While scientists have become rather adept at transforming generic skin cells into specialized organ cells, crafting the organs themselves has proven far more difficult. Since the 3-D architecture of most organs is as important to their function as their cellular makeup, 2-D cell cultures are not very useful for building a replacement heart from scratch. To solve that problem, most organ makers create a scaffolding for the cells to grow on.
For a team of researchers at Rice University, even a biodegradable scaffolding wasn't good enough. By injecting cells with a metallic gel, the researchers have succeeded in suspending cultured cells in a three-dimensional magnetic field. With this magnetic scaffolding, organs can be grown in the right shape, and with no foreign material.