3D Printing Provides Building Blocks of Healing in Scaffold Design

DOUGLAS FARMER, SENIOR EDITOR
doug.farmer@photonics.com

A group of researchers has demonstrated that assembling a network of tiny, approximately 1.5-mm³ blocks with the aid of optical technology can be an effective way to accelerate healing in tissue and bone. Using Lego blocks as inspiration, they even learned that filling these blocks with different materials could direct specific healing to where it was needed most.

The blocks were essentially used as a scaffolding in an experiment with laboratory rats. The research was led by Luiz Bertassoni, an associate professor in biomedical engineering in the Oregon Health & Science University School of Medicine, along with others from his institution and from the University of Oregon, New York University, and Mahidol University in Thailand.

“The rationale behind these Lego-like scaffolds was that we wanted to be able to grow parts of a complex tissue in the lab, where the conditions can be just right for maturation and growth, and then stack these individual building blocks together just before implanting them in the body,” said Ramesh Subbiah, a postdoctoral fellow who works with Bertassoni. “These individual blocks can then coalesce into more complex tissues/organs after implantation.”

He said the blocks have been considered for spinal fusion and treatment of long bone defects. They used digital light processing (DLP) 3D printing to make the intricate structures that could be arranged in thousands of configurations.

In their published study, researchers explained that they used a lithography-based 3D-printing strategy to construct a miniaturized modular microcage scaffold system, which can be assembled and scaled manually. Just as importantly, the hollow microcage design allows each unit to be loaded with different biological materials, allowing for a patterning of therapeutics with different treatments applied to specific areas of a wound or condition.

An assembled microcage scaffold. Courtesy of Bertassoni Lab/OHSU.

To fabricate the components, they used a hydrogel 3D-printing approach to create microgels in the shape of cuboidal, spiral, triangular, square, cylindrical, star, and five-pointed flower-like geometries composed of methacrylated gelatin, which were printed using a (DLP) 3D-printing setup. Using fluorescent molecules, they discovered that the material held inside was dispersed in nearby tissue and helped restore it at a more efficient and effective pace than other methods, such as inserting rods.

“The DLP printing method uses blue light to cure the resin. The light curing of the resin is the first step in the process of manufacturing of the scaffold material,” Subbiah said. “The microgels that are loaded inside the microcages also use a DLP orienting method. These gels are printed in high numbers and then injected into the cage before the ‘Legos’ are stacked, and the whole things is implanted.”

This research was published in Advanced Materials (www.doi.org/10.1002/adma.202001736).