3D printing is often referred to by the term additive manufacturing, because of the way objects are printed (layer by layer). The term rapid prototyping is also used since, as the name says, it is a means of quickly producing a three-dimensional object. Invented in the 1980s and originally called stereolithograpy, the ever expanding field of 3D printing offers much more than just a way of rapidely achieving three-dimensional mock-ups. As it applies to life science, 3D bioprinting is the process of creating complex structures that mimic original tissues and organs using 3D-printing technologies, where cell function and viability are preserved within the printed construct.

In its simplest (and earliest) health care applications, 3D printers make three-dimensional models of organs to be used before and during surgeries, for planning and execution. Prosthetics can also be 3D-printed, allowing customization much more easily. An English firm is even offering a 3D-printed wheelchair, which it says can be taylored to fit the individual needs of a wide range of disabilities and lifestyles.

Another very promising area of application is personalized pharmacy, where pills are 3D-printed to the specifications of the patient’s pharmacist like e.g. drug release profile, dosage, even color and geometry. Errors in medication accounting for thousands of deaths each year in the US alone, such a way of producing patient-specific medication has the potential of significantly reduding this number.

All those applications, as useful and interesting as they are, are not bioprinting per se, since none involve the production of biological contructs. Bioprinting has its own specific challenges. To name but a few, printing devices and methodologies have to take into account the sensitivity of living cells, the biomaterial being printed (the bioink) has to first be available in a printable state―obviously. Regulatory issues need also be addressed. These additional complexities can and are being overcome, and are offset by the immense advantages 3D-bioprinting promises.

Clinical trials and drug testing can be long, complicated and costly processes. Using 3D-printed human or human-like tissues can greatly simplify these endeavors. No (or less) cultural or ethical issues are involved, and no subjects need be recruited to undergo studies

Body implants, made of foreign material, can be toxic and cause rejection, whereas 3D-bioprinting provides organic implants which, as with 3D-printed prosthetics, can be shaped individually and with precision, based on MRI and CT scans images.

Regenerative medicine is another obvious area of application. Rejection rates are lower and success of surgery is higher when tissue built from the patient’s cells himself are used to 3D-bioprint the implanted tissue. Together with the lower cost of 3D-printing the tissue itself, the overall cost to the healthcare system can be greatly reduced. Skin, bone, cartilage, teeth, even complete organs like a heart can be 3D-printed. Yet another advantage is that the possibility of “manufacturing” tissues and organs helps alleviate the difficulty of finding compatible donors for transplants. 22 people die each day while waiting for a transplant in the US.

As very briefly described, 3D-bioprinting promises to disrupt health care in many and yet unknown ways. But the next step is already being taken : 4D-bioprinting, where the 4th dimension is transformation. It is the 3D-printing of smart, stimuli-responsive biomaterials to create constructs that emulate the dynamics processes of biological tissues and organs. Imagine for instance that, instead of having to 3D-print a skin graft for a burn victim, with all the entailed complexity, you could 4D-print a basic skin graft that would, once implanted on the patient, vascularize itself, develop all nerve endings, take on the patients complexion, and even grow hair if on the head ? In a way, 4D-bioprinting is to medicine what AI is to computer science.

Are we on our way to making 4D-bioprinting synonymous with procreation ?

As always, comments, questions, feedback are welcome.

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