regeneration

A ~60 year woman come in. Her hand was amputed at her 30's. No operation was done at that time. To my amazement, the amputated end showed some signs of regeneration. There is tiny bit of finger nail on each finger tip that was cut down to the proximal phalanx at least! So the cells at the broken end is able to transform due to the injury. So is it possible there is some chemical in the body when applied to the amputated part the body, the part just regenerate like the broken end of tree and a new branch can be formed? Sounds like science ficiton.