The wonders of experimentation!
Australian* scientists have now created mice that grow back vital organs suchs as the heart and lung or entire limbs in the case of damage. The only thing they can’t regrow is a brain. Rather a useful skill, though. I’m sure the ultimate goal is to genetically engineer humans to do the same thing. I’m sure it would come in handy on occasion.
EDIT: * As Mitchell points out, the scientists are not actually Australian. My apologies for the error. I should have said “The Australian has reported that…” instead.