A specially adapted 3D printer has been used to create biomaterials from multiple sources, an advance that could lead to bioprinting complex artificial tissues on-demand.
3D bioprinter has two key components: a custom-built microfluidic chip (pictured) and a digital micromirror. (Credit: Amir Miri)
The study, led by UCLA bioengineer Ali Khademhosseini, has been published in Advanced Materials.
“Tissues are wonderfully complex structures, so to engineer artificial versions of them that function properly, we have to recreate their complexity,” said Khademhosseini, who is UCLA’s Levi James Knight, Jr, Professor of Engineering at the UCLA Samueli School of Engineering. “Our new approach offers a way to build complex biocompatible structures made from different materials.”
According to UCLA, the technique uses stereolithography and a customised 3D printer designed by Khademhosseini that has two key components. The first is a custom-built microfluidic chip with multiple inlets that “print” a different material. The other component is a digital micromirror, an array of more than a million mirrors that move independently.
The researchers used different types of hydrogels – materials that, after passing through the printer, form scaffolds for tissue to grow into. The micromirrors direct light onto the printing surface, and the illuminated areas indicate the outline of the 3D object that’s being printed.
The light also triggers molecular bonds to form in the materials, which causes the gels to firm into solid material. As the 3D object is printed, the mirror array changes the light pattern to indicate the shape of each new layer.
The process is said to be the first to use multiple materials for automated stereolithographic bioprinting, an advance over conventional stereolithographic bioprinting, which uses one type of material. While the demonstration device used four types of bio-inks, the study’s authors said the process could accommodate as many inks as required.
According to UCLA, the researchers first used the process to make simple shapes, such as pyramids. Then they made complex 3D structures that mimicked parts of muscle tissue and muscle-skeleton connective tissues. They also printed shapes mimicking tumours with networks of blood vessels, which could be used as biological models to study cancers. They tested the printed structures by implanting them in rats and found that the structures were not rejected.
The study was funded by the US Office of Naval Research and the US National Institutes of Health.