“Up until this point, printing a synthetic, plastic model and perfusing it with different types of media has been done. But when it comes to hydrogels, and adding cells, and then having this flow going through — this is something that is a lot more complex, and no one has really tried this before,” said Serpooshan, assistant professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory. “We bioprint with soft hydrogels that mimic heart tissue, and we add cells that look exactly like the real heart tissue cellular structure. Then we perfuse with the flow that mimics the developing heart flow.”

Nothing that exists now can replicate heart development in quite the same way, Serpooshan said. Animal models are imperfect substitutes for human heart development, and 2D models lack fidelity to the three-dimensional structures and flow at play.

“Having a bioprinted, engineered model that you can print hundreds of is one of our main advantages. You can order the machine to print hundreds of consistent models,” Serpooshan said. “This allows us to change parameters and study how cells behave without using any animals or even going to clinical trials.”

That means the models could be used to accurately test promising new drugs. They could also be used to help surgeons hone their techniques and develop new methods. Early versions of the models have been used by Serpooshan’s close collaborator Holly Bauser-Heaton in just that way. She’s a pediatric cardiologist at Emory.

In particular, Serpooshan and his team are focused on the velocity of blood flow through the developing heart in all three dimensions and the shear stresses that flow exerts on heart cells. Serpooshan said these are critical signals to cells that guide when they grow or move or change. When flow is altered, so, too, is the tissue development.

Building the models requires detailed imaging and processing to turn the scans into 3D structures before printing can begin. Serpooshan said other Coulter Department faculty, including Lakshmi “Prasad” Dasi, David Frakes, and Brooks Lindsey, as well as collaborators at Emory School of Medicine, including Bauser-Heaton and Timothy Slesnick, bring key expertise to the work.

Once his team has functioning models, they’ll be able to study two other key conditions along with blood flow that make up the microenvironment around cells as the heart forms and could affect their behavior: stiffness of the tissues and the concentrations of the different proteins in those tissues.

Data suggests all three contribute to abnormalities that lead to congenital heart defects. The question is, how significant is their role?

“Gaining knowledge about some very complex and vague processes that no one has been really able to study in such precision is going to be one of the main outcomes,” Serpooshan said.