Professor Christopher Chen, director of the biological Design Center at Boston University, is in the process of developing 3D printed patches that are infused with cells to grow healthy blood vessels to treat ischemia.
Ischemia is a condition in which narrow, hardened or blocked blood vessels starve tissues. It can the heart from receiving enough oxygen to function, according to the Mayo Clinic.
The condition can also cause stroke, gangrene in limbs and other serious conditions.
Treatment for ischemia often involves a procedure to open blocked arteries or bypass surgery. However, treatment is harder in complex vessels that are small or damaged before treatment.
Chen and his clinical partners Keith Ozaki, Brigham and Women’s Hospital surgeon), and Joseph Woo, head of cardiothoracic surgery at Stanford University, developed the patch that grows new vessels while simultaneously avoiding complications of other treatment approaches.
“Therapeutic angiogenesis, when growth factors are injected to encourage new vessels to grow, is a promising experimental method to treat ischemia,” said Chen in a press release. “But in practice, the new branches that sprout form a disorganized and tortuous network that look 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.”
Two patches were created with endothelial cells – one with pre-organized cells in a specific architecture and one where cells were injected without organizational structure. In vivo results showed that patches that had a pre-organized structure that reflected an improvement in reducing ischemia. Patches with no organization had the hairball effect.
“This pre-clinical work presents a novel approach to guide enhanced blood flow to specific areas of the body,” Ozaki said. “The augmented blood nourishment provides valuable oxygen to heal and functionally preserve vital organs such as the heart and limbs.”
Since the vessels have to be printed on such a 100-micronn scale to fit tiny blood vessels, Chen enlisted the help of Boston biomedical technology company Innolign, which he helped found. Using 3D printing allows for researchers to change and test designs quickly while also allowing for scalability.
“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. “The pre-organized architecture of the path 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 3D printing approach is still in its early stages, but the researchers say that the results are promising. Chen and his team are going to work more on the scalability of the patches and work on structures that could be better than what they are currently testing.
“This project has been long in the making, and our clinical collaborators have been indispensable to the success of the project,” said Chen. “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.”
The research was published online in the journal Nature Biomedical Engineering.
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