Julien is a dermatology biologist who conducted his thesis and postdoctoral research at Saint-Louis Hospital, Paris, focusing on wound healing and skin pathologies. After early work in cellular and tissue imaging, he joined L’Oréal, where he led applied research programmes for two decades, ultimately serving as Scientific Director for Skin Care. Since 2025, he has been at Timeline, shaping strategy to harness cellular longevity for breakthrough anti-ageing innovations.