Exosome-like vesicles in Apis mellifera bee pollen, honey and royal jelly contribute to their antibacterial and pro-regenerative activity

Microvesicles have become key players in cellular communication. Since glandular secretions present a rich source of active exosomes, we hypothesized that exosome-like vesicles are present in Apis mellifera hypopharyngeal gland secretomal products (honey, royal jelly and bee pollen), and participate in their known antibacterial and pro-regenerative effects. We developed an isolation protocol based on serial- and ultracentrifugation steps and demonstrated the presence of protein-containing exosome-like vesicles in all three bee-derived products. Assessing their antibacterial properties, we found that exosome-like vesicles had bacteriostatic, bactericidal and biofilm-inhibiting effects on Staphylococcus aureus. Furthermore, we could demonstrate that mesenchymal stem cells (MSCs) internalize bee-derived exosome-like vesicles and that these vesicles influence their migration potential. In an in vitro wound healing assay, honey and royal jelly exosome-like vesicles increased migration of human MSC, demonstrating their interkingdom activity. Summarizing, we have discovered exosome-like vesicles as a new, active compound in bee pollen, honey and royal jelly.