The next frontier of 3D printing: your bones

Jeanne Calment led a pretty normal life. She smoked in moderation. She took light exercise. She remembered seeing the Eiffel Tower built in 1887. She sold pencils to Van Gogh. But she got into the Guinness Book of Records because, when she died in 1997, she was 122 years old, officially the world's oldest person. She attributed her longevity to a diet heavy on olive oil, port wine and chocolate.

But scientists do not expect her to keep her record for long. In fact, they think that many of us will live well past 100, and the secret will be the ability to replace old body parts with new.

How will we do this? By simply printing organs with a 3D printer.

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We are already printing body parts

You will probably already be aware of 3D printing. Instead of printing a two dimensional image, as we do at home on a paper printer, 3D printing machines print one layer upon another until they have built up a three-dimensional object. You can watch a 3D printer in action here.

The advantage of 3D printers is that we can produce remarkably complex objects. They are already commonly used to build everything from hearing aids to aircraft components. In fact, the market for 3D printers grew 29% from 2011 to $2.2bn worldwide last year, according to Wohlers Associates.

How long before we can print hips, knees and vital organs? Well, it might surprise you to know that we are already using 3D printers to make body parts. Take the case of one Kaiba Gionfriddo.

The days after the birth of Kaiba were terrifying for his parents, Bryan and April. Kaiba would repeatedly stop breathing and turn blue. Time after time he struggled through, but still the doctors warned that he might not even leave the hospital alive.

Dr Glenn Green of the University of Michigan had other ideas. He believed that a revolutionary new technology could save Kaiba's life. And he was right.

Kaiba was suffering from a rare condition called tracheobronchomalacia. A collapsed airway was blocking his efforts to breathe. The solution was to make a tubular splint to fit around the airway and hold it open. For that Dr Green first made a CT scan of the airway to get its exact measurements and then made the splint. And here is the revolutionary bit: the splint, made of a biocompatible polymer, was laid down to exact specifications by a 3D printer.

This revolutionary technology saved Kaiba's life. Thanks to the splint and Dr Green, Kaiba is now breathing normally to his parents' huge relief.

And although Kaiba Gionfriddo is the first child to receive a 3D-printed airway splint, he is not the first human to receive a body part made in this way.

Last year, for example, doctors in the Netherlands fitted an 83-year-old woman with a new jaw after her own had been destroyed by a chronic bone infection. Again, the first step was to create a computer image of the new jaw. This then instructed the 3D printer to create the jaw, by laying down titanium powder that was fused together by a laser.

The jaw had articulated joints and cavities to promote muscle attachment and grooves to direct the regrowth of nerves and veins. Finally it was given a bio-ceramic coating so that it would not be rejected by surrounding tissue.

It was a remarkable feat of engineering. And the scale of the opportunity for biotech investors must be obvious. If we can print jaws and airway splints, what more could we do?

This is a question I've been asking myself since I watched surgeon Anthony Atala talk about his work in engineering body parts in 2011. It was a stunning video you can watch the video here. And since then, I've watched as this field of regenerative medicine has become one of the most exciting investment stories of my lifetime.

Regenerative medicine finally comes of age

Regenerative medicine is one of the most promising areas of biotechnology. And I spend quite a bit of my time these days talking to scientists and executives in this field to keep up the pace of development.

The basic principle of regenerative medicine is to harness the body's natural powers of regeneration to repair or replace damaged tissue.

The cells in our body are constantly dividing, as new ones replace those that die. Our bones completely renew themselves every seven to ten years, while our skin takes just one week. As we get older this cycle of renewal gradually slows down. If we could decelerate this trend or simply replace the parts that have worn out, then we could live much longer.

This is the promise of regenerative medicine. And I have a number of stocks in my Red Hot Biotech Alert portfolio that are poised to benefit.

I can't give away those stocks here. But just consider the example of San Diego-based Organovo (Nasdaq: ONVO) a company that is printing body parts cell by cell and without the need for a scaffold.

This company is making remarkable advances. And at its last balance sheet date, Organovo had shareholders' equity of just $6.9m and absolutely no revenue from the sale of products. Despite this, the company is valued at $425m, a sure sign of enthusiasm for the concept of printed body parts.

We can start with teeth, hips and knees

Organovo's main product is the NovoGen MMX Bioprinter, which can manufacture three dimensional tissue from live biological cells. Once deposited, the cells coalesce in the same way that two drops of water join together, and then start to relate to each other, sending out signals and forming structures.

In this way, functional human tissue can be developed in the laboratory. This has fanned extravagant hopes. How soon can it be before we are building fully functioning organs, like kidneys and hearts, made to measure by CAD/CAM software, laid down by a 3D printer, all ready to be popped in to the body?

For more complicated and essential organs, the answer is more likely to be decades than years. But we are already making simple body parts. For years we have been fitting replacement hips and knees made initially from metal, then ceramics and later polyethylene. 3D printers have been used to make bone grafts from ceramic, dental crowns from porcelain and hearing aids from acrylic. Because of its relatively simple structure, skin has also been a primary target for regenerative medicine, and a number of products are already on the market.

Skin and bone can be repaired without causing collateral damage, and any complications can be addressed relatively easily. Kidneys and livers are far more complicated. They are made of many different cell types and need a supply of blood to function efficiently. Hearts need an electrical system to tell them when to beat. However, exciting experiments have been conducted.

By seeding a prepared scaffold with cells, rat hearts have been created in a laboratory and were seen to expand and contract. Artificial ears have been made by building a mould on a 3D printer and then filling this with collagen derived from rat tails and cartilage cells extracted from cows' ears. Bladders have been made by growing muscle and bladder in a Petri dish. They have been successfully implanted into patients.

There are some even more ambitious notions out there. Researchers at Princeton University have created an ear from hydrogel and bovine cells which incorporates a coiled antenna made from silver nanoparticles. This bionic ear could pick up radio frequencies beyond the range of normal human hearing. Bioengineers might one day incorporate sensors into other tissues for instance creating a bionic knee joint that can monitor strain.

Others envisage that body parts need not be made in the laboratory and then implanted. The cells could simply be printed directly onto whichever body part was in need of repair, be it on the surface of the body or deep within it. While we are today starting with relatively simple skin grafts, blood vessels, nerve grafts and patches for damaged hearts, the dream is to create new body parts and end the reliance upon donor organs.

Clinical testing on 3D-printed liver tissue

But this is not the only promise of 3D printing. Organovo expects to generate its first commercial revenue from the sale of fabricated tissue for drug testing.

Today, new drugs are tested either upon two dimensional cell lines cultured in the laboratory, or upon animals. Neither of these gives a particularly accurate prognosis, one reason why so many drugs come through early stage trials before failing when given to humans.

Organovo believes that three-dimensional human tissue samples could be a better medium for testing new drugs, and hopes to begin selling liver tissue next year. Liver toxicity is the most common reason for a drug to be pulled from clinical trials, and this could be more accurately tested on three-dimensional samples of liver tissue.

3D printing is starting to make a contribution to medicine, but we should not get too carried away at this early stage. There is still a lot more work to be done and some serious ethical questions that need answering. I recently saw a product called Shape of An Angel' a product of dubious taste offered by the Japanese firm Fasotec to expectant parents. It is a 3D-printed model of the foetus!

In the coming years, I think we will see 3D printing playing a more useful service, and this is certainly an area to keep an eye on.