Extracellular Vesicles: A Mechanism to Reverse Metastatic Behaviour as a New Approach to Cancer Therapy

Abstract

Extracellular vesicles EVs are membrane-bound particles shed from nearly all cell types into the extracellular environment. This collective term includes vesicles ranging in size from nm to μm in diameter. Various isolation techniques are used in different studies to separate EVs with no consensus protocol. EVs are released from cells under normal physiological conditions as well as in stressful and pathological conditions. In malignancies, they have been shown to be useful circulating markers for risk assessment, early diagnosis, monitoring of therapeutic effectiveness and prognosis. In addition, they appear to influence cell death and growth, angiogenesis, immune surveillance, extracellular matrix degradation and metastasis. In this respect, EVs have generated considerable interest for their potential use in cancer therapeutics. Since they appear to be responsible for transference of cellular components between cells and thereby transfer of functional characteristics of the donor to the recipient, two strategies for their role in cancer therapeutics may be envisaged. The first would be to prevent formation and/or shedding of EVs to prevent communication to or from cancer cells. The second would be to utilize them as carriers to deliver inhibitory/toxic components into cancer cells to destroy or neutralize them. In this review, we discuss the current state of research on characterization of EVs and highlight possible strategies for their use in cancer therapy.Keywords: cancer, microvesicles, EVs, exosomes, drug delivery © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. . IntroductionExtracellular vesicles EVs are membrane-bound particles shed into the extracellular environment by many types of cell under different circumstances ranging from normal physiological conditions to pathological conditions like cancer. There are several ways of classifying EVs, including size and mode of biogenesis. Some authors use the designation EVs interchangeably with other terms like exosomes and microvesicles MVs . This has led to some confusion and inconsistency as to the particles actually being studied. Therefore, we have included a section on the various isolation procedures to emphasise the importance of standardization. Indeed, in many studies, there is no or unconvincing characterization of preparations. In this chapter, we will use EVs as a broad term to encompass three categories exosomes, microvesicles and When first discovered, the release of EVs from cells was thought to be a mechanism for removal of waste and harmful substances from the cell. Nowadays, they are viewed as mediators of intercellular communication through the transfer of biologically active molecules from donor to recipient cells where they can modulate the phenotype and function of those recipient ce...