Exosomes are vesicles of endocytic origin released by many cells. These vesicles can mediate communication between cells, facilitating processes such as antigen presentation. Here, we show that exosomes from a mouse and a human mast cell line (MC/9 and HMC-1, respectively), as well as primary bone marrow-derived mouse mast cells, contain RNA. Microarray assessments revealed the presence of mRNA from approximately 1300 genes, many of which are not present in the cytoplasm of the donor cell. In vitro translation proved that the exosome mRNAs were functional. Quality control RNA analysis of total RNA derived from exosomes also revealed presence of small RNAs, including microRNAs. The RNA from mast cell exosomes is transferable to other mouse and human mast cells. After transfer of mouse exosomal RNA to human mast cells, new mouse proteins were found in the recipient cells, indicating that transferred exosomal mRNA can be translated after entering another cell. In summary, we show that exosomes contain both mRNA and microRNA, which can be delivered to another cell, and can be functional in this new location. We propose that this RNA is called "exosomal shuttle RNA" (esRNA).

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Exosome-mediated transfer of mRNAs and microRNAs is a novel mechanism of genetic exchange between cells

Cells release into the extracellular environment diverse types of membrane vesicles of endosomal and plasma membrane origin called exosomes and microvesicles, respectively. These extracellular vesicles (EVs) represent an important mode of intercellular communication by serving as vehicles for transfer between cells of membrane and cytosolic proteins, lipids, and RNA. Deficiencies in our knowledge of the molecular mechanisms for EV formation and lack of methods to interfere with the packaging of cargo or with vesicle release, however, still hamper identification of their physiological relevance in vivo. In this review, we focus on the characterization of EVs and on currently proposed mechanisms for their formation, targeting, and function.

https://rupress.org/jcb/article-pdf/200/4/373/1262520/jcb_201211138.pdf

Extracellular vesicles: exosomes, microvesicles, and friends.

Exosomes are small membrane vesicles found in cell culture supernatants and in different biological fluids. Exosomes form in a particular population of endosomes, called multivesicular bodies (MVBs), by inward budding into the lumen of the compartment. Upon fusion of MVBs with the plasma membrane, these internal vesicles are secreted. Exosomes possess a defined set of membrane and cytosolic proteins. The physiological function of exosomes is still a matter of debate, but increasing results in various experimental systems suggest their involvement in multiple biological processes. Because both cell-culture supernatants and biological fluids contain different types of lipid membranes, it is critical to perform high-quality exosome purification. This unit describes different approaches for exosome purification from various sources, and discusses methods to evaluate the purity and homogeneity of the purified exosome preparations.

/pdf/isolation-and-characterization-of-exosomes-from-cell-culture-4k118gm22m.pdf

Isolation and Characterization of Exosomes from Cell Culture Supernatants and Biological Fluids

Extracellular vesicles are a heterogeneous group of cell-derived membranous structures comprising exosomes and microvesicles, which originate from the endosomal system or which are shed from the plasma membrane, respectively They are present in biological fluids and are involved in multiple physiological and pathological processes Extracellular vesicles are now considered as an additional mechanism for intercellular communication, allowing cells to exchange proteins, lipids and genetic material Knowledge of the cellular processes that govern extracellular vesicle biology is essential to shed light on the physiological and pathological functions of these vesicles as well as on clinical applications involving their use and/or analysis However, in this expanding field, much remains unknown regarding the origin, biogenesis, secretion, targeting and fate of these vesicles

/pdf/shedding-light-on-the-cell-biology-of-extracellular-vesicles-52ri6w7hp6.pdf

Shedding light on the cell biology of extracellular vesicles.

In the 1980s, exosomes were described as vesicles of endosomal origin secreted from reticulocytes. Interest increased around these extracellular vesicles, as they appeared to participate in several cellular processes. Exosomes bear proteins, lipids, and RNAs, mediating intercellular communication between different cell types in the body, and thus affecting normal and pathological conditions. Only recently, scientists acknowledged the difficulty of separating exosomes from other types of extracellular vesicles, which precludes a clear attribution of a particular function to the different types of secreted vesicles. To shed light into this complex but expanding field of science, this review focuses on the definition of exosomes and other secreted extracellular vesicles. Their biogenesis, their secretion, and their subsequent fate are discussed, as their functions rely on these important processes.

/pdf/biogenesis-secretion-and-intercellular-interactions-of-4pskmvujl3.pdf

Biogenesis, Secretion, and Intercellular Interactions of Exosomes and Other Extracellular Vesicles

The More, the Merrier: DC3s Join the Human Dendritic Cell Family.

Recent advances towards deciphering human dendritic cell development.

https://hal.archives-ouvertes.fr/hal-03090929/document

Surface LSP-1 Is a Phenotypic Marker Distinguishing Human Classical versus Monocyte-Derived Dendritic Cells.

naive T cell priming ICAM-1 on exosomes from mature dendritic cells is critical for efficient

We thank Burgdorf et al. for suggesting potential explanations for the few discrepancies between our studies (1, 2).

Our collagenase treatment did not prevent us from detecting the mannose receptor (MR) on splenic macrophages and inflammatory dendritic cells (DC), or from confirming a role for MR in OVA uptake by the latter (1). We have analyzed MR expression on cells purified with or without collagenase digestion with identical results: macrophages express MR, but steady-state DC do not (Fig. 1). Furthermore, OVA uptake was not affected by the use of collagenase (Fig. 1). Some commercial preparations of collagenase contain trypsin-like activity that might affect MR detection or OVA uptake; we used collagenase tested for the absence of this activity. Previous studies also failed to detect MR in steady-state DC (3, 4). These studies included in situ staining of tissue sections, which would … 

1To whom correspondence should be addressed. E-mail: villadangos{at}wehi.edu.au.

https://www.pnas.org/content/pnas/107/13/E50.full.pdf

Elodie Segura

Papers

The More, the Merrier: DC3s Join the Human Dendritic Cell Family.

Recent advances towards deciphering human dendritic cell development.

Surface LSP-1 Is a Phenotypic Marker Distinguishing Human Classical versus Monocyte-Derived Dendritic Cells.

naive T cell priming ICAM-1 on exosomes from mature dendritic cells is critical for efficient

Reply to Burgdorf et al.: The mannose receptor is not involved in antigen cross-presentation by steady-state dendritic cells