Novel biomaterial-based hair regrowth strategies: drug delivery systems and tissue engineering

Functional reconstruction of hair follicles is limited by microenvironmental dysregulation and impaired epithelial-mesenchymal interactions during alopecia. Conventional pharmacological interventions are limited by the stratum corneum barrier, which may reduce local bioavailability and potential systemic side effects. To overcome these barriers, biomaterial-based strategies have been developed to target and restore the hair follicle niche. Delivery systems, including hydrogels, microneedles, and micro/nanocarriers, can penetrate dermal tissues to enable the spatiotemporally controlled release of bioactive agents. This localized delivery modulates the pathological microenvironment by attenuating inflammation, reducing oxidative stress, and regulating stem cell behavior. Furthermore, engineering intact hair follicles requires biomimetic spatial architectures. Biofabrication techniques, such as three-dimensional bioprinting, microfluidic systems, and cellular self-assembly, allow the defined spatial arrangement of distinct cell populations to generate hair follicle organoids. This review summarizes recent advances in biomaterial-assisted hair regeneration and highlights the transition from traditional drug administration to targeted niche regulation, aiming to inform the design of next-generation biomaterials in hair regeneration therapies.