CD137 Regulates Bone Loss via the p53 Wnt/β-Catenin Signaling Pathways in Aged Mice

Emerging Landscape of Mesenchymal Stem Cell Senescence Mechanisms and Implications on Therapeutic Strategies

Mesenchymal stem cells (MSCs) hold significant promise for regenerative medicine and tissue engineering due to their unique multipotent differentiation ability and immunomodulatory properties. MSC therapy is widely discussed and utilized in clinical treatment. However, during both in vitro expansion and in vivo transplantation, MSCs are prone to senescence, an irreversible growth arrest characterized by morphological, gene expression, and functional changes in genomic regulation. The microenvironment surrounding MSCs plays a crucial role in modulating their senescence phenotype, influenced by factors such as hypoxia, inflammation, and aging status. Numerous strategies targeting MSC senescence have been developed, including senolytics and senomorphic agents, antioxidant and exosome therapies, mitochondrial transfer, and niche modulation. Novel approaches addressing replicative senescence have also emerged. This paper comprehensively reviews the current molecular manifestations of MSC senescence, addresses the environmental impact on senescence, and highlights potential therapeutic strategies to mitigate senescence in MSC-based therapies. These insights aim to enhance the efficacy and understanding of MSC therapies.

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.

Leptin deficiency impairs adipogenesis and browning response in mouse mesenchymal progenitors

Although phenotypically different, brown adipose tissue (BAT) and inguinal white adipose tissue (iWAT) are able to produce heat through non-shivering thermogenesis due to the presence of mitochondrial uncoupling protein 1 (UCP1). The appearance of thermogenically active beige adipocytes in iWAT is known as browning. Both brown and beige cells originate from mesenchymal stem cells (MSCs), and in culture conditions a browning response can be induced with hypothermia (i.e. 32 °C) during which nuclear leptin immunodetection was observed. The central role of leptin in regulating food intake and energy consumption is well recognised, but its importance in the browning process at the cellular level is unclear. Here, immunocytochemical analysis of MSC-derived adipocytes established nuclear localization of both leptin and leptin receptor suggesting an involvement of the leptin pathway in the browning response. In order to elucidate whether leptin modulates the expression of brown and beige adipocyte markers, BAT and iWAT samples from leptin-deficient (ob/ob) mice were analysed and exhibited reduced brown/beige marker expression compared to wild-type controls. When MSCs were isolated and differentiated into adipocytes, leptin deficiency was observed to induce a white phenotype, especially when incubated at 32 °C. These adaptations were accompanied with morphological signs of impaired adipogenic differentiation. Overall, our results indicate that leptin supports adipocyte browning and suggest a potential role for leptin in adipogenesis and browning.

Screening for MicroRNA combination with engineered exosomes as a new tool against osteosarcoma in elderly patients

The most common primary malignant bone sarcoma is Osteogenic sarcoma (OS) which has a bimodal age distribution. Unfortunately, the treatment of OS was less effective for elderly patients than for younger ones. The study aimed to explore a new microRNA (miRNA) which can bind to combining engineered exosomes for treatment of older OS patients. Based on GSE65071 and miRNet 2.0, two up-regulated miRNAs (miR-328, miR-107) and seven down-regulated miRNAs (miR-133b, miR-206, miR-1-3p, miR-133a, miR-449a, miR-181daysay, miR-134) were selected. Next, we used FunRich software to predict the up-stream transcription factors (TFs) of differentially expressed miRNAs (DE-miRNAs). By comparing target genes predicted from DE-miRNAs with differentially expressed genes, we identified 12 down-regulated and 310 up-regulated mRNAs. For KEGG analysis, the most enriched KEGG pathway was Cell cycle, Spliceosome, and Protein digestion and absorption. By using protein-protein interactions network, topological analysis algorithm and GEPIA database, miR-449a /CCNB1 axis was identified. Experiments in vitro were conducted to confirm the results too. MiRNA-449a is down-regulated in osteosarcoma and suppresses cell proliferation by targeting CCNB1. Our findings not only reveal a novel mechanism of miR-449a /CCNB1 in OS but also had laid the groundwork for further investigation and analysis in the field of exosome engineering.

Integrated Bioinformatics and Experimental Analysis Identified TRIM28 a Potential Prognostic Biomarker and Correlated with Immune Infiltrates in Liver Hepatocellular Carcinoma

Background

Since the 1970s, liver hepatocellular carcinoma (LIHC) has experienced a constant rise in incidence and mortality rates, making the identification of LIHC biomarkers very important. Tripartite Motif-Containing 28 (TRIM28) is a protein-coding gene which encodes the tripartite motif-containing proteins (TRIMs) family and is associated with specific chromatin regions. TRIM28 expression and its prognostic value and impact on the immune system in LIHC patients are being investigated for the first time.

Methods

The TRIM28 expression data from TCGA database was used to analyze TRIM28 expression, clinicopathological information, gene enrichment, and immune infiltration and conduct additional bioinformatics analysis. R language was used for statistical analysis. TIMER, CIBERSORT, and ssGSEA were used to assess immune responses of TRIM28 in LIHC. Next, the results were validated using GEPIA, ROC analysis, and immunohistochemical staining pictures from the THPA. GSE14520, GSE63898, and GSE87630 datasets were analyzed using ROC analysis to further evaluate TRIM28's diagnostic value. To ultimately determine TRIM28 expression, we performed qRT-PCR (quantitative real-time polymerase chain reaction).

Results

High TRIM28 expression level was associated with T classification, pathologic stage, histologic grade, and serum AFP levels. In patients with LIHC, TRIM28 was an independent risk factor for a poor prognosis. The pathways ligand-receptor interaction, which is critical in LIHC patients, were closely associated with TRIM28 expression, and the function of DC could be suppressed by overexpression of TRIM28. As a final step, our results were validated by GEO data and qRT-PCR.

Conclusions

TRIM28 will shed new light on LIHC mechanisms. As an effective diagnostic and intervention tool, this gene will be able to diagnose and treat LIHC at an early stage.

Identification of hub genes for early detection of bone metastasis in breast cancer

BACKGROUND

Globally, among all women, the most frequently detected and diagnosed and the most lethal type of cancer is breast cancer (BC). In particular, bone is one of the most frequent distant metastases 24in breast cancer patients and bone metastasis arises in approximately 80% of advanced patients. Thus, we need to identify and validate early detection markers that can differentiate metastasis from non-metastasis breast cancers.

METHODS

GSE55715, GSE103357, and GSE146661 gene expression profiling data were downloaded from the GEO database. There was 14 breast cancer with bone metastasis samples and 8 breast cancer tissue samples. GEO2R was used to screen for differentially expressed genes (DEGs). The volcano plots, Venn diagrams, and annular heatmap were generated by using the ggplot2 package. By using the cluster Profiler R package, KEGG and GO enrichment analyses of DEGs were conducted. Through PPI network construction using the STRING database, key hub genes were identified by cytoHubba. Finally, K-M survival and ROC curves were generated to validate hub gene expression.

RESULTS

By GO enrichment analysis, 143 DEGs were enriched in the following GO terms: extracellular structure organization, extracellular matrix organization, leukocyte migration class II protein complex, collagen tridermic protein complex, extracellular matrix structural constituent, growth factor binding, and platelet-derived growth factor binding. In the KEGG pathway enrichment analysis, DEGs were enriched in Staphylococcus aureus infection, Complement and coagulation cascades, and Asthma. By PPI network analysis, we selected the top 10 genes, including SLCO2B1, STAB1, SERPING1, HLA-DOA, AIF1, GIMAP4, C1orf162, HLA-DMB, ADAP2, and HAVCR2. By using TCGA and THPA databases, we validated 2 genes, SERPING1 and GIMAP4, that were related to the early detection of bone metastasis in BC.

CONCLUSIONS

2 abnormally expressed hub genes could play a pivotal role in the breast cancer with bone metastasis by affecting bone homeostasis imbalance in the bone microenvironment.