The study carried out by Xiaowei Xu, MD, PhD, and colleagues at the University of Pennsylvania, shows potential to reverse hair loss using stem cells to regenerate the missing or dying hair follicles.
The team found that the epithelial stem cells, when implanted into immunocompromised mice, regenerated the different cell types of human skin and hair follicles, and even produced a structurally recognizable hair shaft, raising the possibility that they may eventually enable hair regeneration in people.
"This is the first time anyone has made scalable amounts of epithelial stem cells that are capable of generating the epithelial component of hair follicles," says Xu. And those cells have many potential applications, he adds, including wound healing, cosmetics, and hair regeneration.
Xu and his team, which includes researchers from Penn's departments of Dermatology and Biology, as well as the New Jersey Institute of Technology, started with human skin cells called dermal fibroblasts and added three genes, converting those cells into induced pluripotent stem cells (iPSCs).
These cells have the capability to differentiate into any cell types in the body and then converted the iPS cells into epithelial stem cells, normally found at the bulge of hair follicles.
The research team demonstrated that by carefully controlling the timing of the growth factors the cells received, they could force the iPSCs to generate large numbers of epithelial stem cells.
The team's protocol succeeded in turning over 25% of the iPSCs into epithelial stem cells in 18 days, which were then purified using the proteins they expressed on their surfaces.
Further research needed
While the results showed that the team had succeeded in producing the cells they set out to make in the first place, it is still too early to test in human subjects according to Xu, although it is encouraging.
"When a person loses hair, they lose both types of cells." Xu explains. "We have solved one major problem, the epithelial component of the hair follicle. We need to figure out a way to also make new dermal papillae cells, and no one has figured that part out yet."
The process Xu and his team used to create iPSCs involves genetic modification of human cells with genes encoding oncogenic proteins and so needs more refinement; however he notes that stem cell researchers are developing more workarounds, including strategies using only chemical agents.
Ruifeng Yang, Ying Zheng, Michelle Burrows, Shujing Liu, Zhi Wei, Arben Nace, Wei Guo, Suresh Kumar, George Cotsarelis, Xiaowei Xu. Generation of folliculogenic human epithelial stem cells from induced pluripotent stem cells. Nature Communications, 2014; 5 DOI: 10.1038/ncomms4071