A group of researchers from the University of Colorado Boulder have created a method of 3D printing that can create artificial blood vessel-like structures. This research, published in Nature Communications, provides evidence that 3D printing could engineer artery and tissue replacements for hardened blood vessels tethered to cardiovascular disease.
Integrating an oxygen inhibition layer between cured polymer structures to limit curing thickness during the manufacturing process, the team was able to imitate the highly structured and flexible geometry of blood vessels. “Oxygen is usually a bad thing in that it causes incomplete curing,” said Yonghui Ding, Postdoctoral researcher in Mechanical Engineering and the lead author of the study. “We utilize a layer that allows a fixed rate of oxygen permeation. By keeping tight control over oxygen migration and its subsequent light exposure, the researchers have the freedom to control which areas of an object are solidified to be harder or softer—all while keeping the overall geometry the same.”
Impressively, the researchers used a 3D printer built with parts purchased on eBay for a total cost of $500 to create these intricate microscopic structures.
“The idea was to add independent mechanical properties to 3D structures that can mimic the body’s natural tissue,” said Xiaobo Yin, Associate Professor in CU Boulder’s Department of Mechanical Engineering and senior author of the study. This technology allows us to create microstructures that can be customized for disease models.”
To test their system, the researchers printed three versions of the structure with a top beam accompanied by two support rods. All three structures were identical in material, shape, and size, differing only by rigidity. The two rods used in each system were either both soft, one soft one hard, or both hard. The researchers found that the harder rods supported the top beam, while the less rigid ones resulted in collapse of the beam.
The CU Boulder researchers believe that this method is “opening a new avenue towards 3D in vitro tissue fabrication.” They hope that their findings will increase release of personalized treatments for those suffering from cardiovascular disease and hypertension.
An article on CU Boulder’s site says that the researchers repeated this 3D printing trial with a small Chinese warrior figure, using this difference in rigidness, “so that the outer layers remained hard while the interior remained soft, leaving the warrior with a tough exterior and a tender heart.”
The printer the researchers constructed currently is capable of handling biomaterials down to 10 microns, which is roughly 10% of a human hair’s width. The team is hopeful that future studies will allow the printers capacities to improve even further. “The challenge is to create an even finer scale for the chemical reactions,” said Yin. “But we see tremendous opportunity ahead for this technology and the potential for artificial tissue fabrication.”
Additional authors of the study include Yao Zhai, Hang Yin, and Mechanical Engineering Professor Wei Tan. This research was funded by the National Institutes of Health as well as the National Science Foundation.