Cellular regeneration is something you probably thought was only allowed for a few choice humans, like say David Tennant or Ryan Reynolds, and most of the time you probably watched it happen on one of those fancy moving picture screens. When I was a kid I was also way jealous of those cool geckos and axolotls (mainly because they were cute as hell) but really because if they got into a brawl and suffered a little decapitation or loss of limb, they could just ‘dedifferentiate and chill’ and grow those puppies back.
In reality though, us humans deserve a lot more credit for our regenerative qualities. If we put scabs and scars to the side, humans have been found to regenerate fingertips, toes, and even our Kidneys and Liver! A human Liver can completely remake itself from only a quarter of its tissue, and is a very impressive example of cell proliferation. Recently though, there have been some ground breaking leaps in the field of induced regeneration in humans. Grafts of the bladder, heart, and lungs have all been successfully engineered and put to use in the repair of failing organs. Most interesting is the tale of Polish fireman Darek Fidyka, who underwent a procedure via the use of stem cells and cells from his olfactory bulbs (smell cells) to cure his paraplegia. He gained movement and sensation in his limbs, and can now walk and drive.
So, regeneration of the Wade Wilson style is not really as far away as you think. But, just for the sake of argument, I wouldn’t go sparring with Colossus anytime soon, or you might end up looking like Jabba the Hutt.