Regenerative medicine: a surgeon's perspective.

More than 200 million incisions are made in the world each year on children and adults. They all end up with a scar unless there is an unusual situation where we are operating on an early gestation fetus. The question is, "why do we not regenerate?" and "why do we always heal with either a 'normal amount of scarring' or, approximately 15% of the time, with a pathologic amount of scarring (hypertrophic scar or keloid)?"