Human hair regeneration using organoids and hair-on-chip technologies

The hair follicle is a complex, dynamic mini organ that plays various important roles in facilitating the function of human skin. As human hair follicles do not naturally form after birth, there is a demand for methods to restore hair follicles in conditions involving permanent hair loss, such as scarring alopecia. However, robust therapeutics to regenerate hair follicles in humans have yet to be identified. Recent advances in the field of regenerative medicine show promise for human hair restoration. Regenerative medicine aims to restore lost tissues, such as hair follicles, by generating bioartificial substitutes. A myriad of biomaterials, scaffolds, and cell signalling modulators have been tested for hair regeneration. This includes strategies such as transplanting hair progenitor populations into skin to induce hair follicle neogenesis. Advanced manufacturing technologies such as 3D printing have also been employed to create bioprinted skin constructs with hair follicles, recapitulating hair-bearing human skin in vitro. Hair-on-a-chip models are also in development, which employ microfluidics and biomaterials to mimic the hair follicle microenvironment. Hair restoration has also been attempted through immunomodulatory methods, such as by employing Janus kinase inhibitors and mesenchymal stem cells for immunosuppression. Finally, human induced pluripotent stem cell-derived skin organoids have been established as a method to generate hair in vitro, creating various potential avenues for hair regenerative therapeutics. This Perspective reviews regenerative approaches to hair restoration, and emphasises the emerging role of engineered in vitro platforms in modelling human hair growth and enabling translational discovery.