The tumor microenvironment represents a complex network, in which tumor cells not only communicate with each other but also with stromal and immune cells. Current research has demonstrated the vital role of the tumor microenvironment in supporting tumor phenotype via a sophisticated system of intercellular communication through direct cell-to-cell contact or by classical paracrine signaling loops of cytokines or growth factors. Recently, extracellular vesicles have emerged as an important mechanism of cellular interchange of bioactive molecules. Extracellular vesicles isolated from tumor and stromal cells have been implicated in various steps of tumor progression, such as proliferation, angiogenesis, metastasis, and drug resistance. Inhibition of extracellular vesicles secretion, and thus of the transfer of oncogenic molecules, holds promise for preventing tumor growth and drug resistance. This review focuses on the role of extracellular vesicles in modulating the tumor microenvironment by addressing different aspects of the bidirectional interactions among tumor and tumor-associated cells. The contribution of extracellular vesicles to drug resistance will also be discussed as well as therapeutic strategies targeting extracellular vesicles production for the treatment of cancer.

The role of the mesenchymal stromal cell- (MSC-) derived secretome is becoming increasingly intriguing from a clinical perspective due to its ability to stimulate endogenous tissue repair processes as well as its effective regulation of the immune system, mimicking the therapeutic effects produced by the MSCs. The secretome is a composite product secreted by MSC in vitro (in conditioned medium) and in vivo (in the extracellular milieu), consisting of a protein soluble fraction (mostly growth factors and cytokines) and a vesicular component, extracellular vesicles (EVs), which transfer proteins, lipids, and genetic material. MSC-derived secretome differs based on the tissue from which the MSCs are isolated and under specific conditions (e.g., preconditioning or priming) suggesting that clinical applications should be tailored by choosing the tissue of origin and a priming regimen to specifically correct a given pathology. MSC-derived secretome mediates beneficial angiogenic effects in a variety of tissue injury-related diseases. This supports the current effort to develop cell-free therapeutic products that bring both clinical benefits (reduced immunogenicity, persistence in vivo, and no genotoxicity associated with long-term cell cultures) and manufacturing advantages (reduced costs, availability of large quantities of off-the-shelf products, and lower regulatory burden). In the present review, we aim to give a comprehensive picture of the numerous components of the secretome produced by MSCs derived from the most common tissue sources for clinical use (e.g., AT, BM, and CB). We focus on the factors involved in the complex regulation of angiogenic processes.

MethodsViruses. We used the dual-tropic R5X4 strain 89.6 and macrophage-tropic (Mtropic) R5 strains SF162 and JR-FL (21,

The early mechanisms by which DNA-dependent immunization occurs remain poorly understood. We determined whether intradermal injection of a cytomegalovirus (CMV) promoter-driven plasmid encoding hen egg lysozyme (pCMV:HEL) induced sensitization against the encoded protein, and whether cutaneous dendritic cells (DC) were involved in this sensitization. Both humoral and cellular responses to HEL were observed. DC that migrated from skin explant culture 3 days after injection of pCMV:HEL DNA contained mRNA encoding HEL. They induced a 3.5-7-fold increase in [3H]thymidine incorporation by HEL protein-primed CD4+ T cells compared to that induced by DC from mice injected with control plasmid. DC emigrating from skin explants recovered from pCMV:HEL injected mice also sensitized naive mice after adoptive transfer and induced the generation of CTL. Thus following DNA delivery within the dermis, DC can induce primary and secondary immune responses.

There is a critical unmet need to detect and image 2D materials within single cells and tissues while surveying a high degree of information from single cells. Here, a versatile multiplexed label‐free single‐cell detection strategy is proposed based on single‐cell mass cytometry by time‐of‐flight (CyTOF) and ion‐beam imaging by time‐of‐flight (MIBI‐TOF). This strategy, “Label‐free sINgle‐cell tracKing of 2D matErials by mass cytometry and MIBI‐TOF Design” (LINKED), enables nanomaterial detection and simultaneous measurement of multiple cell and tissue features. As a proof of concept, a set of 2D materials, transition metal carbides, nitrides, and carbonitrides (MXenes), is selected to ensure mass detection within the cytometry range while avoiding overlap with more than 70 currently available tags, each able to survey multiple biological parameters. First, their detection and quantification in 15 primary human immune cell subpopulations are demonstrated. Together with the detection, mass cytometry is used to capture several biological aspects of MXenes, such as their biocompatibility and cytokine production after their uptake. Through enzymatic labeling, MXenes’ mediation of cell–cell interactions is simultaneously evaluated. In vivo biodistribution experiments using a mixture of MXenes in mice confirm the versatility of the detection strategy and reveal MXene accumulation in the liver, blood, spleen, lungs, and relative immune cell subtypes. Finally, MIBI‐TOF is applied to detect MXenes in different organs revealing their spatial distribution. The label‐free detection of 2D materials by mass cytometry at the single‐cell level, on multiple cell subpopulations and in multiple organs simultaneously, will enable exciting new opportunities in biomedicine.

The development of prophylactic and therapeutic agents for coronavirus disease 2019 (COVID-19) is a current global health priority. Here, we investigated the presence of cross-neutralizing antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in dromedary camels that were Middle East respiratory syndrome coronavirus (MERS-CoV) seropositive but MERS-CoV free. The tested 229 dromedaries had anti–MERS-CoV camel antibodies with variable cross-reactivity patterns against SARS-CoV-2 proteins, including the S trimer and M, N, and E proteins. Using SARS-CoV-2 competitive immunofluorescence immunoassays and pseudovirus neutralization assays, we found medium-to-high titers of cross-neutralizing antibodies against SARS-CoV-2 in these animals. Through linear B cell epitope mapping using phage immunoprecipitation sequencing and a SARS-CoV-2 peptide/proteome microarray, we identified a large repertoire of Betacoronavirus cross-reactive antibody specificities in these dromedaries and demonstrated that the SARS-CoV-2–specific VHH antibody repertoire is qualitatively diverse. This analysis revealed not only several SARS-CoV-2 epitopes that are highly immunogenic in humans, including a neutralizing epitope, but also epitopes exclusively targeted by camel antibodies. The identified SARS-CoV-2 cross-neutralizing camel antibodies are not proposed as a potential treatment for COVID-19. Rather, their presence in nonimmunized camels supports the development of SARS-CoV-2 hyperimmune camels, which could be a prominent source of therapeutic agents for the prevention and treatment of COVID-19.

The present study sought to determine how usage of coreceptors by human immunodeficiency virus type 1 dictates cell tropism and depletion of CD4 ؉ T cells in human lymphoid tissues cultured ex vivo. We found that coreceptor preferences control the marked, preferential depletion of coreceptor-expressing CD4 ؉ lymphocytes. In addition, there was a strong, but not absolute, preference shown by CXCR4-using strains for lymphocytes and by CCR5-using strains for macrophages.The hallmark of human immunodeficiency virus type 1 (HIV-1) disease is the progressive depletion of CD4 ϩ lymphocytes. Different strains of HIV vary with respect to their target cell range and cytopathic potential. The molecular basis for differential cell tropism and virulence remained obscure until the discovery of select chemokine receptors that act as essential cofactors for cellular entry by HIV-1 (1). We previously reported that HIV-1 envelope glycoprotein (gp120) determinants controlling a preference for CXCR4 resulted in marked depletion of CD4 ϩ T cells in human lymphoid histocultures, while those specifying a preference for CCR5 resulted in only mild depletion of such cells. These results suggested that either X4 viruses are intrinsically more cytopathic than R5 viruses or viruses with different coreceptor specificities target quantitatively distinct CD4 ϩ T-cell pools. Our earlier study established that R5 HIV-1 variants exclusively deplete CCR5-expressing CD4 ϩ lymphocytes, while X4 HIV-1 variants preferentially deplete CXCR4-expressing cells (5). However, the diverse HIV-1 isolates used in this work differed from each other by many parameters other than coreceptor usage that could influence cytopathicity.The present study sought to establish a specific causative relationship among coreceptor usage, tropism, and CD4 ϩ Tcell depletion in mature lymphoid tissue. Human tonsil histocultures were inoculated with pairs of recombinant strains of HIV-1 that differ exclusively in small regions of gp120 that control coreceptor preference. Three pairs of viruses based on an isogenic (NL4-3) viral backbone were studied: (i) NL4-3 (X4) and 49-5 (R5), virus chimeras that differ only in the gp120 V3 loop region that specifies strict reciprocal tropism for CXCR4 and CCR5, respectively (9, 12, 13); (ii) 134 (X4) and 126 (R5), site-directed mutants that differ in a single V3 amino acid residue that likewise dictates preference for CXCR4 or CCR5, respectively (3, 12); and 123 (X4) and USV3 (R5), chimeras that contain V3 loop segments derived from primary X4 and R5 viral isolates (references 3 and 12 and unpublished data).T-cell depletion and viral replication were measured 12 to 15 days following inoculation as described previously (4). Consistent with our earlier report (9), NL4-3 (X4) severely depleted these cultures of CD4 ϩ T cells, while the paired virus 49-5 (R5) depleted these cells only mildly (Fig. 1A). Recombinant strain 134 (X4) also severely depleted these cells, while its paired strain, 126 (R5), which differs by a single amino acid within the ...

The purpose of this pilot study was to investigate the effects of the transfusion of one erythrocyte concentrate on the number of circulating red blood cell extracellular vesicles (RBC‐EVs) and their clearance time. Six, healthy volunteers donated their blood and were transfused with their RBC concentrate after 35–36 days of storage. One K2EDTA and one serum sample were collected before donation, at four timepoints after donation and at another six timepoints after transfusion. RBC‐EVs were analyzed on a Cytek Aurora flow cytometer. A highly significant increase (p < 0.001) of RBC‐EVs from an average of 60.1 ± 19.8 (103/μL) at baseline to 179.3 ± 84.7 (103/μL) in the first 1–3 h after transfusion could be observed. Individual differences in the response to transfusion became apparent with one volunteer showing no increase and another an increased concentration at one timepoint after donation due to an influenza infection. We concluded that in an individualized passport approach, increased RBC‐EVs might be considered as additional evidence when interpreting suspicious Athletes Biological Passport (ABPs) but for this additional research related to sample collection and transport processes as well as method development and harmonization would be necessary.