Scientists are hoping that a specially adapted 3D printer made to build therapeutic biomaterials will help aid medical research by printing test materials so complex as to closely approximate real human tissue.
“Tissues are wonderfully complex structures, so to engineer artificial versions of them that function properly, we have to recreate their complexity. Our new approach offers a way to build complex biocompatible structures made from different materials,” says Ali Khademhosseini of UCLA, who led the study, in a .
Khademhosseini's 3D printer has two key parts that give it this complexity. One of them is a custom-built microfluidic chip handles the flow of liquids inside micrometer-sized channels. It has multiple inlets that each “prints” a different material. It also has an an array of over a million tiny mirrors, each of which move independently.
They all work together in a process known as "automated stereolithographic bioprinting." The micromirrors direct light onto the printing surface. These illuminated areas trace the outline of the 3D object that’s being printed. The light also triggers molecular bonds to form in a variety of hydrogel bioinks, materials that are in tissue engineering. These molecular bonds firm and stiffen to extent that the bioinks turn into solid material.
Khademhosseini says that the researchers used four types of bioinks, but says in that they could use as many as needed.
Starting with relatively simple shapes like pyramids, the team soon moved on to structure that imitated parts of muscle tissue and muscle-skeleton connective tissues. They then built tumors with networks of blood vessels. These 3D-built tumors have the potential to be used as biological models for studying various cancers.