November 23, 2020
3d printed organs

An Introduction to 3D Printed Organs and 3D Bioprinting

When people die, it’s not because their body shuts down, but because one part fails, which the body can’t survive without. People with heart or kidney failure need prompt organ transplants or they will die. That’s where 3D printed organs, such as 3D printed hearts, come in.

The average wait time for a transplant is 4 months for a heart, and 5 years for a kidney, according to Gift of Life. During this time people can become more ill and die, so the ability to print organs using 3D bioprinting would be invaluable. Replacing our organs once one fails would significantly extend human lifespans.

But how feasible are 3D printed organs?

This depends on the organ. In this piece we will go over four organs in various stages of R&D: 3D printed skin, 3D printed hearts, 3D printed hair, and 3D printed livers.

3D Printed Skin

Skin is the largest organ in the body. It protects your innards, holds you together, and regulates your body’s temperature. However, since skin doesn’t perform any complex chemical-sorting or blood-pumping activities the biological makeup of skin is one of the simplest of all our organs.

This is great news for scientists who wish to 3D print skin tissues. Companies such as L’Oréal are investing significant sums into R&D to discover ways to create 3D printed skin. Having the ability to do this is of great value to companies such as L’Oréal as they can test their sun and anti-aging creams on this skin without requiring living humans.

This in theory means that 3D printed skin would lead to better quality sun creams which would help reduce the prevalence of skin cancer. Additionally, apprentice tattoo artists have an easier source of fake skin to practice on, so maybe the quality of people’s ink will increase too.

3d printed organs l'oreal skin
L’Oréal are experimenting with 3D printed organs such as skin for their cosmetics.

3D printed skin replacing skin grafts

Skin grafts are currently the most common treatment method for burn victims. We are forever grateful to have skin grafts as a treatment option, though it is far from perfect. Negative effects include copious amounts of bleeding, possible infections, clear and obvious scarring, and a long recovery time.

Here’s where 3D printed skin comes in. Researchers at the Universidad Carlos III de Madrid in collaboration with BioDan have created a prototype for a 3D bioprinter that can print completely functional human skin. Since 3D printed skin can be created quickly and be applied straight onto the wound, wounds can recover significantly better than with skin grafts which take longer.

Research into 3D printed skin is not ready to be brought into treatments yet however. The treatment is not mature and reliable enough, though results are very encouraging. It is very likely that 3D printed skin treatments will be widely available within the next 5 years.

3d printed organs skin
R&D into 3D printed skin.

3D Printed Heart

Around 3,000 people in the USA are waiting for a heart transplant on any given day. Since about 2,000 hearts are available each year, waiting times can stretch into the months, and even years.

Contrary to what you’re probably imagining, the heart is one of the most biologically simple organs in the body. This means it would be one of the easiest 3D printed organs to create and transplant. Since the heart is so important, this is pretty handy, right?

Current thinking suggests the best way of creating a 3D printed heart is through bioprinting cell ‘scaffolds.’ Rather than 3D printing cells layer-by-layer, these biodegradeable scaffolds provide structural support for cells, directing them to where they should be. Then when the cells into fully mature, finished 3D printed heart structure, the scaffold can be broken down and removed.

This has already been shown to work on a micro scale with a patch of working heart tissue. The 3D printed heart tissue was successfully used to repair a damaged mouse heart.

We’ve written a separate feature story on 3D printed hearts.

3d printed organs heart replica
A 3D printed heart for medical students to practice on before real surgeries.

There are however difficulties making this work. If there weren’t, we’d all have 3D printed organs and have significantly extended our lifespans. Hearts are made up of very very very small structures in capillaries which no bioprinter available can replicate. They are simply too small. NASA has a $500,000 bounty for anybody who manages it – want to have a try?

How close are we to creating a 3D printed heart?

In July 2017, ETH Zurich, led by Nicholas Cohrs, a doctoral student, created the first 3D printed heart made up entirely of soft silicone material. Its pumping mechanism works very much like a real human heart, and was printed in one large structure. This means no parts need to be pieced together except the input and output parts where blood goes in and out.

This artificial 3D printed heart managed to last around 30 minutes/a few thousand beats before the materials couldn’t handle the strain and broke down. This represents good progress, but shows how far we are from creating a reliable alternative to taking hearts from dead people and transplanting them. A conservative estimate before 3D printed hearts become achievable is 30-50 years at current progress levels.

3d printed organs heart eth zurich
ETH Zurich’s 3D printed heart is a 3D printed organ which lasted for 30-45 minutes.

3D Printed Hair

What’s the number one cause of people not buying shampoo? Yup, baldness. Therefore, it is of supreme importance to companies such as L’Oréal to restore hair to those unlucky men who have been relegated to sporting the Bruce Willis look for eternity.

L’Oréal are working with Poeitis, a 3D bioprinting company, to try and create synthetic hair follicles using 3D printing. Poeitis have developed a 3D printer which uses a similar technique to a two-dimensional inkjet printer that deposits cells instead ink. Poeitis’ machine deposits cells, one by one, at the astonishing speed of 10,000 per second. These microdrops of cells then form 3D structures as they layer on top of each other.

Poeitis call this 4D printing. As you know, the fourth dimension is time, which Poeitis use to justify their claim as the cells are printed one by one, encompassing the fourth dimension. This enables them to guide the cells and their environment “between the cells and their environment until they produce the biological functions we are looking for.”

Having started in 2016, the French company expects it will take 3 years to adapt the process. If hair follicles can be printed and then transplanted onto human heads, this could be the miracle cure to baldness.

3d printed organs hair
3D printed hair and hair follicles are being tested in various R&D labs.

3D Printed Liver

The liver is arguably the most important organ in the body. It produces proteins which are crucial to blood clotting, breaks down fats, and filters out toxins whenever you go on a heavy night out.

Dr Shaochen Chen at the University of California San Diego announced developments of a new 3D printed liver tissue which mimics the structure and function of a real human liver back in 2016. To create this tissue, stem cells are taken from the patient’s skin and combined with two other cell types before being changed into liver cells. Stem cells are special in that they can change into other cell types and divide to produce more of these. This makes them very valuable for research and treatments.

The 3D printed liver tissues were then deposited into 3 x 3 mm squares, 200 microns thick. The squares were cultured in vitro for 3 weeks as they turned into tissues. Following testing, the 3D printed liver tissue was found to be able to maintain the key functions of the liver for a longer time than existing liver models could. This is encouraging for those who foresee 3D printed organs becoming widespread in the future.

3d printed organs liver
An example of a recent 3D printed liver model.

Organovo: 3D Printed Livers in Mice

In 2017, 3D bioprinting company Organovo tested their exVive 3D printed tissues to prove just how effective they were. Testing was done by implanting patches of their 3D printed liver tissue onto mice livers. The tests found this to be a valid treatment that could be used to treat alpha 1-antitrypsin.

Alpha 1-antitrypsin is a disease which affects the liver when the body makes insufficient amounts of a protein (research). This leaves the patient more vulnerable to other conditions such as emphysema and cirrhosis.

Sixty days after being implanted, the tissues showed sustained functionality and engraftment. This is a significant improvement on previous research on 3D printed liver tissue which only sustained functionality for 28 days. Moreover, a pathological evaluation revealed that the mice who’d had the tissue implanted had healthier livers than a control group that received no treatment.

These results are very encouraging. Organovo plans to submit its 3D printed liver tissue for FDA approval in 2020. This gives them 18 months to perfect and optimize the final design before submission.

Livers are however far more complicated than organs such as the heart. The liver has many different functions which makes it an enormously complex organ biologically which would be very difficult to 3D print. If our estimation on 3D printed hearts is 30-50 years, 3D printed organs such as the liver would be longer. However, 3D printing is an exponential technology and with how weird things are likely to get in the future, it is foolish to predict anything longer than 50 years. Some people think the Singularity will occur by 2045, so who knows if a biological, 3D printed organ breakthrough will occur well before then.

3d printed organs process
Source: FT. The 3D printed organ process.

3D Printed Organs: Conclusion

Overall, we’re getting to become accomplished at creating small 3D printed tissues. We are therefore likely to have found a reliable way to create 3D printed skin in the very near future. However, with organs such as hearts, livers, and kidneys, the microscopic size of capillaries make them impossible to print at the moment.

We may not be far from a society who possess 3D printed organs and go about their day as if this is normal. Scientific breakthroughs occur all the time, and as 3D printing improves and becomes more accurate over smaller distances, perhaps we can solve the organ shortage with 3D printed organs.