Ischemia – the blocking or restriction of blood vessels - can cause loss of function in limbs and organs leading to heart attacks, strokes and gangrene. While larger vessels can be treated with surgery, smaller vessels are more complex.
The team, which included medical professionals and engineers, developed a 3D printed patch with embedded endothelial cells, the type of cells that line the interior of blood vessels. Not only did the patch result in the growth of new vessels - known as angiogenesis - the researchers were actually able to give structure to the growth, helping the vessels operate more effectively.
"Therapeutic angiogenesis, when growth factors are injected to encourage new vessels to grow, is a promising experimental method to treat ischemia," said Professor Christopher Chen from Boston University College of Engineering.
"But in practice, the new branches that sprout form a disorganised and tortuous network that looks like a 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 organising them."
Working with Boston biotech company Innolign, the team created one patch with an organised cell architecture and another where the cells were not organised in any specific way. Testing both on rodents, it was found that the organised patch performed significantly better, reducing the prevalence of ischemia.
“This pre-clinical work presents a novel approach to guide enhanced blood flow to specific areas of the body," said C Keith Ozaki, a surgeon at Brigham and Women's Hospital with expertise in leg ischemia.
"The augmented blood nourishment provides valuable oxygen to heal and functionally preserve vital organs such as the heart and limbs."
While results so far are promising, the researchers hope to be able to improve the technology by experimenting with different patch architectures. Using 3D printing will allow them to iterate quickly, as well as scale up to test in larger and more complex tissue environments.
"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," said Chen.