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The printed organs coming to a body near you

From kidneys to hands, 3D printers are churning out made-to-order bones and rudimentary organs.

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Frank Wojciechowski

The increasing sophistication of 3D printing is shown in an ear that melds biological and electronic parts.

The advent of three-dimensional (3D) printing has generated a swell of interest in artificial organs meant to replace, or even enhance, human machinery.

Printed organs, such as a proto­type outer ear developed by researchers at Princeton University in New Jersey and Johns Hopkins University in Baltimore, Maryland, will be on the agenda at the Inside 3D Printing conference in New York on 15–17 April. The ear is printed from a range of materials: a hydrogel to form an ear-shaped scaffold, cells that will grow to form cartilage, and silver nanoparticles to form an antenna (M. S. Mannoor et al. Nano Lett. 13, 2634−2639; 2013). The device is just one example of the increasing versatility of 3D printing.

The New York meeting, which bills itself as the largest event in the industry, will have plenty of widgets and novelties on display. But it will also feature serious discussions on the emerging market for printed body parts (see gallery for some of the latest results).

That business is currently focused on titanium replacement hip joints, which can be tailored to fit individual people, and made-to-order polymer bones to reconstruct damaged skulls and fingers. Printed body parts brought in US$537 million last year, up about 30% on the previous year, says Terry Wohlers, president of Wohlers Associates, a business consultancy firm in Fort Collins, Colorado, that specializes in 3D printing.

Scientists are looking ahead to radical emerging technologies that use live cells as ‘ink’, assembling them layer-by-layer into rudimentary tissues, says Jennifer Lewis, a bioengineer at Harvard University in Cambridge, Massachusetts. Bioprinting firm Organovo of San Diego, California, already sells such tissues to researchers aiming to test experimental drugs for toxicity to liver cells. The company’s next step will be to provide printed tissue patches to repair damaged livers in humans, says Organovo’s chief executive, Keith Murphy.

Lewis hesitates to say that 3D printing will ever yield whole organs to relieve the shortage of kidneys and livers available for transplant. “I would love for that to be true,” she says. “But these are highly complicated architectures.”

  1. At the Inside 3D Printing conference this week in New York, researchers from academia and industry are gathering to discuss the growing interest in using three-dimensional (3D) printing to make replacement body parts. Although surgeons are already using 3D-printed metal and plastic implants to replace bones, researchers are looking ahead to printing organs using cells as 'ink'. The structures shown here were all 3D printed at Wake Forest Baptist Medical Center in Winston-Salem, North Carolina, and include a rudimentary proto-kidney (top left), complete with living cells.

    Wake Forest Baptist Medical Center

  2. Printed structures made of hard metal or polymers are already on the market for people in need of an artificial hip, finger bone or facial reconstruction. This skull implant (grey) made by Oxford Performance Materials of South Windsor, Connecticut, was approved by US regulators in 2013. It is made of a polymer meant to encourage bone growth, to aid integration of the implant into the surrounding skeleton. The company also sells implants for facial reconstruction and for replacing small bones in the feet and hands.

    Oxford Performance Materials

  3. 3D printing can also be used to generate cheap — and creative — prostheses. A prosthetic hand can cost thousands of dollars, a burdensome expense when fitting it to a growing child. Jon Schull founded e-NABLE to provide free printed prosthetics to those in need, harnessing the efforts of hundreds of volunteers who own consumer-grade 3D printers. “When people get tired of printing Star Wars figurines, they give us a call,” he says. The cost of materials for a printed prosthesis is about US$35.

    Jen Owen

  4. Prostheses are not just for humans. When a duck named Buttercup was born with its left foot turned backwards, Feathered Angels Waterfowl Sanctuary in Arlington, Tennessee, arranged for the fowl to receive a new foot, complete with a bendable ankle. Also in the 3D-printing menagerie: an eagle, a box turtle and a handful of dogs — all sporting printed prostheses.

    Feathered Angels Waterfowl Sanctuary

  5. One of the key advantages of using 3D printing for surgical implants is the opportunity to model the implant to fit the patient. This airway splint (shown on the right branch of the model trachea) was designed by researchers at the University of Michigan in Ann Arbor to fit an infant with a damaged airway. The splint was made out of a material that is gradually absorbed by the body as the airway heals. The research team benefited from the concentration of 3D-printing expertise that has built up in Michigan because of the US automobile industry, which uses the technology for printing prototypes and design samples.

    University of Michigan Health System

  6. The dream of bioprinting is to print organs that can be used for transplant. At the Wake Forest Baptist Medical Center in Winston-Salem, North Carolina, researchers are developing a 3D-printed kidney. The project is in its early stages and the kidney is far from functional. Some are doubtful that researchers will ever be able to print such a complex organ. A more achievable near-term goal, they say, is to print sheets of kidney tissue that could be grafted onto existing kidneys.

    Wake Forest Baptist Medical Center

  7. One of the biggest challenges for printing functional organs is creating the vasculature that will carry blood and nutrients to the organ's cells. Last year, a team led by Jennifer Lewis, a materials scientist at Harvard University in Cambridge, Massachusetts, found a solution: a 'fugitive ink' made from a material that melts into a liquid as it cools. Once the vasculature is printed, the researchers allow it to cool, then suction off the ink as it melts. The result: hollow channels that could serve as blood vessels.

    David Kolesky and Jennifer Lewis

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