Dopaminergic mediation in the brain aging and neurodegenerative diseases:a role of senescent cells

Aging is well known to be the main risk factor for the neurodegenerative pathologies,in particular,Parkinson’s disease（PD）and Alzheimer’s disease（AD）.In aging and in the diseases,similar changes in various hallmarks of neurodegeneration（lipofuscin accumulation,autophagia weakening,and disturbances in functions of mitochondriaand lysosomes） were shown （Tan et al., 2014）. Furthermore, dopami- nergic system （DAS） involvement in mechanisms of aging, PD, and AD were revealed （Martorana and Koch, 2014）.

Strategies to improve regenerative potential of mesenchymal stem cells

In the last few decades,stem cell-based therapies have gained attention worldwide for various diseases and disorders.Adult stem cells,particularly mesenchymal stem cells(MSCs),are preferred due to their significant regenerative potential in cellular therapies and are currently involved in hundreds of clinical trials.Although MSCs have high self-renewal as well as differentiation potential,such abilities are compromised with“advanced age”and“disease status”of the donor.Similarly,cell-based therapies require high cell number for clinical applications that often require in vitro expansion of cells.It is pertinent to note that aged individuals are the main segment of population for stem cell-based therapies,however;autologous use of stem cells for such patients(aged and diseased)does not seem to give optimal results due to their compromised potential.In vitro expansion to obtain large numbers of cells also negatively affects the regenerative potential of MSCs.It is therefore essential to improve the regenerative potential of stem cells compromised due to“in vitro expansion”,“donor age”and“donor disease status”for their successful autologous use.The current review has been organized to address the age and disease depleted function of resident adult stem cells,and the strategies to improve their potential.To combat the problem of decline in the regenerative potential of cells,this review focuses on the strategies that manipulate the cell environment such as hypoxia,heat shock,caloric restriction and preconditioning with different factors.

Effect of cholecystokinin on experimental neuronal aging

AIM: To observe the effect of cholecystokinin (CCK) on lipofusin value, neuronal dendrite and spine ultrastructure, and total cellular protein during the process of experimental neuronal aging. METHODS: Experimental neuronal aging study model was established by NBA2 cellular serum-free culture method. By using single intracellular lipofusin value from microspectrophotometry, morphology of neuronal dendrites and spines from the scanner electron microscopy, and total cellular protein as the indexes of experimental neuronal aging, we observed the effect of CCKs on the process of experimental neuronal aging. RESULTS: Under the condition of serum-free culture, intracellular fluorescence value (%) increased with the extension of culture time (1 d 8.51±3.43; 5 d 10.12±3.03; 10 d 20.54±10.3; 15 d 36.88±10.49; bP<0.01). When CCK was added to serum-free culture medium, intracellular lipofusin value (%) decreased remarkably after consecutive CCK reaction for 10 and 15 d (control 36.88±10.49; 5 d 32.03±10.01; 10 d 14.37±5.55; 15 d 17.31±4.80; bP<0.01). As the time of serum-free culturing was prolonged, the number of neuronal dendrite and spine cells decreased. The later increased in number when CCK8 was added. CCK8 could improve the total cellular protein in the process of experimental neuronal aging. CONCLUSION: CCKs may prolong the process of experimental neuronal aging by maintaining the structure and the number of neuronal dendrite and spine cells and changing the total cellular protein.

Effect of pseudolaric acid B on gastric cancer cells: Inhibition of proliferation and induction of apoptosis

AIM: To examine the effect of pseudolaric acid B on the growth of human gastric cancer cell line, AGS, and its possible mechanism of action.METHODS: Growth inhibition by pseudolaric acid B was analyzed using MTT assay. Apoptotic cells were detected using Hoechst 33258 staining, and confirmed by DNA fragmentation analysis. Western blot was used to detect the expression of apoptosis-regulated gene Bcl-2, caspase 3, and cleavage of poly (ADP-ribose)polymerase-1 (PARP-1).RESULTS: Pseudolaric acid B inhibited the growth of AGS cells in a time- and dose-dependent manner by arresting the cells at G2/M phase, which was accompanied with a decrease in the levels of cdc2.AGS cells treated with pseudolaric acid B showed typical characteristics of apoptosis including chromatin condensation and DNA fragmentation. Moreover,treatment of AGS cells with pseudolaric acid B was also associated with decreased levels of the anti-apoptotic protein Bcl-2, activation of caspase-3, and proteolytic cleavage of PARP-1.CONCLUSION: Pseudolaric acid B can dramatically suppress the AGS cell growth by inducing apoptosis after G2/M phase arrest. These findings are consistent with the possibility that G2/M phase arrest is mediated by the down-regulation of cdc2 levels. The data also suggest that pseudolaric acid B can trigger apoptosis by decreasing Bcl-2 levels and activating caspase-3 protease.

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).

Effect of NaCI and Helicobacter pylori vacuolating cytotoxin on cytokine expression and viability

AIM; To determine whether Helicobacter pylori （H pylon） vacuolating cytotoxin （VacA） regulates release of proinflammatory cytokines （IL-1β, IL-8, TNF-α, and IL-6） or alters gastric epithelial cell viability and to determine whether NaCl affects these VacA-induced changes. METHODS： Vacuolating activity was determined by measuring the uptake of neutral red into vacuoles of VacA-treated human gastric epithelial （AGS） cells. AGS cell viability was assessed by direct cell counting. Specific enzyme-linked immunosorbent assays （ELISA） and reverse transcdptase-polymerase chain reaction（RT-PCR） were performed to examine the effects of H pylori VacA and NaCl on cell pro-inflammatory cytokine production in AGS cells. Immunohistochemical staining of gastric tissue from Mongolian gerbils was used to confirm VacAinduced pro-inflammatory cytokine production and the effects of NaCl on this VacA-induced response. RESULTS： Addition of VacA alone reduced AGS cell viability （P〈 0.05）, and this reduction was enhanced by high doses of NaCl （P〈0.05）. VacA alone induced expression of TNF-α, IL-8 and IL-1β, while NaCl alone induced expression of TNF-α and IL-1β. Changes in mRNA levels in the presence of both VacA and NaCl were more complicated. For the case of TNF-α, expression was dosedependent on NaCl. IL-6 mRNA was not detected. However, low levels of IL-6 were detected by EUSA. Positive immunohistochemical staining of IL-1, IL-6, and TNF-α was found in gastric tissue of H pylori-infected gerbils fed with either a normal diet or a high salt diet. However, the staining of these three cytoldnes was sb＇onger in H pylori-infected animals fed with a 5g/kg NaCl diet. CONCLUSION： VacA decreases the viability of AGS cells, and this effect can be enhanced by NaCl. NaCl also affects the production of pro-inflammatory cytokines in- duced by VacA, suggesting that NaCl plays an important role in Hpylori-induced gastric epithelial cell cytotoxicity.

mRNA levels of TLR4 and TLR5 are independent of H pylori

AIM:To determine if the presence H pylori or its viru- lence affect toll-like receptor 4 (TLR4) and TLR5 mRNA expression levels. METHODS:For the in vivo assays, gastric biopsies were obtained from 40 patients and H pylori status was determined. For the in vitro assays, human gastric adenocarcinoma mucosal cells (AGS) were cultured in the presence or absence of twelve selected H pylori strains. H pylori strains isolated from culture-positive patients and selected strains were genotyped for cagA and vacA. The cDNA was obtained from mRNA extracted from biopsies and from infected AGS cells. TLR4 and TLR5 mRNA levels were examined by real-time PCR. RESULTS: The presence of H pylori did not affect the mRNA levels of TLR4 or TLR5 in gastric biopsies. The mRNA levels of both receptors were not influenced by the vacA status (P > 0.05 for both receptors) andthere were no differences in TLR4 or TLR5 mRNA levels among the different clinical presentations/histological fi ndings (P > 0.05). In the in vitro assay, the mRNA levels of TLR4 or TLR5 in AGS cells were not influenced by the vacAs1 status or the clinical condition as-sociated with the strains (P > 0.05 for both TLR4 and TLR5). CONCLUSION: The results of this study show that the mRNA levels of TLR4 and TLR5 in gastric cells, both in vivo and in vitro, are independent of H pylori colonization and suggest that vacA may not be a significant player in the first step of innate immune recognition mediated by TLR4 or TLR5.

Inflammation and hematopoietic stem cells aging

Hematopoietic stem cells(HSCs)replenish all lineages of blood cells throughout the lifespan.During aging,the repopulation capacity of HSCs declined,and aged HSCs display a tendency for myeloid differentiation.Several intrinsic and extrinsic factors have been identified to promote HSCs aging.In this review,we focus on the contribution of aging-associated inflammation in provoking HSCs aging and discuss the future research direction of inflammation and HSC aging.

Epstein-Barr virus induces human nasopharyngeal epithelial cells to escape from the replicative senescence

OBJECTIVE: To observe the biological changes of primary human nasopharyngeal epithelial cells in the early stage of immortalization. METHODS: The morphological changes of nasopharyngeal epithelial cells were observed by phase contrast microscopy, and the activity profile of senescence-associated beta-galactosidase (SA-beta-Gal) was detected by SA-beta-Gal staining. The expression of p16(INK4a) protein was tested by immunochemical assay, and the life span in vitro of nasopharyngeal epithelial cells was calculated as population doublings. In addition, the expression of Epstein-Barr (EB) virus latent membrane protein 1 (LMP1) was also detected by immunofluorescence staining. RESULTS: Morphologically, cells treated with EB virus and 12-o-tetradecanoyl-phorbol-13-acetate (TPA) formed multi-layer foci, and their cellular life span in vitro was extended (about 155 days of culture). A low percentage of cells (about 4.8%) expressed SA-beta-Gal activity at late primary culture, and did not always express p16(INK4a) protein in the progression of culture. CONCLUSIONS: Nasopharyngeal epithelial cells treated with EB virus in cooperation with TPA can pass through the stage of senescence and enter the early stage of immortalization. Some changes of phenotype occur in these cells.Our results provide data for further studying the mechanism of immortalization and the establishment of a human nasopharyngeal epithelial cell line.

Thymosin Beta-4 Recombinant Adeno-associated Virus Enhances Human Nucleus Pulposus Cell Proliferation and Reduces Cell Apoptosis and Senescence

Background： Thymosin beta-4 （TB-4） is considered key roles in tissue development, maintenance and pathological processes. The study aimed to prove TB-4 positive biological function on nucleus pulposus （NP） cell apoptosis and slowing the process of cell aging while increasing the cell proliferation. Methods： TB-4 recombinant adeno-associated virus （AAV） was constructed and induced to human NP cells. Cell of same group were cultured without gene modification as controlled group. Proliferation capacity and cell apoptosis were observed during 6 passages of the cells. Morphology and expression of the TB-4 gene were documented as parameter of cell activity during cell passage. Results： NP cells with TB-4 transfection has normal TB-4 expression and exocytosis. NP cells with TB-4 transfection performed significantly higher cell activity than that at the control group in each generation. TB-4 recombinant AAV-transfected human NP cells also show slower cell aging, lower cell apoptosis and higher cell proliferation than control group. Conclusions： TB-4 can prevent NP cell apoptosis, slow NP cell aging and promote NP cell proliferation. AAV transfection technique was able to highly and stably express TB-4 in human NP cells, which may provide a new pathway for innovation in the treatment of intervertebral disc degenerative diseases.

Extract from Zanthoxylum piperitum Induces Apoptosis of AGS Gastric Cancer Cells through Akt/MDM2/p53 Signaling Pathway

Objective:To determine the effect of Zanthoxylum piperitum extracet(ZPE)on apoptosis and analyze anticancer substances in ZPE,changes in proteins related to apoptosis,and pathological changes in tumors in mouse.Methods:Fifteen 4-week-old female BALB/c nu/nu mice were divided into 3 groups depending on ZPE dose,with 5 in each group.AGS gastric carcinoma cells(1 x 10^(6) cells/200 jxL)were subcutaneously injected into the flank of each mouse.One week after the injection of AGS cells,ZPE was administered to the skin tissue[10 or 50 mg/(kg-d)]in the low-and high-dose groups,respectively for 20 days.Control animals were injected with vehicle only.After 3 weeks,the tumor was extracted and carried out for immunohistochemistry,the tendency of apoptosis and p53 in the body was checked using TdT-mediated dUTP nick-end labeling(TUNEL)assay.For 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assay,annexin V dead cell staining,cell cycle arrest and Western blotting,AGS gastric carcinoma cells were incubated with various concentrations of ZPE for 24 h.Cell survival rates were analyzed by MTT assays.Apoptosis was analyzed using annexin V dead cell staining and cell cycle arrest and measured using Muse cell analyzer.Results:High performance liquid chromatography(HPLC)analysis showed that ZPE contained organic sulfur compounds such as alliin and S-allylcysteine.MTT assay results revealed that ZPE(10-85»xg/mL)could effectively inhibit the growth of AGS gastric cancer cells at higher concentrations(P<0.05,P<0.01).The annexin V&dead cell staining assay and cell cycle arrest assay confirmed a dose-dependent increase in the apoptosis rate and G!phase in ZPE(10-70 jig/mL)groups.ZPE decreased the expression of anti-apoptotic proteins(p-Akt,p-MDM2,Bcl-2),while increased pro-apoptotic proteins(cleaved PARP,p53,pro-Caspase 3,Bax).TUNEL assays revealed an increase in cell apoptosis.Immunohistochemistry staining confirmed the involvement of p53.Conclusion:ZPE decreases AGS cell proliferation and induces apoptosis by inhibiting Akt and MDM2 expression.

DNA Damage Response in Hematopoietic Stem Cell Ageing

Maintenance of tissue-specific stem cells is vital for organ homeostasis and organismal longevity.Hematopoietic stem cells（HSCs） are the most primitive cell type in the hematopoietic system.They divide asymmetrically and give rise to daughter cells with HSC identity（selfrenewal） and progenitor progenies（differentiation）,which further proliferate and differentiate into full hematopoietic lineages.Mammalian ageing process is accompanied with abnormalities in the HSC self-renewal and differentiation.Transcriptional changes and epigenetic modulations have been implicated as the key regulators in HSC ageing process.The DNA damage response（DDR）in the cells involves an orchestrated signaling pathway,consisting of cell cycle regulation,cell death and senescence,transcriptional regulation,as well as chromatin remodeling.Recent studies employing DNA repair-deficient mouse models indicate that DDR could intrinsically and extrinsically regulate HSC maintenance and play important roles in tissue homeostasis of the hematopoietic system.In this review,we summarize the current understanding of how the DDR determines the HSC fates and finally contributes to organismal ageing.