https://www.dailymail.co.uk/health/article-12804951/Stop-balding-process-injecting-body-fat.html
Although this is not a scientific paper, we know that body fat contains stem cells, so it is not unreasonable to expect that injecting fat cells into a scalp might stimulate hair growth. I would imagine, however, that these hairs will require continuous injections to keep them there. The hair that grows is indeed the original native hairs whose stem cells were still present. Unlike a hair transplant that brings genetically lifetime hairs to the balding area, these hairs will likely require continuous injections to keep them growing.