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3-D Printed Patch Helps Grow New Blood Vessels

Heart in rib cage illustration
(CIRM.gov)

14 June 2017. A biomedical engineering team developed a printed patch infused with cells that in lab animals grows new blood vessels to counteract blocked or hardened arteries. Researchers led by Boston University engineering professor Christopher Chen published their findings in yesterday’s issue of the journal Nature Biomedical Engineering (paid subscription required).

Chen and clinical colleagues at University of Pennsylvania, Stanford University, and Brigham and Women’s Hospital in Boston, are seeking better options for patients with ischemia, where blood flow is restricted due to narrowing or hardening of arteries. When the blood flow and oxygen are impaired to heart muscles it’s known as coronary artery disease or coronary heart disease. Ischemia can also occur in blood vessels affecting the brain, leading to stroke. Gangrene can result as well when blood flow is blocked to body tissue, particularly in the limbs.

Surgery is one of the few options available to ischemia patients, but it’s not suitable for individuals that cannot tolerate the procedure, or in some cases involving smaller blood vessels. For these circumstances, Chen’s team developed a patch infused with endothelial cells, the cells lining the inside of blood vessels, to encourage  angiogenesis, the growth of new blood vessels that bypass the veins or arteries restricted by ischemia.

The researchers needed to address another issue with angiogenesis, the haphazard way new blood vessels can grow, when a more structured and organized growth pattern is needed. Chen notes in a university statement that “the new branches that sprout form a disorganized and tortuous network that looks like sort of a hairball and doesn’t allow blood to flow efficiently through it. We wanted to see if we could solve this problem by organizing them.”

The patches in the study were produced by Innolign Biomedical, a company in Philadelphia co-founded by Chen developing implanted engineered tissue to encourage blood vessel growth in people with ischemic heart disease. The company produced 2 types of patches, one with an organized structure of endothelial cells, and a second patch that simply transfers the cells into tissue. Both patches produce very small blood vessels, of about 100 microns.

The team tested the patch implants on lab rodents induced with ischemia in their hind legs or myocardial infarction, commonly known as heart attack, from blocked arteries. The results show patches with a structured cell architecture produce more new blood vessels, as well as prevent more capillary loss and muscle atrophy in the animals than the patches only transferring cells.

“One of the questions we were trying to answer is whether or not architecture of the implant mattered, and this showed us that yes, it does, which is why our unique approach using a 3D printer was important,” says Chen. “The pre-organized architecture of the patch helped to guide the formation of new blood vessels that seemed to deliver sufficient blood to the downstream tissue. While it wasn’t a full recovery, we observed functional recovery of function in the ischemic tissue.”

The researchers next plan to improve the scalability of the patch, and try different architectures to improve growth of new blood vessels.

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