Scientists have developed the first structure to grow small human blood vessels – creating a 3-D test bed that offers a better way to study disease and test drugs than animal research. The new structure, created by bioengineers at the University of Washington, also opens up the possibility of growing human tissue for transplant.
The findings are published this week in the Proceedings of the National Academy of Sciences.
First author Ying Zheng explains: "In clinical research you just draw a blood sample but with this, we can really dissect what happens at the interface between the blood and the tissue. We can start to look at how these diseases start to progress and develop efficient therapies."
Zheng first built the structure out of the body's most abundant protein, collagen, while working as a postdoctoral researcher at Cornell University. She created tiny channels and injected this honeycomb with human endothelial cells, which line human blood vessels.
During a period of two weeks, the endothelial cells grew throughout the structure and formed tubes through the mould's rectangular channels, just as they do in the human body.
When brain cells were injected into the surrounding gel, the cells released chemicals that prompted the engineered vessels to sprout new branches, extending the network. A similar system could supply blood to engineered tissue before transplant into the body.
The system also shows promise as a model for tumour progression.
When the researchers added to their system a signalling protein for vessel growth that's overabundant in cancer and other diseases, new blood vessels sprouted from the originals. These new vessels were leaky, just as they are in human cancers.
The system could also be used to study malaria, which becomes fatal when diseased blood cells stick to the vessel walls and block small openings, cutting off blood supply to the brain, placenta or other vital organs.
"I think this is a tremendous system for studying how blood clots form on vessels walls, how the vessel responds to shear stress and other mechanical and chemical factors, and for studying the many diseases that affect small blood vessels," said co-author Dr. José López, a professor of biochemistry and haematology at UW Medicine and chief scientific officer at the Puget Sound Blood Center.
Future work will use the system to further explore blood vessel interactions that involve inflammation and clotting.