Even with 15 percent of their hearts removed, newborn mice possess the extraordinary ability to mend themselves, researchers report today in the journal Science. It’s the first time that mammals outside of the womb have shown the regenerative ability to repair the heart.
Only newborn mice could regenerate part of their hearts, and they lost this ability after about a week after birth. Still, the results were quite impressive: Olson’s team removed 15 percent of the heart one day after birth, and when the researchers checked up three weeks later, the whole heart was repaired in 99 percent of the mice. Until now, scientists had seen fish and amphibians regenerate heart tissue as adults, but only embryonic mammals had been spotted doing the same.
“When a person has a heart attack and heart muscle cells are lost, the heart loses pump function, causing heart failure and eventual death,” said Eric Olson, a molecular biologist at Southwestern Medical Centre in Dallas, Texas. “Now that we know that the mammalian heart indeed possesses the potential to regenerate, at least early in life, we can begin to search for drugs or genes or other things that might reawaken this potential in the adult heart of mice and eventually of humans.” [The Guardian]
First they have to understand what the newborn rodent’s bodies are up to. Initially, Olson and colleagues weren’t sure how the mice were mending themselves—with stem cells, or cells that had already become muscle cells. But the appearance of the cells gave them away, says Dr. Stephen Badylak, who wasn’t involved in the study.
If a young tadpole loses its tail, no problem—it can grow a new one. Biologist Michael Levin and his team experimented with this amphibian talent, and they say they found the signal that triggers the regeneration: sodium. If scientists can find the trigger in tadpoles, perhaps someday they could find triggers for other species. Maybe even humans.
By using drugs to prompt a flood of sodium ions into injured nerve cells, biologists from Tufts University were able to regenerate severed tadpole tails — complex appendages containing spinal cord, muscle and other tissue. [LiveScience]