that the yes-associated protein (YAP)-transcriptional enhanced associate domain (TEAD) transcriptional cascade was activated in the shaking culture. Further investigations using assay for transposase-accessible chromatin with sequencing and chromatin immunoprecipitation assays identified Fbxl3 as a direct target of this transcriptional cascade. Fbxl3 upregulation in the shaking culture enhanced the degradation of CRY proteins, which are essential components of the circadian feedback loop, thereby suppressing clock gene oscillations. In addition, treatment with verteporfin, a YAP-TEAD inhibitor, restored circadian gene oscillations and increased the expression of osteogenic markers in shaking culture. These findings highlight a novel mechanistic link between biomechanical cues and circadian regulation and offer potential insights for optimizing tissue engineering strategies in regenerative medicine.

Elevated levels of β C-terminal telopeptide of type 1 collagen and N-terminal mid-fragment of osteocalcin in patients with non-traumatic osteonecrosis of the femoral head

OBJECTIVE

To investigate the role of serum β C-terminal telopeptide of type 1 collagen (β-CTx) and N-terminal mid-fragment of osteocalcin (N-MID) concentration in non-traumatic osteonecrosis of the femoral head (NONFH).

MATERIALS AND METHODS

In this retrospective case-control study, serum β-CTx and N-MID levels were measured in 64 NONFH patients and 64 healthy controls. Propensity score matching (PSM) was used to balance the baseline characteristics of the two groups. The study was conducted at Linyi People's Hospital between January 2023 and February 2024. The primary outcomes included the differences in serum β-CTx and N-MID levels between the two groups, their correlations with clinical parameters, and their diagnostic performance for NONFH.

RESULTS

The serum concentration of β-CTx and N-MID was significantly higher in NONFH patients compared to healthy controls (β-CTx: 0.70 ± 0.30 ng/ml vs. 0.36 ± 0.16 ng/ml, P < 0.001; N-MID: 21.35 ± 8.24 ng/ml vs. 13.27 ± 3.87 ng/ml, P < 0.001). No significant differences were observed in serum β-CTx and N-MID levels among different etiological subgroups or ARCO stages. Pearson analysis revealed a positive correlation between serum β-CTx and N-MID levels, as well as β-CTx and pain duration. The ROC curve analysis showed that β-CTx had an AUC of 0.876 (95% CI 0.815-0.938) with a cut-off value of 0.505 ng/ml, sensitivity of 90.63%, and specificity of 76.56%. N-MID had an AUC of 0.860 (95% CI 0.797-0.924) with a cut-off value of 17.050 ng/ml, sensitivity of 84.38%, and specificity of 78.13%.

CONCLUSION

Serum β-CTx and N-MID levels are significantly elevated in patients with NONFH and may serve as potential biomarkers for the diagnosis of NONFH. Further studies with larger sample sizes are needed to validate these findings and explore their clinical applications.

Mitochondrial SLC25A10 promotes prostate cancer progression by inhibiting ferritinophagy

Prostate cancer (PCa) is one of the most common malignancies in men worldwide and remains a major cause of cancer-related mortality. Despite advances in early diagnosis and treatment, a significant proportion of patients eventually progress to advanced or treatment-resistant disease, highlighting the urgent need for novel therapeutic targets and strategies. In this study, we systematically analyzed transcriptomic data from The Cancer Genome Atlas (TCGA) and performed Venn analysis to identify genes associated with PCa progression. Among the intersecting candidates, SLC25A10, a mitochondrial carrier protein, emerged as a potential key regulator of ferroptosis. Further expression analyses revealed that SLC25A10 is significantly upregulated in PCa tissues and correlates with poor prognosis. Functional gain- and loss-of-function experiments demonstrated that SLC25A10 promotes tumor cell proliferation, migration, and invasion, while exacerbating mitochondrial dysfunction and impairing autophagic flux. Mechanistically, mass spectrometry and co-immunoprecipitation (Co-IP) assays confirmed a direct interaction between SLC25A10 and P62, implicating this interaction in the suppression of autophagy and the promotion of ferroptotic vulnerability. Moreover, disruption of the SLC25A10/p62/KEAP1/Nrf2 signaling axis reactivated autophagy and inhibited PCa cell growth. Collectively, our findings uncover a novel oncogenic role of SLC25A10 in PCa and suggest that targeting the SLC25A10-mediated regulatory network may offer a promising therapeutic avenue for patients with advanced prostate cancer.

Theranostics of osteoarthritis: Applications and prospects of precision targeting nanotechnology

Osteoarthritis (OA), a complex degenerative joint disease driven by cartilage degeneration, synovial inflammation, and subchondral bone remodeling, lacks effective disease-modifying therapies. Precision-targeted nanotechnology has emerged as a breakthrough strategy, offering enhanced drug delivery, reduced toxicity, and synergistic diagnostic-therapeutic capabilities. This review summarizes OA pathogenesis, focusing on dysregulated immune networks and self-perpetuating synovial microenvironmental interactions. We discuss advanced nanomedicine approaches, which leverage OA-specific pathological cues for localized treatment. Innovations in cytokine modulation, photothermal therapy, and integrated theranostics (photoacoustic/fluorescence imaging) are highlighted as transformative tools for real-time diagnosis and personalized intervention. Despite progress, challenges such as biocompatibility optimization, clinical translation barriers, OA heterogeneity necessitate further development of multifunctional nanocarriers and rationaldesigns. This work underscores the potential of nanotechnology to advance OA therapeutics, bridging preclinical innovation with clinical applicability in pharmaceutical sciences.

Association between sleep duration and hip fracture risk among the older adults: a cross-sectional study based on the NHANES

BACKGROUND

There has been sharp increase in the incidence of hip fractures (HFs) with the increasing aging globally. However, it remains ambiguous regarding the association between HF risk and sleep duration. This study intended to explore the association between sleep duration and HF risk among the older adults.

METHODS

The study assessed a cohort of 7,540 participants aged at least 60 years old using data from the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2010, as well as from 2013 to 2014. Two distinct groups of HF and non-HF were constructed on the basis of their history of HFs. Based on the self-reported sleep duration through a structured questionnaire, multivariate logistic regression analyses were conducted to examine the relationship between sleep duration and HF risk. In addition, restricted cubic splines (RCS) were used to assess linearity. The receiver operating characteristic (ROC) curve was used to explore the threshold of sleep duration for HF risk.

RESULTS

HFs were found in 129 patients among the 7,540 participants over 60 years of age with mean age of 70.17 ± 7.1 years. Significant differences in sleep duration were observed between the HF and non-HF groups (7.73 ± 1.68 h vs. 7.11 ± 1.42 h; p = 0.006). The multivariate analysis was adjusted for sociodemographic, behavioral lifestyle, and comorbidities. A 1-h increase in sleep duration was associated with higher odds of having prior hip fractures in unadjusted models [odds ratio (OR) = 1.36; 1.11, 1.67; p = 0.004], minimally adjusted models (OR = 1.23; 1.03, 1.48; p = 0.025), second adjusted models (OR = 1.22; 1.02,1.45; p = 0.026) and fully adjusted models (OR = 1.22; 1.03,1.45; p = 0.026). The relationship remained consistent across all four models, indicating the correlation of a longer sleep duration with an elevated HF risk. RCS analysis revealed a statistically linear relationship between sleep duration and HF risk (p-nonlinear = 0.244, p-overall < 0.01). In addition, the identified threshold of sleep duration linked to HF risk was determined to be 7.5 h among the older adults (AUC = 0.611).

CONCLUSION

This study suggests an linear association between sleep duration and the risk of HFs. Further research is needed to validate these findings and more clearly identify the clinical relevance of this potential relationship.

Multifunctional Janus Hydrogels: Surface Design Strategies for Next-Generation Clinical Solutions

Janus hydrogels, distinguished by their dual-sided structure with distinct physical and chemical properties, have garnered significant attention in the medical field, particularly for applications in drug delivery, tissue engineering, and wound healing. Their ability to simultaneously perform multiple functions, such as targeted drug release and biomimetic tissue interaction, positions them as a promising platform for advanced therapeutic strategies. The growing interest in these hydrogels is primarily driven by their multifunctionality and capacity to address complex biological needs. This review delves into the design, fabrication methods, and applications of Janus hydrogels in medicine, focusing on their potential to overcome the limitations of conventional therapies and providing a comprehensive overview of their role in contemporary biomedical applications.

Constructing a cross-tissue human knee single-cell atlas identified osteoarthritis reduces regenerative tissue stem cells while increasing inflammatory pain macrophages

Osteoarthritis (OA) affects the entire knee joint; however, cross-tissue molecular mechanisms are poorly understood due to a lack of comprehensive, integrated analysis. We constructed the first comprehensive single-cell RNA sequencing knee OA atlas from articular cartilage, meniscus, synovium, and subchondral bone which showed active communication between them. Healthy synovium and meniscus contain the largest populations of tissue stem cells (TSCs) and immune cells that are altered in OA. The regenerative TSCs expressing SDF1, SOX9, CD146, PDGFRB, and CD105 decrease during OA, whereas osteogenic TSCs expressing osteogenic differentiation-related factor NT5E (CD73) are increased. In OA, the balance between regenerative and osteogenic TSCs shifts in the OA state with an increased number of osteogenic TSCs. We also report an increased level of quadruple-positive inflammatory (IL1B-IL6-NOS2-TNF) and pain marker (P2RX7) specific macrophages in OA. Fibroblasts are enriched in OA-synovium and may contribute to fibrosis. Importantly, OA cartilage contains unique MMP13-producing detrimental chondrocytes along with RUNX2-producing chondrocytes that worsen OA pathophysiology. This atlas provides a novel avenue for potential therapeutic applications in human knee OA and other musculoskeletal diseases and injuries, targeting synovium and meniscus to intervene in OA-specific molecular and cellular alterations.

Variability in the classification, management, and outcome reporting for avascular necrosis of the femoral head: A systematic review

Introduction

There is no universally-utilized classification system for avascular necrosis of the femoral head (AVNFH), a debilitating condition that arises due to impaired blood supply resulting in cortical collapse. AVNFH may require early intervention to prevent irreversible damage leading to total hip arthroplasty. The purpose of this study is to assess the variability in classification, management, and outcomes reported in randomized controlled trials (RCTs) related to AVNFH.

Methods

PubMed, Embase, and Medline were queried for RCTs on the treatment of AVNFH (2010-2023). The number of patients, number of femoral heads, minimum follow-up, AVNFH classification system, treatment interventions, and outcome measures were extracted. Variability in classification, management approach, and reporting of outcomes was evaluated.

Results

A total of 30 RCTs met inclusion criteria, encompassing 1891 total patients. The mean number of patients in each study was 63 (SD = 41), with a mean minimum follow-up of 30 months (SD = 17). The Association Research Circulation Osseous classification system was utilized in 63 % (n = 19) of studies, Ficat and Arlet in 20 % (n = 6) of studies, Steinberg in 10 % (n = 3), Mitchell in 3 % (n = 1), and the China-Japan Friendship Hospital classifications in 3 % (n = 1). There were 61 treatment interventions, stratified into nine categories. Radiographic imaging was most commonly used to evaluate patients at follow-up.

Conclusion

There are a variety of classification systems, treatments, and outcome measures utilized in the literature to categorize and quantify AVNFH. The utilization of a universally-accepted classification system and standardized outcome reporting may help to ensure reproducibility and accuracy given a continued lack of consensus.

Ferroptosis-mediated immune responses in osteoporosis

Osteoporosis is a common systemic metabolic disease, characterized by decreased bone mass and susceptibility to fragility fractures, often associated with aging, menopause, genetics, and immunity. Ferroptosis plays an underestimated yet crucial role in the further impact of immune function changes on osteoporosis. Cell ferroptosis can induce alterations in immune function, subsequently influencing bone metabolism. In this context, this review summarizes several mechanisms of ferroptosis and introduces the latest insights on how ferroptosis regulates immune responses, exploring the interactions between ferroptosis and other mechanisms such as oxidative stress, inflammation, etc. This review elucidates potential treatment strategies for osteoporosis, emphasizing the promising potential of ferroptosis as an emerging target in the treatment of osteoporosis. In conclusion, preparations related to ferroptosis exhibit substantial clinical promise for enhancing bone mass restoration. The translational potential of this article: This review elucidates a nuanced conversation between the immune system and osteoporosis, with ferroptosis serving as the connecting link. These findings underscore the potential of ferroptosis inhibition as a therapeutic strategy for osteoporosis.

Nanoparticles targeting the central circadian clock: Potential applications for neurological disorders

Circadian rhythms and their involvement with various human diseases, including neurological disorders, have become an intense area of research for the development of new pharmacological treatments. The location of the circadian clock machinery in the central nervous system makes it challenging to reach molecular targets at therapeutic concentrations. In addition, a timely administration of the therapeutic agents is necessary to efficiently modulate the circadian clock. Thus, the use of nanoparticles in circadian clock dysfunctions may accelerate their clinical translation by addressing these two key challenges: enhancing brain penetration and/or enabling their formulation in chronodelivery systems. This review describes the implications of the circadian clock in neurological pathologies, reviews potential molecular targets and their modulators and suggests how the use of nanoparticle-based formulations could improve their clinical success. Finally, the potential integration of nanoparticles into chronopharmaceutical drug delivery systems will be described.

Versatile PLGA-Based Drug Delivery Systems for Tumor Immunotherapy

Tumor immunotherapy, which utilizes the immune system to fight cancer, represents a revolutionary method for cancer treatment. Poly (lactic-co-glycolic acid) (PLGA) copolymer has emerged as a promising material for tumor immunotherapy due to its biocompatibility, biodegradability, and versatility in drug delivery. By tuning the size, shape, and surface properties of PLGA-based systems, researchers have improved their ability to align with the requirements for diverse tumor immunotherapy modalities. In this review, the basic properties of the PLGA materials are first introduced and further the principal forms of the PLGA systems for controlled release are summarized and delivery applications are targeted. In addition, recent advances in the use of PLGA delivery systems are highlighted to enhance antitumor immune responses in terms of tumor vaccines, immunogenic cell death-mediated immune responses, tumor microenvironment modulation, and combination immunotherapies. Finally, prospects for the future research and clinical translation of PLGA materials are proposed.

A dual-function hyaluronic acid-encapsulated nanoplatform enables triple GSH depletion for apoptosis-ferroptosis synergistic oncotherapy

Ferroptosis has emerged as an alternative strategy to eradicate apoptosis-resistant tumor cells. However, the hypoxia and redox homeostasis in tumor microenvironment (TME) hinder effective ferroptosis induction. Herein, we report a multifunctional MnO2-nanoclusters-decorated Cu2+-doped mussel-inspired mesoporous polydopamine (CM) nanoplatform, which is further engineered by co-loading sorafenib (SRF) and indocyanine green (ICG) with the help of a cargo-loading and targeting-capable hyaluronic acid (HA) shell to obtain CMMSIH. Once accumulating in tumors, the MnO2 nanoclusters catalyze glutathione (GSH) oxidation and H2O2 decomposition to deplete intracellular GSH and alleviate hypoxia. The released SRF and exposed CM core are further devoted to inhibiting de novo GSH synthesis and scavenging endogenous GSH, respectively. This triple-modal GSH depletion inactivates intracellular glutathione peroxidase 4 (GPX4), thereby amplifying the potential for ferroptosis. Besides, the Cu2+-mediated fenton-like reaction and ICG-based photodynamic process generate abundant reactive oxygen species (ROS), further amplified by photothermal effect and MnO2-supplied oxygen of CMMSIH. This design synergistically achieves GPX4 inactivation, hypoxia alleviation and ROS accumulation, thus disrupting intracellular redox homeostasis and ultimately triggering the ferroptotic and apoptotic death of tumor cells. In vivo studies demonstrate that CMMSIH nanoplatform inhibits tumor growth without systemic toxicity, offering a promising multimodal strategy to overcome the limitations of TME.

Application of decellularized tissues in ear regeneration

More than 5 % of people worldwide suffer from hearing disorders. Ototoxic drugs, aging, exposure to loud sounds, rupture, subperichondrial hematoma, perichondritis, burns and frostbite and infections are the main causes of hearing loss, some of which can destroy the cartilage and lead to deformation. On the other hand, disorders of the external ear are diverse and can range from dangerous neoplasms to defects that are not acceptable from a cosmetic standpoint. These issues include injuries, blockages, dermatoses, and infections, and any or all of them may be bothersome to the busy doctor. Using an implant or hearing aid is one of the treatment strategies for deafness. However, these medical devices are not useful for every eligible patient. With the right therapy, many of these issues are not life-threatening and can be treated with confidence in a positive outcome. As medical research and treatment have advanced dramatically in the past ten years, tissue engineering (TE) has emerged as a promising method to regenerate damaged tissue, raising the prospect of a permanent cure for deafness. Decellularization is now seen as a promising development for regenerative medicine, and an increasing number of applications are being found for acellular matrices. Studies on decellularization show that natural scaffolds made from decellularized tissues can serve as a suitable platform while preserving the main components, and the preparation of such scaffolds will be an important part of future bioscience research. It can have wide applications in regenerative medicine and TE. This review intends to give an overview of the status of research and alternative scaffolds in inner and outer ear regenerative medicine from both a preclinical and clinical perspective for ear disorders in order to show how ongoing TE research has the potential to advance and enhance novel disease treatments.

Enhancing Osteogenesis through Bio-Inspired Recombinant Coral Protein Galaxin by Targeting Mitochondrial Metabolism and ATP Production

Bio-inspired coral-derived scaffolds have been adopted for bone regeneration. However, these confront challenges such as the limited osteoinductive properties, environmental concerns, and ambiguous calcification mechanisms in coral proteins. In this study, the role of the recombinant coral protein galaxin in promoting osteogenesis is investigated. The observations reveal that recombinant galaxin regulates the mitochondrial metabolism in mouse pre-osteoblasts by interacting with the β subunit of ATP synthase. This ultimately promotes osteogenesis of pre-osteoblasts. Furthermore, galaxin is integrated with gelatin methacryloyl (GelMA) and assess the osteogenic potential of the resulting galaxin-GelMA composites in mouse mandibular defects. The observations emphasize the distinctive role of galaxin in regulating mitochondrial functionality and osteogenesis. Additionally, these provide prospective insights for further applications of bio-inspired recombinant coral proteins in regenerative medicine.

Composite cryogel of gelatin/nanofibrillated cellulose/partially demineralized chitin with potential for bone tissue engineering

Fabrication of macroporous scaffolds with favorable mechanical and biological properties based on natural polysaccharides embedding inorganic components has emerged as a promising alternative for bone regeneration. We hypothesized that partially demineralized chitin containing natural calcium phosphate with suitable mechanical strength as the inorganic component is more favorable for this purpose than commonly used nano-hydroxyapatite (nHA). Therefore, a macroporous cryogel scaffold composed of gelatin (G), nanofibrillated cellulose (NFC), and partially demineralized chitin (PDCh), chemically crosslinked with oxidized dextran (ODex), was developed in this study. The scaffold exhibited suitable aqueous solvent absorption, with a controlled degradation and proper calcium phosphate concentration and a 50-500 μm pore size distribution that promoted cell growth and osteogenesis. Incorporating PDCh provided a high surface-to-volume ratio and significantly enhanced the scaffold's mechanical properties with a compressive strength of 315.4 kPa, suitable for cancellous bone regeneration. Moreover, the presence of natural calcium phosphate in PDCh led to superior biocompatibility and bone differentiation in human mesenchymal stem cells (hMSCs), as evidenced by an increase in calcium deposition, higher alkaline phosphatase (ALP) activity, and an increase in collagen-type 1 and osteocalcin gene expression compared to scaffold containing nHA. These results demonstrated the promising potential of gelatin/nanofibrillated cellulose/PDCh cryogel scaffolds for bone tissue engineering applications.

Emerging nanomedicines for macrophage-mediated cancer therapy

Tumor-associated macrophages (TAMs) contribute to tumor progression by promoting angiogenesis, remodeling the tumor extracellular matrix, inducing tumor invasion and metastasis, as well as immune evasion. Due to the high plasticity of TAMs, they can polarize into different phenotypes with distinct functions, which are primarily categorized as the pro-inflammatory, anti-tumor M1 type, and the anti-inflammatory, pro-tumor M2 type. Notably, anti-tumor macrophages not only directly phagocytize tumor cells, but also present tumor-specific antigens and activate adaptive immunity. Therefore, targeted regulation of TAMs to unleash their potential anti-tumor capabilities is crucial for improving the efficacy of cancer immunotherapy. Nanomedicine serves as a promising vehicle and can inherently interact with TAMs, hence, emerging as a new paradigm in cancer immunotherapy. Due to their controllable structures and properties, nanomedicines offer a plethora of advantages over conventional drugs, thus enhancing the balance between efficacy and toxicity. In this review, we provide an overview of the hallmarks of TAMs and discuss nanomedicines for targeting TAMs with a focus on inhibiting recruitment, depleting and reprogramming TAMs, enhancing phagocytosis, engineering macrophages, as well as targeting TAMs for tumor imaging. We also discuss the challenges and clinical potentials of nanomedicines for targeting TAMs, aiming to advance the exploitation of nanomedicine for cancer immunotherapy.

Atraumatic Scaphoid Avascular Necrosis After Repeated Steroid Injections

Atraumatic avascular necrosis of the scaphoid is an extremely rare pathology. We present a case of avascular necrosis of the scaphoid following repeat local glucocorticoid injections. A 70-year-old, right-handed woman presented to our clinic with 2 years of atraumatic, progressively worsening left wrist pain and loss of range of motion. Imaging demonstrated fragmentation and avascular necrosis of the scaphoid. The patient underwent uncomplicated scaphoid excision, pisiform excision, and intercarpal arthrodesis, with a good functional outcome. This case highlights both the risk of repeated intra-articular steroid injections and the importance of obtaining serial radiographs when providing intra-articular steroid injections. [Orthopedics. 2025;48(3):188-191.].

Lipocalin-2 Regulates Osteocyte Ferroptosis and Osteocyte-Osteoblast Crosstalk via Wnt Signaling to Control Bone Formation

Osteoporosis is a multifactorial disease, and emerging evidence suggests that iron overload contributes to its progression. Here, we identify Lipocalin-2 (LCN2), a cytokine secreted by bone cells with endocrine effects on other tissues, as a local regulator of osteocyte iron metabolism and a mediator of skeletal deterioration. Our findings reveal that LCN2 promotes iron accumulation, mitochondrial dysfunction, and ferroptosis in osteocytes in a process dependent on LCN2 receptor SLC22A17. Genetic ablation of Lcn2 (Dmp1-Cre; Lcn2 fl/fl ) in osteocytes mitigates their ferroptotic vulnerability by preserving mitochondrial integrity and limiting iron overload. Remarkably, LCN2 deletion enhances osteocyte dendricity and lacunocanalicular network, supporting their function in bone remodeling. Mechanistically, we demonstrate that Lcn2 ablation in osteocytes decreases DKK1 and SOST expression in bone, leading to increased Wnt/β-catenin signaling and osteoblast-driven bone formation. Using in vitro and in vivo approaches, we establish the LCN2-SLC22A17 axis as a key pathway linking iron homeostasis, osteocyte dysfunction, and skeletal remodeling. These findings provide insight into a previously unrecognized mechanism underlying iron-driven bone loss and suggest that targeting LCN2 could offer therapeutic potential for osteoporosis.

Engeletin Targets Mitochondrial Dysfunction to Attenuate Oxidative Stress and Experimental Colitis in Intestinal Epithelial Cells Through AMPK/SIRT1/PGC-1α Signaling

Inflammatory bowel disease (IBD), encompassing Crohn's disease and ulcerative colitis, is characterized by chronic intestinal inflammation and epithelial barrier disruption. Emerging evidence highlights mitochondrial dysfunction as a pivotal contributor to IBD pathogenesis, where impaired mitochondrial homeostasis in intestinal epithelial cells (IECs) disrupts redox balance, exacerbates oxidative stress, and triggers apoptosis, further compromising barrier integrity. This study investigated the therapeutic effects of Engeletin (Eng), a dihydroflavonoid from Smilax glabra Roxb., in dextran sulfate sodium (DSS)-induced colitis mice and colonic organoid models. Eng administration (10, 20, 40 mg/kg) significantly alleviated colitis symptoms, including weight loss, disease activity index (DAI) scores, and colon shortening, while restoring intestinal barrier integrity through the upregulation of tight junction proteins (ZO-1, claudin-1) and goblet cell preservation. Eng suppressed NF-κB-mediated inflammation and activated the Nrf2 antioxidant pathway, as well as reduced oxidative stress markers (MDA, CAT, GSH, and SOD). It attenuated epithelial apoptosis by balancing pro- and anti-apoptotic proteins (Bax/Bcl2, c-caspase3) and ameliorated mitochondrial dysfunction via enhanced ATP production, mtDNA levels, and complex I/IV activity. Mechanistically, Eng activated the AMPK/SIRT1/PGC-1α axis, and pharmacological inhibition of PGC-1α abolished its mitochondrial protective and anti-apoptotic effects. These findings demonstrate that Eng alleviates colitis by targeting mitochondrial homeostasis and oxidative stress through AMPK/SIRT1/PGC-1α signaling, offering a multitargeted strategy for IBD therapy.

Nanomaterial-Based Drug Delivery Systems Targeting Functional Cells for Osteoarthritis Treatment: Mechanisms, Challenges and Future Prospects

Osteoarthritis (OA) represents a chronic joint disease characterized by articular cartilage degeneration, synovial inflammation, and subchondral bone erosions. Functional cells in OA mainly include macrophages, synoviocytes, chondrocytes, and mesenchymal stem cells. These cells can secrete cytokines and non-coding RNAs and exosomes and interact with each other to coregulate the progression of OA. Some nanomaterial-based drug delivery systems (DDSs) surface ligands can alleviate OA by targeting receptors on the surface of functional cells. Meanwhile, other nanomaterial-based DDSs, whose surfaces are masked by the cell membranes or extracellular vesicles of these functional cells, treat OA by targeting and attacking the diseased site. When ligand-modified nanomaterials target specific functional cells to treat OA, the functional cells are attacked. Functional cells become attackers, similar to arrows, when their cell membranes or extracellular vesicles are modified into nanomaterials to deliver drugs for OA treatment. An increasing number of studies have been conducted on nanomaterial-based DDS-targeted functional cells for the treatment of OA, but none has summarized the corresponding research progress and mechanism of action. In this review, the related references on the treatment of osteoarthritis with nanomaterial-based DDSs targeting functional cells have been included, and how a variety of functional cells can be engineered into nanomaterial-based DDSs serving as targets or arrows to treat OA has been summarised for the first time, providing a new idea and method for the targeted treatment of OA.

An Injectable Kartogenin-Incorporated Hydrogel Supports Mesenchymal Stem Cells for Cartilage Tissue Engineering

BACKGROUND

Cartilage defects and injuries often lead to osteoarthritis, posing significant challenges for cartilage repair. Traditional treatments have limited efficacy, necessitating innovative therapeutic strategies. This study aimed to develop an injectable hydrogel-based tissue engineering construct to enhance cartilage regeneration by combining mesenchymal stem cells (MSCs) and the small molecule drug kartogenin (KGN).

METHODS

An injectable hydrogel was synthesized by crosslinking carboxymethyl chitosan (CMC) with aldehyde-modified cellulose nanocrystals (DACNCs). KGN was incorporated into the hydrogel during crosslinking to achieve sustained drug release. Three hydrogels with varying CMC/DACNC molar ratios (MR = 0.11, 0.22, and 0.33) were developed and characterized for their structural, mechanical, and biocompatible properties. The hydrogel with the optimal ratio (MR = 0.33) was further evaluated for its ability to support MSC viability and differentiation in vitro. Additionally, signaling pathways (TGF-β, FOXO, and PI3K-AKT) were investigated to elucidate the underlying mechanisms. In vivo efficacy was assessed using a rabbit femoral trochlear cartilage defect model.

RESULTS

The hydrogel with a higher CMC/DACNC molar ratio (MR = 0.33) exhibited increased compressive modulus, a reduced swelling rate, and superior biocompatibility, effectively promoting MSC differentiation in vitro. Signaling pathway analysis revealed activation of the TGF-β, FOXO, and PI3K-AKT pathways, suggesting enhanced chondrogenic potential. In vivo experiments demonstrated that the KGN-MSC-encapsulated hydrogel significantly improved cartilage repair.

CONCLUSIONS

The injectable CMC/DACNC hydrogel, combined with KGN and MSCs, synergistically enhanced cartilage regeneration both in vitro and in vivo. This study highlights the potential of this hydrogel as a promising scaffold for cartilage tissue engineering, offering a novel therapeutic approach for cartilage defects and injuries.

Bioinspired Lipid Nanoparticles with Prolonged Cartilage Retention Boost Regeneration in Early Osteoarthritis and Large Cartilage Defects

Osteoarthritis (OA) leads to the progressive degeneration of articular cartilage, yet there is currently no effective treatment available for both the early and late stages of osteoarthritis. Cartilage regeneration requires the action and prolonged retention of multiple drugs at injured sites to recruit endogenous cells and facilitate cartilage formation. Here, we propose a cartilage-binding-peptide-modified lipid nanoparticle as a drug carrier to achieve sustained release of protein (TGF-β3) and small molecular drugs (KGN) for one month. Through systematic screening of multiple peptides targeting collagen II or chondrocytes, we identify a decorin-derived-peptide-modified lipid nanoparticle with precise targeting and prolonged retention capability in cartilage. Improved nanoparticle stability, high drug loading, and sustainable dual-drug release are achieved through interbilayer cross-linking of adjacent lipid bilayers within multilamellar vesicles. In a surgical model of rat OA, the nanoparticle loading with TGF-β3 and KGN protects injured cartilage from degeneration progression. For severe cartilage injury (full-thickness defects) in a rabbit model, the nanoparticle facilitates the regeneration of high-quality hyaline-like cartilage, which is a rare achievement in full-thickness cartilage regeneration through nanoparticle-based drug delivery. This work presents a strategy for the rational design of bioinspired cartilage-binding peptide-modified lipid-based drug carriers to promote hyaline-like cartilage regeneration.

Evaluation of proanthocyanidins in treating Type 2 diabetic osteoporosis via SIRT6/Nrf2/GPX4 pathways

This study investigates the therapeutic potential of proanthocyanidins (PAC) in addressing Type 2 diabetic osteoporosis (T2DOP) by activating the SIRT6/Nrf2/GPX4 signaling pathways. T2DOP is characterized by compromised bone structure and heightened oxidative stress, where ferroptosis plays a pivotal role. Utilizing a T2DOP mouse model and MC3T3-E1 cells under high glucose conditions, we evaluated the impact of PAC on bone health and iron homeostasis. Our results, obtained through micro-CT, histological staining, Western blot, and immunofluorescence analyses, revealed reductions in bone density and decreased GPX4 expression in T2DOP conditions, indicating ferroptosis and oxidative stress. However, PAC treatment improved trabecular bone structure, reduced bone marrow adipocytes, decreased oxidative stress, and enhanced expression of key osteogenic proteins. These findings highlight PAC's potential in mitigating T2DOP through the SIRT6/Nrf2/GPX4 pathways, offering promising therapeutic insights for managing diabetic osteoporosis.

The bone microenvironment: new insights into the role of stem cells and cell communication in bone regeneration

Mesenchymal stem cells (MSCs) play a crucial role in bone formation and remodeling. Intrinsic genetic factors and extrinsic environmental cues regulate their differentiation into osteoblasts. Within the bone microenvironment, a complex network of biochemical and biomechanical signals orchestrates bone homeostasis and regeneration. In addition, the crosstalk among MSCs, immune cells, and neighboring cells-mediated by extracellular vesicles and non-coding RNAs (such as circular RNAs and micro RNAs) -profoundly influences osteogenic differentiation and bone remodeling. Recent studies have explored specific signaling pathways that contribute to effective bone regeneration, highlighting the potential of manipulating the bone microenvironment to enhance MSC functionality. The integration of advanced biomaterials, gene editing techniques, and controlled delivery systems is paving the way for more targeted and efficient regenerative therapies. Furthermore, artificial intelligence could improve bone tissue engineering, optimize biomaterial design, and enable personalized treatment strategies. This review explores the latest advancements in bone regeneration, emphasizing the intricate interplay among stem cells, immune cells, and signaling molecules. By providing a comprehensive overview of these mechanisms and their clinical implications, we aim to shed light on future research directions in this rapidly evolving field.

Circular RNA circSTX12 regulates osteo-adipogenic balance and proliferation of BMSCs in senile osteoporosis

Increased adipogenic differentiation and decreased osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) along with slow self-renewal are pivotal causes for decreased bone formation in senile osteoporosis. Circular RNAs (circRNAs) play important roles in cell proliferation and differentiation, and are closely related to osteoporosis. Whether circRNAs orchestrate the adipo-osteogenic balance and the proliferation of BMSCs in osteoporosis remains unclear. We found in this study that circSTX12 was abnormally upregulated in bone sections from osteoporosis patients and in BMSCs from aged mice, as well as in later-generation human BMSCs in culture. Knockdown of circSTX12 in BMSCs resulted in enhanced osteogenesis, decreased adipogenesis, and increased proliferation capacity; circSTX12 overexpression had the opposite effect. RNA pull-down and mass spectrometry revealed the interactions between circSTX12 with CBL and LMO7. At the molecular level, circSTX12 regulated cell fate in BMSCs by competitively binding to CBL, reducing the ubiquitination-mediated degradation of MST1 and thereby activating the Hippo pathway, a key regulator of adipo-osteogenic balance. Knockdown of circSTX12 promoted the nuclear localization of YAP. In addition, our findings suggest that LMO7 mediates circSTX12-induced BMSCs proliferation by regulating the transcription of CCNA2, CCNH, and CCND1. In vivo, injection of antisense oligonucleotides (ASOs) to knockdown circSTX12 promoted bone formation in aged mice. Our results provide evidence for circSTX12 as a regulator of adipo-osteogenic differentiation and proliferation of BMSCs through binding to CBL and LMO7, respectively. Targeting circSTX12 may be a novel approach for osteoporosis treatment.

The Role of Ferroptosis in Osteoporosis and Advances in Chinese Herbal Interventions

OP, a systemic bone disorder marked by reduced bone mass and heightened fracture risk, poses a significant global health burden, particularly among aging populations. Current treatments, including bisphosphonates and calcium supplementation, are limited by adverse effects and incomplete efficacy. Emerging research highlights ferroptosis-an iron-dependent cell death driven by lipid peroxidation-as a critical contributor to OP pathogenesis, characterized by dysregulated iron metabolism, oxidative stress, and lipid peroxide accumulation, which disrupt bone remodeling by impairing osteoblast function and enhancing osteoclast activity. This review elucidates the mechanistic interplay between ferroptosis and OP subtypes (diabetic osteoporosis (DOP), glucocorticoid-induced (GIOP), and postmenopausal osteoporosis (PMOP)) and evaluates the efficacy of Chinese herbal interventions in mitigating ferroptosis-driven bone loss. Key findings reveal that excess iron exacerbates lipid peroxidation via the Fenton reaction, while glutathione peroxidase 4 (GPX4) inactivation and system Xc- inhibition amplify oxidative damage. In DIOP, hyperglycemia-induced ROS and advanced glycation end products suppress osteogenesis, countered by melatonin and naringenin via nuclear factor -related factor 2 (Nrf2)/GPX4 activation. GIOP involves dexamethasone-mediated GPX4 downregulation, mitigated by exosomes and melatonin through phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling. PMOP driven by estrogen deficiency-induced iron overload is alleviated by aconitine and icariin (ICA) via nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and signal transducer and activator of transcription 3 (STAT3) pathways. Chinese herbs, including active compounds (quercetin, gastrodin, ICA, etc.) and formulations (Bugu Shengsui Capsule, Erxian Decoction (EXD), etc.), regulate iron metabolism, enhance antioxidant defenses (Nrf2/heme oxygenase 1(HO-1)), and inhibit lipid peroxidation, effectively restoring bone homeostasis. These findings underscore ferroptosis as a pivotal mechanism in OP progression and highlight the therapeutic promise of Chinese herbs in bridging traditional medicine with modern mechanistic insights. Future research should prioritize elucidating precise molecular targets, optimizing formulations, and validating clinical efficacy to address current therapeutic gaps.

An "EVs-in-ECM" mimicking system orchestrates transcription and translation of RUNX1 for in-situ cartilage regeneration

The self-repair ability of articular cartilage is limited, which is one of the most difficult diseases to treat clinically. Kartogenin (KGN) induces chondrogenesis by regulating RUNX1 mRNA translation and the small molecule compound TD-198946 (TD) promotes chondrogenic differentiation of mesenchymal stem cells (MSCs) through increasing the transcription of RUNX1 mRNA. GelMA hydrogel and liposomes are respectively similar to the extracellular matrix (ECM) and extracellular vesicles (EVs). So, we developed an "EVs-in-ECM" mimicking system by incorporating GelMA and KGN/TD-loaded liposomes to investigate the repair effects of cartilage defect. First, western-blot, RNA fluorescence in situ hybridization (FISH), cellular immuno-fluorescence, co-immuno-precipitation (CO-IP), and qRT-PCR techniques showed that KGN regulated RUNX1 mRNA expression, and then promote chondrogenic differentiation of MSCs. Second, the role of RUNX1 was amplified by orchestrating RUNX1 transcription and translation through TD-198946 (TD) and KGN respectively, and the synergistic effects of TD and KGN on chondrogenesis of MSCs in vitro were discovered. Finally, an "EVs-in-ECM" mimicking system was designed for in situ cartilage repair. When GelMA loaded with KGN and TD liposomes, the hydrogel (KGN + TD@ GelMA) showed biological functions by the continuously controlled release of KGN and TD while maintaining its porous structure and mechanical strength, which enhanced the chondrogenesis of MSCs in one system. The repair performance of "EVs-in-ECM" in vivo was assessed using the articular osteochondral defect model of rat. The implantation of KGN + TD@ GelMA hydrogels effectively exerted favorable osteochondral repair effects showing structures similar to the native tissue, and prevented chondrocyte hypertrophy. The study indicate that the "EVs-in-ECM" mimicking system can act as a highly efficient and potent scaffold for osteochondral defect regeneration.

Key role of the CSE/transsulfuration pathway in macrophage phenotypic change under iron overload

BACKGROUND

Iron homeostasis has a significant impact on the phenotypic transformation of macrophages and is implicated in various diseases. In this study, we evaluated the effect of cystathionine-gamma-lyase (CSE)/transsulfuration pathway in iron-overload induced macrophage phenotype change.

METHODS

The biochemical parameters, such as qRT-PCR, western blot, fluorescence staining, were assessed both in vitro and in vivo.

RESULTS

Iron overload disrupts iron metabolism and alters the expression of genes involved in iron transport, resulting in the polarization of macrophages towards the M1 phenotype and an alternating activation state of M2. Meanwhile, excessive iron led to an increase in lipid peroxidation levels and disrupted cysteine metabolism. By utilizing erastin to inhibit SLC7A11 activity and block exogenous cysteine uptake, we were able to observe the exacerbation of the proinflammatory state in macrophages under conditions of cysteine deprivation. The CSE/transsulfuration pathway, serves as the primary route for endogenous cysteine synthesis. In the presence of iron overload, the expression of CSE was upregulated and further enhanced by cysteine deprivation. Deletion of CSE in CSE-knockout mice exacerbated the inflammatory transition of iron-overloaded macrophages by impacting cysteine metabolism and ferritinophagy.

CONCLUSION

The CSE/transsulfuration pathway regulated macrophage phenotype change under iron-overload, which may offer novel insights into potential therapeutic strategies for iron overload-related disorders.

Application of 4D-Printed Magnetoresponsive FOGS Hydrogel Scaffolds in Auricular Cartilage Regeneration

3D-printed hydrogel scaffolds are widely utilized in auricular cartilage tissue engineering. However, issues such as graft-related inflammation, poor mechanical properties, and the lack of external modulation of 3D-printed scaffolds in vivo have raised significant concerns. To address these challenges, a "fried egg" structure is designed, consisting of chitosan-coated ferroferric oxide magnetic nanoparticles (Fe3O4@CS MNPs), which are uniformly incorporated into hydrogel. Through 4D printing technology, magnetoresponsive hydrogel scaffolds are constructed to overcome the aforementioned limitations. The results demonstrated that, compared to 3D printing, 4D-printed magnetic hydrogel scaffolds significantly enhanced cartilage tissue regeneration in both in vitro and in vivo environments when subjected to an external magnetic field (MF). Furthermore, the mechanical strength of regenerated cartilage approached to that of natural cartilage. The chitosan coating on the surface of MNPs exhibited anti-inflammatory and antibacterial properties, promoting M2 polarization of macrophages and suppressing graft-related inflammation and bacteria. Transcriptomic analysis confirmed that MNPs modulate macrophage immunity by activating JAK2/STAT3 signaling pathway. Taken together, a magnetoresponsive multifunctional scaffold is designed that can be externally controlled by magnetic fields to promote ear cartilage tissue regeneration. The regenerated cartilage exhibits excellent biocompatibility, anti-inflammatory, antibacterial properties, and mechanical performance, providing new insights for auricular cartilage tissue engineering.

Crocin facilitates osteogenesis and angiogenesis by moderating oxidative stress and ferroptosis via Nrf2/GPX4 pathway

Bone formation is a complex multi-factor process of bone defect healing. Oxidative stress (OS) is predisposed to induce regulatory cell death (RCD), such as ferroptosis. At present, the antioxidant effects of Crocin on erastin induced oxidative damage were studied. The activity of bone marrow mesenchymal stem cells (BMSCs) and human umbilical vein endothelial cells (HUVECs) was detected by CCK-8 and EdU staining. The production of reactive oxygen species (ROS), MDA, SOD and GSH were evaluated. Western blotting assay was used to detect ferroptosis-related proteins. The osteogenic function of BMSCs was determined by alkaline phosphatase (ALP) activity, ALP staining and alizarin red S (ARS) staining. Western blotting and RT-PCR assays were used to detect the expression of osteogenic proteins and genes. Angiogenesis of HUVECs was evaluated by tube formation, RT-PCR, scratch test and Transwell assay. The results showed that Crocin can promote the osteogenic function of BMSCs and angiogenesis of HUVECs. In addition, Crocin protects cells from erastin-induced oxidative injury and inhibits ferroptosis via the Nrf2/GPX4 pathway. These findings suggest that Crocin can promote bone defect healing by regulating OS and inhibiting ferroptosis through the Nrf2/GPX4 pathway.

Differential risk of autoimmune disorders in non-traumatic osteonecrosis: clue to pathogenesis

INTRODUCTION

Non-traumatic osteonecrosis is a frequent complication in patients with autoimmune disorders, though its prevalence varies markedly depending upon the type of disorder. Understanding the causes of this difference can help uncover the underlying pathophysiology of osteonecrosis and guide the development of effective preventive and therapeutic strategies.

AREAS COVERED

In this perspective study, we reviewed available databases, including PubMed, Cochrane Library, Scopus, and Web of Science, to explore why the risk of osteonecrosis varies among different autoimmune disorders. Is this variation primarily due to the disease's pathophysiology, the use of medications such as corticosteroids, or a combination of both? If both factors are involved, what is the extent of each contribution in this context?

EXPERT OPINION

Non-traumatic osteonecrosis is often induced by an interaction between disease pathophysiology and corticosteroid use. In patients with different autoimmune disorders but an identical history of corticosteroid use, the risk of osteonecrosis is influenced by how the underlying pathophysiology compromises bone health. In autoimmune disorders with multiple adverse effects on bone, such as SLE (systemic lupus erythematosus), there is a much higher risk of osteonecrosis compared to disorders with minimal impact on bone health, such as celiac disease and MS (multiple sclerosis).

Versatile application of magnesium-related bone implants in the treatment of bone defects

Magnesium-related bone implants have garnered significant attention in the treatment of bone defects. The applications of magnesium in promoting bone repair mainly include degradable magnesium-based scaffolds owing to its special physical properties and composite materials modified by magnesium ions because of its biological activity. Although numerous studies have confirmed the unique application advantages and efficacy of magnesium in promoting bone repair, some obvious shortcomings persist, including the rapid degradation of magnesium-based scaffolds. In this review, the deficiencies of magnesium and its alloys in the construction of orthopedic implants and their key influencing factors were summarized; furthermore, some advanced improvement schemes were summarized and analyzed. Additionally, the application strategies of magnesium-modified bone implants are summarized and discussed. Lastly, this review incorporates the latest research and discoveries on magnesium in orthopedic science, comprehensively exploring the mechanism of magnesium's role in the complex microenvironment of bone defects from multiple dimensions. This paper provides a comprehensive summary and analysis of cutting-edge concepts in the design and development of magnesium-based bone implants, considering various perspectives such as the physical properties and biological functions of magnesium.

Hydrogels as drug delivery platforms for orthopedic diseases treatment: A review

The skeletal system serves as a crucial support structure for the human body, any damage or disease to bones can result in prolonged pain, impaired mobility, and other negative outcomes. For the treatment of bone diseases, with the in-depth study of the therapeutic mechanism, various small molecule drugs, cells, cytokines, growth factors, bioactive ions, collectively referred to as "drugs" in this context, are increasingly investigated for their potential application in surgical procedures, defect repair, or treatment of diseased bone regions. However, various challenges, including, low stability, the necessity for precise dosage control, are encountered in the administration of drugs. Consequently, the advancement of drug delivery platforms is crucial to safeguard drug efficacy and address the requirement for dosage regulation. Given the attributes of current drug delivery platforms, hydrogels exhibit favorable biocompatibility and offer the ability to easily regulate drug loading and release. As a carrier with diverse properties, abundant varieties, optimal performance, hydrogels present a promising solution in drug delivery. This paper aims to analyze the potential of hydrogel as a delivery platform for treating orthopedics diseases by reviewing the characteristics of hydrogel delivery systems, mechanisms of drug binding, current research findings, and projecting future developments in this field.

The status and hotspot analysis of research on extracellular vesicles and osteoarthritis: a bibliometric analysis

Background

Degenerative joint disease, known as osteoarthritis (OA), is characterized by pain, swelling, and decreased mobility. The illness has a major negative influence on patients' quality of life and is common around the world, especially among older people. Nevertheless, there are insufficient possibilities for early diagnosis and therapy. Extracellular vesicles, or EVs, control the immune response, tissue healing, and cellular communication.

Methods

This work offers a bibliometric representation of the areas of focus and correlations between extracellular vesicles and osteoarthritis. We searched for osteoarthritis and extracellular vesicles in publications in the Web of Science Core Collection (WoSCC) database. Bibliometrics, an R package, CiteSpace 6.1. R2, and VOSviewer 1.6.17 were used to perform bibliometric analyses of concentration fields, trends, and relevant factors.

Results

944 papers from 59 nations were published; the countries that contributed the most to the field were China, the USA, and Italy. Professors Laura and Enrico are the top contributors. Sichuan University, Istituto Ortopedico Galeazzi, and Shanghai Jiao Tong University are the top three universities. The International Journal of Molecular Sciences is an excellent publication. Exosome, expression, knee osteoarthritis, extracellular vesicle, mesenchymal stem cell, osteoarthritis, and inflammation are the most often occurring keywords.

Conclusion

These results suggest areas of interest and focus for future research on EVs and OA. This trend suggests that the volume of literature on OA and EVs will continue to rise, with more research being published in the future. This study helps scholars understand current research hotspots in the field and may inspire future research.

The mutual impacts of stem cells and sleep: opportunities for improved stem cell therapy

Sleep is an indispensable physiological function regulated by circadian rhythms, which influence the biological pathways and overall health of the body. Sleep is crucial for the maintenance and restoration of bodily systems, and disturbances can lead to various sleep disorders, which can impair both mental and physical health. Treatment options for these disorders encompass lifestyle modifications, psychotherapy, medications, and therapies such as light therapy and surgery. Not only sleep deprivation has a significant impact on essential organs, but it also influences various types of stem cells in the body. In this review, we explore the connection between sleep and various types of stem cells, highlighting how circadian rhythms regulate stem cell activities that are vital for tissue regeneration and homeostasis. Disruptions in sleep can hinder stem cell self-renewal, homing, proliferation, function, and differentiation, thereby affecting tissue regeneration and overall health. We also discuss how transplantation of stem cells and their products may help improve sleep disorders, how sleep quality affects stem cell behavior, and the implications for stem cell therapies. Notably, while certain stem cell transplantations can disrupt sleep, enhancing sleep quality may improve the efficacy of these therapies. Finally, stem cells can be utilized to model sleep disorders, offering valuable insights into their underlying mechanisms.

Targeting the central and peripheral nervous system to regulate bone homeostasis: mechanisms and potential therapies

The skeleton is innervated by different types of nerves and receives signaling from the nervous system to maintain homeostasis and facilitate regeneration or repair. Although the role of peripheral nerves and signals in regulating bone homeostasis has been extensively investigated, the intimate relationship between the central nervous system and bone remains less understood, yet it has emerged as a hot topic in the bone field. In this review, we discussed clinical observations and animal studies that elucidate the connection between the nervous system and bone metabolism, either intact or after injury. First, we explored mechanistic studies linking specific brain nuclei with bone homeostasis, including the ventromedial hypothalamus, arcuate nucleus, paraventricular hypothalamic nucleus, amygdala, and locus coeruleus. We then focused on the characteristics of bone innervation and nerve subtypes, such as sensory, sympathetic, and parasympathetic nerves. Moreover, we summarized the molecular features and regulatory functions of these nerves. Finally, we included available translational approaches that utilize nerve function to improve bone homeostasis and promote bone regeneration. Therefore, considering the nervous system within the context of neuromusculoskeletal interactions can deepen our understanding of skeletal homeostasis and repair process, ultimately benefiting future clinical translation.

Modified Standard Total en bloc Spondylectomy for Solitary Thoracic or Lumbar Spinal Metastasis: A 1-Stage Posterior Approach Under Direct Visualization

BACKGROUND

Solitary spinal metastasis (SM) is one of the indications for total en bloc spondylectomy (TES). Conventional TES carries the risk of damage to the great vessels anterior to the vertebral column, mainly because of a lack of visualization of the anterior structures. In this study, we devised a modified standard TES technique to achieve direct visualization in a 1-stage posterior approach.

METHODS

Included in this study were patients ≥18 years old with solitary thoracic or lumbar SM who underwent the modified standard TES at our institution between January 2017 and October 2022. Patient data were retrospectively sourced from medical records, and patients had a minimum of 3 months of postoperative follow-up.

RESULTS

This study involved 71 East Asian patients (median age, 57 years; 34 males), comprising 38 patients with thoracic SM and 33 with lumbar SM. Lung cancer was the most common tumor histology. Fourteen patients (19.7%) experienced intraoperative complications; pleural rupture was the predominant complication, and there were no cases of injury to the spinal cord or great vessels. The median operative time was 305 minutes (range, 203 to 660 minutes). The median intraoperative blood loss was 1,000 mL (range, 400 to 4,000 mL). The median perioperative blood transfusion was 4 units (range, 0 to 12 units), and the median hospitalization duration was 17 days (range, 14 to 29 days). Additionally, 27 patients (38.0%) had acute (perioperative) complications. Seven patients were lost to follow-up. Significant clinical improvement was achieved 3 months postoperatively. Postoperative early and late complications were observed in 5 patients. Of the 64 patients with completed follow-up, 47 (73.4%) had negative surgical margins, and none received postoperative radiation therapy. Revision surgery for local tumor recurrence was performed in 4.7% of patients. The median follow-up was 31.5 months (range, 3 to 81 months).

CONCLUSIONS

Our modified standard TES was demonstrated to be a safe and effective surgical technique for solitary thoracolumbar SM.

LEVEL OF EVIDENCE

Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Current perspectives on the dynamic culture of mesenchymal stromal/stem cell spheroids

Mesenchymal stromal/stem cells (MSCs) are promising candidates for regenerative medicine owing to their self-renewal properties, multilineage differentiation, immunomodulatory effects, and angiogenic potential. MSC spheroids fabricated by 3D culture have recently shown enhanced therapeutic potential. MSC spheroids create a specialized niche with tight cell-cell and cell-extracellular matrix interactions, optimizing their cellular function by mimicking the in vivo environment. Methods for 3D cultivation of MSCs can be classified into 2 main forms: static suspension culture and dynamic suspension culture. Numerous studies have reported the beneficial influence of these methods on MSCs, which is displayed by increased differentiation, angiogenic, immunomodulatory, and anti-apoptotic effects, and stemness of MSC spheroids. Particularly, recent studies highlighted the benefits of dynamic suspension cultures of the MSC spheroids in terms of faster and more compact spheroid formation and the long-term maintenance of stemness properties. However, only a few studies have compared the behavior of MSC spheroids formed using static and dynamic suspension cultures, considering the significant differences between their culture conditions. This review summarizes the differences between static and dynamic suspension culture methods and discusses the biological outcomes of MSC spheroids reported in the literature. In particular, we highlight the advantages of the dynamic suspension culture of MSC spheroids and contemplate its future applications for various diseases.

Human umbilical cord mesenchymal stem cell-derived exosomes promote osteogenesis in glucocorticoid-induced osteoporosis through PI3K/AKT signaling pathway-mediated ferroptosis inhibition

Glucocorticoid-induced osteoporosis (GIOP), the most common cause of secondary osteoporosis, is characterized by significant bone loss, decreased bone quality, and increased fracture risk. The current treatments for GIOP have several drawbacks. Exosomes are vital for cellular processes. However, very few studies have focused on using human umbilical cord mesenchymal stem cell-derived exosomes (hUCMSC-EXOs) for GIOP treatment. In vitro and in vivo dexamethasone was used to evaluate the therapeutic effects of hUCMSC-EXOs on GIOP. CCK-8 and EdU assays were used to evaluate cell viability and proliferation, respectively. We conducted an alkaline phosphatase activity assay, alizarin red staining, Western blotting, and real-time PCR to detect the effect on osteogenesis. TMT-labeled quantitative proteomic and bioinformatic analyses were performed. Furthermore, we performed Western blotting, immunofluorescence, reactive oxygen species assays, and lipid peroxidation assays to investigate the regulatory mechanism by which hUCMSC-EXOs affect cell proliferation and osteogenic differentiation. The in vivo effects of hUCMSC-EXOs were evaluated using micro-CT, hematoxylin, and eosin staining, and immunohistochemical staining. We found that hUCMSC-EXOs reversed the inhibitory effects of glucocorticoids on human bone marrow stromal cell (hBMSC) proliferation and osteogenic differentiation and demonstrated that hUCMSC-EXOs reversed GIOP via the PI3K/AKT signaling pathway, inhibiting lipid peroxidation in vitro and in vivo. HUCMSC-EXOs promote hBMSC osteogenesis through the PI3K/AKT signaling pathway, inhibit ferroptosis, and have therapeutic potential for GIOP in mice.

Simvastatin modulates osteogenic differentiation in Stem Cells isolated from Apical Papilla

BACKGROUND

Simvastatin modulates numerous stem cell functions, including stemness maintenance and differentiation. The present study aimed to explore the effect of simvastatin on the osteogenic differentiation of Stem Cells isolated from Apical Papilla (SCAPs) in vitro.

METHODS

Cells were isolated from apical papilla, and mesenchymal stem cell features were characterised. Cells were treated with various concentrations of simvastatin (100-1,000 nM). The mRNA expression profile of simvastatin-treated SCAPs was examined using RNA sequencing technique. The osteogenic differentiation abilities were assessed. Alkaline phosphatase activity was determined. The mineralisation was visualised using Alizarin Red S and Von Kossa staining. The osteogenic marker gene expression was determined using a quantitative polymerase chain reaction.

RESULTS

RNA sequencing data demonstrated that simvastatin upregulated genes enriched in those pathways involving osteogenic differentiation, including the TGF-β signalling pathway, FoxO signalling pathway, and MAPK signalling pathway, while the downregulated genes were involved in pathways related to cell proliferation and apoptosis, for example, DNA replication, cell cycle, and p53 signalling pathway. Simvastatin promoted mineral deposition in a dose-dependent manner, corresponding with the upregulation of osteogenic marker genes namely OSX, DMP1, DSPP, and OCN. Pretreatment with TGF-β receptor inhibitor, SB431542, resulted in a moderately attenuated effect on simvastatin-induced mineralisation and osteogenic marker gene expression.

CONCLUSIONS

Simvastatin enhances osteogenic differentiation in SCAPs, potentially via TGF-β signalling, implicating its potential role as an adjunctive molecule in dental pulp healing and regeneration in vital pulp treatment approaches.

Skeletal muscle atrophy induced by aging and disuse atrophy are strongly associated with the upregulation of the endoplasmic stress protein CHOP in rats

BACKGROUND

While canonical anabolic and proteolytic pathways have been well examined in the context of skeletal muscle proteostasis, the roles of endoplasmic reticulum stress (ERS) and the induced unfolded protein response (UPR) are underappreciated. Thus, we aimed to determine whether aging and/or disuse atrophy in rats altered skeletal muscle ERS/UPR markers.

METHODS AND RESULTS

Soleus (SOL) and plantaris (PLT) muscles of 3-month-old (mo), 6 mo, 12 mo, 18 mo, and 24 mo rats (9-10 per group, 48 in total) were analyzed for UPR proteins with further analysis performed on the protein CHOP. The gastrocnemius muscles of 4 mo rats that had undergone hindlimb immobilization (HLI, n = 12) or sham casting (CTL, n = 12) were analyzed for similar targets as well as more extensive CHOP-related targets. CHOP protein was greater in the PLT and SOL of 18 and 24 mo rats versus other age groups (P < 0.05). Moreover, negative correlations existed between CHOP expression and normalized PLT (R=-0.702, P < 0.001) and SOL (R=-0.658, P < 0.001) muscle weights in all rats analyzed at different ages. CHOP protein expression was also greater in the gastrocnemius of HLI versus CTL rats (P < 0.001), and a negative correlation existed between CHOP protein expression and normalized muscle weights in these rats (R=-0.814, P < 0.001). Nuclear CHOP protein levels (P < 0.010) and genes transcriptionally regulated by CHOP were also greater in HLI versus CTL rats (P < 0.001) implicating transcriptional activity of CHOP is elevated during disuse atrophy.

CONCLUSIONS

CHOP is operative during aging- and disuse-induced skeletal muscle atrophy in rodents, and more research is needed to determine if CHOP is a key mechanistic driver of these processes.

Hepcidin knockout exacerbates hindlimb unloading-induced bone loss in mice through inhibiting osteoblastic differentiation

BACKGROUND

An oligopeptide hepcidin is encoded by the human HAMP gene (Hamp in mice). Its deficiency can result in iron overload, while excess may lead to iron deficiency. Hepcidin knockout mice exhibited iron accumulation in multiple tissues, accompanied by degeneration of bone microarchitecture and reduced biomechanical properties. Astronauts who are exposed to weightlessness during prolonged spaceflight experience bone loss. After space missions, an interrelation exists between iron stores and bone mineral density (BMD). Bone loss in mice due to unloading is linked to iron excess and involves hepcidin. The potential role of hepcidin in unloading-induced bone loss remains unclear.

METHODS

Our study conducted relevant experiments using hepcidin knockout mice and their primary osteoblasts as the research subjects. We used the hindlimb unloading (HLU) model and the random positioning machine (RPM) system to simulate weightlessness in vivo and in vitro.

RESULTS

HLU mice exhibited reduced hepcidin levels in the serum and liver. Hepcidin knockout further diminished BMD and bone mineral content (BMC) in the femurs of HLU mice. Similarly, the bone volume fraction (BV/TV) and connectivity density (Conn.Dn) followed this downward trend, whereas trabecular separation (Tb.Sp) showed an inverse pattern. Moreover, hepcidin knockout decreased the ultimate load and elastic modulus in the tibias of HLU mice. Hepcidin knockout decreased PINP levels in the serum, a commonly used marker for bone formation, alongside elevated iron levels in the serum, liver, and bone of HLU mice. We also found higher serum MDA and SOD levels in these mice. In vitro, experimental data indicated that hepcidin knockout suppresses the osteoblastic differentiation capacity under RPM conditions. Additionally, this condition upregulates SOST protein levels and downregulates LRP6 and β-catenin protein levels in osteoblasts.

CONCLUSION

Hepcidin knockout exacerbates bone loss in HLU mice, most likely due to reduced osteoblastic activity.

From death to birth: how osteocyte death promotes osteoclast formation

Bone remodeling is a dynamic and continuous process involving three components: bone formation mediated by osteoblasts, bone resorption mediated by osteoclasts, and bone formation-resorption balancing regulated by osteocytes. Excessive osteocyte death is found in various bone diseases, such as postmenopausal osteoporosis (PMOP), and osteoclasts are found increased and activated at osteocyte death sites. Currently, apart from apoptosis and necrosis as previously established, more forms of cell death are reported, including necroptosis, ferroptosis and pyroptosis. These forms of cell death play important role in the development of inflammatory diseases and bone diseases. Increasing studies have revealed that various forms of osteocyte death promote osteoclast formation via different mechanism, including actively secreting pro-inflammatory and pro-osteoclastogenic cytokines, such as tumor necrosis factor alpha (TNF-α) and receptor activator of nuclear factor-kappa B ligand (RANKL), or passively releasing pro-inflammatory damage associated molecule patterns (DAMPs), such as high mobility group box 1 (HMGB1). This review summarizes the established and potential mechanisms by which various forms of osteocyte death regulate osteoclast formation, aiming to provide better understanding of bone disease development and therapeutic target.

Distinct role of perlecan in mesenchymal tissue regeneration via genetic and epigenetic modification

Perlecan (HSPG2), a key component of basement membrane proteins, plays a crucial role in tissue development and regeneration. However, its direct impact on mesenchymal tissue differentiation, mediated through both genetic modification (gain- and loss-of-function mutations) and epigenetic changes (matrix microenvironment alterations), remains underexplored. In this study, we utilized CRISPR/Cas9 to achieve knockout (KO) and overexpression (OE) of HSPG2 in human fetal nucleus pulposus stem/progenitor cells (NPSCs) and adult infrapatellar fat pad-derived stem cells (IPFSCs) to investigate perlecan's influence on mesenchymal differentiation. We also assessed the effects of decellularized extracellular matrix (dECM) derived from fetal NPSCs with modified HSPG2 expression on the proliferation and differentiation of adult NPSCs. Our findings demonstrate that HSPG2-KO enhance chondrogenic differentiation, while HSPG2-OE suppressed adipogenic differentiation in both fetal NPSCs and adult IPFSCs. Notably, dECM from HSPG2-OE fetal NPSCs significantly promoted chondrogenic differentiation in adult NPSCs, suggesting potential applications for perlecan in developing advanced biomaterials for cartilage regeneration.