You say that like I actually put more thought into my post than what first occured to me.
But with some sort of medicinal wizadry I'm sure you could concoct some sort of formula of the right hormones required to stimulate the correct type of cells to grow.
People have been trying for centuries yet we stall haven't done it to any reasonable extent.
It's just hat most of tissue will just form scar tissue, and doesn't really have the ability to grow back a limb etc, hence a lot of the buzz about stem cells.