Skin equivalents are able to mimic key features of human skin and they can be used for a very broad range of applications, such as fundamental studies of skin biology, disease, and toxicological models, as well as an alternative for animal testing. The high end of their use is in therapy of wound healing and repigmentation and disorders that massively affect individual health as well as quality of life and pose considerable burden to health care systems worldwide. Tissue-engineered skin grafts often originate from invasively obtained cell material (i.e., biopsy). Hereby, an unmet need for noninvasively gained autologous biological starting material has been created. The hair follicle, entirely noninvasively available by plucking, harbors a heterogeneous cell pool, including stem cells with an immense differentiation capacity, hereby representing an attractive source of cells, especially for purposes of regenerative medicine. In this study, we engineered three-dimensional pigmented epidermal and dermoepidermal grafts using human keratinocytes and melanocytes from the outer root sheath of hair follicles combined with dermal fibroblasts. The grafts were generally anatomically correct and functional regarding stratification and formation of epidermal melanin units, as well as extracellular matrix deposition, exhibiting moderate differences to the skin anatomy and function, typical for the in vitro culture. Impact statement The study focuses on generation of tissue-engineered skin equivalents, in particular, as a possible treatment for nonhealing wounds and depigmentation disorders. We developed an in vitro-generated three-dimensional pigmented epidermal and dermoepidermal graft using keratinocytes and melanocytes from the outer root sheath of human hair follicle combined with dermal fibroblasts. The anatomically and functionally correct grafts showed stratification, epidermal melanin units, and extracellular matrix deposition. They present an in vitro base for an autologous, pigmented graft as well as for further personalized in vitro experimental models generated from a noninvasively obtained cell source, addressing the unmet needs of the currently available clinical treatments.
Keywords: ORS; keratinocytes; melanocytes; skin equivalents; tissue engineering.