Exosomes are lipid bilayer membrane vesicles and are emerging as competent nanocarriers for drug delivery. The clinical translation of exosomes faces many challenges such as massive production, standard isolation, drug loading, stability and quality control. In recent years, artificial exosomes are emerging based on nanobiotechnology to overcome the limitations of natural exosomes. Major types of artificial exosomes include ‘nanovesicles (NVs)’, ‘exosome-mimetic (EM)’ and ‘hybrid exosomes (HEs)’, which are obtained by top-down, bottom-up and biohybrid strategies, respectively. Artificial exosomes are powerful alternatives to natural exosomes for drug delivery. Here, we outline recent advances in artificial exosomes through nanobiotechnology and discuss their strengths, limitations and future perspectives. The development of artificial exosomes holds great values for translational nanomedicine.

Extracellular vesicles (EVs) are nanovesicles involved in multiple biological functions. Small EVs (sEVs) are emerging as therapeutics and drug delivery systems for their contents, natural carrier properties, and nanoscale size. Despite various clinical application potentials, little is known about the effects of storage conditions on sEVs for functional analysis and therapeutic use. In this study, we evaluated the stability of sEVs stored at 4 °C, −20 °C, and −80 °C up to 28 days and compared them to fresh sEVs. Also, the effect of freeze-thawing circles on the quantity of sEVs was assessed. We found that different storage temperatures, along with shelf life, impact the stability of sEVs when compared to freshly isolated sEVs. Storage changes the size distribution, decreases quantity and contents, and impacts cellular uptake and biodistribution of sEVs. For functional studies, isolated sEVs are suggested to be analyzed freshly or stored at 4 °C or −20 °C for short-term preservation depending on study design; but −80 °C condition would be more preferable for long-term preservation of sEVs for therapeutic application.

Mesenchymal stem cells (MSCs) were known to have excellent properties in cell therapy. However, the risk of immune rejection associated with cell transplant therapy hampers its use. Extracellular vesicles secreted by MSCs derived from different sources that contain therapeutic molecules such as RNA and proteins, which is a novel strategy for cell-free therapy. Recently, researches show EVs from MSCs (MSC-EVs) of different sources have special functions and effects on different diseases. Here, we collected these researches and compared them to each other. In addition, their potential and possible application in clinical treatment are described.

In the past 40 years, the nanoparticle drug delivery system for tumor peptide vaccines has been widely studied which also reached a splendid result. Nanomaterial can enhance the targeting of vaccines, help vaccines enter the cells and trigger immune response by themselves. They also help in increasing cellular uptake, improving permeability and efficacy. Currently, several categories of nanopreparation, such as liposome, polymeric micelle, polymeric nanoparticle, gold nanoparticle and so on, are proved that they are appropriate for peptide vaccines. This review we discussed the possible mechanisms of nanomaterial's action on the regulation of immunological functions and several major applications of this advanced drug delivery system for tumor peptide vaccine.