Stem cells stimulate the body to repair itself

The study, published in the journal Cell Stem Cell, is the work of researchers in the UK. The team, led by Sarah Rankin, used healthy mice and, using drugs, tricked their bone marrow into releasing two types of adult stem cells: endothelial progenitor cells that make new blood vessels, and mesenchymal stem cells, that can turn bone into cartilage and can also suppress the immune system.

This is the first study in which these two types of stem cell have been mobilised. Stem cells that can make new blood vessels - haemopoeitic stem cells - have already been used in bone marrow transplants.

The researchers used different drugs to mobilize the two types of stem cells. They hope their findings will help to develop new therapies to repair and regenerate damaged tissue: for example in heart patients and sports injuries. Another application could be to stimulate bone marrow to generate more immune suppressing stem cells as a way to treat autoimmune disease such as rheumatoid arthritis where the body's own immune system attacks itself. Healthy mice were treated with two growth factors that occur naturally in bone marrow, VEGF and G-CSF, and then gave them a new drug called Mozobil.

Compared with mice that had no treatment, the bone marrow of the mice that were given VEGF followed by Mozobil released about 100 times more endothelial and mesenchymal stem cells into the bloodstream. The bone marrow of mice treated with G-CSF and Mozobil released more haematopoietic stem cells; this is the treatment that is already used in bone marrow transplants.

Researchers explain that, although there are already repair mechanisms in the body that work all the time, in severe damage, these mechanisms may not be sufficient. Releasing the extra stem cells may accelerate the healing process.

Further research will concentrate on examining whether stem cells can be used to repair cardiac tissue in mice that have had heart attacks.