Mesenchymal stem cell-derived exosomes ameliorate intervertebral disc degeneration via anti-oxidant and anti-inflammatory effects

Role of oxidative stress in intervertebral disc degeneration: mechanisms, pathogenesis, and therapeutic strategies

Intervertebral disc degeneration (IDD) is a prevalent and debilitating spinal condition, characterised by the progressive degradation of disc structure and function, often accompanied by pain. Despite our increasing understanding of IDD, the precise mechanisms underlying its development and potential therapeutic targets remain incompletely understood. Recent research has highlighted that oxidative stress, along with immune abnormalities, mechanical loading imbalances, and metabolic disruptions, play a pivotal role in IDD initiation and progression. Oxidative stress in IDD results from an overproduction of reactive oxygen species (ROS) and a compromised ability to eliminate them, disrupting the redox homeostasis within the intervertebral disc. This disturbance in redox balance leads to extracellular matrix degradation (ECM), induces cellular apoptosis, and worsens the damage to disc tissues. This review provides a comprehensive overview of the pathophysiological processes of IDD, with a particular focus on the role of oxidative stress. Additionally, we explore current advancements in therapeutic strategies targeting oxidative stress, including antioxidant drugs, biomaterials, and stem cell-based approaches, offering promising avenues for the management and treatment of IDD.

Pyroptosis: A spoiler of peaceful coexistence between cells in degenerative bone and joint diseases

BACKGROUND

As people age, degenerative bone and joint diseases (DBJDs) become more prevalent. When middle-aged and elderly people are diagnosed with one or more disorders such as osteoporosis (OP), osteoarthritis (OA), and intervertebral disc degeneration (IVDD), it often signals the onset of prolonged pain and reduced functionality. Chronic inflammation has been identified as the underlying cause of various degenerative diseases, including DBJDs. Recently, excessive activation of pyroptosis, a form of programed cell death (PCD) mediated by inflammasomes, has emerged as a primary driver of harmful chronic inflammation. Consequently, pyroptosis has become a potential target for preventing and treating DBJDs.

AIM OF REVIEW

This review explored the physiological and pathological roles of the pyroptosis pathway in bone and joint development and its relation to DBJDs. Meanwhile, it elaborated the molecular mechanisms of pyroptosis within individual cell types in the bone marrow and joints, as well as the interplay among different cell types in the context of DBJDs. Furthermore, this review presented the latest compelling evidence supporting the idea of regulating the pyroptosis pathway for DBJDs treatment, and discussed the potential, limitations, and challenges of various therapeutic strategies involving pyroptosis regulation.

KEY SCIENTIFIC CONCEPTS OF REVIEW

In summary, an interesting identity for the unregulated pyroptosis pathway in the context of DBJDs was proposed in this review, which was undertaken as a spoiler of peaceful coexistence between cells in a degenerative environment. Over the extended course of DBJDs, pyroptosis pathway perpetuated its activity through crosstalk among pyroptosis cascades in different cell types, thus exacerbating the inflammatory environment throughout the entire bone marrow and joint degeneration environment. Correspondingly, pyroptosis regulation therapy emerged as a promising option for clinical treatment of DBJDs.

Exploring extracellular vesicles as novel therapeutic agents for intervertebral disc degeneration: delivery, applications, and mechanisms

Intervertebral disc degeneration is a multifactorial degenerative disease that poses a significant threat to the health of the elderly population. Current treatments primarily focus on physical therapy, medication, and surgery to alleviate symptoms associated with disc compression but do not address the progression of degeneration. Therefore, this review aimed to explore the potential of extracellular vesicle therapy as a novel preventive strategy to delay degeneration and enhance tissue repair in intervertebral discs. We cover the pathogenic mechanisms underlying intervertebral disc degeneration, including inflammation, apoptosis, pyroptosis, ferroptosis, autophagy dysregulation, and the roles of non-coding RNAs. Subsequently, we discussed the therapeutic potential of extracellular vesicles and their molecular components, such as proteins, RNAs, and lipids, in modulating these pathways to counter intervertebral disc degeneration. We provides a comprehensive review of the significant role of extracellular vesicle cargo in mediating repair mechanisms. It discusses the functional enhancement advantages exhibited by extracellular vesicles under current bioengineering modifications and drug loading. The challenges and future prospects of utilizing extracellular vesicle therapy to treat this degenerative condition are also summarized.

MSC-derived exosomes alleviate oxidative stress-induced lysosomal membrane permeabilization damage in degenerated nucleus pulposus cells via promoting m6A demethylation of Nrf2

Lysosomal membrane permeabilization (LMP) is a specific feature of lysosomal dysfunction; however, its specific role and underlying mechanisms involved in intervertebral disc degeneration (IVDD) remain elusive. Although the therapeutic potential of mesenchymal stem cell-derived exosomes (MSC-Exo) in ameliorating IVDD has been verified, it remains unclear whether their protective effects are referred to LMP damage. This work revealed that oxidative stress induced-LMP damage directly mediated the pathological process of human IVDD, which aggravated nucleus pulposus cells (NPCs) senescence by disrupting lysosomal autophagy function. Conversely, umbilical cord derived MSC-Exo inhibited LMP damage in degenerated NPCs by activating Nrf2-medaited anti-oxidative stress effects. Specifically, MSC-Exo facilitated H3K27ac modification in the demethylase FTO promoter by promoting histone acetyltransferase activity of p300/CBP, resulting in the enhanced FTO transcription. This process inhibited the elevation of N6-methyladenosine (m6A) modification of Nrf2 in degenerated NPCs, resulting in less recognition of YTHDF2 and enhanced stability of Nrf2 expression. Here, our finding demonstrates oxidative stress induced-LMP damage potentially establishing pathological conditions conducive to the progression of IVDD, and providing epigenetic regulatory targets for MSC-Exo in the treatment of IVDD.

Stem cell therapy for intervertebral disc degeneration: Clinical progress with exosomes and gene vectors

Intervertebral disc degeneration is a leading cause of lower back pain and is characterized by pathological processes such as nucleus pulposus cell apoptosis, extracellular matrix imbalance, and annulus fibrosus rupture. These pathological changes result in disc height loss and functional decline, potentially leading to disc herniation. This comprehensive review aimed to address the current challenges in intervertebral disc degeneration treatment by evaluating the regenerative potential of stem cell-based therapies, with a particular focus on emerging technologies such as exosomes and gene vector systems. Through mechanisms such as differentiation, paracrine effects, and immunomodulation, stem cells facilitate extracellular matrix repair and reduce nucleus pulposus cell apoptosis. Despite recent advancements, clinical applications are hindered by challenges such as hypoxic disc environments and immune rejection. By analyzing recent preclinical and clinical findings, this review provided insights into optimizing stem cell therapy to overcome these obstacles and highlighted future directions in the field.

REDOX Imbalance and Oxidative Stress in the Intervertebral Disc: The Effect of Mechanical Stress and Cigarette Smoking on ER Stress and Mitochondrial Dysfunction

Low back pain is a widespread condition that significantly impacts quality of life, with intervertebral disc degeneration (IDD) being a major contributing factor. However, the underlying mechanisms of IDD remain poorly understood, necessitating further investigation. Environmental risk factors, such as mechanical stress and cigarette smoke, elevate reactive oxygen species levels from both endogenous and exogenous sources, leading to redox imbalance and oxidative stress. The endoplasmic reticulum (ER) and mitochondria, two key organelles responsible for protein folding and energy production, respectively, are particularly vulnerable to oxidative stress. Under oxidative stress conditions, ER stress and mitochondrial dysfunction occur, resulting in unfolded protein response activation, impaired biosynthetic processes, and disruptions in the tricarboxylic acid cycle and electron transport chain, ultimately compromising energy metabolism. Prolonged and excessive ER stress can further trigger apoptosis through ER-mitochondrial crosstalk. Given the unique microenvironment of the intervertebral disc (IVD)-characterized by hypoxia, glucose starvation, and region-specific cellular heterogeneity-the differential effects of environmental stressors on distinct IVD cell populations require further investigation. This review explores the potential mechanisms through which environmental risk factors alter IVD cell activities, contributing to IDD progression, and discusses future therapeutic strategies aimed at mitigating disc degeneration.

Advancements in Degenerative Disc Disease Treatment: A Regenerative Medicine Approach

Regenerative medicine represents a transformative approach to treating nucleus pulposus degeneration and offers hope for patients suffering from chronic low back pain due to disc degeneration. By focusing on restoring the natural structure and function of the nucleus pulposus rather than merely alleviating symptoms, these innovative therapies hold the potential to significantly improve patient outcomes. As research continues to advance in this field, we may soon witness a paradigm shift in how we approach spinal health and degenerative disc disease. The main purpose of this review is to provide an overview of the various regenerative approaches that target the restoration of the nucleus pulposus, a primary site for initiation of intervertebral disc degeneration.

SOX4 accelerates intervertebral disc degeneration via EZH2/NRF2 pathway in response to mitochondrial ROS-dependent NLRP3 inflammasome activation in nucleus pulposus cells

OBJECTIVE

The transcription factor SRY-related HMG-box 4 (SOX4) has been implicated in intervertebral disc diseases. This study aimed to investigate the role of SOX4 in intervertebral disc degeneration (IDD) and explore the underlying molecular mechanisms.

METHODS

We established an IDD rat model via surgery and analyzed SOX4 expression using qRT-PCR and Western blotting. Histological evaluation, immunohistochemistry, and Safranin O staining assessed IDD progression. In vitro, an IDD cellular model was constructed using IL-1β-stimulated nucleus pulposus (NP) cells. SOX4 knockdown and overexpression experiments in NP cells examined SOX4 effects on ECM degradation, NLRP3-mediated pyroptosis, and mitochondrial ROS-dependent NLRP3 inflammasome activation. The involvement of the EZH2/NRF2 pathway in SOX4-mediated NLRP3 activation was also examined.

RESULTS

SOX4 expression was significantly increased in IDD rats and promoted IDD progression. Knockdown of SOX4 inhibited ECM degradation and NLRP3-mediated pyroptosis in NP cells. In vitro experiments showed that SOX4 promoted ECM degradation by upregulating MMPs and ADAMTS-5 expression, and suppressed collagen II and aggrecan synthesis. SOX4 knockdown inhibited NLRP3-mediated pyroptosis, while overexpression accelerated it in NP cells. Additionally, SOX4 was found to exacerbate mitochondrial ROS-dependent NLRP3 inflammasome activation in NP cells. Further investigation revealed that SOX4 enhanced NLRP3 inflammasome activation by upregulating EZH2 expression and modulating the EZH2/NRF2 pathway, with EZH2 inhibition attenuating SOX4-induced NLRP3 activation.

CONCLUSION

Our findings suggest that SOX4 accelerates IDD progression by promoting NLRP3 inflammasome activation via modulating the EZH2/NRF2 pathway, leading to NP cell pyroptosis and ECM degradation. Targeting SOX4 may represent a potential therapeutic strategy for treating IDD.

Mesenchymal stem cell-derived small extracellular vesicles restored nasal barrier function in allergic rhinitis via miR-143-GSK3B in human nasal epithelial cells

BACKGROUND

The nasal epithelial barrier is the first line of defense against the deep entry of pathogens or aeroallergens and is more critical in allergic rhinitis (AR). Restoring epithelial barrier dysfunction might be a promising strategy for AR. Recent studies reported that mesenchymal stem cell-derived small extracellular vesicles (MSC-sEV) potentially inhibit the inflammation response and promote tissue regeneration. However, their effect on nasal epithelial cells remains unknown.

OBJECTIVES

This study sought to describe the therapeutic effect of MSC-sEV on AR, particularly focusing their effect on nasal epithelial cells and underlying molecular mechanisms.

METHODS

We utilized an ovalbumin-induced mouse model to study AR. Both primary and immortalized human nasal epithelial cells (HNEpC) were used to further validate the therapeutic effects of MSC-sEV on epithelial cell function. Then we constructed microRNA (miR)-143 overexpressing and low-expressing HNEpC and MSC-sEV to elucidate molecular mechanisms. Transcriptome analysis was performed to identify the downstream pathways involved.

RESULTS

MSC-sEV successfully maintained nasal barrier integrity in AR mouse model. The MSC-sEV therapeutic effect on the nasal barrier was substantiated in HNEpC. Mechanistically, miR-143 was a candidate mediator of the above effects. Subsequently, transfecting HNEpC with miR-143 partially mimicked the restoring effect of MSC-sEV. MSC-sEV overexpressing miR-143 exerted more therapeutic effects on tight junctions and barrier integrity. Moreover, miR-143 regulated the glycogen synthase kinase-3β (GSK3B) pathway.

CONCLUSIONS

Our results indicated that MSC-sEV mitigated AR and restored nasal epithelial barrier dysfunction through the miR-143-GSK3B axis, which suggested that MSC-sEV have the remarkable ability to treat AR.

Region-specific mitophagy in nucleus pulposus, annulus fibrosus, and cartilage endplate of intervertebral disc degeneration: mechanisms and therapeutic strategies

Intervertebral disc degeneration (IVDD) is a prevalent condition contributing to various spinal disorders, posing a significant global health burden. Mitophagy plays a crucial role in maintaining mitochondrial quantity and quality and is closely associated with the onset and progression of IVDD. Well-documented region-specific mitophagy mechanisms in IVDD are guiding the development of therapeutic strategies. In the nucleus pulposus (NP), impaired mitochondria lead to apoptosis, oxidative stress, senescence, extracellular matrix degradation and synthesis, excessive autophagy, inflammation, mitochondrial instability, and pyroptosis, with key regulatory targets including AMPK, PGC-1α, SIRT1, SIRT3, Progerin, p65, Mfn2, FOXO3, NDUFA4L2, SLC39A7, ITGα5/β1, Nrf2, and NLRP3 inflammasome. In the annulus fibrosus (AF), mitochondrial damage induces apoptosis and oxidative stress mediated by PGC-1α, while in the cartilage endplate (CEP), mitochondrial dysfunction similarly triggers apoptosis and oxidative stress. These mechanistic insights highlight therapeutic strategies such as activating Parkin-dependent and Ub-independent mitophagy pathways for NP, enhancing Parkin-dependent mitophagy for AF, and targeting Parkin-mediated mitophagy for CEP. These strategies include the use of natural ingredients, hormonal modulation, gene editing technologies, targeted compounds, and manipulation of related proteins. This review summarizes the mechanisms of mitophagy in different regions of the intervertebral disc and highlights therapeutic approaches using mitophagy modulators to ameliorate IVDD. It discusses the complex mechanisms of mitophagy and underscores its potential as a therapeutic target. The objective is to provide valuable insights and a scientific basis for the development of mitochondrial-targeted drugs for anti-IVDD.

Causal Relationship Between Mitochondrial DNA Copy Number and Intervertebral Disc Degeneration: A Bidirectional 2-Sample Mendelian Randomization Study

OBJECTIVE

The causal relationship between mitochondrial DNA copy number (mtDNA-CN) and intervertebral disc degeneration (IVDD) remains unclear. The study aimed to investigate the causal relationship between mtDNA-CN and IVDD using Mendelian randomization (MR) analyses.

METHODS

The causal relationship between mtDNA-CN and IVDD was estimated using a bidirectional 2-sample MR method. The inverse-variance weighted method was employed as the main MR method. Sensitivity analyses were conducted to validate the robustness and reliability of the MR results.

RESULTS

The MR results by inverse-variance weighted revealed that genetically predicted mtDNA-CN was not associated with IVDD (odds ratio = 0.91; 95% confidence interval = 0.79-1.04; P = 0.1731). Similar results were observed in other 4 MR methods (P > 0.05). Heterogeneity was found in the analysis of IVDD on mtDNA-CN (P < 0.05), while no horizontal pleiotropy was observed (P > 0.05). Furthermore, the leave-one-out analysis indicated the robustness of MR results not biased by a single nucleotide polymorphism. Moreover, the reverse MR analysis did not reveal any significant causal association of IVDD on mtDNA-CN.

CONCLUSIONS

The study revealed that there is no causal relationship of mtDNA-CN on the risk of IVDD, nor does IVDD have a significant causal effect on mtDNA-CN. Although the study did not find a significant causal relationship, it provides valuable insights into the complex interplay between genetic factors and IVDD. Further research is needed to explore to better understand the underlying mechanisms of this condition.

Exploring the ncRNA landscape in exosomes: Insights into wound healing mechanisms and therapeutic applications

Exosomal non-coding RNAs (ncRNAs), including miRNAs, lncRNAs, and circRNAs, have emerged as crucial modulators in cellular signaling, influencing wound healing processes. Stem cell-derived exosomes, which serve as vehicles for these ncRNAs, show remarkable therapeutic potential due to their ability to modulate wound healing stages, from initial inflammation to collagen formation. These ncRNAs act as molecular signals, regulating gene expression and protein synthesis necessary for cellular responses in healing. Wound healing is a complex, staged process involving inflammation, hemostasis, fibroblast proliferation, angiogenesis, and tissue remodeling. Stem cell-derived exosomal ncRNAs enhance these stages by reducing excessive inflammation, promoting anti-inflammatory responses, guiding fibroblast and keratinocyte maturation, enhancing vascularization, and ensuring organized collagen deposition. Their molecular cargo, particularly ncRNAs, specifically targets pathways to aid chronic wound repair and support scarless regeneration. This review delves into the unique composition and signaling roles of Stem cell-derived exosomes and ncRNAs, highlighting their impact across wound healing stages and their potential as innovative therapeutics. Understanding the interaction between exosomal ncRNAs and cellular signaling pathways opens new avenues in regenerative medicine, positioning Stem cell-derived exosomes and their ncRNAs as promising molecular-level interventions in wound healing.

The anti-oxidation related bioactive materials for intervertebral disc degeneration regeneration and repair

Intervertebral disc degeneration (IVDD) is a prevalent chronic spinal condition characterized by the deterioration of the intervertebral discs (IVD), leading to structural damage and associated pain. This degenerative process is closely linked to oxidative stress injury, which plays a pivotal role in its onset and progression. Oxidative stress in IVDD results from the excessive production of reactive oxygen species (ROS) and impaired ROS clearance mechanisms, disrupting the redox balance within the intervertebral disc. Consequently, oxidative stress contributes to the degradation of the extracellular matrix (ECM), promotes cell apoptosis, and exacerbates disc tissue damage. Current treatment options for IVDD face significant challenges in effectively alleviating the oxidative stress-induced damage and facilitating disc tissue repair. However, recent advancements in biomaterials have opened new avenues of hope for IVDD treatment by addressing oxidative stress. In this review, we first provide an overview of the pathophysiological process of IVDD and explore the mechanisms and pathways associated with oxidative stress injury. Then, we delve into the current research on antioxidant biomaterials employed in the treatment of IVDD, and outline the advantages and limitations of hydrogel, nanomaterials, polyphenol and inorganic materials. Finally, we propose the future research direction of antioxidant biomaterials in IVDD treatment. The main idea of this review is shown in Scheme 1.

Nanomedicine Approaches for Intervertebral Disc Regeneration: From Bench to Bedside

Intervertebral disc degeneration (IDD) is a leading cause of low back pain (LBP) and neurological dysfunction, contributing significantly to disability-adjusted life years globally. The progression of IDD is driven by excessive oxidative stress, inflammation, apoptosis, and fibrosis, which disrupt the balance between anabolic and catabolic processes, leading to extracellular matrix (ECM) degradation and IDD. Current treatment options, such as conservative therapy and surgical intervention, are limited in halting the disease progression and often exacerbate degeneration in adjacent discs. This review highlights the challenges in treating IDD, particularly due to the limited drug delivery efficiency to the intervertebral disc (IVD). It explores the potential of nanobiomedicine and various nanomaterial-based delivery systems, including nanoparticles, microspheres, gene-nanocomplexes, fullerene, exosomes, and nanomaterial-composite hydrogels. These advanced delivery systems can enhance targeted drug delivery, improve local drug concentration, and sustain drug retention within the IVD, offering promising therapeutic strategies to address IDD. The review also examines the therapeutic effects of these nanomaterials on IDD, focusing on their impact on metabolism, inflammation, apoptosis, fibrosis, and stem cell migration and differentiation, aiming to provide innovative strategies for intervertebral disc regeneration.

Pyroptosis: candidate key targets for mesenchymal stem cell-derived exosomes for the treatment of bone-related diseases

Bone-related diseases impact a large portion of the global population and, due to their high disability rates and limited treatment options, pose significant medical and economic challenges. Mesenchymal stem cells (MSCs) can differentiate into multiple cell types and offer strong regenerative potential, making them promising for treating various diseases. However, issues with the immune response and cell survival limit the effectiveness of cell transplantation. This has led to increased interest in cell-free stem cell therapy, particularly the use of exosomes, which is the most studied form of this approach. Exosomes are extracellular vesicles that contain proteins, lipids, and nucleic acids and play a key role in cell communication and material exchange. Pyroptosis, a form of cell death involved in innate immunity, is also associated with many diseases. Studies have shown that MSC-derived exosomes have therapeutic potential for treating a range of conditions by regulating inflammation and pyroptosis. This study explored the role of MSC-derived exosomes in modulating pyroptosis to improve the treatment of bone-related diseases.

The Role of Extracellular Vesicles in Aging and Age-Related Disorders

A variety of molecular and cellular changes distinguish the multifaceted biological process of aging. Recent studies in this decade have demonstrated the essential role of extracellular vesicles (EVs) in the aging process. Mitochondrial malfunction and increased oxidative stress are major contributors for the aging process. This review investigates the role of EVs in intercellular communication, tissue regeneration, and inflammation in the context of aging. We also discuss the exosome and its utility to reduce oxidative stress, which is a key part of aging, as well as the possibility of using the exosomes (EVs) as anti-aging drugs. Changes in cargo composition can influence the aging phenotype and impact the functionality of cells and tissues. Additionally, the role of EVs in oxidative stress during the aging process addresses potential treatment strategies and the development of biomarkers for age-associated disorders. The review also highlighted the role of exosomes in providing antioxidant properties, which help reduce excessive reactive oxygen species (ROS) and strengthen cellular defenses against oxidative stress. Additionally, it emphasized the role of extracellular vesicles (EVs) in age-related pathologies, such as neurodegenerative diseases, cardiovascular disorders, and immunosenescence, offering insights into targeted interventions for promoting healthy aging. This article provides a comprehensive analysis of the current body of knowledge regarding the therapeutic effects of EVs on aging, with a particular emphasis on the implications of this emerging field of research and its relationship to oxidative stress.

Polysaccharide-based biomaterials for regenerative therapy in intervertebral disc degeneration

Intervertebral disc (IVD) degeneration represents a significant cause of chronic back pain and disability, with a substantial impact on the quality of life. Conventional therapeutic modalities frequently address the symptoms rather than the underlying etiology, underscoring the necessity for regenerative therapies that restore disc function. Polysaccharide-based materials, such as hyaluronic acid, alginate, chitosan, and chondroitin sulfate, have emerged as promising candidates for intervertebral disc degeneration (IVDD) therapy due to their biocompatibility, biodegradability, and ability to mimic the native extracellular matrix (ECM) of the nucleus pulposus (NP). These materials have demonstrated the capacity to support cell viability, facilitate matrix production, and alleviate inflammation in vitro and in vivo, thus supporting tissue regeneration and restoring disc function in comparison to conventional treatment. Furthermore, polysaccharide-based hydrogels have demonstrated the potential to deliver bioactive molecules, including growth factors, cytokines and anti-inflammatory drugs, directly to the degenerated disc environment, thereby enhancing therapeutic outcomes. Therefore, polysaccharide-based materials provide structural support and facilitate the regeneration of native tissue, representing a versatile and effective approach for the treatment of IVDD. Despite their promise, challenges such as limited long-term stability, potential immunogenicity, and the difficulty in scaling up production for clinical use remain. This review delineates the potential of various polysaccharides during the fabrication of hydrogels and scaffolds for disc regeneration, guiding and inspiring future research to focus on optimizing these materials for clinical translation for IVDD repair and regeneration.

Targeting NLRP3 Inflammasomes: A Trojan Horse Strategy for Intervention in Neurological Disorders

Recently, a growing focus has been on identifying critical mechanisms in neurological diseases that trigger a cascade of events, making it easier to target them effectively. One such mechanism is the inflammasome, an essential component of the immune response system that plays a crucial role in disease progression. The NLRP3 (nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain containing 3) inflammasome is a subcellular multiprotein complex that is widely expressed in the central nervous system (CNS) and can be activated by a variety of external and internal stimuli. When activated, the NLRP3 inflammasome triggers the production of proinflammatory cytokines interleukin-1β (IL-1β) and interleukin-18 (IL-18) and facilitates rapid cell death by assembling the inflammasome. These cytokines initiate inflammatory responses through various downstream signaling pathways, leading to damage to neurons. Therefore, the NLRP3 inflammasome is considered a significant contributor to the development of neuroinflammation. To counter the damage caused by NLRP3 inflammasome activation, researchers have investigated various interventions such as small molecules, antibodies, and cellular and gene therapy to regulate inflammasome activity. For instance, recent studies indicate that substances like micro-RNAs (e.g., miR-29c and mR-190) and drugs such as melatonin can reduce neuronal damage and suppress neuroinflammation through NLRP3. Furthermore, the transplantation of bone marrow mesenchymal stem cells resulted in a significant reduction in the levels of pyroptosis-related proteins NLRP3, caspase-1, IL-1β, and IL-18. However, it would benefit future research to have an in-depth review of the pharmacological and biological interventions targeting inflammasome activity. Therefore, our review of current evidence demonstrates that targeting NLRP3 inflammasomes could be a pivotal approach for intervention in neurological disorders.

CRISPR-dCas9 Activation of TSG-6 in MSCs Modulates the Cargo of MSC-Derived Extracellular Vesicles and Attenuates Inflammatory Responses in Human Intervertebral Disc Cells In Vitro

Purpose

The purpose of this study was to boost the therapeutic effect of mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) by overexpressing the gene TSG-6 through CRISPR activation, and assess the biological activity of EVs from these modified MSCs in vitro on human intervertebral disc (IVD) cells.

Methods

An immortalized human MSC line was transduced with a CRISPR activation lentivirus system targeting TSG-6. MSC-EVs were harvested by ultracentrifugation and particle number/size distribution was determined by nanoparticle tracking analysis. The efficiency of transduction activation was assessed by analyzing gene and protein expression. EV proteomic contents were analyzed by mass spectrometry. Human IVD cells from patients undergoing spinal surgery were isolated, expanded, exposed to IL-1β pre-stimulation and co-treated with MSC-EVs.

Results

MSC-EVs presented size distribution, morphology, and molecular markers consistent with common EV characteristics. The expression level of TSG-6 was significantly higher (> 800 fold) in transduced MSCs relative to controls. Protein analysis of MSCs and EVs showed higher protein expression of TSG-6 in CRISPR activated samples than controls. Proteomics of EVs identified 35 proteins (including TSG-6) that were differentially expressed in TSG-6 activated EVs vs control EVs. EV co-Treatment of IL-1β pre-Stimulated IVD cells resulted in a significant downregulation of IL-8 and COX-2.

Conclusions

We successfully generated an MSC line overexpressing TSG-6. Furthermore, we show that EVs isolated from these modified MSCs have the potential to attenuate the pro-inflammatory gene expression in IVD cells. This genomic engineering approach hence holds promise for boosting the therapeutic effects of EVs.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-025-00843-4.

The functional regulation between extracellular vesicles and the DNA damage responses

The DNA damage response (DDR) is a crucial regulatory mechanism for the survival of organisms, and irregularity of DDR may contribute to the development of various diseases, including tumors, making it is a prominent topic in therapeutic research. Extracellular vesicles (EVs), as important mediators of intercellular communication, have been extensively studied in recent years. Notably, an increasing number of studies have revealed a strong connection between DDR and EVs. On one hand, DNA damage affects the release of EVs and their compositional content; on the other hand, EVs can dictate cell survival or death by modulating DDR in both the parental and the recipient cells. This review outlines current progress in the inter-regulatory relationship between EVs and DDR, with special emphasis on the effects of EVs derived from various sources on DDR in recipient cells. In addition, the potential applications of EVs in research and tumor therapy are discussed.

Validation and the role of PDK4 relevant to ferroptosis in degenerative lumbar disc disease

BACKGROUND

Ferroptosis was involved in the pathogenesis of intervertebral disc degeneration (IVDD). However, the exact mechanism of IVDD associated with ferroptosis still required deeper studies.

METHOD

The differentially expressed genes (DEGs) in rat lumbar disc tissue between the control and IVDD group treated with IL-1β were detected by RNA sequencing (RNA-seq). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were performed on DEGs. We further screened the differential expressed ferroptosis-related genes (DEFRGs). Besides, a protein-protein interaction (PPI) network of DEFRGs was constructed by STRING database. The Cytoscape database identified significant modules and the hub genes. The loss function of PDK4 by siRNA inference was investigated in NPCs by CCK8 assay, ELISA assay, and the analysis of ferroptosis indicators.

RESULT

DEGs were identified using RNA-seq. KEGG pathway analysis showed that these genes were mainly involved in Parkinson's disease, oxytocin signaling pathway, calcium ion signaling pathway, AMPK signaling pathway, and glucagon signaling pathway. Eight hub genes (including LDHA, PKM, EP300, EGFR, EGLN1, SCD, PDK4, and FABP4) were found by the PPI network and Cytoscape on a total of 25 ferroptosis-related genes that were identified in rat lumbar disc tissue after IVDD treatment. PDK4 silencing promoted NPCS proliferation, decreased the levels of the proinflammatory factors, and suppressed ferroptosis.

CONCLUSION

The study suggested the potential roles of ferroptosis-related genes in IVDD and further revealed the role of PDK4 in the progression of IVDD.

PU.1 regulates osteoarthritis progression via CSF1R in synovial cells

This study elucidates the molecular mechanisms driving osteoarthritis (OA) by focusing on the transcription factor PU.1's role in synovial cells, specifically macrophages and fibroblast-like synoviocytes (FLS). Analyzing OA-related synovial gene expression from the GEO database highlighted immune regulation pathways in OA. Using protein-protein interaction and the JASPAR database, we pinpointed essential genes in OA development. Synovial tissues from OA patients and controls revealed pronounced PU.1 and its target CSF1R presence. In a surgically induced OA mouse model with PU.1 and CSF1R knockdown, ChIP assays confirmed PU.1's binding to the CSF1R promoter. Dual luciferase reporter assays and immunohistochemistry validated PU.1's regulatory impact on CSF1R transcription. Combined analysis of microarrays GSE55235 and GSE206848 showed heightened PU.1 expression in OA, associated with immune regulation in macrophages. In vitro findings aligned with in vivo results, emphasizing PU.1's influence on macrophage polarization and FLS-induced inflammation. PU.1's direct activation of CSF1R transcription underpins its key role in OA progression. This research offers insights into OA's molecular basis, suggesting potential therapeutic targets.

Innovating intervertebral disc degeneration therapy: Harnessing the power of extracellular vesicles

Intervertebral disc degeneration is the leading cause of low back pain, imposing significant burdens on patients, societies, and economies. Advancements in regenerative medicine have spotlighted extracellular vesicles as promising nanoparticles for intervertebral disc degeneration treatment. Extracellular vesicles retain the potential of cell therapy and serve as carriers to deliver their cargo to target cells, thereby regulating cell activity. This review summarizes the biogenesis and molecular composition of extracellular vesicles and explores their therapeutic roles in intervertebral disc degeneration treatment through various mechanisms. These mechanisms include mitigating cell loss and senescence, delaying extracellular matrix degeneration, and modulating the inflammatory microenvironment. Additionally, it highlights recent efforts in engineering extracellular vesicles to enhance their targeting and therapeutic efficacy. The integration of extracellular vesicle-based acellular therapy is anticipated to drive significant advancements in disc regenerative medicine.

The translational potential of this article

Existing clinical treatment strategies often fail to effectively address the challenges associated with regenerating degenerated intervertebral discs. As a new regenerative medicine strategy, the extracellular vesicle strategy avoids the risks associated with cell transplantation and shows great promise in treating intervertebral disc degeneration by carrying therapeutic cargo. This review comprehensively examines the latest research, underlying mechanisms, and therapeutic potential of extracellular vesicles, offering a promising new strategy for intervertebral disc degeneration treatment.

A novel cytoprotective organ perfusion platform for reconstructing homeostasis of DCD liver while alleviating IRI injury

Pump is a vital component for expelling the perfusate in small animal isolated organ normothermic machine perfusion (NMP) systems whose flexible structure and rhythmic contraction play a crucial role in maintaining perfusion system homeostasis. However, the continuous extrusion forming with the rigid stationary shaft of the peristaltic pumps can damage cells, leading to metabolic disorders and eventual dysfunction of transplanted organs. Here, we developed a novel biomimetic blood-gas system (BBGs) for preventing cell damage. This system mimics the cardiac cycle and features an adjustable inspiratory-to-expiratory (IE) ratio to mitigate acidosis caused by continuous oxygen inhalation. In our study, adipose stem cells (ADSCs) were cultured within the circulatory system for 10 min, 2, and 4 h. Compared to the peristaltic pump, the BBGs significantly reduced cell apoptosis and morphological injury while enhancing cell proliferation and adhesion. Additionally, when the supernatant from ADSCs was introduced to LPS-induced macrophages for 24 h, the BBGs group demonstrated a more pronounced anti-inflammatory effect, characterized by reduced M1 macrophage expression. Besides, with isolated rat livers from donation after circulatory death (DCD) perfusion with ADSCs for 6 h by the BBGs, we detected fewer apoptotic cells and a reduced inflammatory response, evidenced by down-regulated TNF-α expression. The development of BBGs demonstrates the feasibility of recreating physiological liquid-gas circulation in vitro, offering an alternative platform for isolated organ perfusion, especially for applications involving cell therapy.

Bone aging and extracellular vesicles

Bone aging, a major global health concern, is the natural decline in bone mass and strength. Concurrently, extracellular vesicles (EVs), tiny membrane-bound particles produced by cells, have gained recognition for their roles in various physiological processes and age-related diseases. The interaction between EVs and bone aging is of growing interest, particularly their effects on bone metabolism, which become increasingly critical with advancing age. In this review, we explored the biology, types, and functions of EVs and emphasized their regulatory roles in bone aging. We examined the effects of EVs on bone metabolism and highlighted their potential as biomarkers for monitoring bone aging progression. Furthermore, we discussed the therapeutic applications of EVs, including targeted drug delivery and bone regeneration, and addressed the challenges associated with EV-based therapies, including the technical complexities and regulatory issues. We summarized the current research and clinical trials investigating the role of EVs in bone aging and suggested future research directions. These include the potential for personalized medicine using EVs and the integration of EV research with advanced technologies to enhance the management of age-related bone health. This analysis emphasized the transformative potential of EVs in understanding and managing bone aging, thereby marking a significant advancement in skeletal health research.

Intervertebral Disc Degeneration and Regeneration: New Molecular Mechanisms and Therapeutics: Obstacles and Potential Breakthrough Technologies

Pain and disability secondary to degenerative disc disease continue to burden the healthcare system, creating an urgent need for effective, disease-modifying therapies. Contemporary research has identified potential therapies that include protein-, cellular- and/or matrix-related approaches; however, none have yet achieved a meaningful clinical impact. The tissue-specific realities of the intervertebral disc create considerable therapeutic challenges due to the disc's location, compartmentalization, hypovascularization and delicate physiological environment. Furthermore, the imaging modalities currently used in practice are largely unable to accurately identify sources of pain ostensibly discogenic in origin. These obstacles are considerable; however, recent research has begun to shed light on possible breakthrough technologies. Such breakthroughs include revolutionary imaging to better identify tissue sources of pain. Furthermore, novel molecular therapies have been shown to be able to mediate the progression of degenerative disc disease in some large animal studies, and even provide some insight into suppressing the development of tissue sources of discogenic pain. These potential breakthrough technologies have yet to be translated for clinical use.

Targeting nucleus pulposus cell death in the treatment of intervertebral disc degeneration

Background

Intervertebral disc degeneration (IDD) is a progressive age-related disorder characterized by the reduction in the number of nucleus pulposus cells (NPCs) and degradation of extracellular matrix (ECM), thereby leading to chronic pain and disability. The pathogenesis of IDD is multifaceted, and current therapeutic strategies remain limited. The nucleus pulposus (NP), primarily composed of NPCs, proteoglycans, and type II collagen, constitutes essential components for maintaining intervertebral disc (IVD) function and spinal motion. The disturbed homeostasis of NPCs is closely associated with IDD. Accumulating evidence increasingly suggests the crucial role of programmed cell death (PCD) in regulating the homeostasis of NPCs.

Aims

This review aimed to elucidate various forms of PCD and their respective roles in IDD, and investigate diverse strategies targeting the cell death of NPCs for IDD treatment.

Materials & Methods

We collected the relevant literature regarding PCD and their roles in the development of IDD. Subsequently, we comprehensively summarized the intricate association between PCD and IDD, and also explored the potential and application of cell therapy and traditional Chinese medicine (TCM) in the prevention and treatment of IDD.

Results

Current literature indicated that the PCD of NPCs was closely associated with the pathogenesis of IDD. Additionally, the development of targeted pharmaceuticals based on the mechanisms of PCD could effectively impede the loss of NPCs.

Conclusion

This review demonstrated that targeting the PCD of NPCs may be a promising strategy for the treatment of IDD.

Role of oxidative stress in mitochondrial dysfunction and their implications in intervertebral disc degeneration: Mechanisms and therapeutic strategies

Background

Intervertebral disc degeneration (IVDD) is widely recognized as one of the leading causes of low back pain. Intervertebral disc cells are the main components of the intervertebral disc (IVD), and their functions include synthesizing and secreting collagen and proteoglycans to maintain the structural and functional stability of the IVD. In addition, IVD cells are involved in several physiological processes. They help maintain nutrient metabolism balance in the IVD. They also have antioxidant and anti-inflammatory effects. Because of these roles, IVD cells are crucial in IVDD. When IVD cells are subjected to oxidative stress, mitochondria may become damaged, affecting normal cell function and accelerating degenerative changes. Mitochondria are the energy source of the cell and regulate important intracellular processes. As a key site for redox reactions, excessive oxidative stress and reactive oxygen species can damage mitochondria, leading to inflammation, DNA damage, and apoptosis, thus accelerating disc degeneration.

Aim of review

Describes the core knowledge of IVDD and oxidative stress. Comprehensively examines the complex relationship and potential mechanistic pathways between oxidative stress, mitochondrial dysfunction and IVDD. Highlights potential therapeutic targets and frontier therapeutic concepts. Draws researchers' attention and discussion on the future research of all three.

Key scientific concepts of review

Origin, development and consequences of IVDD, molecular mechanisms of oxidative stress acting on mitochondria, mechanisms of oxidative stress damage to IVD cells, therapeutic potential of targeting mitochondria to alleviate oxidative stress in IVDD.

The translational potential of this article

Targeted therapeutic strategies for oxidative stress and mitochondrial dysfunction are particularly critical in the treatment of IVDD. Using antioxidants and specific mitochondrial therapeutic agents can help reduce symptoms and pain. This approach is expected to significantly improve the quality of life for patients. Individualized therapeutic approaches, on the other hand, are based on an in-depth assessment of the patient's degree of oxidative stress and mitochondrial functional status to develop a targeted treatment plan for more precise and effective IVDD management. Additionally, we suggest preventive measures like customized lifestyle changes and medications. These are based on understanding how IVDD develops. The aim is to slow down the disease and reduce the chances of it coming back. Actively promoting clinical trials and evaluating the safety and efficacy of new therapies helps translate cutting-edge treatment concepts into clinical practice. These measures not only improve patient outcomes and quality of life but also reduce the consumption of healthcare resources and the socio-economic burden, thus having a positive impact on the advancement of the IVDD treatment field.

Food-derived vesicles as immunomodulatory drivers: Current knowledge, gaps, and perspectives

Extracellular vesicles (EVs) are lipid-bound membrane vesicles released from cells, containing active compounds, which can be found in different foods. In this review, the role of food-derived vesicles (FDVs) as immunomodulatory drivers is summarized, with a focus on sources, isolation techniques and yields, as well as bioavailability and potential health implications. In addition, gaps and perspectives detected in this research field have been highlighted. FDVs have been efficiently extracted from different sources, and differential ultracentrifugation seems to be the most adequate isolation technique, with yields ranging from 108 to 1014 EV particles/mL. Animal studies show promising results in how these FDVs might regulate different pathways related to inflammation. Further investigation on the production of stable components in a cost-effective way, as well as human studies demonstrating safety and health-promoting properties, since scarce information has been reported until now, in the context of modulating the immune system are needed.

Mitochondrial Extracellular Vesicles (mitoEVs): Emerging mediators of cell-to-cell communication in health, aging and age-related diseases

Mitochondria are metabolic and signalling hubs that integrate a plethora of interconnected processes to maintain cell homeostasis. They are also dormant mediators of inflammation and cell death, and with aging damages affecting mitochondria gradually accumulate, resulting in the manifestation of age-associated disorders. In addition to coordinate multiple intracellular functions, mitochondria mediate intercellular and inter-organ cross talk in different physiological and stress conditions. To fulfil this task, mitochondrial signalling has evolved distinct and complex conventional and unconventional routes of horizontal/vertical mitochondrial transfer. In this regard, great interest has been focused on the ability of extracellular vesicles (EVs), such as exosomes and microvesicles, to carry selected mitochondrial cargoes to target cells, in response to internal and external cues. Over the past years, the field of mitochondrial EVs (mitoEVs) has grown exponentially, revealing unexpected heterogeneity of these structures associated with an ever-expanding mitochondrial function, though the full extent of the underlying mechanisms is far from being elucidated. Therefore, emerging subsets of EVs encompass exophers, migrasomes, mitophers, mitovesicles, and mitolysosomes that can act locally or over long-distances to restore mitochondrial homeostasis and cell functionality, or to amplify disease. This review provides a comprehensive overview of our current understanding of the biology and trafficking of MitoEVs in different physiological and pathological conditions. Additionally, a specific focus on the role of mitoEVs in aging and the onset and progression of different age-related diseases is discussed.

Current Therapeutic Strategies of Intervertebral Disc Regenerative Medicine

Intervertebral disc degeneration (IDD) is one of the most frequent causes of low back pain. No treatment is currently available to delay the progression of IDD. Conservative treatment or surgical interventions is only used to target the symptoms of IDD rather than treat the underlying cause. Currently, numerous potential therapeutic strategies are available, including molecular therapy, gene therapy, and cell therapy. However, the hostile environment of degenerated discs is a major problem that has hindered the clinical applicability of such approaches. In this regard, the design of drugs using alternative delivery systems (macro-, micro-, and nano-sized particles) may resolve this problem. These can protect and deliver biomolecules along with helping to improve the therapeutic effect of drugs via concentrating, protecting, and prolonging their presence in the degenerated disc. This review summarizes the research progress of diagnosis and the current options for treating IDD.

Mitochondrial transplantation: a promising strategy for treating degenerative joint diseases

The prevalence of age-related degenerative joint diseases, particularly intervertebral disc degeneration and osteoarthritis, is increasing, thereby posing significant challenges for the elderly population. Mitochondrial dysfunction is a critical factor in the etiology and progression of these disorders. Therapeutic interventions that incorporate mitochondrial transplantation exhibit considerable promise by increasing mitochondrial numbers and improving their functionality. Existing evidence suggests that exogenous mitochondrial therapy improves clinical outcomes for patients with degenerative joint diseases. This review elucidates the mitochondrial abnormalities associated with degenerative joint diseases and examines the mechanisms of mitochondrial intercellular transfer and artificial mitochondrial transplantation. Furthermore, therapeutic strategies for mitochondrial transplantation in degenerative joint diseases are synthesized, and the concept of engineered mitochondrial transplantation is proposed.

Exosomes Derived from Rejuvenated Stem Cells Inactivate NLRP3 Inflammasome and Pyroptosis of Nucleus Pulposus Cells via the Transfer of Antioxidants

BACKGROUND

Accumulating evidence supports the potential of exosomes as a promising therapeutic approach for intervertebral disc degeneration (IDD). Nevertheless, enhancing the efficiency of exosome treatment remains an urgent concern. This study investigated the impact of quercetin on the characteristics of mesenchymal stem cells (MSCs) and their released exosomes.

METHODS

Exosomes were obtained from quercetin pre-treated MSCs and quantified for the production based on nanoparticle tracking and western blot analysis. The molecules involved in the secretion and cargo sorting of exosomes were investigated using western blot and immunofluorescence analysis. Based on the in vitro biological analysis and in vivo histological analysis, the effects of exosomes derived from conventional or quercetin-treated MSCs on nucleus pulposus (NP) cells were compared.

RESULTS

A significant enhancement in the production and transportation efficiency of exosomes was observed in quercetin-treated MSCs. Moreover, the exosomes derived from quercetin-treated MSCs exhibited a greater abundance of antioxidant proteins, specifically superoxide dismutase 1 (SOD1), which inhibit the activation of NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome in NP cells. Through in vitro and in vivo experiments, it was elucidated that exosomes derived from quercetin-treated MSCs possessed enhanced anti-inflammatory and antioxidant properties.

CONCLUSION

Collectively, our research underscores an optimized therapeutic strategy for IDD utilizing MSC-derived exosomes, thereby augmenting the efficacy of exosomes in intervertebral disc regeneration.

Exosome is a Fancy Mobile Sower of Ferroptosis

Exosomes, nano-sized small extracellular vesicles, have been shown to serve as mediators between intercellular communications by transferring bioactive molecules, such as non-coding RNA, proteins, and lipids from secretory to recipient cells, modulating a variety of physiological and pathophysiological processes. Recent studies have gradually demonstrated that altered exosome charges may represent a key mechanism driving the pathological process of ferroptosis. This review summarizes the potential mechanisms and signal pathways relevant to ferroptosis and then discusses the roles of exosome in ferroptosis. As well as transporting iron, exosomes may also indirectly convey factors related to ferroptosis. Furthermore, ferroptosis may be transmitted to adjacent cells through exosomes, resulting in cascading effects. It is expected that further research on exosomes will be conducted to explore their potential in ferroptosis and will lead to the creation of new therapeutic avenues for clinical diseases.

Mapping knowledge structure and themes trends of non-surgical treatment in intervertebral disc degeneration

Background

Intervertebral disc degeneration (IDD) is a chronic disabling disease caused by degeneration of nucleus pulposus cells, decreased activity and the number of nucleus pulposus cells, decreased extracellular matrix, and infiltration of inflammatory factors, resulting in low back and leg pain. Recent studies have shown that non-surgical treatment is of great significance in reversing the progression of degenerative disc disease, and there are more relevant literature reports. However, there is no bibliometric analysis in this area. This study aimed to describe the knowledge structure and thematic trends of non-surgical treatment methods for IDD through bibliometrics.

Methods

Articles and reviews on non-surgical treatment of disc degeneration from 1998 to 2022 were collected on the Web of Science. VOSviewer 1.6.18, CiteSpace 6.1.R3, R package "bibliometrix" and two online analysis platforms were used for bibliometric and visual literature analysis.

Results

961 articles were screened for inclusion, including 821 articles and 140 reviews. The analysis of our study shows that publications in the non-surgical treatment of disc degeneration are increasing annually, with publications coming mainly from North America and Asia, with China and the United States dominating. Huazhong Univ Sci & Technol and Wang K are the most prolific institutions and authors, respectively, and Le Maitre CL is the most co-cited author. However, there is less collaboration between institutions in different countries. Spine is both the most published and the most cited journal. According to the co-citation and co-occurrence analysis results, "mesenchymal stem cells," "exosomes," "medication," and "tissue engineering" are the current research hotspots in this field.

Conclusions

This study employs bibliometric analysis to explore the knowledge structure and trends of non-surgical treatments for IDD from 2013 to 2022. Key research hotspots include mesenchymal stem cells, exosomes, medication, and tissue engineering. The number of publications, especially from China and the USA, has increased significantly, though international collaboration needs improvement. Influential contributors include Wang K and the journal Spine. These findings provide a comprehensive overview and highlight important future directions for the field.

Molecular mechanisms of EGCG-CSH/n-HA/CMC in promoting osteogenic differentiation and macrophage polarization

2. This research investigates the impact of the EGCG-CSH/n-HA/CMC composite material on bone defect repair, emphasizing its influence on macrophage polarization and osteogenic differentiation of BMSCs. Comprehensive evaluations of the composite's physical and chemical characteristics were performed. BMSC response to the material was tested in vitro for proliferation, migration, and osteogenic potential. An SD rat model was employed for in vivo assessments of bone repair efficacy. Both transcriptional and proteomic analyses were utilized to delineate the mechanisms influencing macrophage behavior and stem cell differentiation. The material maintained excellent structural integrity and significantly promoted BMSC functions critical to bone healing. In vivo results confirmed accelerated bone repair, and molecular analysis highlighted the role of macrophage M2 polarization, particularly through changes in the SIRPA gene and protein expression. EGCG-CSH/n-HA/CMC plays a significant role in enhancing bone repair, with implications for macrophage and BMSC function. Our findings suggest that targeting SIRPA may offer new therapeutic opportunities for bone regeneration.

Pyroptosis in Skeleton Diseases: A Potential Therapeutic Target Based on Inflammatory Cell Death

Skeletal disorders, including fractures, osteoporosis, osteoarthritis, rheumatoid arthritis, and spinal degenerative conditions, along with associated spinal cord injuries, significantly impair daily life and impose a substantial burden. Many of these conditions are notably linked to inflammation, with some classified as inflammatory diseases. Pyroptosis, a newly recognized form of inflammatory cell death, is primarily triggered by inflammasomes and executed by caspases, leading to inflammation and cell death through gasdermin proteins. Emerging research underscores the pivotal role of pyroptosis in skeletal disorders. This review explores the pyroptosis signaling pathways and their involvement in skeletal diseases, the modulation of pyroptosis by other signals in these conditions, and the current evidence supporting the therapeutic potential of targeting pyroptosis in treating skeletal disorders, aiming to offer novel insights for their management.

Unveiling the Therapeutic Potential of hUCMSC-Derived EVs in Intervertebral Disc Degeneration through MALAT1/miR-138-5p/SLC7A11 Coexpression Regulation

Intervertebral disc degeneration (IVDD) is a prevalent chronic condition causing spinal pain and functional impairment. This study investigates the role of extracellular vesicles (EVs) derived from human umbilical cord mesenchymal stem cells (hUCMSCs) in regulating IVDD. Using RNA-seq, we analyzed differential expressions of lncRNA and miRNA in nucleus pulposus tissues from various mouse groups. We identified key regulatory molecules, MALAT1 and miRNA-138-5p, which contribute to IVDD. Further experiments demonstrated that MALAT1 can up-regulate SLC7A11 expression by competitively binding to miR-138-5p, forming a MALAT1/miR-138-5p/SLC7A11 coexpression regulatory network. This study elucidates the molecular mechanism by which hUCMSC-derived EVs regulate IVDD and could help develop novel therapeutic strategies for treating this condition. Our findings demonstrate that hUCMSCs-EVs inhibit ferroptosis in nucleus pulposus cells, thereby improving IVDD. These results highlight the therapeutic potential of hUCMSCs-EVs in ameliorating the development of IVDD, offering significant scientific and clinical implications for new treatments.

Extracellular vesicles meet mitochondria: Potential roles in regenerative medicine

Extracellular vesicles (EVs), secreted by most cells, act as natural cell-derived carriers for delivering proteins, nucleic acids, and organelles between cells. Mitochondria are highly dynamic organelles responsible for energy production and cellular physiological processes. Recent evidence has highlighted the pivotal role of EVs in intercellular mitochondrial content transfer, including mitochondrial DNA (mtDNA), proteins, and intact mitochondria. Intriguingly, mitochondria are crucial mediators of EVs release, suggesting an interplay between EVs and mitochondria and their potential implications in physiology and pathology. However, in this expanding field, much remains unknown regarding the function and mechanism of crosstalk between EVs and mitochondria and the transport of mitochondrial EVs. Herein, we shed light on the physiological and pathological functions of EVs and mitochondria, potential mechanisms underlying their interactions, delivery of mitochondria-rich EVs, and their clinical applications in regenerative medicine.

Engineering extracellular vesicles for ROS scavenging and tissue regeneration

Stem cell therapy holds promise for tissue regeneration, yet significant challenges persist. Emerging as a safer and potentially more effective alternative, extracellular vesicles (EVs) derived from stem cells exhibit remarkable abilities to activate critical signaling cascades, thereby facilitating tissue repair. EVs, nano-scale membrane vesicles, mediate intercellular communication by encapsulating a diverse cargo of proteins, lipids, and nucleic acids. Their therapeutic potential lies in delivering cargos, activating signaling pathways, and efficiently mitigating oxidative stress-an essential aspect of overcoming limitations in stem cell-based tissue repair. This review focuses on engineering and applying EVs in tissue regeneration, emphasizing their role in regulating reactive oxygen species (ROS) pathways. Additionally, we explore strategies to enhance EV therapeutic activity, including functionalization and incorporation of antioxidant defense proteins. Understanding these molecular mechanisms is crucial for optimizing EV-based regenerative therapies. Insights into EV and ROS signaling modulation pave the way for targeted and efficient regenerative therapies harnessing the potential of EVs.

Secretome profiling reveals acute changes in oxidative stress, brain homeostasis, and coagulation following short-duration spaceflight

As spaceflight becomes more common with commercial crews, blood-based measures of crew health can guide both astronaut biomedicine and countermeasures. By profiling plasma proteins, metabolites, and extracellular vesicles/particles (EVPs) from the SpaceX Inspiration4 crew, we generated "spaceflight secretome profiles," which showed significant differences in coagulation, oxidative stress, and brain-enriched proteins. While >93% of differentially abundant proteins (DAPs) in vesicles and metabolites recovered within six months, the majority (73%) of plasma DAPs were still perturbed post-flight. Moreover, these proteomic alterations correlated better with peripheral blood mononuclear cells than whole blood, suggesting that immune cells contribute more DAPs than erythrocytes. Finally, to discern possible mechanisms leading to brain-enriched protein detection and blood-brain barrier (BBB) disruption, we examined protein changes in dissected brains of spaceflight mice, which showed increases in PECAM-1, a marker of BBB integrity. These data highlight how even short-duration spaceflight can disrupt human and murine physiology and identify spaceflight biomarkers that can guide countermeasure development.

Therapeutic potential of mesenchymal stem cell-derived exosomes in skeletal diseases

Skeletal diseases impose a considerable burden on society. The clinical and tissue-engineering therapies applied to alleviate such diseases frequently result in complications and are inadequately effective. Research has shifted from conventional therapies based on mesenchymal stem cells (MSCs) to exosomes derived from MSCs. Exosomes are natural nanocarriers of endogenous DNA, RNA, proteins, and lipids and have a low immune clearance rate and good barrier penetration and allow targeted delivery of therapeutics. MSC-derived exosomes (MSC-exosomes) have the characteristics of both MSCs and exosomes, and so they can have both immunosuppressive and tissue-regenerative effects. Despite advances in our knowledge of MSC-exosomes, their regulatory mechanisms and functionalities are unclear. Here we review the therapeutic potential of MSC-exosomes for skeletal diseases.

A natural hydrogel complex improves intervertebral disc degeneration by correcting fatty acid metabolism and inhibiting nucleus pulposus cell pyroptosis

The degeneration of intervertebral discs is strongly associated with the occurrence of pyroptosis in nucleus pulposus (NP) cells. This pyroptosis is characterized by abnormal metabolism of fatty acids in the degenerative pathological state, which is further exacerbated by the inflammatory microenvironment and degradation of the extracellular matrix. In order to address this issue, we have developed a fibrin hydrogel complex (FG@PEV). This intricate formulation amalgamates the beneficial attributes of platelet extravasation vesicles, contributing to tissue repair and regeneration. Furthermore, this complex showcases exceptional stability, gradual-release capabilities, and a high degree of biocompatibility. In order to substantiate the biological significance of FG@PEV in intervertebral disc degeneration (IVDD), we conducted a comprehensive investigation into its potential mechanism of action through the integration of RNA-seq sequencing and metabolomics analysis. Furthermore, these findings were subsequently validated through experimentation in both in vivo and in vitro models. The experimental results revealed that the FG@PEV intervention possesses the capability to reshape the inflammatory microenvironment within the disc. It also addresses the irregularities in fatty acid metabolism of nucleus pulposus cells, consequently hindering cellular pyroptosis and slowing down disc degeneration through the regulation of extracellular matrix synthesis and degradation. As a result, this injectable gel system represents a promising and innovative therapeutic approach for mitigating disc degeneration.

An exosomal approach for oral delivery of resveratrol: Implications for inflammatory bowel disease treatment in rat model

AIMS

Resveratrol (RSV) is a polyphenolic substance found in numerous natural products. Despite the wide range of therapeutic activities, including antioxidant and anti-inflammatory effects, the poor pharmacokinetic characteristics decrease the RSV bioavailability following oral administration. Milk-derived exosomes (MEXOs), as a class of natural nanocarriers, are promising candidates for oral drug delivery approaches.

MAIN METHODS

The current study developed RSV-loaded MEXOs to enhance the RSV oral bioavailability, introducing a suitable exosomal formulation for suppressing colon inflammation in acetic acid-induced rat models.

KEY FINDINGS

The results showed a remarkable encapsulation efficiency of 83.33 %. The in vitro release profile demonstrated a good retaining capability in acidic conditions (pH 1.2) and a considerable release in a simulated duodenal environment (pH 6.8). According to the permeability study, encapsulation of RSV improved its transportation across the Caco-2 monolayer. Moreover, the in vivo and histological analysis results proved that the RSV-MEXOs formulation successfully alleviates the inflammation in colitis rat models and effectively relieves the colitis.

SIGNIFICANCE

Our findings suggest that MEXOs should be of great attention as promising oral drug delivery vehicles for further clinical evaluations.

What is the rationale for mesenchymal stromal cells based therapies in the management of hemophilic arthropathies?

Hemophilia A and B are rare X-linked genetic bleeding disorders due to a complete or partial deficiency in the coagulation factors VIII or IX, respectively. The main treatment for hemophilia is prophylactic and based on coagulation factor replacement therapies. These treatments have significantly reduced bleeding and improved the patients' quality of life. Nevertheless, repeated joint bleedings (hemarthroses), even subclinical hemarthroses, can lead to hemophilic arthropathy (HA). This disabling condition is characterized by chronic pain due to synovial inflammation, cartilage and bone destruction requiring ultimately joint replacement. HA resembles to rheumatoid arthritis because of synovitis but HA is considered as having similarities with osteoarthritis as illustrated by the migration of immune cells, production of inflammatory cytokines, synovial hypertrophy and cartilage damage. Various drugs have been evaluated for the management of HA with limited success. The objective of the review is to discuss new therapeutic approaches with a special focus on the studies that have investigated the potential of using mesenchymal stromal cells (MSCs) in the management of HA. A systematic review of the literature has been made. Most of the studies have focused on the interest of MSCs for the delivery of missing factors VIII or IX but in some studies, more insight on the effect of MSC injection on synovial inflammation or cartilage structure were provided and put in perspective for possible clinical applications.

Selenomethionine preconditioned mesenchymal stem cells derived extracellular vesicles exert enhanced therapeutic efficacy in intervertebral disc degeneration

Extracellular vesicles (EVs) derived from Mesenchymal Stromal Cells (MSCs) have shown promising therapeutic potential for multiple diseases, including intervertebral disc degeneration (IDD). Nevertheless, the limited production and unstable quality of EVs hindered the clinical application of EVs in IDD. Selenomethionine (Se-Met), the major form of organic selenium present in the cereal diet, showed various beneficial effects, including antioxidant, immunomodulatory and anti-apoptotic effects. In the current study, Se-Met was employed to treat MSCs to investigate whether Se-Met can facilitate the secretion of EVs by MSCs and optimize their therapeutic effects on IDD. On the one hand, Se-Met promoted the production of EVs by enhancing the autophagy activity of MSCs. On the other hand, Se-Met pretreated MSC-derived EVs (Se-EVs) exhibited an enhanced protective effects on alleviating nucleus pulposus cells (NPCs) senescence and attenuating IDD compared with EVs isolated from control MSCs (C-EVs) in vitro and in vivo. Moreover, we performed a miRNA microarray sequencing analysis on EVs to explore the potential mechanism of the protective effects of EVs. The result indicated that miR-125a-5p is markedly enriched in Se-EVs compared to C-EVs. Further in vitro and in vivo experiments revealed that knockdown of miR-125a-5p in Se-EVs (miRKD-Se-EVs) impeded the protective effects of Se-EVs, while overexpression of miR-125a-5p (miROE-Se-EVs) boosted the protective effects. In conclusion, Se-Met facilitated the MSC-derived EVs production and increased miR-125a-5p delivery in Se-EVs, thereby improving the protective effects of MSC-derived EVs on alleviating NPCs senescence and attenuating IDD.

Identification of key eRNAs for intervertebral disc degeneration by integrated multinomial bioinformatics analysis

BACKGROUND

Intervertebral disc degeneration (IVDD) is a common degenerative condition leading to abnormal stress distribution under load, causing intervertebral stenosis, facet joint degeneration, and foraminal stenosis. Very little is known about the molecular mechanism of eRNAs in IVDD.

METHODS

Gene expression profiles of 38 annulus disc samples composed of 27 less degenerated discs (LDs) and 11 more degenerated discs (MDs) were retrieved from the GEO database. Then, differentially expressed enhancer RNAs (DEeRNAs), differentially expressed target genes (DETGs), and differentially expressed transcription factors (DETFs), hallmark of cancer signalling pathways according to GSVA; the types and quantity of immune cells according to CIBERSORT; and immune gene sets according to ssGSEA were analysed to construct an IVDD-related eRNA network. Then, multidimensional validation was performed to explore the interactions among DEeRNAs, DETFs and DEGs in space.

RESULTS

A total of 53 components, 14 DETGs, 15 DEeRNAs, 3 DETFs, 5 immune cells, 9 hallmarks, and 7 immune gene sets, were selected to construct the regulatory network. After validation by online multidimensional databases, 21 interactive DEeRNA-DEG-DETF axes related to IVDD exacerbation were identified, among which the C1S-CTNNB1-CHD4 axis was the most significant.

CONCLUSION

Based upon the results of our study, we theorize that the C1S-CTNNB1-CHD4 axis plays a vital role in IVDD exacerbation. Specifically, C1S recruits CTNNB1 and upregulates the expression of CHD4 in IVDD, and subsequently, CHD4 suppresses glycolysis and activates oxidative phosphorylation, thus generating insoluble collagen fibre deposits and leading to the progression of IVDD. Overall, these DEeRNAs could comprise promising therapeutic targets for IVDD due to their high tissue specificity.

Exosomes from umbilical cord mesenchymal stem cells ameliorate intervertebral disc degeneration via repairing mitochondrial dysfunction

Background

Reactive oxygen species (ROS), predominantly generated by mitochondria, play a crucial role in the pathogenesis of intervertebral disc degeneration (IVDD). Reduction of ROS levels may be an effective strategy to delay IVDD. In this study, we assessed whether umbilical cord mesenchymal stem cell-exosomes (UCMSC-exos) can be used to treat IVDD by suppressing ROS production caused by mitochondrial dysfunction.

Materials and methods

Human UCMSC-exos were isolated and identified. Nucleus pulposus cells (NPCs) were stimulated with H2O2 in the presence or absence of exosomes. Then, 4D label free quantitative (4D-LFQ) proteomics were used to analyze the differentially expressed (DE) proteins. Mitochondrial membrane potential (MMP), mitochondrial ROS and protein levels were determined via immunofluorescence staining, flow cytometry and western blotting respectively. Additionally, high-throughput sequencing was performed to identify the DE miRNAs in NPCs. Finally, therapeutic effects of UCMSC-exos were investigated in a puncture-induced IVDD rat model. Degenerative grades of rat IVDs were assessed using magnetic resonance imaging and histochemical staining.

Results

UCMSC-exos effectively improved the viability of NPCs and restored the expression of the extracellular matrix (ECM) proteins, collagen type II alpha-1 (COL2A1) and matrix metalloproteinase-13 induced by H2O2. Additionally, UCMSC-exos not only reduced the total intracellular ROS and mitochondrial superoxide levels, but also increased MMP in pathological NPCs. 4D-LFQ proteomics and western blotting further revealed that UCMSC-exos up-regulated the levels of the mitochondrial protein, mitochondrial transcription factor A (TFAM), in H2O2-induced NPCs. High-throughput sequencing and qRT-PCR uncovered that UCMSC-exos down-regulated the levels of miR-194-5p, a potential negative regulator of TFAM, induced by H2O2. Finally, in vivo results showed that UCMSC-exos injection improved the histopathological structure and enhanced the expression levels of COL2A1 and TFAM in the rat IVDD model.

Conclusions

Our findings suggest that UCMSC-exos promote ECM synthesis, relieve mitochondrial oxidative stress, and attenuate mitochondrial dysfunction in vitro and in vivo, thereby effectively treating IVDD.

The translational potential of this article

This study provides solid experimental data support for the therapeutic effects of UCMSC-exos on IVDD, suggesting that UCMSC-exos will be a promising nanotherapy for IVDD.

BMSC-Derived Exosomes Attenuate Rat Osteoarthritis by Regulating Macrophage Polarization through PINK1/Parkin Signaling Pathway

OBJECTIVE

Exosomes derived from bone marrow mesenchymal stem cells (BMSC-Exos) may modulate the M1/M2 polarization of macrophages during osteoarthritis (OA). However, the underlying mechanisms of BMSC-Exos in this process still need to be elucidated. In this study, we explored the role of BMSC-Exos in the polarization of macrophages in vitro and the OA rats in vivo.

METHODS

The effects of BMSC-Exos on RAW264.7 cells were determined, including the production of reactive oxygen species (ROS) and the protein expression of Akt, PINK1, and Parkin. We prepared an OA model by resecting the anterior cruciate ligament and medial meniscus of Sprague-Dawley (SD) rats. Hematoxylin-eosin (H&E) and safranin O-fast green staining, immunohistochemistry and immunofluorescence analyses, and the examination of interleukin 6 (IL-6), interleukin 1β (IL-1β), tumor necrosis factor alpha (TNF-α), and interleukin 10 (IL-10) were performed to assess changes in cartilage and synovium.

RESULTS

BMSC-Exos inhibited mitochondrial membrane damage, ROS production, and the protein expression of PINK1 and Parkin. Akt phosphorylation was downregulated under lipopolysaccharide (LPS) induction but significantly recovered after treatment with BMSC-Exos. BMSC-Exos alleviated cartilage damage, inhibited M1 polarization, and promoted M2 polarization in the synovium in OA rats. The expression of PINK1 and Parkin in the synovium and the levels of IL-6, IL-1β, and TNF-α in the serum decreased, but the level of IL-10 increased when BMSC-Exos were used in OA rats.

CONCLUSION

BMSC-Exos ameliorate OA development by regulating synovial macrophage polarization, and one of the underlying mechanisms may be through inhibiting PINK1/Parkin signaling.