Way back in 1999 Colin Jahoda did this landmark experiment:
“Smal punch biopsies were taken from his scalp skin and from the hair follicle end bulbs dermal sheath and dermal papillae were isolated. Up to 11 pieces of dermal sheath were combined and implanted into small, shallow wounds on the inner forearm of his wife.”
From what I remember scalp hair actually grew from his wife’s forearm and the conclusion was that these follicular cells which were transplanted were special. They have some kind of immunity privilege where they are not rejected by the recipient’s immune system.
Why hasn’t this been explored? Seems like it may have been promising but perhaps I am naive.