3D printing for surgery
At a restaurant in Youngstown, Ohio, a couple are enjoying one of their first meals out since having a baby six weeks earlier. Suddenly their newborn boy, tucked up in a portable cot next to them, turns blue. The father discovers he’s stopped breathing, plonks him on top of the table and frantically begins delivering CPR.
The couple, Bryan and April Gionfriddo, manage to get their baby, Kaiba, to a nearby hospital, which is the start of a nailbiting few weeks for the pair. Kaiba received CPR every day, with his mother fearing he may not leave the hospital alive.
Kaiba had a rare, life-threatening birth defect known as bronchial malacia, where the respiratory tract – which takes air into the lungs – is floppy and collapses in on itself.
“It’s been a problem having these kids die for a long time,” says Glenn Green, a paediatric otolaryngologist at the University of Michigan. “I’d been looking for an answer for a while.”
Green had a last-ditch plan to save Kaiba’s life – 3D printing.
“Kaiba was right on the edge [of dying], but I thought, this is something that could actually work,” says Green. “It was very exciting but also very nerve-racking. There were a lot of unknowns.”
3D printing was first pioneered in the 1980s when it was known as Earlier Additive Manufacturing. It involves building up an object layer by layer, says Professor Gordon Wallace, of the Australian Institute for Innovative Materials at the University of Wollongong.
It works by inputting a 3D image into a computer program known as a “slicer”. This turns the image into a code that gets sent to the printer as commands. The printer uses whatever “ink” is provided – including metals, ceramics and polymers – to print thin cross-sections of the object in layers, one upon the other, to create the physical object.
It has particularly exciting uses in surgery. For more than a decade, the technology has allowed imaging technicians to print personalised ceramic models of the human body directly from a CT scan or ultrasound.
One patient this benefited was Ade De Adiwadi, a 45-year-old bank manager with young children. One day Ade’s bank in Lagos, Nigeria, was held up, during which he was shot repeatedly with an AK-47. The intruders hit Ade six times at close range, causing him to lose all of his right jaw, his lower lip, teeth and half his tongue.
Doctors in Nigeria took an MRI scan which was sent to Cavendish Imaging in London’s Marylebone. There the team used the scan to print a 3D model of Ade’s remaining jawbone. They used modelling clay to mould the missing parts of jaw, from which they created a metal plate to be screwed into Ade’s existing bone. After multiple operations – one of which lasted 19 hours – Ade had a new face.
“On waking up, I discovered I had my mouth back again. It was a lost hope that was restored,” Ade says. “Today, my voice is back as normal.”
In this manner, 3D printing allows surgeries to be customised to the patients.
“When I go into the operating theatre, I know exactly how much bone I need to put in place and I’ve already decided where I want to take it from, by making models of the donor site,” says London-based maxillofacial surgeon Iain Hutchison, who treated Ade.
And the capabilities of 3D printing go beyond the creation of customised models. Medical teams have been able to prefabricate other parts of the body to be directly implanted, such as chins, heels and teeth.
“We make them in titanium that can be implanted straight into the body,” says Veronique Sauret-Jackson of Cavendish Imaging.
Imaging technicians have also been able to make hips for hip replacements and wearable prosthetics.
Orthopaedic surgeon Craig Gerrand, of the Newcastle upon Tyne Hospitals NHS Foundation Trust, implanted a 3D printed pelvis into a man in his 60s. The patient, who’d had a rare type of bone cancer, needed his entire hemipelvis removed. It was a tough operation since the implantation was large, weight-bearing and in an area with a high complication rate for infection. But the surgery prevented the patient from having a hanging hip and one leg shorter than the other.
Five years on, Gerrand says, “At this relatively long follow-up, the implant remains in situ and the cancer has not returned, thankfully.”
In order to treat baby Kaiba, Green also printed an implant, specifically a tube to replace Kaiba’s bronchus and take air into the lungs. The difference here was that the implant would break down and dissolve with time.
It was very much an experimental procedure, says Green. Using biological materials made from petroleum and a CT scan of Kaiba’s airways, the bronchial splint was perfectly custom-built. The flexible plastic material, known as polycaprolactone or PCL, dissolves after three years. In this case, it allowed Kaiba’s bronchus time to grow strong before the splint dissolved and disappeared without the need for surgery to remove it.
This method has been dubbed “4D printing”, because the material adapts with time as well. Since Kaiba’s operation proved a success, it has been used in four other children who’ve ranged in age from three months to 14 years old. One of these was Garrett Peterson.
Garrett was born with massive heart defects, and was whisked straight into an intensive care unit where he spent the first 19 months of his life hooked up to a ventilator. His heart had four major problems, including missing a pulmonary valve and having pulmonary arteries three times the size they should be.
His father, Jake, recalls: “He’d have blue spells where he couldn’t breathe at all. He’d turn blue, purple, black, and almost pass out. They’d have to do CPR every time. It was heartbreaking.”
After Garrett suffered a very bad virus, doctors suggested that removing his left lung might be his only hope of survival. At this point Jake came across an article about Kaiba and his 3D-printed bronchus. They got in contact with Dr Green, who arranged for the still rare procedure. Eight hours of open-heart surgery were required to implant two airway splints in Garrett. His mother, Natalie, reports: “Two-and-a-half months after the operation, he’d gone from super critical care in an ICU to the lowest setting you can go to on a home ventilator.”
Gordon Wallace at the University of Wollongong says the cases of Kaiba and Garrett reflect the tip of the iceberg in terms of what’s possible. His particular interest is in printing with biological materials. Research laboratories around the world are working to make biomaterials that encourage human organs and body parts to regenerate, including bones, nerves and muscles.
“It’s about persuading natural biological processes to work with cells,” says Wallace.
His research team is using what are known as growth factors, which are naturally occurring substances – often proteins – that encourage cells to grow.
“We bioprint temporary structures that instruct cells how to grow – and make them do so quickly – before dissolving when their job is done.”
One material they’re experimenting with is seaweed, which they source from a farm in Nowra. The team combines extracts from the seaweed with fat cells to make an ink with which to print.
“It’s sort of the consistency of hand-sanitiser gel,” Wallace says. In the correct environment, the printed material can prompt cells to grow and turn into cartilage.
Wallace’s team is trialling implants of this cartilage in animals. “If it’s successful, within a handful of years we’ll have cartilage scaffolds for humans,” says Wallace. “We’re also printing small groups of cells in layered structures that can start to mimic organs.”
These latter experiments include neuronal cells: “It’s like a brain on the bench,” Wallace says.
The team uses these cells to study how mental diseases, such as schizophrenia and epilepsy, emerge. They can also test therapies on these structures.
Other researchers are using 3D printing principles to create layers of cells for skin regeneration, while researchers in Toronto have developed a “tissue-velcro” that can bind individual layers of heart cells on top of each other in a stack. When fully functional, it will act like a dissolvable stitch, bonding damaged heart tissues together before the polymer disintegrates.
The findings have revolutionised the world of stem cells, helping to eliminate much of the controversy surrounding the use of embryonic stem cells.
“Our work uses the patient’s own stem cells that in the right environment can turn into cartilage. So you’re not dealing with getting stem cells from other people,” Wallace says.
The goal is to one day use this technology to print complete human organs, wiping out the need for donors. Wallace believes this will be achieved but he’s unsure on the time frame.
“Five years ago we wouldn’t have thought that we’d be printing stem cells, so it’s hard to predict just how far or near [printing organs] is.”
In the meantime, 3D printing is already saving lives.
Almost two years after his operation, Garrett has recently gone off his ventilator and is catching up developmentally to his peers.
“He’s doing extremely well. He rolls around and holds his head up,” says his father, Jake.
“We’re so grateful.”
This article was first published in the print edition of The Saturday Paper on Feb 13, 2016 as "Body building". Subscribe here.