Background: Exosomes are extracellular vesicles involved in intercellular communication. The objectives were to characterize bovine milk exosomes (BME) and determine its effect on RAW 264.7 macrophages.
Methods: BME were isolated using differential centrifugation and characterized by particle size and the presence of exosomal markers Alix, TSG101, and CD81. The effect of in vitro digestion and different pH on the stability of BME was investigated. The biological activity of BME in RAW 264.7 macrophages was conducted by assessing proliferation and cell cycle. Moreover, the protective effect of exosomes on cisplatin-induced cytotoxicity was evaluated.
Results: BME have an average particle size of 106.8 ± 3.4 nm and expressed Alix, TSG101, and CD81. TSG101 was detected after digestion and exposure to different pH values. Cell-cycle analysis showed that BME reduced the percentage of apoptotic cells while arresting the cells in G2/M phase accompanied by differential expression of proliferation markers p53, p21, cyclin D1, and β-catenin. Exosomes protected macrophages against cisplatin-induced cytotoxicity.
Conclusion: Our results showed for the first time the effect of BME on the proliferation of RAW 264.7 macrophages and its protective effect against chemotherapeutic drug-induced cytotoxicity. Potential effect of BME on immune system must be studied.
Keywords: Bovine milk; RAW 264.7 macrophages; cell cycle; exosomes; proliferation.