Printing the Future, Together: Biomedical and Mechanical Engineering Professors Use Interdisciplinary Collaboration to Enhance the Field of 3D-Printed Tissues

According to biomedical engineering professor Hongjun Wang, the science of 3D-printing functional biological tissues and organs has a long way to go, but one has to start somewhere. That ephemeral “somewhere” is the passion of himself and of Robert Chang, associate professor and associate chair for graduate studies in the Department of Mechanical Engineering.

Although these two professors have different research focuses and experiences, they have a common interest in the “upstream” elements of 3D printing. They both research the procedures and processes that inform how to best create biocompatible scaffolds, 3D models that mimic the extracellular matrix environment of the body. These scaffolds can then be seeded with cells to create living tissues for applications such as organ replacement or serve as the testing models for therapeutics. 

While the professors have a number of overlapping interests, however, they are quick to explain that their differences are what has made their partnership for the last 10 years so successful. 

Chang, whose work focuses on quantitative strategies, uses computational and mathematical modeling to optimize printing parameters and enhance the final product of tissue constructs. He has been working with 3D printers for over 20 years. 

Wang’s decades of expertise is more on the biological end of the spectrum, investigating and optimizing biomaterials and the microenvironment for greater success in cell-seeding and long-term biocompatibility. 

Together, their combined experience across their different focuses and departments allows for each of them to take a more holistic approach in tackling the very complex and exciting field of 3D printing for biological applications. 

Chang sees their years-long work together as bearing some of the hallmarks of what makes collaborative work successful.

“It is undesirable to be exactly the same,” said Chang. “We don’t need to be clones of each other: what we need to have are complementary, different focuses, allowing us to help answer questions that we can’t on our own.”

The two colleagues see a sign of their success in their students. Both professors have served on the Ph.D. committees of the other’s students, as well as jointly published with them. This exchange benefits both the students and the professors.

Said Wang, “His students can understand how different materials behave, and mine understand what the processing involves. It gives more context [to us both].”

A cell (red) growing in between 3D-printed grids of polymeric filaments with localized cell adhesive domains (green). The cell nucleus appears in purple.

The professors’ next collaborative challenge is manipulating the scale of 3D-printed scaffolds.

Traditional 3D-printed filament is on the order of 200-300 micrometers, the thickness of a couple pieces of paper. However, at the cellular level, filaments that thick might as well be two-dimensional, as they are so much larger than the cell bodies that the scaffold is being seeded with. Creating finer filaments on the order of fractions of a micrometer more accurately mimics the extracellular matrix fibers in an organism and allows cells, usually only between 10-100 micrometers wide, to grow into the scaffold more effectively.

Additionally, the pair are looking into how the structural, biological mapping of the scaffold can inform what type of cell a seeded stem cell grows into. With the correct printed shape, a stem cell can be coded to become a different tissue, such as bone, cartilage or adipose (fat-storing) tissue. 

These two research questions make great use of both of their skill sets.

“We’re trying to use quantitative aspects of technology,” said Chang, “and move [the research] beyond trial and error.”

For Chang, that means high-speed camera footage of a bioprinter at work, machine learning and numerical modeling to understand how the printing is taking place. For Wang, that’s looking at elements of the materials, such as the bioink, as well as the realities of the microenvironment that is created in the 3D-printing process. 

In addition to getting support from each other, the colleagues also leverage Stevens’ resources.

“Stevens has a good collection of different printers,” said Wang, allowing the pair to “really push the field by taking advantage of the different hardware.”

Wang and Chang also hope to continue to open their collaboration up to beyond just their groups. Both see great potential in Wang's work as director of the Center for Healthcare Innovation, which has a working group focused on biofabrication.

“We want to bring other faculty into the fold,” said Chang. “We can all form a symbiosis and mutually benefit from those conversations with one another.”

The two literally finished each other’s sentences to outline their philosophy on successfully working together. 

Started Wang, “The beauty of complementary collaboration, coming from different angles and a common interest—” 

Finished Chang, “—That’s where new ideas arrive.”