The problem with bioprinting 3D slabs of living tissue is that, without blood vessels to deliver oxygen and nutrients the printed cells on the interior of the slab suffocate and die.
To avoid this, researchers at Harvard’s Wyss Institute for Biologically Inspired Engineering have developed a special bioprintable ink that melts into a liquid when it’s cooled. This ink is used to trace blood vessels during the layer-by-layer printing of a complex tissue; then the structure is chilled and the ink is sucked out, leaving a hollow tube that can function as a blood vessel. Human endothelial cells are injected into the matrix to develop the vessel lining.
The researchers now hope to produce bioprinted functional 3D tissue viable enough to screen drugs for safety and effectiveness.
Scientists could also use the printed tissue constructs to shed light on activities of living tissue that require complex architecture, such as wound healing, blood vessel growth or tumour development.
“Tissue engineers have been waiting for a method like this,” said Don Ingber, M.D., Ph.D., Wyss Institute Founding Director. “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”.
Watch how Wyss researchers use their new 3D printing method to create complex living tissue constructs, complete with tiny bioprinted blood vessels…