Holiday Desert With Fruit Suspended in Jello-O

A method to grow a self-assembling, functional network of blood vessels at a size relevant for human use has been found by Jason Gleghorn, an assistant professor of biomedical engineering at the University of Delaware and his collegues.

Here’s the ScienceDaily:

The team embedded human blood vessel cells into a gel made of collagen, a protein found in connective tissue such as skin and joints. The goal was to determine the physical conditions necessary to make the cells grow, multiply and connect with each other so that a network of blood vessels assembled itself.

They succeeded.

“It looks kind of like the holiday dessert with fruit suspended in Jell-O,” said Gleghorn of the cells in the collagen gel. “You have a bunch of cells randomly distributed throughout the volume of the gel, and if they are sparsely distributed, it gets very hard for them to talk to each other and form connections to form vessels. The languages they use are chemical signals and physical forces.” The key is to find the sweet spot of stiffness, stiff enough so that neighboring cells can interact with the material and each other, but not so stiff that the cells can’t move.

The team also found that by perturbing their system in a specific way, they could affect the size and shape of the vessel networks under assembly.

“From larger vessels to much smaller microvessels, which are really hard to make, we can now tune the vessel network architecture with the initial starting parameters,” said Gleghorn. This means that the new system could have applications from forming larger vessels deep within the body to tiny capillaries, the teeny vessels in your fingertips.

Gleghorn’s team also found that their lab-grown blood vessels were perfusable, suggesting that blood could flow through them without leaking out of the vessels into surrounding gel. The vessel networks can also form throughout a variety of shaped gels, meaning that this system could be useful for building blood vessel networks in tissues with complicated shapes, such as the meniscus cartilage that pads your knees or a large skin graft for burn patients.