Cellular Senescence: Mechanisms and Therapeutic Potential

Human platelet lysate produced from leukoreduction filter contents enables sufficient MSC growth

BACKGROUND

Stem cell therapy holds significant potential for promoting recovery, with numerous products currently under development. Blood-derived supplements are often essential for successful stem cell expansion, with fetal bovine serum (FBS) being the most commonly used supplement. However, FBS has drawbacks, including the risk of immune responses, ethical concerns about animal welfare, and potential zoonotic infections. Human platelet lysate (hPL), derived from lysed platelets, contains various growth factors and has been proposed as an alternative to FBS. However, obtaining sufficient human platelets for clinical use remains challenging. Leukoreduction filters, used during blood transfusion manufacturing to remove leukocytes, also retain significant amounts of platelets and plasma. This study investigates the feasibility and efficacy of filter-derived hPL (f-hPL) for mesenchymal stem cell (MSC) expansion.

METHODS

Leukoreduction filters were collected after their use in the manufacturing of whole blood transfusion products. Each filter was reverse-perfused with saline to extract residual blood contents. Platelets (f-platelet) and supernatant were separated by multiple centrifugation steps. f-Platelet were lysed with varying concentrations of fresh frozen plasma (FFP) to determine the optimal protein concentration for the lysate solution. Then, plasma left in the leukoreduction filters were used to generate lysate solution (f-plasma) at optimal protein concentration. f-Platelet (1.1 × 109/mL) and f-plasma (27 mg/mL protein) were combined in a freezing bag and subjected to three freeze-thaw cycles to produce f-hPL. Both small- and large-scale f-hPL were manufactured, and MSCs expansion and quality assessments were perfomed to evaluate the efficacy of f-hPL.

RESULTS

A total of 3.5 ± 0.6 × 1010 f-platelets were obtained from a single leukoreduction filter, yielding a collection efficiency of 37.1 ± 5.3%. The optimal protein concentration of lysate solution for cell expansion was > 27 mg/mL. Subsequently, six leukoreduction filters used to produce enough f-platelet and p-plasma for 100 mL of f-hPL. MSCs cultured in medium supplemented with 10% f-hPL demonstrated superior expansion, with cell proliferation rates 20% higher than those observed with commercial hPL and 300% higher than those cultured with FBS. The expanded MSCs met the International Society for Cell & Gene Therapy criteria for cell surface markers and differentiation potential. MSCs expanded with f-hPL expressed similar to or higher amounts of hepatocyte growth factor compared with those cultured with FBS and human AB serum. Furthermore, f-hPL significantly enhanced cell proliferation up to P12 and effectively prevented cell senescence.

CONCLUSION

f-hPL derived from leukoreduction filters demonstrated strong capacity for MSCs expansion. The use of discarded blood materials for regenerative medicine represents a sustainable and efficient approach, with significant therapeutic potential.

The Role of Aging and Senescence in Bone Marrow Transplantation Outcome

Bone marrow transplantation is considered a cornerstone in the treatment of hematologic malignancies and blood disorders. While it may offer the possibility of a cure through the use of high-dose chemotherapy and radiation, outcomes are significantly impacted by biological and medical factors. Herein, aging is associated with reduced hematopoiesis, immune function, and overall regenerative capacity of tissues. Growth arrest, a crucial property of cellular senescence, inhibits bone marrow function, lowers immune surveillance in aged adults, and reduces the efficiency of bone marrow transplantation. The clinical course for older recipients is further complicated by the presence of prolonged immunosuppression, slower recovery, and higher complication rates, including life-threatening graft-versus-host disease. Accordingly, there is increasing interest in explaining how aging, cellular senescence, and transplant outcomes are interrelated. The current chapter outlines the mechanisms whereby aging and senescence contribute to the immunological dysregulation and poor bone marrow transplantation outcomes observed in elderly cancer patients. The authors' goal is to suggest therapeutic approaches that will enhance the quality of life and survival rates of elderly bone marrow transplant recipients.

Simvastatin ameliorates senescence-induced mitochondrial dysfunction in vascular smooth muscle cells

BACKGROUND AND AIMS

Senescence and mitochondrial dysfunction are two major indicators of aging. Mitochondria are potential drivers of aging phenotypes and dysfunctional mitochondria are associated with several age-related diseases. There is evidence that senescence induces changes in mitochondrial structure, dynamics, and function. Moreover, senescent vascular smooth muscle cells (VSMCs) are present in atherosclerotic plaques and contribute to their instability. The anti-atherosclerotic effects of simvastatin are well known, but recently other benefits, such as promoting mitochondrial quality and senostatic effects, have been hypothesized. We aimed to analyze simvastatin's senostatic effects in senescent VSMCs.

METHODS

We established and characterized mitochondrial dysfunction in doxorubicin-induced senescent VSMCs (doxorubicin) or VSMCs serially passaged to induce replicative senescence (old).

RESULTS

We observed in both senescent models few typical senescence markers such as altered cell morphology, cell cycle inhibitors, laminB1, an accumulation of dysfunctional mitochondria characterized by reduced mitochondrial membrane potential (MMP) and respiration, accumulation of reactive oxygen species (ROS), and an altered mitochondria morphology. Down-regulation of TFAM and TOM70 expression was observed only in old cells suggesting a reduction of mitochondrial biogenesis. Next, we investigated whether simvastatin could ameliorate age-associated phenotypes in senescent VSMCs. Simvastatin 0.1 μM reduces the senescence-associated secretory phenotype (SASP) and ROS production and improves mitochondrial respiration in doxorubicin and old VSMCs. Interestingly, the effects of simvastatin on mitochondrial respiration and SASP were replicated by using a siRNA for the hydroxy-methyl-glutaryl-coenzyme A (HMG-CoA) reductase, and abolished by adding mevalonic acid, suggesting that these effects are mediated through the inhibition of HMG-CoA reductase.

CONCLUSIONS

Our results suggest that simvastatin controls SASP and exerts potentially beneficial therapeutic effects by ameliorating senescence-induced mitochondrial dysfunction in senescent VSMCs.

ALDH1A3 Regulates Cellular Senescence and Senescence-Associated Secretome in Prostate Cancer

Background: Radiotherapy is a key treatment for cancer, effectively controlling local tumor growth through DNA damage that induces senescence or apoptosis in cancer cells. However, radiotherapy can trigger complex cellular reactions, such as cell senescence, which is characterized by irreversible cell cycle arrest and the secretion of pro-inflammatory factors known as the senescent-associated secretory phenotype (SASP). Methods: This study investigates the regulatory role of ALDH1A3, a key enzyme implicated in cancer cell metabolism and radiotherapy resistance, in the induction of senescence and SASP. Using in vitro models, we demonstrate that ALDH1A3 knockdown accelerates cellular senescent-like phenotype while regulating the SASP through the cGAS-STING immune response pathway. Results: Our results indicate that while ALDH1A3 knockdown promotes senescence, it reduces the secretion of pro-inflammatory factors via inhibition of the cGAS-STING pathway, potentially mitigating SASP-related tumor progression. Conclusions: These findings provide insights into the molecular mechanisms underlying prostate cancer cell senescence and suggest that ALDH1A3 could be a potential therapeutic target to enhance the efficacy of radiotherapy while controlling the adverse effects of SASP.

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.

Nanodevice-Mediated Immune Cell Recruitment: Targeting Senescent Cells via MMP-3-Responsive CXCL12-Coated Nanoparticles

Senescent cells are involved in age-related disorders in different organs and are therapeutic targets for fibrotic and chronic pathologies. Immune-modulating agents, able to enhance senescent cell detection and elimination by endogenous immune cells, have emerged as pharmacological strategies. We report herein a nanoparticle for immune cell-mediated senolytic therapy designed to recruit immune cells in response to specific enzymatic matrix metalloproteinase-3 (MMP-3) activity in the senescence-associated secretory phenotype. For this, mesoporous silica nanoparticles (MSNs) are coated with a peptide substrate of the metalloproteinase MMP-3, and the peptide is decorated with chemokine CXCL12 that enhances immune cell recruitment (NPs@CXCL12). Controlled release studies confirmed the progressive and specific release of CXCL12 in the presence of MMP-3. The ability of immune cell recruitment in response to a senescent microenvironment (senescent WI-38 fibroblasts) is confirmed by Transwell migration assays with green fluorescent Jurkat T-cells, showing NPs@CXCL12 has an enhanced chemotaxis effect toward senescent cells compared to free CXCL12 (2-fold). Moreover, the cytotoxic capacity of human primary natural killer (NK) cells over senescent WI-38 is also confirmed, and their migration trajectories in response to NPs@CXCL12 or free CXCL12 are monitored by using a microfluidic device. Results confirm the ability of NPs@CXCL12 to generate a chemotactic gradient able to attract NK cells. When compared with free CXCL12, the NPs@CXCL12 system showed a reduction of up to 15.56% in the population of NK cells migrating toward free CXCL12 under competitive conditions. This study demonstrates the potential of designing nanoparticles to recruit immune cells under specific responses to eliminate senescent cells. Results confirm that NPs@CXCL12 can effectively establish a chemotactic gradient to attract NK cells.

A Narrative Review of Prognostic Gene Signatures in Oral Squamous Cell Carcinoma Using LASSO Cox Regression

Oral squamous cell carcinoma (OSCC) is one of the most common malignancies of the head and neck squamous cell carcinoma (HNSCC). HNSCC is recognized as the eighth most commonly occurring cancer globally in men. It is essential to distinguish between cancers arising in the head and neck regions due to significant differences in their etiologies, treatment approaches, and prognoses. As the Cancer Genome Atlas (TCGA) dataset is available in HNSCC, the survival analysis prognosis of OSCC patients based on the TCGA dataset for discovering gene expression-based prognostic biomarkers is limited. To address this paucity, we aimed to provide comprehensive evidence by recruiting studies that have reported new biomarkers/signatures to establish a prognostic model to predict the survival of OSCC patients. Using PubMed search, we have identified 34 studies that have been using the least absolute shrinkage and selection operator (LASSO)-based Cox regression analyses to establish signature prognosis that related to different pathways in OSCC from the past 4 years. Our review was focused on summarizing these signatures and implications for targeted therapy using FDA-approved drugs. Furthermore, we conducted an analysis of the LASSO Cox regression gene signatures. Our findings revealed 13 studies that correlated a greater number of regulatory T cells (Tregs) cells in protective gene signatures with increased recurrence-free and overall survival rates. Conversely, two studies displayed an opposing trend in cases of OSCC. We will also explore how the dysregulation of these signatures impacts immune status, promoting tumor immune evasion or, conversely, enhancing immune surveillance. Overall, this review will provide new insight for future anti-cancer therapies based on the potential gene that is associated with poor prognosis in OSCC.

New insights into methods to measure biological age: a literature review

Biological age is a concept that reflects the physiological state of an individual rather than the chronological time since birth. It can help assess the risk of age-related diseases and mortality and the effects of interventions to slow down or reverse aging. However, there is no consensus on measuring biological age best, and different methods may yield different results. In this paper, which includes 140 relevant pieces of literature, out of 33,000, we review some new methods to measure biological age based on recent advances in biotechnology and data science. We discussed some novel biomarkers and algorithms that can capture the dynamic and multidimensional aspects of aging at different levels. We evaluate their performance and validity using various datasets and criteria and compare them with existing methods. We also discuss their potential applications and implications for aging research and clinical practice. We conclude that the new methods offer more accurate and reliable estimates of biological age and open new avenues for understanding and modulating the aging process.

Role of astrocytes in Alzheimer's disease pathogenesis and the impact of exercise-induced remodeling

Alzheimer's disease (AD) is a prevalent and debilitating brain disorder that worsens progressively with age, characterized by cognitive decline and memory impairment. The accumulation of amyloid-beta (Aβ) leading to amyloid plaques and hyperphosphorylation of Tau, resulting in intracellular neurofibrillary tangles (NFTs), are primary pathological features of AD. Despite significant research investment and effort, therapies targeting Aβ and NFTs have proven limited in efficacy for treating or slowing AD progression. Consequently, there is a growing interest in non-invasive therapeutic strategies for AD prevention. Exercise, a low-cost and non-invasive intervention, has demonstrated promising neuroprotective potential in AD prevention. Astrocytes, among the most abundant glial cells in the brain, play essential roles in various physiological processes and are implicated in AD initiation and progression. Exercise delays pathological progression and mitigates cognitive dysfunction in AD by modulating astrocyte morphological and phenotypic changes and fostering crosstalk with other glial cells. This review aims to consolidate the current understanding of how exercise influences astrocyte dynamics in AD, with a focus on elucidating the molecular and cellular mechanisms underlying astrocyte remodeling. The review begins with an overview of the neuropathological changes observed in AD, followed by an examination of astrocyte dysfunction as a feature of the disease. Lastly, the review explores the potential therapeutic implications of exercise-induced astrocyte remodeling in the context of AD.

Can salivary and skin microbiome become a biodetector for aging-associated diseases? Current insights and future perspectives

Growth and aging are fundamental elements of human development. Aging is defined by a decrease in physiological activities and higher illness vulnerability. Affected by lifestyle, environmental, and hereditary elements, aging results in disorders including cardiovascular, musculoskeletal, and neurological diseases, which accounted for 16.1 million worldwide deaths in 2019. Stress-induced cellular senescence, caused by DNA damage, can reduce tissue regeneration and repair, promoting aging. The root cause of many age-related disorders is inflammation, encouraged by the senescence-associated secretory phenotype (SASP). Aging's metabolic changes and declining immune systems raise illness risk via promoting microbiome diversity. Stable, individual-specific skin and oral microbiomes are essential for both health and disease since dysbiosis is linked with periodontitis and eczema. Present from birth to death, the human microbiome, under the influence of diet and lifestyle, interacts symbiotically with the body. Poor dental health has been linked to Alzheimer's and Parkinson's diseases since oral microorganisms and systemic diseases have important interactions. Emphasizing the importance of microbiome health across the lifetime, this study reviews the understanding of the microbiome's role in aging-related diseases that can direct novel diagnosis and treatment approaches.

Inhibition of integrin binding to ligand arg-gly-asp motif induces AKT-mediated cellular senescence in hepatic stellate cells

BACKGROUND & AIMS

Hepatic stellate cells (HSCs) play an essential role in liver fibrogenesis. The induction of cellular senescence has been reported to inhibit HSC activation. Previously, we demonstrated that CWHM12, a small molecule arginine-glycine-aspartic acid (RGD) peptidomimetic compound, inhibits HSC activation. This study investigated whether the inhibitory effects of CWHM12 on HSCs affected cellular senescence.

METHODS

The immortalized human HSC lines, LX-2 and TWNT-1, were used to evaluate the effects of CWHM12 on cellular senescence via the disruption of RGD-mediated binding to integrins.

RESULTS

CWHM12 induces cell cycle arrest, senescence-associated beta-galactosidase activity, acquisition of senescence-associated secretory phenotype (SASP), and expression of senescence-associated proteins in HSCs. Further experiments revealed that the phosphorylation of AKT and murine double minute 2 (MDM2) was involved in the effects of CWHM12, and the inhibition of AKT phosphorylation reversed these effects of CWHM12 on HSCs.

CONCLUSIONS

Pharmacological inhibition of RGD-mediated integrin binding induces senescence in activated HSCs.

Glutaminase-1 inhibition alleviates senescence of Wharton's jelly-derived mesenchymal stem cells via senolysis

Replicative senescence of mesenchymal stem cells (MSCs) caused by repeated cell culture undermines their potential as a cell therapy because of the reduction in their proliferation and therapeutic potential. Glutaminase-1 (GLS1) is reported to be involved in the survival of senescent cells, and inhibition of GLS1 alleviates age-related dysfunction via senescent cell removal. In the present study, we attempted to elucidate the association between MSC senescence and GLS1. We conducted in vitro and in vivo experiments to analyze the effect of GLS1 inhibition on senolysis and the therapeutic effects of MSCs. Inhibition of GLS1 in Wharton's jelly-derived MSCs (WJ-MSCs) reduced the expression of aging-related markers, such as p16, p21, and senescence-associated secretory phenotype genes, by senolysis. Replicative senescence-alleviated WJ-MSCs, which recovered after short-term treatment with bis-2-(5-phenylacetamido-1,2,4-thiadiazol-2-yl)ethyl sulfide 3 (BPTES), showed increased proliferation and therapeutic effects compared to those observed with senescent WJ-MSCs. Moreover, compared to senescent WJ-MSCs, replicative senescence-alleviated WJ-MSCs inhibited apoptosis in serum-starved C2C12 cells, enhanced muscle formation, and hindered apoptosis and fibrosis in mdx mice. These results imply that GLS1 inhibition can ameliorate the therapeutic effects of senescent WJ-MSCs in patients with muscle diseases such as Duchenne muscular dystrophy. In conclusion, GLS1 is a key factor in modulating the senescence mechanism of MSCs, and regulation of GLS1 may enhance the therapeutic effects of senescent MSCs, thereby increasing the success rate of clinical trials involving MSCs.

Interplay Between Skeletal and Hematopoietic Cells in the Bone Marrow Microenvironment in Homeostasis and Aging

PURPOSE OF THE REVIEW

In this review, we discuss the most recent scientific advances on the reciprocal regulatory interactions between the skeletal and hematopoietic stem cell niche, focusing on immunomodulation and its interplay with the cell's mitochondrial function, and how this impacts osteoimmune health during aging and disease.

RECENT FINDINGS

Osteoimmunology investigates interactions between cells that make up the skeletal stem cell niche and immune system. Much work has investigated the complexity of the bone marrow microenvironment with respect to the skeletal and hematopoietic stem cells that regulate skeletal formation and immune health respectively. It has now become clear that these cellular components cooperate to maintain homeostasis and that dysfunction in their interaction can lead to aging and disease. Having a deeper, mechanistic appreciation for osteoimmune regulation will lead to better research perspective and therapeutics with the potential to improve the aging process, skeletal and hematologic regeneration, and disease targeting.

Mitochondrial dysfunction and its association with age-related disorders

Aging is a complex process that features a functional decline in many organelles. Various factors influence the aging process, such as chromosomal abnormalities, epigenetic changes, telomere shortening, oxidative stress, and mitochondrial dysfunction. Mitochondrial dysfunction significantly impacts aging because mitochondria regulate cellular energy, oxidative balance, and calcium levels. Mitochondrial integrity is maintained by mitophagy, which helps maintain cellular homeostasis, prevents ROS production, and protects against mtDNA damage. However, increased calcium uptake and oxidative stress can disrupt mitochondrial membrane potential and permeability, leading to the apoptotic cascade. This disruption causes increased production of free radicals, leading to oxidative modification and accumulation of mitochondrial DNA mutations, which contribute to cellular dysfunction and aging. Mitochondrial dysfunction, resulting from structural and functional changes, is linked to age-related degenerative diseases. This review focuses on mitochondrial dysfunction, its implications in aging and age-related disorders, and potential anti-aging strategies through targeting mitochondrial dysfunction.

Cellular Aging and Senescence in Cancer: A Holistic Review of Cellular Fate Determinants

This comprehensive review navigates the complex relationship between cellular aging, senescence, and cancer, unraveling the determinants of cellular fate. Beginning with an overview of cellular aging's significance in cancer, the review explores processes, changes, and molecular pathways influencing senescence. The review explores senescence as a dual mechanism in cancer, acting as a suppressor and contributor, focusing on its impact on therapy response. This review highlights opportunities for cancer therapies that target cellular senescence. The review further examines the senescence-associated secretory phenotype and strategies to modulate cellular aging to influence tumor behavior. Additionally, the review highlights the mechanisms of senescence escape in aging and cancer cells, emphasizing their impact on cancer prognosis and resistance to therapy. The article addresses current advances, unexplored aspects, and future perspectives in understanding cellular aging and senescence in cancer.

Retinoic acid receptor activation reprograms senescence response and enhances anti-tumor activity of natural killer cells

Cellular senescence can exert dual effects in tumors, either suppressing or promoting tumor progression. The senescence-associated secretory phenotype (SASP), released by senescent cells, plays a crucial role in this dichotomy. Consequently, the clinical challenge lies in developing therapies that safely enhance senescence in cancer, favoring tumor-suppressive SASP factors over tumor-promoting ones. Here, we identify the retinoic-acid-receptor (RAR) agonist adapalene as an effective pro-senescence compound in prostate cancer (PCa). Reactivation of RARs triggers a robust senescence response and a tumor-suppressive SASP. In preclinical mouse models of PCa, the combination of adapalene and docetaxel promotes a tumor-suppressive SASP that enhances natural killer (NK) cell-mediated tumor clearance more effectively than either agent alone. This approach increases the efficacy of the allogenic infusion of human NK cells in mice injected with human PCa cells, suggesting an alternative therapeutic strategy to stimulate the anti-tumor immune response in "immunologically cold" tumors.

Senescent-like macrophages mediate angiogenesis for endplate sclerosis via IL-10 secretion in male mice

Endplate sclerosis is a notable aspect of spine degeneration or aging, but the mechanisms remain unclear. Here, we report that senescent macrophages accumulate in the sclerotic endplates of lumbar spine instability (LSI) or aging male mouse model. Specifically, knockout of cdkn2a (p16) in macrophages abrogates LSI or aging-induced angiogenesis and sclerosis in the endplates. Furthermore, both in vivo and in vitro studies indicate that IL-10 is the primary elevated cytokine of senescence-related secretory phenotype (SASP). Mechanistically, IL-10 increases pSTAT3 in endothelial cells, leading to pSTAT3 directly binding to the promoters of Vegfa, Mmp2, and Pdgfb to encourage their production, resulting in angiogenesis. This study provides information on understanding the link between immune senescence and endplate sclerosis, which might be useful for therapeutic approaches.

Molecular hallmarks of ageing in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal, severely debilitating and rapidly progressing disorder affecting motor neurons in the brain, brainstem, and spinal cord. Unfortunately, there are few effective treatments, thus there remains a critical need to find novel interventions that can mitigate against its effects. Whilst the aetiology of ALS remains unclear, ageing is the major risk factor. Ageing is a slowly progressive process marked by functional decline of an organism over its lifespan. However, it remains unclear how ageing promotes the risk of ALS. At the molecular and cellular level there are specific hallmarks characteristic of normal ageing. These hallmarks are highly inter-related and overlap significantly with each other. Moreover, whilst ageing is a normal process, there are striking similarities at the molecular level between these factors and neurodegeneration in ALS. Nine ageing hallmarks were originally proposed: genomic instability, loss of telomeres, senescence, epigenetic modifications, dysregulated nutrient sensing, loss of proteostasis, mitochondrial dysfunction, stem cell exhaustion, and altered inter-cellular communication. However, these were recently (2023) expanded to include dysregulation of autophagy, inflammation and dysbiosis. Hence, given the latest updates to these hallmarks, and their close association to disease processes in ALS, a new examination of their relationship to pathophysiology is warranted. In this review, we describe possible mechanisms by which normal ageing impacts on neurodegenerative mechanisms implicated in ALS, and new therapeutic interventions that may arise from this.

Nervonic Acid Inhibits Replicative Senescence of Human Wharton's Jelly-Derived Mesenchymal Stem Cells

Cellular senescence causes cell cycle arrest and promotes permanent cessation of proliferation. Since the senescence of mesenchymal stem cells (MSCs) reduces proliferation and multipotency and increases immunogenicity, aged MSCs are not suitable for cell therapy. Therefore, it is important to inhibit cellular senescence in MSCs. It has recently been reported that metabolites can control aging diseases. Therefore, we aimed to identify novel metabolites that regulate the replicative senescence in MSCs. Using a fecal metabolites library, we identified nervonic acid (NA) as a candidate metabolite for replicative senescence regulation. In replicative senescent MSCs, NA reduced senescence-associated β-galactosidase positive cells, the expression of senescence-related genes, as well as increased stemness and adipogenesis. Moreover, in non-senescent MSCs, NA treatment delayed senescence caused by sequential subculture and promoted proliferation. We confirmed, for the first time, that NA delayed and inhibited cellular senescence. Considering optimal concentration, duration, and timing of drug treatment, NA is a novel potential metabolite that can be used in the development of technologies that regulate cellular senescence.

Targeted elimination of senescent cells by engineered extracellular vesicles attenuates atherosclerosis in ApoE-/- mice with minimal side effects

Senescent cells in plaques emerge as a detrimental factor for atherosclerosis (AS), for which targeted senolysis might be a promising therapeutic strategy. The development of safe and efficient senolytics for senescent cell eradication by targeted delivery is greatly needed. Methods: Pro-apoptotic intelligent Bax (iBax)-overexpressing plasmid was constructed by molecular cloning, in which Bax CDS was fused to miR-122 recognition sites. Extracellular vesicle-based senolytics (EViTx) were developed to be conjugated with magnetic nanoparticles on the surface, iBax mRNA encapsulated inside, and BAX activator BTSA1 incorporated into the membrane. EViTx was characterized, and in vivo distribution was tracked via fluorescence imaging. The therapeutic effects of EViTx on AS and its systemic side effects were analyzed in ApoE-/- mice. Results: Magnetic nanoparticles, iBax mRNA and BAX activator BTSA1 were efficiently loaded into/onto EViTx. With external magnetic field navigation, EViTx was delivered into atherosclerotic plaques and induced significant apoptosis in senescent cells regardless of origins. Repeated delivery of EViTx via tail vein injection has achieved high therapeutic efficacy in ApoE-/- mice. Notably, EViTx is inevitably accumulated in liver cells, while the iBax mRNA was translationally repressed by miR-122, an endogenous miRNA highly expressed in hepatocytes, and thus the liver cells are protected from the potential toxicity of Bax mRNA. Conclusion: Our work demonstrated that magnetic EV-based delivery of iBax mRNA and the BAX activator BTSA1, efficiently induced apoptosis in recipient senescent cells in atherosclerotic plaques. This strategy represents a promising treatment approach for AS and other age-related diseases.

mRNA vaccine in cancer therapy: Current advance and future outlook

Messenger ribonucleic acid (mRNA) vaccines are a relatively new class of vaccines that have shown great promise in the immunotherapy of a wide variety of infectious diseases and cancer. In the past 2 years, SARS-CoV-2 mRNA vaccines have contributed tremendously against SARS-CoV2, which has prompted the arrival of the mRNA vaccine research boom, especially in the research of cancer vaccines. Compared with conventional cancer vaccines, mRNA vaccines have significant advantages, including efficient production of protective immune responses, relatively low side effects and lower cost of acquisition. In this review, we elaborated on the development of cancer vaccines and mRNA cancer vaccines, as well as the potential biological mechanisms of mRNA cancer vaccines and the latest progress in various tumour treatments, and discussed the challenges and future directions for the field.

Genetic Deletion of FXR1 Reduces Intimal Hyperplasia and Induces Senescence in Vascular Smooth Muscle Cells

Vascular smooth muscle cells (VSMC) play a critical role in the development and pathogenesis of intimal hyperplasia indicative of restenosis and other vascular diseases. Fragile-X related protein-1 (FXR1) is a muscle-enhanced RNA binding protein whose expression is increased in injured arteries. Previous studies suggest that FXR1 negatively regulates inflammation, but its causality in vascular disease is unknown. In the current study, RNA-sequencing of FXR1-depleted VSMC identified many transcripts with decreased abundance, most of which were associated with proliferation and cell division. mRNA abundance and stability of a number of these transcripts were decreased in FXR1-depleted hVSMC, as was proliferation (P < 0.05); however, increases in beta-galactosidase (P < 0.05) and γH2AX (P < 0.01), indicative of senescence, were noted. Further analysis showed increased abundance of senescence-associated genes with FXR1 depletion. A novel SMC-specific conditional knockout mouse (FXR1SMC/SMC) was developed for further analysis. In a carotid artery ligation model of intimal hyperplasia, FXR1SMC/SMC mice had significantly reduced neointima formation (P < 0.001) after ligation, as well as increases in senescence drivers p16, p21, and p53 compared with several controls. These results suggest that in addition to destabilization of inflammatory transcripts, FXR1 stabilized cell cycle-related genes in VSMC, and absence of FXR1 led to induction of a senescent phenotype, supporting the hypothesis that FXR1 may mediate vascular disease by regulating stability of proliferative mRNA in VSMC.

Cellular senescence in aging: Molecular basis, implications and therapeutic interventions

Cellular senescence is an irreversible proliferation arrest in response to cellular damage and stress. Although cellular senescence is a highly stable cell cycle arrest, it can influence many physiological, pathological, and aging processes. Cellular senescence can be triggered by various intrinsic and extrinsic stimuli such as oxidative stress, mitochondrial dysfunction, genotoxic stress, oncogenic activation, irradiation and chemotherapeutic agents. Senescence is associated with several molecular and phenotypic alterations, such as senescence-associated secretory phenotype (SASP), cell cycle arrest, DNA damage response (DDR), senescence-associated β-galactosidase, morphogenesis, and chromatin remodeling. Cellular senescence is a regular physiological event involved in tissue homeostasis, embryonic development, tissue remodeling, wound healing, and inhibition of tumor progression. Mitochondria are one of the organelles that undergo significant morphological and metabolic changes associated with senescence. Recent evidence unraveled that inter-organelle communication regulates cellular senescence, where mitochondria form a highly complex and dynamic network throughout the cytoplasm with other organelles, like the endoplasmic reticulum. An imbalance in organelle interactions may result in faulty cellular homeostasis, which contributes to cellular senescence and is associated with organ aging. Since mitochondrial dysfunction is a common characteristic of cellular senescence and age-related diseases, mitochondria-targeted senolytic or redox modulator senomorphic strategies help solve the complex problems with the detrimental consequences of cellular senescence. Understanding the regulation of mitochondrial metabolism would provide knowledge on effective therapeutic interventions for aging and age-related pathologies. This chapter focuses on the biochemical and molecular mechanisms of senescence and targeting senescence as a potential strategy to alleviate age-related pathologies and support healthy aging.

Advances in cellular senescence in idiopathic pulmonary fibrosis (Review)

Idiopathic pulmonary fibrosis (IPF) is a progressive, irreversible and fatal interstitial lung disease of unknown cause, with a median survival of 2-3 years. Its pathogenesis is unclear and there is currently no effective treatment for IPF. Approximately two-thirds of patients with IPF are >60 years old, with a mean age of 66 years, suggesting a link between aging and IPF. However, the mechanism by which aging promotes development of PF remains unclear. Senescence of alveolar epithelial cells and lung fibroblasts (LFs) and their senescence-associated secretion phenotype (SASP) may be involved in the occurrence and development of IPF. The present review focus on senescence of LFs and epithelial and stem cells, as well as SASP, the activation of profibrotic signaling pathways and potential treatments for pathogenesis of IPF.

Involvement of inflammatory responses in the brain to the onset of major depressive disorder due to stress exposure

Major depressive disorder (MDD) is a multifactorial disease affected by several environmental factors. Although several potential onset hypotheses have been identified, the molecular mechanisms underlying the pathogenesis of this disorder remain unclear. Several recent studies have suggested that among many environmental factors, inflammation and immune abnormalities in the brain or the peripheral tissues are associated with the onset of MDDs. Furthermore, several stress-related hypotheses have been proposed to explain the onset of MDDs. Thus, inflammation or immune abnormalities can be considered stress responses that occur within the brain or other tissues and are regarded as one of the mechanisms underlying the stress hypothesis of MDDs. Therefore, we introduce several current advances in inflammation studies in the brain that might be related to the pathophysiology of MDD due to stress exposure in this review.

Interleukin-13 promotes cellular senescence through inducing mitochondrial dysfunction in IgG4-related sialadenitis

Immunoglobulin G4-related sialadenitis (IgG4-RS) is an immune-mediated fibro-inflammatory disease and the pathogenesis is still not fully understood. The aim of this study was to explore the role and mechanism of interleukin-13 (IL-13) in the cellular senescence during the progress of IgG4-RS. We found that the expression of IL-13 and IL-13 receptor α1 (IL-13Rα1) as well as the number of senescent cells were significantly higher in the submandibular glands (SMGs) of IgG4-RS patients. IL-13 directly induced senescence as shown by the elevated activity of senescence-associated β-galactosidase (SA-β-gal), the decreased cell proliferation, and the upregulation of senescence markers (p53 and p16) and senescence-associated secretory phenotype (SASP) factors (IL-1β and IL-6) in SMG-C6 cells. Mechanistically, IL-13 increased the level of phosphorylated signal transducer and activator of transcription 6 (p-STAT6) and mitochondrial-reactive oxygen species (mtROS), while decreased the mitochondrial membrane potential, ATP level, and the expression and activity of superoxide dismutase 2 (SOD2). Notably, the IL-13-induced cellular senescence and mitochondrial dysfunction could be inhibited by pretreatment with either STAT6 inhibitor AS1517499 or mitochondria-targeted ROS scavenger MitoTEMPO. Moreover, IL-13 increased the interaction between p-STAT6 and cAMP-response element binding protein (CREB)-binding protein (CBP) and decreased the transcriptional activity of CREB on SOD2. Taken together, our findings revealed a critical role of IL-13 in the induction of salivary gland epithelial cell senescence through the elevated mitochondrial oxidative stress in a STAT6–CREB–SOD2-dependent pathway in IgG4-RS.

Chrysin and Capsaicin Induces Premature Senescence and Apoptosis via Mitochondrial dysfunction and p53 elevation in Cervical Cancer cells

Current studies are focusing on the anti-cancerous properties of natural bioactive compounds, primarily those included in the human diet. These compounds have the potential to alter the redox balance that can hinder cancer cell's growth. In cancer cells, an abnormal rate of ROS production is balanced with higher antioxidant activities, which if not maintained, results in cancer cells being prone to cell death due to oxidative stress. Here, we have analyzed the effects of Chrysin and Capsaicin on the HeLa cells viability and cellular redox signaling. Both these compounds stimulate cellular and mitochondrial ROS overproduction that perturbs the cellular redox state and results in mitochondrial membrane potential loss. Apart from this, these compounds induce cell cycle arrest and induce premature senescence, along with the overexpression of p21, p53, and p16 protein at lower concentration treatment of Chrysin or Capsaicin. Moreover, at higher concentration treatment with these compounds, pro-apoptotic activity was observed with the high level of Bax and cleaved caspase-3 along with suppression of the Bcl-2 protein levels. In-Silico analysis with STITCH v5 also confirms the direct interaction of Chrysin and Capsaicin with target protein p53. This suggests that Chrysin and Capsaicin trigger an increase in mitochondrial ROS, and p53 interaction leading to premature senescence and apoptosis in concentration dependent manner and have therapeutic potential for cancer treatment.