Researchers at Stanford University have developed a cutting-edge computational platform that can rapidly design and 3D print complex vascular networks—an essential step toward building functional bioprinted organs. Published in Science on June 12, the platform generates vascular structures that resemble natural human blood vessel networks up to 200 times faster than previous methods.

This innovation tackles a major bottleneck in tissue engineering: creating vascular systems capable of delivering oxygen and nutrients to every cell within a bioprinted organ. Without this critical network, scaling up tissue constructs to full organ size has remained out of reach.

The Stanford system uses a custom algorithm that designs vascular “trees” by replicating the branching patterns of real blood vessels while incorporating fluid dynamics simulations to ensure effective blood flow. For example, designing a vascular network for a human heart—with about one million vessels—takes just five hours using this platform.

“With tissue engineering, you can’t scale up tissues without a blood supply,” explained Alison Marsden, professor at Stanford’s Schools of Engineering and Medicine and co-senior author of the study.

Using a 3D bioprinter, the team successfully produced a vascular network with 500 branches and tested a simplified model using human embryonic kidney cells. In this test, they printed a thick ring of tissue embedded with living cells and ran 25 printed vessels through it. When oxygen and nutrients were pumped through the channels, the surrounding cells remained viable, proving the network’s functionality.

Currently, the printed channels function as primitive vessels but do not yet include key biological components like muscle or endothelial cells. “This is the first step toward generating really complex vascular networks,” said Dominic Rütsche, postdoctoral scholar and co-first author. “We can now print at levels of complexity never seen before, though these are still early-stage structures.”

To encourage further research, the team has released their vascular design software through the open-source SimVascular project. Building on this achievement, the researchers are now working to combine these vascular networks with lab-grown heart muscle cells derived from human stem cells.

“We’ve already managed to generate enough heart cells to print an entire human heart,” said Mark Skylar-Scott, assistant professor of bioengineering and co-senior author. “Now, we have the tools to build the complex vascular tree needed to keep those cells alive.”

The development marks a significant step toward the long-term goal of creating transplantable, patient-specific organs—a potential lifeline for the more than 100,000 people currently waiting for organ transplants in the United States. Although fully functional printed organs are still years away, this breakthrough in vascular network printing moves the field meaningfully closer to that reality.

By Impact Lab