Ex vivo microvesicle formation after prolonged ischemia in renal transplantation

Macrophage microvesicles induce macrophage differentiation and miR-223 transfer

Microvesicles are small membrane-bound particles comprised of exosomes and various-sized extracellular vesicles. These are released by several cell types. Microvesicles have a variety of cellular functions from communication to mediating growth and differentiation. Microvesicles contain proteins and nucleic acids. Previously, we showed that plasma microvesicles contain microRNAs (miRNAs). Based on our previous report, the majority of peripheral blood microvesicles are derived from platelets, while mononuclear phagocytes, including macrophages, are the second most abundant population. Here, we characterized macrophage-derived microvesicles and explored their role in the differentiation of naive monocytes. We also identified the miRNA content of the macrophage-derived microvesicles. We found that RNA molecules contained in the macrophage-derived microvesicles were transported to target cells, including mono cytes, endothelial cells, epithelial cells, and fibroblasts. Furthermore, we found that miR-223 was transported to target cells and was functionally active. Based on our observations, we hypothesize that microvesicles bind to and activate target cells. Furthermore, we find that microvesicles induce the differentiation of macrophages. Thus, defining key components of this response may identify novel targets to regulate host defense and inflammation.

Microvesicles as novel biomarkers and therapeutic targets in transplantation medicine

Microvesicles (MVs) including exosomes are emerging new biomarkers and potential regulators of inflammation and immunological processes. Such particles contain proteins and genetic information including DNA and microRNAs that may be of importance for cell/cell communication. However, their role during and after organ transplantation and immunomodulatory effects is only in its beginning of understanding. We here, in brief, introduce generation and biological importance of MVs, describe their (patho)physiological roles and their potential use as future biomarkers and therapeutic agents in transplantation medicine. Circulating MVs may have a great potential to detect possible immune rejections and MV modulation may emerge as a therapeutic approach in organ rejection therapy.