An era of 3D-printed livers, kidneys and even hearts might arrive sooner than we think, a leading scientist says.
With the potential to answer a historic problem – an average 550 Kiwis are waiting for an organ or tissue transplant – the field is among the most exciting in science.
The concept of printing complex organs has been mooted for two decades, but recent breakthroughs have pushed it closer to reality.
"I absolutely see tissue engineering eventually removing the need for organ donors," said University of Auckland Professor Olaf Diegel.
"There are just too many advantages to it."
The field has its roots in the pioneering work of Dr Anthony Atatla, of the United States-based Wake Forest Institute for Regenerative Medicine, in the mid-1990s.
Numerous research institutes around the world now have some form of bio-printing programme, bringing together experts across medicine, biology, software, social sciences and mechanical and electronic engineering.
Diegel explained scientists are using two main approaches, both involving stem cells.
The first involves printing a sponge-like biodegradable polymer scaffold, on to which stem cells can be seeded and incubated.
As the cells develop, the polymer degrades at the same rate, meaning it completely dissolves by the time the cells have grown into an organ.
The second uses a gelatine-like goo called hydrogel, which is used to get the cells into the right shape as they are being printed.
As the cells are harvested directly from the patient, there is a much lower risk of their being rejected.
Most of the organs scientists have so far succeeded in printing are relatively simple ones, such as tracheas, heart valves and bladders.
Printed liver cells in petri dishes have also been created for drug testing, but scientists haven't yet reached the promised land of livers, pancreases and hearts.
"I think the biggest leap that is needed in this space, if we want to be able to print more complex organs, is to figure out how to do the vascular system," Diegel said.
In recent years, researchers have created mini-organs, known as "organoids", that contained many of the cell types and complex microarchitectures found in human organs, such as the kidney, liver, intestine and even the brain.
But most of the lab-grown organoids have lacked the intricate networks of tiny blood vessels needed to provide oxygen and nutrients, flush out metabolic waste and link different cell types.
In this space, there have been some promising developments.
This year, for instance, a team of US scientists created a 3D bioprinter that could print vessels less than a third of a millimetre wide in bio-compatible hydrogels.
Another team from Harvard University found a powerful new approach that enabled stem cell-derived kidney organoids to vascularise and mature further than they could before.
And, in another world-first, researchers at Israel's Tel Aviv University printed the world's first 3D vascularised engineered heart, using a patient's own cells and biological materials.
Diegel expects that, once scientists crack the vascular challenge, they'll cross the final hurdle.
Yet, he added, other barriers lie outside the lab.
An obvious one is price; another is whether people are ethically on board with the idea.
"There are issues like those raised in the movie The Island, in which the wealthy have clones of themselves on an island to use as spare parts should they have an accident," he said.
"Should you be allowed to print yourself organs that are 'better' than your original ones?
"Such ethical and social issues are just some of those we will need to tackle in parallel to the development of the science."
The future of 3D printing
Diegel, a multi-award-winning product design developer appointed under the previous Government's Entrepreneurial Universities programme, took up his role as the university's head of the Creative Design and Additive Manufacturing Laboratory this year.
His team are building what will, he hopes, change the way 3D printing, or additive manufacturing (AM), is used across industries.
AM uses a layering process rather than the conventional manufacturing process.
In the latter, a product is created by carving it out, or subtracting it, from a base material.
With AM, a 3D model of the original object is sent to a 3D printer, which prints many layers of liquid or powder to gradually build up a replica object.
It is a process that can produce parts that are infinitely more complex and lighter than possible with conventional manufacturing, while producing less waste.
AM has already had an impact in industries spanning from aerospace, automotives and construction to fashion and healthcare.
After leaving New Zealand in 2014, Diegel led the product development department and AM lab at Lund University in Sweden.
During his career, he has developed more than 100 new products for companies in New Zealand and internationally, including several home health monitoring, security, marine and lighting products.
He has also developed what's been described as the world's smallest refrigerator, to store insulin and other medicines.
He and his team at Lund also designed several AM-based prosthetics, including one for a 3-year-old girl who, as a result of a congenital condition, was born without her left arm.
What made it distinct from conventional prosthetics was its almost decorative sculptural aesthetic – more like an artwork than a conventional artificial limb.
"We first 3D-scanned the residual limb with a $300 scanner, which gave us a 3D model of the little girl's arm," he explained.
"We then married that with a computer-aided design [Cad] model of the prosthetic and then 'subtracted' the scanned arm form the Cad, which left a socket of the exact shape of the scanned limb."
This meant the prosthetic would fit the little girl perfectly.
"In fact, this project was undertaken more as a method to determine the recipe for prosthetic technicians to quickly and easily use these modern manufacturing technologies to make prosthetics faster - and therefore cheaper - and better fitting than with old technologies."
That and similar projects developed by his team at Lund resulted in the spinout company Anatomic Studios, which specialises in the design and manufacture of tailor-made prosthetic covers – designed to be worn as an item of fashion, a form of self-expression, rather than something to hide.
"Standard prosthetics don't look right – this is about making prosthetics beautiful rather than ugly."
Diegel and PhD students are now working with the Artificial Limb Society on artificial limbs for pets.
Rather than amputate a dog's entire limb if it suffers a crushed paw, for instance, they hope to make it possible to amputate only the damaged bit and replace with a prosthetic.
AM had opened up myriad possibilities, he said.
As a personal hobby, he has designed and made almost 75 guitars using AM – bespoke, elaborately designed instruments made to individual order, including a guitar that references rock band Guns & Roses, a steampunk guitar and many more.
One of his guitars, featuring a spiderweb motif, will be exhibited as part of the Wire and Wood exhibition, at the Museum of Design, Atlanta, this month.
Diegel sees potential in researching and advancing the materials that could be used in AM – such as cellulose from timber, "all those waste products that we now throw away".
He said most companies here see AM as a direct replacement technology for conventional manufacturing, which it isn't.
"For it to be cost-effective, parts must be redesigned to add value to the product, otherwise it can become a slow and expensive manufacturing technology.
"But if, for example, you can knock 60 per cent off the weight of your product, or make every product with a custom fit to the client, then you are adding enough value to make it a no-brainer.
"So we are spending a lot of time developing these new design techniques for AM, and then teaching them to companies so that they can use the technologies to add value to their businesses and better compete internationally."
In the short-term, he sees a big need to push the bounds of current software.
"We need better software that can make the technology more intelligent, and which can automatically redesign current manufacturing processes to take better advantage of additive manufacturing," he said.
"I think that's a potentially huge area of growth in New Zealand, because there's a world market for it."
• Professor Olaf Diegel will speak on 3D Printing the Future at the University of Auckland on Friday, July 12, as part of Winter Week on Campus. To register: https://www.publicprogrammes.ac.nz/events/winter-week/