organs

When most people hear the phrase "organ transplantation," they generally think of allotransplantation, that is, the transplantation of organs from one person (allo=other) to a second person. Transplanted organs may come from a cadaver, as in heart transplants, or from a living donor, as with some kidney and liver transplants. Allotransplantation requires the use of immunosuppressive drugs. Patients who receive donor organs must take a special medication regimen for the rest of their lives to prevent their bodies from rejecting the "foreign" donor organs.

Almost 100,000 people languish on organ-transplant waiting lists. But new tissue-fabrication techniques should make swapping in a man-made liver as easy as snapping Lego bricks into place.

Blood vessels
Method: 3-D printer
When: 5 years
Gabor Forgacs, a tissue engineer at the University of Missouri, is making blood-vessel networks by culturing three types of vessel cells and loading them into a fridge-size bioprinter. This machine prints out the cells to build capillaries in preprogrammed patterns.