It may sound far-fetched, but scientists are attempting to build a human heart with a 3-D printer.
Ultimately, the goal is to create a new heart for a patient with their own cells that could be transplanted. It is an ambitious project that will take many years.
But the technology is not all that futuristic: researchers have already used 3-D printers to make splints, valves and even a human ear.
So far, the University of Louisville scientists have printed human heart valves and small veins with cells, and they can construct some other parts with other methods. Stuart Williams, a cell biologist leading the project, said they also had successfully tested the tiny blood vessels in mice and other small animals.
Williams believes they can print parts and assemble an entire heart in three to five years.
The finished product would be called the "bioficial heart" - a blend of natural and artificial.
An organ built from a patient's cells could solve the rejection problem some patients have with donor organs or an artificial heart, and it could eliminate the need for anti-rejection drugs.
If everything goes according to plan, Williams said the heart might be tested in humans in less than a decade. The first patients would most likely be those with failing hearts who are not candidates for artificial hearts, including children whose chests are too small for an artificial heart.
Williams said the heart he envisioned would be built from cells taken from the patient's fat.
But plenty of difficulties remain, including understanding how to keep manufactured tissue alive after it is printed.
"With complex organs such as the kidney and heart, a major challenge is being able to provide the structure with enough oxygen to survive until it can integrate with the body," said Dr Anthony Atala, whose team at Wake Forest University is using 3-D printers to try to make a human kidney.
The 3-D printer works in much the same way an inkjet printer does, with a needle that squirts material in a predetermined pattern.
The cells would be purified in a machine, and then printing would begin in sections, using a computer model to build the heart layer by layer. Williams' printer uses a mixture of a gel and living cells to gradually build the shape. Eventually, the cells would grow together to form the tissue.