Role of cellular senescence in lifestyle-related disease

An Ex Vivo Aorta Culture Model to Study Vascular Cellular Senescence

Animal studies on vascular aging pose a few limitations. One of the most important reasons for this is the absence of a fast and efficient model of vascular tissue aging. In this study, ex vivo aortic culture and Matrigel subcutaneous implantation are combined to develop a new model for studying vascular cellular senescence. Eight-week-old C57BL/6J mice are used to obtain aortas. Bleomycin is used to induce aortas senescence in vitro. Then, aortas are transplanted to the acceptor mice with Matrigel. Senescence is evaluated using western blotting, quantitative polymerase chain reaction, and senescence-associated beta-galactosidase activity. Inflammatory cytokines are detected using Luminex Liquid Suspension Chip. RNA levels are analyzed by transcriptome sequencing. The results revealed that vessels in the bleomycin group exhibited significant senescence than those in the control group that can be enhanced by stripping vessel adventitia. The levels of cytokines such as interleukin (IL-2, IL-1β, and IL-6 increased significantly in the ex vivo model. Furthermore, transcriptome sequencing revealed 56 significantly differentially expressed genes (DEGs) in ex vivo model vessels compared with those in naturally aging aortas. In conclusion, this study introduces a cost-effective and time-saving vessel senescence model for vascular cellular senescence.

Modulation of Smooth Muscle Cell Phenotype for Translation of Tissue-Engineered Vascular Grafts

Translation of small-diameter tissue-engineered vascular grafts (TEVGs) for the treatment of coronary artery disease (CAD) remains an unfulfilled promise. This is largely due to the limited integration of TEVGs into the native vascular wall-a process hampered by the insufficient smooth muscle cell (SMC) infiltration and extracellular matrix deposition, and low vasoactivity. These processes can be promoted through the judicious modulation of the SMC toward a synthetic phenotype to promote remodeling and vascular integration; however, the expression of synthetic markers is often accompanied by a decrease in the expression of contractile proteins. Therefore, techniques that can precisely modulate the SMC phenotypical behavior could have the potential to advance the translation of TEVGs. In this review, we describe the phenotypic diversity of SMCs and the different environmental cues that allow the modulation of SMC gene expression. Furthermore, we describe the emerging biomaterial approaches to modulate the SMC phenotype in TEVG design and discuss the limitations of current techniques. In addition, we found that current studies in tissue engineering limit the analysis of the SMC phenotype to a few markers, which are often the characteristic of early differentiation only. This limited scope has reduced the potential of tissue engineering to modulate the SMC toward specific behaviors and applications. Therefore, we recommend using the techniques presented in this review, in addition to modern single-cell proteomics analysis techniques to comprehensively characterize the phenotypic modulation of SMCs. Expanding the holistic potential of SMC modulation presents a great opportunity to advance the translation of living conduits for CAD therapeutics.

Lin28b delays vasculature aging by reducing platelet-derived growth factor-beta resistance in senescent vascular smooth muscle cells

BACKGROUND AND AIMS

Platelet-derived growth factor-β (PDGFB) is an important mediator of vascular smooth muscle cell (VSMC) proliferation, and PDGFB resistance is observed in senescent VSMCs. Lin28b is a stemness regulator in the embryo; however, its role in vasculature aging and VSMC senescence is unknown. We aimed to investigate whether Lin28b could restore the VSMC response to PDGFB and delay vasculature aging.

METHODS

ApoE^-/- mice were fed a high-fat diet for different weeks to establish an aging model. PDGFB resistance was observed using EdU staining in vessel culture in vitro. Quantitative polymerase chain reaction and in situ hybridization were used to detect let-7 expression. Senescence was identified by Western blotting, senescence-associated beta-galactosidase activity or Sudan Black B staining, and VSMC function was determined using CCK-8, migration, and enzyme-linked immunosorbent assays.

RESULTS

Vessels from aged mice showed poor responses to PDGFB stimulation compared with those from young mice; similar results were found in senescent VSMCs. The expression levels of Lin28b and PDGF receptor-β were downregulated in aging vasculature and senescent VSMCs, whereas let-7 family levels increased with aging and VSMC passage growth. Transfection of VSMCs with let-7c induced PDGFB resistance and accelerated VSMC senescence, whereas blocking let-7c restored PDGFB reactions in VSMCs. Overexpression of Lin28b protein by lentivirus resulted in the restoration of PDGFB reactions and delayed VSMC senescence, which was blocked by a let-7c mimic.

CONCLUSIONS

This study reveals the role of Lin28b in delaying vasculature aging by decreasing senescent VSMC PDGFB resistance mediated by let-7.

Global research trends in atherosclerosis: A bibliometric and visualized study

Background

Increasing evidence has spurred a considerable evolution of concepts related to atherosclerosis, prompting the need to provide a comprehensive view of the growing literature. By retrieving publications in the Web of Science Core Collection (WoSCC) of Clarivate Analytics, we conducted a bibliometric analysis of the scientific literature on atherosclerosis to describe the research landscape.

Methods

A search was conducted of the WoSCC for articles and reviews serving exclusively as a source of information on atherosclerosis published between 2012 and 2022. Microsoft Excel 2019 was used to chart the annual productivity of research relevant to atherosclerosis. Through CiteSpace and VOSviewer, the most prolific countries or regions, authors, journals, and resource-, intellectual-, and knowledge-sharing in atherosclerosis research, as well as co-citation analysis of references and keywords, were analyzed.

Results

A total of 20,014 publications were retrieved. In terms of publications, the United States remains the most productive country (6,390, 31,93%). The most publications have been contributed by Johns Hopkins Univ (730, 3.65%). ALVARO ALONSO produced the most published works (171, 0.85%). With a betweenness centrality of 0.17, ERIN D MICHOS was the most influential author. The most prolific journal was identified as Atherosclerosis (893, 4.46%). Circulation received the most co-citations (14,939, 2.79%). Keywords with the ongoing strong citation bursts were “nucleotide-binding oligomerization (NOD), Leucine-rich repeat (LRR)-containing protein (NLRP3) inflammasome,” “short-chain fatty acids (SCFAs),” “exosome,” and “homeostasis,” etc.

Conclusion

The research on atherosclerosis is driven mostly by North America and Europe. Intensive research has focused on the link between inflammation and atherosclerosis, as well as its complications. Specifically, the NLRP3 inflammasome, interleukin-1β, gut microbiota and SCFAs, exosome, long non-coding RNAs, autophagy, and cellular senescence were described to be hot issues in the field.

Senescence in Vascular Smooth Muscle Cells and Atherosclerosis

Vascular smooth muscle cells (VSMCs) are the primary cell type involved in the atherosclerosis process; senescent VSMCs are observed in both aged vessels and atherosclerotic plaques. Factors associated with the atherosclerotic process, including oxidative stress, inflammation, and calcium-regulating factors, are closely linked to senescence in VSMCs. A number of experimental studies using traditional cellular aging markers have suggested that anti-aging biochemical agents could be used to treat atherosclerosis. However, doubt has recently been cast on such potential due to the increasingly apparent complexity of VSMCs status and an incomplete understanding of the role that these cells play in the atherosclerosis process, as well as a lack of specific or spectrum-limited cellular aging markers. The utility of anti-aging drugs in atherosclerosis treatment should be reevaluated. Promotion of a healthy lifestyle, exploring in depth the characteristics of each cell type associated with atherosclerosis, including VSMCs, and development of targeted drug delivery systems will ensure efficacy whilst evaluation of the safety and tolerability of drug use should be key aims of future anti-atherosclerosis research. This review summarizes the characteristics of VSMC senescence during the atherosclerosis process, the factors regulating this process, as well as an overview of progress toward the development and application of anti-aging drugs.

circ-Sirt1 Decelerates Senescence by Inhibiting p53 Activation in Vascular Smooth Muscle Cells, Ameliorating Neointima Formation

Vascular smooth muscle cell (VSMC) senescence is a major driver of neointimal formation. We have demonstrated that circ-Sirt1 derived from the SIRT1 gene suppressed VSMC inflammation and neointimal formation. However, the effect of circ-Sirt1 inhibiting inflammation on VSMC senescence during neointimal hyperplasia remains to be elucidated. Here, we showed that circ-Sirt1 was highly expressed in young and healthy arteries, which was decreased in aged arteries and neointima of humans and mice. Overexpression of circ-Sirt1 delayed Ang II-induced VSMC senescence in vitro and ameliorated neointimal hyperplasia in vivo. Mechanically, circ-Sirt1 inhibited p53 activity at the levels of transcription and post-translation modulation. In detail, circ-Sirt1, on the one hand, interacted with and held p53 to block its nuclear translocation, and on the other hand, promoted SIRT1-mediated p53 deacetylation and inactivation. In conclusion, our data suggest that circ-Sirt1 is a novel p53 repressor in response senescence-inducing stimuli, and targeting circ-Sirt1 may be a promising approach to ameliorating aging-related vascular disease.

T Cell Immunosenescence in Aging, Obesity, and Cardiovascular Disease

Although advances in preventive medicine have greatly improved prognosis, cardiovascular disease (CVD) remains the leading cause of death worldwide. This clearly indicates that there remain residual cardiovascular risks that have not been targeted by conventional therapies. The results of multiple animal studies and clinical trials clearly indicate that inflammation is the most important residual risk and a potential target for CVD prevention. The immune cell network is intricately regulated to maintain homeostasis. Ageing associated changes to the immune system occurs in both innate and adaptive immune cells, however T cells are most susceptible to this process. T-cell changes due to thymic degeneration and homeostatic proliferation, metabolic abnormalities, telomere length shortening, and epigenetic changes associated with aging and obesity may not only reduce normal immune function, but also induce inflammatory tendencies, a process referred to as immunosenescence. Since the disruption of biological homeostasis by T cell immunosenescence is closely related to the development and progression of CVD via inflammation, senescent T cells are attracting attention as a new therapeutic target. In this review, we discuss the relationship between CVD and T cell immunosenescence associated with aging and obesity.

Role of DNA damage in cardiovascular disease

Patients with some progeroid syndromes, such as Werner syndrome, exhibit atherosclerotic cardiovascular disease (CVD) at a young age as a manifestation of premature aging. Recent studies have revealed that most progeroid syndromes are caused by genetic defects in specific molecules involved in the DNA damage response, a cornerstone of genome stability. Ionizing radiation is one of the most potent genotoxic stimuli and causes various kinds of DNA damage. Further, there is increasing evidence that therapeutic radiation treatments can cause cardiovascular complications. Here, we describe the DNA damage and subsequent response, review recent advances in the understanding of the molecular basis of progeroid syndromes (especially those syndromes that involve CVD), review the pathological and epidemiological analysis of radiation-induced CVD, and discuss the possible role of DNA damage and the DNA damage response in the pathogenesis of atherosclerotic CVD.

Effect of Colla corii asini (E'jiao) on D-galactose induced aging mice

Colla corii asini (E'jiao), donkey-hide gelatin prepared by stewing and concentrating from Equus asinus L. donkey hide, is a traditional Chinese medicine preparation widely used in clinical hematic antanemic therapy in China. The aim of the present study was to investigate potential anti-aging effect of Colla corii asini and explore related mechanisms in D-galactose (gal) induced aging model mice. The mice were artificially induced aging by subcutaneously injection with D-gal at the dose of 100 mg/kg·d for 8 weeks. Colla corii asini was simultaneously treated to them once daily by intragastric gavage. Appetite, mental condition, body weight, and organ index were observed. Activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px), as well as levels of malondialdehyde (MDA) in serum, brain, and liver were determined by according assay kits. Western blotting analysis was used to detect p16 and p21 expression. Results indicated that Colla corii asini could improve appetite, mental condition, body weight, and organ condition of model mice, improve SOD, CAT, and GSH-Px activities, reduce MDA levels, and modulate age-related genes expression in D-gal induced mice. Therefore, Colla corii asini may have effect to suppress the aging process through enhancing antioxidant activity, scavenging free radicals, and modulating aging-related gene expression.

Rejuvenation of senescent cells-the road to postponing human aging and age-related disease?

Cellular senescence is the state of permanent inhibition of cell proliferation. Replicative senescence occurs due to the end replication problem and shortening telomeres with each cell division leading to DNA damage response (DDR). The number of short telomeres increases with age and age-related pathologies. Stress induced senescence, although not accompanied by attrition of telomeres, is also attributed to the DDR induced by irreparable DNA lesions in telomeric DNA. Senescent cells characterized by the presence of γH2AX, the common marker of double DNA strand breaks, and other senescence markers including activity of SA-β-gal, accumulate in tissues of aged animals and humans as well as at sites of pathology. It is believed that cellular senescence evolved as a cancer barrier since non-proliferating senescent cells cannot be transformed to neoplastic cells. On the other hand senescent cells favor cancer development, just like other age-related pathologies, by creating a low grade inflammatory state due to senescence associated secretory phenotype (SASP). Reversal/inhibition of cellular senescence could prolong healthy life span, thus many attempts have been undertaken to influence cellular senescence. The two main approaches are genetic and pharmacological/nutritional modifications of cell fate. The first one concerns cell reprogramming by induced pluripotent stem cells (iPSCs), which in vitro is effective even in cells undergoing senescence, or derived from very old or progeroid patients. The second approach concerns modification of senescence signaling pathways just like TOR-induced by pharmacological or with natural agents. However, knowing that aging is unavoidable we cannot expect its elimination, but prolonging healthy life span is a goal worth serious consideration.

Dementia and Alzheimer's disease: a new direction.The 2010 Jay L. Foster Memorial Lecture

BACKGROUND

The modern era of Alzheimer's disease (AD) research began in the early 1980s with the establishment of AD research centers and expanded research programs at the National Institute on Aging.

METHODS

Over the past 30 years, there has been success in defining criteria for AD and dementia, association of important genetic disorders related to premature dementia in families, the association of apolipoprotein-E(4), and measurement of incidence and prevalence and selected risk factors. However, prevention and treatment have been elusive.

RESULTS

The development of new technologies, especially magnetic resonance imaging, positron emission tomography to measure amyloid in vivo in the brain and glucose metabolism, cerebrospinal fluid examination, better genetic markers, large-scale longitudinal epidemiology studies, and preventive clinical trials has rapidly begun a new era of research that offers opportunities to better understand etiology, that is, determinants of amyloid biology in the brain, neurofibrillary tangles, synaptic loss, and dementia.

CONCLUSIONS

There are three major hypotheses related to dementia: amyloid deposition and secondary synaptic loss as a unique disease, vascular injury, and "aging." New research must be hypothesis-driven and lead to testable approaches for treatment and prevention.

Potential involvement of LOX-1 in functional consequences of endothelial senescence

Numerous studies have described the process of senescence associated with accumulation of oxidative damage, mutations and decline in proliferative potential. Although the changes observed in senescent cells are likely to result in significant phenotypic alterations, the studies on consequences of endothelial senescence, especially in relation to aging-associated diseases, are scarce. We have analyzed effects of senescence on the functions of endothelial cells relevant to the development of atherosclerosis including angiogenesis, adhesion, apoptosis and inflammation. In the course of progressing through the passages, human umbilical vein endothelial cells (HUVECs) displayed significant increase in size (+36% passage 12 vs. passage 4 , p<0.001) and reduction in both basal and VEGF-stimulated tube formation. The analysis of a scavenger receptor LOX-1, a key molecule implicated in atherogenesis, revealed a significant decline of its message (mRNA) and protein content in senescent endothelial cells (−33%) and in aortas of 50 wk (vs. 5 wk) old mice (all p<0.01). These effects were accompanied by a marked reduction of the basal expression of VCAM-1 and ICAM-1. Compared to early cultures, late passage HUVECs also exhibited nuclear translocation of NF-κB (p65) and reciprocal shifts in BAX and BCL2 protein content resulting in almost 2-fold increase in BAX/BCL2 ratio and 3-fold increase in apoptotic response to TNFα exposure (p<0.04). These changes in senescent endothelial cells are suggestive of aberrant responses to physiological stimuli resulting in a less permissive environment for tissue remodeling and progression of diseases requiring angiogenesis and cell adhesion in elderly, possibly, mediated by LOX-1.

Developments in Electrospray Ionization Mass Spectrometry of Non-Covalent DNA–Ligand Complexes

Many anti-cancer drugs function by binding non-covalently to double-stranded (ds) DNA. Electrospray ionization mass spectrometry (ESI-MS) has emerged over the past decade as a sensitive technique for the determination of stoichiometries and relative binding affinities of DNA–ligand interactions. The chromosome contains nucleotide sequences, for example, guanosine-rich regions, that predispose them to the formation of higher order structures such as quadruplex DNA (qDNA). Sequences that form qDNA are found in the telomeres. The proposal that ligands that stabilize qDNA might interfere with the activity of telomerase in cancer cells has stimulated the search for ligands that are selective for qDNA over dsDNA. The insights gained from the development of ESI-MS methods for analysis of non-covalent dsDNA–ligand complexes are now being applied in the search for qDNA-selective ligands. ESI-MS is a useful first-pass screening technique for qDNA-binding ligands. This short review describes some experimental considerations for ESI-MS analysis of DNA–ligand complexes, briefly addresses the question of whether non-covalent DNA–ligand complexes are faithfully transferred from solution to the gas phase, discusses ion mobility mass spectrometry as a technique for probing this issue, and highlights some recent ESI-MS studies of qDNA-selective ligands.