Blood vessel stem cells found
Scientists have discovered stem cells in blood vessel walls that are able to form whole new vessels when transplanted into mice. They have also identified a trigger on the surface of the cells that could be used to turn off blood vessel growth.
The growth of new blood vessels is crucial to the repair of tissue and organs after injury or disease, such as heart attack, but also to the rapid growth of tumours, which require large amounts of oxygen. So understanding how vessels form would help doctors both repair healthy tissue and fight cancer.
Like in other parts of the body, scientists know that stem cells are responsible for growth and repair of blood vessels, but until now they did not know where the stem cells were found. The latest research now shows that there is a small population of cells, called vascular endothelial stem cells (VESCs), within the walls of blood vessels.
The team that discovered them isolated single VESCs, tagged them with a fluorescent probe, grew them up in the lab and then transplanted them into mice. 14 days later when the mice were dissected, they found whole blood vessels tagged with the fluorescent probe, showing that they had formed from the original isolated cells. The team then turned to look at what was controlling the growth rate of the VESCs. They identified a protein on the cell surface called c-kit which was not present on the surface of other blood vessel cells. They found that when they removed this protein vessel formation was severely reduced. Realising that this could be used to stop blood vessel growth in tumours, the researchers took mice that are predisposed to develop cancer and genetically modified them to lack c-kit. The mice lacking c-kit had much smaller tumours than unmodified mice. This suggests that a therapy that blocks c-kit activity could reduce or prevent tumour growth in people.