3D printing — the future of medicine?

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I recently had a lengthy discussion about the potential viability, some day in the not too distant future, of a fully-functioning 3D-printed herd of elephants.

My fellow conspirators were a 16 year old kid, a surly Welshman and a Sri Lankan-Australian biochemistry student called Rahul, the driving force for sanity in the conversation. The setting was a suburban Melbourne train after an evening at the cricket. Much of the journey passed idly by. But amongst the jokes and questionable jibes, a seed of inspiration was planted in my head that has, of late, gestated into full-blown curiosity. Allow me to explain.

Rahul specialises in engineering solutions for medicine and has spent some time exploring the potential of 3d printing. At the time I must admit, to my shame, that very few details of his research stuck in my memory. His sincerity and passion for a fascinating subject were somewhat undermined by absurd claims and facetious questions. But amongst the silliness, I remember being distinctly impressed (don’t tell Rahul I said that!) by the cutting edge research my friend was actively engaging with.

Subsequent googling of my own has unlocked an area of fascinating discovery, uncovering both my ignorance of the amazing things we are already capable of in this field and the seemingly limitless potential of this technology. At the time, I jokingly suggested Rahul might one day be able to print a herd of elephants in honour of the herd his grandfather had once owned. Whilst this suggestion was, at the time, obviously absurd, I have since begun to question how far that absurdity stretches.

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The future we’re already living

Some of the things we can already do with 3D printers are astounding.

My prior knowledge of the technology was fairly limited. I’d heard of it, thought I knew roughly what it did and how it worked, and I knew someone in America had recently printed a gun with one. But I still believed it to be a fairly ungainly and lengthy process, an expensive and inefficient toy for big businesses and wealthy research labs to play with in their spare time. How wrong I was.

Most captivating to my mind is the field of bioprinting. 3D printing seemed wacky enough; 3D printing living organisms with cellular ink was a whole new level. The innovative thinking involved in adapting the print process for biological purposes is simply stunning.

Our initial foray into 3D printing in the early ‘80s was through a process called stereolithography, or SLA. High-intensity UV lasers are fired onto a vat of photopolymer resin which fuses the resin into the desired shape, tracing out each layer according to an electronically-produced design (or CAD) file. One layer done, the vat is lowered, a fresh layer of resin applied to the top and the process repeated. Eventually, the final layer is completed and a perfectly-printed replica of the file is produced.

In this way, extremely intricate and complex structures can be created on demand to exact specifications in a simple and efficient manner. As a result, each new design is as easy to print (in theory) as the last. Medically, this is extremely powerful. By adapting actual patient scans into printable CAD files, implants and prosthetics can be tailor-made to suit each patient’s specific needs at minimal extra cost or effort.

Examples of this in practice are plentiful. In early 2012, an 83-year old Belgian woman was the recipient of the world’s first 3D-printed jaw implant. Earlier this year in Australia, Dr Ralph Mobbs at Prince of Wales Hospital in Sydney successfully undertook a surgery of more than 15 hours to replace two highly-specialised vertebrae in a cancer patient’s neck. Not only was the titanium implant fully printed, Mobbs also replicated a number of exact models of the patient’s anatomy, allowing him to perfect the delicate and tricky procedure in a safe but accurate environment before undertaking it for real. Needless to say, this presents us with huge potential when it comes to streamlining medical processes and improving patient care.

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What about bioink?

However, SLA poses problems for bioprinting. Firing high-intensity lasers at living cells has never been a recipe for success. Nevertheless, innovators in the field have worked hard to adapt the traditional inkjet printer to allow a different type of 3D build that crucially has a benign effect on the cellular ink it uses. This technique, often called Thermal Inkjet Printing (or TIP), uses heat or mechanical compression to squeeze out tiny droplets of cellular ink onto a gel medium or sugar matrix, creating an extremely precise bottom-up build and limiting exposure of cellular material to harmful temperatures or radiation.

Through mastery of this technology, scientists across the globe have set to work researching the printing of almost every organ. Chinese scientists at Hanghou University of Science and Technology have developed the Regenovo, a specialised 3D bioprinter that has already successfully printed semi-transparent ears and kidneys. Across the pond, in November 2014 California-based research lab Organovo announced the commercial launch of their bioprinted liver samples, capable of remaining fully functional and stable for up to 40 days. By 2015, scientists at Henry Ford Innovation Institute had mastered 3D-printed replacement heart valves to exact specification for use in intricate surgical procedures.

These breakthroughs are hugely significant. Not only do they signal extremely promising progress towards the ultimate goal of fully-functioning printed human organs, they also represent significant advances in the field of medical research. One of medicine’s greatest setbacks has always been the difficulty of securing accurate, relevant and ethical pre-clinical drug trials, with animal testing offering similar but not exact host bodies and causing endless controversy. As printable, organ-specific human cell technology continues to advance, we inch ever closer towards a viable, affordable, repeatable and humane alternative.

Most excitingly, research in Princeton has taken 3D printing technology and used it to enhance human faculties beyond their natural capability. Combining biology with electronics, researchers have successfully managed to produce a fully-functioning human ear augmented with a small embedded coil of electronic antenna capable of detecting radio frequencies well beyond the regular capability of the human ear. We are still some years away from safely implementing this but the potential here is mind-blowing. It is increasingly realistic to believe that in just a few decades we might not only cure deafness but have the capacity to improve our hearing beyond our natural limitations. And if we can master the ear, why not the eye? The nose? The heart? Dare I even suggest the mind?

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So where does all this leave us?

Clearly, 3D printing is only limited by our powers of imagination and our current understanding of human biology. If humanity has proven anything in all its millennia of existence, it is that boundless imagination and scientific discovery have never been in short supply. What has been lacking, on numerous occasions, is sufficient ethical temperance. Understandably, we are easily lost in excitement at what we might be able to achieve and we forget to consider the potential consequences of our actions.

Domestic technological advances have made our lives incalculably more convenient. Smart phones, the internet, home computers and cars to name but a few have put the world at our fingertips. But they have also slowly degraded our willingness to read, think and even move for ourselves contributing to, amongst other things, massive global hikes in obesity. More dangerously, advancements in military technology have led the world to the brink of nuclear extinction on more than one occasion. With all the hype surrounding the great medical advancements 3D printing could facilitate, it is worth taking a step back and considering the implications of our unbound curiosity.

After all, if we don’t draw the lines in the sand, they will not draw themselves.

Whilst this field is extremely exciting and should (and will) continue to be pursued, we must always remain conscious of what we are and how we define ourselves. Printed organs for replacement solve a serious problem we currently face in society surrounding organ donation. But what does it mean to have the power to replace almost our entire body with printed material? How many replacements does it take before I’m no longer me? Similarly, enhancements such as Princeton’s ear research are tempting and could have huge benefits to our quality of life, but how much and how far can we ‘improve’ ourselves before too much of what we originally had is lost?

At its most extreme, should we ever finally unlock the secrets of the human brain and find ourselves capable of printing one that both works and lasts, could we really crack the fundamental mystery of creation? To draw back to my original conversation on that Melbourne train, is it really so far-fetched to imagine a world, many decades in the future, in which a living breathing 3D-printed elephant is no longer an absurd suggestion? It may not be so very long before we can produce every other biological piece of the puzzle bar the brain. With all of this in our armoury, what really are the limits of human capability?

The underlying question that will always surround ground-breaking revolutionising tech is this: even if we work out how to do it, to what extent should we actually put that knowledge to use? And if there is a line to be drawn, how do we stop ourselves from making mistakes we may yet come to regret?

I have no doubt that 3D printing will revolutionise our society and not just in the medical field. I just hope it doesn’t end up doing more harm than good.

Thanks to Luke Hargraves

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