Assistant Professor Katherine Yanhang Zhang (AME) and Associate Professors Joyce Wong (BME) and Xin Zhang (MFG) won a National Science Foundation grant allowing them to poke, prod and stretch tissue engineered blood vessels. Their observations will reveal how well this tissue mimics natural blood vessels.
At first glance, a blood vessel looks like a simple tube, but its structure and function are complex, making it a challenge to replicate in the lab.
“The blood vessel is very complicated material. It is made up of hierarchical structures, multiple levels of structure, and this study will help us relate the structural components to the behavior of the tissue,” said Katherine Yanhang Zhang.
The researchers will pool their expertise in mechanical, biomedical and manufacturing engineering to test the mechanics and biochemical properties of blood vessels built from human cells in the laboratory against the standards of those created by the body itself.
Tissue-engineered blood vessels may eventually substitute for the real thing in bypass surgeries, in which new vessels are needed to replace diseased ones.
Wong grows the engineered vessels from human cells on a self-dissolving scaffolding. “The structural organization of the tissue is very important. Blood vessels have micro-patterns, so we try to create micro-patterns in our tissue engineered blood vessels,” she said.
Katherine Yanhang Zhang measures the mechanical behavior of the engineered tissue — its physical strength and elasticity — by using a biaxial test that stretches the tissue in two directions. This technique mimics the stress the tissue would experience in the body. In addition, she sets up mechanical models that connect the structure of blood vessels to their mechanical functionality.
Xin Zhang takes a closer look at individual cells and sub-cellular properties of the engineered tissue. She uses micro-electro-mechanical systems (MEMS) to study the forces exerted within cells and how these affect blood vessel function.
In addition to growing the engineered vessels, Wong examines their biochemical properties, making sure the cells that comprise the engineered blood vessels secrete the same molecules and chemical signals that natural blood vessels would.
Their collaboration lets the researchers use several different techniques to study properties of the tissue engineered blood vessels, from the molecular level through to the behavior of the tissue as a whole.
“There are ways to work together,” said Xin Zhang. “We should not work independently all the time, but communicate and try to collaborate. It’s definitely something refreshing and very important.”