Edible plants have been widely used in traditional therapeutics because of the biological activities of their natural ingredients, including anticancer, antioxidant, and anti-inflammatory properties. Plant sap contains such medicinal substances and their secondary metabolites provide unique chemical structures that contribute to their therapeutic efficacy. Plant extracts are known to contain a variety of extracellular vesicles (EVs) but the effects of such EVs on various cancers have not been investigated. Here, we extracted EVs from four plants—Dendropanax morbifera, Pinus densiflora, Thuja occidentalis, and Chamaecyparis obtusa—that are known to have cytotoxic effects. We evaluated the cytotoxic effects of these EVs by assessing their ability to selectively reduce the viability of various tumor cell types compared with normal cells and low metastatic cells. EVs from D. morbifera and P. densiflora sap showed strong cytotoxic effects on tumor cells, whereas those from T. occidentalis and C. obtusa had no significant effect on any tumor cell types. We also identified synergistic effect of EVs from D. morbifera and P. densiflora saps on breast and skin tumor cells and established optimized treatment concentrations. Our findings suggest these EVs from plant sap as new candidates for cancer treatment.

Size-based filtration techniques have been developed for high-throughput isolation of extracellular vesicles (EVs). Conventional direct filtration systems have limitations in that large particles generally not only block the pores of the membrane but also damage the particles because of the high fluid pressure. Here, we propose a cyclic tangential flow filtration (TFF) system that includes two membranes with pore sizes of 200 and 30 nm, connected to a peristaltic pump that feeds the stream flowing to the membrane for continuous circulation. The cyclic TFF system is better able to isolate the specific 30–200 nm size range in one step through dual cyclic filtration compared with direct filtration (DF) and single cyclic TFF (scTFF). We further introduced a buffer-exchange process to the dcTFF system after filtration to remove contaminants for more efficient purification. As a result of comparative evaluation of dcTFF and ExoQuick, EVs isolated by dcTFF had more abundant exosome markers and active EVs. The cyclic TFF system not only has great potential to separate EVs with high selectivity and separation efficiency in small volumes of samples but can also be used in clinical applications, including medical diagnostic procedures.

Plant-derived extracellular vesicles (EVs) are capable of efficiency delivering mRNAs, miRNAs, bioactive lipids, and proteins to mammalian cells. Plant-derived EVs critically contribute to the ability of plants to defend against pathogen attacks at the plant cell surface. They also represent a novel candidate natural substance that shows potential to be developed for food, cosmetic, and pharmaceutical products. However, although plant-derived EVs are acknowledged as having potential for various industrial applications, little is known about how their stability is affected by storage conditions. In this study, we evaluated the stability of Dendropanax morbifera leaf-derived extracellular vesicles (LEVs) alone or combined with the preservatives, 1,3-butylene glycol (to yield LEVs-1,3-BG) or TMO (LEVs-TMO). We stored these formulations at −20, 4, 25, and 45 °C for up to 4 weeks, and compared the stability of fresh and stored LEVs. We also assessed the effect of freeze-thawing cycles on the quantity and morphology of the LEVs. We found that different storage temperatures and number of freeze-thawing cycles altered the stability, size distribution, protein content, surface charge, and cellular uptake of LEVs compared to those of freshly isolated LEVs. LEVs-TMO showed higher stability when stored at 4 °C, compared to LEVs and LEVs-1,3-BG. Our study provides comprehensive information on how storage conditions affect LEVs and suggests that the potential industrial applications of plant-derived EVs may be broadened by the use of preservatives.

Cancer-associated fibroblasts (CAFs) in the cancer microenvironment play an essential role in metastasis. Differentiation of endothelial cells into CAFs is induced by cancer cell-derived exosomes secreted from cancer cells that transfer molecular signals to surrounding cells. Differentiated CAFs facilitate migration of cancer cells to different regions through promoting extracellular matrix (ECM) modifications. However, in vitro models in which endothelial cells exposed to cancer cell-derived exosomes secreted from various cancer cell types differentiate into CAFs or a microenvironmentally controlled model for investigating cancer cell invasion by CAFs have not yet been studied. In this study, we propose a three-dimensional in vitro cancer cell invasion model for real-time monitoring of the process of forming a cancer invasion site through CAFs induced by exosomes isolated from three types of cancer cell lines. The invasiveness of cancer cells with CAFs induced by cancer cell-derived exosomes (eCAFs) was significantly higher than that of CAFs induced by cancer cells (cCAFs) through physiological and genetic manner. In addition, different genetic tendencies of the invasion process were observed in the process of invading cancer cells according to CAFs. Our 3D microfluidic platform helps to identify specific interactions among multiple factors within the cancer microenvironment and provides a model for cancer drug development.