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Mesenchymal stem cells (MSCs) have long been viewed as a promising therapeutic for musculoskeletal repair. However, regulatory concerns including tumorgenicity, inconsistencies in preparation techniques, donor-to-donor variability, and the accumulation of senescence during culture expansion have hindered the clinical application of MSCs. Senescence is a driving mechanism for MSC dysfunction with advancing age. Often characterized by increased reactive oxygen species, senescence-associated heterochromatin foci, inflammatory cytokine secretion, and reduced proliferative capacity, senescence directly inhibits MSCs efficacy as a therapeutic for musculoskeletal regeneration. Furthermore, autologous delivery of senescent MSCs can further induce disease and aging progression through the secretion of the senescence-associated secretory phenotype (SASP) and mitigate the regenerative potential of MSCs. To alleviate these issues, the use of senolytic agents to selectively clear senescent cell populations has become popular. However, their benefits to attenuating senescence accumulation in human MSCs during the culture expansion process have not yet been elucidated. To address this, we analyzed markers of senescence during the expansion of human primary adipose-derived stem cells (ADSCs), a population of fat-resident MSCs commonly used in regenerative medicine applications. Next, we used the senolytic agent fisetin to determine if we can reduce these markers of senescence within our culture-expanded ADSC populations. Our results indicate that ADSCs acquire common markers of cellular senescence including increased reactive oxygen species, senescence-associated β-galactosidase, and senescence-associated heterochromatin foci. Furthermore, we found that the senolytic agent fisetin works in a dose-dependent manner and selectively attenuates these markers of senescence while maintaining the differentiation potential of the expanded ADSCs. [ABSTRACT FROM AUTHOR]

Females show a disproportionate burden of Alzheimer's disease pathology and higher Alzheimer's disease dementia prevalences compared to males, yet the mechanisms driving these vulnerabilities are unknown. There is sexual dimorphism in immunological functioning, and neuroimmune processes are implicated in Alzheimer's disease genesis. Using neuropathology indicators from human brain tissue, we examined the mediational role of microglial activation on the relationship between amyloid and tau and how it differs by sex. 187 decedents (64% female; 89 mean age at death; 62% non-demented) from the Rush Memory and Aging Project completed neuropathological evaluations with brain tissue quantified for microglial activation, amyloid-β and tau. Proportion of morphologically activated microglia was determined via immunohistochemistry (HLA-DP-DQ-DR) and morphological staging (stage I, II or III). Amyloid-β and tau burden were quantified via immunohistochemistry (M00872 or AT8, respectively). Using causal counterfactual modelling, we estimated the mediational effect of microglial activation on the amyloid-β to tau relationship in the whole sample and stratified by sex (amyloid-β → microglial activation → tau). Alternative models tested the role of microglia activation as the precipitating event (microglial activation → amyloid-β → tau). Microglial activation significantly mediated 33% [95% confidence interval (CI) 10-67] of the relationship between amyloid-β and tau in the whole sample; stratified analyses suggested this effect was stronger and only statistically significant in females. 57% (95% CI 22-100) of the effect of amyloid-β on tau was mediated through microglial activation in females, compared to 19% (95% CI 0-64) in males. Regional analyses suggested that mediational effects were driven by greater cortical versus subcortical microglial activation. Relationships were independent of cerebrovascular disease indices. Alternative models suggested that in females, microglial activation was a significant exposure both preceding the amyloid-β to tau relationship (mediational effect: 50%, 95% CI 23-90) and directly related to tau burden (microglia direct effect: 50%, 95% CI 10-77). By contrast, in males, only the direct effect of microglial activation to tau reached significance (74%, 95% CI 32-100) (mediational effect: 26%, 95% CI 0-68). Our models suggest a reciprocal, bidirectional relationship between amyloid-β and microglial activation that significantly accounts for tau burden in females. By contrast, in males, direct independent (non-mediational) relationships between microglial activation or amyloid-β with tau were observed. Microglial activation may be disproportionately important for Alzheimer's disease pathogenesis in females. Determining sex-specific vulnerabilities to Alzheimer's disease development both inform fundamental pathophysiology and support precision health approaches for this heterogeneous disease. [ABSTRACT FROM AUTHOR]

Study Question: Does age affect endometrial gene expression?Summary Answer: Using unsupervised artificial intelligence methods, we report for the first time that endometrial gene expression changes from 35 years of age in women.What Is Known Already: Female fertility declines with age, largely attributed to declining oocyte quality and ovarian reserve. Combined with other evidence, a longstanding paradigm holds that age does not affect the endometrial function and age has not been controlled for properly in endometrial studies.Study Design, Size, Duration: A retrospective in silico analysis was performed of endometrial transcriptomic data from the Gene Expression Omnibus (GEO) sample repository for 27 women of different ages. Results were validated in an independent gene expression dataset of 20 endometrial samples from women aged 23-43 years.Participants/materials, Setting, Methods: A systematic search was performed in GEO from October 2016 to January 2019 to identify transcriptomic studies involving women of different ages. Included samples were from norm-ovulatory, women of reproductive age (23-49 years) with regular menstrual cycles who were free of endometriosis and used as controls in a previous endometrial study. We used raw gene expression data and metadata from these samples to investigate the effect of age on endometrial gene expression. Files were downloaded, pre-processed and explored for potential confounding variables and outliers. Artificial intelligence methods were applied to define age groups, and differential expression and functional analyses were applied to demonstrate and understand the effect of age on gene expression at the molecular level. Functional results were validated in an independent gene expression dataset of 20 endometrial samples from women aged 23-43 years.Main Results and the Role Of Chance: Analysis of the initially retrieved endometrial datasets revealed the age of participants was not available (33.33%) or traceable (43.33%) in most studies. However, one study was suitable for age analysis (GSE4888, n = 27, 23-49 years). Samples showed different transcriptomic profiles according to age, beginning at 35 years. A total of 5778 differentially expressed genes and 27 significantly altered endometrial functions (false discovery rate (FDR) < 0.05) were associated with endometrial gene expression changes related to age. Interestingly, 81.48% of affected functions were related to up-regulation of ciliary processes, with 91 genes involved in cilia motility and ciliogenesis. Other functions included dysregulation of the vascular endothelial growth factor signalling pathway and inhibition of epithelial proliferation triggered by 37 genes involved in cell cycle arrest, angiogenesis, insulin signalling and telomere protection. These findings were validated in an independent dataset using a non-targeted approach; 20 up-regulated ciliary processes (FDR < 0.02) and 6 down-regulated functions related to cell cycle arrest were identified as affected by age, among other hallmarks of ageing such as DNA repair inhibition or sugar metabolism (FDR < 0.05).Large Scale Data: Data underlying this article are available in GEO, IDs: GSE4888 (main dataset) and GSE102131 (validation dataset).Limitations, Reasons For Caution: This study is limited in size, as are most studies of endometrial transcriptomics where whole-transcriptome analysis considers nearly 22 000 variables in a relatively small population. Yet, our study includes a main sample set and subsequent validation set that enhances reproducibility of our results and provides reasonable evidence for concluding that age affects endometrial gene expression. A larger study prospectively controlling for patient characteristics is needed to accurately describe changes related to age, with a higher sample size and across a wide age range. Additional studies also are necessary to determine the endometrial ageing contribution to infertility for ultimate translation to a clinical setting.Wider Implications Of the Findings: Our findings support an influence of age on the endometrium in a genome-wide functional approach, breaking the endometrial ageing paradigm in human reproduction. To our knowledge, this work is the first to identify, using a genome-wide functional non-targeted approach, ciliary processes as the primary dysregulated function associated with maternal age. These results should guide the research community to control for age as a potential confounding variable in endometrial gene expression studies and to consider endometrial ageing in further studies as a potential cause of infertility in the clinical setting. The reported functional dysregulations could contribute to diminished embryo implantation with age and further studies will demonstrate if such dysregulation underlies some cases of implantation failure. Additionally, the discovery of these functional alterations could enable mechanistic studies, particularly around the age-related increase in uterine pathologies.Study Funding/competing Interest(s): This research was funded by the Instituto de Salud Carlos III through Miguel Servet programme (CP20/00118) granted to Patricia Diaz-Gimeno (Spanish Government) co-funded by FEDER; and by IVI Foundation (1706-FIVI-041-PD). A.D.-P. (FPU/15/01398) and A.P.-L. (FPU18/01777) are granted by the pre-doctoral programme fellowship from the Ministry of Science, Innovation and Universities (Spanish Government). The authors do not have any competing interests to declare.Trial Registration Number: N/A. [ABSTRACT FROM AUTHOR]

A critical property of many therapies is their selective binding to target populations. Exceptional specificity can arise from high-affinity binding to surface targets expressed exclusively on target cell types. In many cases, however, therapeutic targets are only expressed at subtly different levels relative to off-target cells. More complex binding strategies have been developed to overcome this limitation, including multi-specific and multivalent molecules, creating a combinatorial explosion of design possibilities. Guiding strategies for developing cell-specific binding are critical to employ these tools. Here, we employ a uniquely general multivalent binding model to dissect multi-ligand and multi-receptor interactions. This model allows us to analyze and explore a series of mechanisms to engineer cell selectivity, including mixtures of molecules, affinity adjustments, valency changes, multi-specific molecules and ligand competition. Each of these strategies can optimize selectivity in distinct cases, leading to enhanced selectivity when employed together. The proposed model, therefore, provides a comprehensive toolkit for the model-driven design of selectively binding therapies. [ABSTRACT FROM AUTHOR]

Mechanical properties such as substrate stiffness are a ubiquitous feature of a cell's environment. Many types of animal cells exhibit canonical phenotypic plasticity when grown on substrates of differing stiffness, in vitro and in vivo. Whether such plasticity is a multivariate optimum due to hundreds of millions of years of animal evolution, or instead is a compromise between conflicting selective demands, is unknown. We addressed these questions by means of experimental evolution of populations of mouse fibroblasts propagated for approximately 90 cell generations on soft or stiff substrates. The ancestral cells grow twice as fast on stiff substrate as on soft substrate and exhibit the canonical phenotypic plasticity. Soft-selected lines derived from a genetically diverse ancestral population increased growth rate on soft substrate to the ancestral level on stiff substrate and evolved the same multivariate phenotype. The pattern of plasticity in the soft-selected lines was opposite of the ancestral pattern, suggesting that reverse plasticity underlies the observed rapid evolution. Conversely, growth rate and phenotypes did not change in selected lines derived from clonal cells. Overall, our results suggest that the changes were the result of genetic evolution and not phenotypic plasticity per se. Whole-transcriptome analysis revealed consistent differentiation between ancestral and soft-selected populations, and that both emergent phenotypes and gene expression tended to revert in the soft-selected lines. However, the selected populations appear to have achieved the same phenotypic outcome by means of at least two distinct transcriptional architectures related to mechanotransduction and proliferation. [ABSTRACT FROM AUTHOR]