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Tuesday, June 30, 2020By the A.M. Costa Rica wire services Powdered sugar is the special ingredient in a recipe for mimicking the body’s intricate, branching blood vessels in lab-grown tissues, announced Rice University on Monday. According to the Houston based university, Rice bioengineers showed how they could keep densely packed cells alive for two weeks in relatively large constructs by creating complex blood vessel networks from templates of 3D-printed sugar. “One of the biggest hurdles to engineering clinically relevant tissues is packing a large tissue structure with hundreds of millions of living cells,” said study lead author Ian Kinstlinger, a bioengineering graduate student in Rice’s Brown School of Engineering. “Delivering enough oxygen and nutrients to all the cells across that large volume of tissue becomes a monumental challenge.” Kinstlinger explains that nature solved this problem through the evolution of complex vascular networks, which weave through our tissues and organs in patterns reminiscent of tree limbs. The vessels simultaneously become smaller in thickness but greater in number as they branch away from a central trunk, allowing oxygen and nutrients to be efficiently delivered to cells throughout the body. So, Kinstlinger with a blood vessel template, 3D-printed from powdered sugar. He is lead co-author of a study that showed that lab-grown tissues made from such templates had sufficient blood flow to sustain densely packed cells. “By developing new technologies and materials to mimic naturally occurring vascular networks, we’re getting closer to the point that we can provide oxygen and nutrients to a sufficient number of cells to get meaningful long-term therapeutic function,” Kinstlinger said. The sugar templates were 3D-printed with an open-source, modified laser cutter in the lab of study co-author Jordan Miller, an assistant professor of bioengineering at Rice University. “The 3D-printing process we developed here is like making a very precise creme brulee,” said Miller, whose original inspiration for the project was an intricate dessert. Miller said the complex, detailed structures are made possible by selective laser sintering, a 3D-printing process that fuses minute grains of powder into solid 3D objects. In contrast to more common extrusion 3D printing, where melted strands of material are deposited through a nozzle, laser sintering works by gently melting and fusing small regions in a packed bed of dry powder. "Both extrusion and laser sintering build 3D shapes one 2D layer at a time, but the laser method enables the generation of structures that would otherwise be prone to collapse if extruded," he said. “There are certain architectures — such as overhanging structures, branched networks and multivascular networks — which you really can’t do well with extrusion printing,” said Miller, who demonstrated the concept of sugar templating with a 3D extrusion printer during his postdoctoral studies at the University of Pennsylvania. Miller began work on the laser-sintering approach shortly after joining Rice in 2013. Sugar is especially useful in creating blood vessel templates because it’s durable when dry, and it rapidly dissolves in water without damaging nearby cells. To make tissues, Kinstlinger uses a special blend of sugars to print templates and then fills the volume around the printed sugar network with a mixture of cells in liquid gel. The gel becomes semi-solid within minutes, and the sugar is then dissolved and flushed away to leave an open passageway for nutrients and oxygen, the university said in its statement. ---------------------------------- How could this discovery speed the method of generating tissue for human use? We would like to know your thoughts on this story. Send your comments to news@amcostarica.com |
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