Search

Background: Eukaryotic cells release vesicles of different sizes under both physiological and pathological conditions. On the basis of the respective biogenesis, extracellular vesicles are classified as apoptotic bodies, microvesicles, and exosomes. Among these, exosomes are considered tools for innovative therapeutic interventions, especially when engineered with effector molecules. The delivery functions of exosomes are favored by a number of typical features. These include their small size (i.e., 50-200 nm), the membrane composition tightly similar to that of producer cells, lack of toxicity, stability in serum as well as other biological fluids, and accession to virtually any organ and tissue including central nervous system. However, a number of unresolved questions still affects the possible use of exosomes in therapy. Among these are the exact identification of both in vitro and ex vivo produced vesicles, their large-scale production and purification, the uploading efficiency of therapeutic macromolecules, and the characterization of their pharmacokinetics. Objective: Here, we discuss two key aspects to be analyzed before considering exosomes as a tool of delivery for the desired therapeutic molecule, i.e., techniques of engineering, and their in vivo biodistribution/ pharmacokinetics. In addition, an innovative approach aimed at overcoming at least part of the obstacles towards a safe and efficient use of exosomes in therapy will be discussed. Conclusion: Several biologic features render exosomes an attractive tool for the delivery of therapeutic molecules. They will surely be a part of innovative therapeutic interventions as soon as few still unmet technical hindrances will be overcome.

Nef is an accessory protein expressed exclusively in primate lentiviruses. It is devoid of enzymatic activities while interacting with several cell proteins as an adaptor/scaffold protein. Intracellular functions of Nef largely account for many pathogenic effects observed in AIDS disease. Nef, despite lacking known secretory pathways, can be detected in plasma of HIV-1-infected patients at the concentration varing from 5 to 10 ng/ml. Remarkably, the levels of Nef in plasma of HIV patients do not correlate with viral load or number of CD4+ T lymphocytes, and persist during antiretroviral therapy. Here, we review literature data describing how Nef can be transmitted from HIV-1- infected cells to bystander ones, and the effects of extracellular Nef in different cell types. Overall, large part of experimental evidences supports the idea that extracellular Nef plays a relevant role in AIDS pathogenesis. Hence, efforts focused on the identification of Nef-inhibiting drugs would be of relevance to establish new therapeutic approaches supporting current antiretroviral therapies.