Right now, about 84,000 people in the United States are waiting and hoping for new livers, hearts, and other essential organs to save their lives. Unfortunately, their hopes for a better future rely on tragedy for others—organs are donated by people who have agreed to share theirs when they die. But even when organs become available, they need to be good matches in blood type, size, and other factors in order for the operation to succeed. This is why many patients wait years for new organs; it’s a problem with no easy solution.

But what if doctors could instead make new organs for people as needed? It sounds like something you might expect to find in the infirmary at Hogwarts, but scientists are actually inventing ways to “print” organs. Researchers can scan the patient to determine the size and shape of the failing organ, and then use a 3-D printer loaded with collagen (a structural protein that gives shape to otherwise amorphous blobs of cells) instead of ink, to create a custom-made organ scaffold. Doctors can then “plant” cells from the patient—often from bone marrow—onto the scaffold and let them multiply.

Researchers don’t yet know how to print fully functioning organs like a lung, which is made up of several different types of cells and requires complicated networks of blood vessels to work properly. (So hold on to your broomsticks, Quidditch enthusiasts.) Yet they are making progress. Some have grown skin and other tissues from tailor-made scaffolds to treat patients for burns, birth defects, and injuries. (Pitt’s Rocky Tuan has grown living cartilage.) Some are starting to use 3-D printed scaffolds as guides in surgery. And others have conjured up 3-D generated models to better understand molecular structures and how the body works its magic.