Human Mesenchymal Stem Cell Aging Research Articles

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.

GATA4-dependent regulation of the secretory phenotype via MCP-1underlies lamin A-mediated human mesenchymal stem cell aging

Defects in the nuclear lamina occur during physiological aging and as aresult of premature aging disorders. Aging is also accompanied by an increase intranscription of genes encoding cytokines and chemokines, a phenomenon known as thesenescence-associated secretory phenotype (SASP). Progerin and prelamin A triggerpremature senescence and loss of function of human mesenchymal stem cells (hMSCs),but little is known about how defects in nuclear lamin A regulate SASP. Here, weshow that both progerin overexpression and ZMPSTE24 depletion induce paracrinesenescence, especially through the expression of monocyte chemoattractant protein-1(MCP-1), in hMSCs. Importantly, we identified that GATA4 is a mediator regulatingMCP-1 expression in response to prelamin A or progerin in hMSCs.Co-immunoprecipitation revealed that GATA4 expression is maintained due to impairedp62-mediated degradation in progerin-expressing hMSCs. Furthermore, depletion ofGATA4 abrogated SASP-dependent senescence through suppression of NF-ĸB and MCP-1 inhMSCs with progerin or prelamin A. Thus, our findings indicate that abnormal lamin Aproteins trigger paracrine senescence through a GATA4-dependent pathway in hMSCs.This molecular link between defective lamin A and GATA4 can provide insights intophysiological aging and pathological aging disorders.

Prelamin A and Oct-1: a puzzle of aging

Aging is a tremendously complex biological process, in which several dys-regulated cellular pathways converge, such as alterations in the nuclear lamina which contribute to genomic instability, one of the hallmarks of aging [1]. The nuclear lamina is mainly composed of A and B-type lamins, type V intermediate filaments which establish a network that functions as a structural scaffold for the cell nucleus. Lamins interact also with chromatin and transcription factors functioning in DNA synthesis and gene transcription, therefore controlling indispensable cellular processes such as cell proliferation and differentiation. Prelamin A is the first unprocessed product of the LMNA gene which undergoes several posttranslational modifications before becoming mature lamin A, an essential component of nuclear lamina. Mutations in the LMNA gene or in genes that participate in lamin A maturation lead to the accumulation of lamin A precursors causing deep alterations in nuclear architecture, a hallmark of premature aging diseases such as Hutchinson-Gilford progeria syndrome or mandibuloacral dysplasia (reviewed in [2]). The finding that low levels of prelamin A are also present in cells of elderly individuals suggests that it exerts a role in physiological aging [3], reinforcing the relevance of premature aging cell models to study the molecular mechanisms underlying human aging. It is worth noting that the mainly affected tissues (adipose tissue, bone, muscle) in LMNA-linked premature aging syndromes are from mesenchymal origin. In line with this finding, there is a decrease in the regenerative potential of adult stem cells in aging (reviewed in [1]). These observations suggest that the accumulation of prelamin A could be especially deleterious in human mesenchymal stem cells (hMSCs) in aging (physiological or premature). In fact, we demonstrated this hypothesis in a human experimental model based on prelamin A-accumulating hMSCs, which showed serious impediments to carry out a proper adipogenic differentiation [4]. In our latest work published in Aging, we focused on understanding the mechanisms underlying aging in a scenario of prelamin A accumulation, taking advantage of the experimental model mentioned above [5]. We initially confirmed that prelamin A-accumulating hMSCs exhibited telomere shortening and increased DNA damage response, both hallmarks of aging. Then, we found that prelamin A accumulation resulted in making hMSCs more sensitive to stress conditions, another characteristic of aged cells. Thus, increased ROS levels, impaired autophagy and alteration in the expression of genes related to aging, autophagy and oxidative stress only appeared in hMSCs exposed to a combination of prelamin A accumulation and stress conditions. Regarding autophagy, a cellular process which decays with age (reviewed in [1]), we found that autophagic flux was slowed down only under prelamin A accumulation and stress conditions, in spite of the inhibition of the mTORC1 pathway, a known repressor of autophagy. Importantly, the development of these aging characteristics resulted in a diminished functionality of prelamin A-accumulating hMSCs in vivo. One possible pathogenic mechanism underlying prelamin A accumulation is that relevant levels of prelamin A could alter the network of the nuclear lamina, thus generating a trap for transcription factors. Confirming this hypothesis, we previously reported in our experimental model that prelamin A accumulation pathologically sequestered Sp1 transcription factor at the nuclear envelope of differentiated hMSCs [4]. We wondered then if the altered gene expression profile detected under prelamin A accumulation and stress could be attributed to the defective action of transcription factors. Bioinformatic analysis suggested that Oct-1, a transcription factor known to be associated with lamin B driving the oxidative stress response [6], could be governing this dys-regulated genetic program. We validated this in-silico result finding that accumulated prelamin A and stress conditions acted synergistically to enhance nuclear expression of Oct-1 and prelamin A itself. Furthermore, we found that Oct-1 activity under both these situations was inhibited in hMSCs. These results suggest that although overexpressed under stress signals, Oct-1 is not totally functional in hMSCs due to prelamin A accumulation. Moreover, we found that Oct-1 silencing resulted in an increase in senescence and autophagic flux in hMSCs. Our findings reveal the relevance of this human experimental model to delve into the molecular mechanisms of human mesenchymal stem cell aging. Thus, we have found that the activity of Oct-1 can be attenuated by prelamin A accumulation in stressed hMSCs, and that this effect is, at least in part, responsible for the enhanced aging phenotype of these cells. Strengthening this observation, a later work published in Aging by the Latanzzi group showed that prelamin A sequestered Oct-1 at nuclear envelope in fibroblasts from premature aging patients [7]. These results clearly indicate that Oct-1 and prelamin A are two linked pieces in the complex puzzle of aging. Nevertheless, there are many questions deserving further studies, such as the intriguing observation that stress conditions seem to be a boost for the appearance/enhancement of some aging phenotypes in hMSCs that already accumulate prelamin A.

MiR-543 and miR-590-3p regulate human mesenchymal stem cell aging via direct targeting of AIMP3/p18.

Previously, AIMP3 (aminoacyl-tRNAsynthetase-interacting multifunctional protein-3) was shown to be involved in the macromolecular tRNA synthetase complex or to act as a tumor suppressor. In this study, we report a novel role of AIMP3/p18 in the cellular aging of human mesenchymal stem cells (hMSCs). We found that AIMP3/p18 expression significantly increased in senescent hMSCs and in aged mouse bone marrow-derived MSCs (mBM-MSCs). AIMP3/p18 overexpression is sufficient to induce the cellular senescence phenotypes with compromised clonogenicity and adipogenic differentiation potential. To identify the upstream regulators of AIMP3/p18 during senescence, we screened for potential epigenetic regulators and for miRNAs. We found that the levels of miR-543 and miR-590-3p significantly decreased under senescence-inducing conditions, whereas the AIMP3/p18 protein levels increased. We demonstrate for the first time that miR-543 and miR-590-3p are able to decrease AIMP3/p18 expression levels through direct binding to the AIMP/p18 transcripts, which further compromised the induction of the senescence phenotype. Taken together, our data demonstrate that AIMP3/p18 regulates cellular aging in hMSCs possibly through miR-543 and miR-590-3p.

Correction: A p38 MAPK-Mediated Alteration of COX-2/PGE2 Regulates Immunomodulatory Properties in Human Mesenchymal Stem Cell Aging

Correction: A p38 MAPK-Mediated Alteration of COX-2/PGE2 Regulates Immunomodulatory Properties in Human Mesenchymal Stem Cell Aging

A p38 MAPK-mediated alteration of COX-2/PGE2 regulates immunomodulatory properties in human mesenchymal stem cell aging.

Because human mesenchymal stem cells (hMSC) have profound immunomodulatory effects, many attempts have been made to use hMSCs in preclinical and clinical trials. For hMSCs to be used in therapy, a large population of hMSCs must be generated by in vitro expansion. However, the immunomodulatory changes following the in vitro expansion of hMSCs have not been elucidated. In this study, we evaluated the effect of replicative senescence on the immunomodulatory ability of hMSCs in vitro and in vivo. Late-passage hMSCs showed impaired suppressive effect on mitogen-induced mononuclear cell proliferation. Strikingly, late-passage hMSCs had a significantly compromised protective effect against mouse experimental colitis, which was confirmed by gross and histologic examination. Among the anti-inflammatory cytokines, the production of prostaglandin E2 (PGE2) and the expression of its primary enzyme, cyclooxygenase-2 (COX-2), were profoundly increased by pre-stimulation with interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α), and this response was significantly decreased with consecutive passages. We demonstrated that the impaired phosphorylation activity of p38 MAP kinase (p38 MAPK) in late-passage hMSCs led to a compromised immunomodulatory ability through the regulation of COX-2. In conclusion, our data indicate that the immunomodulatory ability of hMSCs gradually declines with consecutive passages via a p38-mediated alteration of COX-2 and PGE2 levels.

MicroRNA-141-3p plays a role in human mesenchymal stem cell aging by directly targeting ZMPSTE24

MicroRNA-141-3p plays a role in human mesenchymal stem cell aging by directly targeting ZMPSTE24

MicroRNA-141-3p plays a role in human mesenchymal stem cell aging by directly targeting ZMPSTE24

Human mesenchymal stem cell (hMSC) aging may lead to a reduced tissue regeneration capacity and a decline in physiological functions. However, the molecular mechanisms controlling hMSC aging in the context of prelamin A accumulation are not completely understood. In this study, we demonstrate that the accumulation of prelamin A in the nuclear envelope results in cellular senescence and potential downstream regulatory mechanisms responsible for prelamin A accumulation in hMSCs. We show for the first time that ZMPSTE24, which is involved in the post-translational maturation of lamin A, is largely responsible for the prelamin A accumulation related to cellular senescence in hMSCs. Direct binding of miR-141-3p to the 3'UTR of ZMPSTE24 transcripts was confirmed using a 3'UTR-luciferase reporter assay. We also found that miR-141-3p, which is overexpressed during senescence as a result of epigenetic regulation, is able to decrease ZMPSTE24 expression levels, and leads to an upregulation of prelamin A in hMSCs. This study provides new insights into mechanisms regulating MSC aging and may have implications for therapeutic application to reduce age-associated MSC pool exhaustion.