A small group Researchers from the University of Minnesota have finally grown a functioning heart in a lab. Whether or not you think it is ethical, you still have to admit that this is a remarkable leap for the future of science.

What makes is even more amazing is that, unlike other transplant researchers, these guys didn’t use stem cells.

But just because stem cells were used, that doesn’t mean the controversy is waived away. The heart was constructed by cardiomyocytes (heart cells) from new borns rats that were injected to old hearts from dead lab rats. Still, the scientists insist that they just “gave nature the tools, and let nature take it’s course.”