S u m m a r y :
Scientists have grown skin with hairs in laboratory. The experiments are documented in the journal Cell Reports.
You can now grow hairy skin in laboratory! And no, it’s not meant as a weird beauty experiment. Rather, the brains behind the successful endeavour, researchers from Indiana University School of Medicine, mean to use their discovery to model disease with the aim of developing new therapies to treat skin disorders and cancers. The hairy skin comes from the cells of mice; it is the first evidence of hair follicles growing in stem cell cultures.
“The skin is a complex organ that has been difficult to fully recreate and maintain in culture for research purposes,” says lead author Karl Koehler. “Our study shows how to encourage hair development from lab grown mouse skin, which has been particularly troublesome for researchers to recreate in culture.”
It all started with an ear. The new study is based on previous findings of the same team. Together with his colleagues, Koehler concocted a way to use stem cells to grow inner ear cells: mouse stem cells were curled up into a 3D ball to which specific signalling molecules were added to trigger the cells to differentiate into inner ear tissue. This process created a byproduct: skin cells.
“In the developing embryo, the inner ear comes from the same layer of cells as the top layer of the skin, [the epidermis], so it was no surprise that skin and inner ear tissue formed in tandem,” Dr. Koehler said. “We were surprised to find that the bottom layer of the skin [the dermis] also develops.”
For the new research, the scientists made the epidermis and dermis cells into a spherical aggregation of cells known as a skin organoid. The cells making up the latter display an organisation that bears resemblance to normal skin, but inside-out, that is, the top skin layer looks towards the inside of the organoid.
Cultures of the skin organoids were made, resulting in more developed ones, similar to the evolution of skin in the embryo. Then, after 20 days, the scientists observed hair follicles sprouting from the skin organoids. Koehler commented that the follicle roots would come from the organoids in all directions.
Further research revealed that the timing of development and expression of key proteins was very similar to skin and hair development in mouse embryos. More investigation showed a greater specialisation among the cells.
“In addition to the major epidermal and dermal cell types we also found specialized cell types, such as melanocytes [pigment cells], Merkel cells [touch sensing cells], adipocytes [fat cells], sebaceous gland cells, and hair follicle stem cells in organoids,” Dr. Koehler said. “This is fascinating because it shows that if we derive the basic building blocks of skin together in culture, then these diverse cell types will self-assemble on their own.”
The authors say that their findings have the potential to open the door to new techniques for skin grafting involving hair follicles together with therapies for human diseases like alopecia, acne, and skin cancers. Moreover, this might decrease the dependence on experimental animals for research purposes.
“My hope is that by improving skin-in-a-dish models we can greatly diminish the sacrifice of experimental animals and ultimately help patients with skin-related issues live a better life,” says first author Lee.