Posted on 5 June 2020
Regenerative medicine using skin tissue is nothing new. For over three decades, it has been possible to isolate sheets of keratinocytes (the cells that make up 90% of the skin’s outer layer) from one part of the body and transplant them to another. This was a revolutionary procedure, allowing previously fatal burns or trauma to be treated.
However, the skin is a more complex tissue than it might seem, composed of multiple layers containing hair follicles, pigment-producing cells (melanocytes), sweat glands, nerves, muscle, fat and immune cells. The ideal skin graft would perfectly mimic normal skin by including all of these components. Now, research published in Nature has brought us closer to such a graft, by generating entire hair follicles from cultured stem cells.
Researchers sequentially added various growth factors to the cell culture to encourage the formation of skin organoids – lab-grown tissues that mimic developing skin. After 70+ days, hair follicles began to form, complete with sebaceous glands, nerves and their receptors, muscles and fat. Most hairs were also pigmented by melanocytes.
The researchers also showed that these follicles can produce hair when grafted onto mice. The organoids expressed genes characteristic of cells from the chin, cheek and ear, but it may be possible to produce skin cells with the characteristics of different body sites by altering the culture conditions. The technique could then be used not only to treat wounds and skin disorders, but also to generate scalp skin in order to reverse baldness.
There are still hurdles to be overcome before this therapy becomes clinically available. For example, it took 140 days before the organoids were ready to be engrafted, meaning that the protocol would have to be greatly accelerated for it to be useful in treating burns/trauma.
Hair-bearing human skin generated entirely from pluripotent stem cells: https://doi.org/10.1038/s41586-020-2352-3
Regenerative medicine could pave the way to treating baldness: https://www.nature.com/articles/d41586-020-01568-2
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