Simon Melov

The human ovary is among the first organs to show age‐related functional decline, resulting in menopause. Beyond this transition, the postmenopausal ovary is often regarded as quiescent and remains poorly characterized. We analyzed the proteomes of healthy, non‐pathological ovaries using mass spectrometry (data‐independent acquisition) from 28 postmenopausal women (50–75 years old), stratified into three age groups (50–59, 60–69, ≥ 70). We quantified 5812 protein groups and observed progressive age‐associated shifts, with 117 proteins significantly altered in the ≥ 70 versus 50–59 age comparison. Multivariate analysis demonstrated clear separation between 50–59 and ≥ 70‐year‐old age cohorts, with protein signatures shifting from RNA/gene‐regulatory functions in younger ovaries to metabolic, trafficking, and innate immune/complement pathways in older ovaries. Across differential abundance, multivariate modeling, and covariate‐adjusted linear modeling, we identified a convergent set of age‐associated proteins that were integrated into the 26‐protein B uck P ostmenopausal O vary M olecular S ignature (BuckPOMS), a consensus molecular signature capturing progressive extracellular matrix remodeling, inflammatory signaling, and loss of structural and keratin‐associated proteins with age. Representative BuckPOMS proteins, including the secreted matrisome proteins WNT4 and Fibromodulin (FMOD), were validated by immunohistochemistry. Pathway enrichment further identified an increase in inflammatory and matrisome pathways, and increased abundance of damage‐associated secretory factors decades following menopause. These data fundamentally shift the notion of the postmenopausal ovary as an inert organ and instead demonstrate active and continuous molecular remodeling that has potential relevance to tissue signaling and implications for women's health.

Cellular senescence was initially defined in vitro as a stable cell-cycle arrest that occurs after repeated replication, but it is now recognized as a heterogeneous state shaped by cell type, species, senescence-inducing stress, tissue microenvironment and time. To organize this complexity, we propose the term ‘senotype’ to classify senescent cells by their inputs, molecular features and functional effects. We outline a practical framework incorporating: (1) cell identity and context; (2) inducing mechanism; (3) temporal stage; (4) multimodal molecular and structural features; and (5) physiological or pathological functions. Experimentally defined senotypes can serve as references for interpreting tissue-derived senotypes, where parameters may be incomplete. Senotypes should be anchored in combinations of core hallmarks (that is, durable cell-cycle arrest, altered secretory profiles, macromolecular or organelle damage, disrupted homeostasis) rather than single markers. Advances in single-cell, spatial, proteomic and computational methods enable rigorous senotype characterization, improving consistency and accelerating development of targeted senotherapeutics.

Brain white matter undergoes structural and functional alterations linked to late-life cognitive decline, but the cellular and molecular basis of its selective vulnerability remains incompletely defined. Here, in naturally aged mice, we demonstrate that senescent and disease-associated microglia (DAM) phenotypes converge in hippocampal-adjacent white matter, particularly in the fimbria. Using regional gene expression profiling, immunolabeling, GeoMx digital spatial profiling and CosMx spatial molecular imaging, we identify an aged brain-exclusive microglial population concentrated in white matter that expresses DAM genes together with a ‘SenBrain’ senescence gene signature, including galectin-3 (GAL3/Lgals3). Single-cell spatial trajectory analyses suggest that multiple cell fate transitions may give rise to this aged, proinflammatory, senescent- and DAM-linked state. Pharmacogenetic or pharmacological senotherapeutic interventions reduced white matter GAL3⁺ DAM abundance and restored a more youthful microglial organization in aged fimbria. These findings identify a senescence- and DAM-enriched microglial state as a prominent and partially reversible feature of aged brain white matter.

Acoustic droplet ejection (ADE) enables nanoliter-scale liquid handling for complex microplate assays, yet translating experimental designs into validated, instrument-ready instructions remains a bottleneck. We present PickliPy, an open-source framework that converts spreadsheet-based assay designs into validated ADE picklists. PickliPy.Assay supports combinatorial, dose-response, and multi-addition time-course dispensing, while PickliPy.Screen extends to high-throughput workflows, including library reformatting and shortlisting. Across biological contexts, the framework generated reproducible, assay-ready plates and standardized execution in human cohort studies. Acoustic pre-dispensing deepened bioenergetic phenotyping of human skeletal muscle mitochondria, capturing substrate switching and sharpened dose-response precision in human pancreatic β-cells, revealing an age-associated change in succinate dehydrogenase kinetics. We benchmarked a wash-free, live-cell screen of mitochondrial function and morphology, in which deep-learning image analysis widened the assay window, and ADE enabled integrative dose-response co-response analysis. These tools, including their agentic use, make complex ADE experiments easier to design and scale from single benches to screening campaigns.

Cardiomyopathy is clinically associated with female infertility, yet whether the failing heart directly suppresses reproduction has remained unknown. Here we identify a heart–brain endocrine axis in which pathological cardiac stress induces systemic elevation of the mitokine FGF21, which in turn suppresses the hypothalamic-pituitary-gonadal axis and inhibits fertility. In female mice with dilated cardiomyopathy caused by mitochondrial fission deficiency (Mff KO), we observe delayed puberty, anovulation, and hypogonadotropic hypogonadism due to blunted LH secretion and selective suppression of hypothalamic kisspeptin neurons. Exogenous kisspeptin administration restores ovulation despite persistent cardiac dysfunction. Integrated transcriptomics and metabolomics analyses reveal that the signal originates from a cardiac mitochondrial integrated stress response that drives de novo FGF21 expression in the heart. Cardiac-specific Mff re-expression abolishes the signal at its source, while genetic deletion of Fgf21 fully restores puberty and fertility even in the presence of ongoing cardiomyopathy. These findings demonstrate that cardiac-derived FGF21 acts as a key endocrine suppressor of the reproductive axis during heart failure, revealing an inter-organ communication pathway that links cardiac mitochondrial stress to reproductive control.

The postmenopausal ovary is commonly viewed as a largely quiescent organ, yet its cellular biology remains incompletely characterized. We generated a single-nucleus atlas of the aging postmenopausal human ovary comprising 439,011 nuclei across 64 ovarian samples from 28 donors. We resolved 37 cell states, revealing extensive stromal, vascular, and immune heterogeneity. We developed an interactive data explorer to facilitate interrogation of cell annotations and gene expression across the atlas. Aging was associated with expansion of stress-associated stromal states, vascular and immune depletion, and a shift toward steroidogenic and androgen-responsive programs. Several major age-associated compositional shifts were supported in an external GTEx ovary bulk RNA-seq cohort, validating relevance. Parity (1–3 versus 0 live births) was associated with transcriptional and compositional patterns broadly opposing age-associated remodeling. Our findings establish the postmenopausal ovary as an actively remodeled aging tissue and link obstetric history to molecular and cellular signatures detectable later in life.

Cellular senescence is implicated as a driver of ovarian aging, but senescent cells in the human postmenopausal ovary remain poorly defined. Using spatially resolved p16INK4a protein expression, a canonical senescence marker, we identified and mapped senescent cells in postmenopausal ovaries. We integrated p16 immunohistochemistry, multiplexed immunofluorescence, spatial transcriptomics, and AI-guided digital pathology to map senescent microenvironments. p16-positive cells formed discrete stromal, vascular, and cyst-associated clusters that increased with age and were enriched for macrophages and myofibroblast-like cells. Whole-transcriptome profiling of 92 spatial regions uncovered a 32-gene p16-associated signature, BuckSenOvary, that distinguished p16-positive regions across cortex and medulla. BuckSenOvary is characterized by suppression of cell-cycle regulators and activation of inflammatory and extracellular-matrix remodelling genes. AI-based collagen matrix analysis confirmed that p16-positive regions exhibit more architecturally complex collagen, demonstrating that focal senescent microenvironments are fibro-inflammatory. These findings position senescent ovarian niches as therapeutic targets to preserve ovarian function.

Age-related cognitive decline represents a major and unresolved challenge of human aging. Here, we identify the NAD⁺-consuming enzyme CD38 as a central regulator of cognitive aging acting through a choroid plexus–cerebrospinal fluid (CSF)–hippocampus axis. CD38 expression increases with age and localizes primarily to pericytes in the choroid plexus, where it depletes NAD⁺, impairs mitochondrial function, and promotes cellular senescence. Genetic ablation or pharmacological inhibition of CD38 restores NAD⁺ levels, suppresses senescence markers, and improves choroid plexus function, resulting in a rejuvenated CSF proteomic and metabolomic profile characterized by reduced inflammatory signaling and enhanced neurotrophic support. These changes propagate to the hippocampus, reversing age-related transcriptional signatures and enhancing synaptic plasticity. A novel, brain-penetrant CD38 inhibitor, NTX-748, reproduced the benefits of CD38 deficiency—elevating systemic and brain NAD⁺ levels, improving long-term potentiation, and enhancing multiple domains of cognition in aged mice. Collectively, these findings identify the choroid plexus as a metabolic gatekeeper of brain aging and establish CD38 inhibition as a promising therapeutic strategy to promote cognitive resilience and healthy brain aging.

Cellular senescence is implicated as a driver of ovarian aging, but senescent cells in the human postmenopausal ovary remain poorly defined. Using spatially resolved p16INK4a protein expression, a canonical senescence marker, we identified and mapped senescent cells in postmenopausal ovaries. We integrated p16 immunohistochemistry, multiplexed immunofluorescence, spatial transcriptomics, and AI-guided digital pathology to map senescent microenvironments. p16-positive cells formed discrete stromal, vascular, and cyst-associated clusters that increased with age and were enriched for macrophages and myofibroblast-like cells. Whole-transcriptome profiling of 92 spatial regions uncovered a 32-gene p16-associated signature, BuckSenOvary, that distinguished p16-positive regions across cortex and medulla. BuckSenOvary is characterized by suppression of cell-cycle regulators and activation of inflammatory and extracellular-matrix remodelling genes. AI-based collagen matrix analysis confirmed that p16-positive regions exhibit more architecturally complex collagen, demonstrating that focal senescent microenvironments are fibro-inflammatory. These findings position senescent ovarian niches as therapeutic targets to preserve ovarian function.

We demonstrate that cellular senescence contributes to doxorubicin-related vascular endothelial dysfunction and establishes efficacy for the use of senolytic therapy to improve vascular function following doxorubicin administration. Mechanistically, we found that cellular senescence reduced NO bioavailability and promoted excessive production of vascular mitochondrial superoxide-related oxidative stress, both of which were prevented with senolytic therapy. We translated these findings to humans and showed that ex vivo exposure to doxorubicin impaired arteriole endothelial function, which was prevented with senolytic exposure.