Fully functioning skin, which contains sweat glands and hair follicles, has been grown in a lab for the first time giving new hope for the treatment of hair loss.
Currently there are few treatments for many types of hair loss, oralopecia, which occurs when hair follicles are destroyed in the skin.
Although scientists have previously created the outer layer of skin in a lab – the epidermis – they have never managed to create the full organ which includes a layer of fatty tissue, and the dermis, where hair follicles and sweat glands are formed.
Now a team in Japan has shown it is possible to grow all three layers from stem cells, which they have successfully transplanted onto a mouse. Crucially the animals were able to grow hair, and sweat through the new skin and the organ bonded well with the skin that was already present and started to create new tissue.
“Up until now, artificial skin development has been hampered by the fact that the skin lacked the important organs, such as hair follicles and glands, which allow the skin to play its important role in regulation,” said lead researcher Dr Takashi Tsuji of the Riken Centre for Developmental Biology in Kobe.
“With this new technique, we have successfully grown skin that replicates the function of normal tissue.
“We are coming ever closer to the dream of being able to recreate actual organs in the lab for transplantation, and also believe that tissue grown through this method could be used as an alternative to animal testing of chemicals.
“Our study contributes to the development of bioengineering technologies that will enable future regenerative therapies for patients with burns, scars, and alopecia.”
Currently people with hair loss can have transplants from other parts of the body which still have follicles, but that would not be necessary with the new procedure. Only stem cells would be needed to kick-start the new skin growth.
Although the initial experiments were carried out in mice, scientists are hopeful the technique would work when transplanted into humans. As well as treating hair loss it could offer a far better prognosis for burns victims.
Many burns victims cannot grow hair back on their skin or scalp after injury because scar tissue does not have sweat glands or hair follicles.
Skin plays an important role in regulating body temperature, acting as the body’s thermostat. When temperatures rise, sweat glands activate to cool the body down and when temperatures are lower, blood vessels in the skin tighten and limit the amount of hot blood that can reach the skin, preventing heat loss.
Pores also become smaller when exposed to colder temperatures in order to retain heat.
Although current methods of growing a sheet of the epidermis in lab have helped restore some functions, the new technique would completely restore the damaged area.
“For regenerative therapy in patients with burns, a cultured sheet is useful for the replacement of skin physiological functions, such as the protection of deeper tissues, waterproofing, and thermoregulation,” wrote first author Ryoji Takagi of the Tokyo University of Science in the journal Science Advances.
“However, it is well recognized that current therapies using cultured tissues suffer from critical issues, including aesthetics and the inability to excrete sweat and lipids from exocrine organs
“It is expected that bioengineered (skin) can overcome these issues.”
The researchers took cells from mouse gums and used chemicals to transform them into stem cells which were then turned into an ‘embroyid body’ – a clump of cells which resembles a developing embryo. They were then transplanted into another mouse and within just a few days they started to turn into skin tissue.
Scientists then removed the new skin and implanted it into the original mice. The tissues formed proper connections with other organ systems such as nerves and muscle fibers without any rejection problems. The new skin was made fluorescent so it could be distinguished from the original layer.
The skin is the largest organ in the human body, and covers around two metres square, accounting for 15 per cent of body weight.