The architecture of the patch organizes cells to enhance blood flow.

Researchers have engineered a 3D patch to overcome a lack of blood flow and oxygen to organs, which is a condition known as ischemia. Ischemia can cause gangrene, heart attack and stroke. Treatment for the condition has been largely limited to usage of blood thinners or surgery; however, surgery is generally for larger vessels. It is not generally a solution for smaller blood vessels, or where the area has already been damaged due to prior treatment. Director of the Biological Design Center and Professor Christopher Chen (BME, MSE), along with C. Keith Ozaki, MD, FACS, a surgeon at Brigham and Women’s Hospital who has expertise in leg ischemia, and Joseph Woo, MD, the head of cardiothoracic surgery at Stanford University have developed a method to combat this condition using 3D-printed patches infused with cells, that aid in the growth of new blood vessels.

“Therapeutic angiogenesis, when growth factors are injected to encourage new vessels to grow, is a promising experimental method to treat ischemia,” Chen described of the patch. “But in practice, 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.”

 In the In vivo results of patches with endothelial cells pre-organized into a specific architecture, there was a definite improvement in the presence of ischemia in the mouse models. Ozaki commented on these initial, promising results. “This pre-clinical work presents a novel approach to guide enhanced blood flow to specific areas of the body,” he noted. “The augmented blood nourishment provides valuable oxygen to heal and functionally preserve vital organs such as the heart and limbs.”

Ultimately, form and function are inextricably linked; the organized architectural structure of the cells is made possible because of the 3D printed material. “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,” Chen explained. “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 team will continue work with the patches going forward, experimenting with new architectural structures which may prove even more effective, as well as working on the scalability of the patches. Chen stated the possibilities for future work on this breakthrough is indeed promising, and there is room in the space for collaboration. “As a bioengineer, we were focused on how to actually build the patch itself, while the clinical perspective was critical to the design process. We look forward to continuing our partnerships as we move forward.”