Scientists from Japan developed a revolutionary artificial skin that can grow hair and perspire. This skin was grown in a laboratory by bioengineers from the RIKEN Center for Developmental Biology (CDB).

The researchers, led by Takashi Tsuji, used stem cells from mice gums and implanted it to a living mice while suppressing its immune system. Using that process, the scientists were able to produce a complex skin tissue that formed muscle and nerve fibers.

The bioengineers used the concept of organogenesis to develop the lab-grown skin. Taken into consideration are existing practices of regenerative therapy that use stem cell transplantations to repair damaged tissues and organs.

Previous studies, however, were not able to develop tissue replacements that have hair follicles because it is only present in embryonic organogenesis. For this reason, the bioengineers used embryonic stem (ES) cells and induced pluripotent stem (iPS) cells to develop the skin.

ES and iPS cells are ideal for their study because these cells can be programmed into differentiating as specific somatic cell lineages that can replicate embryogenic patterns and positions. Since they are still undifferentiated, they can still be induced to differentiate into any type of body cell.

For the study, a bioengineered 3D integumentary organ system (IOS) using several batches of iPS cells, including the appendage organs like sebaceous glands and hair follicles were used. The process involved collected gingival cells from mice to develop into an in vivo transplantation model to make it an embryoid body, which is a recreation of an embryo in a body, using Wnt10b signaling. The researchers also recreated the skin's chemical environment to encourage tissue growth.

Once the tissues matured and differentiated, they were transplanted onto the skin of a live and nude mouse. The transplanted skin developed normally with its muscle nerve and fibers connecting with the surrounding fibers and muscles allowing hair growth.

Although successful in transplanting a functional skin, the study has several limitations. It can connect to nerve fibers, but it cannot make new ones - a concern for patients with severe nerve damage. Additionally, the transplanted skin does not complement the existing skin. For instance, black hair can grow out from the new skin of a white-haired mouse.

Still, this study is revolutionary in treating patients who need skin transplant, particularly burn patients. Tsuji believes that their study opens possibilities in organ transplantation. He also said that their study can be used as an alternative for animal testing in drug developments.

"With this new technique, we have successfully grown skin that replicates the function of normal tissue," Tsuji said. "We are coming ever closer to the dream of being able to recreate actual organs in the lab for transplantation."

John McGRath, a molecular dermatology professor from King's College London is hopeful that the study would encourage more researchers to complement the findings.

"There will be lots of benefits for immediate use, as well as for translational science," McGrath said.

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