March 16, 2014 – Harvard bioengineers say they have taken a big step toward using 3-D printers to make living tissue. They’ve made a machine with multiple printer heads that each extrudes a different biological building block to make complex tissue and blood vessels.
Their work represents a significant advance toward producing living medical models upon which drugs could be tested for safety and effectiveness.
It also advances the ball in the direction of an even bigger goal. Such a machine and the techniques being refined by researchers offer a glimpse of the early steps in a sci-fi healthcare scenario: One day surgeons might feed detailed CT scans of human body parts into a 3-D printer, manipulate them with design software, and produce healthy replacements for diseased or injured tissues or organs.
Read more below and click the gifs for explanations.
“This is the foundational step toward creating 3-D living tissue,” said Jennifer Lewis, senior author of the study published Feb. 18 in the journal Advanced Materials, in a university release.
The work, performed at Harvard’s Wyss Institute for Biologically Inspired Engineering, allows engineers to embed vascular networks into 3-D printed cellular agglomerations. These tiny vessels are critical to increasing the size of synthesized tissues because they provide a path for nutrients in and wastes out of cells laid down deep inside the printed products. Such networks mimic those found in natural tissues.
To make the tissue construct, Lewis’s team produced three “bio-inks” that are laid down by separate printer heads. One ink contains extracellular matrix, a complex mixture of water, proteins and carbohydrates that connects individual cells together to form tissues. Another contains extracellular matrix and living cells. A third used to make the vessels unusually melts as it cools so that researchers could chill the sample and suck out the ink to leave behind hollow tubes.
Lewis and her team can then seed the hollow tubes with endothelial cells, which grow into blood-vessel lining.
“Tissue engineers have been waiting for a method like this,” said the Wyss Institute’s Dr. Don Ingber.
“The ability to form functional vascular networks in 3D tissues before they are implanted not only enables thicker tissues to be formed, it also raises the possibility of surgically connecting these networks to the natural vasculature to promote immediate perfusion of the implanted tissue, which should greatly increase their engraftment and survival.”
(Using their custom-built printer, the fugitive ink for the vasculature, and other biological inks containing extracellular matrix and human cells, the researchers printed a 3-D tissue construct.)