This beats a spoonful of sugar. If pancreatic cells don’t generate insulin, why not implant cells that do? Trouble is, they would immediately be attacked by the immune system. So scientists have devised a solution: They’re 3-D printing armor — a mixture of alginate and gelatin — for the cells, enabling them to do their jobs without being destroyed. It’s not viable for human use yet, but it’s working in lab tests, and researchers are hopeful that refinement will lead to a breakthrough.