Prediction of Age-Related MicroRNA Signature in Mesenchymal Stem Cells by using Computational Methods.

BACKGROUND: Aging is a phenomenon which occurs over time and leads to the decay of living organisms. During the progression of aging, some age-associated diseases including cardiovascular disease, cancers, and neurological, mental, and physical disorders could develop. Genetic and epigenetic factors like microRNAs, as one of the post-transcriptional regulators of genes, play important roles in senescence. The self-renewal and differentiation capacity of mesenchymal stem cells makes them good candidates for regenerative medicine. OBJECTIVE: The objective of this study is to evaluate senescence-related miRNAs in human MSCs using bioinformatics analysis. METHODS: In this study, the Gene Expression Omnibus (GEO) database was used to investigate the senescence-related genome profile. Then, down-regulated genes were selected for further bioinformatics analysis with the assumption that their decreased expression is associated with an increased aging process. Considering that miRNAs can interfere in gene expression, miRNAs complementary to these genes were identified using bioinformatics software. RESULTS: Through bioinformatics analysis, we predicted hsa-miR-590-3p, hsa-miR-10b-3p, hsamiR- 548 family, hsa-miR-144-3p, and hsa-miR-30b-5p which involve in cellular senescence and the aging of human MSCs. CONCLUSION: miRNA mimics or anti-miRNA agents have the potential to be used as anti-aging tools for MSCs.

Mechanisms underlying low-clinical responses to PD-1/PD-L1 blocking antibodies in immunotherapy of cancer: a key role of exosomal PD-L1.

Exosomes, as the main group of extracellular vesicles, are biologically active lipid-bilayer vesicles that are naturally released from different types of normal or tumor cells. These vesicles play an important role in intercellular communication and influence the extracellular environment and the immune system. Emerging evidence demonstrates that cancer-derived exosomes are enriched in immunosuppressive proteins, such as the programmed death-ligand 1 (PD-L1). PD-L1 and its receptor programmed cell death protein 1 (PD-1) are the key immune checkpoint molecules that promote tumor progression via negative regulation of immune responses. PDL-1 is highly expressed on the surface of tumor cells and binds to PD-1 on the surface of activated T cells, leading to suppression of T cells, which consequently enables cancer cells to escape antitumor immunity. Currently, there are several Food and Drug Administration-approved monoclonal antibodies blocking PD-1/PD-L1 interaction, which are clinically used for cancer treatment. However, despite impressive treatment outcomes, some patients show poor response to PD-1/PD-L1 blockade. Of note, tumor-derived exosomes containing PD-L1 can recapitulate the effect of cell-surface PD-L1. There is evidence that reveals a significant association between levels of circulating exosomal PD-L1 and rate of response to anti-PD-1/PD-L1 antibody therapy. The present article reviews the role of exosomal PDL-1 in the therapeutic resistance to anti-PD-1/PD-L1 treatment. Importantly, it is suggested that the removal of exosomal PDL-1 could serve as a therapeutic adjuvant for enhancing the efficacy of anti-PD-1/PD-L1 therapy in patients with cancer.