Bioengineers have conceived of a breakthrough technique for 3D bioprinting organ tissues. The novel method allows scientists to recreate the complex vascular networks that mimic the body's natural passageways for blood, air, lymph, and other vital fluids.
Printing complex vasculature
"One of the biggest road blocks to generating functional tissue replacements has been our inability to print the complex vasculature that can supply nutrients to densely populated tissues," said research lead Jordan Miller, assistant professor of bioengineering at Rice's Brown School of Engineering.
"Further, our organs actually contain independent vascular networks -- like the airways and blood vessels of the lung or the bile ducts and blood vessels in the liver. These interpenetrating networks are physically and biochemically entangled, and the architecture itself is intimately related to tissue function. Ours is the first bioprinting technology that addresses the challenge of multivascularization in a direct and comprehensive way."
In this context, multivascularization is important because form and function often go together.
"Tissue engineering has struggled with this for a generation," said Kelly Stevens assistant professor of bioengineering in the UW College of Engineering, assistant professor of pathology in the UW School of Medicine, and an investigator at the UW Medicine Institute for Stem Cell and Regenerative Medicine.
"With this work we can now better ask, 'If we can print tissues that look and now even breathe more like the healthy tissues in our bodies, will they also then functionally behave more like those tissues?' This is an important question, because how well a bioprinted tissue functions will affect how successful it will be as a therapy."
The business of transplant organs in a complicated one full of hurdles. First of all, there is the fact that there is great need for organ transplants that can not be met by human transplants alone. More than 100,000 people are on transplant waiting lists in the United States alone. Furthermore, those who do receive organs still risk organ rejection and have to be on immune-suppressing drugs.
Bioprinting has the potential to resolve both those issues by allowing doctors to print replacement organs from a patient's own cells. "We envision bioprinting becoming a major component of medicine within the next two decades," Miller said.
The team's new open-source technology is called the "stereolithography apparatus for tissue engineering," or SLATE and tests of its results have proven very positive.
For instance, experiments on the lung-mimicking structure found that the tissues were able to handle human-like flow and pulsatile breathing without bursting. Furthermore, the red blood cells could take up oxygen as they flowed through this 3D printed network.
That is not the only experiments the researchers undertook. The team also implanted 3D printed tissues loaded with primary liver cells into mice. The result was that the tissues successfully survived the implementation.
Now, the researchers plan on exploring many more options. "We are only at the beginning of our exploration of the architectures found in the human body," said Miller. "We still have so much more to learn."
The research is featured on the cover of this week's issue of Science.