Novel roles of bovine milk‐derived exosomes in skin antiaging.

Background: Exosomes are small vesicles released from cells and are found in various mammalian biological fluids, such as bovine milk, which has been employed in skincare for many years, apart from its dairy applications. In addition, exosomes have been recognized as vehicles for intercellular communication. Aims: In this study, we aimed to investigate the novel effects of bovine milk‐derived exosomes (MK‐Exo) on antiaging in human skin. Methods: Initially, MK‐Exo were co‐cultured with keratinocytes and fibroblasts; subsequent analysis involved qPCR and western blotting to assess induced gene expression. Subsequently, MK‐Exo were topically applied to the facial skin of 31 female volunteers twice daily for 28 days. The functions were evaluated after conducting safety assessments in vivo. Results: Purified MK‐Exo demonstrated the ability to be taken up directly by keratinocytes and fibroblasts in vitro, resulting in the upregulation of natural factors associated with skin moisturization, including filaggrin (FLG), aquaporin 3 (AQP3), and CD44 in keratinocytes, as well as hyaluronidase (HAS2) in fibroblasts. Concurrently, MK‐Exo promoted fibroblast cell migration and restored the expression of type I and III collagen (Col I and Col III) following exposure to ultraviolet radiation. Furthermore, phototoxicity, photoallergy, repeated skin irritation, skin allergy, and patch tests confirmed the safety of MK‐Exo for skin application. Finally, we elucidated the roles of MK‐Exo in preserving moisture and reducing wrinkles in humans. Conclusion: Our findings unveil the novel contributions of MK‐Exo to human skin aging, presenting a new avenue in the field of skincare. [ABSTRACT FROM AUTHOR]