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As a media producer, one of the great things about my career is I'm always learning. That is definitely the case with this "Growing Skin" story. Wound healing and tissue regeneration is not something I've thought a lot about before. Research occurring in this field is high-tech and to me, at least, approaches a science fiction feeling.
When we interviewed Dr. Mark Carlson about the research he's conducting to develop a liquid bandage, he had some interesting things to say about tissue regeneration. As we all know, humans and other mammals don't 're-grow' skin or other parts of the body, but other creatures can.
"If you get a burn and the skin is burned away, your body cannot regenerate that lost skin. You get a scar instead,” said Carlson. “There are a lot of lower animals, salamanders, for instance, that can regenerate lost body parts. So elsewhere in the animal kingdom, the ability to regenerate does exist. But in the mammals and in humans, the ability to regenerate lost tissue, whether from an injury trauma or a cancer or loss of blood supply, whatever the mechanism of tissue injury is, a human cannot replace, except in a very small number of cases, lost tissue."
So why is that? I'd think we 'advanced' creatures would be the ones that would regenerate tissue, while the 'lower' ones like a salamander would be the ones running around without a leg or tail after losing it. Carlson explains that it might be an evolutionary sort of thing.
"When you get an injury, typically the quickest way to cover that injury up to get it to seal from the environment is by healing with a scar. And this is very important in the wild because you have to have that wound covered quickly or else it’ll get infected. So in nature, a large animal like a wolf or something gets an injury, they heal quickly with scar and that protects them in the short run. Smaller animals like salamanders etc., they’ve maintained this ability to regenerate possibly because the need to get the wound covered right away isn’t as great. This is a theory. This is not fact. But, when people try to piece together why large mammals like us don’t regenerate and small animals can, this is one of the things that commonly comes up is that there were evolutionary pressures on the large animals to recover from a wound as fast as possible, so that they would survive. So somewhere, we’ve lost the ability to regenerate."
The liquid bandage Carlson is hoping to develop is designed to stop bleeding quickly. That could be a life-saver in battlefield situations or other incidents of trauma. But he's thinking about a bigger picture too. He says one of the other research goals of regenerative medicine is to try to figure out the reasons why some creatures (mammals) react to injury with an inflammatory response and others (salamanders) take the path of regeneration. Then maybe someday, humans will 're-grow' tissue and recovery from injury could be more complete.