Siberian biologists create artificial blood vessels
Using a combination of nano-materials and human cells, Siberian scientists have designed artificial blood vessels. Their similarity to human blood vessels will minimize the possibility of rejection by the body's immune system, as well as help avoid inflammation and blood clots.
Many experts in tissue engineering from around the world, especially the U.S., Great Britain and Germany, are working to develop artificial blood vessels. Some are created from the cells of lambs, while others are made with a 3D printer.
Scientists from Novosibirsk University and the Institute of Cytology and Genetics proposed another method - not just using artificial blood vessels, but filling them with living cells.
The result is based on membranes comprised of biodegradable polyester - polycaprolactone and chitosan - made by treating the chitin shells of shrimp with an alkaline substance. Scientists colonized them with human heart cells - endothelial cells which line the blood vessels - and smooth muscle cells to create vascular tone.
Strong blood vessels
"The combination of selected cells makes the graft strong and durable," said Novosibirsk State University researcher Anna Smirnova. "The mixture of chitosan and polycaprolactone also has its advantages. Chitosan has fantastic biological characteristics: it doesn't provoke an immune response, it's biocompatible when grafted into the body and has antimicrobial properties. But the materials derived from it are not strong enough."
That's why scientists mixed chitosan with polycaprolactone, which compensates for this shortcoming. This mixture is much more potent than each one individually.
After a series of experiments, researchers calculated the optimal ratio of components for the most effective tissue generation on the membrane surface. They realized that human cells after colonization retain their functional characteristics.
Experiments on mice followed, and new vessels were implanted into the aortas. Tests confirmed that the cell-filled grafts have sufficient strength to react to variations in blood pressure.
"Ultrasound examination and magnetic resonance tomography confirmed that after implantation, and for the entire duration of the experiment, the aorta of the mice remains passable and a pulsatile blood flow is retained in the implant," said Smirnova.
Histological analysis shows that after any given period of time - be it two weeks, or 24 weeks - the engineered grafts continue to form the necessary functional layers of cells and integrate well into the surrounding tissue. The Siberian scientists will continue their research.