Harvard Team Develops Method to 3D Print Blood Vessels

Researchers at Harvard’s Wyss Institute and John A. Paulson School of Engineering and Applied Science have made significant strides toward the goal of growing functional human organs outside the body. Their new method, detailed in Advanced Materials, involves 3D printing vascular networks that closely mimic natural blood vessels.

The team, led by Jennifer Lewis, developed a technique called coaxial sacrificial writing in functional tissue (co-SWIFT). This method builds on their previous work and allows for the creation of multilayered vascular structures. These structures are composed of a shell of smooth muscle cells and endothelial cells surrounding a hollow core for fluid flow, embedded within human cardiac tissue.

Paul Stankey, first author of the study, highlighted the innovation: co-SWIFT  “recapitulates the multilayer architecture found in native blood vessels, making it easier to form an interconnected endothelium and more robust to withstand the internal pressure of blood flow.”

Key to their success was the development of a unique core-shell nozzle with two controllable fluid channels for the collagen-based shell ink and gelatin-based core ink. This setup allows for the creation of interconnected branching networks essential for oxygenating tissues.

To validate their method, the team first printed multilayer vessels into a transparent hydrogel matrix and a porous collagen-based matrix called uPOROS. They then moved to more biologically relevant materials, infusing the shell ink with smooth muscle cells and perfusing endothelial cells into the vasculature. Both cell types remained alive and functional after seven days.

The researchers further tested their method by constructing cardiac organ building blocks (OBBs) and printing a biomimetic vessel network into the cardiac tissue. The printed vessels exhibited the double-layer structure of human blood vessels, and the cardiac tissue responded to common cardiac drugs, demonstrating its functionality.

Future work will focus on integrating self-assembled capillary networks with 3D-printed blood vessels to more closely replicate the structure and function of human blood vessels.