PRINT ME A NEW BODY
Using 3D printers, doctors and technicians are making body parts to repair the sick and injured
3-D printing of body parts is revolutionising healthcare – and it’s just the start.
Len Chandler’s right heel had been hurting so badly that he could barely walk, but the retired builder from Rutherglen in Victoria kept going with the help of orthotics and anti-inflammatories. It wasn’t until he had an MRI that the Australian grandfather realised how serious it really was. “You’re in trouble,” said his doctor. “It’s cancer.”
Referred to orthopaedic surgeon Professor Peter Choong at St Vincent’s Hospital in Melbourne, Len was shown how a rare cancer had eaten a gaping hole in his heel bone. The only option was amputation, Professor Choong explained, since conventional implants cannot support the body’s weight or fit properly with the bones in the foot.
But in late 2014, Professor Choong had an exciting new option: he could literally “print” a new heel bone for Len.
Professor Choong ordered a detailed scan to capture the exact dimensions of Len’s good heel. Technicians at medical device company Anatomics mirrored the scans and created a digital model of Len’s missing right heel bone. This information was sent to experts at the Commonwealth Scientific and Industrial Research Organisation (CSIRO). With a sophisticated 3D printer and titanium “ink”, they set about printing a new heel for Len, layer upon microscopic layer. The revolutionary prosthesis was crafted to the finest detail, with smooth surfaces where it would contact bone, holes for the stitches and rough surfaces to allow tissue to adhere.
A few months after the operation to fit the bespoke heel, Len was driving, walking and playing with his seven grandchildren again.
PRINTING THE FUTURE Scientists developed the first basic 3D printers to replicate solid objects more than three decades ago. Today, printers routinely fashion items as large as furniture and cars, or as delicate as jewellery and microscopic parts. But it’s in healthcare that this technology promises some of the most life-changing applications. Here’s what scientists can do right now and what we can hope to see in the future.
BONE REPLACEMENTS “Bones” are a comparatively easy challenge for 3D printing. With advances in body scanning, it’s possible to map every angle and dimension of existing body parts and then customise a new implant out of plastic or metal (and ceramics, though mostly in dentistry so far), as Professor Choong did with Len’s heel.
Think of it as the difference between a tailor-made suit over one off a rack – the first is made to your exact requirements for the most elegant fit; with a ready-made outfit, invariably the trousers are too long or too short. For years patients and surgeons have been forced to pick the closest fit from the limited range of prostheses available in medical catalogues, but 3D printing allows technicians to make replacement body parts to measure.
In the Netherlands last year, a Dutch woman with a rare condition who needed a new skull received a 3D-printed cranium that was made after scanning her head. It was positioned over her brain much like a cycle helmet (see page 48). Thousands of others around the world have already
received customised sections of skull to close gaps left after head surgery. And in world firsts, 3D printing has recently been used to create a fingertip, hand bones, arm, jaw and even the bones for an entire skull in a man who crushed his face after a four-storey fall.
To replace teeth, dental labs take detailed scans and “print” accurate crowns, bridges, models and orthodontic appliances – most without having to wait for a technician to cast the parts. And the day’s not so far off when doctors will be able to print body parts on demand, right there in the operating theatre.
“One day I’ll get a patient with bone cancer, isolate the tumour with a computer, scan the patient’s leg with a CT scanner and then print
out the part I need to put back in real time,” says Professor Choong.
EASING PAIN Medical researchers are looking forward to being able to replace softer tissues such as damaged cartilage although it’s more complex to print than bone. Cartilage is the material that cushions joints as well as forms vital parts of structures such as windpipes, noses and ears.
So far, attempts to grow cartilage
or transplant it from elsewhere in the body have had limited success, says Professor Choong. But 3D printing could change that. Researchers are investigating how to print a tiny 3D scaffold, a structure resembling a dry sponge. The microscopic holes in the scaffold would then be filled with the patient’s stem cells and other chemicals needed to promote growth, and implanted exactly where doctors want the new cartilage to grow.
“We essentially speed up the development process by giving the cells everything they need, while creating a scaffold to give the tissue the exact shape and structure that we want,” Rocky Tuan, director of the Center for Cellular and Molecular Engineering at the University of Pittsburgh, explained recently.
Similar techniques will allow cartilage to be grown to form new ears and noses. Trials are currently underway of basic printed ear scaffolds that will be implanted in arms to grow skin and blood vessels before being transplanted to their proper positions.
WORKING WITH THE BODY In China last year, a boy with bone cancer in his spine received a 3Dprinted vertebra. Since it was produced to the exact dimensions he needed, it’s stronger and less likely to slip, meaning that he can return to an active life. The titanium implant was made porous, so his own bone can grow through it over time.
It’s an amazing solution, but it could be even better. “A metal bone isn’t going to have the same flex as human bone,” says Professor Gordon Wallace, director of the Intelligent Polymer Research Institute at the University of Wollongong in New South Wales. “Customised implants can provide better performance than something that’s off the shelf, but they never get the function of naturally occurring material … Ideally you would want to facilitate the body’s natural regeneration process.”
To this end, researchers are looking at “bioprinting”, using biodegradable materials such as polycaprolactone to form the printed scaffolds. They act as strong frameworks when implanted, but as the body rebuilds, break down to leave only the regrown natural tissue.
In December, researchers from the Columbia University Medical Center announced that they had used 3D bioprinting to replace the meniscus, the protective lining of the knee. A printed scaffold infused with human growth factors was implanted, prompting the body to “fill in the gaps” and regenerate the full lining.
Similar advances are being made in growing new muscle tissue, and researchers from the UK’s University of Cambridge have made progress in rebuilding retinal cells to treat blindness.
Still in its infancy, this process has potential for regenerating bone marrow and muscle, and for creating conduits that help nerves to grow across a gap. Already this technique has been used with some success to restore function to damaged fingers and limbs. “The spinal cord is everybody’s ultimate goal,” says Professor Wallace.
While printed menisci, retinal cells and the like are yet to make it from the lab to the operating theatre, there have already been astonishing successes. A toddler in the US is one of several
Babies have been saved from lifethreatening weaknesses in their windpipes by customprinted splints fitted exactly
people alive thanks to windpipes that have been made from biodegradable scaffolds seeded with the patient’s own stem cells. Other babies have been saved from life- threatening weaknesses in the cartilage rings that hold their windpipes open by custom-printed splints that can be fitted to their exact needs and which will dissolve as the children grow and their windpipes strengthen naturally.
PRINTING A WHOLE ORGAN The logical end point of printing living cells and arranging them in a sophisticated manner is to replicate complex organs such as the kidney and liver. The potential advantages are clear – waiting lists for donors would
be a thing of the past, as would organ rejection, because the 3D-printed variety would be made of the patient’s own cells. But there are huge complexities to be overcome.
One major challenge is to create a functioning circulatory system to keep organs functioning. The liver and kidney are full of tiny networks of blood vessels, and contain complicated structures that enable them to filter waste.
Work is underway all over the world to create the vascular systems that will be needed to keep organs viable. In September a team from Harvard used a 3D printer to make human tissue that included rudimentary blood vessels and, in 2013, researchers at Hangzhou
Dianzi University in China announced they had printed a small working “kidney” that lasted four months. But we don’t yet have the technology to replicate the incredible complexity of a complete liver or kidney.
“We’re still a very long way away,” notes Professor Melissa Little, of the University of Queensland’s Institute of Molecular Bioscience, which is working with a US company to 3D print small artificial kidneys for research. “We may find that it’s better to make large numbers of a particular kidney cell type and put them back into the kidney that’s still there in the patient. But we’re also interested in asking ‘how much can we scale this up?’”
People whose kidneys are failing could be saved from dialysis by the improvements a “kidney cell update” would create in their natural organ. THE FUTURE The push is on for 3D printing of micro- and even nanoscale complex structures that cannot be made with other manufacturing techniques – such as the lithium-ion battery the size of a grain of sand produced by Harvard University in 2013.
As the technology develops, so too do the possibilities. Using 3D printing at ultra- fine resolutions, researchers are making extraordinary leaps in their understanding of how cells work in a three-dimensional environment – and are gaining insights into how the human body behaves that just weren’t possible a few years ago.
“We’re now imagining the day where we can turn operating theatres into mini factories, where problems are dealt with as they arise,” says Professor Mark Cook, Chair of Medicine at the University of Melbourne and Professor and Director of Neurology at St Vincent’s Hospital. He likens the advent of 3D printing to that of the internet. As it becomes more commonplace and the cost falls (you can already buy your own basic 3D printer for a few hundred dollars), sophisticated medical technology will become available to people just about anywhere.
“The future isn’t limited by our imagination,” says Professor Choong.