gdf 11. >> science in action here. >> now, mice don't get a heart disease like humans do but they mightus clues how to fight it. here at harvard, researchers are trying to follow these clues, trying to fight a cardiac cries i, maybe young ones will heal old ones. >> the blood has access to all these different cells and tissues and may be able to communicate these aging signals. >> there may be thousands of factors that circulate in the blood. how did did yo did you isolate e protein you didn't know you were looking for? >> we collaborated with a company in colorado. >> specific marker in the blood to help identify the protein. >> it's kind of like having bar codes on thousands of post-it notes. and that by using those different-colored post-it notes and finderring the right things -- finding the right things then they can picks out and find out what it was. >> it was incredible inc. do these approaches because it was like looking for a needle in a haystack. >>> the way you discover something at least the way you two did, for that fleeting moment before you publish it you know something