The 3D printed heart


From a human ear, to perfectly functioning valves, 3D printers are already being used in medicine, but now scientists in the US are attempting to build a whole human heart using the versatile piece of kit.
Their ultimate goal is to create a new heart for a patient using their own cells that could be transplanted.
It is an ambitious project to first make a heart and then get it to work in a patient and it could be years - perhaps decades - before a 3D printed heart would be put in a person in a standard operating theatre.
The technology, though, is not all that futuristic. Researchers have already used 3D printers to make splints, valves and even a human ear.
So far, the University of Louisville in Kentucky has printed human heart valves and small veins with cells, said Stuart Williams, a cell biologist leading the ambitious project.
They have also successfully tested the tiny blood vessels in mice and other small animals and Professor Williams believes scientists will be able to print parts and assemble an entire heart in three to five years.
The finished product would be called the ‘bioficial heart’ - a blend of the natural and artificial.
The biggest challenge is to get the cells to work together as they do in a normal heart, said Professor Williams, who heads the project at the Cardiovascular Innovation Institute, which is a partnership between the university and Jewish Hospital in Louisville.
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, he said.
If everything goes according to plan, Professor Williams believes the heart could 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 ones, including children whose chests are too small for an artificial organ.
Professor Williams said the heart he envisaged 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.
Dr Anthony Atala, whose team at Wake Forest University in North Carolina is using 3D printers to attempt to make a human kidney, said: ‘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’.
The 3D printing approach is not the only strategy researchers are investigating to build a heart out of a patient’s own cells. Elsewhere, scientists are exploring the idea of putting the cells into a mould. 
Scientists have already created rodent hearts that beat in the laboratory and some simple body parts made using this method have already been implanted in people, including bladders and windpipes.
The 3D 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. 
Professor Williams’ printer uses a mixture of a gel and living cells to gradually build the shape. The idea is that eventually, the cells would grow together to form the tissue.
At the moment, the printer is focused on replicating parts of the heart, but in the future it could print the whole structure in less than three hours, Professor Williams told Wired. 
However, the largest blood vessels and valves will need to be printed and assembled separately.
‘Final construction will then be achieved by bioprinting and strategic placement of the valves and big vessels, he added.
The technology has already helped in other areas of medicine, including creating sure-fitting prosthetics and a splint that was printed to keep a sick child’s airway open. Doctors at Cornell University used a 3D printer last year to create an ear with living cells. 

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