a gel it can be used in three d. printing. three d. technology is available we all know we can print non-living matter but now we're seeing it's possible to print a living matter as well. perhaps one day we might be able to print heart muscle blood vessel and connective tissue cells in just the right combination . for now the initial experiments show that heart muscle cells produced in this way can form a structure and beat synchronously for several weeks. in the future it might be possible to apply such engineer tissue to damaged areas of the heart and give it new strength. but the prospect of replacing i'm renewing heart muscle in humans is still quite distant the individual components of the printed heart tissue would have to grow together and form