Jianyi "Jay" Zhang, MD, PhD brought his biomedical engineering expertise to UAB with a dream to create new tissue that can replace or protect damaged muscle after a heart attack.
Zhang took a major step toward that goal when he and colleagues protected pigs from post-heart attack heart failure. The researchers placed a mat of fibrin over the area where muscle had died and injected three types of cardiovascular cells underneath the mat. This is somewhat akin to starting new lawn by scattering grass seeds beneath a protective layer of hay. The fibrin helped some of the injected cells survive and grow, and they in turn protected the heart from further damage.
Zhang is launching a new effort to improve heart repair. Instead of injecting individual cells and hoping they take seed, Zhang plans to robotically build and grow a mat of heart tissue made from individual cells, using a custom 3-D printer. Surgeons will then place this custom mat of living cells over the dead, infarcted tissue of the heart, somewhat akin to starting a new lawn by laying sod.
"We will make our own printer, using machinery, robotic and computer science experts," said Zhang, who is the leader of UAB Biomedical Engineering, a joint department of the UAB School of Medicine and School of Engineering. "A robotic arm will pick up cells of various types from petri dishes and place them onto fine needles that are a few microns apart. The growing cells fuse after three to seven days, and the shape is based on the needles. Then we can lift off the tissue. It is scaffold-less tissue engineering."
The piece of engineered tissue will be printed-to-order to match the size and shape of the dead tissue in the heart, as measured by MRI. All the work must be done under sterile conditions in a culture medium that provides the oxygen and nutrients to keep the cells alive.
This UAB myocardial tissue patch will be tested in a pig model before it can move to human trials. "We want to take it to clinical practice in seven years," Zhang said.
UAB's expertise in heart electrophysiology will be vital because the patch could cause heart arrhythmias if it interferes with the timing of the electrophysiological wave that directs each smooth contraction of the pumping heart.
