Transplant lists are long and many patients die waiting for an organ. The time may be closer than anyone imagines for printing living human replacement organs. Scientists have been working on the 3D printing of living organs so that anyone that needs a transplant can have one without long waiting lines.
3D printing is not a new technology but it is being used in new and exciting ways by the medical industry. There have already been several successful experiments conducted to grow bone, skin, stem cells and other tissue. Organs are a bit trickier because of the blood vessels that are involved in their function. But scientists the world over have been working on using 3D printing to create all of the intricate cell networks needed to grow hearts, livers, kidneys, bladders, lungs, pancreases and other organs.
In 2011 scientists at the Fraunhofer Institute in Germany had a breakthrough and were able to successfully use 3D printing to grow blood vessels. This technique known as multiphoton polymerisation has moved the research exponentially.
The researchers, in general, have found that the flatter the 3D bioprinting the better the results. In other words skin is relatively easy to create using bioprinting because it has mostly flat layers of cells. The more complex the structure, the harder it is to replicate because there are more types of cells involved and in varying shapes, sizes and materials.
Human organs pose a different level of difficulty for two reasons. The organ’s capillaries are tubular and hollow and made up of different cell types which make them harder to recreate accurately. In addition, many of the organs have hollow features and contain multiple cell types as well.
Two Schools of Thought
There are two different schools of thought on the best way to create new organs using 3D printing. One school of thought is that building an organ using a scaffolding (synthetic polymers to hydrogels) that is created by the 3D printer and is “seeded” with human stem cells that are harvested from the patient’s bone marrow is the most viable.
The other school of thought is one that thinks that creating scaffoldings are not necessary. These scientists believe that human stem cells can become the “ink” in the printer cartridge and can be used to create the organ without a need for the scaffolding.
Each school of thought is presented with different problems to overcome. The first, with the scaffolding, has to be able to find a scaffolding material that will dissolve easily without causing damage to the living cells.
The second school of thought believes that they can depend on cells’ natural ability to organize without the scaffolding material in the 3D printer. These scientists have to find a way to reinforce the delicate cells without scaffoldings.
Starting Out Small
Many labs, no matter the school of thought, have realized some success working on a very small scale. These labs have been able to grow organs that are microns large. Researchers at the University of Pennsylvania and the Massachusetts Institute of Technology (MIT) have been able to grow liver tissue with the tiniest of blood vessels using a sugar network for support. A tiny sugar structure also will easily dissolve away and add nutrients for the cells to survive.
As of right now, no lab has succeeded in 3D printing hearts, kidneys or livers to scale (though bladders have been created and are now in trial). But that does not mean this capability won’t be available in the near future. Every day is a day closer to being able to successfully print replacement organs for people that need them desperately.
Printing full sized functioning major organs may a few years off. But as 3D printer technology improves and the successes in the research lab improves, items like heart valves or arteries and smaller cell replacements are in the near future (5 years or less).
Related External Resources
http://youtu.be/9RMx31GnNXY – TEDMED Talk – Anthony Atala: Printing a human kidney
http://youtu.be/4nqw1yjyKEs – An Inkjet Made My Bladder!
http://youtu.be/JRBa9YifVTY – University of Iowa Biomanufacturing Laboratory Printing Organs