Not exactly the tip, but I sliced a good 1/8" or so off my thumb print once with a table saw. I was very impressed that my thumbprint mostly grew back, except for some scar pattern in the middle.
I lost the upper phalanx of one of my thumbs when I was 6 years old in an accident. They could not attach it and never grew back. 10 years later I read about an American scientist that managed to grow back full body parts using some kind of pigs but extract... I wish that science was more advanced.