Lots of hearts need help healing. Each year, about 790,000 Americans experience a myocardial infarction, according to the U.S Centers for Disease Control and Prevention.
During an ischemic event, muscle cells obstructed by a blocked artery begin to die due to a lack of oxygen and other nutrients. These cells can’t regenerate; scar tissue replaces the lost cardiac muscle, which can leave patients physically debilitated.
Currently, treatment to repair post-heart attack damage isn’t available. But one team of researchers is on a mission to engineer cardiovascular tissues for application to regenerative medicine.
The researchers, from Michigan Technological University (MTU) and the University of Wisconsin, Madison, have introduced a new advancement that promises to help improve cardiac patient recovery: bioengineered cardiac patches.
According to a study published in Theranostics, the team, lead in part by Dr. Feng Zhao at MTU’s Department of Biomedical Engineering, successfully created a stem cell cardiac patch, made with engineered tissue. It contains tiny blood vessels that mimic those of a real heart muscle.
“The cardiac patch is completely biological, comprised of stem cells with vasculature that mimics real tissue that could help repair a heart,” Zhao said in a statement.
Zhao and her team’s engineered tissue has a dense, microvascular network. It physiologically replicates myocardial microvascular features. The cardiac patch, made from highly-aligned, decellularized, human dermal fibroblast sheets, has the potential to connect to native vasculature in order to transport nutrients and oxygen.
Implanting pre-vascularized tissue into the vascular system is challenging. Healing microvascular structures after a myocardial infarction requires dense, mature, capillary-like micro-vessel networks. Generally, engineered micro-vessels tend to be much larger than real heart tissue capillaries, which are the smallest vessels in the body at just five to 10 micrometers in diameter.
Furthermore, the dense micro-vessels must be aligned for electromechanical signal transaction. But like trying to fit together different-sized pipes into your home’s plumbing system, vessels of mismatched sizes won’t work well together to run water.
Micro-vessel networks typically aren’t dense enough to do the important job of supplying the heart with blood and other nutrients, either.
But to develop the refined cardiac tissue implant, Zhao and her team analyzed the mechanisms behind micro-vessel alignment to understand how to use biomaterials. They also reviewed the pros and cons amongst six different methods to align micro-vessels, which included electromechanical stimulation, surface topography, micro-scaffolding, microfluidics, surface patterning and 3D printing.
The next step is to test and refine the pre-vascularized cardiac patch in animal trials. Zhao and her team predict that ultimately, cardiac patches could be stacked on top of each other and implanted in the human heart to accelerate cardiac regeneration.
Last updated on 10/1/19.