"Bioprinting of Hair: How Far We Proceeded and What Needs to be Done"

Alopecia is a common dermatologic disorder with psychological and quality-of-life impact. Current options such as PRP, topical agents, microneedling or dermarollers, drugs, and transplantation, often provide only partial or short-term benefit and depend on existing follicles. 3D bioprinting is transforming regenerative trichology by positioning cells and "bioinks" to recreate hair-bearing skin. Advances include biomimetic dermal papilla spheroids, follicle organoids in engineered dermis, and bioprinted skin equivalents with nascent HF-like structures. Translation is limited by vascular and nerve integration and hair-cycle control. These priorities will enable robust clinical regeneration. This review recapitulates the recent advances at the interface of hair-follicle biology and 3D bioprinting, and delineates key bioengineering and cellular components underpinning folliculogenesis. Recent advancements have enabled the fabrication of biomimetic dermal papilla spheroids, the spatial integration of hair-follicle organoids within engineered dermal matrices, and the fabrication of bioprinted skin equivalents containing nascent HF-like structures, representing functional relevance for pharmacological evaluation and regenerative transplantation studies. Clinical translation of hair bioprinting remains impeded by the integration of functional vascular and neural networks, and recapitulating hair-cycle dynamics. This review outlines strategic priorities required to move the field from experimental proof of concept to scalable, clinically relevant hair regeneration using bio-prinking technology.