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3D Printing: A Matter of Life and Death


When Kaiba Gionfriddo was born prematurely on 28 October 2011, everything seemed relatively normal. At 35 weeks, his doctors’ main concern was lung development, but Kaiba was breathing just fine. Doctors deemed him healthy enough to send him home within a few days. Six weeks later, Kaiba stopped breathing and turned blue. After 10 days in the hospital and another incident, physicians diagnosed the infant with severe tracheobronchomalacia, a condition where there is a weakened windpipe so that the trachea and left bronchus collapse, preventing crucial airflow from reaching the lungs. Kaiba then underwent a tracheostomy and was put on a ventilator, the typical treatment for this condition. However, it didn’t work. Since the prognosis was not good, his doctors tried something revolutionary: a 3D-printed lung splint that could save his life.


Glenn Green, MD, associate professor of pediatric otolaryngology at the University of Michigan, and colleague Scott Hollister, PhD, professor of biomedical engineering and associate professor of surgery, used 3D printing technology to create a bioresorbable device that instantly helped Kaiba breathe. It’s a prime example of how 3D printing is transforming healthcare as we know it. Green and Hollister had already developed a prototype of the 3D-printed splint, a sort of tubular scaffolding designed to fit around a patient’s airway and inflate his bronchus and trachea.



Scott Hollister, PhD, left, and Glenn Green, MD Image: University of Michigan Health System.



Approximately 1 in 2,200 babies is born with tracheomalacia, a condition in which the tracheal cartilage softens and leads to collapse.


Yet while 3D printing is changing the way consumers think about mass manufacturing, a parallel revolution is only gradually entering the mainstream consciousness. Behind the scenes, doctors and biomedical engineers are experimenting with the technology, already saving and otherwise improving lives in the process. So far, 3D printing has helped produce jaw transplants, skull implants, millions of hearing aids and a wide variety of prosthetics – for both humans and other animals. Some scientists have developed 3D printers (“bioprinters”) that print layers of skin tissue, artificial blood cells, miniature human livers and even bionic ears.


In cases with tracheomalacia, doctors once treated many of these instances with traditional solutions. Technicians handcrafted hearing aids and dental appliances from molds; doctors fitted prosthetics to residual limbs; patients received transplants, albeit slowly, from viable donors. The difference is 3D printing allows for speed, efficiency and customization, three factors that can make a life-altering – hopefully life-saving – difference.


The technology behind conventional 3D printing is fairly simple to explain. After a 3D printer reads the design you’ve created with computer software, it passes over a platform, much like an inkjet printer, and deposits the desired material in layers. The process varies according to the model and the size of the object, but a 3D printer typically sprays, squeezes or otherwise transfers a material onto the platform in a matter of hours.


To create Kaiba’s tracheal splint, Green and Hollister obtained emergency clearance from the FDA and then took a CT scan of his trachea and bronchus to produce a precise image, from which they could design the device. Using computer modeling software and making some modifications, they created a splint that perfectly matched Kaiba’s windpipe and printed it with a biodegradable polyester called polycaprolactone.


The custom splint fits around Kaiba’s airway, and it will dissolve within three years. Image: University of Michigan Health System


The splint goes around the outside of the bronchus, then sutures pass through the splint to tether the trachea through the inside. This expands the bronchus and inflates the trachea. With growth, the splint opens up. Even though Green and Hollister sized the design to Kaiba’s bronchus, they crafted three or four increments of about a half a millimeter above and below the diameter from his scan. Then they made about five copies of each, just to make sure they had enough going into the operating room. When they implanted the splint on 9 February 2012, it established an opening in the bronchus. Kaiba’s lungs immediately started moving. The surgeons expect the device to dissolve completely within three years, when Kaiba’s windpipe will have grown in the correct dimensions, big enough that it won’t further collapse. As a surgeon, Green explains that he can’t match the ability of a computer specifically tailored to a patient’s image. “There are a bunch of things that I hand-carve or hand-make,” he says. “My abilities are down to around a millimeter, maybe. I can get a microscope out for some small applications, but to do that in the operating room, to go sub-millimeter resolution, is not worthwhile. And I can’t do it with a big case like [Kaiba’s]. It’d be impossible to do.”


The splint, in this particular case, was inserted at no cost to the family, since it was considered a research project. Green explains, however, that the initial price for such devices in the future will be relatively high, because of expenses associated with purchasing the 3D printer, the sterilization, etc. That said, the raw material is very inexpensive – the polycaprolactone splint costs less than $10, and it can be fashioned in about 24 hours.


An iconic painting hangs at the Countway Library at Harvard Medical School. The scene shows a gaggle of physicians crowded around two patients on operating tables – one in the front room, another in the back, almost as if mirroring each other. Men in white lab coats stand outside the doorway on the right, hanging slightly past the frame, talking excitedly while pointing to their notepads. Something important is about to happen. The painting depicts the first human organ transplant in history – a kidney, in 1954. Anthony Atala, MD, director and chair of Wake Forest Institute for Regenerative Medicine in North Carolina, projected the painting onto a screen before beginning his October 2009 TED Talk. Wake Forest is one of the largest facilities in the world dedicated to regenerative medicine. Its scientists were the first to engineer lab-grown organs – human bladders – which they successfully implanted into seven patients at Boston Children’s Hospital in 2006.


The biomaterials used in regenerative medicine are essentially materials compatible with the body. They can be natural (like collagen), synthetic or a combination of the two. Biomedical engineers can weave biomaterials together, or they can print them, similar to how Kaiba’s doctors manufactured his splint. As a result of this bioprinting technology, scientists at the Wake Forest Institute 3D-printed a kidney in seven hours, using biomaterial and human cells.


Bioprinting is similar to conventional 3D printing in that it’s a combination of related technologies used to print out living structures, and each one has its own process, limitations and potential achievements.


Autodesk, one of the leaders in computer-aided design software since it was founded in 1982, has worked to push innovation in 3D bioprinting for the past three years. Essentially, the company is trying to look at life as a design space.


Anthony Atala, MD, holds a printed human kidney, with the printer in the background. Image: Flickr, Steve Jurvetson


One of the things that makes bioprinting different from conventional printing is that the design software has to understand biology as well as the mechanical aspects of the designs. With traditional CAD software for a conventionally 3D-printed object, the design and geometry has to be specified. With bioprinting, the CAD software has to understand the biochemistry of it, too – things such as metabolism and nutrient diffusion.


Today, the team at the Wake Forest Institute works to engineer replacement tissues and organs, and to develop cell therapies for more than 30 different areas of the body. It’s currently developing a specialized 3D printer as part of the Armed Forces Institute of Regenerative Medicine, a federally funded initiative to apply regenerative medicine to battlefield injuries. In other words, this printer may be able to print skin grafts directly onto patients’ wounds.


There’s currently no standard software for 3D bioprinting, and therefore, no practical way for the community to exchange designs. Now, Autodesk is developing Project Cyborg, a platform to enable researchers and scientists to develop computational models and receive information in a more open and accessible way. Despite no standard way to create and share designs, 3D printing is filling the holes left behind by traditional medicine.


Kaiba was taken off ventilator support 21 days following the splint procedure, and he hasn’t had any trouble breathing since then. He still has regular and relatively close follow-up appointments at the University of Michigan. He uses a valve to talk. He’s mildly delayed in physical development, which Green says is unsurprising, considering how long Kaiba was paralyzed. But Kaiba still looks and acts like a normal kid, playing with his brother and sister and hanging out with the family dog, Bandit. He even gets himself into trouble, scooting across the floor and “getting into everything,” according to his mom. Source: Sept 2013



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