Chronological aging is the leading risk factor for human diseases, while aging at the cellular level, namely cellular senescence, is the fundamental driving force of organismal aging. The impact of cellular senescence on various life processes, including normal physiology, organismal aging and the progress of various age-related pathologies, has been largely ignored for a long time. However, with recent advancement in relevant fields, cellular senescence has become the core of aging biology and geriatric medicine. Although senescent cells play important roles in physiological processes including tissue repair, wound healing, and embryonic development, they can also contribute to tissue dysfunction, organ degeneration and various pathological conditions during adulthood. Senescent cells exert paracrine effects on neighboring cells in tissue microenvironments by developing a senescence-associated secretory phenotype, thus maintaining long-term and active intercellular communications that ultimately results in multiple pathophysiological effects. This is regarded as one of the most important discoveries in life science of this century. Notably, selective elimination of senescent cells through inducing their apoptosis or specifically inhibiting the senescence-associated secretory phenotype has shown remarkable potential in preclinical and clinical interventions of aging and age-related diseases. This reinforces the belief that senescent cells are the key drug target to alleviate various aging syndromes. However, senescent cells exhibit heterogeneity in terms of form, function and tissue distribution, and even differ among species, which presents a challenge for the translation of significant research achievements to clinical practice in future. This article reviews and discusses the characteristics of senescent cells, current targeting strategies and future trends, providing useful and valuable references for the rapidly blooming aging biology and geriatric medicine.
Humans ; Adult ; Aged ; Cellular Senescence/genetics* ; Aging ; Apoptosis ; Cell Communication ; Wound Healing/physiology*

Recent studies have shown that the occurrence and development of common liver diseases, including non-alcoholic fatty liver disease, cirrhosis, and liver cancer, are related to liver aging(LA). Therefore, to explore the effect and mechanism of Dahuang Zhechong Pills(DHZCP), a traditional classic prescription in improving LA with multiple targets, the present study randomly divided 24 rats into a normal group, a model group, a DHZCP group, and a vitamin E(VE) group, with six rats in each group. The LA model was induced by continuous intraperitoneal injection of D-galactose(D-gal) in rats. For the LA model rats, the general situation was evaluated by aging phenotype and body weight(BW). LA was assessed by the pathological characteristics of hepatocyte senescence, hepatic function indexes, the staining characteristics of phosphorylated histone family 2A variant(γ-H2AX), and the expression levels of cell cycle arrest proteins(P21, P53, P16) and senescence-associated secretory phenotype(SASP) in the liver. The activation of the reactive oxygen species(ROS)-mediated phosphatidylinositol-3 kinase(PI3K)/protein kinase B(Akt)/forkhead box protein O4(FoxO4) signaling pathway was estimated by hepatic ROS expression feature and the protein expression levels of the key signaling molecules in the PI3K/Akt/FoxO4 signaling pathway. The results showed that after the treatment with DHZCP or VE for 12 weeks, for the DHZCP and VE groups, the characterized aging phenotype, BW, pathological characteristics of hepatocyte senescence, hepatic function indexes, relative expression of ROS in the liver, protein expression levels of key signaling molecules including p-PI3K, p-Akt, and FoxO4 in the liver, staining characteristics of γ-H2AX, and the protein expression levels of P16, P21, P53, interleukin-6(IL-6), and tumor necrosis factor-α(TNF-α) in the liver were improved, and the effects of DHZCP and VE were similar. Based on the D-gal-induced LA model in rats, this study demonstrates that DHZCP can ameliorate LA with multiple targets in vivo, and its effects and mechanism are related to regulating the activation of the ROS-mediated PI3K/Akt/FoxO4 signaling pathway in the liver. These findings are expected to provide new pharmacological evidence for the treatment of DHZCP in aging-related liver diseases.
Animals ; Rats ; Proto-Oncogene Proteins c-akt/genetics* ; Phosphatidylinositol 3-Kinases/genetics* ; Reactive Oxygen Species ; Tumor Suppressor Protein p53/genetics* ; Signal Transduction ; Liver ; Aging ; Cell Cycle Proteins ; Interleukin-6

Aging of craniofacial skeleton significantly impairs the repair and regeneration of trauma-induced bony defects, and complicates dental treatment outcomes. Age-related alveolar bone loss could be attributed to decreased progenitor pool through senescence, imbalance in bone metabolism and bone-fat ratio. Mesenchymal stem cells isolated from oral bones (OMSCs) have distinct lineage propensities and characteristics compared to MSCs from long bones, and are more suited for craniofacial regeneration. However, the effect of epigenetic modifications regulating OMSC differentiation and senescence in aging has not yet been investigated. In this study, we found that the histone demethylase KDM4B plays an essential role in regulating the osteogenesis of OMSCs and oral bone aging. Loss of KDM4B in OMSCs leads to inhibition of osteogenesis. Moreover, KDM4B loss promoted adipogenesis and OMSC senescence which further impairs bone-fat balance in the mandible. Together, our data suggest that KDM4B may underpin the molecular mechanisms of OMSC fate determination and alveolar bone homeostasis in skeletal aging, and present as a promising therapeutic target for addressing craniofacial skeletal defects associated with age-related deteriorations.
Aging ; Cell Differentiation ; Facial Bones/physiology* ; Humans ; Jumonji Domain-Containing Histone Demethylases/genetics* ; Mesenchymal Stem Cells/cytology* ; Osteogenesis ; Osteoporosis

Aging/metabolism* ; Animals ; Gene Expression Regulation ; Macaca fascicularis ; Retina/metabolism* ; Single-Cell Analysis

Aging ; Betacoronavirus ; Coronavirus Infections ; epidemiology ; Humans ; Immune System ; Pandemics ; Pneumonia, Viral ; Single-Cell Analysis

Aging is one of the risk factors for the development of cardiovascular diseases. During the progression of cellular senescence, cells enter a state of irreversible growth arrest and display resistance to apoptosis. As a flavonoid, quercetin induces apoptosis in various cells. Accordingly, we investigated the relationship between quercetin-induced apoptosis and the inhibition of cellular senescence, and determined the mechanism of oxidative stress-induced vascular smooth muscle cell (VSMC) senescence. In cultured VSMCs, hydrogen peroxide (H₂O₂) dose-dependently induced senescence, which was associated with increased numbers of senescence-associated β-galactosidase-positive cells, decreased expression of SMP30, and activation of p53-p21 and p16 pathways. Along with senescence, expression of the anti-apoptotic protein Bcl-2 was observed to increase and the levels of proteins related to the apoptosis pathway were observed to decrease. Quercetin induced apoptosis through the activation of AMP-activated protein kinase. This action led to the alleviation of oxidative stress-induced VSMC senescence. Furthermore, the inhibition of AMPK activation with compound C and siRNA inhibited apoptosis and aggravated VSMC senescence by reversing p53-p21 and p16 pathways. These results suggest that senescent VSMCs are resistant to apoptosis and quercetin-induced apoptosis attenuated the oxidative stress-induced senescence through activation of AMPK. Therefore, induction of apoptosis by polyphenols such as quercetin may be worthy of attention for its anti-aging effects.
Aging ; AMP-Activated Protein Kinases ; Apoptosis ; Cardiovascular Diseases ; Cell Aging ; Hydrogen Peroxide ; Muscle, Smooth, Vascular ; Polyphenols ; Quercetin ; Risk Factors ; RNA, Small Interfering

Age-associated changes in immune cells have been linked to an increased risk for infection. However, a global and detailed characterization of the changes that human circulating immune cells undergo with age is lacking. Here, we combined scRNA-seq, mass cytometry and scATAC-seq to compare immune cell types in peripheral blood collected from young and old subjects and patients with COVID-19. We found that the immune cell landscape was reprogrammed with age and was characterized by T cell polarization from naive and memory cells to effector, cytotoxic, exhausted and regulatory cells, along with increased late natural killer cells, age-associated B cells, inflammatory monocytes and age-associated dendritic cells. In addition, the expression of genes, which were implicated in coronavirus susceptibility, was upregulated in a cell subtype-specific manner with age. Notably, COVID-19 promoted age-induced immune cell polarization and gene expression related to inflammation and cellular senescence. Therefore, these findings suggest that a dysregulated immune system and increased gene expression associated with SARS-CoV-2 susceptibility may at least partially account for COVID-19 vulnerability in the elderly.
Adult ; Aged ; Aged, 80 and over ; Aging ; genetics ; immunology ; Betacoronavirus ; CD4-Positive T-Lymphocytes ; metabolism ; Cell Lineage ; Chromatin Assembly and Disassembly ; Coronavirus Infections ; immunology ; Cytokine Release Syndrome ; etiology ; immunology ; Cytokines ; biosynthesis ; genetics ; Disease Susceptibility ; Flow Cytometry ; methods ; Gene Expression Profiling ; Gene Expression Regulation, Developmental ; Gene Rearrangement ; Humans ; Immune System ; cytology ; growth & development ; immunology ; Immunocompetence ; genetics ; Inflammation ; genetics ; immunology ; Mass Spectrometry ; methods ; Middle Aged ; Pandemics ; Pneumonia, Viral ; immunology ; Sequence Analysis, RNA ; Single-Cell Analysis ; Transcriptome ; Young Adult

BACKGROUND: Enhancement and maintenance of the stemness of mesenchymal stem cells (MSCs) is one of the most important factors contributing to the successful in vivo therapeutic application of these cells. In this regard, three-dimensional (3D) spheroid formation has been developed as reliable method for increasing the pluripotency of MSCs. Moreover, using a new protocol, we have previously shown that dental tissues of extracted wisdom teeth can be effectively cryopreserved for subsequent use as a source of autologous stem cells. The main purpose of this study is to analyze the stemness and in vitro osteogenic differentiation potential of 3D spheroid dental MSCs compared with conventional monolayer cultured MSCs. METHODS: In this study, MSC-characterized stem cells were isolated and cultured from long-term cryopreserved dental follicles (hDFSCs), and then 2D hDFSCs were cultured under 3D spheroid-forming conditions using a newly designed microchip dish. The spheroids (3D hDFSCs) thus produced were investigated and characterized with respect to stemness, MSC marker expression, apoptosis, cell cycle analysis, extracellular matrix (ECM) production, and osteogenic and adipogenic differentiation properties. RESULTS: In terms of MSC and senescence markers, spheroid cells showed no difference when compared with 2D hDFSCs; however, 3D hDFSCs were observed to have a higher proportion of cell cycle arrest and a larger number of apoptotic cells. Moreover, spheroids showed substantially increased levels of pluripotency marker (early transcription factors) and ECM protein expression. Compared with 2D hDFSCs, there was also a notable enhancement in the osteogenic induction potential of spheroids, although no differences were observed with respect to in vitro adipogenesis. CONCLUSION: To the best of our knowledge, this is the first study to demonstrate the application of a spheroid culture system for dental follicle-derived stem cells using a microchip dish. Although further studies are needed, including in vivo transplantation, the results obtained in this study indicate that spheroid hDFSCs derived from cryopreserved dental follicle tissues could be used as a valuable source of autologous stem cells for bone tissue regeneration.
Adipogenesis ; Aging ; Apoptosis ; Bone and Bones ; Cell Cycle ; Cell Cycle Checkpoints ; Dental Sac ; Extracellular Matrix ; Humans ; In Vitro Techniques ; Mesenchymal Stromal Cells ; Methods ; Molar, Third ; Osteogenesis ; Regeneration ; Stem Cells

OBJECTIVE: Poly (ADP-ribose) polymerase (PARP) is an important molecule in the early stress response of DNA damage, which is involved in DNA damage repair and cellular senescence. Olaparib, as PARP inhibitor, has an anti-tumor effect on high grade serous ovarian cancer, but its effects on cellular senescence have not been reported. This study intends to explore the role of olaparib in the regulation of senescence in ovarian cancer cells. METHODS: The effects of olaparib on the senescence of ovarian cancer cells were detected by using the senescence-associated β-galactosidase (SA-β-Gal) and senescence-associated heterochromatin aggregation (SAHF). Quantitative real-time polymerase chain reaction was used to analyze the senescence-associated secretory phenotype (SASP). Cell cycle and apoptosis were detected by flow cytometry. The effect of olaparib on tumor growth was analyzed in a nude mouse xenograft transplantation model. RESULTS: Long-term (6 days) treatment with olaparib (5 μM) significantly inhibited the growth of ovarian cancer cells, leading to arrest the cell cycle at G0/G1 phase, significant increase the number of positive SA-β-Gal stained cells and positive SAHF cells. The expression of P16 and retinoblastoma protein (p-RB) were significantly enhanced in SKOV3 cells under olaparib treated, meanwhile, the expression of P53 and p-RB were upregulated in A2780 cells. In OVCAR-3 cells, the expression of P53 was downregulated and p-RB was upregulated. Mice with SKOV3 xenograft transplantation was given olaparib (10 mg/kg/day) via abdominal cavity administration, the tumor volume was reduced (p < 0.01). CONCLUSION: Continuous low dosage administration of olaparib induced senescence under P16 or P53 dependent manner in ovarian cancer.
Abdominal Cavity ; Aging ; Animals ; Apoptosis ; Cell Aging ; Cell Cycle ; DNA Damage ; Flow Cytometry ; Heterochromatin ; Mice ; Mice, Nude ; Ovarian Neoplasms ; Phenotype ; Real-Time Polymerase Chain Reaction ; Retinoblastoma Protein ; Transplantation, Heterologous ; Tumor Burden

BACKGROUND AND OBJECTIVES: Angiotensin II (Ang II) has been suggested to accelerate vascular senescence, however the molecular mechanism(s) remain unknown. METHODS: We cultured human coronary artery smooth muscle cells (hCSMCs) and treated Ang II and/or fimasartan. Or we transfected adenoviral vectors expressing CYR61 (Ad-CYR61) or antisense CYR61 (Ad-As-CYR61). Cellular senescence was evaluated senescence-associated β-galactosidase (SA-β-gal) assay. The molecular mechanisms were investigated real-time PCR and western blots. RESULTS: SA-β-gal-positive cells significantly increased in Ang II-treated hCSMCs (5.77±1.43-fold compared with the control). The effect of Ang II was significantly attenuated by pretreatment with the Ang II type 1 receptor blocker, fimasartan (2.00±0.92-fold). The expression of both p53 and p16 senescence regulators was significantly increased by Ang II (p53: 1.39±0.17, p16: 1.19±0.10-fold vs. the control), and inhibited by fimasartan. Cysteine-rich angiogenic protein 61 (CYR61) was rapidly induced by Ang II. Compared with the control, Ad-CYR61-transfected hCSMCs showed significantly increased SA-β-gal-positive cells (3.47±0.65-fold). Upon transfecting Ad-AS-CYR61, Ang II-induced senescence (3.74±0.23-fold) was significantly decreased (1.77±0.60-fold). p53 expression by Ang II was significantly attenuated by Ad-AS-CYR61, whereas p16 expression was not regulated. Ang II activated ERK1/2 and p38 MAPK, which was significantly blocked by fimasartan. ERK and p38 inhibition both regulated Ang II-induced CYR61 expression. However, p53 expression was only regulated by ERK1/2, whereas p16 expression was only attenuated by p38 MAPK. CONCLUSIONS: Ang II induced vascular senescence by the ERK/p38 MAPK–CYR61 pathway and ARB, fimasartan, protected against Ang II-induced vascular senescence.
Aging ; Angiotensin II Type 1 Receptor Blockers ; Angiotensin II ; Angiotensins ; Blotting, Western ; Cell Aging ; Coronary Vessels ; Humans ; Muscle, Smooth, Vascular ; Myocytes, Smooth Muscle ; p38 Mitogen-Activated Protein Kinases ; Real-Time Polymerase Chain Reaction ; Receptor, Angiotensin, Type 1