Bioengineers build blood vessels

Biomedical engineers at

have created an implantable system of artificial scaffolds around which blood capillaries are grown to provide vital support for tissues in the body.

Capillaries are the finest of blood vessels, bringing oxygen and nutrients to body tissues and transporting away waste products. A study led by Erin Lavik, assistant professor of Biomedical Engineering shows that the fine network of blood vessels can be formed around a sponge-like structure. Implanted into the body, the vascular networks proved stable for up to six weeks and were able to connect with larger blood vessel structures.

"This expands our understanding of the neuro-vascular niche and opens up ways to address repair of severed nerves," said Joseph Madri professor of pathology at Yale School of Medicine and a co-author. "We can now study what affects the attraction and repulsion of nerve growth and drug delivery in a model system that can be used in vitro and in vivo."

The researchers created a "micro-scaffold" of a macroporous hydrogel polymer, a highly water-absorbent, sponge-like material with a structure of connected pores for cells to grow on and through. They then seeded the hydrogel scaffolds with endothelial cells that make up blood vessel structure along with nerve progenitor cells from the brain.

Because there is often an association of nerve connections with vascular networks, they tested to see if a combination of the blood vessel-forming and nerve-forming cells would enhance development of the vascular networks.

"By their nature, hydrogels are well suited for the transport of soluble factors, nutrients or drugs, and waste," said Lavik. "The hydrogel scaffold materials are generally highly biocompatible and safe to implant due to the presence of large volumes of water."