Senescence-Associated Secretory Phenotype Suppression Mediated by Small-Sized Mesenchymal Stem Cells Delays Cellular Senescence through TLR2 and TLR5 Signaling

Melatonin attenuates dental pulp stem cells senescence due to vitro expansion via inhibiting MMP3

OBJECTIVE

We aimed to identify the crucial genes involved in dental pulp stem cell (DPSC) senescence and evaluate the impact of melatonin on DPSC senescence.

METHODS

Western blotting, SA-β-Gal staining and ALP staining were used to evaluate the senescence and differentiation potential of DPSCs. The optimal concentration of melatonin was determined using the CCK-8 assay. Differentially expressed genes (DEGs) involved in DPSC senescence were obtained via bioinformatics analysis, followed by RT-qPCR. Gain- and loss-of-function studies were conducted to explore the role of MMP3 in DPSC in vitro expansion and in response to melatonin. GSEA was employed to analyse MMP3-related pathways in cellular senescence.

RESULTS

Treatment with 0.1 μM melatonin attenuated cellular senescence and differentiation potential suppression in DPSCs due to long-term in vitro expansion. MMP3 was a crucial gene in senescence, as confirmed by bioinformatics analysis, RT-qPCR and Western blotting. Furthermore, gain- and loss-of-function studies revealed that MMP3 played a regulatory role in cellular senescence. Rescue assays showed that overexpression of MMP3 reversed the effect of melatonin on senescence. GSEA revealed that the MMP3-dependent anti-senescence effect of melatonin was associated with the IL6-JAK-STAT3, TNF-α-Signalling-VIA-NF-κB, COMPLEMENT, NOTCH Signalling and PI3K-AKT-mTOR pathways.

CONCLUSION

Melatonin attenuated DPSC senescence caused by long-term expansion by inhibiting MMP3.

Size-Based Microfluidic-Enriched Mesenchymal Stem Cell Subpopulations Enhance Articular Cartilage Repair

BACKGROUND

The functional heterogeneity of culture-expanded mesenchymal stem cells (MSCs) has hindered the clinical application of MSCs. Previous studies have shown that MSC subpopulations with superior chondrogenic capacity can be isolated using a spiral microfluidic device based on the principle of inertial cell focusing.

HYPOTHESIS

The delivery of microfluidic-enriched chondrogenic MSCs that are consistent in size and function will overcome the challenge of the functional heterogeneity of expanded MSCs and will significantly improve MSC-based cartilage repair.

STUDY DESIGN

Controlled laboratory study.

METHODS

A next-generation, fully automated multidimensional double spiral microfluidic device was designed to provide more refined and efficient isolation of MSC subpopulations based on size. Analysis of in vitro chondrogenic potential and RNA sequencing was performed on size-sorted MSC subpopulations. In vivo cartilage repair efficacy was demonstrated in an osteochondral injury model in 12-week-old rats. Defects were implanted with MSC subpopulations (n = 6 per group) and compared with those implanted with unsegregated MSCs (n = 6). Osteochondral repair was assessed at 6 and 12 weeks after surgery by histological, micro-computed tomography, and mechanical analysis.

RESULTS

A chondrogenic MSC subpopulation was efficiently isolated using the multidimensional double spiral device. RNA sequencing revealed distinct transcriptomic profiles and identified differential gene expression between subpopulations. The delivery of a chondrogenic MSC subpopulation resulted in improved cartilage repair, as indicated by histological scoring, the compression modulus, and micro-computed tomography of the subchondral bone.

CONCLUSION

We have established a rapid, label-free, and reliable microfluidic protocol for more efficient size-based enrichment of a chondrogenic MSC subpopulation. Our proof-of-concept in vivo study demonstrates the enhanced cartilage repair efficacy of these enriched chondrogenic MSCs.

CLINICAL RELEVANCE

The delivery of microfluidic-enriched chondrogenic MSCs that are consistent in size and function can overcome the challenge of the functional heterogeneity of expanded MSCs, resulting in significant improvement in MSC-based cartilage repair. The availability of such rapid, label-free enriched chondrogenic MSCs can enable better cell therapy products for cartilage repair with improved treatment outcomes.

Identification and validation of senescence-related genes in polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is an exceedingly intractable issue affecting female endocrine and reproductive health. However, the etiology and intricate pathological mechanisms of PCOS remain unclear. Nowadays, aging was found to share multiple common pathological mechanisms with PCOS, which causes probing into the pathogenesis of PCOS from senescence. However, no bioinformatics analyses have specifically focused on connection between PCOS and ovarian aging.

METHODS

Differentially expressed aging-related genes in PCOS were identified and then analyzed using function enrichment method. Hub genes were determined based on multiple algorithms, and expression validation of hub genes was performed in both datasets and experiments (human granulosa-like tumor cell line, KGN; human Granulosa Cell, hGCs). Finally, a transcription factor-miRNA-gene network of hub genes was constructed.

RESULTS

Here, we identified 73 aging-related differential expression genes (ARDEGs) by intersecting DEGs in PCOS and senescence-related gene set. Furthermore, we performed biological functions and potential pathways of ARDEGs and potential hub genes were also screened by multiple algorithms. From the perspective of immune dysfunction, we analyzed the correlation between PCOS and immune cells. Finally, TF-miRNA-gene networks were constructed. Finally, TF-miRNA-gene networks were constructed.

CONCLUSIONS

Our work aimed to elucidate the relation between PCOS and cellular senescence based on bioinformatics strategy, deepening the understanding of mechanisms and to seek for novel therapy strategies for improving reproductive lifespan and female health. Exploring the potential molecular mechanism of cell aging in PCOS is expected to bring a new breakthrough for PCOS diagnosis and therapy strategies. And this, might deepen our understanding about intricate mechanisms of ovarian aging.

Identification of hub genes and pathways associated with cellular senescence in diabetic foot ulcers via comprehensive transcriptome analysis

This research aimed to find important genes and pathways related to cellular senescence (CS) in diabetic foot ulcers (DFU) and to estimate the possible pathways through which CS affects diabetic foot healing. The GSE80178 dataset was acquired from the Gene Expression Omnibus (GEO) database, containing six DFU and three diabetic foot skin (DFS) samples. The limma package was used to identify differentially expressed genes (DEGs). At the same time, DEGs associated with CS (CS-DEGs) were found using the CellAge database. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted on the CS-DEGs. A protein-protein interaction (PPI) network was built using the String database, and the cytoHubba plug-in within Cytoscape helped identify hub genes. Lastly, the miRNA-TF-mRNA regulatory network for these hub genes was established. In total, 66 CS-DEGs were obtained. These genes mainly focus on CS, Kaposi sarcoma-associated herpesvirus infection and Toll-like receptor signalling pathway. Eight hub genes were identified to regulate cell senescence in DFU, including TP53, SRC, SIRT1, CCND1, EZH2, CXCL8, AR and CDK4. According to miRNA-TF-mRNA regulatory network, hsa-mir-132-3p/SIRT1/EZH2 axis is involved in senescence cell accumulation in DFU.

Relationship among α‑synuclein, aging and inflammation in Parkinson's disease (Review)

Parkinson's disease (PD) is a common neurodegenerative pathology whose major clinical symptoms are movement disorders. The main pathological characteristics of PD are the selective death of dopaminergic (DA) neurons in the pars compacta of the substantia nigra and the presence of Lewy bodies containing α-synuclein (α-Syn) within these neurons. PD is associated with numerous risk factors, including environmental factors, genetic mutations and aging. In many cases, the complex interplay of numerous risk factors leads to the onset of PD. The mutated α-Syn gene, which expresses pathologicalα-Syn protein, can cause PD. Another important feature of PD is neuroinflammation, which is conducive to neuronal death. α-Syn is able to interact with certain cell types in the brain, including through phagocytosis and degradation of α-Syn by glial cells, activation of inflammatory pathways by α-Syn in glial cells, transmission of α-Syn between glial cells and neurons, and interactions between peripheral immune cells and α-Syn. In addition to the aforementioned risk factors, PD may also be associated with aging, as the prevalence of PD increases with advancing age. The aging process impairs the cellular clearance mechanism, which leads to chronic inflammation and the accumulation of intracellular α-Syn, which results in DA neuronal death. In the present review, the age-associated α-Syn pathogenicity and the interactions between α-Syn and certain types of cells within the brain are discussed to facilitate understanding of the mechanisms of PD pathogenesis, which may potentially provide insight for the future clinical treatment of PD.

Meta-analysis of senescent cell secretomes to identify common and specific features of the different senescent phenotypes: a tool for developing new senotherapeutics

DNA damage resulting from genotoxic injury can initiate cellular senescence, a state characterized by alterations in cellular metabolism, lysosomal activity, and the secretion of factors collectively known as the senescence-associated secretory phenotype (SASP). Senescence can have beneficial effects on our bodies, such as anti-cancer properties, wound healing, and tissue development, which are attributed to the SASP produced by senescent cells in their intermediate stages. However, senescence can also promote cancer and aging, primarily due to the pro-inflammatory activity of SASP.Studying senescence is complex due to various factors involved. Genotoxic stimuli cause random damage to cellular macromolecules, leading to variations in the senescent phenotype from cell to cell, despite a shared program. Furthermore, senescence is a dynamic process that cannot be analyzed as a static endpoint, adding further complexity.Investigating SASP is particularly intriguing as it reveals how a senescence process triggered in a few cells can spread to many others, resulting in either positive or negative consequences for health. In our study, we conducted a meta-analysis of the protein content of SASP obtained from different research groups, including our own. We categorized the collected omic data based on: i) cell type, ii) harmful agent, and iii) senescence stage (early and late senescence).By employing Gene Ontology and Network analysis on the omic data, we identified common and specific features of different senescent phenotypes. This research has the potential to pave the way for the development of new senotherapeutic drugs aimed at combating the negative consequences associated with the senescence process. Video Abstract.

Senescence induces fundamental changes in the secretome of mesenchymal stromal cells (MSCs): implications for the therapeutic use of MSCs and their derivates

Mesenchymal stromal cells (MSCs) are a heterogeneous population containing multipotent adult stem cells with a multi-lineage differentiation capacity, which differentiated into mesodermal derivatives. MSCs are employed for therapeutic purposes and several investigations have demonstrated that the positive effects of MSC transplants are due to the capacity of MSCs to modulate tissue homeostasis and repair via the activity of their secretome. Indeed, the MSC-derived secretomes are now an alternative strategy to cell transplantation due to their anti-inflammatory, anti-apoptotic, and regenerative effects. The cellular senescence is a dynamic process that leads to permanent cell cycle arrest, loss of healthy cells' physiological functions and acquiring new activities, which are mainly accrued through the release of many factors, indicated as senescence-associated secretory phenotype (SASP). The senescence occurring in stem cells, such as those present in MSCs, may have detrimental effects on health since it can undermine tissue homeostasis and repair. The analysis of MSC secretome is important either for the MSC transplants and for the therapeutic use of secretome. Indeed, the secretome of MSCs, which is the main mechanism of their therapeutic activity, loses its beneficial functions and acquire negative pro-inflammatory and pro-aging activities when MSCs become senescent. When MSCs or their derivatives are planned to be used for therapeutic purposes, great attention must be paid to these changes. In this review, we analyzed changes occurring in MSC secretome following the switch from healthy to senescence status.

Paracrine Senescence of Mesenchymal Stromal Cells Involves Inflammatory Cytokines and the NF-κB Pathway

It has been known that senescence-associated secretory phenotype (SASP) triggers senescence of the surrounding normal cells. However, SASP signaling regarding mesenchymal stromal cell aging remains to be fully elucidated. Therefore, the present study aimed to clarify the molecular mechanism of late (passage) MSC-induced paracrine SASP-mediated senescence of early (passage) MSCs during ex vivo expansion. Here, we conducted an extensive characterization of senescence features in bone-marrow (BM)-derived MSCs from healthy human donors. Late MSCs displayed an enlarged senescent-like morphology, induced SASP-related proinflammatory cytokines (IL-1α and IL-8), and reduced clonogenic capacity and osteogenic differentiation when compared to early MSCs. Of note, paracrine effects of SASP-related IL-1α and IL-8 from late MSCs induced cellular senescence of early MSCs via an NF-κB-dependent manner. Moreover, cellular senescence of early MSCs was promoted by the synergistic action of IL-1α and IL-8. However, inhibition of NF-κB by shRNA transfection or using inhibitors in early MSCs blocked early MSCs cellular senescence caused by paracrine SASP of late MSCs. In conclusion, these findings reveal that late MSCs display features of senescence and that, during ex vivo expansion, SASP-related proinflammatory cytokines contribute to activate a cellular senescence program in early MSCs that may ultimately impair their functionality.

Aged Callus Skeletal Stem/Progenitor Cells Contain an Inflammatory Osteogenic Population With Increased IRF and NF-κB Pathways and Reduced Osteogenic Potential

Skeletal stem/progenitor cells (SSPCs) are critical for fracture repair by providing osteo-chondro precursors in the callus, which is impaired in aging. However, the molecular signatures of callus SSPCs during aging are not known. Herein, we performed single-cell RNA sequencing on 11,957 CD45-CD31-Ter119- SSPCs isolated from young and aged mouse calluses. Combining unsupervised clustering, putative makers, and DEGs/pathway analyses, major SSPC clusters were annotated as osteogenic, proliferating, and adipogenic populations. The proliferating cluster had a differentiating potential into osteogenic and adipogenic lineages by trajectory analysis. The osteoblastic/adipogenic/proliferating potential of individual clusters was further evidenced by elevated expression of genes related to osteoblasts, adipocytes, or proliferation. The osteogenic cluster was sub-clustered into house-keeping and inflammatory osteogenic populations that were decreased and increased in aged callus, respectively. The majority of master regulators for the inflammatory osteogenic population belong to IRF and NF-κB families, which was confirmed by immunostaining, RT-qPCR, and Western blot analysis. Furthermore, cells in the inflammatory osteogenic sub-cluster had reduced osteoblast differentiation capacity. In conclusion, we identified 3 major clusters in callus SSPCs, confirming their heterogeneity and, importantly, increased IRF/NF-κB-mediated inflammatory osteogenic population with decreased osteogenic potential in aged cells.

HLA-A2 Promotes the Therapeutic Effect of Umbilical Cord Blood-Derived Mesenchymal Stem Cells in Hyperoxic Lung Injury

Mesenchymal stem cells (MSCs) are one of the most extensively studied stem cell types owing to their capacity for differentiation into multiple lineages as well as their ability to secrete regenerative factors and modulate immune functions. However, issues remain regarding their further application for cell therapy. Here, to demonstrate the superiority of the improvement of MSCs, we divided umbilical cord blood-derived MSCs (UCB-MSCs) from 15 donors into two groups based on efficacy and revealed donor-dependent variations in the anti-inflammatory effect of MSCs on macrophages as well as their immunoregulatory effect on T cells. Through surface marker analyses (242 antibodies), we found that HLA-A2 was positively related to the anti-inflammatory and immunoregulatory function of MSCs. Additionally, HLA-A2 mRNA silencing in MSCs attenuated their therapeutic effects in vitro; namely, the suppression of LPS-stimulated macrophages and phytohemagglutinin-stimulated T cells. Moreover, HLA-A2 silencing in MSCs significantly decreased their therapeutic effects in a rat model of hyperoxic lung damage. The present study provides novel insights into the quality control of donor-derived MSCs for the treatment of inflammatory conditions and diseases.

PTX-3 Secreted by Intra-Articular-Injected SMUP-Cells Reduces Pain in an Osteoarthritis Rat Model

Mesenchymal stem cells (MSCs) are accessible, abundantly available, and capable of regenerating; they have the potential to be developed as therapeutic agents for diseases. However, concerns remain in their further application. In this study, we developed a SMall cell+Ultra Potent+Scale UP cell (SMUP-Cell) platform to improve whole-cell processing, including manufacturing bioreactors and xeno-free solutions for commercialization. To confirm the superiority of SMUP-Cell improvements, we demonstrated that a molecule secreted by SMUP-Cells is capable of polarizing inflammatory macrophages (M1) into their anti-inflammatory phenotype (M2) at the site of injury in a pain-associated osteoarthritis (OA) model. Lipopolysaccharide-stimulated macrophages co-cultured with SMUP-Cells expressed low levels of M1-phenotype markers (CD11b, tumor necrosis factor-α, interleukin-1α, and interleukin-6), but high levels of M2 markers (CD163 and arginase-1). To identify the paracrine action underlying the anti-inflammatory effect of SMUP-Cells, we employed a cytokine array and detected increased levels of pentraxin-related protein-3 (PTX-3). Additionally, PTX-3 mRNA silencing was applied to confirm PTX-3 function. PTX-3 silencing in SMUP-Cells significantly decreased their therapeutic effects against monosodium iodoacetate (MIA)-induced OA. Thus, PTX-3 expression in injected SMUP-Cells, applied as a therapeutic strategy, reduced pain in an OA model.

TNF-α and IFN-γ Participate in Improving the Immunoregulatory Capacity of Mesenchymal Stem/Stromal Cells: Importance of Cell-Cell Contact and Extracellular Vesicles

Mesenchymal stem/stromal cells (MSCs) have an immunoregulatory capacity and have been used in different clinical protocols requiring control of the immune response. However, variable results have been obtained, mainly due to the effect of the microenvironment on the induction, increase, and maintenance of MSC immunoregulatory mechanisms. In addition, the importance of cell–cell contact for MSCs to efficiently modulate the immune response has recently been highlighted. Because these interactions would be difficult to achieve in the physiological context, the release of extracellular vesicles (EVs) and their participation as intermediaries of communication between MSCs and immune cells becomes relevant. Therefore, this article focuses on analyzing immunoregulatory mechanisms mediated by cell contact, highlighting the importance of intercellular adhesion molecule-1 (ICAM-1) and the participation of EVs. Moreover, the effects of tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ), the main cytokines involved in MSC activation, are examined. These cytokines, when used at the appropriate concentrations and times, would promote increases in the expression of immunoregulatory molecules in the cell and allow the acquisition of EVs enriched with these molecules. The establishment of certain in vitro activation guidelines will facilitate the design of conditioning protocols to obtain functional MSCs or EVs in different pathophysiological conditions.