Researchers have successfully 3D-printed hair follicles in cultured human skin tissues, but potential applications for direct patient use won’t be seen for some time. Instead, the development could be used in drug testing, since hair follicles are an entry point for topical drugs and cosmetics.
Currently, initial safety testing of topically-applied drugs is done on engineered skin tissues that lack hair follicles.
Scientists at Rensselaer Polytechnic Institute 3D-printed the hair follicles and published their research in the journal Science Advances. Their engineered tissues have a lifespan of two to three weeks, which is not enough time for hair shafts to develop. However, the team is working on processes that will allow the hair follicle to mature further and facilitate their use in drug testing and skin grafts.
“Right now, contemporary skin models — the engineered structures that mimic human skin — are quite simple. Increasing their complexity by adding hair follicles would give us even more information about how skin interacts with topical products,” said Carolina Catarino, Ph.D., first author of the study, who earned her doctorate at Rensselaer and is now a researcher developing new skin testing methods at Grupo Boticário, a cosmetics company in her home country of Brazil.
The scientists describe the 3D printing process. They begin by allowing samples of skin and follicle cells to divide and multiply in the lab until there are enough printable cells. Next, the researchers mix each type of cell with proteins and other materials to create the “bio-ink” used by the printer. Using an extremely thin needle to deposit the bio-ink, the printer builds the skin layer by layer, while also creating channels for depositing the hair cells. Over time, the skin cells migrate to these channels surrounding the hair cells, mirroring the follicle structures present in real skin.