Small extracellular vesicles from young adipose-derived stem cells prevent frailty, improve health span, and decrease epigenetic age in old mice

Fate reversal: Exosome-driven macrophage rejuvenation and bacterial-responsive drug release for infection immunotherapy in diabetes

Superficial surgical site infection (SSI) is a significant risk factor for the development of periprosthetic joint infection (PJI), particularly in diabetic patients. A high-glucose microenvironment is observed to compromise phagocytosis by inducing cellular senescence, which leads to impaired antibacterial immune function. Exosomes derived from umbilical cord stem cells (H-Exos) can reverse the immunosuppressive microenvironment by rejuvenating senescent cells, thereby terminating excessive, persistent, and ineffective inflammatory responses. Thus, a novel exosome-based immunotherapeutic antibacterial strategy to reverse fate is proposed. Vancomycin & lysostaphin-loaded exosomes are incorporated in a customizable microneedle patch (ExoV-ExoL@MN) for controlled release, enabling tailored treatments for diverse clinical scenarios. While rejuvenating macrophage senescent phenotype, the antibiotics encapsulated within exosomes can be responsively released by the hemolysin secreted by bacteria, triggering rapid bacterial killing. Post-infection clearance, they induce a shift from M1 to M2 macrophage polarization, thereby enhancing anti-inflammatory and reparative responses. Furthermore, the components can be mixed on demand and at any time, allowing for real-time customization and fabrication directly at the clinic (fabrication@clinic). This strategy reverses the immunosuppressive microenvironment by rejuvenating senescent macrophages and effectively combats bacterial invasion into deep tissues through bacteria-responsive antibiotic release, providing a promising approach for preventing and treating SSI-induced PJI.

Matrix viscoelasticity drives cell cluster formation to counteract cellular senescence

During tissue repair, stress-induced cellular senescence represents a critical factor that impedes the regenerative potential of tissues. While the regulatory effects of matrix viscoelasticity on cellular behavior have been documented, their role and correlated mechanisms underlying cellular senescence remain unclear. In this study, we engineered a viscoelastic gel matrix exhibiting a storage modulus of approximately 3 kPa, with a tunable loss modulus ranging from 0 to 300 Pa by incorporating linear alginate and modulating the compactness of a polyacrylamide-based covalent network. Utilizing a UV-induced senescence model, we observed that increasing the matrix's viscoelasticity from 0 Pa to 300 Pa led to a significant reduction in the proportion of senescent cells, from 90.5% to 22.7%. Furthermore, cells cultured in these matrices exhibited a tendency to form cell aggregation, with the cell populations demonstrating a collective resistance to stresses. This indicated that viscoelastic materials would promote enhanced cellular interactions, thereby strengthening cellular resilience against UV-induced stresses. Furthermore, combined with microarray analysis, it was concluded that the presence of viscoelastic components activated the connexin 43 (Cx43)-modulated gap junction for cluster formation, thereby suppressing the senescence-associated signaling pathways, including Wnt/β-catenin, MAPK, NF-κB, and TGF-β. Additionally, the integrin-cytoskeleton-Yes-associated protein (YAP) signaling axis played an active role in delaying cell aging. These results provide novel insights into the regulatory role of viscoelastic materials in cellular senescence and offer a compelling foundation for the development of advanced biomaterials for tissue repair.

Exploring adipose tissue-derived extracellular vesicles in inter-organ crosstalk: Implications for metabolic regulation and adipose tissue function

Intercellular and inter-organ communication systems are vital for tissue homeostasis and disease development, utilizing soluble bioactive molecules for signaling. The field of extracellular vesicle (EV) biology has rapidly expanded in recent decades, highlighting EVs as effective bioactive nanovectors for cell-to-cell communication in various physiological and pathological contexts. Numerous studies indicate that adipocyte-derived EVs are crucial components of the adipose secretome, playing a key role in autocrine and paracrine interactions within adipose tissue, as well as in endocrine signaling. This review aims to present an updated perspective on EVs as mediators of communication between adipose tissue and other organs, while also examining their therapeutic potential in the light of recent advancements in EV biology research.

Targeting Muscle Regeneration with Small Extracellular Vesicles from Adipose Tissue-Derived Stem Cells-A Review

Extracellular vesicles (EVs) are membrane-bound structures released by cells carrying diverse biomolecules involved in intercellular communication. Small EVs are abundant in body fluids, playing a key role in cell signaling. Their natural occurrence and therapeutic potential, especially in the context of muscular disorders, make them a significant area of research. Sarcopenia, characterized by progressive muscle fiber loss, represents a pathological state in which EVs could offer therapeutic benefits, reducing morbidity and mortality. Recent studies have proposed an interplay between adipose tissue (AT) and skeletal muscle regarding sarcopenia pathology. AT dysregulation, as seen in obesity, contributes to skeletal muscle loss in a multifactorial way. While AT-derived stem cell (ATDSC) small EVs have been implicated in musculoskeletal homeostasis, their precise action in muscle regeneration remains incompletely understood. In this context, ATDSC-derived small EVs can stimulate skeletal muscle regeneration through improved proliferation and migration of muscle cells, enhancement of muscular perfusion, improvement of tendon and nerve regeneration, stimulation of angiogenesis, and promotion of myogenic differentiation. However, they can also increase skeletal muscle loss. Notably, this is the first comprehensive review to systematically examine the role of ATDSC-derived small EVs in sarcopenia.

Therapeutic application of extracellular vesicles in human diseases

Extracellular vesicles (EVs) are membrane vesicles released or secreted from almost all cell types. EVs are derived from multivesicular bodies or from the plasma membrane and contain a subset of proteins, lipids, and nucleic acids (e.g., DNA, RNA, and microRNA [miRNA]) derived from the parent cell. EVs play important roles in intercellular communication by efficiently transferring the content between cells both locally and systemically. Given their natural ability to transfer cargo to cells, sometimes in a targeted manner, and their apparent lack of immunogenicity, EVs are being engineered for delivery of therapeutic RNAs, DNAs, miRNAs, viral particles, drugs, and even proteins. In addition, many of the therapeutic effects of stem cell treatments are mediated by stem cell-derived EVs, which are safer and potentially more effective than the parental stem cells. Here we provide an overview of the use of EVs for delivery of different therapeutic nucleic acids, viruses, and drugs, as well as the use of therapeutic stem cell-derived EVs.

Extracellular Vesicles as Epigenetic Regulators of Redox Homeostasis: A Systematic Review and Meta-Analysis

Extracellular vesicles (EVs) are emerging as key regulators of cellular communication, with increasing evidence supporting their role in oxidative stress (OS) modulation. In particular, the miRNA cargo of EVs plays a crucial role in mitigating OS and promoting redox balance through both direct antioxidant effects and epigenetic regulation. This study aimed to evaluate the impact of EVs on OS markers, influenced by their miRNA-mediated effects and potential epigenetic modifications in target cells. A systematic literature search was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines to identify studies reporting the effects of EVs on OS parameters. A meta-analysis was performed on key OS biomarkers, including reactive oxygen species (ROS), superoxide dismutase (SOD), glutathione (GSH), and malondialdehyde (MDA). The heterogeneity of EV isolation and characterization techniques was also analyzed. The included studies demonstrated that EVs exert significant antioxidant effects by reducing ROS levels, increasing SOD activity and GSH levels, and lowering MDA levels. These effects were largely attributed to EV-miRNAs, which induce epigenetic modifications that modulate redox-related signaling pathways. However, the variability in EV isolation methods and characterization approaches highlights the need for standardization to improve data comparability. Despite their therapeutic potential, this significant heterogeneity in EV research remains a barrier to translation. Moreover, further exploration of epigenetic mechanisms is essential to fully harness their benefits for OS-related diseases.

The epigenetic landscape of mesenchymal stem cell and extracellular vesicle therapy

Mesenchymal stem cell (MSC) therapy shows great potential for treating tissue impairments and immune disorders. Epigenetic regulation is a core molecular signature that ensures long-lasting memory in MSC functional modulation and mediates therapeutic efficacy. Studies reveal that transplanted MSCs drive epigenetic changes in recipient cells, which contributes to restoration of organismal and microenvironmental homeostasis. Extracellular vesicles (EVs) derived from MSCs, including exosomes and apoptotic vesicles (apoVs), enable the transfer of epigenetic regulators, orchestrating intercellular epigenetic reprogramming and signaling modulation in both local and systemic microenvironments. Here, the epigenetic regulation of MSC and EV therapies is reviewed, together with current challenges, aiming to deepen the understanding of donor-recipient communication and inspire next-generation approaches to counteract tissue defects and diseases.

Mesenchymal stem cells and their derivatives as potential longevity-promoting tools

Mesenchymal stem cells (MSCs) and blood plasma/MSC-derived extracellular vesicles (EVs) offer promising tools to promote longevity and treat age-related diseases. MSCs have low immunogenicity and tumorigenicity, and their efficacy is relatively independent of the donor age in humans (but not in rodents). Systemic administration of MSCs and stem cell/blood-derived EVs modified the omic profiles of various organs of aged rodents towards the young ones. The application of EVs appears to be even more beneficial than MSCs. Remarkably, over 70% of microRNAs, which are over-presented in ESC-derived EVs, were found to target longevity-associated genes. Along with MSCs, other types of stem cells were reported to display health- and lifespan-extending effects. Pluripotent Muse cells, a specific subpopulation of MSCs, which possess a number of unique features, could be particularly relevant for promoting healthspan. The rejuvenation potential of MSCs, EVs, and Muse cells warrants further investigation in both animal models and clinical trials, using aging clocks for biological age determination as one of the endpoints.

Comparative Analysis of the Therapeutic Potential of Extracellular Vesicles Secreted by Aged and Young Bone Marrow-Derived Mesenchymal Stem Cells in Osteoarthritis Pathogenesis

Osteoarthritis (OA), a joint disease, burdens global healthcare due to aging and obesity. Recent studies show that extracellular vesicles (EVs) from bone marrow-derived mesenchymal stem cells (BMSCs) contribute to joint homeostasis and OA management. However, the impact of donor age on BMSC-derived EV efficacy remains underexplored. In this study, we investigated EV efficacy from young BMSCs (2-month-old) in mitigating OA, contrasting them with EVs from aged BMSCs (27-month-old). The study used destabilisation of the medial meniscus (DMM) surgery on mouse knee joints to induce accelerated OA. Cartilage degeneration markers and senescence markers' expression levels were investigated in response to EV treatment. The therapeutic impact of EVs on chondrocytes under inflammatory responses was also evaluated. Despite having similar morphologies, EVs from young BMSCs markedly decreased senescence and improved chondroprotection by activating the PTEN pathway while simultaneously suppressing the upregulation of the PI3K/AKT pathways, proving to be more effective than those from older BMSCs in vitro. Furthermore, intraperitoneal injections of EVs from young donors significantly mitigated OA progression by preserving cartilage and reducing synovitis in a surgical OA model using DMM in mice. These findings highlight that donor age as a critical determinant in the therapeutic potential of BMSC-derived EVs for clinical use in OA treatment.

Small extracellular vesicles from young adipose-derived stem cells ameliorate age-related changes in the heart of old mice

BACKGROUND

Aging entails a progressive decline in physiological functions, elevating the risk of age-related diseases like heart failure or aortic stenosis. Stem cell therapies, especially those that use paracrine signaling, can potentially mitigate the adverse effects of aging.

OBJECTIVES

The objective is to explore the potential of small extracellular vesicles (sEVs) derived from young adipose-derived stem cells (ADSC-sEVs) in reversing structural, molecular, and functional changes associated with aging in the heart.

METHODS

Aged C57BL/6J mice were treated intravenously with ADSC-sEVs from young mice or PBS as controls. Young mice were included to identify specific age-associated changes. The impact of sEV treatment on cardiac function was assessed using transthoracic echocardiography and physical endurance tests. Histological and molecular analyses were conducted on heart tissue to evaluate structural changes and markers of senescence, inflammation, and oxidative stress. A comprehensive metabolomic analysis was also performed on heart tissues to identify changes in metabolic profiles associated with aging and treatment status.

RESULTS

The administration of ADSC-sEVs significantly improves several aging-associated cardiac parameters, including oxidative stress, inflammation, and cellular senescence reductions. We also report on the age-related reversal of myocardial structure and function changes, highlighted by decreased fibrosis and improved vascularization. Notably, echocardiographic assessments reveal that sEV treatments ameliorate diastolic dysfunction and left ventricle structural alterations typically associated with aging. Furthermore, the treatment shifts the heart metabolome towards a more youthful profile.

CONCLUSIONS

These results denote the potential of ADSC-sEVs as a novel, noninvasive therapeutic strategy for mitigating cardiac aging-associated functional decline.

Antiageing strategy for neurodegenerative diseases: from mechanisms to clinical advances

In the context of global ageing, the prevalence of neurodegenerative diseases and dementia, such as Alzheimer's disease (AD), is increasing. However, the current symptomatic and disease-modifying therapies have achieved limited benefits for neurodegenerative diseases in clinical settings. Halting the progress of neurodegeneration and cognitive decline or even improving impaired cognition and function are the clinically meaningful goals of treatments for neurodegenerative diseases. Ageing is the primary risk factor for neurodegenerative diseases and their associated comorbidities, such as vascular pathologies, in elderly individuals. Thus, we aim to elucidate the role of ageing in neurodegenerative diseases from the perspective of a complex system, in which the brain is the core and peripheral organs and tissues form a holistic network to support brain functions. During ageing, the progressive deterioration of the structure and function of the entire body hampers its active and adaptive responses to various stimuli, thereby rendering individuals more vulnerable to neurodegenerative diseases. Consequently, we propose that the prevention and treatment of neurodegenerative diseases should be grounded in holistic antiageing and rejuvenation means complemented by interventions targeting disease-specific pathogenic events. This integrated approach is a promising strategy to effectively prevent, pause or slow down the progression of neurodegenerative diseases.

Advanced progress of adipose-derived stem cells-related biomaterials in maxillofacial regeneration

The tissue injury in maxillofacial region affects patients' physical function and specific mental health. This decade, utilizing regenerative medicine to achieve tissue regeneration has been proved a hopeful direction. Seed cells play a vital role in regeneration strategy. Among various kinds of stem cells that effectively to regenerate the soft and hard tissue of maxillofacial region, adipose-derived stem cells (ADSCs) have gained increasing interests of researchers due to their abundant sources, easy availability and multi-differentiation potentials in recent decades. Thus, this review focuses on the advances of ADSCs-based biomaterial in maxillofacial regeneration from the progress and strategies perspective. It is structured as introducing the properties of ADSCs, biomaterials (polymers, ceramics and metals) within ADSCs and the latest applications of ADSCs in maxillofacial regeneration, including temporomandibular joint (TMJ), bone, periodontal tissue, tooth, nerve as well as cosmetic field. In order to further facilitate ADSCs-based therapies as an emerging platform for regenerative medicine, this review also emphasized current challenges in translating ADSC-based therapies into clinical application and dissussed the strategies to solve these obstacles.

hESC-derived extracellular vesicles enriched with MFGE-8 and the GSH redox system act as senotherapeutics for neural stem cells in ischemic stroke

Human embryonic stem cells (hESCs) and their extracellular vesicles (EVs) hold significant potential for tissue repair and regeneration. Neural stem cells (NSCs) in the adult brain often acquire senescent phenotypes after ischemic injuries, releasing neurodegenerative senescence-associated secretory phenotype factors. In this study, we investigated the senotherapeutic effects of hESC-EVs on NSCs and confirmed their neuroprotective effects in neurons via rejuvenation of NSC secretions. Proteomic profiling of hESC-EVs identified MFGE-8 as a critical bridging molecule to NSCs. We also found that the glutathione (GSH) redox system is a key contributor to the therapeutic antioxidant activity of hESC-EVs. Additionally, EVs produced by the hypoxic preconditioning of hESCs (hESC-HypoxEVs) exhibited reinforced GSH redox capacity and further enhanced the senotherapeutic effects on NSCs compared to naïve hESC-EVs. We also demonstrated that administration of hESC-HypoxEVs, precoated with MFGE-8, significantly increased the populations of NSCs and newborn neurons in the subventricular zone of the brain and improved sensorimotor functions in a rat model of ischemic stroke. Our study suggests that combining hESC-HypoxEVs with MFGE-8 may serve as an effective therapeutic modality for reversing senescence and enhancing the neurogenic potential of NSCs to treat neurodegenerative diseases.

Stem cells from tooth apical papilla modulate fibromyalgia-like changes in mice

BACKGROUND

The treatment of fibromyalgia remains a current challenge. While the analgesic effects of mesenchymal stem cells have been the subject of previous research, their potential in managing fibromyalgia symptoms needs further investigation. In this study, we investigated the effects of human stem cells from tooth apical papilla (SCAP), when administered systemically, in a mouse model of fibromyalgia induced by reserpine.

METHODS

The effects of repeated intraperitoneal (i.p.) treatment with SCAP were evaluated in the mouse model of fibromyalgia induced by reserpine, by assessing behavioral and biochemical parameters.

RESULTS

The systemic treatment with SCAP significantly reduced the mechanical and thermal hypersensitivity induced by reserpine in mice. Moreover, the SCAP treatment also reversed depression-like behavior, as assessed in the forced swimming test (FST). The SCAP administration partly restored the reduction in the total number of entries in the elevated plus maze but failed to alter the fatigue intensity or the grip strength. The treatment with SCAP significantly increased dopamine, glutamate, and glutathione levels in the masseter muscle compared to the vehicle-treated control animals. Conversely, the SCAP administration decreased the glutathione levels in the prefrontal cortex and spinal cord compared to the control mice. Finally, the repeated treatment with SCAP led to a significant increase in the spinal cord levels of the chemokine CXCL1/KC.

CONCLUSIONS

Our research findings offer new insights into the efficacy of human SCAP in a pre-clinical model of fibromyalgia, likely through the modulation of both peripheral and central mechanisms.

Bifidobacterium adolescentis-derived nicotinic acid improves host skeletal muscle mitochondrial function to ameliorate sarcopenia

Sarcopenia significantly diminishes quality of life and increases mortality risk in older adults. While the connection between the gut microbiome and muscle health is recognized, the underlying mechanisms are poorly understood. In this study, shotgun metagenomics revealed that Bifidobacterium adolescentis is notably depleted in individuals with sarcopenia, correlating with reduced muscle mass and function. This finding was validated in aged mice. Metabolomics analysis identified nicotinic acid as a key metabolite produced by B. adolescentis, linked to improvements in muscle mass and functionality in individuals with sarcopenia. Mechanistically, nicotinic acid restores nicotinamide adenine dinucleotide (NAD+) levels in muscle, inhibits the FoxO3/Atrogin-1/Murf-1 axis, and promotes satellite cell proliferation, reducing muscle atrophy. Additionally, NAD+ activation enhances the silent-information-regulator 1 (SIRT1)/peroxisome-proliferator-activated-receptor-γ-coactivator 1-alpha (PGC-1α) axis, stimulating mitochondrial biogenesis and promoting oxidative metabolism in slow-twitch fibers, ultimately improving muscle function. Our findings suggest that B. adolescentis-derived nicotinic acid could be a promising therapeutic strategy for individuals with sarcopenia.

Intercellular communication is crucial in the regulation of healthy aging via exosomes

The hallmarks of aging encompass a variety of molecular categories (genomic, telomeric, and epigenetic), organelles (proteostasis, autophagy, and mitochondria), cellular components (including stem cells), systems (such as intercellular communication and chronic inflammation), and environmental factors (dysbiosis and nutrient sensing). These hallmarks play a crucial role in the aging process. Despite their intricate interconnections, the relationships among the hallmarks of aging remain unclear. Although the boundaries between these hallmarks may be indistinct, they exhibit interdependence, with the influence of one hallmark extending to others. Building on this foundation, we investigated the interrelations among the various hallmarks of aging and provided a systematic overview of their logical relationships, proposing that cellular communication plays a crucial role in the aging process. Exosomes function as a primary mode of cellular communication and significantly impact the aging process. Therefore, we propose utilizing exosomes as valuable tools for understanding the mechanisms of aging and addressing age-related concerns. Exosomes may represent a novel approach for the treatment and diagnosis of aging-related conditions in animals. Furthermore, our research reveals that exocytosis in young nematodes slows the aging process, while exocytosis in aged nematodes has the opposite effect, accelerating aging. In conclusion, exosomes act as intercellular messengers that influence the maintenance of a healthy aging process and link the hallmarks of aging with indicators of well-being.

The immunosenescence clock: A new method for evaluating biological age and predicting mortality risk

Precisely assessing an individual's immune age is critical for developing targeted aging interventions. Although traditional methods for evaluating biological age, such as the use of cellular senescence markers and physiological indicators, have been widely applied, these methods inherently struggle to capture the full complexity of biological aging. We propose the concept of an 'immunosenescence clock' that evaluates immune system changes on the basis of changes in immune cell abundance and omics data (including transcriptome and proteome data), providing a complementary indicator for understanding age-related physiological transformations. Rather than claiming to definitively measure biological age, this approach can be divided into a biological age prediction clock and a mortality prediction clock. The main function of the biological age prediction clock is to reflect the physiological state through the transcriptome data of peripheral blood mononuclear cells (PBMCs), whereas the mortality prediction clock emphasizes the ability to identify people at high risk of mortality and disease. We hereby present nearly all of the immunosenescence clocks developed to date, as well as their functional differences. Critically, we explicitly acknowledge that no single diagnostic test can exhaustively capture the intricate changes associated with biological aging. Furthermore, as these biological functions are based on the acceleration or delay of immunosenescence, we also summarize the factors that accelerate immunosenescence and the methods for delaying it. A deep understanding of the regulatory mechanisms of immunosenescence can help establish more accurate immune-age models, providing support for personalized longevity interventions and improving quality of life in old age.

Immune evasion through mitochondrial transfer in the tumour microenvironment

Cancer cells in the tumour microenvironment use various mechanisms to evade the immune system, particularly T cell attack1. For example, metabolic reprogramming in the tumour microenvironment and mitochondrial dysfunction in tumour-infiltrating lymphocytes (TILs) impair antitumour immune responses2-4. However, detailed mechanisms of such processes remain unclear. Here we analyse clinical specimens and identify mitochondrial DNA (mtDNA) mutations in TILs that are shared with cancer cells. Moreover, mitochondria with mtDNA mutations from cancer cells are able to transfer to TILs. Typically, mitochondria in TILs readily undergo mitophagy through reactive oxygen species. However, mitochondria transferred from cancer cells do not undergo mitophagy, which we find is due to mitophagy-inhibitory molecules. These molecules attach to mitochondria and together are transferred to TILs, which results in homoplasmic replacement. T cells that acquire mtDNA mutations from cancer cells exhibit metabolic abnormalities and senescence, with defects in effector functions and memory formation. This in turn leads to impaired antitumour immunity both in vitro and in vivo. Accordingly, the presence of an mtDNA mutation in tumour tissue is a poor prognostic factor for immune checkpoint inhibitors in patients with melanoma or non-small-cell lung cancer. These findings reveal a previously unknown mechanism of cancer immune evasion through mitochondrial transfer and can contribute to the development of future cancer immunotherapies.

Impact of Chinese visceral adiposity index on all-cause mortality risk in community-dwelling older adults: a prospective cohort study

BACKGROUNDS

Whether excess visceral fat tissue increases the risk of death in older individuals remains controversial.

AIMS

To investigate the association between the Chinese Visceral Adiposity Index (CVAI) and all-cause mortality risk in older Chinese individuals.

METHODS

This cohort study utilized data of individuals aged ≥ 65 years in 2014 to 2018 wave from the Chinese Longitudinal Healthy Longevity Survey database. Older individuals in the 2014 wave were included and followed up in 2018. CVAI was calculated based on age, body size, and blood lipid parameters, with higher values indicating increased visceral fat. Survival status was determined from official death certificates, local primary healthcare providers, or the family members of participants. Kaplan-Meier survival curve and log-rank test were employed to analyze cumulative mortality risk through CVAI tertiles (tertile 1: CVAI index < 97.34; tertile 2: 97.43 ≤ CVAI index < 132.21; and tertile 3: CVAI index ≥ 132.21). A Cox proportional hazards regression model was used to assess the relationship between the CVAI groups and all-cause mortality risk. Additionally, a sensitivity analysis was performed by excluding participants who died within the first year of follow-up. A subgroup analysis was performed based on age and sex, and a restricted cubic spline plot was created to analyze the dose-response relationship between CVAI and mortality risk.

RESULTS

A total of 1414 individuals were included, and the mean age of the participants was 84.6 (standard deviation: 10.9) years, of which 46.4% were women and 32.8% were died during a median follow-up time of 36.4 months. In the multivariable adjusted Cox regression model, we observed a significantly lower risk of mortality in the CVAI tertile 2 and 3 groups than in the tertile 1 group. The hazard ratios (HR) of the tertile 2 and 3 groups were 0.68 (95% CI, approximately 0.52-0.89) and 0.63 (95% CI, approximately 0.48-0.82), respectively. Subgroup analysis revealed that the protective effect of higher CVAI levels on mortality was more pronounced in participants aged 65-79 years and in women.

CONCLUSION

Our study established a linear relationship between CVAI and mortality risk among community-dwelling older adults, with higher CVAI levels associated with a lower risk of all-cause mortality. These findings highlight the potential importance of visceral adiposity in predicting mortality risk in community-dwelling older adults.

Dopamine-conjugated extracellular vesicles induce autophagy in Parkinson's disease

The application of extracellular vesicles (EVs) as vehicles for anti-Parkinson's agents represents a significant advance, yet their clinical translation is hampered by challenges in efficient brain delivery and complex blood-brain barrier (BBB) targeting strategies. In this study, we engineered dopamine onto the surface of adipose-derived stem cell EVs (Dopa-EVs) utilizing a facile, two-step cross-linking approach. This engineering enhanced neuronal uptake of the EVs in primary neurons and neuroblastoma cells, a process shown to be competitively inhibited by dopamine pretreatment and dopamine receptor antibodies. Notably, Dopa-EVs demonstrated increased brain accumulation in mouse Parkinson's disease (PD) models. Therapeutically, Dopa-EVs administration led to the rescue of dopaminergic neuronal loss and amelioration of behavioural deficits in both 6-hydroxydopamine (6-OHDA) and α-Syn PFF-induced PD models. Furthermore, we observed that Dopa-EVs stimulated autophagy evidenced by the upregulation of Beclin-1 and LC3-II. These findings collectively indicate that surface modification of EVs with dopamine presents a potent strategy for targeting dopaminergic neurons in the brain. The remarkable therapeutic potential of Dopa-EVs, demonstrated in PD models, positions them as a highly promising candidate for PD treatment, offering a significant advance over current therapeutic modalities.

Climbing the longevity pyramid: overview of evidence-driven healthcare prevention strategies for human longevity

Longevity medicine is an emerging and iterative healthcare discipline focusing on early detection, preventive measures, and personalized approaches that aim to extend healthy lifespan and promote healthy aging. This comprehensive review introduces the innovative concept of the "Longevity Pyramid." This conceptual framework delineates progressive intervention levels, providing a structured approach to understanding the diverse strategies available in longevity medicine. At the base of the Longevity Pyramid lies the level of prevention, emphasizing early detection strategies and advanced diagnostics or timely identification of potential health issues. Moving upwards, the next step involves lifestyle modifications, health-promoting behaviors, and proactive measures to delay the onset of age-related conditions. The Longevity Pyramid further explores the vast range of personalized interventions, highlighting the importance of tailoring medical approaches based on genetic predispositions, lifestyle factors, and unique health profiles, thereby optimizing interventions for maximal efficacy. These interventions aim to extend lifespan and reduce the impact and severity of age-related conditions, ensuring that additional years are characterized by vitality and wellbeing. By outlining these progressive levels of intervention, this review offers valuable insights into the evolving field of longevity medicine. This structured framework guides researchers and practitioners toward a nuanced strategic approach to advancing the science and practice of healthy aging.

Engineering ADSCs by manipulating YAP for lymphedema treatment in a mouse tail model

Secondary lymphedema is a chronic disease associated with deformity of limbs and dysfunction; however, conventional therapies are not curative. Adipose-derived stem cells (ADSCs) based therapy is a promising way, but a single transplantation of ADSCs has limited efficacy. In this study, ADSCs were engineered in vitro and then transplanted into the site of lymphedema. Yes-associated protein (YAP), a crucial regulator of Hippo pathway, plays an important role in regulating stem cell functions. We examined the YAP expression in a mouse tail lymphedema model, and found that transplanted ADSCs exhibited high expression level of YAP and a large number of YAP positive cells existed in lymphedema environment. In vitro, the downregulation of YAP in ADSCs resulted in higher expression levels of genes related to lymphangiogenesis such as Lyve-1, VEGFR-3 and Prox-1. In vivo, YAP-engineered ADSCs generated abundant VEGFR-3-positive lymphatic vessels and significantly improved subcutaneous fibrosis. These results indicated that the transplantation of pre-engineered ADSCs by manipulating YAP is a promising strategy for lymphatic reconstruction.

Nose-to-brain delivery of stem cells in stroke: the role of extracellular vesicles

Stem cell transplantation offers a promising therapy that can be administered days, weeks, or months after a stroke. We recognize 2 major mitigating factors that remain unresolved in cell therapy for stroke, notably: (1) well-defined donor stem cells and (2) mechanism of action. To this end, we advance the use of ProtheraCytes, a population of non-adherent CD34+ cells derived from human peripheral blood and umbilical cord blood, which have been processed under good manufacturing practice, with testing completed in a phase 2 clinical trial in post-acute myocardial infarction (NCT02669810). We also reveal a novel mechanism whereby ProtheraCytes secrete growth factors and extracellular vesicles (EVs) that are associated with angiogenesis and vasculogenesis. Our recent data revealed that intranasal transplantation of ProtheraCytes at 3 days after experimentally induced stroke in adult rats reduced stroke-induced behavioral deficits and histological damage up to 28 days post-stroke. Moreover, we detected upregulation of human CD63+ EVs in the ischemic brains of stroke animals that were transplanted with ProtheraCytes, which correlated with increased levels of DCX-labeled neurogenesis and VEGFR1-associated angiogenesis and vasculogenesis, as well as reduced Iba1-marked inflammation. Altogether, these findings overcome key laboratory-to-clinic translational hurdles, namely the identification of well-characterized, clinical grade ProtheraCytes and the elucidation of a potential CD63+ EV-mediated regenerative mechanism of action. We envision that additional translational studies will guide the development of clinical trials for intranasal ProtheraCytes allografts in stroke patients, with CD63 serving as a critical biomarker.

Canine mesenchymal stem cell-derived exosomes attenuate renal ischemia-reperfusion injury through miR-146a-regulated macrophage polarization

Introduction

The most common factor leading to renal failure or death is renal IR (ischemia-reperfusion). Studies have shown that mesenchymal stem cells (MSCs) and their exosomes have potential therapeutic effects for IR injury by inhibiting M1 macrophage polarization and inflammation. In this study, the protective effect and anti-inflammatory mechanism of adipose-derived mesenchymal stem cell-derived exosomes (ADMSC-Exos) after renal IR were investigated.

Method

Initially, ADMSC-Exos were intravenously injected into IR experimental beagles, and the subsequent assessment focused on inflammatory damage and macrophage phenotype. Furthermore, an in vitro inflammatory model was established by inducing DH82 cells with LPS. The impact on inflammation and macrophage phenotype was then evaluated using ADMSC and regulatory miR-146a.

Results

Following the administration of ADMSC-Exos in IR canines, a shift from M1 to M2 macrophage polarization was observed. Similarly, in vitro experiments demonstrated that ADMSC-Exos enhanced the transformation of LPS-induced macrophages from M1 to M2 type. Notably, the promotion of macrophage polarization by ADMSC-Exos was found to be attenuated upon the inhibition of miR-146a in ADMSC-Exos.

Conclusion

These findings suggest that miR-146a plays a significant role in facilitating the transition of LPS-induced macrophages from M1 to M2 phenotype. As a result, the modulation of macrophage polarization by ADMSC-Exos is achieved via the encapsulation and conveyance of miR-146a, leading to diminished infiltration of inflammatory cells in renal tissue and mitigation of the inflammatory reaction following canine renal IR.

Extracellular Vesicle-Contained Thrombospondin 1 Retards Age-Related Degenerative Tendinopathy by Rejuvenating Tendon Stem/Progenitor Cell Senescence

Advanced age is a major risk factor for age-related degenerative tendinopathy. During aging, tendon stem/progenitor cell (TSPC) function declines owing to the transition from a normal quiescent state to a senescent state. Extracellular vesicles (EVs) from young stem cells are reported to possess anti-aging functions. However, it remains unclear whether EVs from young TSPCs (TSPC-EVs) can rejuvenate senescent TSPCs to delay age-related degeneration. Here, this study finds that TSPC-EVs can mitigate the aging phenotypes of senescent TSPCs and maintain their tenogenic capacity. In vitro studies reveal that TSPC-EVs can reinstall autophagy in senescent TSPCs to alleviate cellular senescence, and that the re-establishment of autophagy is mediated by the PI3K/AKT pathway. Mechanistically, this study finds that thrombospondin 1, a negative regulator of the PI3K/AKT pathway, is enriched in TSPC-EVs and can be transported to senescent TSPCs. Moreover, in vivo studies show that the local delivery of TSPC-EVs can rejuvenate senescent TSPCs and promote their tenogenic differentiation, thereby rescuing tendon regeneration in aged rats. Taken together, TSPC-EVs as a novel cell-free approach have promising therapeutic potential for aging-related degenerative tendinopathy.

Contents of exosomes derived from adipose tissue and their regulation on inflammation, tumors, and diabetes

Adipose tissue (AT) serves as an energy-capacitive organ and performs functions involving paracrine- and endocrine-mediated regulation via extracellular vesicles (EVs) secretion. Exosomes, a subtype of EVs, contain various bioactive molecules with regulatory effects, such as nucleic acids, proteins, and lipids. AT-derived exosomes (AT-exos) include exosomes derived from various cells in AT, including adipocytes, adipose-derived stem cells (ADSCs), macrophages, and endothelial cells. This review aimed to comprehensively evaluate the impacts of different AT-exos on the regulation of physiological and pathological processes. The contents and functions of adipocyte-derived exosomes and ADSC-derived exosomes are compared simultaneously, highlighting their similarities and differences. The contents of AT-exos have been shown to exert complex regulatory effects on local inflammation, tumor dynamics, and insulin resistance. Significantly, differences in the cargoes of AT-exos have been observed among diabetes patients, obese individuals, and healthy individuals. These differences could be used to predict the development of diabetes mellitus and as therapeutic targets for improving insulin sensitivity and glucose tolerance. However, further research is needed to elucidate the underlying mechanisms and potential applications of AT-exos.

Synergistic delivery of hADSC-Exos and antioxidants has inhibitory effects on UVB-induced skin photoaging

Ultraviolet B (UVB) light exposure accelerates skin photoaging. Human adipose-derived stem cell exosomes (hADSC-Exos) and some antioxidants may have anti-photoaging effects. However, it is unknown whether the combination of hADSC-Exos and antioxidants plays a synergistic role in anti-photoaging. In cellular and 3D skin models, we showed that vitamin E (VE) and hADSC-Exos were optimal anti-photoaging combinations. In vivo, VE and hADSC-Exos increased skin tightening and elasticity in UVB-induced photoaging mice Combined treatment with VE and hADSC-Exos inhibited SIRT1/NF-κB pathway. These findings contribute to the understanding of hADSC-Exos in conjunction with other antioxidants, thereby providing valuable insights for the future pharmaceutical and cosmetic industries.

Regulatory Effects of Senescent Mesenchymal Stem Cells: Endotheliocyte Reaction

Currently, there is a growing focus on aging and age-related diseases. The processes of aging are based on cell senescence, which results in changes in intercellular communications and pathological alterations in tissues. In the present study, we investigate the influence of senescent mesenchymal stem cells (MSCs) on endothelial cells (ECs). In order to induce senescence in MSCs, we employed a method of stress-induced senescence utilizing mitomycin C (MmC). Subsequent experiments involved the interaction of ECs with MSCs in a coculture or the treatment of ECs with the secretome of senescent MSCs. After 48 h, we assessed the EC state. Our findings revealed that direct interaction led to a decrease in EC proliferation and migratory activity of the coculture. Furthermore, there was an increase in the activity of the lysosomal compartment, as well as an upregulation of the genes P21, IL6, IL8, ITGA1, and ITGB1. Treatment of ECs with the "senescent" secretome resulted in less pronounced effects, although a decrease in proliferation and an increase in ICAM-1 expression were observed. The maintenance of high levels of typical "senescent" cytokines and growth factors after 48 h suggests that the addition of the "senescent" secretome may have a prolonged effect on the cells. It is noteworthy that in samples treated with the "senescent" secretome, the level of PDGF-AA was higher, which may explain some of the pro-regenerative effects of senescent cells. Therefore, the detected changes may underlie both the negative and positive effects of senescence. The findings provide insight into the effects of cell senescence in vitro, where many of the organism's regulatory mechanisms are absent.

Stem cell-derived extracellular vesicles as senotherapeutics

Cellular senescence (CS) is recognized as one of the hallmarks of aging, and an important player in a variety of age-related pathologies. Accumulation of senescent cells can promote a pro-inflammatory and pro-cancerogenic microenvironment. Among potential senotherapeutics are extracellular vesicles (EVs) (40-1000 nm), including exosomes (40-150 nm), that play an important role in cell-cell communications. Here, we review the most recent studies on the impact of EVs derived from stem cells (MSCs, ESCs, iPSCs) as well as non-stem cells of various types on CS and discuss potential mechanisms responsible for the senotherapeutic effects of EVs. The analysis revealed that (i) EVs derived from stem cells, pluripotent (ESCs, iPSCs) or multipotent (MSCs of various origin), can mitigate the cellular senescence phenotype both in vitro and in vivo; (ii) this effect is presumably senomorphic; (iii) EVs display cross-species activity, without apparent immunogenic responses. In summary, stem cell-derived EVs appear to be promising senotherapeutics, with a feasible application in humans.

Extracellular MicroRNAs as Potential Biomarkers for Frail Kidney Phenotype: Progresses and Precautions

Frailty describes the cumulative subtle health deficits leading to an increased vulnerability to insults among older individuals or disease-laden ones. The prevalence of frailty increases substantially and relentlessly over declining renal function. Frailty in patients with chronic kidney disease (CKD) carries kidney-specific risk factors, clinical correlates and outcomes associations, hence alternatively termed frail kidney phenotype by researchers. Pathogenetically, miRNAs participate extensively in the development and aggravation of frailty, including the occurrence of frail kidney phenotype in CKD patients. These understandings spark profound interest in discovering biomarkers for identifying this detrimental phenotype, and extracellular miRNAs emerge as potentially useful ones. Pilot studies identify promising miRNA candidates for evaluating intermediates and surrogates of frail kidney phenotype, and more are underway. Several potential miRNA species in biologic fluids, such as circulating miR-29b and miR-223 (as inflammatory markers), exosomal miR-16-5p, miR-17/92 cluster members, and miR-106-5p (for uremic vasculopathy), serum exosomal miR-203a-3p (for uremic sarcopenia) have been examined and can be promising choices. Nonetheless, there remains research gap in affirming the direct connections between specific miRNAs and frail kidney phenotype. This stems partially from multiple limitations less well acknowledged before. From this perspective, we further outline the limitations and precautions prior to validating specific extracellular miRNA(s) for this purpose, from the definition of frailty definition, the functional and tissue specificity of miRNAs, the severity of CKD, and various technical considerations. It is expected that more affirmative studies can be produced for extending the utility of extracellular miRNAs in predicting frail kidney phenotype.

Frailty and biological age. Which best describes our aging and longevity?

Frailty and Biological Age are two closely related concepts; however, frailty is a multisystem geriatric syndrome that applies to elderly subjects, whereas biological age is a gerontologic way to describe the rate of aging of each individual, which can be used from the beginning of the aging process, in adulthood. If frailty reaches less consensus on the definition, it is a term much more widely used than this of biological age, which shows a clearer definition but is scarcely employed in social and medical fields. In this review, we suggest that this Biological Age is the best to describe how we are aging and determine our longevity, and several examples support our proposal.

Stem cell secretome treatment improves whole-body metabolism, reduces adiposity, and promotes skeletal muscle function in aged mice

Aging coincides with the progressive loss of muscle mass and strength, increased adiposity, and diminished physical function. Accordingly, interventions aimed at improving muscle, metabolic, and/or physical health are of interest to mitigate the adverse effects of aging. In this study, we tested a stem cell secretome product, which contains extracellular vesicles and growth, cytoskeletal remodeling, and immunomodulatory factors. We examined the effects of 4 weeks of 2×/week unilateral intramuscular secretome injections (quadriceps) in ambulatory aged male C57BL/6 mice (22-24 months) compared to saline-injected aged-matched controls. Secretome delivery substantially increased whole-body lean mass and decreased fat mass, corresponding to higher myofiber cross-sectional area and smaller adipocyte size, respectively. Secretome-treated mice also had greater whole-body physical function (grip strength and rotarod performance) and had higher energy expenditure and physical activity levels compared to control mice. Furthermore, secretome-treated mice had greater skeletal muscle Pax7+ cell abundance, capillary density, collagen IV turnover, reduced intramuscular lipids, and greater Akt and hormone sensitive lipase phosphorylation in adipose tissue. Finally, secretome treatment in vitro directly enhanced muscle cell growth and IL-6 production, and in adipocytes, it reduced lipid content and improved insulin sensitivity. Moreover, indirect treatment with secretome-treated myotube culture media also enhanced muscle cell growth and adipocyte size reduction. Together, these data suggest that intramuscular treatment with a stem cell secretome improves whole-body metabolism, physical function, and remodels skeletal muscle and adipose tissue in aged mice.

Proximity hybridization based "turn-on" DNA tweezers for accurate and enzyme-free small extracellular vesicle analysis

Small extracellular vesicles (sEVs) are a type of extracellular vesicle that carries many types of molecular information. The identification of sEVs is essential for the non-invasive detection and treatment of illnesses. Hence, there is a significant need for the development of simple, sensitive, and precise methods for sEV detection. Herein, a DNA tweezers-based assay utilizing a "turn-on" mechanism and proximity ligation was suggested for the efficient and rapid detection of sEVs through amplified fluorescence. The target facilitates the proximity combination of the C1 probe and C2 probe, resulting in the formation of a complete extended sequence. The elongated sequence can cyclically initiate the hairpin probe (HP), leading to the activation of DNA tweezers. An excellent linear correlation was achieved, with a limit of detection of 57 particles per μL. Furthermore, it has been effectively employed to analyze sEVs under intricate experimental conditions, demonstrating a promising and pragmatic prospect for future applications. Given that the identification of sEVs was successfully accomplished using a single-step method that exhibited exceptional sensitivity and strong resistance to interference, the proposed technique has the potential to provide a beneficial platform for accurate recognition of sEVs and early detection of diseases.

Energy metabolism as therapeutic target for aged wound repair by engineered extracellular vesicle

Aging skin, vulnerable to age-related defects, is poor in wound repair. Metabolic regulation in accumulated senescent cells (SnCs) with aging is essential for tissue homeostasis, and adequate ATP is important in cell activation for aged tissue repair. Strategies for ATP metabolism intervention hold prospects for therapeutic advances. Here, we found energy metabolic changes in aging skin from patients and mice. Our data show that metformin engineered EV (Met-EV) can enhance aged mouse skin repair, as well as ameliorate cellular senescence and restore cell dysfunctions. Notably, ATP metabolism was remodeled as reduced glycolysis and enhanced OXPHOS after Met-EV treatment. We show Met-EV rescue senescence-induced mitochondria dysfunctions and mitophagy suppressions, indicating the role of Met-EV in remodeling mitochondrial functions via mitophagy for adequate ATP production in aged tissue repair. Our results reveal the mechanism for SnCs rejuvenation by EV and suggest the disturbed energy metabolism, essential in age-related defects, to be a potential therapeutic target for facilitating aged tissue repair.

Fecal Microbiota Transplantation Attenuates Frailty via Gut-Muscle Axis in Old Mice

Targeting adverse pathogenic gut microbiota regulation through fecal microbiota transplantation (FMT) may restore health and has been validated in some aging-related diseases. However, the mechanisms of the gut microbiota's role in frailty and whether modulation of the gut microbiota can treat age-related frailty remain largely unknown. To assess the effects of FMT on frailty, we used bidirectional fecal microbiota transplantation in young and old mice. We demonstrated that fecal bacteria transplanted from old mice into young mice reduced body weight and grip strength (p=0.002), and led to elevated inflammatory factors in young mice, but had no significant effect on intestinal barrier function. Notably, FMT treatment in older mice not only improved frailty (grip strength: p=0.036, low physical activity: p=0.020, running speed: p=0.048, running time: p=0.058, frailty score: p=0.027) and muscle mass, but also improved intestinal ecological imbalances, intestinal barrier function, and systemic inflammation (serum TNF-α: p=0.002, and IL-6: p<0.001). KEGG enrichment analysis of fecal metabolites showed that FMT may ameliorate frailty through the sphingolipid metabolism pathway. In addition, aged mice given FMT treatment showed a significant increase in the abundance of SCFA-producing bacteria and increased levels of short-chain fatty acids (butyric acid: p=0.084, propionic acid: p=0.028). Subsequent further verification found that FMT ameliorating frailty may be achieved through SCFAs metabolism. Another mechanism study found that FMT reduces lipopolysaccharide levels (p<0.001), thereby inhibiting the TLR4/NF-κB signaling pathway and its downstream pro-inflammatory products. Therefore, regulating SCFAs metabolism by altering gut microbial composition and targeting the gut-muscle axis with LPS/TLR4 pathways may be potential strategies to treat frailty in older adults.

Extracellular vesicles from human urine-derived stem cells delay aging through the transfer of PLAU and TIMP1

Aging increases the risks of various diseases and the vulnerability to death. Cellular senescence is a hallmark of aging that contributes greatly to aging and aging-related diseases. This study demonstrates that extracellular vesicles from human urine-derived stem cells (USC-EVs) efficiently inhibit cellular senescence in vitro and in vivo. The intravenous injection of USC-EVs improves cognitive function, increases physical fitness and bone quality, and alleviates aging-related structural changes in different organs of senescence-accelerated mice and natural aging mice. The anti-aging effects of USC-EVs are not obviously affected by the USC donors' ages, genders, or health status. Proteomic analysis reveals that USC-EVs are enriched with plasminogen activator urokinase (PLAU) and tissue inhibitor of metalloproteinases 1 (TIMP1). These two proteins contribute importantly to the anti-senescent effects of USC-EVs associated with the inhibition of matrix metalloproteinases, cyclin-dependent kinase inhibitor 2A (P16INK4a), and cyclin-dependent kinase inhibitor 1A (P21cip1). These findings suggest a great potential of autologous USC-EVs as a promising anti-aging agent by transferring PLAU and TIMP1 proteins.

Exosomes: a promising avenue for cancer diagnosis beyond treatment

Exosomes, extracellular vesicles secreted by cells, have garnered significant attention in recent years for their remarkable therapeutic potential. These nanoscale carriers can be harnessed for the targeted delivery of therapeutic agents, such as pharmaceuticals, proteins, and nucleic acids, across biological barriers. This versatile attribute of exosomes is a promising modality for precision medicine applications, notably in the realm of cancer therapy. However, despite their substantial therapeutic potential, exosomes still confront challenges tied to standardization and scalability that impede their practice in clinical applications. Moreover, heterogeneity in isolation methodologies and limited cargo loading mechanisms pose obstacles to ensuring consistent outcomes, thereby constraining their therapeutic utility. In contrast, exosomes exhibit a distinct advantage in cancer diagnosis, as they harbor specific signatures reflective of the tumor's genetic and proteomic profile. This characteristic endows them with the potential to serve as valuable liquid biopsies for non-invasive and real-time monitoring, making possible early cancer detection for the development of personalized treatment strategies. In this review, we provide an extensive evaluation of the advancements in exosome research, critically examining their advantages and limitations in the context of cancer therapy and early diagnosis. Furthermore, we present a curated overview of the most recent technological innovations utilizing exosomes, with a focus on enhancing the efficacy of early cancer detection.

Extracellular vesicles for developing targeted hearing loss therapy

Substantial efforts have been made for local administration of small molecules or biologics in treating hearing loss diseases caused by either trauma, genetic mutations, or drug ototoxicity. Recently, extracellular vesicles (EVs) naturally secreted from cells have drawn increasing attention on attenuating hearing impairment from both preclinical studies and clinical studies. Highly emerging field utilizing diverse bioengineering technologies for developing EVs as the bioderived therapeutic materials, along with artificial intelligence (AI)-based targeting toolkits, shed the light on the unique properties of EVs specific to inner ear delivery. This review will illuminate such exciting research field from fundamentals of hearing protective functions of EVs to biotechnology advancement and potential clinical translation of functionalized EVs. Specifically, the advancements in assessing targeting ligands using AI algorithms are systematically discussed. The overall translational potential of EVs is reviewed in the context of auditory sensing system for developing next generation gene therapy.

Emerging epigenetic insights into aging mechanisms and interventions

Epigenetic dysregulation emerges as a critical hallmark and driving force of aging. Although still an evolving field with much to explore, it has rapidly gained significance by providing valuable insights into the mechanisms of aging and potential therapeutic opportunities for age-related diseases. Recent years have witnessed remarkable strides in our understanding of the epigenetic landscape of aging, encompassing pivotal elements, such as DNA methylation, histone modifications, RNA modifications, and noncoding (nc) RNAs. Here, we review the latest discoveries that shed light on new epigenetic mechanisms and critical targets for predicting and intervening in aging and related disorders. Furthermore, we explore burgeoning interventions and exemplary clinical trials explicitly designed to foster healthy aging, while contemplating the potential ramifications of epigenetic influences.

Extracellular vesicles set the stage for brain plasticity and recovery by multimodal signalling

Extracellular vesicles (EVs) are extremely versatile naturally occurring membrane particles that convey complex signals between cells. EVs of different cellular sources are capable of inducing striking therapeutic responses in neurological disease models. Differently from pharmacological compounds that act by modulating defined signalling pathways, EV-based therapeutics possess multiple abilities via a variety of effectors, thus allowing the modulation of complex disease processes that may have very potent effects on brain tissue recovery. When applied in vivo in experimental models of neurological diseases, EV-based therapeutics have revealed remarkable effects on immune responses, cell metabolism and neuronal plasticity. This multimodal modulation of neuroimmune networks by EVs profoundly influences disease processes in a highly synergistic and context-dependent way. Ultimately, the EV-mediated restoration of cellular functions helps to set the stage for neurological recovery. With this review we first outline the current understanding of the mechanisms of action of EVs, describing how EVs released from various cellular sources identify their cellular targets and convey signals to recipient cells. Then, mechanisms of action applicable to key neurological conditions such as stroke, multiple sclerosis and neurodegenerative diseases are presented. Pathways that deserve attention in specific disease contexts are discussed. We subsequently showcase considerations about EV biodistribution and delineate genetic engineering strategies aiming at enhancing brain uptake and signalling. By sketching a broad view of EV-orchestrated brain plasticity and recovery, we finally define possible future clinical EV applications and propose necessary information to be provided ahead of clinical trials. Our goal is to provide a steppingstone that can be used to critically discuss EVs as next generation therapeutics for brain diseases.

Stress, epigenetics, and aging: Unraveling the intricate crosstalk

Aging, as a complex process involving multiple cellular and molecular pathways, is known to be exacerbated by various stresses. Because responses to these stresses, such as oxidative stress and genotoxic stress, are known to interplay with the epigenome and thereby contribute to the development of age-related diseases, investigations into how such epigenetic mechanisms alter gene expression and maintenance of cellular homeostasis is an active research area. In this review, we highlight recent studies investigating the intricate relationship between stress and aging, including its underlying epigenetic basis; describe different types of stresses that originate from both internal and external stimuli; and discuss potential interventions aimed at alleviating stress and restoring epigenetic patterns to combat aging or age-related diseases. Additionally, we address the challenges currently limiting advancement in this burgeoning field.

Human Umbilical Cord Mesenchymal Stem Cell-Derived Exosomes Rescue Testicular Aging

BACKGROUND

Testicular aging is associated with diminished fertility and certain age-related ailments, and effective therapeutic interventions remain elusive. Here, we probed the therapeutic efficacy of exosomes derived from human umbilical cord mesenchymal stem cells (hUMSC-Exos) in counteracting testicular aging.

METHODS

We employed a model of 22-month-old mice and administered intratesticular injections of hUMSC-Exos. Comprehensive analyses encompassing immunohistological, transcriptomic, and physiological assessments were conducted to evaluate the effects on testicular aging. Concurrently, we monitored alterations in macrophage polarization and the oxidative stress landscape within the testes. Finally, we performed bioinformatic analysis for miRNAs in hUMSC-Exos.

RESULTS

Our data reveal that hUMSC-Exos administration leads to a marked reduction in aging-associated markers and cellular apoptosis while promoting cellular proliferation in aged testis. Importantly, hUMSC-Exos facilitated the restoration of spermatogenesis and elevated testosterone synthesis in aged mice. Furthermore, hUMSC-Exos could attenuate inflammation by driving the phenotypic shift of macrophages from M1 to M2 and suppress oxidative stress by reduced ROS production. Mechanistically, these efficacies against testicular aging may be mediated by hUMSC-Exos miRNAs.

CONCLUSIONS

Our findings suggest that hUMSC-Exos therapy presents a viable strategy to ameliorate testicular aging, underscoring its potential therapeutic significance in managing testicular aging.

The Role of Mesenchymal Stem/Stromal Cells Secretome in Macrophage Polarization: Perspectives on Treating Inflammatory Diseases

Mesenchymal stem/stromal cells (MSCs) have exhibited potential for treating multiple inflammation- related diseases (IRDs) due to their easy acquisition, unique immunomodulatory and tissue repair properties, and immune-privileged characteristics. It is worth mentioning that MSCs release a wide array of soluble bioactive components in the secretome that modulate host innate and adaptive immune responses and promote the resolution of inflammation. As the first line of defense, macrophages exist throughout the entire inflammation process. They continuously switch their molecular phenotypes accompanied by complementary functional regulation ranging from classically activated pro-inflammatory M1-type (M1) to alternatively activated anti-inflammatory M2-type macrophages (M2). Recent studies have shown that the active intercommunication between MSCs and macrophages is indispensable for the immunomodulatory and regenerative behavior of MSCs in pharmacological cell therapy products. In this review, we systematically summarized the emerging capacities and detailed the molecular mechanisms of the MSC-derived secretome (MSC-SE) in immunomodulating macrophage polarization and preventing excessive inflammation, providing novel insights into the clinical applications of MSC-based therapy in IRD management.

Macroporous Granular Hydrogels Functionalized with Aligned Architecture and Small Extracellular Vesicles Stimulate Osteoporotic Tendon-To-Bone Healing

Osteoporotic tendon-to-bone healing (TBH) after rotator cuff repair (RCR) is a significant orthopedic challenge. Considering the aligned architecture of the tendon, inflammatory microenvironment at the injury site, and the need for endogenous cell/tissue infiltration, there is an imminent need for an ideal scaffold to promote TBH that has aligned architecture, ability to modulate inflammation, and macroporous structure. Herein, a novel macroporous hydrogel comprising sodium alginate/hyaluronic acid/small extracellular vesicles from adipose-derived stem cells (sEVs) (MHA-sEVs) with aligned architecture and immunomodulatory ability is fabricated. When implanted subcutaneously, MHA-sEVs significantly improve cell infiltration and tissue integration through its macroporous structure. When applied to the osteoporotic RCR model, MHA-sEVs promote TBH by improving tendon repair through macroporous aligned architecture while enhancing bone regeneration by modulating inflammation. Notably, the biomechanical strength of MHA-sEVs is approximately two times higher than the control group, indicating great potential in reducing postoperative retear rates. Further cell-hydrogel interaction studies reveal that the alignment of microfiber gels in MHA-sEVs induces tenogenic differentiation of tendon-derived stem cells, while sEVs improve mitochondrial dysfunction in M1 macrophages (Mφ) and inhibit Mφ polarization toward M1 via nuclear factor-kappaB (NF-κb) signaling pathway. Taken together, MHA-sEVs provide a promising strategy for future clinical application in promoting osteoporotic TBH.

Therapeutic efficacy and promise of stem cell-derived extracellular vesicles in Alzheimer's disease and other aging-related disorders

The term extracellular vesicles (EVs) refers to a variety of heterogeneous nanovesicles secreted by almost all cell types, primarily for intercellular communication and maintaining cellular homeostasis. The role of EVs has been widely reported in the genesis and progression of multiple pathological conditions, and these vesicles are suggested to serve as 'liquid biopsies'. In addition to their use as biomarkers, EVs secreted by specific cell types, especially with stem cell properties, have shown promise as cell-free nanotherapeutics. Stem cell-derived EVs (SC-EVs) have been increasingly used as an attractive alternative to stem cell therapies and have been reported to promote regeneration of aging-associated tissue loss and function. SC-EVs treatment ameliorates brain and peripheral aging, reproductive dysfunctions and inhibits cellular senescence, thereby reversing several aging-related disorders and dysfunctions. The anti-aging therapeutic potential of SC-EVs depends on multiple factors, including the type of stem cells, the age of the source stem cells, and their physiological state. In this review, we briefly describe studies related to the promising effects of SC-EVs against various aging-related pathologies, and then we focus in-depth on the therapeutic benefits of SC-EVs against Alzheimer's disease, one of the most devastating neurodegenerative diseases in elderly individuals. Numerous studies in transgenic mouse models have reported the usefulness of SC-EVs in targeting the pathological hallmarks of Alzheimer's disease, including amyloid plaques, neurofibrillary tangles, and neuroinflammation, leading to improved neuronal protection, synaptic plasticity, and cognitive measures. Cell culture studies have further identified the underlying molecular mechanisms through which SC-EVs reduce amyloid beta (Aβ) levels or shift microglia phenotype from pro-inflammatory to anti-inflammatory state. Interestingly, multiple routes of administration, including nasal delivery, have confirmed that SC-EVs could cross the blood-brain barrier. Due to this, SC-EVs have also been tested to deliver specific therapeutic cargo molecule/s (e.g., neprilysin) to the brain. Despite these promises, several challenges related to quality control, scalability, and biodistribution remain, hindering the realization of the vast clinical promise of SC-EVs.

Hypoxic preconditioned MSCs-derived small extracellular vesicles for photoreceptor protection in retinal degeneration

Photoreceptor apoptosis is an important pathogenesis of retinal degeneration and a primary cause of vision loss with limited treatment methods. Mesenchymal stem/stromal cells-derived small extracellular vesicles (MSC-sEVs) have shown therapeutic value in various ocular disorders. Recent studies have revealed that hypoxic preconditioning can improve the effectiveness of MSC-sEVs in tissue regeneration. However, whether hypoxic preconditioned MSC-sEVs (Hyp-sEVs) exert superior effects on photoreceptor protection relative to normoxic conditioned MSC-sEVs (Nor-sEVs) remains unclear. Here, we reported that Hyp-sEVs further improved retinal structure, recovered retinal function, and suppressed photoreceptor apoptosis in N-methyl-N-nitrosourea (MNU)-induced mouse model compared with Nor-sEVs. Hyp-sEVs also exhibited enhanced anti-apoptotic roles in MNU-provoked 661 W cell injury in vitro. We then analyzed the protein profiles of Nor-sEVs and Hyp-sEVs by LC-MS/MS and found that growth-associated protein 43 (GAP43) was enriched in Hyp-sEVs. The knockdown of GAP43 abolished the retinal therapeutic effects of Hyp-sEVs. Mechanistically, hypoxic stimulation-induced hypoxia-inducible factor-1α (HIF-1α) activation was responsible for preventing tripartite motif-containing protein 25 (TRIM25)-mediated GAP43 ubiquitination and degradation, leading to the upregulation of GAP43 in Hyp-sEVs. Together, our findings uncover the efficacy and mechanism of Hyp-sEVs-based photoreceptor protection and highlight the potential of Hyp-sEVs as optimized therapeutics for retinal degeneration.

Embryonic stem cell-derived extracellular vesicles rejuvenate senescent cells and antagonize aging in mice

Aging is a degenerative process that leads to tissue dysfunction and death. Embryonic stem cells (ESCs) have great therapeutic potential for age-related diseases due to their capacity for self-renewal and plasticity. However, the use of ESCs in clinical treatment is limited by immune rejection, tumourigenicity and ethical issues. ESC-derived extracellular vesicles (EVs) may provide therapeutic effects that are comparable to those of ESCs while avoiding unwanted effects. Here, we fully evaluate the role of ESC-EVs in rejuvenation in vitro and in vivo. Using RNA sequencing (RNA-Seq) and microRNA sequencing (miRNA-Seq) screening, we found that miR-15b-5p and miR-290a-5p were highly enriched in ESC-EVs, and induced rejuvenation by silencing the Ccn2-mediated AKT/mTOR pathway. These results demonstrate that miR-15b-5p and miR-290a-5p function as potent activators of rejuvenation mediated by ESC-EVs. The rejuvenating effect of ESC-EVs was further investigated in vivo by injection into aged mice. The results showed that ESC-EVs successfully ameliorated the pathological age-related phenotypes and rescued the transcriptome profile of aged mice. Our findings demonstrate that ESC-EVs treatment can rejuvenate senescence both in vitro and in vivo and suggest the therapeutic potential of ESC-EVs as a novel cell-free alternative to ESCs for age-related diseases.

Cellular senescence in skeletal disease: mechanisms and treatment

The musculoskeletal system supports the movement of the entire body and provides blood production while acting as an endocrine organ. With aging, the balance of bone homeostasis is disrupted, leading to bone loss and degenerative diseases, such as osteoporosis, osteoarthritis, and intervertebral disc degeneration. Skeletal diseases have a profound impact on the motor and cognitive abilities of the elderly, thus creating a major challenge for both global health and the economy. Cellular senescence is caused by various genotoxic stressors and results in permanent cell cycle arrest, which is considered to be the underlying mechanism of aging. During aging, senescent cells (SnCs) tend to aggregate in the bone and trigger chronic inflammation by releasing senescence-associated secretory phenotypic factors. Multiple signalling pathways are involved in regulating cellular senescence in bone and bone marrow microenvironments. Targeted SnCs alleviate age-related degenerative diseases. However, the association between senescence and age-related diseases remains unclear. This review summarises the fundamental role of senescence in age-related skeletal diseases, highlights the signalling pathways that mediate senescence, and discusses potential therapeutic strategies for targeting SnCs.

Cytokines and exosomal miRNAs in skeletal muscle-adipose crosstalk

Skeletal muscle and adipose tissues (ATs) are secretory organs that release secretory factors including cytokines and exosomes. These factors mediate muscle-adipose crosstalk to regulate systemic metabolism via paracrine and endocrine pathways. Myokines and adipokines are cytokines secreted by skeletal muscle and ATs, respectively. Exosomes loaded with nucleic acids, proteins, lipid droplets, and organelles can fuse with the cytoplasm of target cells to perform regulatory functions. A major regulatory component of exosomes is miRNA. In addition, numerous novel myokines and adipokines have been identified through technological innovations. These discoveries have identified new biomarkers and sparked new insights into the molecular regulation of skeletal muscle growth and adipose deposition. The knowledge may contribute to potential diagnostic and therapeutic targets in metabolic disease.

Mitochondria Transplantation from Stem Cells for Mitigating Sarcopenia

Sarcopenia is defined as the age-related loss of muscle mass and function that can lead to prolonged hospital stays and decreased independence. It is a significant health and financial burden for individuals, families, and society as a whole. The accumulation of damaged mitochondria in skeletal muscle contributes to the degeneration of muscles with age. Currently, the treatment of sarcopenia is limited to improving nutrition and physical activity. Studying effective methods to alleviate and treat sarcopenia to improve the quality of life and lifespan of older people is a growing area of interest in geriatric medicine. Therapies targeting mitochondria and restoring mitochondrial function are promising treatment strategies. This article provides an overview of stem cell transplantation for sarcopenia, including the mitochondrial delivery pathway and the protective role of stem cells. It also highlights recent advances in preclinical and clinical research on sarcopenia and presents a new treatment method involving stem cell-derived mitochondrial transplantation, outlining its advantages and challenges.