Cellular senescence in normal and adverse pregnancy

Cellular senescence (CS) is defined as a state of terminal proliferation arrest accompanied by morphological alterations, pro-inflammatory phenotype, and metabolic changes. In recent years, the implications of senescence in numerous physiological and pathological conditions such as development, tissue repair, aging, or cancer have been evident. Some inductors of senescence are tissue repair pathways, telomere shortening, DNA damage, degenerative disorders, and wound healing. Lately, it has been demonstrated that CS plays a decisive role in the development and progression of healthy pregnancy and labor. Premature maternal-fetal tissues senescence (placenta, choriamniotic membranes, and endothelium) is implicated in many adverse pregnancy outcomes, including fetal growth restriction, preeclampsia, preterm birth, and intrauterine fetal death. Here we discuss cellular senescence and its association with normal pregnancy development and adverse pregnancy outcomes. Current evidence allows us to establish the relevance of CS in processes associated with the appropriate development of placentation, the progression of pregnancy, and the onset of labor; likewise, it allows us to understand the undeniable participation of CS deregulation in pathological processes associated with pregnancy.

Single-Run Catalysis and Kinetic Control of Human Telomerase Holoenzyme

Genome stability in eukaryotic cells relies on proper maintenance of telomeres at the termini of linear chromosomes. Human telomerase holoenzyme is required for maintaining telomere stability in a majority of proliferative human cells, making it essential for control of cell division and aging, stem cell maintenance, and development and survival of tumor or cancer. A dividing human cell usually contains a limited number of active telomerase holoenzymes. Recently, we discovered that a human telomerase catalytic site undergoes catalysis-dependent shut-off and an inactive site can be reactivated by cellular fractions containing human intracellular telomerase-activating factors (hiTAFs). Such ON-OFF control of human telomerase activity suggests a dynamic switch between inactive and active pools of the holoenzymes. In this review, we will link the ON-OFF control to the thermodynamic and kinetic properties of human telomerase holoenzymes, and discuss its potential contributions to the maintenance of telomere length equilibrium. This treatment suggests probabilistic fluctuations in the number of active telomerase holoenzymes as well as the number of telomeres that are extended in a limited number of cell cycles, and may be an important component of a fully quantitative model for the dynamic control of telomerase activities and telomere lengths in different types of eukaryotic cells.

Features to consider for mimicring tissues in orofacial aesthetics with optimal balance technology and non-animal stabilized hyaluronic acid (Restylane®): The MIMT concept

Nonsurgical cosmetic treatments have significantly increased over the last decade. Therefore, this study aims to review the features that should be considered in orofacial esthetic procedures, thorough of a proposal of a new concept called the tissue mimicry concept (MIMT concept) and filling techniques. The MIMT concept described in this article comprises knowledge about anatomy of the face and associated structures, understanding of aging and how this process affects the facial tissues interactions (skin, subcutaneous tissues, muscles, and bones), interpretation of facial analysis, comprehension of dermal fillers characteristics and discernment of the correct filling technique for each region. Based on these variables the MIMT concept proposes the implantation of the minimum-effective quantity of acid hyaluronic fillers (HA) with different physical, chemical and rheological properties (complex viscosity and elastic modulus) in the correct layers; in order to optimize their performance resulting in a natural appearance with fewer risks of adverse events. the versatility, acceptable safety profile, biocompatibility and greater patient compliance presented in the Restylane® line (by Galderma) should be taken in consideration, since the use of a proper HA is noteworthiness. The Non-Animal Stabilized Hyaluronic Acid Tecnology (NASHA®) and the Optimal Balance Technology (OBT®), which make up this line of fillers, allow us to have very firm to very flexible gels, with different particle sizes, with an optimal concentration of HA and with viscoelastic and biocompatible characteristics according to the region of the treated face.

Melatonin induces the rejuvenation of long-term ex vivo expanded periodontal ligament stem cells by modulating the autophagic process

Background

Stem cells that have undergone long-term ex vivo expansion are most likely functionally compromised (namely cellular senescence) in terms of their stem cell properties and therapeutic potential. Due to its ability to attenuate cellular senescence, melatonin (MLT) has been proposed as an adjuvant in long-term cell expansion protocols, but the mechanism underlying MLT-induced cell rejuvenation remains largely unknown.

Methods

Human periodontal ligament stem cells (PDLSCs) were isolated and cultured ex vivo for up to 15 passages, and cells from passages 2, 7, and 15 (P2, P7, and P15) were used to investigate cellular senescence and autophagy change in response to long-term expansion and indeed the following MLT treatment. Next, we examined whether MLT could induce cell rejuvenation by restoring the autophagic processes of damaged cells and explored the underlying signaling pathways. In this context, cellular senescence was indicated by senescence-associated β-galactosidase (SA-β-gal) activity and by the expression of senescence-related proteins, including p53, p21, p16, and γ-H2AX. In parallel, cell autophagic processes were evaluated by examining autophagic vesicles (by transmission electronic microscopy), autophagic flux (by assessing mRFP-GFP-LC3-transfected cells), and autophagy-associated proteins (by Western blot assay of Atg7, Beclin-1, LC3-II, and p62).

Results

We found that long-term in vitro passaging led to cell senescence along with impaired autophagy. As expected, MLT supplementation not only restored cells to a younger state but also restored autophagy in senescent cells. Additionally, we demonstrated that autophagy inhibitors could block MLT-induced cell rejuvenation. When the underlying signaling pathways involved were investigated, we found that the MLT receptor (MT) mediated MLT-related autophagy restoration by regulating the PI3K/AKT/mTOR signaling pathway.

Conclusions

The present study suggests that MLT may attenuate long-term expansion-caused cellular senescence by restoring autophagy, most likely via the PI3K/AKT/mTOR signaling pathway in an MT-dependent manner. This is the first report identifying the involvement of MT-dependent PI3K/AKT/mTOR signaling in MLT-induced autophagy alteration, indicating a potential of autophagy-restoring agents such as MLT to be used in the development of optimized clinical-scale cell production protocols.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02322-9.

Metabolomic and quality data for early and late passages of an antibody-producing industrial CHO cell line

In this article, we provide four data sets for an industrial Chinese Hamster Ovary (CHO) cell line producing antibodies during a 14-day bioreactor run. This cell line was selected for further evaluation because of its significant titer loss as the cells were passaged over time. Four conditions that differed in cell bank ages were run for this dataset. Specifically, cells were passaged to passage 12, 21, 25, and 37 and then used in this experiment. Once the run commenced the following datasets were gathered: 1). Glycosylation data for each reactor 2). Size Exclusion Chromatography (SEC) data for the antibodies produced which allowed for the identification of high and low molecular weight species in the samples (N-Glycan and SEC data was taken on day 14 only). 3/4). Metabolites levels measured using Nuclear Magnetic Resonance (NMR) and liquid chromatography-mass spectroscopy (LC-MS) for all reactors over the time course of days 1, 4, 6, 8, 12, and 14. We also provide a graph of the glutamine levels for cells of different ages as an example of the utility of the data. These metabolomics data provide relative amounts for 36 metabolites (NMR) and 109 metabolites (LC-MS) over the 14-day time course. These data were collected in connection with a co-submitted paper [1].

Gene expression in human mesenchymal stem cell aging cultures: modulation by short peptides

Effects of the short peptides Ala-Glu-Asp (AED), Lys-Glu-Asp (KED) and Lys-Glu (KE) on the expression of IGF1, FOXO1, TERT, TNKS2, and NFκB genes were studied in human embryo bone marrow mesenchymal stem cells (line FetMSCs) variously aged in "passages" or "stationary" cultures. Both cell aging models were similar in gene expression. The main difference was in the TERT gene expression level, which showed an eightfold increase at the "stationary" aging. IGF1 gene expression levels were very similar in both cell culture aging models, being enhanced by 3.5-5.6 fold upon the addition of the peptides. The FOXO1 gene was expressed twice more actively in the "stationary" than in the "passages" aging model. KED peptide inhibited FOXO1 gene expression by 1.6-2.3 fold. KE peptide increased FOXO1 gene expression by about two-fold in the "stationary" aging model but did not affect it in the "passage" aging model. The most striking difference in the peptide effect on cell aging between "passages" and "stationary" aging models was in the KED effects on TNKS2 gene expression; this expression was inhibited by KED in the "passages" model, while stimulation was observed in the "stationary" model. AED, KED, and KE stimulated expression of the NFκB gene in both models. Thus, the peptides studied at nanomolar concentrations modulate the expression of some genes known to be involved in cell aging.

The link between endometrial stromal cell senescence and decidualization in female fertility: the art of balance

Cell senescence seems to be an ambivalent biological phenomenon in many aspects. At the cellular level it is considered as an irreversible cell-cycle arrest commonly caused by the DNA damage. Senescent cells harbor a lot of impairments in various intracellular systems. Presence of senescent cells within tissues should ultimately lead to their malfunctioning. However, the interlink between cellular senescence and tissue/organismal functioning is far from always being unidirectional. The entangled and complex relationship between senescence and tissue-specific decidual differentiation of endometrial stromal cells (ESCs) is the excellent example reflecting dualism of cellular senescence. ESCs decidualization conditions endometrium responsiveness to embryonic signals and plays a critical role in embryo biosensoring, selection and implantation. Based on the analysis of the existing literary data, here we will try (1) to puzzle out how cellular senescence simultaneously may be an integral part of normal decidualization and may be involved in the progression of repeated implantation failures and recurrent pregnancy losses; (2) to suppose the sequence of cellular events reflecting the role of ESCs' senescence during normal and impaired decidualization. Together, the deep scan of the interlink between ESCs' senescence and decidualization will allow to suggest the preferable application scheme for senolytics targeting senescent cells as a possible approach to restore impaired endometrial receptivity and thus to increase the effectiveness of in vitro fertilization cycles.

Three-dimensional self-assembling nanofiber matrix rejuvenates aged/degenerative human tendon stem/progenitor cells

The poor healing capacity of tendons is known to worsen in the elderly. During tendon aging and degeneration, endogenous human tendon stem/progenitor cells (hTSPCs) experience profound pathological changes. Here, we explored a rejuvenation strategy for hTSPCs derived from aged/degenerated Achilles tendons (A-TSPCs) by providing three-dimensional (3D) nanofiber hydrogels and comparing them to young/healthy TSPCs (Y-TSPCs). RADA peptide hydrogel has a self-assembling ability, forms a nanofibrous 3D niche and can be further functionalized by adding RGD motifs. Cell survival, apoptosis, and proliferation assays demonstrated that RADA and RADA/RGD hydrogels support A-TSPCs in a comparable manner to Y-TSPCs. Moreover, they rejuvenated A-TSPCs to a phenotype similar to that of Y-TSPCs, as evidenced by restored cell morphology and cytoskeletal architecture. Transmission electron, confocal laser scanning and atomic force microscopies demonstrated comparable ultrastructure, surface roughness and elastic modulus of A- and Y-TSPC-loaded hydrogels. Lastly, quantitative PCR revealed similar expression profiles, as well a significant upregulation of genes related to tenogenesis and multipotency. Taken together, the RADA-based hydrogels exert a rejuvenating effect by recapitulating in vitro specific features of the natural microenvironment of human TSPCs, which strongly indicates their potential to direct cell behaviour and overcome the challenge of cell aging and degeneration in tendon repair.

Loving-kindness meditation slows biological aging in novices: Evidence from a 12-week randomized controlled trial

Combinations of multiple meditation practices have been shown to reduce the attrition of telomeres, the protective caps of chromosomes (Carlson et al., 2015). Here, we probed the distinct effects on telomere length (TL) of mindfulness meditation (MM) and loving-kindness meditation (LKM). Midlife adults (N = 142) were randomized to be in a waitlist control condition or to learn either MM or LKM in a 6-week workshop. Telomere length was assessed 2 weeks before the start of the workshops and 3 weeks after their termination. After controlling for appropriate demographic covariates and baseline TL, we found TL decreased significantly in the MM group and the control group, but not in the LKM group. There was also significantly less TL attrition in the LKM group than the control group. The MM group showed changes in TL that were intermediate between the LKM and control groups yet not significantly different from either. Self-reported emotions and practice intensity (duration and frequency) did not mediate these observed group differences. This study is the first to disentangle the effects of LKM and MM on TL and suggests that LKM may buffer telomere attrition.

Accumulating Transcriptome Drift Precedes Cell Aging in Human Umbilical Cord-Derived Mesenchymal Stromal Cells Serially Cultured to Replicative Senescence

In preclinical studies, mesenchymal stromal cells (MSCs) exhibit robust potential for numerous applications. To capitalize on these benefits, cell manufacturing and delivery protocols have been scaled up to facilitate clinical trials without adequately addressing the impact of these processes on cell utility nor inevitable regulatory requirements for consistency. Growing evidence indicates that culture-aged MSCs, expanded to the limits of replicative exhaustion to generate human doses, are not equivalent to early passage cells, and their use may underpin reportedly underwhelming or inconsistent clinical outcomes. Here, we sought to define the maximum expansion boundaries for human umbilical cord-derived MSCs, cultured in chemically defined xeno- and serum-free media, that yield consistent cell batches comparable to early passage cells. Two male and two female donor populations, recovered from cryostorage at mean population doubling level (mPDL) 10, were serially cultivated until replicative exhaustion (senescence). At each passage, growth kinetics, cell morphology, and transcriptome profiles were analyzed. All MSC populations displayed comparable growth trajectories through passage 9 (P9; mPDL 45) and variably approached senescence after P10 (mPDL 49). Transcription profiles of 14,500 human genes, generated by microarray, revealed a nonlinear evolution of culture-adapted MSCs. Significant expression changes occurred only after P5 (mPDL 27) and accumulated rapidly after P9 (mPDL 45), preceding other cell aging metrics. We report that cryobanked umbilical cord-derived MSCs can be reliably expanded to clinical human doses by P4 (mPDL 23), before significant transcriptome drift, and thus represent a mesenchymal cell source suited for clinical translation of cellular therapies. Stem Cells Translational Medicine 2019;8:945&958.

[A study on alterations in mitochondrial biological characteristics during cellular senescence of human embryonic lung fibroblasts]

Objective: To study the alterations of mitochondrial biological characteristics during both cellular replicative and premature senescence induced by hydrogen peroxide in human embryonic lung fibroblasts (HEFs). Methods: The premature senescence was induced by 400 μmol/L H(2)O(2) once a day at the same time and with 2 hours each time, after four consecutive days the premature senescence models were classified into premature senescence initiation group (PSi) and premature senescence persistence group (PSp). Based on the life span of HEFs, the cell replicative senescence was divided into five groups included young-age (22 PDL), middle-age (35 PDL), replicative senescence (49 PDL), PSi and PSp. The mitochondrial distribution, relative content, adenosine triphosphate (ATP) contents, 8-hydroxydeoxyguanosine (8-OHdG) levels, the relative mitochondrial transcription factor A (TFAM) as well as mitochondrial DNA methyltransferase 1 (mtDNMT1) mRNA levels, mtDNA copy number, the relative TFAM protein level and the total enzyme activity of mitochondrial DNA methyltransferases (mtDNMTs) were detected in five senescence groups. Results: The mtDNA copy number, 8-OHdG contents, level of mtDNMT1 mRNA and mtDNMTs activity in 49 PDL group were higher than those in 22 PDL group (all P values <0.05); The level of 8-OHdG in PSi was higher than that in 22 PDL group (P<0.05); The ATP contents, mtDNA copy number, the mRNA and protein expression levels of TFAM and mtDNMTs activity of PSp were higher than those in 22 PDL group (all P values<0.05). Conclusion: During the cellular senescence of HEFs, the higher mtDNA copy number and mtDNMTs activity were common features regardless of replicative or premature senescence, with possibility that oxidative stress was involved in modifying the occurrence of premature senescence.

[The relationship between simple numerical function and gray matter volume in normal brain aging]

Objective: To explore the relationship between simple numerical function and gray matter volume (GMV) in normal brain aging using the voxel-based morphometry(VBM) approach. Methods: A total of 123 individuals from 18 to 70 years old (63 males,60 females,the average age was (43±14) years, were recruited from right-handed healthy Han Chinese volunteers at the Department of MRI at the First Affiliated Hospital of Zhengzhou University between October 2016 and June 2017. All subjects underwent magnetic resonance sagital three-dimensional imaging scanning, and statistical parameter graph (SPM) 8 software was used for voxel-based morphological analysis to compare the differences in gray matter volume between different age groups.Gray matter volume difference brain regions between different age groups were extracted as regions of interest, and correlation analysis was carried out on the score of simple numerical calculation to find the responsible atrophy brain regions related to the decline of simple digital computing ability. Results: The brain regions with different gray matter volume in different age groups mainly included bilateral frontal gyrus, bilateral anterior cingulate gyrus, bilateral middle cingulate gyrus, bilateral olfactory cortex, bilateral caudate nucleus and bilateral insula. Among them the GMV of bilateral superior frontal gyrus and anterior cingulate gyrus showed the strongest correlation with the simple numerical function. Before removing the effect of age, the correlation between the GMV of the bilateral superior frontal gyrus and medial cingulate gyrus and the corrected count of correct was significant (r=0.403,P=0.000), the correlation between GMV and the percent of correct was also significant (r=0.229,P=0.037).After removing age as a covariate, bilateral superior frontal gyrus and central cingulate gyrus were still positively correlated with the correct number after correction of simple numerical calculation function (r=0.225,P=0.014) and the correct percentage (r=0.245, P=0.007). Conclusion: There is extensive gray matter volume atrophy during the normal brain aging process. The decrease of simple numerical function in normal brain aging may be related to the decrease of frontal and anterior cingulate gray matter volume.

Age related changes in cell stiffness of tendon stem/progenitor cells and a rejuvenating effect of ROCK-inhibition

Tendon stem/progenitor cells (TSPC) are potential targets for regenerative medicine and the treatment of tendon injuries. The frequency of such injuries increases in elderly patients while the proportion of functional TSPCs in tendon tissue decreases, protracting tendon repair. Using atomic force microscopy (AFM), we show that cell stiffness and size increase in TSPCs isolated from elderly patients (A-TSPC) compared to TSPCs from younger patients (Y-TSPC). Additionally, two-photon excited fluorescence (TPEF) microscopy revealed a denser, well-structured actin cytoskeleton in A-TSPC, which correlates with the augmented cell stiffness. Treating A-TSPC with ROCK-inhibitor, reverses these age-related changes, and has rejuvenating effect on cell morphology and stiffness. We assume that cellular stiffness is a suitable marker for cell aging and ROCK a potential target for therapeutic applications of cell rejuvenation.

Leukocyte telomere length in patients with bipolar disorder: An updated meta-analysis and subgroup analysis by mood status

The purpose of the present meta-analysis was to compare leukocyte telomere length (LTL), a proposed marker for cell aging, between patients with bipolar disorder (BD) and healthy controls and explore potential moderators for the LTL difference. We searched for the major research databases up to May 2018 for studies that examined LTL in patients with BD and healthy controls. The effect sizes (ESs) of LTL differences from the included studies were pooled using a random-effects model. Furthermore, we adopted subgroup analysis to investigate whether mood status of BD patients or methods for measuring telomere length may influence such differences. We included 10 studies, with a total of 579 patients and 551 controls, in the current meta-analysis and observed significantly shorter LTL in BD patients compared to control subjects. Such differences were found in studies with patients in all mood statuses and in studies using different methods for measuring telomere length. Late-stage BD patients demonstrated more significant LTL shortening than early-stage BD patients. Our current results support the hypothesis of accelerated aging in BD patients. In the future, further properly controlled longitudinal studies are warranted to determine whether LTL changes with disease status or medication use in BD patients.

Aerobic exercise lengthens telomeres and reduces stress in family caregivers: A randomized controlled trial - Curt Richter Award Paper 2018

STUDY DESIGN

Family members caring for chronically ill relatives are typically sedentary, chronically stressed, and at high risk of disease. Observational reports suggest caregivers have accelerated cellular aging as indicated by shorter leukocyte telomere lengths. We performed a randomized controlled trial to examine the effect of aerobic exercise on changes in telomerase levels (primary outcome) and telomere lengths (secondary outcome) in inactive caregivers.

METHODS

68 female and male community dwelling dementia caregivers who reported high stress and physical inactivity were randomly assigned to a highly supervised aerobic exercise intervention vs. waitlist control group for 24 weeks. Average leukocyte telomere lengths and peripheral blood mononuclear cells' telomerase activity were measured pre- and post-intervention. All staff completing blood draws, fitness testing and bioassays were blinded to group assignment.

RESULTS

The intervention group completed approximately 40 min of aerobic exercise 3-5 times per week, verified by actigraphy. There was high (81%) adherence to 120 min/week of aerobic exercise. Groups did not significantly differ in telomerase activity changes across time, but had significant different telomere length changes across time (67.3 base pairs, 95%CI 3.1, 131.5). There were also significant reductions in body mass index and perceived stress and an increase in cardiorespiratory fitness (i.e., VO_2peak) in the exercising caregivers versus controls.

CONCLUSION

In the context of a highly controlled intervention, exercise can induce apparent telomere lengthening, though the mechanisms remain elusive. Our study underscores the importance of increasing participation in aerobic exercise to improve markers of health and attenuate cellular aging in high-risk samples.

Detection of 4977-bp deletion of mitochondrial DNA in in vitro fertilization failure women: A case-control study

BACKGROUND

The quality of oocyte is often considered as a limiting factor for fertility, especially IVF. Some mitochondrial mutations, particularly the 4977-bp deletion increase with the age. Thus, this mutation can serve as a marker for cell aging, which indicates the reduced quality of the oocytes for fertilization. It has been suggested that this can also be investigated in the blood cells of women with IVF failure.

OBJECTIVE

1-Determination of the frequency of 4977-bp deletion in women with IVF failure, 2-Investigation of the relationship between 4977-bp deletion and the age of patients.

MATERIALS AND METHODS

Polymerase chain reaction was used to detect the 4977-bp deletion in blood samples of 52 IVF failure women and 52 women who had at least one healthy child. After polymerase chain reaction with deleted and wild-type primers, the products were examined using agarose gel electrophoresis.

RESULTS

48.07% of women with IVF failure and 34.62% of healthy women had a mitochondrial 4977-bp deletion, with p=0.163 and OR: 1.749. Also, in association with the age of these patients and the frequency of 4977-bp mutation, p and OR were obtained 0.163 and 1.749, respectively and frequency of this mutation was higher in patients over 35 yr old compared to other subgroups (Patients ≥35: 57.69).

CONCLUSION

According to the findings of this study, there is no a significant relationship between the frequency of mitochondrial 4977-bp mutation and failure in IVF.

[High mechanical stretch stress promotes degeneration of the human nucleus pulposus cells through NF-κb signaling pathway]

Objective: To investigate the effect of high mechanical stretch stress(HMS)on human nucleus pulposus cells and its regulatory mechanism. Methods: The non-degenerated nucleus pulposus tissue (Pfirrmann<grade Ⅲ) removed from the patient's surgery was harvested and the human nucleus pulposus cells were isolated and cultured. In the presence or absence of pretreatment with the NF-κB specific blocker Bay11-7082, the cultured human nucleus pulposus cells were loaded cyclic mechanical stretch stress(CMS) with different parameters using the Flexercell system.The cell culture medium was collected and the secretion of inflammatory cytokines was detected by Elisa. The nucleus pulposus cells loaded with cyclic mechanical stretch stress(CMS) was collected, the changes of NF-κB/P65 signal pathway were detected, The mRNA and protein levels' expression changes were detected by RT-PCR and WB; after human nucleus pulposus cells were exposed to IL-1β, with or without Bay11-7082, the changes of P65 were detected by immunofluorescence. Results: Those mechanical stretch stress of high amplitude (9%, 19%), low frequency (0.01 Hz) and long duration (72 h) led to degeneration of human nucleus pulposus cells, while the mechanical stretch stress of low amplitude (3%), low frequency and long duration could not promote the degeneration process; the mechanical stretch stress of high amplitude(19%), low-frequency(0.01 Hz) could promote the release of inflammatory cytokines of human nucleus pulposus cells after 24 h duration; high-amplitude, low-frequency mechanical stretch stress could activate the NF-κB signaling pathway in human nucleus pulposus cells, Bay11-7082 could block the process; immunofluorescence showed that IL-1β could promote the phosphorylation of P65 in the cytoplasm of human nucleus pulposus cells and promote the entry of P65 into the cell nucleus process, Bay11-7082 could block those processes; Bay11-7082, the specific blocking agent of NF-κB signaling pathway, could block the degeneration process of human nucleus pulposus cells induced by high cyclic mechanical stretch stress(CMS) in a dose-dependent. Conclusions: High cyclic mechanical stretch stress promotes human nucleus pulposus cells degeneration through NF-κB signaling pathway.

Insight meditation and telomere biology: The effects of intensive retreat and the moderating role of personality

A growing body of evidence suggests that meditation training may have a range of salubrious effects, including improved telomere regulation. Telomeres and the enzyme telomerase interact with a variety of molecular components to regulate cell-cycle signaling cascades, and are implicated in pathways linking psychological stress to disease. We investigated the effects of intensive meditation practice on these biomarkers by measuring changes in telomere length (TL), telomerase activity (TA), and telomere-related gene (TRG) expression during a 1-month residential Insight meditation retreat. Multilevel analyses revealed an apparent TL increase in the retreat group, compared to a group of experienced meditators, similarly comprised in age and gender, who were not on retreat. Moreover, personality traits predicted changes in TL, such that retreat participants highest in neuroticism and lowest in agreeableness demonstrated the greatest increases in TL. Changes observed in TRGs further suggest retreat-related improvements in telomere maintenance, including increases in Gar1 and HnRNPA1, which encode proteins that bind telomerase RNA and telomeric DNA. Although no group-level changes were observed in TA, retreat participants' TA levels at post-assessment were inversely related to several indices of retreat engagement and prior meditation experience. Neuroticism also predicted variation in TA across retreat. These findings suggest that meditation training in a retreat setting may have positive effects on telomere regulation, which are moderated by individual differences in personality and meditation experience. (ClinicalTrials.gov #NCT03056105).

[The progress of studies on aqueous humor dynamics abnormality induced by trabecular meshwork and Schlemm canal endothelial cell senescence and its relation with glaucoma]

Glaucoma is the second leading cause of blindness in the world next to cataract. Aging is a strong risk factor leading to elevated intraocular pressure (IOP). IOP is associated with aqueous humor circulation. Trabecular meshwork cells and Schlemm canal endothelial cells, which form the conventional outflow pathway, play an important role in maintaining the IOP. Cell senescence induces abnormalities of the aqueous humor dynamics, leading to elevated IOP. Trabecular meshwork cells cause increased intrinsic stiffness, autophagy dysfunction, abnormal expression of microRNA and mitochondrial dysfunction with senescence. The senescence of Schlemm canal endothelial cells decreases cell permeability and mechanotransduction and disrupts the endothelial nitric oxide synthase signaling pathway. The changes will increase aqueous humor outflow resistance and elevate IOP. This review discusses how cell senescence induces aqueous humor dynamics abnormalities and the relation with glaucoma. (Chin J Ophthalmol, 2017, 53: 868-873).

[Cellular senescence and colorectal cancer]

Apart from proliferation and cell death, cellular senescence is an important response to numerous stress-associated stimuli. Originally described as an in vitro phenomenon, it is involved in various physiological and pathophysiological processes. For example, during the development of solid and generalized tumors, senescence induction poses an important barrier against disease progression. This could be demonstrated for malignant lymphomas, melanomas and various carcinomas using sophisticated animal models. However, senescent cells remain highly secretorically active and have a profound effect on neighboring cells as well as the entire tissue network. This article tries to provide insight into the current literature and discusses clinical implications and future applications.

[Gene expression profiles of long non-coding RNAs in human degenerated intervertebral disc tissue]

Objective: To investigate the gene expression profiles of long non-coding RNAs (lncRNA)in human degenerated intervertebral disc degeneration (IDD). Methods: An lncRNA-mRNA microarray analysis of human nucleus pulposus (NP) was employed. Bioinformatics prediction was also applied to delineate the functional roles of the differentially expressed lncRNAs. Several lncRNAs and mRNAs were chosen for quantitative real-time PCR (qRT-PCR) validation. Results: A total of 1 570 lncRNAs expressed in degenerate group compared with the nondegenerate group. Of these, the expression level of 428 lncRNAs was upregulated >2-fold compared with nondegenerate group while that of 584 was downregulated. Bioinformatics analysis (GO and pathway analyses) revealed that some classical pathways participating in extracellular matrix (ECM) and cell apoptosis were aberrantly expressed in the intervertebral disc (P<0.05). Enhancer-like lncRNAs and their nearby coding genes were analyzed. Three lncRNAs were identified as potential enhancers. Several lncRNAs were validated in the intervertebral disc using RT-qPCR. Conclusion: The lncRNAs express differentially in the intervertebral disc. LncRNAs may therefore be novel candidate biomarkers and potential targets for intervertebral disc degeneration therapy in the future.

Physical activity and telomere length in U.S. men and women: An NHANES investigation

The principal objective was to determine the extent to which physical activity (PA) accounts for differences in leukocyte telomere length (LTL) in a large random sample of U.S. adults. Another purpose was to assess the extent to which multiple demographic and lifestyle covariates affect the relationship between PA and LTL. A total of 5823 adults from the National Health and Nutrition Examination Survey (NHANES 1999-2002) were studied cross-sectionally. Employing the quantitative polymerase chain reaction method, LTL was compared to standard reference DNA. PA was indexed using MET-minutes using self-reported frequency, intensity, and duration of participation in 62 physical activities. Covariates were controlled statistically. Telomeres were 15.6 base pairs shorter for each year of chronological age (F=723.2, P<0.0001). PA was inversely related to LTL after adjusting for all the covariates (F=8.3, P=0.0004). Telomere base pair differences between adults with High activity and those in the Sedentary, Low, and Moderate groups were 140, 137, and 111, respectively. Adults with High activity were estimated to have a biologic aging advantage of 9years (140 base pairs÷15.6) over Sedentary adults. The difference in cell aging between those with High and Low activity was also significant, 8.8years, as was the difference between those with High and Moderate PA (7.1years). Overall, PA was significantly and meaningfully associated with telomere length in U.S. men and women. Evidently, adults who participate in high levels of PA tend to have longer telomeres, accounting for years of reduced cellular aging compared to their more sedentary counterparts.

Influences of age-related changes in mesenchymal stem cells on macrophages during in-vitro culture

BACKGROUND

Mesenchymal stem cells (MSCs) have been widely used in cytotherapy and tissue engineering due to their immunosuppressive ability and regenerative potential. Recently, the immunomodulatory influence of MSCs has been gaining increasing attention because their functional roles in modulating immune responses likely have high clinical significance.

METHODS

In this study, we investigated the influence of MSCs on macrophages (Mφs) in in-vitro cell culture systems. Given evidence that aged MSCs are functionally compromised, bone marrow-derived MSCs (BMSCs) isolated from both young and aged mice (YMSCs and AMSCs) were evaluated and contrasted.

RESULTS

We found that YMSCs exhibited greater proliferative and osteo-differentiation potential compared to AMSCs. When cocultured with RAW264.7 cells (an Mφ cell line), both YMSCs and AMSCs coaxed polarization of Mφs toward an M2 phenotype and induced secretion of anti-inflammatory and immunomodulatory cytokines. Compared to AMSCs, YMSCs exhibited a more potent immunomodulatory effect. While Mφs cocultured with either YMSCs or AMSCs displayed similar phagocytic ability, AMSC coculture was found to enhance Mφ migration in Transwell systems. When BMSCs were prestimulated with interferon gamma before coculture with RAW264.7 cells, their regulatory effects on Mφs appeared to be modified. Here, compared to stimulated AMSCs, stimulated YMSCs also exhibited enhanced cellular influence on cocultured RAW264.7 cells.

CONCLUSIONS

Our data suggest that BMSCs exert an age-related regulatory effect on Mφs with respect to their phenotype and functions but an optimized stimulation to enhance MSC immunomodulation is in need of further investigation.

Native and solubilized decellularized extracellular matrix: A critical assessment of their potential for improving the expansion of mesenchymal stem cells

Capturing the promise of mesenchymal stem cell (MSC)-based treatments is currently limited by inefficient production of cells needed for clinical therapies. During conventional ex vivo expansion, a large portion of MSCs lose the properties that make them attractive for use in cell therapies. Decellularized extracellular matrix (dECM) has recently emerged as a promising substrate for the improved expansion of MSCs. MSCs cultured on these surfaces exhibit improved proliferation capacity, maintenance of phenotype, and increased differentiation potential. Additionally, these dECMs can be solubilized and used to coat new cell culture surfaces, imparting key biological properties of the native matrices to other surfaces such as tissue engineering scaffolds. Although this technology is still developing, there is potential for an impact in the fields of MSC biology, biomaterials, tissue engineering, and therapeutics. In this article, we review the role of dECM in MSC expansion by first detailing the decellularization methods that have been used to produce the dECM substrates; discussing the shortcomings of current decellularization methods; describing the improved MSC characteristics obtained when the cells are cultured on these surfaces; and considering the effect of the passage number, age of donor, and dECM preparation method on the quality of the dECM. Finally we describe the critical roadblocks that must be addressed before this technology can fulfil its potential, including elucidating the mechanism by which the dECMs improve the expansion of primary MSCs and the identification of a readily available source of dECM.

STATEMENT OF SIGNIFICANCE

Current mesenchymal stem cell (MSC) culture methods result in premature cellular senescence or loss of differentiation potential. This creates a major bottleneck in their clinical application, as prolonged expansion is necessary to achieve clinically relevant numbers of cells. Recently, decellularized extracellular matrix (dECM) produced by primary MSC has emerged as an attractive substrate for the improved expansion of MSC; cells cultured on these surfaces retain their desired stem cell characteristics for prolonged times during culture. This review article describes the inception and development of this dECM-based technology, points out existing challenges that must be addressed, and suggests future directions of research. To our knowledge, this is the first review written on the use of dECM for improved mesenchymal stem cell expansion.

[Expression of signaling pathway of mammalian target of rapamycin in articular cartilage cell induced by interleukin 1β]

Objective: To observe effect of interleukin(IL)-1β on the expression of signaling pathway of mammalian target of rapamycin(mTOR) of articular cartilage. Methods: Articular cartilage of rats was isolated under sterile technique, cells were digested by type Ⅱ collagenase and trypsin and cultured in vitro, pre-culture the Ⅱ cells for three days, different concentrations of IL-1β were added for 24 hours.The cells were stained with toluidine blue and HE, to observe morphological changes of cells.RT-PCR was used to detect the mRNA expression of typeⅡcollagen gene, aggrecan gene, mTOR gene and P70S6K gene, Western blotting was used to detect the expression of protein related to mTOR. Results: With increasing concentrations of IL-1β, the phenotype of cells appeared polygon into a spindle, the mRNA expression of gene of type Ⅱ collagen (the control group: 0.821±0.014; 1 ng/ml: 0.614±0.014; 10 ng/ml: 0.549±0.009; 100 ng/ml: 0.520±0.008), aggrecan(0.867±0.005; 0.857±0.001; 0.554±0.008; 0.538±0.004) and mTOR(0.845±0.015; 0.785±0.009; 0.569±0.025; 0.518±0.014) reduced, but P70S6K(0.465±0.024; 0.566±0.022; 0.663±0.022; 0.896±0.015) increased by PCR .Expression of protein detected by Western blotting was similar to the trend of PCR. Conclusion: mTOR signaling pathway may play an important role on the degeneration of articular cartilage, regulating mTOR signaling pathway may provides a new idea of delaying the degeneration process of cells.

Caffeine consumption and telomere length in men and women of the National Health and Nutrition Examination Survey (NHANES)

BACKGROUND

The investigation evaluated the relationship between caffeine intake and coffee consumption and leukocyte telomere length, a biomarker of the senescence of cells.

METHODS

A total of 5826 adults from the National Health and Nutrition Examination Survey (NHANES) were studied cross-sectionally. Using the quantitative polymerase chain reaction method, telomere length was compared to standard reference DNA. Caffeine intake from foods and beverages and coffee consumption were measured using a validated, multi-pass, computer-assisted, 24-h recall system administered by NHANES interviewers. The following covariates were controlled: age, gender, race, marital status, education, housing, smoking, BMI, physical activity, alcohol use, and coffee intake (or caffeine consumption).

RESULTS

Caffeine consumption was inversely related to telomere length (F = 15.1, P = 0.0005). For each 100 mg of caffeine consumed, telomeres were 35.4 base pairs shorter, after adjusting for the covariates. For each 100 mg of caffeine consumed among coffee drinkers only, telomeres were 36.7 base pairs shorter (F = 9.0, P = 0.0054), and among non-coffee drinkers only, 40.0 base pairs shorter (F = 8.5, P = 0.0067). Conversely, coffee intake was positively related to telomere length (F = 12.6, P = 0.0013), independent of the covariates.

CONCLUSIONS

Results suggest that caffeine consumption accounts for shorter telomeres in U.S. adults, independent of numerous covariates, whereas coffee intake predicts longer telomeres.

[Changes of the expression for genes related with senescence and the telomerase activity during cellular replicative and premature senescence in human embryonic lung fibroblasts]

Objective: To detect the alterations of telomerase activity and the expression for oxidative stress responsive genes related with senescence during cellular replicative senescence and hydrogen peroxide-induced premature senescence in human embryonic lung fibroblasts (HELFs) in vitro. Methods: The HELFs were divided into young cells (22 population doubling levels, 22PDL) , mid-aged cells (35PDL) and replicative senes-cent cells (49PDL) and premature senescent cells induced by H(2)O(2)(premature senescence, PS). The telomerase activity was detected by ELISA assay during cellular replicative and premature senescence. The mRNA level of oxidative stress responsive genes related with senescence for Foxo1, Foxo3, Pdx1, apoA-I and MMP1 was per-formed by RT-Q-PCR separately. Results: The mRNA level for Foxo1, Foxo3, apoA-I and Pdx1 was decreased separately during cellular replicative senescence compared to that in the young-stage cells with statistical signifi-cance (P<0.05). The expression of MMP1 was up-regulated 5.1-fold obviously (P<0.05). In premature senes-cence, the mRNA level was only decreased for Foxo1, Foxo3 and apoA-I, but up-regulated 2.3-fold and 6.2-fold for Pdx1 and MMP1 respcetively vs 22PDL significantly (P<0.05). The telomerase activity in young cells was not detected, and it increased in mid-aged cells and replicative senescence stages during cellular replicative se-nescence as compared to 22PDL with statistical significance (P<0.05). The telomerase activity in premature se-nescence was highly active. Conclusion: The expression for genes related with senescence has differences be-tween replicative and premature senescence and hydrogen peroxide modifies their expression levels. The telomer-ase activity has been going up with increased PDLs.

Consumption of Nuts and Seeds and Telomere Length in 5,582 Men and Women of the National Health and Nutrition Examination Survey (NHANES)

OBJECTIVES

Consumption of nuts and seeds is associated favorably with all-cause mortality. Nuts and seeds could reduce disease and prolong life by influencing telomeres. Telomere length is a good indicator of the senescence of cells. The purpose of the present study was to determine the relationship between nuts and seeds intake and leukocyte telomere length, a biomarker of biologic aging.

DESIGN

Cross-sectional.

SETTING AND PARTICIPANTS

A total of 5,582 randomly selected men and women from the National Health and Nutrition Examination Survey (NHANES), 1999-2002, were studied.

MEASUREMENTS

DNA was obtained via blood samples. Telomere length was assessed using the quantitative polymerase chain reaction method. A validated, multi-pass, 24-h recall dietary assessment, administered by NHANES, was employed to quantify consumption of nuts and seeds.

RESULTS

Nuts and seeds intake was positively and linearly associated with telomere length. For each 1-percent of total energy derived from nuts and seeds, telomere length was 5 base pairs longer (F=8.6, P=0.0065). Given the age-related rate of telomere shortening was 15.4 base pairs per year (F=581.1, P<0.0001), adults of the same age had more than 1.5 years of reduced cell aging if they consumed 5% of their total energy from nuts and seeds.

CONCLUSIONS

Consumption of nuts and seeds accounts for meaningful decreases in biologic aging and cell senescence. The findings reinforce the recommendations of the 2015-2020 Dietary Guidelines for Americans, which encourage the consumption of nuts and seeds as part of a healthy diet.

Pretreatment of Ferulic Acid Protects Human Dermal Fibroblasts against Ultraviolet A Irradiation

Background

Approximately 90%~99% of ultraviolet A (UVA) ray reaches the Earth's surface. The deeply penetrating UVA rays induce the formation of reactive oxygen species (ROS), which results in oxidative stress such as photoproducts, senescence, and cell death. Thus, UVA is considered a primary factor that promotes skin aging.

Objective

Researchers investigated whether pretreatment with ferulic acid protects human dermal fibroblasts (HDFs) against UVA-induced cell damages.

Methods

HDF proliferation was analyzed using the water-soluble tetrazolium salt assay. Cell cycle distribution and intracellular ROS levels were assessed by flow cytometric analysis. Senescence was evaluated using a senescence-associated β-galactosidase assay, while Gadd45α promoter activity was analyzed through a luciferase assay. The expression levels of superoxide dismutase 1 (SOD1), catalase (CAT), xeroderma pigmentosum complementation group A and C, matrix metalloproteinase 1 and 3, as well as p21 and p16 were measured using quantitative real-time polymerase chain reaction.

Results

Inhibition of proliferation and cell cycle arrest were detected in cells that were irradiated with UVA only. Pretreatment with ferulic acid significantly increased the proliferation and cell cycle progression in HDFs. Moreover, ferulic acid pretreatment produced antioxidant effects such as reduced DCF intensity, and affected SOD1 and CAT mRNA expression. These effects were also demonstrated in the analysis of cell senescence, promoter activity, expression of senescent markers, and DNA repair.

Conclusion

These results demonstrate that ferulic acid exerts protective effects on UVA-induced cell damages via anti-oxidant and stress-inducible cellular mechanisms in HDFs.

Characterization of Senescence of Culture-expanded Human Adipose-derived Mesenchymal Stem Cells

Background and Objectives

Adipose-derived mesenchymal stem cells (ADSCs) are promising candidates in regenerative medicine. The need for in vitro propagation to obtain therapeutic quantities of the cells imposes a risk of impaired functionality due to cellular senescence. The aim of the study was to analyze in vitro senescence of previously cryopreserved human ADSCs subjected to serial passages in cell culture.

Methods and Results

ADSC cultures from 8 donors were cultivated until proliferation arrest was reached. A gradual decline of ADSC fitness was observed by altered cell morphology, loss of proliferative, clonogenic and differentiation abilities and increased β-galactosidase expression all of which occurred in a donor-specific manner. Relative telomere length (RTL) analysis revealed that only three tested cultures encountered replicative senescence. The presence of two ADSC subsets with significantly different RTL and cell size was discovered. The heterogeneity of ADSC cultures was supported by the intermittent nature of aging seen in tested samples.

Conclusions

We conclude that the onset of in vitro senescence of ADSCs is a strongly donor-specific process which is complicated by the intricate dynamics of cell subsets present in ADSC population. This complexity needs to be carefully considered when elaborating protocols for personalized cellular therapy.

Progerin, the protein responsible for the Hutchinson-Gilford progeria syndrome, increases the unrepaired DNA damages following exposure to ionizing radiation

Introduction

Progerin, the protein responsible for the Hutchinson-Gilford Progeria Syndrome (HGPS), is a partially deleted form of nuclear lamin A, and its expression has been suggested as a cause for dysfunctional nuclear membrane and premature senescence. To examine the role of nuclear envelop architecture in regulating cellular aging and DNA repair, we used ionizing radiation to increase the number of DNA double strand breaks (DSBs) in normal and HGPS cells, and analyzed possible relationship between unrepaired DSBs and cellular aging.

Results

We found that HGPS cells are normal in repairing a major fraction of radiation-induced double strand breaks (M-DSBs)but abnormal to show increased amount of residual unrepaired DSBs (R-DSBs). Such unrepaired DSBs were 2.6 times (CI 95 %: 2.2–3.2) higher than that in normal cells one week after the irradiation, and 1.6 times (CI 95 %: 1.3–1.9) higher even one month after the irradiation. These damages tend to increase as the nuclear envelope become abnormal, a characteristic of both HGPS and normal human cells which undergo replicative senescence. The artificial, enforced over-expression of progerin further impaired the repair of M-DSBs, implying lamin A-associated nuclear membrane has an important role for DNA DSB repair. Introduction of telomerase gene function in HGPS cells reversed such aging phenotypes along with upregulation of lamin B1 and downregulation of progerin, which is a hallmark of young cells.

Conclusion

We suggest that lamin A- or progerin-associated nuclear envelope is involved in cellular aging associated with DNA damage repair.

Electronic supplementary material

The online version of this article (doi:10.1186/s41021-015-0018-4) contains supplementary material, which is available to authorized users.

Senescent human hepatocytes express a unique secretory phenotype and promote macrophage migration

AIM: To develop a model of stress-induced senescence to study the hepatocyte senescence associated secretory phenotype (SASP).

METHODS: Hydrogen peroxide treatment was used to induce senescence in the human HepG2 hepatocyte cell line. Senescence was confirmed by cytochemical staining for a panel of markers including Ki67, p21, heterochromatin protein 1β, and senescence-associated-β-galactosidase activity. Senescent hepatocytes were characterised by gene expression arrays and quantitative polymerase chain reaction (qPCR), and conditioned media was used in proteomic analyses, a human chemokine protein array, and cell migration assays to characterise the composition and function of the hepatocyte SASP.

RESULTS: Senescent hepatocytes induced classical markers of senescence (p21, heterochromatin protein 1β, and senescence-associated-β-galactosidase activity); and downregulated the proliferation marker, Ki67. Hepatocyte senescence induced a 4.6-fold increase in total secreted protein (P = 0.06) without major alterations in the protein profile. Senescence-induced genes were identified by microarray (Benjamini Hochberg-corrected P < 0.05); and, consistent with the increase in secreted protein, gene ontology analysis revealed a significant enrichment of secreted proteins among inducible genes. The hepatocyte SASP included characteristic factors such as interleukin (IL)-8 and IL-6, as well as novel components such as SAA4, IL-32 and Fibrinogen, which were validated by qPCR and/or chemokine protein array. Senescent hepatocyte-conditioned medium elicited migration of inflammatory (granulocyte-macrophage colony stimulating factor, GM-CSF-derived), but not non-inflammatory (CSF-1-derived) human macrophages (P = 0.022), which could contribute to a pro-inflammatory microenvironment in vivo, or facilitate the clearance of senescent cells.

CONCLUSION: Our novel model of hepatocyte senescence provides insights into mechanisms by which senescent hepatocytes may promote chronic liver disease pathogenesis.

Cell Aging of Mouse Gastrointestinal Tract Observed by Light and Electron Microscopic Radioautography

The term "cell aging" initially means how the cells change due to their aging. There are two meanings, i.e. how a cell changes when it is isolated from original animals such as in vitro cells in cell culture, otherwise how all the cells of an animal change in vivo due to the aging of the individual animal. We have been studying the latter changes from the viewpoint of the cell nutrients, the precursors for the macromolecular synthesis such as deoxyribonucleic acid (DNA), ribonucleic acid (RNA), proteins, glucides and lipids, which are incorporated and synthesized into various cells of individual animals. Therefore, this article deals with only the cell aging of animal cells in vivo, how the metabolism, i.e. incorporations and syntheses of respective nutrient precursors in various kinds of cells change due to the aging of individual experimental animals such as mice by means of microscopic radioautography to localize the RI-labeled precursors. The incorporations and syntheses of various precursors for macromolecules such as DNA, RNA, proteins, glucides, lipids and others in various kinds of cells of various organs in the gastrointestinal tract such as the mouth, esophagus, stomach and intestines are reviewed referring many original papers already published from our laboratory during these 60 years since the late 20th century.

Neighborhood characteristics and leukocyte telomere length: the Multi-Ethnic Study of Atherosclerosis

Telomeres are the protective caps at the ends of eukaryotic chromosomes. Telomeres get shorter each time a cell divides, and critically shortened telomeres trigger cellular senescence. Thus, telomere length is hypothesized to be a biological marker of aging. The purpose of this study was to examine the association between neighborhood characteristics and leukocyte telomere length. Using data from a subsample (n=978) of the Multi-Ethnic Study of Atherosclerosis, a population-based study of women and men aged 45-84, we found that neighborhood social environment (but not neighborhood socioeconomic disadvantage) was associated with telomere length. Respondents who lived in neighborhoods characterized by lower aesthetic quality, safety, and social cohesion had shorter telomeres than those who lived in neighborhoods with a more salutary social environment, even after adjusting for individual-level socioeconomic status and biomedical and lifestyle factors related to telomere length. Telomere length may be one biological mechanism by which neighborhood characteristics influence an individual׳s risk of disease and death.

Glycogen Synthase Kinase 3 Inactivation Induces Cell Senescence through Sterol Regulatory Element Binding Protein 1-Mediated Lipogenesis in Chang Cells

BACKGROUND

Enhanced lipogenesis plays a critical role in cell senescence via induction of expression of the mature form of sterol regulatory element binding protein 1 (SREBP1), which contributes to an increase in organellar mass, one of the indicators of senescence. We investigated the molecular mechanisms by which signaling molecules control SREBP1-mediated lipogenesis and senescence.

METHODS

We developed cellular models for stress-induced senescence, by exposing Chang cells, which are immortalized human liver cells, to subcytotoxic concentrations (200 µM) of deferoxamine (DFO) and H2O2.

RESULTS

In this model of stress-induced cell senescence using DFO and H2O2, the phosphorylation profile of glycogen synthase kinase 3α (GSK3α) and β corresponded closely to the expression profile of the mature form of SREBP-1 protein. Inhibition of GSK3 with a subcytotoxic concentration of the selective GSK3 inhibitor SB415286 significantly increased mature SREBP1 expression, as well as lipogenesis and organellar mass. In addition, GSK3 inhibition was sufficient to induce senescence in Chang cells. Suppression of GSK3 expression with siRNAs specific to GSK3α and β also increased mature SREBP1 expression and induced senescence. Finally, blocking lipogenesis with fatty acid synthase inhibitors (cerulenin and C75) and siRNA-mediated silencing of SREBP1 and ATP citrate lyase (ACL) significantly attenuated GSK3 inhibition-induced senescence.

CONCLUSION

GSK3 inactivation is an important upstream event that induces SREBP1-mediated lipogenesis and consequent cell senescence.

Multisystem resiliency moderates the major depression-telomere length association: findings from the Heart and Soul Study

Major depressive disorder (MDD) has been associated with reduced leukocyte telomere length (LTL). It is not known, however, whether psychosocial and behavioral protective factors moderate this association. In the current study, we examine whether multisystem resiliency--defined by healthy emotion regulation, strong social connections, and health behaviors (sleep and exercise)--predicts LTL and mitigates previously demonstrated associations between depression diagnosis and LTL. LTL was measured, using a quantitative PCR assay, in 954 patients with stable cardiovascular disease in the Heart and Soul Study. In a fully adjusted model, high multisystem resiliency predicted longer LTL (b=80.00, SE=27.17, p=.003), whereas each individual factor did not. Multisystem resiliency significantly moderated the MDD-LTL association (p=.02). Specifically, MDD was significantly related to LTL at 1 SD below the mean of multisystem resiliency (b=-142.86, SE=56.46, p=.01), but not at 1 SD above the mean (b=49.07, SE=74.51, p=.51). This study suggests that MDD associations with biological outcomes should be examined within a psychosocial-behavioral context, because this context shapes the nature of the direct relationship. Further research should explore the cognitive, neural, and other physiological pathways through which multisystem resiliency may confer biological benefit.

The role of cellular senescence in the gastrointestinal mucosa

Cellular senescence is a biologically irreversible state of cell-growth arrest that occurs following either a replicative or an oncogenic stimulus. This phenomenon occurs as a response to the presence of premalignant cells and appears to be an important anticancer mechanism that keeps these transformed cells at bay. Many exogenous and endogenous triggers for senescence have been recognized to act via genomic or epigenomic pathways. The most common stimulus for senescence is progressive loss of telomeric DNA, which results in the loss of chromosomal stability and eventual unregulated growth and malignancy. Senescence is activated through an interaction between the p16 and p53 tumor-suppressor genes. Senescent cells can be identified in vitro because they express senescence-associated β-galactosidase, a marker of increased lysosomal activity. Cellular senescence plays an integral role in the prevention and development of both benign and malignant gastrointestinal diseases. The senescence cascade and the cell-cycle checkpoints that dictate the progression and maintenance of senescence are important in all types of gastrointestinal cancers, including pancreatic, liver, gastric, colon, and esophageal cancers. Understanding the pathogenic mechanisms involved in cellular senescence is important for the development of agents targeted toward the treatment of gastrointestinal tumors.