A cure for baldness is on the horizon after scientists grew hair on mice – using human stem cells.
The breakthrough could lead to an unlimited supply of locks for millions who are follicly-challenged.
Currently, transplanting hair follicles from one part of the head to the other is the only option for male-pattern baldness.
It also offers hope of new treatments for the skin disease alopecia that causes hair to fall out – as well as burns victims.
Experts say the therapy, reported in British journal Nature, effectively “cured baldness” – since the cells were 100 percent human.
The US team created tiny skin buds, or ‘organoids’, in a petri dish from the pluripotent stem cells that can turn into any type of tissue.
When the “remarkably complete” skin was implanted onto the backs of immuno-compromised bald mice, hair loss was reversed.
Human style strands 2 to 5 millimetres in length sprouted on more than half (55%) of the grafts. They are the closest match to natural hair ever created.
Corresponding author Professor Karl Koehler, a plastic surgeon at Harvard Medical School in Boston, said: “This shows the organoids are capable of integrating with the mouse epidermis and forming human hair-bearing skin.”
It expressed genes characteristic of the chin, cheek, ear and scalp – suggesting it will work for hair transplants.
The buds were incubated in a cocktail of growth factors and other chemicals for four to five months.
This gave rise to both the upper and lower layers of skin – known as the epidermis and dermis.
Follicles with specific glands that lubricate hair with an oily substance called sebum also appeared – along with interwoven nerves, muscles and fat.
Skin is the most difficult organ in the body to mimic because of its complex structures and texture.
Prof Koehler said: “The skin is a multil-ayered organ, equipped with appendages such as follicles and glands that is critical for regulating body temperature and the retention of bodily fluids.”
These help protect the body against illness and injury as well as controlling the sensation of touch and pain.
Prof Koehler said: “Reconstructing appendage-bearing skin in cultures and in bio-engineered grafts is a challenge that has yet to be met.
“Here we report an organoid culture system that generates complex skin from human pluripotent stem cells.
“Direct comparison to foetal specimens suggest the skin organoids are equivalent to the facial skin of humans in the second trimester of development.
The skin buds could also lead to the development of better drugs for diseases – including cancer.
Prof Koehler said: “Our study establishes a model for investigating the cellular dynamics of developing human skin and its appendages – including sweat glands.
“A range of genetic skin disorders and cancers could be modelled with skin organoids
to accelerate drug discovery.
“Moreover, they could be used to reconstitute appendage-bearing skin in patients with skin burns or wounds.”
Dermatologists Dr Leo Wang and Dr George Cotsarelis, who were not involved in the study, described it as a “major step towards a cure for baldness.”
They said Jay Leno, former host of The Tonight Show in the US, once joked scientists had “cured baldness – at least in mice.”
Dr Wang and Dr Cotsarelis, of Pennsylvania University, said: “Sixteen years on, the current host will have the opportunity to mention that scientists have ‘cured’ baldness in humans.
“This achievement places us closer to generating a limitless supply of hair follicles that can be transplanted to the scalps of people who have thinning or no hair.
“Moreover, if the approach reaches the clinic, individuals who have wounds, scars and genetic skin diseases will have access to revolutionary treatments.”
They added: “The work holds great promise of clinical translation – we are confident that research will eventually see this promise realised.”138208672551
Last year another US team grew hair using a combination of cells from mice and humans.
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