Stem cells: Making human skin in a dish

Skin organoids generated in a dish from human pluripotent stem cells can form multi-layered skin tissue with hair follicles, sebaceous glands and neural circuitry when cultured for 4–5 months. The findings, reported in Nature this week, could provide a tool for studying human skin development, with insights for disease modelling and reconstructive surgery.

Culture systems have long been used to study the development of human skin outside the body. However, the skin is a complex, multi-layered organ involved in diverse processes from temperature regulation and bodily fluid retention to the sensing of touch and pain. As such, reconstructing skin with its associated structures — such as hair follicles and sebaceous glands — has been a major biomedical challenge.

Karl Koehler and colleagues report an organoid culture system that can generate skin organoids from human pluripotent stem cells through careful optimization of growing conditions. After an incubation period of 4–5 months, the organoids had distinct epidermis and dermis layers, as well as hair follicles with sebaceous glands and interwoven nerve circuitry. When implanted onto the back skin of immunocompromised mice, 2–5 mm hairs sprouted on 55% of the grafts, showing that the organoids are capable of integrating with the mouse epidermis and forming human hair-bearing skin.

Several questions remain before this therapeutic approach can become a reality, write Leo Wang and George Cotsarelis in an accompanying News & Views article. Yet, they conclude: “The work holds great promise of clinical translation — we are confident that research will eventually see this promise realized.”