Hair Follicles: Strategic Targets for Promoting Hair Growth

The hair follicle is much more than a simple anchor for the hair shaft: it is a complex micro-organism, richly vascularized, with a great capacity for absorption. This unique anatomical structure has emerged as a promising pathway for the targeted delivery of active substances, particularly for treating hair disorders. Owing to its funnel-shaped architecture and its associated sebaceous and eccrine glands, the follicle provides an extensive contact surface and direct access to the dermal layer. Numerous studies have highlighted its ability to enhance skin penetration and to support the sustained release of active compounds. In addition to its structural advantages, the hair follicle exhibits dynamic biological activity, including a cyclic growth pattern that can influence the permeability and receptivity of the follicular environment. This dynamic behavior opens new avenues for timed and localized drug delivery. Furthermore, innovative carrier systems, such as nanoparticles, microparticles, liposomes, solid lipid nanoparticles, and polymer-based vehicles have been developed to optimize transfollicular targeting and improve therapeutic efficacy while minimizing systemic exposure. This article reviews the morphological and physiological characteristics of the hair follicle, its role in transfollicular uptake, and recent advances in delivery technologies that enable safe, targeted, and efficient administration of active substances to the hair and scalp, for cosmetic and medical purposes. Keywords: Hair follicle, targeted delivery, carrier systems, transfollicular administration, hair disorders