For severe burn victims and others in need of skin transplants, current treatments using artificial skin grafts made from sheets of lab-grown skin cells aren’t ideal because they lack the complex structures needed to fully restore many of the skin’s critical functions.
For example, artificial skin doesn’t contain oil-producing sebaceous glands and forces burn victims to relentlessly apply oil to their skin grafts in order to prevent them from drying out and losing their natural cushioning and waterproof properties. Without the replacement of sweat glands and hair follicles within the skin tissue, the graft regions don’t adequately regulate body temperature. And the sense of touch is often lost as disrupted nerve fibers aren’t reconnected to transplanted skin.
The lack of a genuine skin replacement has emotional consequences too since skin grafts often don’t match up with surrounding skin and leaves victims disfigured. So, while current treatments help, the field is busily looking for new and better solutions.
New skin in the game
As reported in the latest issue of Science Advances, a research team from the RIKEN Center for Developmental Biology in Japan has taken a major step in the right direction by generating a fully functional 3D skin organ system in mice using stem cells.
The team accomplished this feat by first collecting gum cells from the mouth of the mouse and reprogramming them into induced pluripotent stem cells (iPS) which can specialize into any cell type of the body. After a few days in a petri dish, the iPS cells formed into embryoid bodies, clumps of cells that contain a random mix of cell types that would be seen in a developing embryo, including those that give rise to skin. Then, using a novel transplantation method, a cluster of several embryoid bodies were encased together in a gel and then transplanted into mice where they could grow for later testing.
Skin that sweats and grows hair
The embryoid body clusters were allowed to further develop in the mice for a month. The transplants were then taken out and their cellular structure and gene activity were analyzed. The results confirmed the formation of a complex, three-dimensional skin organ system complete with all three skin layers as well as hair follicles, sweat glands, oil-producing sebaceous glands and fat tissue.
In follow up experiments, small pieces of this tissue were transplanted into the skin of another set of mice. After 14 days, the researchers observed new hair growth from the follicles of the transplanted tissue. They also showed that the hair follicles had made the necessary connections to muscle tissue and nerve fibers of the host mice.
Translating this method for humans is years away but this data provides an important step toward a new generation of regenerative skin grafts that are fully functional as a complex organ system and not as just a two dimensional sheet of skin cells.
As study leader Takashi Tsuji mentions in a press release, skin transplants are not the only potential application of their technique:
“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.”
And with the restoration of functional hair follicles, maybe my fellow bald brethren could one day get back a full set of hair.