3D printing and medicine

3D printing can offer great benefits in medicine, but it also raises a number of ethical questions as the technology develops, says Susan Dodds.

Three-dimensional printing technologies have the genuine potential to improve medical treatments for conditions ranging from bone cancer and arthritis to glaucoma and hearing loss.

Already 3D bioprinting allows orthopaedic surgeons to print artificial bone from a scan of the patient, printing existing surgical materials to precisely the right shape to replace missing or damaged bone. For example, the technique has been recently used to create skull implants for people with head trauma and a titanium heel (pictured right) to replace heel bone that had been eaten away by cancer.

In the future, 3D printing technologies may be used together with advances in stem cell research to print living bone cells from patients’ own cells or functioning organs for transplant (such as kidneys or hearts).

3D bioprinting is one of the latest developments in ‘personalised medicine’.

The technology could enable doctors to tailor treatments to individual patients, rather than developing a treatment that works well for most patients with that condition.

But 3D bioprinting also raises a number of ethical questions that will need to be considered as these technologies develop.

Three ethical issues that are raised are: justice in access to health care, testing for safety and efficacy, and whether these technologies should be used to enhance the capacity of individuals beyond what is ‘normal’ for humans.

Justice and access

One major concern about the development of personalised medicine is the cost of treatments. Until recently it has been thought that advances in personalised medicine go hand-in-hand with increasing disparities in health between rich and poor. Should these treatments only be available to those who can pay the additional cost? If so, then those patients who lack financial resources may not receive effective treatments that others can access for a range of serious conditions.

Personalised medicine is most closely associated with research in genomics and stem cell therapies.

Advantages of personalising medicine are most obvious in cases where the condition affects patients in very different ways and standardised treatments offer imperfect benefits. For example, conditions affecting the growing bones of children are among those where personalising treatments, if these can be adapted to the rapidly changing bodies of children, can make a very big difference in the child’s comfort and capacity to participate in ordinary childhood activities and play.

Until recently, the cost and time required to provide a series of customised prostheses of different sizes for a child who has lost a leg to cancer, for example, has been prohibitive for many patients. 3D printing will bring down the time and cost of customising and producing prosthetic legs. In cases like that of Ben Chandler, printers can also be used for implants, which might avoid the need to amputate the original limb, even where significant bone loss has occurred.

The capacity to use 3D printing technology to substantially reduce the cost of prosthetics, or orthopaedic surgery to restore lost bone structures, means that this area of personalised medicine can avoid the criticism that personalised medicine inevitably increases the cost of health care and puts effective personalised treatments out of the reach of many patients.

Will 3D printing treatments be safe?

A second ethical concern about any new treatment, including the use of 3D printing, is how we can test that the treatment is safe and effective before it is offered as a clinical treatment.

In the case of 3D printing to replace bone, the materials used — for example titanium — are those already used for orthopaedic surgery, and have been tested for safety over a long period and with many patients, so it is unlikely that there are new risks from the materials.

In the future, 3D printing may be used in combination with stem cell derived cell lines.

This could lead to the development of printed functioning organs that can replace a patient’s damaged organ, but without the risk or rejection associated with donor organs, because it uses that patient’s own cells.

How can we know in advance that these treatments are safe? Unlike the case of developing a new drug, a stem cell therapy can’t be tested on a sizable number of healthy people prior to being tested on patients and then, finally, being made available as a standard treatment. The point of using a patient’s own stem cells is to tailor the treatment quite specifically to that patient, and not to develop a treatment that can be tested on anybody else.

Researchers combining 3D printing with personalised stem cell therapies beyond the experimental stage will need to develop new models for testing their treatments for safety and effectiveness.

Regulatory bodies that give approval for new treatments, such as Australia’s Therapeutic Goods Administration (TGA), will also need to establish new standards of testing for regulatory approval before these treatments can become readily available.

This means that even if researchers were ready to print a functioning prosthetic organ, it will be quite some time before patients with kidney disease should expect to be offered a 3D printed prosthetic kidney that uses their stem cells as a routine treatment.

Human enhancement

The third issue is whether or not we should use 3D printing for human enhancement.

If the technology can be used to develop replacement organs and bones, couldn’t it also be used to develop human capacities beyond what is normal for human beings?

For example, should we consider replacing our existing bones with artificial ones that are stronger and more flexible, less likely to break; or improving muscle tissue so that it is more resilient and less likely to become fatigued, or implanting new lungs that oxygenate blood more efficiently, even in a more polluted environment?

The debate about human enhancement is familiar to the context of elite sport where athletes have sought to use medical technology to extend their speed, strength or endurance beyond what is ‘natural’, or what they are able to achieve without drugs or supplements. In that context use of performance enhancing drugs is considered to cheat other athletes, unbalancing the level playing field.

In the case of 3D bioprinting enhancement of human capacities could be associated with the military use of the technology and the idea that it would be an advantage if our soldiers were less susceptible to being wounded, fatigued or harmed in battle.

While it is clear that it would be preferable for military personnel to be less vulnerable to physical harm, the history of military technology suggests that 3D printing could lead to a new kind of arms race. Increasing the defences that soldiers have in the face of battle would lead to increasing the destructive power of weapons to overcome those defences. And in so doing, increasing the harm to which civilians are exposed.

In this way 3D printing may open up a new gap in the vulnerabilities of “enhanced” combatants and civilians, at a time when the traditional moral rules concerning warfare and legitimate targets is muddied by terrorism and insurgency.

These three points might just be scratching the surface of new, deeper ethical and social issues that will emerge as the technology progresses.

The future of 3D bioprinting applications holds the promise of better treatment while challenging communities to address emerging ethical questions.