Bovine milk-derived exosomes for drug delivery

Abstract

Exosomes are biological nanovesicles that are involved in cell-cell communication via the functionally-active cargo (such as miRNA, mRNA, DNA and proteins). Because of their nanosize, exosomes are explored as nanodevices for the development of new therapeutic applications. However, bulk, safe and cost-effective production of exosomes is not available. Here, we show that bovine milk can serve as a scalable source of exosomes that can act as a carrier for chemotherapeutic/chemopreventive agents. Drug-loaded exosomes showed significantly higher efficacy compared to free drug in cell culture studies and against lung tumor xenografts in vivo. Moreover, tumor targeting ligands such as folate increased cancer-cell targeting of the exosomes resulting in enhanced tumor reduction. Milk exosomes exhibited cross-species tolerance with no adverse immune and inflammatory response. Thus, we show the versatility of milk exosomes with respect to the cargo it can carry and ability to achieve tumor targetability. This is the first report to identify a biocompatible and cost-effective means of exosomes to enhance oral bioavailability, improve efficacy and safety of drugs.

Biocompatibility of highly purified bovine milk‐derived extracellular vesicles

“…The yield of mEV was over 10 µg/mL-whey (Table 1). Compared with the previously reported C/UC method [11], our method yields 20-fold lower amounts of mEVs. Another report employing size-exclusion chromatography showed that the yield of mEVs from bovine milk is from 51 to 114 µg/mL [20].…”

“…Since majority of whey protein is casein (up to 80% of total whey protein), removal of casein is the key for obtaining pure mEV fraction. Although previous reports employed centrifugation to remove casein [11], it is difficult to separate casein from mEVs, since colloidal characteristics of casein micelles are similar to mEVs (diameter and density are 100 nm [23] and 1.08 g/mL [24], respectively, for casein micelles). Acid precipitation is frequently used to remove casein from whole milk, owing to the low pI of casein (pH 4.5 [25]).…”

“…It was suggested that orally administered mEVs and their cargo RNA can be adsorbed and go into the blood circulation of mice [16]. Furthermore, oral administration of mEV encapsulating anti-tumour agents can suppress tumour growth in the mouse xenograft model [11,18]. Taken together, orally and intravenously administered mEVs can deliver therapeutic molecules.…”

“…A conventional isolation method was performed according to the previous article [11]. Whole bovine milk was purchased from a local supermarket.…”

Therapeutic biomaterials based on extracellular vesicles: classification of bio‐engineering and mimetic preparation routes

“…The effects of solvents and drug release kinetics from loaded exosomes by dialysis have been studied [39,76]. …”