Researchers track down stem cells in blood vessel walls

Researchers from the University of Helsinki believe they have found stem cells that play a crucial role in the new growth of blood vessels. These cells that reside in the walls of vessels will open up new horizons in the treatment of cardiovascular disorders and cancer once we learn to isolate and efficiently produce them.

Researchers track down stem cells in blood vessel walls

Docent Petri Salvén has spent two decades researching the mechanisms of angiogenesis – the growth of new blood vessels – to identify ways to accelerate or block it. He is particularly intrigued by the source of highly specialised endothelial cells in blood-vessel walls and by the possibility to enhance or prevent the generation of such cells.

In an adult body, new blood-vessel growth is needed to repair damaged tissue or organs – resulting from, for example, a heart attack or stroke – but cancerous tumours can also build new vessels to ensure their own growth. There is demand for both kinds of mechanisms: those that accelerate angiogenesis and those that block it. Some drugs based on the inhibition of angiogenesis are already in use.

It was long believed that new cells in the blood-vessel walls of adults derived from the bone marrow, but Salvén and his team refuted this hypothesis in their research, published by the PNAS journal in 2008.

Cell transfer could halt cancer or grow a new blood vessel

A recent study of Salvén’s, published in PLoS Biology, suggests that in adult blood vessels, stem cells reside in the wall as individual cells among normal endothelial cells. “We isolated endothelial cells that were extremely capable of dividing from the blood-vessel walls of mice and then discovered the same cells in human blood vessels as well as in the growing blood vessels of human cancerous tumours,” Salvén reports.

Researchers cultivated the stem cell candidates in culture and found that a single cell was able to produce tens of millions of new blood-vessel-wall cells.

Mouse experiments also confirmed the important role played by new cells. A mouse with fewer such cells than normal experienced weaker growth of new blood vessels, and the growth of cancerous tumours also decelerated. Similarly, transferred stem cells quickly resulted in a large number of new functioning blood vessels in the place in which the cells were planted.

Research on these new stem cells is slow due to the difficulty of distinguishing them among all the other cells in blood-vessel walls. Salvén’s team identified a few molecular structures on the surface of stem cells, which can be used to track the cells.

“We are now looking for more cell-surface structures that help identification and enable us to efficiently isolate more cells,” says Salvén. “A tenfold increase in the efficiency and accuracy of cell isolation would result in volumes that would be useful in the cell transfer treatment of humans.”

Plos Biology: On the Hunt for Vascular Endothelial Stem Cells »»

Research Database TUHAT: Petri Salvén »»

Salvén Lab »»

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Text: Päivi Lehtinen
Photo: Petri Salvén Lab
Translation: Language Services, University of Helsinki
University of Helsinki, digital communications

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