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American bioengineers have found a way to create extremely entangled vascular networks that mimic the body's natural pathways for blood, air, lymph, and other vital fluids.
The findings, reported Thursday in the journal Science, could help lift an obstacle for 3D printing replacement organs.
One of the major barriers to creating functional tissue replacements was that surgeons could not print the complex vascular system that can provide nutrients to densely populated tissues, said Jordan Miller, co-author of the journal, Assistant Professor Bioengineering at Rice University.
In addition, the airways, blood vessels in the lungs or bile ducts in the liver are entangled physically and biochemically, making artificial constructions more difficult, according to Miller.
The researchers created a bio-printing technology to make soft hydrogels one layer at a time. Their pixel sizes vary only from 10 to 50 microns. The layers are printed from a liquid solution that becomes solid when exposed to blue light.
According to the study, they managed to limit solidification to a very thin layer in order to produce soft, biocompatible water-based gels, with a complex internal architecture.
The researchers designed a hydrogel model of an air sac mimicking the lungs, strong enough not to burst during the bloodstream and the "breathing", an entrance and exit of the lungs. rhythmic air simulating the pressures and frequencies of human breathing.
The results showed that red blood cells could absorb oxygen as they pbaded through a network of blood vessels surrounding the "breathing" air sac.
They also 3D-printed tissues loaded with primary liver cells before implanting them into mice with chronic liver injury. Then the liver cells survived the implantation.
"The complexity of the liver means that there is currently no machine or therapy that can replace all of its functions in the event of a failure of this one, and bio-printed human organs could someday provide this therapy." Kelly Stevens, co-author of the newspaper, said with the University of Washington.
Miller said his lab is already using new design and bio-printing techniques to explore even more complex structures.
"We envision bio-printing becoming a major component of medicine in the next two decades," Miller said.
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