would you eat a burger grown from stem cells in lab? it might sound gross to some people. you might get the chance to find out. dan rivers in london with what's on the menu. are you taste testing? >> reporter: i do. this is a stem cell burger. it has been produced in lab not in a cow. it's one of only two that they made and the other one has been eaten. this is the only one in existence anywhere in the world. i better not eat it. it costs $300,000. >> that's an expensive burger. >> reporter: i'm going to put it down over here because i don't