Judging by actions and the amount of noise generated, there is much more enthusiasm for hair regeneration than for regeneration of internal organs. But it's not news that people exhibit terrible prioritization when it comes to health, aging, and supporting research. If we lived in a rational world, the development of rejuvenation biotechnologies would be massively funded now that it is a plausible goal, and restoration of hair wouldn't be high on the list of priorities, given that it doesn't kill you, and there are all too many other forms of actually fatal degeneration to reverse:
One potential approach to reversing hair loss uses stem cells to regenerate the missing or dying hair follicles. But it hasn't been possible to generate sufficient number of hair-follicle-generating stem cells - until now. [Researchers demonstrated] a method for converting adult cells into epithelial stem cells, the first time anyone has achieved this in either humans or mice. The epithelial stem cells, when implanted into immunocompromised mice, regenerated the different cell types of human skin and hair follicles, and even produced 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." Those cells have many potential applications, including wound healing, cosmetics, and hair regeneration. [They] are not yet ready for use in human subjects, [however]. A hair follicle contains epithelial cells - a cell type that lines the body's vessels and cavities - as well as a specific kind of adult stem cell called dermal papillae. "When a person loses hair, they lose both types of cells. 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."