Longevity Papers

Scientific discovery has long relied on human creativity, with computation limited to analysis. Here we report an AI-guided system, K-Dense, that accelerates hypothesis testing and delivers robust scientific discoveries. Trained on ARCHS4 (57,584 samples, 28 tissues, 1,039 cohorts, ages 1-114), the unified ensemble clock achieved R2 = 0.854 and MAE = 4.26 years, while uniquely providing calibrated confidence intervals. This self-aware design flags predictions made at transitional or extreme ages, where biological heterogeneity peaks, suggesting clinical utility for uncertainty itself. Development revealed stage-specific markers, including CDKN2A/p16 (senescence), AMPD3 (muscle wasting), MIR29B2CHG (progeroid traits), and SEPTIN3 (neurodegeneration resistance). Sliding-window analysis across 85 overlapping ranges uncovered wave-like shifts in gene importance, showing that transcriptomic aging signatures evolve continuously, not discretely. By transforming biological age assessment from static point estimates to calibrated predictions with explicit uncertainty, this approach establishes reliable and interpretable clocks. Beyond the clock itself, K-Dense demonstrates how guided AI can compress months of exploration into weeks, pointing toward a scalable framework for accelerated scientific discovery.

Peripheral nerve injuries (PNI) present a significant challenge, particularly in aging populations where Schwann cell dysfunction, reduced c-Jun expression, increased senescence, and impaired myelin clearance hinder regeneration. Targeted therapies aim to restore Schwann cell plasticity and improve nerve repair. These include gene therapy to upregulate c-Jun, senolytic agents to eliminate senescent Schwann cells, pharmacological activation of JNK, ferroptosis inhibition, and stem cell-based transplantation. Biomaterial advancements, such as nerve guidance conduits, extracellular matrix hydrogels, and 3D-printed scaffolds, provide structural and biochemical support. Despite these advances, clinical translation remains challenging due to patient heterogeneity, the need for personalized approaches, and regulatory considerations. Integrating multimodal strategies holds promise for optimizing peripheral nerve repair in aging individuals. Future research must refine these therapies to develop clinically viable solutions that enhance functional recovery and improve quality of life for patients with PNI.

Bioactive compounds from food-compatible medicinal herbs have shown promise as preventive agents against age-related neurodegenerative conditions, particularly Alzheimer's disease (AD). The present work aimed to find Lobetyolin as a new suppressor of Aβ aggregation and its interventions on abnormal metabolism in AD. Aβ-expressing Caenorhabditis elegans (strain CL4176) and wild-type worms were employed to evaluate paralysis onset, lifespan, cerebral Aβ deposition, and intracellular reactive oxygen species (ROS) after Lobetyolin administration. Untargeted ultra-high-performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) metabolomics coupled with RNA-seq transcriptomics was carried out to profile systemic metabolic and gene-expression changes. Differential metabolites and transcripts were subjected to Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Ontology (GO), and pathway-impact analyses; hub targets were prioritized by integrating enrichment scores with in-silico docking. Lobetyolin (12.5-50 µM) markedly protected C. elegans from Aβ-driven toxicity and oxidative stress. In CL2006 worms, β-amyloid deposits fell by 54.8 ± 9.4%, while paralysis in CL4176 was delayed by 20.9 ± 4.5%. Lifespan increased by up to 18.2% in CL4176 and 25.0% in wild-type N2 worms. Concomitantly, intracellular ROS declined maximally by 28.1 ± 8.9% (N2) and 22.4 ± 3.8% (CL4176). Integrative metabolomic-transcriptomic analyses, validated by RT-qPCR, revealed selective remodeling of glutathione metabolism: gst-38 expression was suppressed, whereas gst-1 was elevated. Lobetyolin confers neuroprotective and geroprotective benefits in vivo, primarily through reprogramming glutathione-centered redox metabolism and selectively modulating glutathione-S-transferases (GST) isoforms. These findings position Lobetyolin as a promising dietary lead compound for AD prevention and healthy aging interventions.

Exercise protects against age-related declines in skeletal muscle mass and function while improving overall health. Exercise can also prime long-term muscle health to enhance adaptations upon exercise retraining, a phenomenon termed muscle memory that remains largely understudied. To assess how prior endurance training elicits a lasting metabolic memory in skeletal muscle, we utilized C57BL/6 mice fed either a control (CD) or obesogenic diet (HFD) that underwent 4-week training, detraining, and retraining periods. Our results show that exercise retraining attenuated weight gain and potentiated muscle growth, even with reduced voluntary running volumes. Training increased fiber size (fCSA), which disappeared with detraining and was recovered with retraining regardless of diet, pointing to a glycolytic-to-oxidative fiber shift. Transcriptomic analysis (bulk RNA-seq) of the retrained muscle revealed a robust enhancement of mitochondrial oxidative phosphorylation (OxPhos) and mitoribosomal genes, paralleled by increases in OxPhos protein complex IV levels, higher long-chain fatty acid oxidative capacity (ACADL), and sustained citrate synthase activity 1 week after retraining, reinforcing the optimization of mitochondrial metabolism. While transcriptomic evidence revealed a major overlap between HFD- and CD-fed mice, discrepancies in protein abundance emerged, which point to an intricate regulation of mitochondrial programming that supports the muscle memory of growth. Our study identifies common and selective mechanisms by which the muscle memory of exercise overrides dietary challenges and promotes fiber hypertrophy, offering insight into potential mechanisms to leverage to promote healthy aging.

A multidimensional social exposome (MSE)-the combined lifespan measures of education, food insecurity, financial status, access to healthcare, childhood experiences, and more-may shape dementia risk and brain health over the lifespan, particularly in underserved regions like Latin America. However, the MSE effects on brain health and dementia are unknown. We evaluated 2211 individuals (controls, Alzheimer's disease, and frontotemporal lobar degeneration) from a non-representative sample across six Latin American countries. Adverse exposomes associate with poorer cognition in healthy aging. In dementia, more complex exposomes correlate with lower cognitive and functional performance, higher neuropsychiatric symptoms, and brain structural and connectivity alterations in frontal-temporal-limbic and cerebellar regions. Food insecurity, financial resources, subjective socioeconomic status, and access to healthcare emerge as critical predictors. Cumulative exposome measures surpass isolated factors in predicting clinical-cognitive profiles. Multiple sensitivity analyses confirm our results. Findings highlight the need for personalized approaches integrating MSE across the lifespan, emphasizing prevention and interventions targeting social disparities.

The environment experienced by children, such as exposure to chronic early life adversity (ELA), increases lifespan brain disorder risk. The mechanisms that link ELA exposure to functional brain disruptions are not well understood. A limited-bedding and nesting paradigm, in which ELA is induced in mouse pups over the first postnatal week through disruption of maternal care, is characterized by limited resources, environment unpredictability, and disruption of reward and cognitive behaviors. Studies using this model demonstrated sex-selective alterations in hippocampal mitochondrial-associated proteins in response to ELA compared to care as usual (CAU). Further, oxidative phosphorylation (OXPHOS) capacity and complex I activity are increased in ELA juveniles, yet decreased in adults, with the impact of ELA moderated by sex in female adults. Given that altered mitochondrial function is a key mediator in metabolic adaptations, the goal of the present study was to evaluate the possibility of reversing mitochondrial dysfunction and the anhedonia that accompanies ELA by addressing oxidative stress. Treatment with the antioxidant MitoQ began at weaning and extended to 3 months. Measures of complex I activity demonstrated full recovery in adults. Female-specific deficits in the sucrose preference task, which is a measure of rewarding behavior in rodents, also exhibited recovery, with preference for sucrose comparable to that of CAU mice. These data indicate that mitochondrial health is one component of responses to early life adversity that has lifespan implications, but with the capacity to recover normal functioning in adults.

Biological age is a major risk factor in the development of common degenerative retinal diseases such as age-related macular degeneration and glaucoma. To systematically characterize molecular mechanisms underlying retinal aging, we performed integrated single-cell RNA- and ATAC-Seq analyses of the retina and retinal pigment epithelium (RPE) across the natural lifespan in zebrafish, mice, and humans. By profiling gene expression and chromatin accessibility, we identified extensive cell type- and species-specific aging-dependent changes, with a much smaller number of broadly expressed and conserved genes that include regulators of inflammation and autophagy. We constructed predictive aging clocks for retinal cell types and observed dynamic, reversible shifts in cellular age following acute injury. Spatial transcriptomic analysis revealed region-specific aging signatures and proximity effects, with Muller glia exhibiting pro-rejuvenating influences on neighboring neurons. Targeted Muller glia-specific induction of Yamanaka factors reduced molecular age in rod photoreceptors and bipolar cells without altering glial age. Our findings define conserved and divergent regulatory and signaling pathways mediating retinal aging, highlighting Muller glia as potential therapeutic targets for combating age-associated retinal dystrophies.

Influenza A virus (IAV) infection causes significantly greater morbidity and mortality in the elderly population, but the molecular mechanisms in the aging process responsible for severe infection remain unclear. In this study, we found that increased severity in IAV infection and reduced innate immune response correlated with extensive mitophagy in senescent human cells and in the lung of aged mice. Apolipoprotein D (ApoD) was identified as strongly elevated in the lungs and sera of aged human (>65 y old) and mouse (>21 mo old). ApoD was able to localize to mitochondria and interact, through its WXXI motif in the LC3B-Interacting Region domain, with LC3B to trigger mitophagy during IAV infection, in a PINK1 pathway independent manner, which attenuated type I interferon response and promoted virus replication. ApoD deficiency, on the other hand, protected older mice from severe influenza and improved survival. Likewise, depletion of senescent cells by ABT-263, a senolytic compound, in aged mice lowered ApoD level and restored innate immune antiviral response, limiting virus propagation and associated pulmonary damage. Thus, age-induced ApoD drives IAV-mediated mitophagy, and promotes virus replication and infection severity, and is therefore a promising target for inhibition to improve disease outcome in older patients.

The mechanisms linking hearing ability, inflammation, glymphatic system function, and cognitive impairment in older adults are largely unknown. To investigate this issues, magnetic resonance imaging (MRI) was used to test for dysfunctions in the glymphatic system of older adults with hearing loss and to determine the relationship of glymphatic dysfunction, inflammation and cognitive deficits. This cross-sectional observational study included participants with ARHL and healthy controls (HCs) between January 2021 and December 2023. Participants underwent MRI scans of the glymphatic indices and clinical assessment of auditory, neuropsychological, and inflammatory measures. Multimodal MRI indices were used as proxies of glymphatic function and compared with measures of inflammation and cognition dysfunction in the older adults with hearing loss and control groups. Mann-Whitney U test, Spearman rank correlation and Mediation analysis were conducted. A total of 130 hearing loss patients (mean age years, 64.10 ± 3.43 [SD], 67 males) and 121 healthy controls (mean age years, 63.55 ± 3.49 [SD], 68 males) were included. The hearing loss group differed significantly from normal hearing control on MRI glymphatic measures of choroid plexus volume (CPV) (1.48 vs 1.37, p = 0.0004), enlarged perivascular spaces (EPVS) (1.74 vs 1.55, p < 0.0001) and diffusion tensor image analysis along the perivascular space (DTI-ALPS) (1.47 vs 1.63, p < 0.0001). Hearing loss severity was associated with higher values of CPV and EPVS and lower values of ALPS and strongly correlated with higher levels of inflammation (all FDR q < 0.05). Mediation analysis showed that ALPS and CPV mediate the relationship between hearing loss and scores on the Montreal Cognitive Assessment (MoCA) and Digit Symbol Substitution Test (DSST), respectively. Our findings support a potential associative pathway that inflammation and glymphatic dysfunction act as plausible intermediate factors facilitating the pathological relationship linking the increase in hearing loss in older adults to decline in cognition.

Due to the paucity of longitudinal DNA methylation data (DNAm), especially among Hispanic/Latino adults, the association between changes in epigenetic clocks over time and cognitive aging phenotypes has not been investigated. This longitudinal study included 2671 Hispanic/Latino adults (57 years; 66% women) with blood DNAm data and neurocognitive function assessed at two visits ~7 years apart. We evaluated the associations of 5 epigenetic clocks and their between-visit change with multiple measures of cognitive aging that included a global and domain-specific cognitive function score at each visit, between-visit change in global and domain-specific cognitive function score, and MCI diagnosis at visit 2 (V2). There were significant associations between greater acceleration of all clocks and lower cognitive function at each visit and MCI at V2. The strongest associations were observed for GrimAge and DunedinPACE. There were significant associations of between-visit increase in PhenoAge and GrimAge acceleration with decline in cognitive function and greater risk of MCI diagnosis at V2. Epigenetic aging is associated with lower global and domain-specific cognitive function, greater cognitive decline, and greater risk of MCI in Hispanic/Latino adults. Longitudinal assessment of change in age acceleration for second-generation clocks, GrimAge and PhenoAge may provide additional value in predicting cognitive aging beyond a single time point assessment.

In the past century, the human Lifespan has doubled. However, this is not equivalent to Healthspan which refers to the number of years spent healthy and free from disease. Women have an additional level of complexity on the path to optimal healthspan where health resilience dramatically decreases following menopause and this is due to their ovaries aging by midlife. It still remains elusive on why and how the ovaries in women, albeit their distinct and vital reproductive functions, start to age before any other organs. Following menopause, women are at increased risks of age-associated chronic diseases such as cardiometabolic disease, osteoporosis, sarcopenia, frailty, and neurocognitive decline. By preserving reproductive longevity through targeting the ovary as the organ to rejuvenate in women, optimal healthspan could be obtained in women. Interestingly, population studies have shown that women who conceive naturally and give birth at advanced reproductive ages are demonstrated to have superior postmenopausal longevity. Correspondingly, men Lived longer with a sister reproducing after 45 years of age in natural fertility conditions, suggesting that late female fertility and slow somatic aging may be promoted by the same genetic variants. Causal inference analysis showed a link between increased reproductive lifespan (prolonged ovarian lifespan or later age at natural menopause) and a reduction of diseases such as diabetes and osteoporosis. Essentially, fewer ovarian follicles and shorter ovarian lifespan were associated with poorer health later in life. Therefore, innovative ways to understand and target the ovaries in women for gero-protection have the potential to avert aging diseases triggered by the female menopause. Our narrative review aims to integrate existing information from systemic and reproductive aging from preclinical and human studies to devise novel methodologies to avert ovarian aging which could potentially improve the health trajectory in aging women. Similar strategies can be applied to men to achieve healthy longevity in the population. While there are certain things one has little control over, such as genetics and the inevitable reduction of reproductive hormone levels over time, there are modifiable risk factors which can be targeted to preserve reproductive longevity by uniquely targeting the ovary especially in modifying and improving the ovarian microenvironment to ensure survival of the ovarian follicles which determine true reproductive lifespan and healthspan. This can be achieved by modifying diet, sleep patterns, and exercise and limiting toxin exposure to ensure optimal ovarian health, through healthy and functional ovarian follicles, which could bring us a step closer to enhancing women's healthspan and human longevity.

Beyond their classical functions as redox cofactors, recent fundamental and clinical research has expanded our understanding of the diverse roles of nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) in signaling pathways, epigenetic regulation and energy homeostasis. Moreover, NAD and NADP influence numerous diseases as well as the processes of aging, and are emerging as targets for clinical intervention. Here, we summarize safety, bioavailability and efficacy data from NAD

The global rise in ageing populations is driving an increase in age-associated diseases, including haematological malignancies such as myelodysplastic syndromes and acute myeloid leukaemia. A major challenge in addressing this burden is the lack of experimental systems that enable mechanistic studies and therapeutic screening in ageing haematopoiesis. Here, we evaluate a polymer-based ex vivo culture platform for studying human haematopoietic stem and progenitor cells (HSPCs) in the context of ageing. Using CD34 cells from cord blood, bone marrow and peripheral blood from different age groups, we show that this culture system enables robust expansion of HSPCs while preserving age-associated transcriptional programs. Single-cell RNA sequencing revealed enrichment of key progenitor populations with consistent transcriptional identities across donors. Importantly, expanded HSPCs from older individuals retained ageing-associated signatures, such as upregulation of inflammatory pathways. These findings demonstrate that our polymer-based expansion system enables robust modelling of ageing haematopoiesis and provide a single cell transcriptional landscape of this ageing model. We envision that this system could provide a versatile platform for mechanistic studies and pharmacological testing, addressing a critical gap in experimental frameworks for age-related haematological disease research.

Peripheral sensory neurons regenerate their axons after injury to regain function, but this ability declines with age. The mechanisms behind this decline are not fully understood. While excessive production of endothelin 1 (ET-1), a potent vasoconstrictor, is linked to many diseases that increase with age, the role of ET-1 and its receptors in axon regeneration is unknown. Using single-cell RNA sequencing, we show that satellite glial cells (SGCs), which completely envelop the sensory neuron soma residing in the dorsal root ganglia (DRG), express the endothelin B receptor (ETBR), while ET-1 is expressed by endothelial cells. Inhibition of ETBR ex vivo in DRG explant cultures improves axon growth in both adult and aged conditions. In vivo, treatment with the FDA-approved compound, Bosentan, improves axon regeneration and reverses the age-dependent decrease in axonal regenerative capacity. Single-nuclei RNA sequencing and electron microscopy analyses reveal a decreased abundance of SGCs in aged mice compared to adult mice. Additionally, the decreased expression of connexin 43 (Cx43) in SGCs in aged mice after nerve injury is partially rescued by Bosentan treatment. These results reveal that inhibiting ETBR function enhances axon regeneration and rescues the age-dependent decrease in axonal regenerative capacity, providing a potential avenue for future therapies.

The Arctic ground squirrel (AGS, Urocitellus parryii), an extreme hibernator, exhibits remarkable resilience to stressors like hypoxia and hypothermia, making it an ideal model for studying cellular metabolic adaptation. The underlying mechanisms of AGS resilience are largely unknown. Here, we use lipidomic and metabolomic profiling to discover specific downregulation of triglyceride lipids and upregulation of the lipid biosynthetic precursor malonic acid in AGS neural stem cells (NSC) versus murine NSCs. Inhibiting lipid biosynthesis recapitulates hypoxic resilience of squirrel NSCs. Extending this model, we find that acute exposure to hypoxia downregulates key lipid biosynthetic enzymes in C. elegans, while inhibiting lipid biosynthesis reduces mitochondrial fission and facilitates hypoxic survival. Moreover, inhibiting lipid biosynthesis protects against APOE4-induced pathologies and aging trajectories in C. elegans. These findings suggest triglyceride downregulation as a conserved metabolic resilience mechanism, offering insights into protective strategies for neural tissues under hypoxic or ischemic conditions, APOE4-induced pathologies and aging.

Ashwagandha (Withania somnifera), a revered herb in Ayurvedic medicine, has gained significant scientific recognition for its potential to promote healthy aging. Traditionally used as a Rasayana or rejuvenator, this potent adaptogen helps the body manage stress and enhance vitality. This review synthesises extensive evidence for its multifaceted anti-aging capabilities, which target key hallmarks of the aging process. The mechanisms underpinning its effects include enhancing telomerase activity to support cellular longevity, combating systemic oxidative stress, and powerfully countering inflammaging by modulating immune responses and lowering inflammatory markers like C-reactive protein. Robust clinical evidence demonstrates its efficacy in improving crucial physiological parameters, including significant gains in muscle strength and size, enhanced cardiorespiratory fitness, hormonal balance, skin health, and improved sleep quality in older adults. Furthermore, trials have consistently shown its ability to improve cognitive function, including memory and information-processing speed, particularly in adults with mild cognitive impairment. Promising preclinical data also highlight its neuroprotective potential in models of Alzheimer's and Parkinson's disease. Here, we review the current evidence supports Ashwagandha's therapeutic potential in extending healthspan and enhancing quality of life. Large-scale, long-term clinical trials using standardized extracts are essential to fully confirm its role in healthy aging within the global population.

The CST (CTC1-STN1-TEN1) complex, a single-stranded DNA (ssDNA) binding complex, is essential for telomere maintenance and genome stability. Depletion of either CTC1 or STN1 results in cellular senescence, while mutations in these components are associated with severe hereditary disorders. In this study, we demonstrate that the direct STN1-CTC1 interaction stabilizes CTC1 by preventing its degradation via TRIM32 mediated ubiquitination. Functional assays indicate that TRIM32 and the CTC1/STN1 complex exert opposing effects on cellular proliferation. Additionally, transcriptomic analysis of large-scale RNA sequencing data from the Genotype-Tissue Expression (GTEx) reveals inverse expression patterns of TRIM32 and CTC1/STN1 during somatic cell aging. Structural modeling using AlphaFold3 predicts that the TRIM32-CTC1 interaction occurs at the OB-G domain of CTC1, with the binding interface positioned near the STN1-interacting region, termed the "cleft" motif. Mechanistically, STN1 likely associates with the OB-G domain of CTC1, competing with TRIM32 for binding sites and thereby interfering with TRIM32-mediated ubiquitination of CTC1. Collectively, our findings identify STN1 as a critical regulator of CST complex integrity and cellular aging by safeguarding CTC1 from TRIM32-driven ubiquitin-proteasome degradation.

Somatic mutations in several genes, including key oncogenes and tumour suppressor genes, are present from early life and can accumulate as an individual ages, indicating that the potential for cancer is present and growing throughout life. However, the risk of developing cancer rises sharply after 50-60 years of age, suggesting that the ability of these mutations to undergo clonal expansion and drive cancer development is dependent on the progressive changes in the epigenome and microenvironment that occur during ageing. Epigenetic changes, including DNA methylation and histone modifications, can drive various hallmarks of ageing in precancerous cells, including induction of senescence, the senescence-associated secretory phenotype, genomic instability and reduction of nuclear integrity, metabolic and inflammatory stress responses, stem cell function and differentiation potential, and redox balance. This can also alter the normal immune and stromal cells in the tissue microenvironment, which cumulatively enhances the effects of cancer driver mutations, ultimately promoting cancer development and progression in aged individuals. Unravelling these mechanisms will provide novel preventive and therapeutic strategies to limit the burden and progression of cancer in aged individuals.

The pace of organ ageing varies substantially between individuals, yet drivers of variability remain poorly understood. This gap is critical, given only 20-30% of longevity is genetically inherited and age-related diseases are leading causes of morbidity and mortality. Proteomic clocks allow organ ageing to be estimated from blood sampling, facilitating study of how life course exposures shape biological ageing heterogeneity. Here, we leverage the unique design of the MRC National Survey of Health and Development (NSHD), the world's oldest continuously followed birth cohort, to track 1,803 individuals across eight decades since birth in 1946. At mean age 63.2 years, we estimated proteomic ageing in seven organs. Despite near identical chronological ages, participants' proteomes revealed biological ageing disparities spanning decades. Extreme ageing in multiple organs was a strong prognostic indicator for all-cause mortality over the following 15 years (HR=6.62 for [≥]4 extremely aged organs). Adversity and being overweight in adolescence associated with accelerated ageing decades later in life. Completing secondary school education and maintaining physical activity linked to relative biological youth. Mediation analyses indicated liver, kidney and immune ageing linked life course exposures to mortality. Across 10,776 plasma protein targets, we identified 143 predictors of longevity, including MED9, strongly linked to diverse socio-behavioural exposures. These findings provide unique insights into which factors are likely to shape how we age, when in life they may be influential, and how biological effects emerge, informing healthy ageing promotion.

Hematopoietic stem cells (HSCs) responsible for blood cell production and their bone marrow regulatory niches undergo age-related changes, impacting immune responses and predisposing individuals to hematologic malignancies. Here, we show that the age-related alterations of the megakaryocytic niche and associated downregulation of Platelet Factor 4 (PF4) are pivotal mechanisms driving HSC aging. PF4-deficient mice display several phenotypes reminiscent of accelerated HSC aging, including lymphopenia, increased myeloid output, and DNA damage, mimicking physiologically aged HSCs. Remarkably, recombinant PF4 administration restored old HSCs to youthful functional phenotypes characterized by improved cell polarity, reduced DNA damage, enhanced in vivo reconstitution capacity, and balanced lineage output. Mechanistically, we identified LDLR and CXCR3 as the HSC receptors transmitting the PF4 signal, with double knockout mice showing exacerbated HSC aging phenotypes similar to PF4-deficient mice. Furthermore, human HSCs across various age groups also respond to the youthful PF4 signaling, highlighting its potential for rejuvenating aged hematopoietic systems. These findings pave the way for targeted therapies aimed at reversing age-related HSC decline with potential implications in the prevention or improvement of the course of age-related hematopoietic diseases.

Thymic function can decline due to age-related involution, congenital disorders, acute infections or chemo/radiation therapy. Decline in thymic function leads to decreased T cell production and weakened immunity. To address these thymic insufficiencies, we sought to develop a transplantable and scalable micro-organoid system using fibroblasts and thymic cells. We have developed a reliable and rapid method to generate thymic micro-organoids using selectively screened fibroblasts and murine thymic cells. The thymic micro-organoids are cryo-preservable, injectable, and give rise to T cells both in vitro and in vivo. Thymic organoids expressed key genes required to sustain T cell development and maturation: ccl25, dll-1, dll-4, foxn-1, il-7, scf. When injected into T cell-deficient Prkdcscid mice, the organoids gave rise to functional {beta}, {gamma}{delta}, natural killer T (NKT) cells, and FoxP3+ regulatory T cells. Organoid-derived T cells expressed a diverse T cell receptor (TCR) repertoire in vivo and respond to stimulation with anti-CD3/28, Concanavalin-A, or Phytohemagglutinin. Thymic organoids derived from pmel-1 thymocytes gave rise to V{beta}13+ T cells that delayed the growth of B16 melanoma and enhanced activation of T and NK cells. This approach presents a valuable tool for mechanistic studies and addressing current therapeutic gaps in diseases associated with thymic decline and insufficiencies.

Healthy protein homeostasis (\'proteostasis\') relies on tightly-regulated protein quality-control (PQC) circuits that co-ordinate sequestration and clearance of potentially toxic aggregation-prone proteins, arising from various internal or external stress throughout an organism\'s lifespan. At the protein level, proteotoxic stress responses typically involve extensive poly-ubiquitylation and sequestration of aggregation-prone proteins and PQC factors into various protective cytoplasmic and nuclear granules. However, much of our current understanding regarding this aspect of stress responses in humans stems from research in proliferating cells--despite growing evidence that stress responses vary considerably at the transcriptional level across cell proliferation states. Here, we show that the senescent cellular state--considered a major contributor to ageing-associated degeneration due to a chronic inflammatory phenotype--re-wires PQC and expels the misfolded protein load to mitigate proteotoxic stresses. Starting with a multi-dimensional transcriptomics and proteomics approach for measuring levels of total, poly-ubiquitylated, and granule-forming proteins, we have discovered a clear point of divergence between senescent and proliferating or quiescent human cell states in their responses to proteotoxic stress. Although the proteins that were poly-ubiquitylated and degraded during stress were largely conserved across states, the stress-induced sedimentation of a large number of disease-associated RNA-binding proteins (including TDP-43) was impaired only in the senescent state. Strikingly, TDP-43, as well as several other misfolded proteins, were actively secreted through the endo-lysosomal system by a diverse range of senescent cells during acute or chronic stress, through a process that requires the vesicle-associated HSP70 co-chaperone DNAJC5--an established risk factor for several neurodegenerative diseases. Misfolded protein secretion could be rescued by increasing intracellular HSP levels in \'shallow\' but not \'deep\' senescence, suggesting that secretion is a proteostatic adaptation that becomes less reversible over time. Our findings reveal an unappreciated aspect of the senescent-cell secretory phenotype, which may have important consequences for the non-cell-autonomous impact of senescence at the level of tissue resilience and frailty.

To investigate the functional significance of mitophagy in age-related osteogenic decline and the underlying mechanisms using in vivo and in vitro models.