From food to firearms to full-size homes, 3-D printers have the potential to remake manufacturing, one razor-thin layer at a time. But nowhere, perhaps, is that potential more exciting than in the field of medicine, where pills cost hundreds of dollars, medical devices cost tens of thousands and organ transplants and follow-up care can cost millions.
Already, medical researchers are using 3-D printers - which convert precise digital models into real-life objects, layer by layer, cell by cell - to create stents and thin layers of biological tissue. Pharmaceuticals and artificial joints could be next.
After that? Perhaps muscles, bones, skin and - many years from now - even simple organs.
"Bio-printing means different things to different people," said Michael Renard, executive vice president of commercial operations with Organovo, a San Diego company.
Check out Part One: "Rethinking the way we pay for care" with video from a public forum on the topic.
So-called "chemputers" already are being tested and could one day be used to "print" medicinal drugs at home (and which could also be used, in theory, to print illicit ones). Some companies and university-based research labs are working on printing inorganic, but "bio-compatible," prosthetics, joints and cartilage.
That's the low-hanging fruit. The next level are hybrids - inorganic devices and tissues that have been suffused with living cells, to make those materials more life-like over time, or to allow them to degrade over time, allowing them to be fully replaced by living materials.
Then come the fully organic materials, the holy grail of tissue engineering. Organovo is working in this realm, creating small tissue and disease samples that can be used for research.
"Much like the ink comes out of your printer, [the] material coming out of our printers is the cells," Mr. Renard said. The trick, he said, is arranging those cells and materials in a precise order and shape that renders them usable, either scientifically or therapeutically.
Breakthroughs are coming every year. One at the University of Michigan helped save the life of a Youngstown, Ohio, infant - doctors used a 3-D printer to build a hose-like splint to help keep open the airway of a 3-month-old boy named Kaiba Gionfriddo.
His weakened airway kept collapsing, making it difficult for him to breathe, but the splint - implanted in February 2012, and written about a year later in the New England Journal of Medicine - helps keep the trachea open. It's made of "bio-resorbable" plastics, meant to dissolve into the body within three years of the surgery.
Those degradable materials are the most immediately useful of the 3-D printer creations, said William R. Wagner, director of the McGowan Institute for Regenerative Medicine at the University of Pittsburgh. Right now, among other projects, the institute is working on printable metals, magnesium-based alloys that break down in the body.
Because certain magnesium alloys corrode when placed in aqueous substances, they can serve as temporary scaffolding for cardiovascular and orthopedic devices.
"The key to 3-D printing is, 'What's the stuff?' " Dr. Wagner said. "How is it going to be printable?" Just because you can design a model of an organ, he said, doesn't mean it will work.
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"You can get a 3-D shape, but can't print the complexity of interaction between cells," he said. In other words, while the 3-D printer is a sexy tool, with untold manufacturing applications, it might not always be the best tool in the health care field.
Even with the precise ability to "print" organic material cell by cell, certain creations will remain elusively in the science fiction realm. Printing an eyeball, for example, seems impossible for even pioneers in the field to imagine.
"And even if you printed it up," Dr. Wagner joked, "hooking it up would be a problem ... People get a little bit ahead of themselves, thinking you're going to hit a button and get a liver."
But others, such as Organovo and the Cardiovascular Innovation Institute in Louisville, Ky., are more bullish on the possibility of making working organs. They may not be mirror-image replicas of human organs - but then again, they may not have to be.
Our bodies and our organs, Mr. Renard said, have lots of redundancies built into them, and it may not be necessary to incorporate all of those functions into the new, 3-D printer versions.
"As you think about maybe providing a liver in the future, [maybe] it doesn't have to be an anatomically correct four-lobed liver," he said, particularly if they are being used for research.
Just last month, scientists at the Cardiovascular Innovation Institute announced that it might soon be able to build "bioficial" (a portmanteau of "biological" and "artificial") heart, by printing the heart valve by valve and vein by vein.
The researchers hope to print and assemble an entire heart within five years, and hope it might be used in humans within a decade.
"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," Anthony Atala, a Wake Forest University researcher who is hoping to use 3-D printers to build a human kidney, told the Associated Press.
Any tissues and technology created by 3-D printers - or by any other means - would still need years of vetting by the U.S. Food and Drug Administration if they were to be used in humans.
First Published: May 24, 2014, 11:41 p.m.
