Cellular In Vitro Responses Induced by Human Mesenchymal Stem/Stromal Cell-Derived Extracellular Vesicles Obtained from Suspension Culture.

Mesenchymal stem/stromal cells (MSCs) and their extracellular vesicles (MSC-EVs) have been described to have important roles in tissue regeneration, including tissue repair, control of inflammation, enhancing angiogenesis, and regulating extracellular matrix remodeling. MSC-EVs have many advantages for use in regeneration therapies such as facility for dosage, histocompatibility, and low immunogenicity, thus possessing a lower possibility of rejection. In this work, we address the potential activity of MSC-EVs isolated from adipose-derived MSCs (ADMSC-EVs) cultured on cross-linked dextran microcarriers, applied to test the scalability and reproducibility of EV production. Isolated ADMSC-EVs were added into cultured human dermal fibroblasts (NHDF-1), keratinocytes (HaCat), endothelial cells (HUVEC), and THP-1 cell-derived macrophages to evaluate cellular responses (i.e., cell proliferation, cell migration, angiogenesis induction, and macrophage phenotype-switching). ADMSC viability and phenotype were assessed during cell culture and isolated ADMSC-EVs were monitored by nanotracking particle analysis, electron microscopy, and immunophenotyping. We observed an enhancement of HaCat proliferation; NHDF-1 and HaCat migration; endothelial tube formation on HUVEC; and the expression of inflammatory cytokines in THP-1-derived macrophages. The increased expression of TGF-ß and IL-1ß was observed in M1 macrophages treated with higher doses of ADMSC-EVs. Hence, EVs from microcarrier-cultivated ADMSCs are shown to modulate cell behavior, being able to induce skin tissue related cells to migrate and proliferate as well as stimulate angiogenesis and cause balance between pro- and anti-inflammatory responses in macrophages. Based on these findings, we suggest that the isolation of EVs from ADMSC suspension cultures makes it possible to induce in vitro cellular responses of interest and obtain sufficient particle numbers for the development of in vivo concept tests for tissue regeneration studies.

The Nuclear RNA-binding Protein RBSR1 Interactome in Trypanosoma cruzi.

Trypanosoma cruzi, the etiological agent of Chagas disease, has been widely studied, reflecting both its medical importance and the particular features that make this pathogen an attractive model for basic biological studies. The repression of transcripts by messenger ribonucleoprotein (mRNP) complexes is an important pathway of post-transcriptional regulation in eukaryotes, including T. cruzi. RBSR1 is a serine-arginine (SR)-rich RNA-binding protein (RBP) in T. cruzi that contains one RNA-recognition motif (RRM); this protein has a primarily nuclear localization and is developmentally regulated, not being detected in metacyclic trypomastigotes. RBSR1 interacts with other RBPs, such as UBP1 and UBP2, and the nuclear SR-protein TRRM1. Phylogenetic analysis indicated that RBSR1 is orthologous to the human splicing factor SRSF7, what might indicate its possible involvement in pre-RNA processing. Accordingly, ribonomics data showed the enrichment of snoRNAs and snRNAs in the RBSR1 immunoprecipiatation complex, hence reinforcing the supposition that this protein might be involved in RNA processing in the nucleus.

Morphological and pathogenic investigation of the emerging fungal threat Emergomyces africanus.

Emergomyces africanus is a highly fatal fungal pathogen affecting individuals with advanced HIV disease. Molecular patterns and ultrastructural aspects of E. africanus are unknown, and pathogenic models have not been investigated in detail. Since the cell wall of fungi is a determinant for interaction with the host and antifungal development, we characterized the ultrastructural aspects of E. africanus and the general properties of cell wall components under different conditions of growth in vitro and in vivo. We also tested the pathogenic potential of E. africanus in a Galleria mellonella model of infection. Transmission electron microscopy revealed the common intracellular, ultrastructural features of fungi in association with a thick cell wall. Scanning electron microscopy revealed a smooth cell surface, with no apparent decorative structures. Yeast cultures of E. africanus showed the distribution of chitin, chitooligomers, and mannoproteins commonly observed in fungi. However, in mixed microenvironments containing yeast and filamenting forms of E. africanus, the detection of chitooligomers was increased in comparison with isolated yeast cells, while the detection of these components in filamenting forms was markedly reduced. These observations were suggestive of the ability of E. africanus to change its cell wall composition in response to different microenvironments. Although E. africanus was unable to kill G. mellonella, this infection model allowed us to isolate infected hemocytes for further analysis of mannoproteins, chitin, and chitooligomers. Once again, the detection of E. africanus chitooligomers was markedly increased. These results reveal previously unknown ultrastructural features of E. africanus and suggest a high plasticity in the cell wall of this lethal pathogen. IMPORTANCE: The epidemiology of fungal infections is very dynamic, and novel health emergencies are hard to predict. New fungal pathogens have been continuously emerging for the last few decades, and Emergomyces africanus is one of these threats to human health. This complex scenario points to the need for generating knowledge about emerging pathogens so that new therapeutic strategies can be designed. In this study, we characterized the general cellular and pathogenic properties of the emerging fungal pathogen E. africanus. Our results reveal that E. africanus manifests some of the typical properties of fungal cells but also exhibits some unique characteristics that might be helpful for the future development of therapeutic strategies.

Adipogenesis, Osteogenesis, and Chondrogenesis of Human Mesenchymal Stem/Stromal Cells: A Comparative Transcriptome Approach.

Adipogenesis, osteogenesis and chondrogenesis of human mesenchymal stem/stromal cells (MSC) are complex and highly regulated processes. Over the years, several studies have focused on understanding the mechanisms involved in the MSC commitment to the osteogenic, adipogenic and/or chondrogenic phenotypes. High-throughput methodologies have been used to investigate the gene expression profile during differentiation. Association of data analysis of mRNAs, microRNAs, circular RNAs and long non-coding RNAs, obtained at different time points over these processes, are important to depict the complexity of differentiation. This review will discuss the results that were highlighted in transcriptome analyses of MSC undergoing adipogenic, osteogenic and chondrogenic differentiation. The focus is to shed light on key molecules, main signaling pathways and biological processes related to different time points of adipogenesis, osteogenesis and chondrogenesis.

Data describing the experimental design and quality control of RNA-Seq of human adipose-derived stem cells undergoing early adipogenesis and osteogenesis.

An important tool to study the regulation of gene expression is the sequencing and the analysis of different RNA fractions: total, ribosome-free, monosomal and polysomal. By comparing these different populations, it is possible to identity which genes are differentially expressed and to get information on how transcriptional and translational regulation modulates cellular function. Therefore, we used this strategy to analyze the regulation of gene expression of human adipose-derived stem cells during the triggering of the adipogenic and osteogenic differentiation. Here, we have focused on analyzing the differential expression of mRNAs during early adipogenic and osteogenic differentiation, and presented the detailed data concerning the experimental design, the RNA-Seq quality data, the raw data obtained and the RT-qPCR validation data. This information is important to confirm the accuracy of the data considering a future reuse of the data provided. Moreover, this study may be used as groundwork for future characterization of the transcriptome and the translatome regulation of different cell types.

Visible-light reduced silver nanoparticles' toxicity in Allium cepa test system.

Silver nanoparticles (AgNPs) are widely used in consumer products due to their antibacterial property; however, their potential toxicity and release into the environment raises concern. Based on the limited understanding of AgNPs aggregation behavior, this study aimed to investigate the toxicity of uncoated (uc-AgNP) and coated with polyvinylpyrrolidone (PVP-AgNP), at low concentrations (0.5-100 ng/mL), under dark and visible-light exposure, using a plant test system. We exposed Allium cepa seeds to both types of AgNPs for 4-5 days to evaluate several toxicity endpoints. AgNPs did not cause acute toxicity (i.e., inhibition of seed germination and root development), but caused genotoxicity and biochemical alterations in oxidative stress parameters (lipid peroxidation) and activities of antioxidant enzymes (superoxide dismutase and catalase) in light and dark conditions. However, the light exposure decreased the rate of chromosomal aberration and micronuclei up to 5.60x in uc-AgNP and 2.01x in PVP-AgNP, and 2.69x in uc-AgNP and 3.70x in PVP-AgNP, respectively. Thus, light exposure reduced the overall genotoxicity of these AgNPs. In addition, mitotic index alterations and morphoanatomical changes in meristematic cells were observed only in the dark condition at the highest concentrations, demonstrating that light also reduces AgNPs cytotoxicity. The light-dependent aggregation of AgNPs may have reduced toxicity by reducing the uptake of these NPs by the cells. Our findings demonstrate that AgNPs can be genotoxic, cytotoxic and induce morphoanatomical and biochemical changes in A. cepa roots even at low concentrations, and that visible-light alters their aggregation state, and decreases their toxicity. We suggest that visible light can be an alternative treatment to remediate AgNP residues, minimizing their toxicity and environmental risks.

Cell cycle genes are downregulated after adipogenic triggering in human adipose tissue-derived stem cells by regulation of mRNA abundance.

The adipogenic process is characterized by the expression of adipocyte differentiation markers that lead to changes in cell metabolism and to the accumulation of lipid droplets. Moreover, during early adipogenesis, cells undergo a strong downregulation of translational activity with a decrease in cell size, proliferation and migration. In the present study, we identified that after 24 hours of adipogenic induction, human adipose tissue-derived stem cells (hASCs) undergo a G1-cell cycle arrest consistent with reduced proliferation, and this effect was correlated with a shift in polysome profile with an enrichment of the monosomal fraction and a reduction of the polysomal fraction. Polysome profiling analysis also revealed that this change in the monosomal/polysomal ratio was related to a strong downregulation of cell cycle and proliferation genes, such as cyclins and cyclin-dependent kinases (CDKs). Comparing total and polysome-associated mRNA sequencing, we also observed that this downregulation was mostly due to a reduction of cell cycle and proliferation transcripts via control of total mRNA abundance, rather than by translational control.

The Protein Content of Extracellular Vesicles Derived from Expanded Human Umbilical Cord Blood-Derived CD133+ and Human Bone Marrow-Derived Mesenchymal Stem Cells Partially Explains Why both Sources are Advantageous for Regenerative Medicine.

Adult stem cells have beneficial effects when exposed to damaged tissue due, at least in part, to their paracrine activity, which includes soluble factors and extracellular vesicles (EVs). Given the multiplicity of signals carried by these vesicles through the horizontal transfer of functional molecules, human mesenchymal stem cell (hMSCs) and CD133+ cell-derived EVs have been tested in various disease models and shown to recover damaged tissues. In this study, we profiled the protein content of EVs derived from expanded human CD133+ cells and bone marrow-derived hMSCs with the intention of better understanding the functions performed by these vesicles/cells and delineating the most appropriate use of each EV in future therapeutic procedures. Using LC-MS/MS analysis, we identified 623 proteins for expanded CD133+-EVs and 797 proteins for hMSCs-EVs. Although the EVs from both origins were qualitatively similar, when protein abundance was considered, hMSCs-EVs and CD133+-EVs were different. Gene Ontology (GO) enrichment analysis in CD133+-EVs revealed proteins involved in a variety of angiogenesis-related functions as well proteins related to the cytoskeleton and highly implicated in cell motility and cellular activation. In contrast, when overrepresented proteins in hMSCs-EVs were analyzed, a GO cluster of immune response-related genes involved with immune response-regulating factors acting on phagocytosis and innate immunity was identified. Together our data demonstrate that from the point of view of protein content, expanded CD133+-EVs and hMSCs-EVs are in part similar but also sufficiently different to reflect the main beneficial paracrine effects widely reported in pre-clinical studies using expanded CD133+ cells and/or hBM-MSCs.

Downregulation of the protein synthesis machinery is a major regulatory event during early adipogenic differentiation of human adipose-derived stromal cells.

Commitment of adult stem cells involves the activation of specific gene networks regulated from transcription to protein synthesis. Here, we used ribosome profiling to identify mRNAs regulated at the translational level, through both differential association to polysomes and modulation of their translational rates. We observed that translational regulation during the differentiation of human adipose-derived stromal cells (hASCs, also known as adipose-derived mesenchymal stem cells), a subset of which are stem cells, to adipocytes was a major regulatory event. hASCs showed a significant reduction of whole protein synthesis after adipogenic induction and a downregulation of the expression and translational efficiency of ribosomal proteins. Additionally, focal adhesion and cytoskeletal proteins were downregulated at the translational level. This negative regulation of the essential biological functions of hASCs resulted in a reduction in cell size and the potential of hASCs to migrate. We analyzed whether the inactivation of key translation initiation factors was involved in this observed major repression of translation. We showed that there was an increase in the hypo phosphorylated forms of 4E-BP1, a negative regulator of translation, during early adipogenesis. Our results showed that extensive translational regulation occurred during the early stage of the adipogenic differentiation of hASCs.