The current frontiers in oncology are at the nano-scale. Within this nanoworld, new bio-objects are being discovered and others are better characterized or revisited (e.g.: exosomes). Discovered in the early 80’s, exosomes are nanovesicles of endocytic origin that are released into the extracellular environment. The growing interest for exosomes in biology stems from the fact that these vesicles: (i) are ubiquitous (e.g. found in plants, in eukaryotic cells), (ii) contain a variety of molecules including signal peptides, mRNA, microRNA and lipids; (iii) are involved in local and systemic cell communication (exosomes bind to cells through receptor-ligand interactions, they can also pass the blood-brain barrier and through the placenta); (iv) are produced by many cells including: normal cells, dendritic cells, B cells, T cells, mast cells, epithelial cells, and tumour cells, (v) can be detected in body fluids like blood and urine.

In oncology, circulating tumor-derived exosomes have been shown to play a role in antigen presentation, in the development of tolerance and are emerging as mediators of tumorigenesis (in mouse and in human). Indeed, exosomes strongly affect the immune system by inhibiting the activity of T-cells, killer cells as well as the differentiation of precursors to mature antigen-presenting cells. They also increase the number and/or activity of immune suppressor cells such as myeloid-derived suppressor cells and T-regulatory cells. Exosomes may play a role in the crosstalk between the primary tumor and bone marrow-derived cells. Melanoma-derived exosomes from mice and humans were shown to promote metastatic niche formation through the upregulation of the MET oncoprotein. Recent data indicate that qualitative differences in exosomes content can mediate metastatic potential and organotropism. Exosomes seem also involved in the development and progression of cancers and may be used as biomarkers for cancer detection or tumor staging. For instance, in glioblastoma, although seldom circulating tumor cells are released, large quantities of vesicles can be detected within blood samples of patients. New labs-on-chip are being designed including a micro nuclear resonance devices. Finally, exosomes represent promising tools for the development of new vaccines or new drug delivery systems as they can encapsulate several types of molecules.

Therefore, in this early phase of great excitement several issues including extraction protocols, assays, characterization, quantification need to be addressed and standardized. A more homogeneous practice will obviously enable us to better characterize the several functions exosomes play in tumor biology.

Thus, this Research Topic intends to deal with some of the major issues, namely:

o characterization, quantification and regulation including:

protocols (e.g.: comparison of existing isolation protocols, derivation of improved ones),
current (e.g.: electron microscopy) or new biosensing schemes, limiting steps for their implementation in the clinic,
Composition (e.g :Proteins, mRNAs, miRNAs and lipids), distribution profiles of size and/or concentration,
regulation of production/composition/secretion and/or signal transduction in cancer vs. normal cells and tissues,
computer models (e.g.: systems biology approach),

o clinical evidences :

biomarkers: association with tumorigenesis, tumor progression and/or metastasis (prognostic or predictive)
clinical tool: approaches that mimic exosomes for imaging or treatment purposes (delivery of drugs, vaccination)

Manuscript submission:

Contributions addressing at least one of the above items will be considered for peer-reviewing. The types of suitable manuscripts are: research paper, review, comment and perspective (publishing fees are associated to certain article types, please check ).

Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.