Senescence Of Mesenchymal Stem Cells Research Articles

Multiomics profiling reveals VDR as a central regulator of mesenchymal stem cell senescence with a known association with osteoporosis after high-fat diet exposure.

The consumption of a high-fat diet (HFD) has been linked to osteoporosis and an increased risk of fragility fractures. However, the specific mechanisms of HFD-induced osteoporosis are not fully understood. Our study shows that exposure to an HFD induces premature senescence in bone marrow mesenchymal stem cells (BMSCs), diminishing their proliferation and osteogenic capability, and thereby contributes to osteoporosis. Transcriptomic and chromatin accessibility analyses revealed the decreased chromatin accessibility of vitamin D receptor (VDR)-binding sequences and decreased VDR signaling in BMSCs from HFD-fed mice, suggesting that VDR is a key regulator of BMSC senescence. Notably, the administration of a VDR activator to HFD-fed mice rescued BMSC senescence and significantly improved osteogenesis, bone mass, and other bone parameters. Mechanistically, VDR activation reduced BMSC senescence by decreasing intracellular reactive oxygen species (ROS) levels and preserving mitochondrial function. Our findings not only elucidate the mechanisms by which an HFD induces BMSC senescence and associated osteoporosis but also offer new insights into treating HFD-induced osteoporosis by targeting the VDR-superoxide dismutase 2 (SOD2)-ROS axis.

Senescence-Associated Alterations in Matrisome of Mesenchymal Stem Cells.

The process of aging is intimately linked to alterations at the tissue and cellular levels. Currently, the role of senescent cells in the tissue microenvironment is still being investigated. Despite common characteristics, different cell populations undergo distinctive morphofunctional changes during senescence. Mesenchymal stem cells (MSCs) play a pivotal role in maintaining tissue homeostasis. A multitude of studies have examined alterations in the cytokine profile that determine their regulatory function. The extracellular matrix (ECM) of MSCs is a less studied aspect of their biology. It has been shown to modulate the activity of neighboring cells. Therefore, investigating age-related changes in the MSC matrisome is crucial for understanding the mechanisms of tissue niche ageing. This study conducted a broad proteomic analysis of the matrisome of separated fractions of senescent MSCs, including the ECM, conditioned medium (CM), and cell lysate. This is the first time such an analysis has been conducted. It has been established that there is a shift in production towards regulatory molecules and a significant downregulation of the main structural and adhesion proteins of the ECM, particularly collagens, fibulins, and fibrilins. Additionally, a decrease in the levels of cathepsins, galectins, S100 proteins, and other proteins with cytoprotective, anti-inflammatory, and antifibrotic properties has been observed. However, the level of inflammatory proteins and regulators of profibrotic pathways increases. Additionally, there is an upregulation of proteins that can directly cause prosenescent effects on microenvironmental cells (SERPINE1, THBS1, and GDF15). These changes confirm that senescent MSCs can have a negative impact on other cells in the tissue niche, not only through cytokine signals but also through the remodeled ECM.

A Mesenchymal stem cell Aging Framework, from Mechanisms to Strategies.

Mesenchymal stem cells (MSCs) are extensively researched for therapeutic applications in tissue engineering and show significant potential for clinical use. Intrinsic or extrinsic factors causing senescence may lead to reduced proliferation, aberrant differentiation, weakened immunoregulation, and increased inflammation, ultimately limiting the potential of MSCs. It is crucial to comprehend the molecular pathways and internal processes responsible for the decline in MSC function due to senescence in order to devise innovative approaches for rejuvenating senescent MSCs and enhancing MSC treatment. We investigate the main molecular processes involved in senescence, aiming to provide a thorough understanding of senescence-related issues in MSCs. Additionally, we analyze the most recent advancements in cutting-edge approaches to combat MSC senescence based on current research. We are curious whether the aging process of stem cells results in a permanent "memory" and if cellular reprogramming may potentially revert the aging epigenome to a more youthful state.

Extracellular vesicles deviced from hypoxia-3D-GMSCs rescue the mitochondrial dysfunction of aging-GMSCs

Mesenchymal stem cells (MSCs) are ubiquitous multipotent cells exhibiting significant therapeutic potential for various diseases. It is generally accepted that clinical application requires massive expansion of MSCs, which is often accompanied by the occurrence of replicative senescence. Additionally, senescent MSCs exhibit significantly reduced proliferation, differentiation, and therapeutic potential. The scale-up of MSCs production and cellular senescence are major challenges for translational applications. This study first collected extracellular vesicles (EVs) from gingival MSCs (GMSCs) under hypoxia preconditioning combined with 3D dynamic culture (obtained EVs designed as H-3D-EVs). Subsequently, we further explored the effects and mechanisms of H-3D-EVs on aging-GMSCs. The results showed that H-3D-EVs improved the proliferation ability and cell activity of aging-GMSCs, and ameliorated their senescence. mRNA sequencing reveals transcriptomic changes in aging-GMSCs. It was found that H-3D-EVs up-regulated genes related to mitochondrial dynamics, cell cycle, and DNA repair, while down-regulated aging-related genes. Furthermore, we verified that H-3D-EVs corrected the mitochondrial dysfunction of aging-GMSCs by improving mitochondrial dynamics. In summary, this study provides a promising strategy for improving the culture methods of GMSCs and avoiding its senescence in large-scale production.

Conditioned medium of human mesenchymal stem cells affects stem cell senescence in osteoporosis

Systemic transplantation of mesenchymal stem cells (MSCs) and conditioned medium derived from MSCs have been reported to recover bone loss in animal models of osteoporosis; however, the underlying mechanisms remain unclear. We recently reported that extracellular vesicles released from human mesenchymal stem cells (hMSCs) prevent senescence of stem cells in bisphosphonate-related osteonecrosis of the jaw model. In this study, we aimed to compare the effects of conditioned medium (hMSCs-CM) from early and late passage hMSCs on cellular senescence and to verify the benefits of CM from early passage hMSCs in mitigating the progression of osteoporosis through the prevention of cellular senescence. We investigated the distinct endocrine effects of early (P5) and late (P17) passage hMSCs in vitro, as well as the preventive benefits of early passage hMSCs-CM in osteoporosis model triggered by ovariectomy. Our results indicate that long-term cultured hMSCs contributed to the progression of inflammatory transcriptional programs in P5 hMSCs, ultimately impairing their functionality and enhancing senescence-related characteristics. Conversely, early passage hMSCs reversed these alterations. Moreover, early passage hMSCs-CM infused intravenously in a postmenopausal osteoporosis mouse model suppressed bone degeneration and prevented osteoporosis by reducing ovariectomy-induced senescence in bone marrow MSCs and reducing the expression of senescence-associated secretory phenotype-related cytokines. Our findings highlight the high translational value of early passage hMSCs-CM in antiaging intervention and osteoporosis prevention.

Identification of potential biomarkers for aging diagnosis of mesenchymal stem cells derived from the aged donors

BackgroundThe clinical application of human bone-marrow derived mesenchymal stem cells (MSCs) for the treatment of refractory diseases has achieved remarkable results. However, there is a need for a systematic evaluation of the quality and safety of MSCs sourced from donors. In this study, we sought to assess one potential factor that might impact quality, namely the age of the donor.MethodsWe downloaded two data sets from each of two Gene Expression Omnibus (GEO), GSE39035 and GSE97311 databases, namely samples form young (< 65 years of age) and old (> 65) donor groups. Through, bioinformatics analysis and experimental validation to these retrieved data, we found that MSCs derived from aged donors can lead to differential expression of gene profiles compared with those from young donors, and potentially affect the function of MSCs, and may even induce malignant tumors.ResultsWe identified a total of 337 differentially expressed genes (DEGs), including two upregulated and eight downregulated genes from the databases of both GSE39035 and GSE97311. We further identified 13 hub genes. Six of them, TBX15, IGF1, GATA2, PITX2, SNAI1 and VCAN, were highly expressed in many human malignancies in Human Protein Atlas database. In the MSCs in vitro senescent cell model, qPCR analysis validated that all six hub genes were highly expressed in senescent MSCs. Our findings confirm that aged donors of MSCs have a significant effect on gene expression profiles. The MSCs from old donors have the potential to cause a variety of malignancies. These TBX15, IGF1, GATA2, PITX2, SNAI1, VCAN genes could be used as potential biomarkers to diagnosis aging state of donor MSCs, and evaluate whether MSCs derived from an aged donor could be used for therapy in the clinic. Our findings provide a diagnostic basis for the clinical use of MSCs to treat a variety of diseases.ConclusionsTherefore, our findings not only provide guidance for the safe and standardized use of MSCs in the clinic for the treatment of various diseases, but also provide insights into the use of cell regeneration approaches to reverse aging and support rejuvenation.

MicroRNA-18a prevents senescence of mesenchymal stem cells by targeting CTDSPL.

Stem cell therapy requires massive-scale homogeneous stem cells under strict qualification control. However, Prolonged ex vivo expansion impairs the biological functions and results in senescence of mesenchymal stem cells (MSCs). We investigated the function of CTDSPL in the premature senescence process of MSCs and clarified that miR-18a-5p played a prominent role in preventing senescence of long-term cultured MSCs and promoting the self-renewal ability of MSCs. Over-expression of CTDSPL resulted in an enlarged morphology, up-regulation of p16 and accumulation of SA-β-gal of MSCs. The reduced phosphorylated RB suggested cell cycle arrest of MSCs. All these results implied that CTDSPL induced premature senescence of MSCs. We further demonstrated that miR-18a-5p was a putative regulator of CTDSPL by luciferase reporter assay. Inhibition of miR-18a-5p promoted the expression of CTDSPL and induced premature senescence of MSCs. Continuous overexpression of miR-18a-5p improved self-renewal of MSCs by reducing ROS level, increased expression of Oct4 and Nanog, and promoted growth rate and differentiation capability. We reported for the first time that the dynamic interaction of miR-18a-5p and CTDSPL is crucial for stem cell senescence.

Mechanism of Bazi Bushen capsule in delaying the senescence of mesenchymal stem cells based on network pharmacology and experimental validation

Ageing is becoming an increasingly serious problem; therefore, there is an urgent need to find safe and effective anti-ageing drugs. AimsTo investigate the effects of Bazi Bushen capsule (BZBS) on the senescence of mesenchymal stem cells (MSCs) and explore its mechanism of action. MethodsNetwork pharmacology was used to predict the targets of BZBS in delaying senescence in MSCs. For in vitro studies, MSCs were treated with D-gal, BZBS, and NMN, and cell viability, cell senescence, stemness-related genes, and cell cycle were studied using cell counting kit-8 (CCK-8) assay, SA-β-galactosidase (SA-β-gal) staining, Quantitative Real-Time PCR (qPCR) and flow cytometry (FCM), respectively. Alkaline phosphatase (ALP), alizarin red, and oil red staining were used to determine the osteogenic and lipid differentiation abilities of MSCs. Finally, the expression of senescence-related genes and cyclin-related factors was detected by qPCR and western blotting. ResultsNetwork pharmacological analysis suggested that BZBS delayed cell senescence by interfering in the cell cycle. Our in vitro studies suggested that BZBS could significantly increase cell viability (P < 0.01), decrease the quantity of β-galactosidase+ cells (P < 0.01), downregulate p16 and p21 (P < 0.05, P < 0.01), improve adipogenic and osteogenic differentiation, and upregulate Nanog, OCT4 and SOX2 genes (P < 0.05, P < 0.01) in senescent MSCs. Moreover, BZBS significantly reduced the proportion of senescent MSCs in the G0/G1 phase (P < 0.01) and enhanced the expression of CDK4, Cyclin D1, and E2F1 (P < 0.05, P < 0.01, respectively). Upon treatment with HY-50767A, a CDK4 inhibitor, the upregulation of E2F1 was no longer observed in the BZBS group. ConclusionsBZBS can protect MSCs against D-gal-induced senescence, which may be associated with cell cycle regulation via the Cyclin D1/CDK4/E2F1 signalling pathway.

S-Adenosyl-l-Methionine Alleviates the Senescence of MSCs Through the PI3K/AKT/FOXO3a Signaling Pathway.

Cellular senescence significantly affects the proliferative and differentiation capacities of mesenchymal stem cells (MSCs). Identifying key regulators of senescence and exploring potential intervention strategies, including drug-based approaches, are active areas of research. In this context, S-adenosyl-l-methionine (SAM), a critical intermediate in sulfur amino acid metabolism, emerges as a promising candidate for mitigating MSC senescence. In a hydrogen peroxide-induced MSC aging model (100 μM for 2 hours), SAM (50 and 100 μM) was revealed to alleviate the senescence of MSCs, and also attenuated the level of reactive oxygen species and enhanced the adipogenic and osteogenic differentiation in senescent MSCs. In a premature aging mouse model (subcutaneously injected with 150 mg/kg/day d-galactose in the neck and back for 7 weeks), SAM (30 mg/kg/day by gavage for 5 weeks) was shown to delay the overall aging process while increasing the number and thickness of bone trabeculae in the distal femur. Mechanistically, activation of PI3K/AKT signaling and increased phosphorylation of forkhead box O3 (FOXO3a) was proved to be associated with the antisenescence role of SAM. These findings highlight that the PI3K/AKT/FOXO3a axis in MSCs could play a crucial role in MSCs senescence and suggest that SAM may be a potential therapeutic drug for MSCs senescence and related diseases.

Different Levels of Autophagy Activity in Mesenchymal Stem Cells Are Involved in the Progression of Idiopathic Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is an age-related lung interstitial disease that occurs predominantly in people over 65 years of age and for which there is a lack of effective therapeutic agents. It has demonstrated that mesenchymal stem cells (MSCs) including alveolar epithelial cells (AECs) can perform repair functions. However, MSCs lose their repair functions due to their distinctive aging characteristics, eventually leading to the progression of IPF. Recent breakthroughs have revealed that the degree of autophagic activity influences the renewal and aging of MSCs and determines the prognosis of IPF. Autophagy is a lysosome-dependent pathway that mediates the degradation and recycling of intracellular material and is an efficient way to renew the nonnuclear (cytoplasmic) part of eukaryotic cells, which is essential for maintaining cellular homeostasis and is a potential target for regulating MSCs function. Therefore, this review focuses on the changes in autophagic activity of MSCs, clarifies the relationship between autophagy and health status of MSCs and the effect of autophagic activity on MSCs senescence and IPF, providing a theoretical basis for promoting the clinical application of MSCs.

Metformin rejuvenates Nap1l2-impaired immunomodulation of bone marrow mesenchymal stem cells via metabolic reprogramming.

Ageing and cell senescence of mesenchymal stem cells (MSCs) limited their immunomodulation properties and therapeutic application. We previously reported that nucleosome assembly protein 1-like 2 (Nap1l2) contributes to MSCs senescence and osteogenic differentiation. Here, we sought to evaluate whether Nap1l2 impairs the immunomodulatory properties of MSCs and find a way to rescue the deficient properties. We demonstrated that metformin could rescue the impaired migration properties and T cell regulation properties of OE-Nap1l2 BMSCs. Moreover, metformin could improve the impaired therapeutic efficacy of OE-Nap1l2 BMSCs in the treatment of colitis and experimental autoimmune encephalomyelitis in mice. Mechanistically, metformin was capable of upregulating the activation of AMPK, synthesis of l-arginine and expression of inducible nitric oxide synthase in OE-Nap1l2 BMSCs, leading to an increasing level of nitric oxide. This study indicated that Nap1l2 negatively regulated the immunomodulatory properties of BMSCs and that the impaired functions could be rescued by metformin pretreatment via metabolic reprogramming. This strategy might serve as a practical therapeutic option to rescue impaired MSCs functions for further application.

Platelet-rich plasma-derived exosomes boost mesenchymal stem cells to promote peripheral nerve regeneration

Peripheral nerve injury (PNI) remains a severe clinical problem with debilitating consequences. Mesenchymal stem cell (MSC)-based therapy is promising, but the problems of poor engraftment and insufficient neurotrophic effects need to be overcome. Herein, we isolated platelet-rich plasma-derived exosomes (PRP-Exos), which contain abundant bioactive molecules, and investigated their potential to increase the regenerative capacity of MSCs. We observed that PRP-Exos significantly increased MSC proliferation, viability, and mobility, decreased MSC apoptosis under stress, maintained MSC stemness, and attenuated MSC senescence. In vivo, PRP-Exo-treated MSCs (pExo-MSCs) exhibited an increased retention rate and heightened therapeutic efficacy, as indicated by increased axonal regeneration, remyelination, and recovery of neurological function in a PNI model. In vitro, pExo-MSCs coculture promoted Schwann cell proliferation and dorsal root ganglion axon growth. Moreover, the increased neurotrophic behaviour of pExo-MSCs was mediated by trophic factors, particularly glia-derived neurotrophic factor (GDNF), and PRP-Exos activated the PI3K/Akt signalling pathway in MSCs, leading to the observed phenotypes. These findings demonstrate that PRP-Exos may be novel agents for increasing the ability of MSCs to promote neural repair and regeneration in patients with PNI.

MiR-873-5p Suppression Reinvigorates Aging Mesenchymal Stem Cells and Improves Cardiac Repair after Myocardial Infarction.

Aging poses obstacles to the functionality of human mesenchymal stem cells (MSCs), resulting in a notable decline in their valuable contribution to myocardial infarction (MI). MicroRNAs (miRNAs) play a pivotal role in governing MSC aging; nonetheless, the specific mechanisms remain puzzling. This research delved into the value of miR-873-5p in the management of MSC aging and investigated whether the restraint of miR-873-5p could regenerate aged MSCs (AMSCs), thereby enhancing their healing success for MI. In this study, MSCs were isolated from both young donors (referred to as YMSCs) and aged donors (referred to as AMSCs). The senescence status of these MSCs was evaluated through the application of age-related β-galactosidase (SA-β-gal) staining. Following this assessment, the MSCs, including those treated with anti-miR-873-5p-AMSCs, were then transplanted into the hearts of Sprague-Dawley rats experiencing acute myocardial infarction. Increasing miR-873-5p levels in YMSCs resulted in elevated cellular aging, whereas reducing miR-873-5p expression decreased aging in AMSCs. Mechanistically, miR-873-5p inhibited autophagy in MSCs through the AMPK signaling pathway, leading to cellular aging by suppressing the Cab39 expression. Partial alleviation of these effects was achieved by the administration of the autophagy inhibitor 3-methyladenine. Grafting of anti-miR-873-5p-AMSCs, by enhancing angiogenesis and bolstering cell survival, led to an improvement in cardiac function in the rat model, unlike the transplantation of AMSCs. miR-873-5p which serves as a pivotal element in mediating MSC aging through its regulation of the Cab39/AMPK signaling pathway. It represents an innovative target for revitalizing AMSCs and enhancing their heart-protective abilities.

Morphology-based deep learning enables accurate detection of senescence in mesenchymal stem cell cultures.

Cell senescence is a sign of aging and plays a significant role in the pathogenesis of age-related disorders. For cell therapy, senescence may compromise the quality and efficacy of cells, posing potential safety risks. Mesenchymal stem cells (MSCs) are currently undergoing extensive research for cell therapy, thus necessitating the development of effective methods to evaluate senescence. Senescent MSCs exhibit distinctive morphology that can be used for detection. However, morphological assessment during MSC production is often subjective and uncertain. New tools are required for the reliable evaluation of senescent single cells on a large scale in live imaging of MSCs. We have developed a successful morphology-based Cascade region-based convolution neural network (Cascade R-CNN) system for detecting senescent MSCs, which can automatically locate single cells of different sizes and shapes in multicellular images and assess their senescence state. Additionally, we tested the applicability of the Cascade R-CNN system for MSC senescence and examined the correlation between morphological changes with other senescence indicators. This deep learning has been applied for the first time to detect senescent MSCs, showing promising performance in both chronic and acute MSC senescence. The system can be a labor-saving and cost-effective option for screening MSC culture conditions and anti-aging drugs, as well as providing a powerful tool for non-invasive and real-time morphological image analysis integrated into cell production.

Age-Related Alterations in Mesenchymal Stem Cell Function: Understanding Mechanisms and Seeking Opportunities to Bypass the Cellular Aging.

Undoubtedly, mesenchymal stem cells (MSCs) are the most common cell therapy candidates in clinical research and therapy. They not only exert considerable therapeutic effects to alleviate inflammation and promote regeneration, but also show low-immunogenicity properties, which ensure their safety following allogeneic transplantation. Thanks to the necessity of providing a sufficient number of MSCs to achieve clinically efficient outcomes, prolonged in vitro cultivation is indisputable. However, either following long-term in vitro expansion or aging in elderly individuals, MSCs face cellular senescence. Senescent MSCs undergo an impairment in their function and therapeutic capacities and secrete degenerative factors which negatively affect young MSCs. To this end, designing novel investigations to further elucidate cellular senescence and to pave the way toward finding new strategies to reverse senescence is highly demanded. In this review, we will concisely discuss current progress on the detailed mechanisms of MSC senescence and various inflicted changes following aging in MSC. We will also shed light on the examined strategies underlying monitoring and reversing senescence in MSCs to bypass the comprised therapeutic efficacy of the senescent MSCs.

Mesenchymal stem cells with p38 mitogen-activated protein kinase interference ameliorate mouse ischemic stroke.

Mesenchymal stem cells (MSCs) have been widely used in the treatment of ischemic stroke. However, factors such as high glucose, oxidative stress, and aging can lead to the reduced function of donor MSCs. The p38 mitogen-activated protein kinase (MAPK) signaling pathway is associated with various functions, such as cell proliferation, apoptosis, senescence, differentiation, and paracrine secretion. This study examined the hypothesis that the downregulation of p38 MAPK expression in MSCs improves the prognosis of mice with ischemic stroke. Lentiviral vector-mediated short hairpin RNA (shRNA) was constructed to downregulate the expression level of p38 MAPK in mouse bone marrow-derived MSCs. The growth cycle, apoptosis, and senescence of MSCs after infection were examined. A mouse model of ischemic stroke was constructed. After MSC transplantation, the recovery of neurological function in the mice was evaluated. Lentivirus-mediated shRNA significantly downregulated the mRNA and protein expression levels of p38 MAPK. The senescence of MSCs in the p38 MAPK downregulation group was significantly reduced, but the growth cycle and apoptosis did not significantly change. Compared with the control group, the infarct volume was reduced, and the neurological function and the axonal remodeling were improved in mice with ischemic stroke after transplantation of MSCs with downregulated p38 MAPK. Immunohistochemistry confirmed that in the p38 MAPK downregulation group, apoptotic cells were reduced, and the number of neuronal precursors and the formation of white matter myelin were increased. In conclusion, downregulation of p38 MAPK expression in MSCs improves the therapeutic effect in mice with ischemic stroke, an effect that may be related to a reduction in MSC senescence. This method is expected to improve the efficacy of MSCs in patients, especially in patients with underlying diseases such as diabetes, thus providing a basis for clinical individualized treatment for cerebral infarction.

Cellular microenvironment: a key for tuning mesenchymal stem cell senescence.

Mesenchymal stem cells (MSCs) possess the ability to self-renew and differentiate into multiple cell types, making them highly suitable for use as seed cells in tissue engineering. These can be derived from various sources and have been found to play crucial roles in several physiological processes, such as tissue repair, immune regulation, and intercellular communication. However, the limited capacity for cell proliferation and the secretion of senescence-associated secreted phenotypes (SASPs) pose challenges for the clinical application of MSCs. In this review, we provide a comprehensive summary of the senescence characteristics of MSCs and examine the different features of cellular microenvironments studied thus far. Additionally, we discuss the mechanisms by which cellular microenvironments regulate the senescence process of MSCs, offering insights into preserving their functionality and enhancing their effectiveness.

RAB27B-regulated exosomes mediate LSC maintenance via resistance to senescence and crosstalk with the microenvironment.

The fate of leukaemia stem cells (LSCs) is determined by both their inherent mechanisms and crosstalk with their niches. Although LSCs were confirmed to be eradicated by restarting senescence, the specific key regulators of LSC resistance to senescence and remodelling of the niche to obtain a microenvironment suitable for stemness remain unknown. Here, we found that RAB27B, a gene regulating exosome secretion, was overexpressed in LSCs and associated with the poor prognosis of acute myeloid leukaemia (AML) patients. The increased RAB27B in LSCs prevented their senescence and maintained their stemness in vitro and in vivo. Mechanically, the increased RAB27B expression in LSCs selectively promoted the loading and release of exosomes rich in senescence-inducing proteins by direct combination. Furthermore, RAB27B-regulated LSC-derived exosomes remodelled the niche and induced senescence of mesenchymal stem cells (MSCs) with increased RAB27B expression ex vivo and in vivo. The increased RAB27B in the senescent MSCs conversely promoted LSC maintenance ex vivo and in vivo via selective excretion of exosomes rich in stemness-promoting proteins. Therefore, we identified the specifically increased RAB27B in LSCs and their educated senescent MSCs as a hub molecule for LSC resistance to senescence and maintenance through crosstalk with its niche via selective exosome excretion.

Mesenchymal Stem Cell in 3D Culture: Diminishing Cell Senescence in Cryopreservation and Long-term Expansion

Mesenchymal stem cells (MSCs) are widely recognized in cell treatment due to their capacity to secrete trophic factors, differentiate multipotent, and self-renew. Although there is growing evidence that MSCs have therapeutic benefits in various clinical settings, these cells eventually lose their ability to regenerate as they age, which increases cellular dysfunction. Several factors may affect MSCs aging, such as culture dimensions, cryopreservation process, and long-term expansion. Traditional two-dimensional (2D) culture conditions lack the complexities required to recreate MSCs in their natural environment. Meanwhile, three-dimensional (3D) culture mimics the niche, dynamic, and specialized microenvironments of the cells in vivo. The most used storage technique for MSCs, cryopreservation, requires a very low temperature reduction, which stresses cells and can cause the release of pro-inflammatory cytokines. For the utilization of MSCs in therapeutic applications, an in vitro expansion technique is required. Repeated expansion may reduce proliferative capacity, disrupts cellular shape, and impairs the somatic cell function of MSCs. Various processes and techniques may influence MSCs leading to cell aging. One of the culture methods, 3D culture, is shown to reduce the factors that will compromise the therapeutic effects of MSCs, especially cell senescence. The effect of culture dimensions, cryopreservation, and long-term expansion on cell senescence will be discussed in this review article.Keywords: cell aging, mesenchymal stem cell, 3D culture, cell senescence, cryopreservation, long-term expansion

Silencing circSERPINE2 restrains mesenchymal stem cell senescence via the YBX3/PCNA/p21 axis

Increasing evidence indicates that circular RNAs (circRNAs) accumulate in aging tissues and nonproliferating cells due to their high stability. However, whether upregulation of circRNA expression mediates stem cell senescence and whether circRNAs can be targeted to alleviate aging-related disorders remain unclear. Here, RNA sequencing analysis of differentially expressed circRNAs in long-term-cultured mesenchymal stem cells (MSCs) revealed that circSERPINE2 expression was significantly increased in late passages. CircSERPINE2 small interfering RNA delayed MSC senescence and rejuvenated MSCs, while circSERPINE2 overexpression had the opposite effect. RNA pulldown followed by mass spectrometry revealed an interaction between circSERPINE2 and YBX3. CircSERPINE2 increased the affinity of YBX3 for ZO-1 through the CCAUC motif, resulting in the sequestration of YBX3 in the cytoplasm, inhibiting the association of YBX3 with the PCNA promoter and eventually affecting p21 ubiquitin-mediated degradation. In addition, our results demonstrated that senescence-related downregulation of EIF4A3 gave rise to circSERPINE2. In vivo, intra-articular injection of si-circSerpine2 restrained native joint-resident MSC senescence and cartilage degeneration in mice with aging-related osteoarthritis. Taken together, our findings provide strong evidence for a regulatory role for the circSERPINE2/YBX3/PCNA/p21 axis in MSC senescence and the therapeutic potential of si-circSERPINE2 in alleviating aging-associated syndromes, such as osteoarthritis.