Will Harvie
Imagine this future scenario: A surgeon has removed a cancer that’s eaten into a patient’s bone. The procedure has left a ‘‘void’’ or hole in the bone.
The surgeon then implants bone tissue created from the patient’s own cells and some regenerative scaffolding materials.
They have been layered and shaped by three-dimensional bioprinting to match the anatomical shape of the void.
In the right circumstances, the scaffolding materials biodegrade as the bone cells grow to fill the hole.
‘‘Maybe in a year’s time, your knee or hip would be like it had never been damaged,’’ says Dr Tim Woodfield, principal investigator at the University of Otago’s Christchurch Regenerative Medicine and Tissue Engineering lab. ‘‘You would have beautiful new tissue that would have grown into the old tissue and the scaffolding would have biodegraded.’’
It might be 10-15 years away but that’s the promise of 3-D printing of human cells.
It’s one aspect of a field called regenerative medicine. ‘‘It’s the future of orthopaedic surgery,’’ says Woodfield.
He can imagine other scenarios where 3-D bio-printing might help with orthopaedics. Full knee and hip replacements are now common but the devices wear out after 10-15 years and need replacement. Doctors are also reluctant to undertake full transplants when the patients are in their 40s or 50s.
It might be possible to delay those full transplants with a less invasive and cheaper 3-D implant that could take a patient into their 60s or 70s, he says.
Orthopaedic 3-D printing is an immensely complex field and research is still embryonic.
Dozens of labs around the world are working on aspects and serious money beckons for those who secure intellectual property
It won’t be soon but eventually New Zealand surgeons will custom 3-D print bones and cartilage for implanting. reports.
rights. Woodfield is careful not to oversell the accomplishments of his lab.
Rather his lab is contributing to the slow accumulation of knowledge that might some day result in filling bone voids and related procedures. It’s a bit like 3-D printing itself, a slow and deliberate accretion of layers that add up to something practical.
When 3-D bio-printing emerged earlier this decade, there was talk of constructing whole organs for transplant – a liver, for example.
‘‘I’ve always been reasonably sceptical that we’d ever get to the point ... because of the complexity,’’ Woodfield says.
‘‘What we’re getting good at now is printing small pieces of tissue,’’ Woodfield says. In orthopaedics, that means printing small, complex pieces of bone and cartilage.
Getting this far required important developments. First researchers needed 3-D printers that were friendly to living cells.
They had to operate at body temperatures instead of hot and not be toxic to cells.
Commercial bio-printing machines are now available, he says. ‘‘The major breakthroughs and developments aren’t coming up with fancier printers.’’
Designing suitable materials to use in 3-D bio-printing has needed work, however.
Tissues in our body are mostly water. They would sort of ‘‘puddle’’ without a supportive scaffolding around them.
The trick, then, is supplying a supportive ‘‘watery’’ environment in which the cells can happily exist and that can be 3-D printed.
Woodfield variously calls this a construct, a matrix or a bio-ink.
In creating bio-inks, many research groups around the world use gelatin, which provides the necessary 3-D scaffolding while still being malleable (like living tissue) and not too stiff.
In some cases, these substances are ‘‘set’’ using ultra-violet light in a way similar to how a dentist cures a modern filling with light.
This presents several challenges, not least that UV light can damage cells – UV is, after all, the main culprit in sunburn.
Dr Khoon Lim and Dr Gabriella Brown from Woodfield’s lab investigated replacing UV light with visible light to cure a bio-ink.
It turned out this required ‘‘some clever chemistry’’ but it