Abstract Bone microenvironment provides growth and survival signals essential for osteosarcoma (OS) initiation and progression. OS cells regulate communications inside tumor microenvironment through different ways and, among all, tumor-derived exosomes support cancer progression and metastasis. To define the contribution of OS-derived exosomes inside the microenvironment, we investigated the effects induced in bone remodeling mechanism and tumor angiogenesis. We demonstrated that exosomes promoted osteoclasts differentiation and bone resorption activity. Furthermore, exosomes potentiated tube formation of endothelial cells and increased angiogenic markers expression. We therefore investigated the micro RNA (miRNA) cargo from exosomes and their parental cells by performing small RNA sequencing through NGS Illumina platform. Hierarchical clustering highlighted a unique molecular profile of exosomal miRNA; bioinformatic analysis by DIANA-mirPath revealed that miRNAs identified take part in various biological processes and carcinogenesis. Among these miRNAs, some were already known for their involvement in the tumor microenvironment establishment, as miR-148a and miR-21-5p. Enforced expression of miR-148a and miR-21-5p in Raw264.7 and hTert immortalized umbilical vein endothelial cells recapitulated the effects induced by exosomes. Overall, our study highlighted the importance of OS exosomes in tumor microenvironment also by a specific packaging of miRNAs.

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Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), is modifying human activity all over the world with significant health and economic burden. The advent of the SARS-CoV-2 pandemic prompted the scientific community to learn the virus dynamics concerning transmissibility, epidemiology, and usefulness of vaccines in fighting emerging health hazards. Pieces of evidence suggest that the first and second doses of mRNA vaccines induce a significant antibody response in vaccinated subjects or patients who recovered from SARS-CoV-2 infection, demonstrating the importance of the previously formed memory. The aim of this work has been to investigate the effects of BNT162b2 Pfizer-BioNTech mRNA-based vaccine booster dose in a cohort of 11 uninfected immunocompetent (ICs), evaluating the humoral and cellular responses, with more carefulness on memory B and T cells. Our findings underscore the potential benefit of the third dose of mRNA vaccine on the lifespan of memory B and T cells, suggesting that booster doses could increase protection against SARS-CoV-2 infection.

One of the goals of personalized medicine is to understand and treat diseases with greater precision through the molecular profile of the patient. This profiling is becoming a powerful tool for the discovery of novel biomarkers that can guide physicians in assessing, in advance, the disease stage, and monitoring disease progression. Circulating miRNAs and exosomal miRNAs, a group of small non-coding RNAs, are considered the gold standard diagnostic biomarkers for human diseases. We have previously demonstrated that osteosarcoma-derived exosomes are able to influence crucial mechanisms inside tumor niches, inducing osteoclast differentiation, and sustaining bone resorption activity. Here we discovered, through Next-Generation Sequencing (NGS), eight novel microRNAs in three different osteosarcoma cell lines, and assessed the selective packaging into the exosomes released. We then investigated, as proof-of-principle, the presence of the novel microRNAs in osteosarcoma patient samples, and found that 5 of the 8 novel microRNAs were more present in circulating exosomes of osteosarcoma patients compared with the controls. These results raise a question: Could the 8 novel microRNAs play a role for osteosarcoma pathogenesis? Although still premature, the results are encouraging, and further studies with a validation in a larger cohort are needed.