What the Latest Regeneration Research Doesn't Tell Us

Headlines are easy. Science is hard. Writers who just scan headlines of articles and papers written by others can generate some fanciful, unrealistic, and just plain wrong headlines of their own:

• Map of Lizard DNA Reveals Secrets of Regeneration: Why We Can Never Defeat the Reptilians
• DNA Regeneration Discovery Explains Why Godzilla Can Not Really Beat the Rhedosaurus
• NSA Using Zebrafish DNA to Clone Body Parts of Espionage Suspects

These kinds of headlines of ridiculous, but more importantly, they obscure the process through which real people may someday soon benefit from this kind of technology. Here's what is important to know.

• Regeneration of human limbs through this technology does not require splicing genes from zebrafish, lizards, salamanders, fruit flies, or mice into human DNA. The objective is to enhance existing DNA, not to replace it with the DNA of other creatures.
• It's much more likely that this kind of technology will be used to regenerate heart tissues before it is used to regenerate lost limbs. There is already experience with regeneration of cardiovascular tissue. Without any medical intervention at all, some people grow collateral blood vessels that take over when original arteries are blocked by atherosclerosis. This kind of gene therapy wouldn't enable recipients to grow an entirely new heart. It would allow them, possibly, to repair a heart damaged by heart attack or some other kind of cardiomyopathy. Regenerating missing limbs would be an even more complex process.
• Gene therapy is usually accomplished by genetically modifying a virus to carry the gene into the cells that need it. That's what viruses do. They carry their own DNA or RNA into cells to replicate themselves. Gene therapy uses the infective principle to carry desirable DNA into a group of cells that can benefit from genetic repair. Retroviruses, like HIV (which is not used in gene therapy), are very effective at carrying target DNA into the cells being treated, but the problem is that they may also splice DNA where it can interfere with the function of the cell. That's why one of the side effects of gene therapy with Retroviruses has often been leukemia.
• Another method of genetic modification for treating disease is out-of-body DNA modification. Doctors take a sample of bone marrow, blood, or fat and separate out stem cells. The stem cells are cultured in the laboratory to produce a large number. Then the stem cells are treated in specific ways to turn into the desired cells that can repair tissues.

READ Ten Things About Stem Cell Transplants Potential Recipients Need To Know

Turning a mass of stem cells into a functioning arm or leg so amputees would not have to use prosthetic arms or legs, however, would require a huge number of intermediate steps. Such a limb would have to include bone and blood vessels and muscles and connective tissues and skin, all of which develop differentially. For this reason, growing a human limb will probably not be accomplished in the lab. Somehow stem cell researchers will have to learn how to stimulate just enough of the human body's dormant regenerative processes to restore desirable limbs without dangerous, cancerous tissues.