3-D Printing to the Rescue | Healthcare of Tomorrow

U.S. News Hospital of Tomorrow logo

Four weeks after giving birth to twins, Tokoya Proctor cradled a three-dimensional model of her sons in her hands. Made of plastic from an MRI scan taken when Proctor was 16 weeks pregnant, it captured an exact likeness of the fetuses drowsing in her womb. Her twins were hugging, conjoined along the chest and abdomen. They shared a liver. One twin’s heart poked into his brother’s chest, wrapped in a common membrane with the second heart. « It was amazing, » she says. « It was a work of art. »

For Proctor’s medical team, it was much more: a guide to the high-risk separation surgery ahead. The model, with internal organs that snapped together like Legos, allowed doctors to visualize in advance precisely how to safely separate the twins, in an operation that would take 12 hours. When you are responsible for the lives of two infants, says surgeon Anthony Sandler, who led the 2013 operation at Children’s National Medical Center in Washington, you want « a tangible, physical feel » for the challenges to come. The tool making it possible: a 3-D printer.

The technology that is expected to be the future of manufacturing is promising to revolutionize medicine, too – just three decades after the first 3-D printer was invented by a young engineer named Charles Hull to quickly make plastic prototypes of machine parts. Instead of using ink, Hull printed out layer upon layer of acrylic in desired shapes; his fellow engineers began testing an ever-expanding list of materials. Today, the « ink » in 3-D printers includes plastics, ceramics, metals and even cooking ingredients and living cells, which can make everything from jewelry and eyeglasses to cake decorations – and body parts.

Indeed, medicine is already putting the technology to use in several areas. In surgery, where doctors have long had to rely solely on flat images for guidance, 3-D models made from those images are giving them much more information to go on. The printers make it possible to custom-build implants and prostheses, and even to use living cells as ink to create vital tissues and experimental organs such as skin and livers.

The future seems almost limitless. « I swear to God, » says Jon Schull, a research scientist at the Rochester Institute of Technology Center for Media, Arts, Games, Interaction and Creativity, « I expect to see 3-D-printed organisms if I live long enough. »

Surgical teams used to be comprised of doctors, nurses and technicians; today they may well include engineers, software experts and materials scientists, too. These pros work collaboratively at a growing array of hospitals, using 3-D printing technology to prep for operations in virtually every surgical discipline, especially pediatric and adult cardiac surgery; facial reconstructive surgery; orthopedic surgery involving the hip, knee and shoulders; neurosurgical procedures involving the skull and spine; and complex cancer surgeries requiring the removal of difficult tumors.

Research Engineer Carolyn Cochenour holds the 3-D model that was created of a set of conjoined twins that allowed doctors to visualize exactly where the babies were connected.

Research Engineer Carolyn Cochenour holds the 3-D model that was created of a set of conjoined twins that allowed doctors to visualize exactly where the babies were connected.
(Lexey Swall/Grain for USN&WR)

Surgical planning using 3-D imaging technology has become so « ubiquitous » that it’s hard to track where it’s being applied, says Scott Hollister, a University of Michigan professor of biomedical engineering who has helped pioneer 3-D printing of implants in pediatric surgery.

Major 3-D centers include Children’s National, Wake Forest University in North Carolina, C.S. Mott Children’s Hospital in Michigan, the Mayo Clinic in Minnesota and Walter Reed National Military Medical Center in Maryland, where surgeons perform complex reconstructive surgery. Three-dimensional printing has become so integral to surgery at Mayo and The Children’s Hospital of Philadelphia that 3-D labs were installed just upstairs from the operating rooms. Doctors say that the technology produces better outcomes with fewer complications and allows patients to exit the OR much sooner.

« We definitely see the impact, » says mechanical engineer Axel Krieger, who heads the 3-D lab at Children’s National and who, with cardiologist Laura Olivieri, led the team responsible for the models used in the Proctor twins’ separation. Each year, dozens of lives depend on the lab’s craftsmanship, and the margin for error is small.

In oncology, 3-D modeling is helping surgeons pinpoint which tissues to save and which to remove. A standard imaging scan of a kidney or lung riddled with cancer, for example, would show tumors in two dimensions. Locating them in a 3-D model ahead of time allows doctors to more accurately extract malignancies while preserving as much healthy tissue as possible.

At Walter Reed, 3-D technicians generate physical models displaying the unique features of each traumatic injury. Prosthetics specialists custom-design replacement body parts to fit the limb precisely. Surgeons who once had to guess at a patient’s natural jawline, eye socket or other facial structures after a traumatic injury now plan repairs using scans that allow them to design the bone graft and the cutting guide that will be used to carve it from the patient’s shinbone, says Capt. Gerald Grant, chief of Walter Reed’s 3-D Medical Applications Center. Careful planning has whittled OR time for many procedures by half, says Grant.

Hospitals that can’t afford their own 3-D labs can buy the services from corporate suppliers such as Hull’s company, 3D Systems, in Rock Hill, South Carolina. Using patient data provided by doctors, 3D Systems prints custom guides for total knee replacements that are now being used in approximately 10,000 of the 600,000 operations performed in the U.S. each year. Materialise, a Leuven, Belgium-based company that has developed software to convert flat medical scans into 3-D-printable images, says its tool has been used for approximately 225,000 surgeries worldwide. The guides help surgeons align the knee accurately for each patient between the thighbone and knee. An off-kilter knee, experts say, may affect the patient’s gait.

One day in 2011, a colleague asked Glenn Green, a pediatric ear, nose and throat specialist at the University of Michigan, « If you had a million dollars, what would you do with it? » His response: figure out a better way to treat children with a collapsed trachea, the windpipe carrying air to the lungs. Every year, approximately 2,000 children in the U.S. are born with the condition. About 100 die. Standard treatment is to punch a hole in the airway and put the child on a ventilator for months or even years. The hope is that the trachea will widen as the children grow, but there’s no guarantee. Green’s colleague hooked him up with Michigan’s Scott Hollister. After months of developing prototypes, Hollister produced a hollow tracheal splint made out of a biodegradable polyester that can be stitched into place around the airway to open it up.

Garrett Peterson of Salt Lake City was one of the lucky pioneering recipients. He was born in late 2012 with a congenital heart defect that crushed his trachea just below where it forks into his lungs, making breathing almost impossible. « He would suffocate over and over and they’d have to resuscitate him, » says his father, Jake Peterson. « He’d suddenly turn blue. » The baby spent 18 months on a ventilator before receiving two splints, to accommodate both branches of his trachea. Now able to breathe on his own, with a little oxygen support when sleeping, he has been freed from the hospital.

The procedure also drops the cost of care by as much as $1 million per patient, says Green. Manufacturing a splint and implanting it surgically costs about $250,000; placing a child on a ventilator for a year or two runs at least three times more.

Like Green and Hollister, companies and 3-D enthusiasts in major medical centers have begun to use 3-D technology to create not just models of body parts, but actual parts. The earliest innovations: synthetic patches and plugs to repair skull damage, facial implants to aid in reconstructive surgery by shoring up the orbital bone of the eye, and custom hip cups to anchor the ball in replacement hips.

Doctors at the Mayo Clinic and at medical centers throughout Europe have begun inserting the hip socket; Walter Reed and many other hospitals are producing or purchasing skull and facial implants. In early 2013, Oxford Performance Materials of South Windsor, Connecticut, became the first U.S. firm granted Food and Drug Administration approval for a 3-D-printed skull patch. Since then, the company has won FDA approval of a facial implant and a spinal implant system.

Still, overall progress is slowed by the challenges involved with getting the FDA’s blessing for 3-D-printed implants. Because many are custom-made, the structures defy standards for safety, effectiveness and uniformity used to evaluate mass-market medical devices. Many of the implants now in use are approved through emergency-use exemptions. But entrepreneurs see plenty of opportunity ahead – particularly in orthopedics, as baby boomers require new joints.

One of medicine’s biggest quandaries is obtaining fresh organs and tissues for people who need transplants, whether it’s a heart, lung, liver or the donut-shaped rings of cartilage that cushion the knee. An average of 21 people die every day in the U.S. because of organ shortages, and more than 123,000 Americans are currently on a wait list to receive a transplant. Only about 30,000 people annually get one. A small cadre of pioneering researchers has spent two decades attempting to ramp up supply by growing tissues and organs in the lab.

Nine years ago, for example, Anthony Atala, director of the Wake Forest Institute for Regenerative Medicine, reported that he had engineered lab-grown bladders that were successfully implanted into a handful of patients. But traditional methods are labor-intensive, time-consuming and complicated. Cells must be cultivated outside the body, fed chemicals known as growth factors, and draped on biodegradable scaffolds to give them the natural contours of organs.

Now, a growing number of biotech firms and academic labs, including at Cornell, Yale and Wake Forest, are experimenting with applying 3-D technology to the challenge of « printing » a wide range of tissues and organs, from livers and hearts to skin and spinal implants. « It takes a lot of people with a lot of skills » to bioengineer tissue, says Lawrence Bonassar, a professor of biomedical engineering at Cornell. But with 3-D printing, once you’ve succeeded the first time, « it takes a much lower level of skill to make it the second time. »

Just as an ink-jet printer uses multiple colors, the 3-D printing technology relies on multiple living « inks, » each made of a different type of carefully cultured human cell taken from bones, blood vessels and tissues. Over the long term, the goal is to create a three-dimensional organ with its own blood supply; at the moment, the focus is on printing blocks of functioning tissue for research. The idea is to build up the organ tissue one thin cell layer at a time around tubular channels for 3-D-printed blood vessels – thus recreating a natural organ’s detailed architecture.

Atala’s team is using standard tissue-engineering techniques in combination with 3-D printing to tackle more than half a dozen different tissues and organs, including bone, skin, muscle, kidney and ovary. The puzzle of how to create the tubular channels, into which cells could be deposited to form blood vessels, is a key current focus of Atala’s team and others. Researchers at Yale are collaborating with the San Diego-based biotech firm Organovo to use a gel as a tubular mold to which the blood cells can be applied. Once the cells knit together into blood vessels, the gel will be removed to make way for blood flow. The next step will be to make blood vessels that fork.

John Geibel, Yale’s director of surgical research, envisions rapid progress. « By fall, we’re hoping to have some animals running around with our blood vessels in them, » he says. Ultimately, his goal is to create small, functioning livers that can be used to assist a failing liver until a transplant is available. Organovo has already created functioning, 3-D-printed livers too small to serve as a human organ, which it uses for drug toxicity studies. Since the liver is able to regenerate itself, Geibel says, « we hope we wouldn’t have to design it exactly the full size. We’d make it smaller. »

The earliest successes are apt to be tissues that do not require blood vessels. Atala has developed a bedside 3-D printer that layers skin cells directly on wounds and burns; he hopes to begin human trials in five years. At Cornell, researchers are working on heart valves, spinal discs and the meniscus that cushions the knee. « This is a big deal, if we can crack this, » says Hod Lipson, a Columbia University professor of biomechanical engineering. « These are things that you now can only get from animals or cadavers. »

Hurdles clearly remain, scientific and otherwise. Beyond the questions of how to regulate the quality and safety of nonstandardized implants, there are ethical quandaries. Scientists are now in the earliest stages of experimenting with performance-enhancing body parts like bionic ears, modeled to replace lost or damaged ears and equipped with electronics that capture a richer soundscape than a normal ear. What if they created a knee that improved an athlete’s performance? « The Tour de France committee is going to have a tough time deciding what’s legal and what’s not, » says Lipson.

Meantime, Tokoya Proctor just feels grateful to be an early beneficiary. Her boys, almost 2, are healthy and active, constantly climbing in the pantry and tumbling over the baby gates. They’re inseparable, she says. But – against the odds – they’re separate.

Excerpted from U.S. News’ « Best Hospitals 2016, » the definitive consumer guidebook to U.S. hospitals. Order your copy now.

Laisser un commentaire