The potential roles of vesicle-enclosed miRNAs in communication between macrophages and cancer cells in tumor microenvironment.

Functional microRNA (miRNA) molecules are transported in extracellular vesicles among tumor cells and cells of the immune system. Macrophages as integral components of tumor microenvironment are known as potential contributors to tumor growth and progression. We searched for studies which could provide a direct link between the particular miRNAs transported between cancer cells and macrophages and experimental evidence of subsequent alterations in biological functions of target cells. The validated targets of such microRNAs were found using miRWalk database. These targets were further subjected to analysis by DAVID (Database for Annotation, Visualization and Integrated Discovery) to find the most prominent cellular events that could be potentially regulated in macrophages by miRNAs originated from cancer cells and vice versa. We found that the 5 miRNAs (let-7b, miR-21, miR-29a, miR-222-3p, miR-451) derived from cancer cells may together regulate 2304 target genes in macrophages. The genes involved in regulation of apoptosis, regulation of gene expression and protein transport were significantly overrepresented in this set. Four of the five sets of target genes for these individual miRNAs overlap in MYC oncogene. MYC dependent transcriptional program is responsible for cell cycle entry and regulates the inflammatory response in macrophages.Both miRNAs for which the functional transports from macrophages to cancer cells were experimental proven (miR-223, miR-142-3p) target total 684 genes including some well-known tumor suppressors like TP53 or APC. Suppression of tumor suppressor genes by miRNAs derived from macrophages may eventually contribute to cancer cell proliferation.Due to the complexity of tumor microenvironment, the altered expression profiles of its components affected by miRNA uptake from extracellular vesicles could contribute to the outcome of carcinogenesis therefore the vesicular transport of miRNAs should be studied more extensively in this context.

The Quality Control of Mesenchymal Stromal Cells by in Vitro Testing of Their Immunomodulatory Effect on Allogeneic Lymphocytes.

Mesenchymal stromal cells (MSC) represent a promising treatment of graft-versus-host disease (GVHD) in patients after allogeneic haematopoietic stem cell transplantation. We performed co-cultivation experiments with non-specifically stimulated lymphocytes to characterize the immunosuppressive activity of MSC. MSC influenced expression of some activation antigens. CD25 expression was lower with MSC and reached 55.2 % vs. 84.9 % (CD4+, P = 0.0006) and 38.8 % vs. 86.6 % (CD8+, P = 0.0003) on day +4. Conversely, CD69 antigen expression remained higher with MSC (73.3 % vs. 56.8 %, P = 0.0009; 59.5 % vs. 49.7 %, ns) and its down-regulation along with the culture time was less pronounced. MSC reduced proliferation of the stimulated lymphocytes. The cell percentages detected in daughter generations were decreased (32.82 % vs. 10.68 % in generation 4, P = 0.0004 and 29.85 % vs. 10.09 % in generation 5, P = 0.0008), resulting in a lower proliferation index with MSC (1.84 vs. 3.65, P < 0.0001). The addition of MSC affected expression of some cytokines. Production of pro-inflammatory cytokines was decreased: IL-6 (19.5 vs. 16.3 MFI; P < 0.0001 in CD3+/CD4+ and 14.5 vs. 13.2 MFI; P = 0.0128 in CD3+/CD8+), IFN-γ (13.5 vs. 12.0 MFI; P = 0.0096 in CD3+/CD4+). Expression of anti-inflammatory IL-10 was only slightly increased after the addition of MSC (ns). The analysis confirmed the immunomodulatory activity of MSC. The functional tests have proved to be an important part of the quality control of the advanced therapy cellular product intended for GVHD treatment. Future research should focus on the interaction between MSC and the patient immune environment more closely.