Biological mechanism that controls regeneration in zebrafish isolated.
At the Duke University Medical Center, biologists have been working with zebrafish, a common aquarium fish with unusual properties, namely, they can regenerate damaged limbs and organs, including fully functional eyes and hearts. They can re-grow an entire fin in approximately two weeks' time assuming that the fish is otherwise healthy. As it turns out, very small pieces of RNA (ribonucleic acid, which is involved in the synthesis of proteins, as well as controlling the state of certain genes) control whether or not the regeneration mechanism is active or not. If a particular micro-RNA strand, designated miR-133, has a low concentration in a particular zebrafish, the fish's metabolism fires up and cells begin to replicate to re-form the injured organ or limb (if a fish's fins can properly be called limbs).
This is important because it is believed by many in the fields of cellular biology and medicine that human bodies have the same innate capacity for regeneration that less advanced forms of life have. The problem is that, if such a capacity exists, it is deactivated in the human genome. If it doesn't exist, then the technical challenge of implementing it is on the table. Due to the fact that micro-RNA is found in a great many forms of life (I'm not conversant enough in the topic to state definitively if it's in all forms of life on this planet, so I'll not paint too wide a swath with this particular brush) and cellular replication is pretty much the same across all species, the same (or a similar) mechanism to that in zebrafish may be at work in humans, meaning that there very well could be a way to enable the ability to re-grow or regenerate badly damaged organs or limbs. Only time will tell.