Report

Major Obstacles to 3D-Printing

Our additive manufacturing technology has progressed almost to the point where we have complete mastery over the shape of our designs. The next steps, material and then behavior are the domains where the lion’s share of our challenges lie. On the path to the viable manufacturing of 3D-printed organs, the obstacles can be grouped together under function and integration.

There’s a large plethora of challenges to printing fully functional organs. The most immediate, and arguably one the most challenging, issue is vascularity. Our organs are perforated with innumerable blood vessels that provide blood and nutrition to our cells, as well as transporting cells to different locations within the organ. This system of capillaries, veins and arteries, apart from being very complex, have unique physical properties that are very difficult to recreate using a 3D-printer. Without a functioning vascular network, the printed organs will inevitably die, just as a country without proper infrastructure. In 2014, researchers at the University of Sydney succeeded in creating a vascular network by coating tiny fibers in a protein mixture, hardening it with light, and then removing said fibers. The result was a complex network of capillaries. However, there is still a long ways to go before we can create fully-functioning, vascular organs. Firstly, more complex networks have to be created, using not only capillaries but veins and arteries as well. Then, scientists have to find a process to print organs around these vascular networks, or print both the vascular network and the surrounding organ simultaneously.

Another obstacle to functionality is the composition of the organs. Human tissue is relatively homogenous, with a smaller variety of cells. Our organs are very specialized, complex structures, comprised of various types of tissue and smaller structures. Though we are capable of printing tissues with more than one types of cells, organs such as the liver are a different beast entirely. Additionally, these cells can only coexist in very specific places relative to each other. Improper placement results in incorrect or nonexistent interaction between the various cells in an organ. Creating printers that can extrude all of the types of cells in the exact locations remains a logistical challenge that we have yet to overcome.

Integration is the other major obstacle to viable 3D-printed organs. Even if a patient had a fully functional organ on hand, there are still many things that can go wrong. Rejection used to be the biggest problem, occurring when the patient’s immune system identifies the implanted organ as foreign and rejects it from the body. It is a very costly problem, wasting both time and money. If a patient’s body rejects an implant, there is little to no chance of reusing the organ, meaning that it is effectively wasted. 3D-printing minimizes this complication by using the patient’s own cells to construct the organ. Though rejection is not impossible, it is no longer the threat it used to be and could be managed with immunosuppressant drugs. What does pose an issue is ensuring that the body properly interacts with the organ. Growing nerves inside an organ and integrating them with the patient is a task even more difficult than vascularity. A few months, scientists printed a silicone guide that was attached onto damaged nerves to help them regenerate. Though this would be useful in integrating new organs into the body, the fabrication of entirely new nerves has not yet been successfully attempted; doing so would require jump-starting said nerves to being sending and receiving impulses.

Despite the seemingly insurmountable challenges that face the scientific community, many are confident that we will have fully functioning printed hearts within 20 years. More complex organs such as the liver and kidneys may take up to 40 years.