Identification of a novel senolytic agent, navitoclax, targeting the Bcl-2 family of anti-apoptotic factors

Transcriptional activation of genes associated with the matrisome is a common feature of senescent endothelial cells

Cellular senescence is a stable cell cycle arrest that occurs in response to various stress stimuli and affects multiple cell types, including endothelial cells (ECs). Senescent cells accumulate with age, and their removal has been linked to reduced age-related diseases. However, some senescent cells are important for tissue homeostasis. Therefore, understanding the diversity of senescent cells in a cell-type-specific manner and their underlying molecular mechanisms is essential. Senescence impairs key ECs functions which are necessary for vascular homeostasis, leading to endothelial dysfunction and age-related vascular diseases. In order to gain insights into these mechanisms, we analyzed publicly available RNA-seq datasets to identify gene expression changes in senescent ECs induced by doxorubicin, irradiation, and replication exhaustion. While only a few genes were consistently differentially expressed across all conditions, some gene ontologies (GO) were shared. Among these, our analysis focused on validating the expression of genes associated with the matrisome, which includes genes encoding for extracellular matrix (ECM) structural components and ECM-associated proteins, in a doxorubicin-induced senescence model. Our results show that the matrisome transcriptome undergoes significant remodeling in senescent endothelial cells, regardless of the specific inducers of senescence, highlighting the importance of understanding how ECM alterations affect senescence.

Cellular Senescence in Health, Disease, and Lens Aging

Background: Cellular senescence is a state of irreversible cell cycle arrest that serves as a critical regulator of tissue homeostasis, aging, and disease. While transient senescence contributes to development, wound healing, and tumor suppression, chronic senescence drives inflammation, tissue dysfunction, and age-related pathologies, including cataracts. Lens epithelial cells (LECs), essential for maintaining lens transparency, are particularly vulnerable to oxidative stress-induced senescence, which accelerates lens aging and cataract formation. This review examines the dual role of senescence in LEC function and its implications for age-related cataractogenesis, alongside emerging senotherapeutic interventions. Methods: This review synthesizes findings on the molecular mechanisms of senescence, focusing on oxidative stress, mitochondrial dysfunction, and the senescence-associated secretory phenotype (SASP). It explores evidence linking LEC senescence to cataract formation, highlighting key studies on stress responses, DNA damage, and antioxidant defense. Recent advances in senotherapeutics, including senolytics and senomorphics, are analyzed for their potential to mitigate LEC senescence and delay cataract progression. Conclusions: LEC senescence is driven by oxidative damage, mitochondrial dysfunction, and impaired redox homeostasis. These factors activate senescence path-ways, including p53/p21 and p16/Rb, resulting in cell cycle arrest and SASP-mediated inflammation. The accumulation of senescent LECs reduces regenerative capacity, disrupts lens homeostasis, and contributes to cataractogenesis. Emerging senotherapeutics, such as dasatinib, quercetin, and metformin, show promise in reducing the senescent cell burden and modulating the SASP to preserve lens transparency.

Injectable Senolytic Hydrogel Depot for the Clearance of Senescent Cells

Small molecules are frontline therapeutics for many diseases; however, they are often limited by their poor solubility. Therefore, hydrophobic small molecules are often encapsulated or prepared as pure drug nanoparticles. Navitoclax, used to eliminate senescent cells, is one such small molecule that faces challenges in translation due to its hydrophobicity and toxic side effects. Further, as senescent cells exhibit context-dependent pathologic or beneficial properties, it is preferable to eliminate senescent cells locally. To formulate navitoclax and enable local treatment, we designed an injectable hydrogel loaded with navitoclax nanoparticles as a senolytic delivery vehicle. Navitoclax nanoparticles (Ø ∼ 110 nm) were prepared via solvent-antisolvent nanoprecipitation and formulated in an injectable polymer-nanoparticle (PNP) hydrogel to create a local senolytic depot. Navitoclax-loaded PNP hydrogels selectively cleared senescent cells in vitro in senescent endothelial monolayers. This work demonstrates the value of formulating lipophilic small molecules and the potential of localized drug delivery strategies to improve senolytic therapies.

Regulatory Network Inference of Induced Senescent Midbrain Cell Types Reveals Cell Type-Specific Senescence-Associated Transcriptional Regulators

Cellular senescence of brain cell types has become an increasingly important perspective for both aging and neurodegeneration, specifically in the context of Parkinson's Disease (PD). The characterization of classical hallmarks of senescence is a widely debated topic, whereby the context in which a senescence phenotype is being investigated, such as the cell type, the inducing stressor, and/or the model system, is an extremely important aspect to consider when defining a senescent cell. Here, we describe a cell type-specific profile of senescence through the investigation of various canonical senescence markers in five human midbrain cell lines using chronic 5-Bromodeoxyuridine (BrdU) treatment as a model of DNA damage-induced senescence. We used principal component analysis (PCA) and subsequent regulatory network inference to define both unique and common senescence profiles in the cell types investigated, as well as revealed senescence-associated transcriptional regulators (SATRs). Functional characterization of one of the identified regulators, transcription factor AP4 (TFAP4), further highlights the cell type-specificity of the expression of the various senescence hallmarks. Our data indicates that SATRs modulate cell type-specific profiles of induced senescence in key midbrain cell types that play an important role in the context of aging and PD.

Senolytic compounds reduce epigenetic age of blood samples in vitro

Senolytic drugs raise the expectation that they can specifically eliminate a subset of senescent cells in a given tissue. In this study, we have exemplarily analyzed if a 3-day treatment of human blood samples in vitro would reduce age-associated biomarkers, with a particular focus on epigenetic age-predictions. Of eight tested compounds, JQ1, RG7112, nutlin-3a, and AMG232 reduced epigenetic age, indicating that this approach may be useful in drug screening for senolytic compounds.

Senescent cells as a target for anti-aging interventions: From senolytics to immune therapies

Aging and age-related diseases are major drivers of multimorbidity and mortality worldwide. Cellular senescence is a hallmark of aging. The accumulation of senescent cells is causally associated with pathogenesis of various age-associated disorders. Due to their promise for alleviating age-related disorders and extending healthspan, therapeutic strategies targeting senescent cells (senotherapies) as a means to combat aging have received much attention over the past decade. Among the conventionally used approaches, one is the usage of small-molecule compounds to specifically exhibit cytotoxicity toward senescent cells or inhibit deleterious effects of the senescence-associated secretory phenotype (SASP). Alternatively, there are immunotherapies directed at surface antigens specifically upregulated in senescent cells (seno-antigens), including chimeric antigen receptor (CAR) therapies and senolytic vaccines. This review gives an update of the current status in the discovery and development of senolytic therapies, and their translational progress from preclinical to clinical trials. We highlight the current challenges faced by senotherapeutic development in the context of senescence heterogeneity, with the aim of offering novel perspectives for future anti-aging interventions aimed at enhancing healthy longevity.

Improved Therapeutic Efficiency of Senescent Cell-specific, Galactose-Functionalized Micelle Nanocarriers

Cellular senescence has recently been recognized as one of the hallmarks of cancer, aging, as well as many age-related disorders, sparking significant interest in the development of senolytics, compounds that can remove senescent cells. However, most current pharmacological strategies face challenges related to non-specific delivery, leading to significant side effects that hinder safe and effective treatments. To address these issues, galactose-functionalized amphiphiles are synthesized that can self-assemble into micelles and be loaded with a senolytic cargo. These galactose-micelles are responsive to the lysosomal β-galactosidase enzyme, present in elevated amounts in senescent cells, and are employed for specific delivery of the senolytic Bcl2-inhibitor Navitoclax. This novel formulation showed reduced delivery and toxicity to non-senescent cells, thereby increasing the senolytic index of Navitoclax and making it suitable for future in vivo experimental designs to improve selectivity and safety profiles.

Pathogenesis and inflammaging in myelodysplastic syndrome

Myelodysplastic syndromes (MDS) are a genetically complex and phenotypically diverse set of clonal hematologic neoplasms that occur with increasing frequency with age. MDS has long been associated with systemic inflammatory conditions and disordered inflammatory signaling is implicated in MDS pathogenesis. A rise in sterile inflammation occurs with ageing and the term "inflammaging" has been coined by to describe this phenomenon. This distinct form of sterile inflammation has an unknown role in in the pathogenesis of myeloid malignancies despite shared correlations with age and ageing-related diseases. More recent is a discovery that many cases of MDS arise from clonal hematopoiesis of indeterminate potential (CHIP), an age associated, asymptomatic pre-disease state. The interrelationship between ageing, inflammation and clonal CHIP is complex and likely bidirectional with causality between inflammaging and CHIP potentially instrumental to understanding MDS pathogenesis. Here we review the concept of inflammaging and MDS pathogenesis and explore their causal relationship by introducing a novel framing mechanism of "pre-clonal inflammaging" and "clonal inflammaging". We aim to harmonize research on ageing, inflammation and MDS pathogenesis by contextualizing the current understanding of inflammaging and the ageing hematopoietic system with what is known about the etiology of MDS via its progression from CHIP.

Cellular senescence contributes to spontaneous repair of the rat meniscus

Cellular senescence, traditionally associated with aging and chronic diseases, has recently been identified as a potential facilitator of tissue regeneration via a senescence-associated secretory phenotype (SASP). In rodents, the meniscus is known to regenerate spontaneously from the surrounding synovium, but the mechanism, and especially its relationship to cellular senescence, remains unclear. This study investigated the contribution of cellular senescence to spontaneous repair of the rat meniscus. We created a rat partial medial meniscectomy (pMx) model to evaluate time-course changes in regenerative tissue. Immunohistochemistry revealed marked increases in p16 expression and senescence-associated beta-galactosidase (SA-β-gal) activity in the regenerating tissue at the early phase after pMx surgery. RNA sequencing of regenerating tissues identified the upregulation of genes related to aging, extracellular matrix organization, and cell proliferation. Fluorescence staining identified high expression of SOX9, a master regulator of cartilage/meniscus development, adjacent to p16-positive cells. In vitro investigations of the effect of SASP factors on synovial fibroblasts (SFs) demonstrated that conditioned medium from senescent SFs stimulated the proliferation and chondrogenic differentiation of normal SFs. In vivo histological evaluation to determine whether selective elimination of senescent cells with a senolytic drug (ABT-263) retarded spontaneous repair of meniscus in vivo confirmed that ABT-263 decreased the meniscus score and expression of SOX9, aggrecan, and type 1 collagen. Our findings indicate that transient senescent cell accumulation and SASP in regenerating tissues beneficially contribute to spontaneous repair of the rat meniscus. Further research into the molecular mechanism will provide a novel strategy for meniscus regeneration based on cellular senescence.

Cell Senescence-Related Genes as Biomarkers for Prognosis and Immunotherapeutic Response in Colon Cancer

Colon adenocarcinoma (COAD) stands out as the most prevalent malignancy diagnosed within the gastrointestinal tract, bearing substantial incidence and mortality rates. The processes of ageing and senescence intricately intertwine with tumorigenesis and immune regulation, concurrently exerting influence on the remodelling of the tumor microenvironment (TME). This phenomenon, in turn, significantly impacts the efficacy of immunotherapeutic interventions. Despite this awareness, the comprehensive understanding of the intricate interplay between cellular senescence and TME in the context of COAD remains elusive. Further inquiry is imperative to comprehensively gauge the relevance of cellular senescence-related genes (CSGs) in the realms of immune infiltration and the prognostication of COAD. Differentially expressed cell senescence-related genes (DE-CSGs) within COAD tumors and normal specimens were discerned through analysis of the TCGA-COAD dataset. Leveraging univariate, LASSO, and multivariate Cox regression analyses, we formulated a prognostic risk signature. Subsequent validation utilised two independent GEO datasets. Furthermore, a nomogram was devised to gauge the prognostic significance of this signature. Additionally, the immune landscape of the Cell Senescence-related Signature (CSS) was characterised using CIBERSORT and TIMER algorithms. The expression levels of CSGs were quantified through RT-PCR in COAD specimens. Drawing upon mRNA expression profiles of 191 DE-CSGs, we successfully established a 9-gene CSS, demonstrating its autonomy as a prognostic determinant for COAD patients. Those assigned high-risk scores exhibited an immunosuppressive phenotype, marked by elevated proportions of resting CD4+memory T cells and macrophages M0, correlating with diminished overall survival. Subsequent analyses uncovered that the amalgamation of CSS with the expression profiles of immune checkpoint key genes effectively predicted patient prognosis. Furthermore, patients with low-risk scores demonstrated a potential association with more favourable therapeutic outcomes in the context of immunotherapy. This study has culminated in the development of a prognostic risk signature grounded in cell senescence-related genes for COAD. We posit that the CSS plays a regulatory role in immune infiltration, emerging as a robust biomarker for prognosis and a predictive indicator for immunotherapeutic responsiveness within the COAD landscape.

Advancements in programmed cell death research in antitumor therapy: a comprehensive overview

Cell death is a normal physiological process within cells that involves multiple pathways, such as normal DNA damage, cell cycle arrest, and programmed cell death (PCD). Cell death has been a hot spot of research in tumor-related fields, especially programmed cell death, which is a key form of cell death and is classified into different types according to the mechanism of occurrence, such as apoptosis, autophagy, necroptosis, pyroptosis, ferroptosis, and disulfidptosis. Given the important role of PCD in maintaining tissue homeostasis and inhibiting tumorigenesis and development, more and more basic and clinical studies are devoted to revealing its potential application in anti-tumor strategies. The purpose of this review is to systematically review the regulatory mechanisms of PCD and to summarize the latest research progress of anti-tumor treatment strategies based on PCD.

Genetically engineered CD276-anchoring biomimetic nanovesicles target senescent escaped tumor cells to overcome chemoresistant and immunosuppressive breast cancer

Chemotherapy-induced cellular senescence leads to an increased proportion of cancer stem cells (CSCs) in breast cancer (BC), contributing to recurrence and metastasis, while effective means to clear them are currently lacking. Herein, we aim to develop new approaches for selectively killing senescent-escape CSCs. High CD276 (95.60%) expression in multidrug-resistant BC cells, facilitates immune evasion by low-immunogenic senescent escape CSCs. CALD1, upregulated in ADR-resistant BC, promoting senescent-escape of CSCs with an anti-apoptosis state and upregulating CD276, PD-L1 to promote chemoresistance and immune escape. We have developed a controlled-released thermosensitive hydrogel containing pH- responsive anti-CD276 scFV engineered biomimetic nanovesicles to overcome BC in primary, recurrent, metastatic and abscopal humanized mice models. Nanovesicles coated anti-CD276 scFV selectively fuses with cell membrane of senescent-escape CSCs, then sequentially delivers siCALD1 and ADR due to pH-responsive MnP shell. siCALD1 together with ADR effectively induce apoptosis of CSCs, decrease expression of CD276 and PD-L1, and upregulate MHC I combined with Mn2+ to overcome chemoresistance and promote CD8+T cells infiltration. This combined therapeutic approach reveals insights into immune surveillance evasion by senescent-escape CSCs, offering a promising strategy to immunotherapy effectiveness in cancer therapy.

Carbohydrate polymer-based nanoparticles with cell membrane camouflage for cancer therapy: A review

Recent developments in biomimetic nanoparticles, specifically carbohydrate polymer-coated cell membrane nanoparticles, have demonstrated considerable promise in treating cancer. These systems improve drug delivery by imitating natural cell actions, enhancing biocompatibility, and decreasing immune clearance. Conventional drug delivery methods frequently face challenges with non-specific dispersal and immune detection, which can hinder their efficiency and safety. These biomimetic nanoparticles improve target specificity, retention times, and therapeutic efficiency by using biological components like chitosan, hyaluronic acid, and alginate. Chitosan-based nanoparticles, which come from polysaccharides found in nature, have self-assembly abilities that make them better drug carriers. Hyaluronic acid helps target tissues more effectively, especially in cancer environments where there are high levels of hyaluronic acid receptors. Alginate-based systems also enhance drug delivery by being biocompatible and degradable, making them ideal choices for advanced therapeutic uses. Moreover, these particles hold potential for overcoming resistance to multiple drugs and boosting the body's immune reaction to tumors through precise delivery and decreased side effects of chemotherapy drugs. This review delves into the possibilities of using carbohydrate polymer-functionalized nanoparticles and their impact on enhancing the efficacy of cancer treatment.

H4K20me3-Mediated Repression of Inflammatory Genes Is a Characteristic and Targetable Vulnerability of Persister Cancer Cells

Anticancer therapies can induce cellular senescence or drug-tolerant persistence, two types of proliferative arrest that differ in their stability. While senescence is highly stable, persister cells efficiently resume proliferation upon therapy termination, resulting in tumor relapse. Here, we used an ATP-competitive mTOR inhibitor to induce and characterize persistence in human cancer cells of various origins. Using this model and previously described models of senescence, we compared the same cancer cell lines under the two types of proliferative arrest. Persister and senescent cancer cells shared an expanded lysosomal compartment and hypersensitivity to BCL-XL inhibition. However, persister cells lacked other features of senescence, such as loss of lamin B1, senescence-associated β-galactosidase activity, upregulation of MHC-I, and an inflammatory and secretory phenotype (senescence-associated secretory phenotype or SASP). A genome-wide CRISPR/Cas9 screening for genes required for the survival of persister cells revealed that they are hypersensitive to the inhibition of one-carbon (1C) metabolism, which was validated by the pharmacologic inhibition of serine hydroxymethyltransferase, a key enzyme that feeds methyl groups from serine into 1C metabolism. Investigation into the relationship between 1C metabolism and the epigenetic regulation of transcription uncovered the presence of the repressive heterochromatic mark H4K20me3 at the promoters of SASP and IFN response genes in persister cells, whereas it was absent in senescent cells. Moreover, persister cells overexpressed the H4K20 methyltransferases KMT5B/C, and their downregulation unleashed inflammatory programs and compromised the survival of persister cells. In summary, this study identifies distinctive features and actionable vulnerabilities of persister cancer cells and provides mechanistic insight into their low inflammatory activity. Significance: Cell persistence and senescence are distinct states of proliferative arrest induced by cancer therapy, with persister cells being characterized by the silencing of inflammatory genes through the heterochromatic mark H4K20me3. See related commentary by Schmitt, p. 7.

A chimeric peptide promotes immune surveillance of senescent cells in injury, fibrosis, tumorigenesis and aging

The accumulation of senescent cells can lead to tissue degeneration, chronic inflammatory disease and age-related tumorigenesis. Interventions such as senolytics are currently limited by off-target toxicity, which could be circumvented by instead enhancing immune-mediated senescent cell clearance; however, immune surveillance of senescent cells is often impeded by immunosuppressive factors in the inflammatory microenvironment. Here, we employ a chimeric peptide as a 'matchmaker' to bind to the urokinase-type plasminogen activator receptor, a cell surface marker of senescent cells. This peptide modifies the cell surface with polyglutamic acid, promoting immune cell-mediated responses through glutamate recognition. By enhancing the recruitment of immune cells and directly coupling senescent cells and immune cells, we show that this chimeric peptide induces immune clearance of senescent cells and restores tissue homeostasis in conditions such as liver fibrosis, lung injury, cancer and natural aging in mice. This chimeric peptide introduces an immunological conversion strategy that rebalances the senescent immune microenvironment, offering a promising direction for aging immunotherapy.

Exploring the Mechanisms of Sanguinarine in the Treatment of Osteoporosis by Integrating Network Pharmacology Analysis and Deep Learning Technology

BACKGROUND

Sanguinarine (SAN) has been reported to have antioxidant, antiinflammatory, and antimicrobial activities with potential for the treatment of osteoporosis (OP).

OBJECTIVE

This work purposed to unravel the molecular mechanisms of SAN in the treatment of OP.

METHODS

OP-related genes and SAN-related targets were predicted from public databases. Differential expression analysis and VennDiagram were adopted to detect SAN-related targets against OP. Protein-protein interaction (PPI) network was served for core target identification. Molecular docking and DeepPurpose algorithm were further adopted to investigate the binding ability between core targets and SAN. Gene pathway scoring of these targets was calculated utilizing gene set variation analysis (GSVA). Finally, we explored the effect of SAN on the expressions of core targets in preosteoblastic MC3T3-E1 cells.

RESULTS

A total of 21 candidate targets of SAN against OP were acquired. Furthermore, six core targets were identified, among which CASP3, CTNNB1, and ERBB2 were remarkably differentially expressed in OP and healthy individuals. The binding energies of SAN with CASP3, CTNNB1, and ERBB2 were -6, -6.731, and -7.162 kcal/mol, respectively. Moreover, the GSVA scores of the Wnt/calcium signaling pathway were significantly lower in OP cases than in healthy individuals. In addition, the expression of CASP3 was positively associated with Wnt/calcium signaling pathway. CASP3 and ERBB2 were significantly lower expressed in SAN group than in DMSO group, whereas the expression of CTNNB1 was in contrast.

CONCLUSION

CASP3, CTNNB1, and ERBB2 emerge as potential targets of SAN in OP prevention and treatment.

Natural Product-Derived Senotherapeutics: Extraction and Biological Evaluation Techniques

Selective targeting of senescent cells has been thus far considered a widespread preventive strategy, as well as a main or adjuvant therapy for age-associated diseases, fueling the research on the discovery of senotherapeutics (i.e., senolytic or senomorphic compounds). Given that until now no single senotherapeutic has been reported to exert a universal anti-senescence action due to the cell- /tissue-, and context-dependent specificity of such compounds, seeking novel selective senotherapeutics remains of great importance. In this chapter, a research strategy that could be followed to screen natural product collections for putative senotherapeutics with enhanced specificity and reduced toxicity is presented, from the extraction of the source material and the isolation and chemical characterization of the compounds of interest to their biological evaluation in vitro and in vivo.

Uncovering cellular senescence as a therapeutic target in NF2-related vestibular schwannoma

BACKGROUND

Vestibular schwannomas (VS) are complex and heterogeneous human tumors arising from the Schwann cell compartment of the vestibulocochlear nerve. VS cause significant neurological deficit such as hearing loss and vestibular impairment, and in some cases death due to brainstem compression. There is an urgent need to find pharmacotherapies for VS since surgical removal and stereotactic radiosurgery are the only effective treatments. Cancer therapy based in the combination of drug-induced senescence and senolytics may provide an innovative pharmacological alternative for VS management.

METHODS

Senescence-associated β-galactosidase (SA-β-GAL) activity detection assay, real-time polymerase chain reaction (RT-PCR), western blotting and immunofluorescence, together with viability assays were used to analyze the response to different chemotherapy drugs of the human VS HEI-193 cell line. Human VS tumor paraffin sections were also studied for SA-β-GAL-stained cells.

RESULTS

We found that chemotherapy compounds induced genotoxic stress and cellular senescence in HEI-193 VS cells, as characterized by increased SA-β-GAL activity, growth arrest, increased levels of the cyclin-dependent kinase inhibitor p21 and the accumulation of DNA damage. These cellular senescence markers were also accompanied by an increase of senescence-associated secretory phenotype (SASP): IL6, IL8, IL1B and MMP1. Induction of senescence by chemotherapy rendered HEI-193 VS cells as druggable targets for senolytic compounds, as navitoclax. Thus, treatment with navitoclax selectively eliminated bleomycin-induced senescent HEI-193 VS cells by activating the extrinsic and intrinsic apoptosis pathways. Our data also show the presence of senescent cells, SA-β-GAL-positive stain, in human VS tumors, which are not present in healthy great auricular nerve sections.

CONCLUSIONS

These findings suggest that a one-two punch strategy of pro-senescence therapy induced by chemotherapy treatment followed by senolytic therapy represents a new paradigm for the pharmacological treatment of VS.

The crosstalk between senescence, tumor, and immunity: molecular mechanism and therapeutic opportunities

Cellular senescence is characterized by a stable cell cycle arrest and a hypersecretory, proinflammatory phenotype in response to various stress stimuli. Traditionally, this state has been viewed as a tumor-suppressing mechanism that prevents the proliferation of damaged cells while activating the immune response for their clearance. However, senescence is increasingly recognized as a contributing factor to tumor progression. This dual role necessitates a careful evaluation of the beneficial and detrimental aspects of senescence within the tumor microenvironment (TME). Specifically, senescent cells display a unique senescence-associated secretory phenotype that releases a diverse array of soluble factors affecting the TME. Furthermore, the impact of senescence on tumor-immune interaction is complex and often underappreciated. Senescent immune cells create an immunosuppressive TME favoring tumor progression. In contrast, senescent tumor cells could promote a transition from immune evasion to clearance. Given these intricate dynamics, therapies targeting senescence hold promise for advancing antitumor strategies. This review aims to summarize the dual effects of senescence on tumor progression, explore its influence on tumor-immune interactions, and discuss potential therapeutic strategies, alongside challenges and future directions. Understanding how senescence regulates antitumor immunity, along with new therapeutic interventions, is essential for managing tumor cell senescence and remodeling the immune microenvironment.

Senescence as a therapeutic target in cancer and age-related diseases

Cellular senescence is a stress response that restrains the growth of aged, damaged or abnormal cells. Thus, senescence has a crucial role in development, tissue maintenance and cancer prevention. However, lingering senescent cells fuel chronic inflammation through the acquisition of a senescence-associated secretory phenotype (SASP), which contributes to cancer and age-related tissue dysfunction. Recent progress in understanding senescence has spurred interest in the development of approaches to target senescent cells, known as senotherapies. In this Review, we evaluate the status of various types of senotherapies, including senolytics that eliminate senescent cells, senomorphics that suppress the SASP, interventions that mitigate senescence and strategies that harness the immune system to clear senescent cells. We also summarize how these approaches can be combined with cancer therapies, and we discuss the challenges and opportunities in moving senotherapies into clinical practice. Such therapies have the potential to address root causes of age-related diseases and thus open new avenues for preventive therapies and treating multimorbidities.

Senescent cell depletion alleviates obesity-related metabolic and cardiac disorders

Obesity is a major contributor to metabolic and cardiovascular disease. Although senescent cells have been shown to accumulate in adipose tissue, the role of senescence in obesity-induced metabolic disorders and in cardiac dysfunction is not yet clear; therefore, the therapeutic potential of managing senescence in obesity-related metabolic and cardiac disorders remains to be fully defined.

OBJECTIVE

We investigated the beneficial effects of a senolytic cocktail (dasatinib and quercetin) on senescence and its influence on obesity-related parameters.

METHODS AND RESULTS

We found that the increase in body weight and adiposity, glucose intolerance, insulin resistance, dyslipidemia, hyperleptinemia, and hepatic disorders which were induced by an obesogenic diet were alleviated by senolytic cocktail treatment in mice. Treatment with senolytic compounds eliminated senescent cells, counteracting the activation of the senescence program and DNA damage in white adipose tissue (WAT) observed with an obesogenic diet. Moreover, the senolytic cocktail prevented the brown adipose tissue (BAT) whitening and increased the expression of the thermogenic gene profile in BAT and pWAT. In the hearts of obese mice, senolytic combination abolished myocardial maladaptation, reducing the senescence-associated secretory phenotype (SASP) and DNA damage, repressing cardiac hypertrophy, and improving diastolic dysfunction. Additionally, we showed that treatment with the senolytic cocktail corrected gene expression programs associated with fatty acid metabolism, oxidative phosphorylation, the P53 pathway, and DNA repair, which were all downregulated in obese mice.

CONCLUSIONS

Collectively, these data suggest that a senolytic cocktail can prevent the activation of the senescence program in the heart and WAT and activate the thermogenic program in BAT. Our results suggest that targeting senescent cells may be a novel therapeutic strategy for alleviating obesity-related metabolic and cardiac disorders.

The Intersection of Epigenetics and Senolytics in Mechanisms of Aging and Therapeutic Approaches

The biological process of aging is influenced by a complex interplay of genetic, environmental, and epigenetic factors. Recent advancements in the fields of epigenetics and senolytics offer promising avenues for understanding and addressing age-related diseases. Epigenetics refers to heritable changes in gene expression without altering the DNA sequence, with mechanisms like DNA methylation, histone modification, and non-coding RNA regulation playing critical roles in aging. Senolytics, a class of drugs targeting and eliminating senescent cells, address the accumulation of dysfunctional cells that contribute to tissue degradation and chronic inflammation through the senescence-associated secretory phenotype. This scoping review examines the intersection of epigenetic mechanisms and senolytic therapies in aging, focusing on their combined potential for therapeutic interventions. Senescent cells display distinct epigenetic signatures, such as DNA hypermethylation and histone modifications, which can be targeted to enhance senolytic efficacy. Epigenetic reprogramming strategies, such as induced pluripotent stem cells, may further complement senolytics by rejuvenating aged cells. Integrating epigenetic modulation with senolytic therapy offers a dual approach to improving healthspan and mitigating age-related pathologies. This narrative review underscores the need for continued research into the molecular mechanisms underlying these interactions and suggests future directions for therapeutic development, including clinical trials, biomarker discovery, and combination therapies that synergistically target aging processes.

Topical ABT-263 treatment reduces aged skin senescence and improves subsequent wound healing

Senescent cells accumulate in aging tissues, impairing their ability to undergo repair and regeneration following injury. Previous research has demonstrated that targeting tissue senescence with senolytics can enhance tissue regeneration and repair by selectively eliminating SnCs in specific aged tissues. In this study, we focused on eliminating senescent skin cells in aged mice to assess the effects on subsequent wound healing. We applied ABT-263 directly to the skin of 24-month-old mice over a 5-day period. Following topical ABT-263, aged skin demonstrated decreased gene expression of senescence markers p16 and p21, accompanied by reductions in SA-β-gal- and p21-positive cells compared to DMSO controls. However, ABT-263 also triggered a temporary inflammatory response and macrophage infiltration in the skin. Bulk RNA sequencing of ABT-263-treated skin revealed prompt upregulation of genes associated with wound healing pathways, including hemostasis, inflammation, cell proliferation, angiogenesis, collagen synthesis, and extracellular matrix organization. Aged mice skin pre-treated with topical ABT-263 exhibited accelerated wound closure. In conclusion, topical ABT-263 effectively reduced several senescence markers in aged skin, thereby priming the skin for improved subsequent wound healing. This enhancement may be attributed to ABT-263-induced senolysis which in turn stimulates the expression of genes involved in extracellular matrix remodeling and wound repair pathways.

Podocyte senescence: from molecular mechanisms to therapeutics

As an important component of the glomerular filtration membrane, the state of the podocytes is closely related to kidney function, they are also key cells involved in aging and play a central role in the damage caused by renal aging. Therefore, understanding the aging process of podocytes will allow us to understand their susceptibility to injury and identify targeted protective mechanisms. In fact, the process of physiological aging itself can induce podocyte senescence. Pathological stresses, such as oxidative stress, mitochondrial damage, secretion of senescence-associated secretory phenotype, reduced autophagy, oncogene activation, altered transcription factors, DNA damage response, and other factors, play a crucial role in inducing premature senescence and accelerating aging. Senescence-associated-β-galactosidase (SA-β-gal) is a marker of aging, and β-hydroxybutyric acid treatment can reduce SA-β-gal activity to alleviate cellular senescence and damage. In addition, CCAAT/enhancer-binding protein-α, transforming growth factor-β signaling, glycogen synthase kinase-3β, cycle-dependent kinase, programmed cell death protein 1, and plasminogen activator inhibitor-1 are closely related to aging. The absence or elevation of these factors can affect aging through different mechanisms. Podocyte injury is not an independent process, and injured podocytes interact with the surrounding epithelial cells or other kidney cells to mediate the injury or loss of podocytes. In this review, we discuss the manifestations, molecular mechanisms, biomarkers, and therapeutic drugs for podocyte senescence. We included elamipretide, lithium, calorie restriction, rapamycin; and emerging treatment strategies, such as gene and immune therapies. More importantly, we summarize how podocyte interact with other kidney cells.

Effects of triggers of senescence and senolysis in murine pancreatic cancer cells

BACKGROUND

The combination of senescence triggers with senolytic drugs is considered a promising new approach to cancer therapy. Here, we studied the efficacy of the genotoxic agent etoposide (Eto) and irradiation in inducing senescence of Panc02 pancreatic cancer cells, and the capability of the Bcl-2 inhibitor navitoclax (ABT-263; Nav) to trigger senolysis.

METHODS

Panc02 cells were treated with Eto or irradiated with 5-20 Gy before exposure to Nav. Cell survival, proliferation, and senescence were assessed by trypan blue staining, quantification of DNA synthesis, and staining of senescence-associated β-galactosidase (SA-β-Gal)-positive cells, respectively. Levels of mRNA were determined by real-time polymerase chain reaction, and protein expression was analyzed by immunoblotting. Panc02 cells were also grown as pancreatic tumors in mice, which were subsequently treated with Eto and Nav.

RESULTS

Eto and irradiation had an antiproliferative effect on Panc02 cells that was significantly or tendentially enhanced by Nav. In vivo, Eto and Nav together, but not Eto alone, significantly reduced the proportion of proliferating cells. The expression of the senescence marker γH2AX and tumor infiltration with T-cells were not affected by the treatment. In vitro, almost all Eto-exposed cells and a significant proportion of cells irradiated with 20 Gy were SA-β-Gal-positive. Application of Nav reduced the percentage of SA-β-Gal-positive cells after irradiation but not after pretreatment with Eto. In response to triggers of senescence, cultured Panc02 cells showed increased protein levels of γH2AX and the autophagy marker LC3B-II, and higher mRNA levels of Cdkn1a, Mdm2, and PAI-1, while the effects of Nav were variable.

CONCLUSIONS

In vitro and in vivo, the combination of senescence triggers with Nav inhibited tumor cell growth more effectively than the triggers alone. Our data also provide some evidence for senolytic effects of Nav in vitro.

Oxidative stress and cell senescence as drivers of ageing: Chicken and egg

Oxidative stress and cell senescence are both important drivers of ageing and age-associated disease and disability. In vitro, they are closely interconnected in a chicken-and-egg relationship: Not only is oxidative stress an important cause of cell senescence, but senescent cells are also sources of oxidative stress, obscuring cause-effect relationships during the ageing process. We hypothesize that cell senescence is a significant cause of tissue and systemic oxidative stress during ageing. This review aims to critically summarize the available evidence for this hypothesis. After summarizing the cellular feedback mechanisms that make oxidative stress an integral part of the senescent phenotype, it critically reviews the existing evidence for a role of senescent cells as causes of oxidative stress during mammalian ageing in vivo, focussing on results from intervention experiments. It is concluded that while the available data are in agreement with this hypothesis, they are still too scarce to support a robust conclusion.

Impacts of Senolytic Phytochemicals on Gut Microbiota: A Comprehensive Review

There is increasing interest in utilizing senolytics to selectively remove senescent cells from intestinal tissues, with the aim of maintaining a healthy gut environment during aging. This strategy underscores the potential of senolytics to enhance gut health by delaying intestinal aging and positively modulating gut microbiota. Certain plant-based phytochemicals have demonstrated promising senolytic effects. Beyond their ability to eliminate senescent cells, these compounds also exhibit antioxidant and anti-inflammatory properties, reducing oxidative stress and inflammation-key drivers of age-related diseases. By selectively removing senescent cells from the intestine, senolytic phytochemicals contribute to an improved intestinal inflammatory environment and promote the growth of a diverse microbial community. Ultimately, the dietary intake of these senolytic phytochemicals aids in maintaining a healthier intestinal microenvironment by targeting and clearing aged enterocytes.

Molecular and Cellular Foundations of Aging of the Brain: Anti-aging Strategies in Alzheimer's Disease

Alzheimer's disease (AD) is a condition characterized by the gradual degeneration of the nervous system that poses significant challenges to cognitive function and overall mental health. Given the increasing global life expectancy, there is an urgent need for effective strategies to prevent and manage Alzheimer's disease, with a particular focus on anti-aging interventions. Recent scientific advancements have unveiled several promising strategies for combating Alzheimer's disease (AD), ranging from lifestyle interventions to cutting-edge pharmacological treatments and therapies targeting the underlying biological processes of aging and AD. Regular physical exercise, cognitive engagement, a balanced diet, and social interaction serve as key pillars in maintaining brain health. At the same time, therapies target key pathological mechanisms of AD, such as amyloid-beta accumulation, tau abnormalities, neuroinflammation, mitochondrial dysfunction, and synaptic loss, offering potential breakthroughs in treatment. Moreover, cutting-edge innovations such as gene therapy, stem cell transplantation, and novel drug delivery systems are emerging as potential game-changers in the fight against AD. This review critically evaluates the latest research on anti-aging interventions and their potential in preventing and treating Alzheimer's disease (AD) by exploring the connections between aging mechanisms and AD pathogenesis. It provides a comprehensive analysis of both well-established and emerging strategies, while also identifying key gaps in current knowledge to guide future research efforts.

Decoding senescence of aging single cells at the nexus of biomaterials, microfluidics, and spatial omics

Aging has profound effects on the body, most notably an increase in the prevalence of several diseases. An important aging hallmark is the presence of senescent cells that no longer multiply nor die off properly. Another characteristic is an altered immune system that fails to properly self-surveil. In this multi-player aging process, cellular senescence induces a change in the secretory phenotype, known as senescence-associated secretory phenotype (SASP), of many cells with the intention of recruiting immune cells to accelerate the clearance of these damaged senescent cells. However, the SASP phenotype results in inducing secondary senescence of nearby cells, resulting in those cells becoming senescent, and improper immune activation resulting in a state of chronic inflammation, called inflammaging, in many diseases. Senescence in immune cells, termed immunosenescence, results in further dysregulation of the immune system. An interdisciplinary approach is needed to physiologically assess aging changes of the immune system at the cellular and tissue level. Thus, the intersection of biomaterials, microfluidics, and spatial omics has great potential to collectively model aging and immunosenescence. Each of these approaches mimics unique aspects of the body undergoes as a part of aging. This perspective highlights the key aspects of how biomaterials provide non-cellular cues to cell aging, microfluidics recapitulate flow-induced and multi-cellular dynamics, and spatial omics analyses dissect the coordination of several biomarkers of senescence as a function of cell interactions in distinct tissue environments. An overview of how senescence and immune dysregulation play a role in organ aging, cancer, wound healing, Alzheimer's, and osteoporosis is included. To illuminate the societal impact of aging, an increasing trend in anti-senescence and anti-aging interventions, including pharmacological interventions, medical procedures, and lifestyle changes is discussed, including further context of senescence.

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.

Emerging insights in senescence: pathways from preclinical models to therapeutic innovations

Senescence is a crucial hallmark of ageing and a significant contributor to the pathology of age-related disorders. As committee members of the young International Cell Senescence Association (yICSA), we aim to synthesise recent advancements in the identification, characterisation, and therapeutic targeting of senescence for clinical translation. We explore novel molecular techniques that have enhanced our understanding of senescent cell heterogeneity and their roles in tissue regeneration and pathology. Additionally, we delve into in vivo models of senescence, both non-mammalian and mammalian, to highlight tools available for advancing the contextual understanding of in vivo senescence. Furthermore, we discuss innovative diagnostic tools and senotherapeutic approaches, emphasising their potential for clinical application. Future directions of senescence research are explored, underscoring the need for precise, context-specific senescence classification and the integration of advanced technologies such as machine learning, long-read sequencing, and multifunctional senoprobes and senolytics. The dual role of senescence in promoting tissue homoeostasis and contributing to chronic diseases highlights the complexity of targeting these cells for improved clinical outcomes.

Senolytic Prodrugs: A Promising Approach to Enhancing Senescence-Targeting Intervention

Cellular senescence has emerged as a potential therapeutic target for aging and a wide range of age-related disorders. Despite the encouraging therapeutic impact of senolytic agents on improving lifespan and the outcomes of pharmacological intervention, the senolytic induced side effects pose barriers to clinical application. There is a pressing need for selective ablation of senescent cells (SnCs). The design of senolytic prodrugs has been demonstrated as a promising approach to addressing these issues. These prodrugs are generally designed via modification of senolytics with a cleavable galactose moiety to respond to the senescent biomarker - senescence-associated β-galactosidase (SA-β-gal) to restore their therapeutic effects. In this Concept, we summarize the developments by categorizing these prodrugs into two classes: 1) galactose-modified senolytic prodrugs, in which sensing unit galactose is either directly conjugated to the drug or via a self-immolative linker and 2) bioorthogonal activation of senolytic prodrugs. In the bioorthogonal prodrug design, galactose is incorporated into dihydrotetrazine to sense SA-β-gal for click activation. Notably, in addition to repurposed chemotherapeutics and small molecule inhibitors, PROTACs and photodynamic therapy have been introduced as new senolytics in the prodrug design. It is expected that the senolytic prodrugs would facilitate translating small-molecule senolytics into clinical use.

Involvement of cellular senescence in the effect of X-irradiated human lung fibroblast WI-38 cells on human lung cancer A549 cell clonogenic potential

Ionizing radiation not only affects irradiated but also non-irradiated surrounding cells through intercellular communication, indicating that the former cells could affect the latter. The present study investigated the effect of X-irradiated normal human lung fibroblast WI-38 cells on the clonofenic potential of human lung cancer A549 cells by co-culturing them. Moreover, the relationship between the effects of co-culturing on the clonogenic potential of A549 cells and cellular senescence in WI-38 cells was investigated. The co-culture with 10-Gy-irradiated WI-38 cells and A549 cells enhanced the clonogenic potential of non- or X-irradiated A549 cells. Irradiated WI-38 cells exhibited high SA-β-gal activity, a cellular senescence hallmark. Importantly, treatment with senolytic drugs, which eliminate senescent cells, not only influenced high-SA-β-gal-activity cell percentages among the irradiated WI-38 cells but also the effect of irradiated WI-38 cells on the clonogenic potential of A549 cells. In conclusion, our results suggest that irradiated WI-38 cells promote A549 cell clonogenic potential and irradiated senescent WI-38 cells contribute to this effect.

All-trans retinoic acid inhibits glioblastoma progression and attenuates radiation-induced brain injury

Radiotherapy (RT) remains a primary treatment modality for glioblastoma (GBM), but it induces cellular senescence and is strongly implicated in GBM progression and RT-related injury. Recently, eliminating senescent cells has emerged as a promising strategy for treating cancer and for mitigating radiation-induced brain injury (RBI). Here, we investigated the impact of all-trans retinoic acid (RA) on radiation-induced senescence. The findings of this study revealed that RA effectively eliminated astrocytes, which are particularly prone to senescence after radiation, and that the removal of senescence-associated secretory phenotype factor-producing astrocytes inhibited GBM cell proliferation in vitro. Moreover, RA-mediated clearance of senescent cells improved survival in GBM-bearing mice and alleviated radiation-induced cognitive impairment. Through RNA sequencing, we found that the AKT/mTOR/PPARγ/Plin4 signaling pathway is involved in RA-mediated clearance of senescent cells. In summary, these results suggest that RA could be a potential senolytic drug for preventing GBM progression and improving RBI.

The Quest for Eternal Youth: Hallmarks of Aging and Rejuvenating Therapeutic Strategies

The impressive achievements made in the last century in extending the lifespan have led to a significant growth rate of elderly individuals in populations across the world and an exponential increase in the incidence of age-related conditions such as cardiovascular diseases, diabetes mellitus type 2, and neurodegenerative diseases. To date, geroscientists have identified 12 hallmarks of aging (genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, impaired macroautophagy, mitochondrial dysfunction, impaired nutrient sensing, cellular senescence, stem cell exhaustion, defective intercellular communication, chronic inflammation, and gut dysbiosis), intricately linked among each other, which can be targeted with senolytic or senomorphic drugs, as well as with more aggressive approaches such as cell-based therapies. To date, side effects seriously limit the use of these drugs. However, since rejuvenation is a dream of mankind, future research is expected to improve the tolerability of the available drugs and highlight novel strategies. In the meantime, the medical community, healthcare providers, and society should decide when to start these treatments and how to tailor them individually.

Therapeutic targeting of senescent cells in the CNS

Senescent cells accumulate throughout the body with advanced age, diseases and chronic conditions. They negatively impact health and function of multiple systems, including the central nervous system (CNS). Therapies that target senescent cells, broadly referred to as senotherapeutics, recently emerged as potentially important treatment strategies for the CNS. Promising therapeutic approaches involve clearing senescent cells by disarming their pro-survival pathways with 'senolytics'; or dampening their toxic senescence-associated secretory phenotype (SASP) using 'senomorphics'. Following the pioneering discovery of first-generation senolytics dasatinib and quercetin, dozens of additional therapies have been identified, and several promising targets are under investigation. Although potentially transformative, senotherapies are still in early stages and require thorough testing to ensure reliable target engagement, specificity, safety and efficacy. The limited brain penetrance and potential toxic side effects of CNS-acting senotherapeutics pose challenges for drug development and translation to the clinic. This Review assesses the potential impact of senotherapeutics for neurological conditions by summarizing preclinical evidence, innovative methods for target and biomarker identification, academic and industry drug development pipelines and progress in clinical trials.

Cellular senescence and its pathogenic and therapeutic implications in autoimmune hepatitis

INTRODUCTION

Senescent cells are characterized by replicative arrest and phenotypes that produce diverse pro-inflammatory and pro-oxidant mediators. The senescence of diverse hepatic cell types could constitute an unrecognized pathogenic mechanism and prognostic determinant in autoimmune hepatitis. The impact of cellular senescence in autoimmune hepatitis is unknown, and it may suggest adjunctive management strategies.

AREAS COVERED

This review describes the molecular mechanisms of cellular senescence, indicates its diagnostic features, suggests its consequences, presents possible therapeutic interventions, and encourages investigations of its pathogenic role and management in autoimmune hepatitis. Treatment prospects include elimination or reversal of senescent cells, generation of ectopic telomerase, reactivation of dormant telomerase, neutralization of specific pro-inflammatory secretory products, and mitigation of the effects of mitochondrial dysfunction.

EXPERT OPINION

The occurrence, nature, and consequences of cellular senescence in autoimmune hepatitis must be determined. The senescence of diverse hepatic cell types could affect the outcome of autoimmune hepatitis by impairing hepatic regeneration, intensifying liver inflammation, and worsening hepatic fibrosis. Cellular senescence could contribute to suboptimal responses during conventional glucocorticoid-based therapy. Interventions that target specific pro-inflammatory products of the senescent phenotype or selectively promote apoptosis of senescent cells may be preferred adjunctive treatments for autoimmune hepatitis depending on the cancer risk.

Senescent endothelial cells: a potential target for diabetic retinopathy

Diabetic retinopathy (DR) is a diabetic complication that results in visual impairment and relevant retinal diseases. Current therapeutic strategies on DR primarily focus on antiangiogenic therapies, which particularly target vascular endothelial growth factor and its related signaling transduction. However, these therapies still have limitations due to the intricate pathogenesis of DR. Emerging studies have shown that premature senescence of endothelial cells (ECs) in a hyperglycemic environment is involved in the disease process of DR and plays multiple roles at different stages. Moreover, these surprising discoveries have driven the development of senotherapeutics and strategies targeting senescent endothelial cells (SECs), which present challenging but promising prospects in DR treatment. In this review, we focus on the inducers and mechanisms of EC senescence in the pathogenesis of DR and summarize the current research advances in the development of senotherapeutics and strategies that target SECs for DR treatment. Herein, we highlight the role played by key factors at different stages of EC senescence, which will be critical for facilitating the development of future innovative treatment strategies that target the different stages of senescence in DR.

Targeting senescent cells in atherosclerosis: Pathways to novel therapies

Targeting senescent cells has recently emerged as a promising strategy for treating age-related diseases, such as atherosclerosis, which significantly contributes to global cardiovascular morbidity and mortality. This review elucidates the role of senescent cells in the development of atherosclerosis, including persistently damaging DNA, inducing oxidative stress and secreting pro-inflammatory factors known as the senescence-associated secretory phenotype. Therapeutic approaches targeting senescent cells to mitigate atherosclerosis are summarized in this review, which include the development of senotherapeutics and immunotherapies. These therapies are designed to either remove these cells or suppress their deleterious effects. These emerging therapies hold potential to decelerate or even alleviate the progression of AS, paving the way for new avenues in cardiovascular research and treatment.

Advantages and disadvantages of targeting senescent endothelial cells in cardiovascular and cerebrovascular diseases based on small extracellular vesicles

INTRODUCTION

With the growth of the aging population, age-related diseases have become a heavy global burden, particularly cardiovascular and cerebrovascular diseases (CVDs). Endothelial cell (EC) senescence constitutes an essential factor in the development of CVDs, prompting increased focus on strategies to alleviate or reverse EC senescence.

AREAS COVERED

Small extracellular vesicles (sEVs) are cell-derived membrane structures, that contain proteins, lipids, RNAs, metabolites, growth factors and cytokines. They are widely used in treating CVDs, and show remarkable therapeutic potential in alleviating age-related CVDs by inhibiting or reversing EC senescence. However, unclear anti-senescence mechanism poses challenges for clinical application of sEVs, and a systematic review is lacking.

EXPERT OPINION

Targeting senescent ECs with sEVs in age-related CVDs treatment represents a promising therapeutic strategy, with modifying sEVs and their contents emerging as a prevalent approach. Nevertheless, challenges remain, such as identifying and selectively targeting senescent cells, understanding the consequences of removing senescent ECs and senescence-associated secretory phenotype (SASP), and assessing the side effects of therapeutic sEVs on CVDs. More substantial experimental and clinical data are needed to advance clinical practice.

Senolytic treatment diminishes microglia and decreases severity of experimental autoimmune encephalomyelitis

BACKGROUND

The role of senescence in disease contexts is complex, however there is considerable evidence that depletion of senescent cells improves outcomes in a variety of contexts particularly related to aging, cognition, and neurodegeneration. Much research has shown previously that inflammation can promote cellular senescence. Microglia are a central nervous system innate immune cell that undergo senescence with aging and during neurodegeneration. The contribution of senescent microglia to multiple sclerosis, an inflammatory neurodegenerative disease, is not clear, but microglia are strongly implicated in chronic active lesion pathology, tissue injury, and disease progression. Drugs that could specifically eliminate dysregulated microglia in multiple sclerosis are therefore of great interest to the field.

RESULTS

A single-cell analysis of brain tissue from mice subjected to experimental autoimmune encephalomyelitis (EAE), a mouse model of CNS inflammation that models aspects of multiple sclerosis (MS), identified microglia with a strong transcriptional signature of senescence including the presence of BCL2-family gene transcripts. Microglia expressing Bcl2l1 had higher expression of pro-inflammatory and senescence associated genes than their Bcl2l1 negative counterparts in EAE, suggesting they may exacerbate inflammation. Notably, in human single-nucleus sequencing from MS, BCL2L1 positive microglia were enriched in lesions with active inflammatory pathology, and likewise demonstrated increased expression of immune genes suggesting they may be proinflammatory and contribute to disease processes in chronic active lesions. Employing a small molecule BCL2-family inhibitor, Navitoclax (ABT-263), significantly reduced the presence of microglia and macrophages in the EAE spinal cord, suggesting that these cells can be targeted by senolytic treatment. ABT-263 treatment had a profound effect on EAE mice: decreasing motor symptom severity, improving visual acuity, promoting neuronal survival, and decreasing white matter inflammation.

CONCLUSION

These results support the hypothesis that microglia and macrophages exhibit transcriptional features of cellular senescence in EAE and MS, and that microglia expressing Bcl2l1 demonstrate a proinflammatory signature that may exacerbate inflammation resulting in negative outcomes in neuroinflammatory disease. Depleting microglia and macrophages using a senolytic results in robust improvement in EAE disease severity, including across measures of neurodegeneration, inflammation, and demyelination, and may therefore represent a novel strategy to address disease progression in multiple sclerosis.

Molecular signaling and clinical implications in the human aging-cancer cycle

It is well documented that aging is associated with cancer, and likewise, cancer survivors display accelerated aging. As the number of aging individuals and cancer survivors continues to grow, it raises additional concerns across society. Therefore, unraveling the molecular mechanisms of aging in tissues is essential to developing effective therapies to fight the aging and cancer diseases in cancer survivors and cancer patients. Indeed, cellular senescence is a critical response, or a natural barrier to suppress the transition of normal cells into cancer cells, however, hypoxia which is physiologically required to maintain the stem cell niche, is increased by aging and inhibits senescence in tissues. Interestingly, oxygen restriction or hypoxia increases longevity and slows the aging process in humans, but hypoxia can also drive angiogenesis to facilitate cancer progression. In addition, cancer treatment is considered as one of the major reasons that drive cellular senescence, subsequently followed by accelerated aging. Several clinical trials have recently evaluated inhibitors to eliminate senescent cells. However, some mechanisms of aging typically can also retard cancer cell growth and progression, which might require careful strategy for better clinical outcomes. Here we describe the molecular regulation of aging and cancer in crosstalk with DNA damage and hypoxia signaling pathways in cancer patients and cancer survivors. We also update several therapeutic strategies that might be critical in reversing the cancer treatment-associated aging process.

Cellular Senescence and Anti-Aging Strategies in Aesthetic Medicine: A Bibliometric Analysis and Brief Review

Background

Skin aging is the most obvious feature of human aging, and delaying aging has become a hot and difficult research topic in aesthetic medicine. The accumulation of dysfunctional senescent cells is one of the important mechanisms of skin aging, based on which a series of anti-aging strategies have been generated. In this paper, from the perspective of cellular senescence, we utilize bibliometrics and research review to explore the research hotspots and trends in this field, with a view to providing references for skin health and aesthetic medicine.

Methods

We obtained literature related to this field from the Web of Science Core Collection database from 1994 to 2024. Bibliometrix packages in R, CiteSpace, VOSviewer, Origin, and Scimago Graphica were utilized for data mining and visualization.

Results

A total of 2,796 documents were included in the analysis. The overall trend of publications showed a continuous and rapid increase from 2016-2023, but the total citations improved poorly over time. In this field, Journal of Cosmetic Dermatology, Journal of Investigative Dermatology, Experimental Gerontology are core journals. Kim J, Lee JH, Lee S, Rattan SIS, Chung JH and Kim JH are the core authors in this field. Seoul National University is the first in terms of publications. Korea is the country with the most publications, but USA has the most total citations. Top 10 keywords include: gene-expression, skin, cellular senescence, cell, oxidative stress, antioxidants, in vitro, fibroblasts, mechanism, cancer. Current research trends are focused on neurodegeneration, skin rejuvenation, molecular docking, fibrosis, wound healing, SASP, skin barrier, and antioxidants. The core literature and references reflect topics such as the major molecular pathways in the aging process, and the relationship with tumors.

Conclusion

This field of research has been rapidly rising in recent years. Relevant research hotspots focus on oxidative stress, fibroblasts, and senescence-associated secretory phenotype. Anti-aging strategies targeting cellular senescence hold great promise, including removal of senescent cells or attenuation of SASP factors, corresponding to senolytics and senomorphics therapies, respectively.

Targeting senescent cells in aging and COVID-19: from cellular mechanisms to therapeutic opportunities

The COVID-19 pandemic has caused a global health crisis and significant social economic burden. While most individuals experience mild or non-specific symptoms, elderly individuals are at a higher risk of developing severe symptoms and life-threatening complications. Exploring the key factors associated with clinical severity highlights that key characteristics of aging, such as cellular senescence, immune dysregulation, metabolic alterations, and impaired regenerative potential, contribute to disruption of tissue homeostasis of the lung and worse clinical outcome. Senolytic and senomorphic drugs, which are anti-aging treatments designed to eliminate senescent cells or decrease the associated phenotypes, have shown promise in alleviating age-related dysfunctions and offer a novel approach to treating diseases that share certain aspects of underlying mechanisms with aging, including COVID-19. This review summarizes the current understanding of aging in COVID-19 progression, and highlights recent findings on anti-aging drugs that could be repurposed for COVID-19 treatment to complement existing therapies.

Emerging roles of senolytics/senomorphics in HIV-related co-morbidities

Human immunodeficiency virus (HIV) is known to cause cellular senescence and inflammation among infected individuals. While the traditional antiretroviral therapies (ART) have allowed the once fatal infection to be managed effectively, the quality of life of HIV patients on prolonged ART use is still inferior. Most of these individuals suffer from life-threatening comorbidities like chronic obstructive pulmonary disease (COPD), pulmonary arterial hypertension (PAH), and diabetes, to name a few. Interestingly, cellular senescence is known to play a critical role in the pathophysiology of these comorbidities as well. It is therefore important to understand the role of cellular senescence in the disease progression and co-morbidity development in HIV-infected individuals. In this respect, use of senolytic/senomorphic drugs as combination therapy with ART would be beneficial for HIV patients. This review provides a critical analysis of the current literature to determine the potential and efficacy of using senolytics/senotherapeutics in managing HIV infection, latency, and associated co-morbidities in humans. The various classes of senolytics have been studied in detail to focus on their potential to combat against HIV infections and associated pathologies with advancing age.

Tryptanthrin targets GSTP1 to induce senescence and increases the susceptibility to apoptosis by senolytics in liver cancer cells

Targeting senescence has emerged as a promising strategy for liver cancer treatment. However, the lack of a safe agent capable of inducing complete senescence and being combined with senolytics poses a limitation. Here, we screened a natural product library and identified tryptanthrin (TRYP) as a potent inducer of cellular senescence in liver cancer cells both in vitro and in vivo. Mechanistically, Glutathione S-transferase P1 (GSTP1), a key regulator for redox homeostasis, was identified as a target protein for TRYP-induced senescence. TRYP directly bound to GSTP1 and inhibited its enzymatic activity, mediating reactive oxygen species (ROS) accumulation, followed by DNA damage response (DDR), consequently contributing to initiating primary senescence. Furthermore, TRYP triggered DNA damage-dependent activation of NF-κB pathway, which evoked senescence-associated secretory phenotype (SASP), thereby leading to senescence reinforcement. Importantly, TRYP exposed the vulnerability of tumor cells and sensitized senescent cells to apoptosis induced by senolytic agent ABT263, a Bcl2 inhibitor. Taken together, our findings reveal that TRYP induces cellular senescence via GSTP1/ROS/DDR/NF-κB/SASP axis, providing a novel potential application in synergizing with senolytic therapy in liver cancer.

Cellular senescence: A novel therapeutic target for central nervous system diseases

The underlying mechanisms of diseases affecting the central nervous system (CNS) remain unclear, limiting the development of effective therapeutic strategies. Remarkably, cellular senescence, a biological phenomenon observed in cultured fibroblasts in vitro, is a crucial intrinsic mechanism that influences homeostasis of the brain microenvironment and contributes to the onset and progression of CNS diseases. Cellular senescence has been observed in disease models established in vitro and in vivo and in bodily fluids or tissue components from patients with CNS diseases. These findings highlight cellular senescence as a promising target for preventing and treating CNS diseases. Consequently, emerging novel therapies targeting senescent cells have exhibited promising therapeutic effects in preclinical and clinical studies on aging-related diseases. These innovative therapies can potentially delay brain cell loss and functional changes, improve the prognosis of CNS diseases, and provide alternative treatments for patients. In this study, we examined the relevant advancements in this field, particularly focusing on the targeting of senescent cells in the brain for the treatment of chronic neurodegenerative diseases (e.g., Alzheimer's disease, Parkinson's disease, and multiple sclerosis) and acute neurotraumatic insults (e.g., ischemic stroke, spinal cord injury, and traumatic brain injury).

Senolytic effect of triterpenoid complex from Ganoderma lucidum on adriamycin-induced senescent human hepatocellular carcinoma cells model in vitro and in vivo

Background

Ganoderma lucidum (G. lucidum) is a famous medicinal mushroom that has been reported to prevent and treat a variety of diseases. Different extractions from G. lucidum have been used to manage age-related diseases, including cancer. Nevertheless, the senolytic activity of G. lucidum against senescent cancer cells has not been investigated. Although cellular senescence causes tumor growth inhibition, senescent cells promote the growth of the neighboring tumor cells through paracrine effects. Therefore, the elimination of senescent cells is a new strategy for cancer treatment.

Methods

In this study, senescence was triggered in HCC cells by the chemotherapeutic agent Adriamycin (ADR), and subsequently, cells were treated with TC to assess its senolytic activity.

Results

We found for the first time that the triterpenoid complex (TC) from G. lucidum had senolytic effect, which could selectively eliminate adriamycin (ADR)-induced senescent cells (SCs) of hepatocellular carcinoma (HCC) cells via caspase-dependent and mitochondrial pathways-mediated apoptosis and reduce the levels of senescence markers, thereby inhibiting the progression of cancers caused by SCs. TC could block autophagy at the late stage in SCs, resulting in a significant activation of TC-induced apoptosis. Furthermore, TC inhibited the senescence-associated secretory phenotype (SASP) in SCs through the inhibition of NF-κB, TFEB, P38, ERK, and mTOR signaling pathways and reducing the number of SCs. Sequential administration of ADR and TC in vivo significantly reduced tumor growth and reversed the toxicity of ADR.

Conclusion

A triterpenoid complex isolated from G. lucidum may serve as a novel senolytic agent against SCs, and its combination with chemotherapeutic agents may enhance their antitumor efficacy.

Linked regulation of genome integrity and senescence-associated inflammation by p53

Genomic instability and inflammation are distinct hallmarks of aging, but the connection between them is poorly understood. Understanding their interrelationship will help unravel new mechanisms and therapeutic targets of aging and age-associated diseases. Here we report a novel mechanism directly linking genomic instability and inflammation in senescent cells through a mitochondria-regulated molecular circuit driven by p53 and cytoplasmic chromatin fragments (CCF). We show, through activation or inactivation of p53 by genetic and pharmacologic approaches, that p53 suppresses CCF accumulation and the downstream inflammatory senescence-associated secretory phenotype (SASP), without affecting cell cycle arrest. p53 activation suppressed CCF formation by promoting DNA repair, and this is reflected in maintenance of genomic integrity, particularly in subtelomeric regions, as shown by single cell genome resequencing. Activation of p53 in aged mice by pharmacological inhibition of MDM2 reversed signatures of aging, including age- and senescence-associated transcriptomic signatures of inflammation and age-associated accumulation of monocytes and macrophages in liver. Remarkably, mitochondria in senescent cells suppressed p53 activity by promoting CCF formation and thereby restricting ATM-dependent nuclear DNA damage signaling. These data provide evidence for a mitochondria-regulated p53 signaling circuit in senescent cells that controls DNA repair, genome integrity, and senescence- and age-associated inflammation. This pathway is immunomodulatory in mice and a potential target for healthy aging interventions by small molecules already shown to activate p53.

Age-associated changes in innate and adaptive immunity: role of the gut microbiota

Aging is generally regarded as an irreversible process, and its intricate relationship with the immune system has garnered significant attention due to its profound implications for the health and well-being of the aging population. As people age, a multitude of alterations occur within the immune system, affecting both innate and adaptive immunity. In the realm of innate immunity, aging brings about changes in the number and function of various immune cells, including neutrophils, monocytes, and macrophages. Additionally, certain immune pathways, like the cGAS-STING, become activated. These alterations can potentially result in telomere damage, the disruption of cytokine signaling, and impaired recognition of pathogens. The adaptive immune system, too, undergoes a myriad of changes as age advances. These include shifts in the number, frequency, subtype, and function of T cells and B cells. Furthermore, the human gut microbiota undergoes dynamic changes as a part of the aging process. Notably, the interplay between immune changes and gut microbiota highlights the gut's role in modulating immune responses and maintaining immune homeostasis. The gut microbiota of centenarians exhibits characteristics akin to those found in young individuals, setting it apart from the microbiota observed in typical elderly individuals. This review delves into the current understanding of how aging impacts the immune system and suggests potential strategies for reversing aging through interventions in immune factors.