Senescence Of Mesenchymal Stem Cells Research Articles

Extracellularly Detectable Electrochemical Signals of Living Cells Originate from Metabolic Reactions.

Direct detection of cellular redox signals has shown immense potential as a novel living cell analysis tool. However, the origin of such signals remains unknown, which hinders the widespread use of electrochemical methods for cellular research. In this study, the authors found that intracellular metabolic pathways that generate adenosine triphosphate (ATP) are the main contributors to extracellularly detectable electrochemical signals. This is achieved through the detection of living cells (4,706 cells/chip, linearity: 0.985) at a linear range of 7,466-48,866. Based on this discovery, the authors demonstrated that the cellular signals detected by differential pulse voltammetry (DPV) can be rapidly amplified with a developed medium containing metabolic activator cocktails (MACs). The DPV approach combined with MAC treatment shows a remarkable performance to detect the effects of the anticancer drug CPI-613 on cervical cancer both at a low drug concentration (2µm) and an extremely short treatment time (1hour). Furthermore, the senescence of mesenchymal stem cells could also be sensitively quantified using the DPV+MAC method even at a low passage number (P6). Collectively, their findings unveiled the origin of redox signals in living cells, which has important implications for the characterization of various cellular functions and behaviors using electrochemical approaches.

CAMP agonist forskolin disrupts mitochondrial metabolism and induces senescence in human mesenchymal cells.

Adult-derived mesenchymal stem cells (MSCs) can be used in therapies for the treatment of various diseases. MSCs derived from aging tissues or long-term MSC cultures could have diminished therapeutic effects compared with MSCs derived from younger tissues, but the underlying mechanism has not been completely established. Dysfunction of energy metabolism is one of the main mechanisms underlying cell senescence. Although cyclic adenosine monophosphate (cAMP) is known to inhibit cell division and proliferation in vitro, its impact on MSC senescence has not been described. In this study, we used forskolin, an adenylate cyclase agonist and cAMP inducer, to disrupt metabolism in human adipose-derived MSCs and investigate the effects of metabolic dysfunction on MSC senescence. Treatment of human MSCs with forskolin resulted in senescence phenotypes, including reduced proliferation, cell-cycle arrest, and enhanced expression of the cell aging markers p16 and p21. Furthermore, the senescent MSCs exhibited increased adipogenesis capacity and decreased osteogenesis capacity as well as a senescence-associated secretory phenotype characterized by increased expression of several inflammatory factors. Forskolin-associated MSC senescence was mainly caused by oxidative stress-induced disruption of mitochondrial metabolism, and the senescent MSCs had high levels of reactive oxygen species and reduced sirtuin gene expression. Lastly, we found that cAMP inhibitor SQ22536 protects MSCs from forskolin-induced senescence and senescence-related-inflammatory-phenotype (SASP). Our results indicate that forskolin can cause senescence of human MSCs through oxidative stress-induced mitochondrial metabolic dysfunction, and thus the results provide a basis for developing strategies for improving the quality and efficacy of cultured MSCs for clinical use.

C-Phycocyanin Ameliorates the Senescence of Mesenchymal Stem Cells through ZDHHC5-Mediated Autophagy via PI3K/AKT/mTOR Pathway.

The senescence of mesenchymal stem cells (MSCs) impairs their regenerative capacity to maintain tissue homeostasis. Numerous studies are focusing on the interventions and mechanisms to attenuate the senescence of MSCs. C-phycocyanin (C-PC) is reported to have multiple functions such as antitumor, antioxidation, anti-inflammation and anti-aging roles, but there is little research about the effects of C-PC on the senescence of MSCs. Here we investigated the roles and mechanism of C-PC on MSCs senescence. In vitro results showed that C-PC could reduce senescence, enhance proliferation, promote the adipogenic and osteogenic differentiation in senescent MSCs induced by oxidative stress. In vivo D-Galactose (D-Gal) induced rats aging models showed C-PC also increased the viability and differentiation of intrinsic senescent bone marrow derived MSCs (BMSCs). Furthermore, C-PC also decreased the levels of oxidative stress markers ROS or MDA, elevated the SOD activity, and increased the anti-inflammatory factors. Proteomic chip analysis showed that C-PC interacted with ZDHHC5, and their interaction was verified by pull down assay. Overexpression of ZDHHC5 aggravated the senescence of MSCs and greatly lessened the beneficial effects of C-PC on senescence. In addition, we found ZDHHC5 regulated autophagy by altering LC3, Beclin1 and PI3K/AKT/mTOR pathway. In summary, our data indicated that C-PC ameliorates the senescence of MSCs through zinc finger Asp-His-His-Cys (DHHC) domain-containing protein 5 (ZDHHC5) mediated autophagy via PI3K/AKT/mTOR pathway. The present study uncovered the key role of autophagy in MSCs senescence and PI3K/AKT/mTOR pathway may be a potential target for anti-senescence studies of MSCs.

Cordycepin Enhances SIRT1 Expression and Maintains Stemness of Human Mesenchymal Stem Cells.

Mesenchymal stem cells (MSCs) have been employed for therapeutic applications of various degenerative diseases. However, the major concern is MSC aging during the in vitro cultivation. Thus, the approach to delay MSC aging was examined in this research by focusing on the expression of Sirtuin 1 (SIRT1), a key anti-aging marker. Cordycepin, a bioactive compound derived from Cordyceps militaris, was used to up-regulate SIRT1 and maintain stemness of MSCs. Upon treatment with cordycepin, MSCs were investigated for cell viability, doubling time, key gene/protein expression, galactosidase-associated senescence assay, relative telomere length, and telomerase expression. Cordycepin significantly increased the expression of SIRT1 in MSCs by activating the adenosine monophosphate activated protein kinase (AMPK)-SIRT1 signalling pathway. Moreover, cordycepin maintained the stemness of MSCs by deacetylating SRY-box transcription factor 2 (SOX2) via SIRT1, and cordycepin delayed cellular senescence and aging of MSCs by enhancing autophagy, inhibiting the activity of senescence-associated-galactosidase, maintaining proliferation rate, and increasing telomere activity. Cordycepin could be used to increase SIRT1 expression in MSCs for anti-aging applications.

Mesenchymal Stem Cell Senescence during Aging:From Mechanisms to Rejuvenation Strategies.

In cell transplantation therapy, mesenchymal stem cells(MSCs)are ideal seed cells due to their easy acquisition and cultivation, strong regenerative capacity, multi-directional differentiation abilities, and immunomodulatory effects. Autologous MSCs are better applicable compared with allogeneic MSCs in clinical practice. The elderly are the main population for cell transplantation therapy, but as donor aging, MSCs in the tissue show aging-related changes. When the number of generations of in vitro expansion is increased, MSCs will also exhibit replicative senescence. The quantity and quality of MSCs decline during aging, which limits the efficacy of autologous MSCs transplantation therapy. In this review, we examine the changes in MSC senescence as a result of aging, discuss the progress of research on mechanisms and signalling pathways of MSC senescence, and discuss possible rejuvenation strategies of aged MSCs to combat senescence and enhance the health and therapeutic potential of MSCs.

In vitro characterization of umilical cord-dervied MSC's supplemented with PLAY®:A potential FBS substitute

Recent interest in the wound healing and regenerative properties of mesenchymal stem cells (MSCs) has prompted further investigation to elucidate their regenerative properties. Characterized by their ability to differentiate into various cell lineages, such as osteocytes, chondrocytes, and adipocytes, alongside promoting local angiogenesis and chemotaxis at the wound site, MSCs have proven to reduce the stipulated healing time. The myriad sources they originate from, including bone marrow and umbilical cord, underscore their wide range of clinical applicability. Extending the time for MSC senescence by using alternative media in a manner that preserves their stem-cell-like nature may be a viable option of achieving optimum cell numbers required for clinical protocols. Furthermore, various culture conditions have varied effects on MSCs, therefore, standardizing MSC growth conditions may help to produce MSCs with verified potency, which could be then extrapolated to clinical conditions. The presence of potential contaminants within commonly used cell culture media such as fetal bovine serum (FBS) curbs the scope of MSC implementation in tissue regeneration. Our current study aimed to continue to investigate the effects of blood derivative PLAY® on trends in MSC culture across various experimental parameters in comparison to FBS. Our results demonstrated that PLAY® consistently outperformed FBS across all the experimental metrics studied.

Rutin and quercetagetin enhance the regeneration potential of young and aging bone marrow-derived mesenchymal stem cells in the rat infarcted myocardium.

Myocardial infarction (MI) damages cardiomyocytes permanently and compromises cardiac function. Mesenchymal stem cells (MSCs) with the potential to differentiate into multiple lineages are considered as one of the best options for the treatment of MI. However, aging affects their regeneration capability. With age, reactive oxygen species (ROS) accumulate in cells ultimately causing cell death. To successfully utilize these stem cells in clinic, novel strategies to improve their functional capability should be explored. In this study, we aimed to enhance the cardiac regeneration potential of bone marrow MSCs derived from aging rats by treating them with antioxidants, rutin or quercetagetin in separate in vivo experiments. Oxidative stress was induced by treating MSCs of young and aging rats with different concentrations of H2O2 which resulted in an increase in the ROS level. MSCs were treated with rutin or quercetagetin at varying concentrations and exposed to H2O2. It was observed that both antioxidants significantly (P < 0.001) suppressed H2O2-induced intracellular ROS accumulation in a dose-dependent manner. An optimized concentration of 10µM rutin or quercetagetin was used for the in vivo experiments. MI models were developed in aging rats by ligation of left anterior descending artery and treated MSCs were transplanted in the MI models. Echocardiography was performed after 2 and 4weeks of cell transplantation to evaluate the functional status of the infarcted heart and histological analysis was performed after 4weeks to assess cardiac regeneration. Significant improvement was observed in cardiac parameters including LVEF% (P < 0.001), LVFS% (P < 0.01 and P < 0.001), LVIDd (P < 0.01 and P < 0.001), LVIDs (P < 0.001), LVEDV (P < 0.001) and LVESV (P < 0.001) in the treated young as well as aging MSCs. It is concluded from these findings that rutin and quercetagetin treatment enhance the regeneration efficiency of young and aging MSCs in vivo. These antioxidants can be effectively utilized to improve cellular therapy for myocardial infarction by suppressing ROS production.

Protective effect of hydroxysafflor yellow A on MSCs against senescence induced by d-galactose

ObjectiveTo examine the protective effects of hydroxysafflor yellow A (HSYA) against the senescence of mesenchymal stem cells (MSCs) induced by d-galactose (d-gal) in vitro, and investigate the potential mechanism involved. MethodsGrouping experiment, Normal control (NC) group: conventional culture with complete medium; Senescence group: MSCs were cultured for 48 h with complete medium containing 10 g/L d-gal; HSYA group: on the basis of senescence induction, HSYA with the suitable concentration was used to protect MSCs. The key experimental indices associated with oxidative stress, inflammatory response, cell senescence, proliferation and apoptosis were measured through chemical colorimetry, β-galactosidase staining, EdU incorporation and flow cytometry, respectively. The relative quantity (RQ) of proteins related closely to cell proliferation, apoptosis, and NF-κB signaling were measured by Western blotting. ResultsAs compared with Senescence group, treatment with HSYA (120 mg/L) effectively ameliorated the adverse situation of MSCs. Oxidation stress and inflammation along with d-Gal induction was dramatically alleviated in MSCs; The β-Gal-positive staining indicated that MSC senescence was significantly mitigated; The proliferative capability of MSCs was significantly increased by up-regulating PCNA and inhibiting p16 expression; The anti-apoptotic effect on MSCs was exerted by down-regulating the RQ of cleaved Caspase-3 and Bax; The activity of NF-κB signaling in MSCs was notably suppressed through inhibiting phosphorylation of IKKβ and p65. ConclusionHSYA (120 mg/L) significantly delayed the d-Gal-induced senescence process in MSCs through attenuating inflammatory reaction and oxidative stress, and suppressing the activity of NF-κB signaling.

Nicotinamide Mononucleotide Supplementation Improves Mitochondrial Dysfunction and Rescues Cellular Senescence by NAD+/Sirt3 Pathway in Mesenchymal Stem Cells.

In vitro expansion-mediated replicative senescence has severely limited the clinical applications of mesenchymal stem cells (MSCs). Accumulating studies manifested that nicotinamide adenine dinucleotide (NAD+) depletion is closely related to stem cell senescence and mitochondrial metabolism disorder. Promoting NAD+ level is considered as an effective way to delay aging. Previously, we have confirmed that nicotinamide mononucleotide (NMN), a precursor of NAD+, can alleviate NAD+ deficiency-induced MSC senescence. However, whether NMN can attenuate MSC senescence and its underlying mechanisms are still incompletely clear. The present study herein showed that late passage (LP) MSCs displayed lower NAD+ content, reduced Sirt3 expression and mitochondrial dysfunction. NMN supplementation leads to significant increase in intracellular NAD+ level, NAD+/ NADH ratio, Sirt3 expression, as well as ameliorated mitochondrial function and rescued senescent MSCs. Additionally, Sirt3 over-expression relieved mitochondrial dysfunction, and retrieved senescence-associated phenotypic features in LP MSCs. Conversely, inhibition of Sirt3 activity via a selective Sirt3 inhibitor 3-TYP in early passage (EP) MSCs resulted in aggravated cellular senescence and abnormal mitochondrial function. Furthermore, NMN administration also improves 3-TYP-induced disordered mitochondrial function and cellular senescence in EP MSCs. Collectively, NMN replenishment alleviates mitochondrial dysfunction and rescues MSC senescence through mediating NAD+/Sirt3 pathway, possibly providing a novel mechanism for MSC senescence and a promising strategy for anti-aging pharmaceuticals.

Aging and Mesenchymal Stem Cells: Basic Concepts, Challenges and Strategies.

Aging and frailty are complex processes implicating multifactorial mechanisms, such as replicative senescence, oxidative stress, mitochondrial dysfunction, or autophagy disorder. All of these mechanisms drive dramatic changes in the tissue environment, such as senescence-associated secretory phenotype factors and inflamm-aging. Thus, there is a demand for new therapeutic strategies against the devastating effects of the aging and associated diseases. Mesenchymal stem cells (MSC) participate in a "galaxy" of tissue signals (proliferative, anti-inflammatory, and antioxidative stress, and proangiogenic, antitumor, antifibrotic, and antimicrobial effects) contributing to tissue homeostasis. However, MSC are also not immune to aging. Three strategies based on MSC have been proposed: remove, rejuvenate, or replace the senescent MSC. These strategies include the use of senolytic drugs, antioxidant agents and genetic engineering, or transplantation of younger MSC. Nevertheless, these strategies may have the drawback of the adverse effects of prolonged use of the different drugs used or, where appropriate, those of cell therapy. In this review, we propose the new strategy of "Exogenous Restitution of Intercellular Signalling of Stem Cells" (ERISSC). This concept is based on the potential use of secretome from MSC, which are composed of molecules such as growth factors, cytokines, and extracellular vesicles and have the same biological effects as their parent cells. To face this cell-free regenerative therapy challenge, we have to clarify key strategy aspects, such as establishing tools that allow us a more precise diagnosis of aging frailty in order to identify the therapeutic requirements adapted to each case, identify the ideal type of MSC in the context of the functional heterogeneity of these cellular populations, to optimize the mass production and standardization of the primary materials (cells) and their secretome-derived products, to establish the appropriate methods to validate the anti-aging effects and to determine the most appropriate route of administration for each case.

Multi-Omics Analysis of Human Mesenchymal Stem Cell Guides Perinatal MSC Based Cellular Therapy for Splenectomy-Nonresponsive Refractory Immune Thrombocytopenia: A Phase I Clinical Trial

Mesenchymal stem cells (MSCs) are a heterogeneous population with the capacities of self-renewal, tissue regeneration and immunoregulation, which have attracted intensive attention for their potential application in the treatment of various immune disorders. However, the immunosuppressive efficacy of these therapies based on MSC products has not been thoroughly characterized, which may lead to inconsistent outcomes of MSC therapy in clinical trials. Cellular senescence is a state that imposes permanent proliferative arrest on cells in response to various types of stress and damage. Evidence suggests that aging MSCs tend to have a compromised immunosuppressive capability for inhibiting T cells. However, the underlying cellular and molecular mechanisms are poorly understood. It is also unknown whether the proportions and states of senescent cells in MSC products derived from various donors and different culture passages is associated with dissonant outcomes across clinical trials of MSC therapies. Immune thrombocytopenia (ITP) is an autoimmune disease characterized by immune-mediated destruction of circulating platelets (PLTs) and suppression of PLT production. It has been reported that autoantibody-coated PLTs undergo accelerated clearance through the spleen macrophage. However, anti-PLT antibodies are detected in less than 50% of patients, which raises the possibility of alternative mechanisms of PLT destruction. In line with this, splenectomy, which removes the primary site of PLT destruction and inhibits B-cell-mediated autoantibody production, has been shown to be the most effective therapy for steroid-refractory or steroid-dependent ITP and offers the highest rate of durable response (60% to 70%) compared with other therapies. Nevertheless, 30% to 40% of refractory ITP patients still show no response to splenectomy, indicating a B-cell-independent pathogenic mechanism. Abnormal function of T cells has been reported in ITP patients, which could collectively drive the autoimmune process. Therefore, the immune mechanism underpinning ITP should be further investigated. Additionally, it is of great value to explore new therapeutic options, such as MSC-based cellular therapy, especially for splenectomy-nonresponsive refractory ITP. Here, we performed a single-cell transcriptomic analysis of clinically used MSCs derived from adipose tissue (AD), the bone marrow (BM), the placental chorionic membrane (PM) and the umbilical cord (UC). The transcriptomic profiles of a total of 45,955 cells revealed an unprecedented level of heterogeneity in cellular senescence. We found that cultured MSCs underwent progressive cell aging, accompanied by the gradual loss of immunosuppressive function. Moreover, compared to adult MSCs (derived from AD and the BM), perinatal MSCs (derived from the PM and UC) had fewer aging cells and exhibited more potent suppressive activity. Mechanistically, we found that the impaired immunomodulatory function of senescent MSCs was associated with reduced expression of the immunosuppressive surface molecule PD-L1, which was demonstrated to be crucial for mediating the immunosuppressive activity of MSCs. Next, we performed single-cell transcriptome analysis and revealed that T-cell hyperactivation was evident in a cohort of refractory ITP patients who had no long-lasting remission after splenectomy. We therefore conducted the registered clinical trial (NCT04014166) of the use of UC-derived MSCs for refractory ITP. In this single-center, phase I trial, six refractory ITP patients received four rounds of three different doses of UC-derived MSC transfusions (0.5 × 106 MSCs/kg, n = 3; 1.0 × 106 MSCs/kg, n = 2; 2.0 × 106 MSCs/kg, n = 1). Notably, all three participants who received 1.0 × 106 or 2.0 × 106 MSCs/kg responded to the transfusions, with a manageable safety profile, while all three participants who received 0.5 × 106 MSCs/kg had no response to the transfusions. Our findings reveal the pivotal roles of cell aging and PD-L1 expression in determining the immunosuppressive efficacy of MSCs and demonstrate that PD-L1 abundant perinatal MSCs are effective in treating refractory ITP with T cell hyperactivation. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Low Oxygen Tension Inhibits Senescence in Bone Marrow Mesenchymal Stem Cells (BMSCs)

Background: Stem cells have been used in regenerative medicine but are so few in the body that they require cell culture. Stem cell culture was performed under normal oxygen tension and passage was carried out until the number of cells was sufficient for therapy. Stem cell cultures under normal oxygen tension do not match the stem cell microenvironment, which can lead to premature senescence. This study aims to determine the association of low oxygen tension with premature senescence of mesenchymal stem cells (MSCs) through inhibition of p21 expression by HIF-1a. Methode: The research method used rabbit bone marrow in New Zealand as a source of MSCs. The results of isolation of MSCs were divided into two groups for cultured on normal and low oxygen tension until 10 passages. Cells were identified using flowcytometry for cd105 and cd34. At early and late passage, the expression of p21 and HIF-1a was examined using immunofluorescence while senescence was examined using β-galactosidase assay. Results: The results showed that in low oxygen cultures HIF-1a expression increased significantly (p &lt;0.05) while p21 expression decreased significantly (p &lt;0.05) as did the β-galactosidase assay. Conclusions: The conclusion of this research is low oxygen tension culture able to decrease premature senescence culture of invitro stem cells mesenchymal through obstacles p21 by HIF-1a.&#x0D; Keywords: p21 expression, HIF-1a expression, late passage, premature senescence.

Anti-aging effect of β-carotene through regulating the KAT7-P15 signaling axis, inflammation and oxidative stress process

BackgroundResearch on aging is growing as the elderly make up a greater share of the population, focusing on reversing and inhibiting the aging process. The exhaustion and senescence of stem cells are the fundamental drivers behind aging. β-Carotene has been depicted to have many biological functions, and we speculate that it may have an anti-aging effect.MethodsFirstly, the anti-aging property of β-carotene was investigated in vitro using mesenchymal stem cells (MSCs) induced by H2O2. The anti-aging effect was characterized using Western-bloting, confocal laser scanning microscopy, indirect immunofluorescence, and immunohistochemistry. The anti-aging property was also tested in vivo using aged mice.ResultsThe in vitro experiment revealed that β-carotene could relieve the aging of MSCs, as evidenced by a series of aging marker molecules such as p16 and p21. β-Carotene appeared to inhibit aging by regulating the KAT7-P15 signaling axis. The in vivo experiment revealed that β-carotene treatment has significantly down-regulated the aging level of tissues and organs.ConclusionsIn this work, we explored the anti-aging effect of β-carotene in vivo and in vitro. The experimental results indicate that β-carotene may be an important potential anti-aging molecule, which can be used as a drug or in functional food to treat aging in the future.

Nanocatalytic Biofunctional MOF Coating on Titanium Implants Promotes Osteoporotic Bone Regeneration through Cooperative Pro-osteoblastogenesis MSC Reprogramming.

An elevated bone microenvironmental reactive oxygen species (ROS) level is a hallmark of osteoporosis that often leads to the dysfunction of bone-related mesenchymal stem cells (MSCs), which would induce MSC senescence and severely undermine their osteoblastic potential. Herein, we report the in situ construction of bone microenvironment-responsive biofunctional metal-organic framework (bio-MOF) coating on the titanium surface through the coordination between p-xylylenebisphosphonate (PXBP) and Ce/Sr ions by a hydrothermal method. Taking advantage of the anchored Ce and Sr ions, the AHT-Ce/SrMOF implants demonstrate on-demand superoxide dismutase and catalase-like catalytic activities to decompose ROS in MSCs and restore their mitochondrial functions. In vitro analysis showed that the AHT-Ce/SrMOF implants substantially activated the AMP-activated protein kinase (AMPK) signaling pathway in MSCs and reduced the ROS levels. Meanwhile, MSCs grown on AHT-Ce/SrMOF implants displayed significantly higher expressions of the mitochondrial fission marker (DRP1), mitochondrial fusion marker (MFN2 and OPA1), and mitophagy marker (PINK1 and LC3) than those of the AHT-CeMOF and AHT-SrMOF groups, which indicated that the bio-MOF could amend mitochondrial function in MSCs to reverse senescence. In vivo evaluations showed that the bio-MOF-coated Ti implants could restore MSC function in the implant site and promote new bone formation, leading to improved osteointegration in osteoporotic rat. This study may improve implant-mediated fracture healing in the clinics.

Cyclin-Dependent Kinase 1 Inhibition Potentiates the Proliferation of Tonsil-Derived Mesenchymal Stem Cells by Delaying Cellular Senescence.

Mesenchymal stem cells (MSCs) have been widely used in tissue regeneration and stem cell therapy and are currently being tested in numerous clinical trials. Senescence-related changes in MSC properties have attracted considerable attention. Senescent MSCs exhibit a compromised potential for proliferation; senescence acts as a stress response that prevents the proliferation of dysfunctional cells by inducing an irreversible cell cycle arrest. Here, we established a senescent MSC model using senescence-associated β-galactosidase, proliferation, and cell cycle assays. We further identified novel biomarker candidates for old, senescent tonsil-derived MSCs (TMSCs) using transcriptomics. A plot of the cellular senescence pathway showed cyclin-dependent kinase 1 (CDK1; +8-fold) and CDK2 (+2-fold), and transforming growth factor beta 2 (TGFB2; +2-fold) showed significantly higher expression in old TMSCs than in young TMSCs. The CDK family was shown to be related to cell cycle and proliferation, as confirmed by quantitative RT-PCR. As replicative senescence of TMSCs, the gene and protein expression of CDK1 was significantly increased, which was further validated by inhibiting CDK1 using an inhibitor and siRNA. Taken together, we suggest that the CDK1 can be used as a selective senescence biomarker of MSCs and broaden the research criteria for senescent mechanisms.

JAK-STAT signaling mediates the senescence of cartilage-derived stem/progenitor cells.

Aging is a major risk factor for degenerative joint diseases, such as osteoarthritis (OA). Previous studies have confirmed the link between senescent mesenchymal stem cells (MSCs) and OA. Cartilage-derived stem/progenitor cells (CSPCs) with MSCs properties have been extracted from a variety of species. We inferred that the senescence of CSPCs may promote the development of osteoarthritis. However, the cellular and molecular mechanisms of CSPCs senescence remains unknown. In this study, we investigated the role of JAK-STAT signaling pathway in a replicative senescence model of CSPCs. We showed that the late CSPCs (> 15th passage) exhibited distinct senescent phenotypes, including increased proportion of β-gal positive senescent cells and F-actin content, as well as cell cycle arrest. In late CSPCs, the activity of JAK-STAT signaling pathway was significantly increased. Activation of JAK-STAT signaling pathway promoted cell senescence in early CSPCs (< 6th passage). Conversely, pharmacological inhibition or genetic knockdown of JAK-STAT signaling pathway attenuated cell senescence in late CSPCs. In conclusion, our results demonstrated the critical role of JAK-STAT signaling pathway in CSPCs senescence.

Proteomics and post-translational modifications analysis of umbilical mesenchymal stem cells aging

Mesenchymal stem cells (MSCs) are considered to be critical for regenerative medicine. However, long-term culturing of MSCs will induce aging of MSCs, and thereafter impair cellular function. Changes in proteomics have been reported to be involved in cell aging, and therefore investigations on cell aging of MSCs at levels of proteomics and post-translational protein modifications (PTM) are ultimately important. In the present study, human umbilical cord mesenchymal stem cells (hUMSCs) were exposed to different culture conditions for either 7 or 30 days. Proteins changes during cell culture were investigated using tandem mass tag (TMT) labeling quantitative approach, and N-glycosylation patterns were analyzed using multistage mass spectrometry. We identified 66 proteins (fold change >1.50) that were differentially expressed in long-term culture. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that aging exerts a side effect on hUMSCs by affecting various molecular functions and biological processes, such as lysosome, autophagy and post-translational protein modification. Glycosylation analysis indicates that cell N-glycan patterns are associated with aging of MSCs. Our results presented here should contribute to future studies on cell aging and cellular quality controls related to MSCs as regenerative medicine.

N-methyl-D-aspartate receptor blockers attenuate bleomycin-induced pulmonary fibrosis by inhibiting endogenous mesenchymal stem cells senescence

BackgroundA large number of our previous studies showed that endogenous glutamate and N-methyl-D-aspartate receptor (NMDAR) activation may be involved in various types of acute lung injury, airway inflammation, asthma, and pulmonary fibrosis. In animal models, the transplantation of exogenous bone marrow mesenchymal stem cells (BM-MSCs) is the most promising treatment for idiopathic pulmonary fibrosis. However, there are limited reports on the status of endogenous BM-MSCs in the process of bleomycin-induced pulmonary fibrosis in animals.MethodsWe constructed a mouse model of bleomycin-induced pulmonary fibrosis. In vitro, the senescence model of BM-MSCs was constructed with hydrogen peroxide and high concentration of N-methyl-D-aspartate (NDMA). The changes in aging-related indexes were detected by senescence associated beta-galactosidase (SA-β-gal) staining, western blot, flow cytometry and real time-PCR. The epithelial-mesenchymal transformation (EMT) changes of mouse lung epithelial cells (MLE-12) co-cultured with senescent BM-MSCs were detected by immunofluorescence and western blotting.ResultsWe observed that endogenous BM-MSCs senescence occurs during bleomycin-induced pulmonary fibrosis in mice, and the model group had a higher expression level of the NMDAR subunit than the control group. We observed a significant increase in NMDAR subunit expression in a hydrogen peroxide-induced senescent cell model in vitro. BM-MSCs showed senescence-related phenotype and cell cycle arrest after high concentration of NMDA treatment. At the same time, the expression levels of the classic Wingless and int-1 (Wnt) pathway protein β-cantenin and downstream cyclin D1 also changed. In the co-culture of aged BM-MSCs and MLE-12 cells, EMT can be promoted in MLE-12 cells, and MK-801 can partially antagonize the occurrence of EMT. The NMDAR antagonist can partially prevent the above phenomenon.ConclusionsHigh concentrations of NMDA can promote senescence of BM-MSCs. NMDAR blockers may inhibit endogenous BM-MSCs aging through the WNT signaling pathway, thereby reducing the effect of bleomycin-induced pulmonary fibrosis.

Phytochemicals as new therapeutic candidates simultaneously stimulate proliferation and counteract senescence of stem cells

Mesenchymal stem cells (MSCs) are promising candidates for regenerative therapy. However, the research and clinical application of MSCs are greatly hindered by the limited cells proliferation and replicative senescence. Therapeutic agents that can both enhance the proliferative ability and decrease the replicative senescence of MSCs are greatly needed, however, not been reported yet. Herein, for the first time, we identified 11 natural compounds from medicinal plants with both excellent proliferative and anti-senescence abilities in MSCs. The qPCR analysis indicated underlying mechanisms associated with fibroblast growth factor, transforming growth factor, Wnt/β-catenin and leukemia-induced factor in proliferation; the reactive oxygen species production, mitochondrial dysfunction autophagy and proteostasis are involved in cells senescence-related mechanism. Phytochemicals are demonstrated as novel therapeutic candidates with promising effects in both stimulating proliferation and retarding replicative senescence of stem cells with high safety.

Insulin-like growth factor binding proteins 7 prevents dental pulp-derived mesenchymal stem cell senescence via metabolic downregulation of p21.

Cellular senescence affects the efficacy of mesenchymal stem cells (MSCs)-mediated tissue regeneration. Insulin-like growth factor binding proteins-7 (IGFBP7), as a member of the IGF family, is associated with osteogenic differentiation and the senescence of MSCs, but its exact function and mechanism remain unclear. We found IGFBP7 promoted the osteogenic differentiation and prevented the senescence of dental pulp-derived MSCs (DPSCs), as observed in the gain-of-function and loss-of-function analyses, the senescence-associated marker p21 showed the most pronounced expression changes. We demonstrated that IGFBP7 activated the biological activity of SIRT1 deacetylase via metabolism, resulting in a deacetylation of H3K36ac and a decrease of the binding affinity of H3K36ac to p21 promoter, thereby reducing the transcription of p21, which ultimately prevents DPSCs senescence and promotes tissue regeneration. The activation of the mitochondrial electron transport chain (ETC) by Coenzyme Q10 could rescue the promotion of DPSC senescence induced by the knockdown of IGFBP7, whereas the inhibition of ETC by rotenone attenuated the prevention of DPSC senescence induced by IGFBP7 overexpression. In conclusion, our present results reveal a novel function of IGFBP7 in preventing DPSC senescence via the metabolism-induced deacetylation of H3K36ac and reduction of p21 transcription, suggesting that IGFBP7 is a potential target for promoting tissue regeneration in an aging environment.