Discovery of Lactoferrin as a Stimulant for hADSC-Derived EV Secretion and Proof of Enhancement of Resulting EVs through Skin Model

Extracellular vesicles (EVs) are secreted from hADSCs in low concentrations, which makes it difficult to utilize them for the development of therapeutic products. To overcome the problem associated with low concentration, we proposed human lactoferrin (hLF) as a stimulant for the secretion of hADSC-derived EVs. hLF has been reported to upregulate intracellular Ca(2+), which is known to be capable of increasing EV secretion. We cultured hADSCs in hLF-supplemented media and analyzed the changes in intracellular Ca(2+) concentration. The characteristics of hADSC-derived EVs secreted by hLF stimulation were analyzed through their number, membrane protein markers, and the presence of hLFs to EVs. The function of hADSC-derived EVs was investigated through their effects on dermal fibroblasts. We found that hLF helped hADSCs effectively uptake Ca(2+), resulting in an increase of EVs secretion by more than a factor of 4. The resulting EVs had enhanced proliferation and collagen synthesis effect on dermal fibroblasts when compared to the same number of hADSC-derived EVs secreted without hLF stimulation. The enhanced secretion of hADSC-derived EVs increased collagen synthesis through enhanced epidermal penetration, which resulted from increased EV numbers. In summary, we propose hLF to be a useful stimulant in increasing the secretion rate of hADSC-derived EVs.