Growing muscles and tendons on a humanoid like the University of Tokyo's Kenshiro robot however, would allow transplants to work because it has "structures, dimensions, and mechanics similar to those of the human body," say Mouthuy and Carr. Healthy tissue needed for a hand, could be grown on an actual robotic hand, a leg tendon on a leg. What's more this would be a step toward "biohybrid humanoids" – bots of the future whose human muscles, tendons, and skin can self-repair. Dressing up robots in human tissue isn't the only way scientists are using tech to innovate transplants: medical researchers in Spain are already using patient cells to 3D-print human skin. The process could transform millions of lives, say scientists from Charles III University of Madrid – in particular the 11m people who become burn victims each year.